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monitoring systems and are not processed as EEG. How-
two authors is to obtain a baseline BIS value prior to
ever, in some situations, the programmed pacing rate and
induction of anesthesia to determine whether abnormal
current pro¬le causes the extraneous paced signal to be
CNS status may impact the reliability of the consciousness
interpreted as an EEG signal. The presence of this artifact
monitor.27
in¬‚uences the BIS value.
BIS and Pharmacologic Responses
Nitrous oxide (N2O)
A variety of medical/surgical
MEDICAL/SURGICAL DEVICES.

devices generate high-frequency electrical or mechanical The BIS Index is sensitive to the clinical pattern of adminis-
signals and may produce artifacts within the measured tration and the relative dosing of N2O and other anesthetic
EEG. Such devices include ¬‚uid- and forced-air“warming agents. For example, as a sole agent administered for seda-
devices,24 intravenous administration devices, mechan- tion, N2O appears to have little sedative effect at concen-
ical surgical instruments, and cardiopulmonary bypass trations of up to 50%, and the BIS value similarly is unaf-
fected.28 In one volunteer study, however, administration
machine.
36 Scott D. Kelley


of 70% N2O did produce unconsciousness but without a cosmetic surgery, is more fully described in Chapters 1
change in BIS value. A recent paper demonstrated a lack of and 4.
correlation with OAAS scores during bupivicaine epidural
anesthesia with 33%, 50%, and 67% N2O sedation.29 Etomidate
The intraoperative addition of N2O to inhalation anes- Etomidate, another intravenous anesthetic agent, also has
thesia has had variable effect on measured BIS values. One a unique pharmacodynamic pro¬le. Anesthesia induction
study reported a dose-dependent decrease in BIS when with etomidate frequently results in skeletal muscle exci-
20“60% N2O was administered, whereas another found no tation (i.e., myoclonus, tremor, fasciculations). This clin-
change in BIS with addition of 50% N2O.30 In studies with ical effect may result in the presence of high EMG activity
intravenous balanced techniques (propofol/remifentanil and thus increased BIS during the period of musculoskele-
or midazolam/fentanyl), the addition of 70% N2O did tal excitement. However, following induction (or with the
not alter BIS with or without surgical stimulation. In onset of neuromuscular blocking agent activity), BIS will
a study focusing on the response to laryngoscopy, N2O re¬‚ect the hypnotic state of most patients. The ability of
administration prevented the movement response but not the BIS Index to re¬‚ect the sedative effect of etomidate dur-
a hemodynamic response, without changing BIS.31 Thus, ing induction and allow effective titration of an etomidate
infusion has been reported.36
the effect of N2O administration prevented the movement
response but does not per se seem to be nonlinear with
respect to hypnosis, and the contribution to the anesthetic
CLINICAL MANAGEMENT
state may be via its potent analgesic effects.
In clinical situations where artifact seems likely to have
Ketamine in¬‚uenced the consciousness-monitor value, the anesthe-
Ketamine, an intravenous anesthetic of unique chemical sia provider should review all of the available data col-
and pharmacodynamic characteristics, plays an important lected by the monitoring system. For example, additional
role in of¬ce-based practices as well as cosmetic anesthe- data provided by the EMG trend display can be used to
sia. One of the observed physiologic effects of ketamine evaluate increasing level-of-consciousness values. Where
is the dose-dependent activation of the EEG (increase in there is concern regarding the accuracy of the currently
high-frequency activity). Thus, frequently following bolus displayed consciousness value, a simple strategy facilitates
administration of a clinically effective dose of ketamine a rapid determination of the potential for artifact, includ-
(e.g., 0.4“0.5 mg · kg’1 ), both BIS and Entropy values ing assessment of the signal quality index (SQI), the EMG
tend to increase transiently, and bolus administration of activity, and the real-time EEG signal. The BIS system con-
ketamine presumably modi¬es the relationship between tinuously calculates a signal-quality index to re¬‚ect the
these parameters and the level of consciousness.32 amount of quality EEG data entering the BIS system over
The timing of administration of ketamine is also impor- the previous minute and provides that data on the dis-
tant. When smaller dissociative doses of ketamine are play monitor. In situations of extraneous artifact correctly
administered in the setting of propofol-induced sedation, detected by the BIS processing system, the SQI will decline
it has no acute effect on BIS but minimizes the increase rapidly.
in BIS in response to profound stimulation.33 Following Many, but not all, extraneous artifacts have been
bolus administration of ketamine, BIS values decreased to reported to be associated with increased “EMG” activity
baseline values during low-dose propofol-infusion admin- as measured by the BIS system. Because the EMG param-
istration. (1 mg · kg’1 · hr’1 ).33 eter displayed in BIS systems utilizes a high-frequency
Several reports have described the successful use and spectral window (70“110 Hz), many electromechanical
clinical utility of BIS during intravenous techniques devices may generate an artifact that is apparent within
involving ketamine administration (i.e., dose administra- the EMG parameter. In addition to assessment of the SQI
tion <1 mg · kg’1 ) with simultaneous propofol admin- and EMG parameters, inspection of the current, real-time
istration.34,35 The clinical application of this technique, EEG directly recorded (and displayed on the monitor)
including the use of BIS monitoring in the setting of may assist in the assessment of the patient and current
Level-of-Consciousness Monitoring 37


anesthetic effect. The EEG tracing may reveal a clearly thesia providers can make more informed decisions about
contaminated appearance, thus facilitating the determi- the dosing and balance of anesthetic agents and other adju-
nation that artifact may be affecting the calculation of the vant therapies such as analgesics, local anesthesia in¬ltra-
BIS. However, some subtle artifacts may not be apparent tion, and cardioactive agents.
in the assessment of the EEG recording from the monitor Improved anesthetic agent administration is the great-
screen. est bene¬t that results from level-of-consciousness mon-
In situations where the consciousness-monitor value itoring. Using these new parameters, the clinician can
seems discordant with another clinical parameter, EEG manage patients within the optimal plane of anesthesia
assessment can facilitate clinical assessment of the ade- effect and reduce the unwanted occurrence of excessive
quacy of anesthetic effect. Typical EEG waveform patterns or inadequate anesthetic effect. Clinical investigations of
will be seen frequently and, with experience, are easily rec- consciousness monitoring during general anesthesia con-
ognized (see Fig. 3-2). It is important to note that no single sistently demonstrate approximately a 20% reduction in
pattern of EEG waveform will always be observed at each intraoperative anesthetic use and a consistent reduction
in the time for emergence from general anesthesia.37 With
BIS value.
The varieties of special situations discussed are impor- consciousness-monitoring technology, the question”
tant reminders to anesthesia clinicians about the need “Am I overdosing my patient?””is often quite easy to
to always consider level-of-consciousness monitoring an answer.
additional parameter used in their assessment and man- Emerging data suggests that subtle differences in anes-
agement of patients under their care. No single monitoring thetic effect may be associated with patient outcomes days,
weeks, and even months after surgery.38 This type of long-
parameter (whether the consciousness-monitor value or
another vital sign) should be used alone or in isolation to term perspective, assessing the impact of anesthesia man-
determine patient care. agement, may broaden the scope of positive patient out-
comes associated with consciousness monitoring beyond
the immediate perioperative period.
SUMMARY: CLINICAL BENEFITS OF
Level-of-consciousness monitors allow the anesthesia
CONSCIOUSNESS MONITORING
clinician to trend and manage changes in the hypnotic state
during a case. Throughout the period of anesthesia care”
The use of level-of-consciousness monitoring supports
during induction, maintenance, and emergence”it high-
three primary components of anesthesia care: vigilance,
lights the important transitions in level of consciousness
intraoperative patient assessment, and anesthetic agent
and provides valuable patient-management data. Level-of-
management.
consciousness monitoring is an important tool to enable
Vigilance is a cornerstone of anesthesia care. Level-of-
the best intraoperative care and postoperative outcomes
consciousness“monitoring technologies provide continu-
important in the patient undergoing cosmetic surgery.
ous documentation of central nervous system status dur-
ing anesthesia care. As such, these monitors provide early
indicators of changes in brain effect due to anesthetic dos- REFERENCES
ing and delivery. Level-of-consciousness monitoring can
1. Flaishon R, Windsor A, Sigl J, et al.: Recovery of conscious-
help answer the question: “Is my patient adequately anes-
ness after thiopental or propofol. Anesthesiol 86:613,1997.
thetized?” In the operating room, dramatic changes in 2. Gibbs FA, Gibbs EL, Lennox WG: Effect on the electroen-
cephalogram of certain drugs which in¬‚uence nervous activ-
blood pressure and heart rate may occur and require the
ity. Arch Intern Med 60:154,1937.
anesthesia professional to make rapid diagnostic assess-
3. Rampil IJ: A primer for EEG signal processing in anesthesia.
ments and timely interventions. Level-of-consciousness Anesthesiol 89:980,1998.
monitoring provides data that can facilitate decision- 4. Sigl JC, Chamoun NC: An introduction to bispectral
index analysis for the electroencephalogram. J Clin Monit
making and management approaches in many of these
10:392,1994.
situations. Consciousness monitors are not a substitute
5. Johansen JW, Sebel PS: Development and clinical appli-
for keen clinical judgment. However, using consciousness cation of electroencephalographic bispectrum monitoring.
monitoring information as part of their assessment, anes- Anesthesiol 93:1336,2000.
38 Scott D. Kelley


ically determined low-voltage electroencephalographic sig-
6. Bruhn J, Bouillon TW, Shafer SL: Bispectral index (BIS) and
nal. Anesthesiol 89:1607,1998.
burst suppression: Revealing a part of the BIS algorithm.
23. Kaisti KK, Jaaskelainen SK, Rinne JO, et al.: Epileptiform dis-
J Clin Monit Comput 16:593,2000.
charges during 2 MAC sevo¬‚urane anesthesia in two healthy
7. Myles PS, Leslie K, McNeil J, et al.: Bispectral index moni-
volunteers. Anesthesiol 91:1952,1999.
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24. Hemmerling T, Fortier JD: Falsely increased bispectral index
randomised controlled trial. Lancet 363:1757,2004.
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8. Glass PS, Bloom M, Kearse L, et al.: Bispectral analysis mea-
using forced-air-warming therapy of the head. Anesth Analg
sures sedation and memory effects of propofol, midazolam,
95:322,2002.
iso¬‚urane, and alfentanil in healthy volunteers. Anesthesiol
25. England MD, Mosca S, Wong G, et al.: BIS XP platform per-
86:836,1997.
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9. Lubke G, Kerssens C, Phaf H, et al.: Dependence of explicit
Analg 94:SCA79,2002.
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26. Pemberton PL, Dinsmore J: Bispectral index monitoring
Anesthesiol 90:1,1999.
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10. Struys M, Jensen EW, Smith W, et al.: Performance of the
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ARX-derived auditory evoked potential index as an indica-
27. Renna M, Handy J, Shah A, et al.: Does dementia affect the
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bispectral index? Anesthesiol 95:A286,2001.
and hemodynamic measures during propofol administra-
28. Park KS, Hur EJ, Han KW, et al.: Bipectral index does not
tion. Anesthesiol 96:803,2002.
correlate with observer assessment of alertness and seda-
11. Katoh T, Bito H, Sato S: In¬‚uence of age on hypnotic
tion scores during 0.5% bupivicaine epidural anesthesia with
requirement, bispectral index, and 95% spectral edge fre-
nitrous oxide sedation. Anesth Analg 103:385,2006.
quency associated with sedation induced by sevo¬‚urane.
29. Rampil IJ, Kim JS, Lenhardt R, et al.: Bispectral EEG index
Anesthesiol 92:55,2000.
during nitrous oxide administration. Anesthesiol 89:671,
12. Nakayama M, Hayashi M, Ichinose H, et al.: Values of the bis-
1998.
pectral index do not parallel the hemodynamic response to
30. Coste C, Guignard, B, Menigaux C, et al.: Nitrous oxide
the Rapid Increase in iso¬‚urane concentration. Can J Anesth
48:958, 2001. prevents movement during orotracheal intubation without
13. Bloom M, Greenwald S, Day R: Analgesics decrease arousal affecting BIS value. Anesth Analg 91:130,2000.
response to stimulation as measured by changes in bispectral 31. Hans P, Dewandre PY, Brichant JF, et al.: Comparative effects
index (BIS). Anesthesiol 85:A481,1999. of ketamine on bispectral index and spectral entropy of the
14. Schneider G, Wagner K, Reeker W, et al.: Bispectral index electroencephalogram under sevo¬‚urane anaesthesia. Br J
(BIS) may not predict awareness reaction to intubation in Anaesth 94:336,2005.
surgical patients. J Neurosurg Anesthesiol 14:7,2002. 32. Vereecke HE, Struys MM, Mortier EP: A comparison of
15. Gan TJ, Glass PS, Windsor A, et al.: Bispectral index bispectral index and ARX-derived auditory evoked poten-
monitoring allows faster emergence and improved recov- tial index in measuring the clinical interaction between
ery from propofol, alfentanil, and nitrous oxide anesthesia. ketamine and propofol anaesthesia. Anaesthesia 58:957,
Anesthesiol 87:808,1997. 2003.
16. Song D, Joshi G, White PF: Titration of volatile anesthetics 33. Friedberg BL: The effect of a dissociative dose of ketamine on
using bispectral index facilitates recovery after ambulatory the bispectral index (BIS) during propofol hypnosis. J Clin
anesthesia. Anesthesiol 87:842,1997. Anesth 11:4,1999.
17. Friedberg BL: Propofol ketamine anesthesia for cosmetic 34. Friedberg BL, Sigl JC: Clonidine premedication decreases
surgery in the of¬ce suite, chapter in Osborne I (ed.), Anes- propofol consumption during bispectral index (BIS) moni-
thesia for Outside the Operating Room. International Anesthe- tored propofol-ketamine technique for of¬ce-based surgery.
siology Clinics. Baltimore, Lippincott, Williams & Wilkins, Dermatol Surg 26:848,2000.
41:39,2003. 35. Friedberg BL, Sigl JC: Bispectral index (BIS) monitoring
18. England MR: The changes in bispectral index during a hypo- decreases propofol usage in propofol-ketamine of¬ce-based
volemic cardiac arrest. Anesthesiol 91:1947,1999. anesthesia. Anesth Analg 88:S54,1999.
19. Billard V: Brain injury under general anesthesia: Is monitor- 36. Doenicke AW, Roizen MF, Hoernecke R, et al.: TIVA with
ing of the EEG helpful? Can J Anesth 48:1055,2001. etomidate or propofol in day-case surgery: Is the bispectral
20. Bruhn J, Bouillon TW, Shafer SL: Electromyographic activ- index a useful parameter to lower the maintenance dose?
ity falsely elevates the bispectral index. Anesthesiol 92:1485, Anesth Analg 88:S470,1999.
2000. 37. Liu SS: Effects of bispectral index monitoring on ambulatory
21. Schultz B, Schultz A, Plein S, et al.: Slowing down of the anesthesia: A meta analysis of randomized controlled trials
EEG during hypoventilation in emergence from anesthesia. and a cost analysis. Anesthesiol 101:311,2004.
Anaesthetist 40:672,1991. 38. Monk TG, Saini V, Weldon BC, et al.: Anesthetic man-
22. Schnider TW, Luginbuhl M, Petersen-Felix S, et al.: Unrea- agement and one-year mortality after noncardiac surgery.
sonably low bispectral index values in a volunteer with genet- Anesth Analg 100:4,2005.
4 The Dissociative Effect and Preemptive Analgesia
Barry L. Friedberg, M.D.



INTRODUCTION
THE DISSOCIATIVE EFFECT
PREEMPTIVE ANALGESIA
CONCLUSION




agent. Ketamine was supposed to be the magic “silver
INTRODUCTION
bullet,” for which no other drugs were required. Negative
A Medline search for the number of articles that con- psychotomimetic experiences (in the form of hallucina-
tain “ketamine” yielded 8,553, with 6,905 in English. A tions or dysphorias) were visited not only on unsuspect-
Melvyl (University of California system catalog) search for ing patients but also on unsuspecting PACU personnel.
the number of books containing “ketamine” as a word Unhappy PACU staff had to try to manage these wild and
in the title or keyword yielded thirty two, with twenty unpleasant emergence issues. Quickly, ketamine gained a
in English (many are dissertations). A “Google” search reputation as an unpredictable agent. At least two gen-
for “ketamine” yielded over 250,000 sites. As reported on erations of anesthesiologists have given ketamine a wide
the World Wide Web, a 50 mg dose of ketamine (route berth.
of administration unclear) taken by itself produces an However, anesthesiologists involved in pediatric burn
“NDE” or “near death experience,” whereas a 100 mg units ¬nd IM ketamine, mixed with atropine, very useful
dose of ketamine produces an “out of body” experience. for painless dressing changes in children under the age of
In the world of the street drug user, ketamine is a recre- nine or ten.
ational drug with the reputation of unpredictable, nasty Older children require the concomitant use of ben-
side effects. Uncontrolled “street” experimentation pro- zodiazepines to mitigate the tendency for negative psy-
duced a “solution” for the nasty side effects commonly chotomimetic side effects of the drug. Shortly after
referred to as “kitty ¬‚ipping.” “Kitty ¬‚ipping” is the inges- ketamine™s introduction, the veterinary anesthesia com-
tion of methylenedioxymethamphetamine (MDMA), or munity adapted it. Animals did not complain of hallu-
“Ecstasy,” to produce a positive state of mind before “¬‚ip- cinations. It was also virtually impossible to destroy an
ping” to “kitty,” a code name for the “k” word ketamine. animal for lack of the correct body weight in the dosage
MDMA is not to be confused with NMDA, N-methyl calculation.
D-aspartate, the receptors blocked by ketamine. Even in the 21st century, anesthesia trainees con-
For all that has been written about the drug ketamine, tinue to express concerns about the psychotomimetic side
the reader could assume that much is understood. Despite effects of the drug. Ketamine is a protean drug, changing
the prodigious output of articles, books, and web sites, faces within different contexts! Ketamine™s most bene¬cial
ketamine remains maligned, feared, and misunderstood usage is not as a solo anesthetic agent but as an adjuvant.
as an anesthetic agent. In Vinnik™s hands, it has been used as a separate bolus after
a hypnotic level of diazepam had been titrated.1 Vinnik,
Ketamine was originally introduced to the anesthe-
sia profession as a complete, total intravenous anesthetic a plastic surgeon, described the dissociative phenomenon



39
40 Barry L. Friedberg


as “all or nothing” without reference to NMDA receptors. negative experience was the last time Friedberg attempted
The patient either is immobile for the injection of the local to use his PK MAC technique for that surgeon. Fried-
analgesia or is not. Movement with injection implies that berg was forced to reevaluate Vinnik™s claim that there
more ketamine would be required. After a test dose of 5 mg was no upper limit on the amount of ketamine one
diazepam, 15 mg diazepam followed to induce a state of could use, especially when using a short-acting hypnotic
hypnosis. Vinnik administered diazepam through an exter- propofol.
nal jugular IV to minimize the phlebitis seen when using A forty-two-year-old, Caucasian female patient with a
peripheral veins. positive history of previous PONV and motion sickness
More diazepam in 5“10 mg increments, up to 40 mg was anesthetized for a rhinoplasty with the MIA„ tech-
total, is given until the desired hypnotic level was achieved. nique on March 1, 2005. The initial 50 mg of ketamine
Vinnik™s initial dose of ketamine was 75 mg, based on adult failed to produce a complete dissociative effect within
brain weights being essentially equal. Ketamine™s dissocia- two to three minutes. A second 50 mg dose of ketamine
tive effect is independent of adult body weight. Adminis- was administered and an additional two minutes elapsed
tering the 75 mg ketamine dose, Friedberg observed sev- before the surgeon attempted to inject the local anesthetic.
eral patients in his ¬rst ¬fty cases emerging with horizontal The patient continued to display movement in response to
nystagmus. This undesirable side effect led Friedberg to try the needle. A third 50 mg dose of ketamine was adminis-
a 50 mg dose of ketamine. Horizontal nystagmus may also tered and an additional minute was allowed to elapse. After
induce PONV in patients with a positive history of motion a total of 150 mg ketamine, the patient was completely
sickness. immobile for the injection of her breasts. The BIS dur-
Vinnik further asserted that there was no upper limit ing the entire sequence of securing the dissociative effect
on the amount of ketamine one could use. More ketamine remained below 75. Unfortunately, the surgery was com-
simply meant a longer emergence. This caveat turns out pleted an hour after the last dose of ketamine had been
to be true only if one is using a long half-life drug like administered. The patient emerged promptly but experi-
diazepam. More ketamine does prolong emergence. How- enced persistent horizontal nystagmus. She experienced
ever, with propofol, the upper useful, aggregate dose of hours of PONV at the of¬ce, delaying her discharge to
ketamine is 200 mg.2 In Vinnik™s practice, patients were home. The patient experienced PONV for approximately
discharged to the care of a nurse for twenty-four hours. six hours total postoperatively. At that time, the PONV
Aldrete scores in Vinnik™s patients that Friedberg observed spontaneously resolved.
would have precluded discharge by most anesthesiologists. Consider the case duration when pursuing a complete dis-
When asked if he was concerned about the state of postop- sociative effect.
erative grogginess of his patients, Vinnik responded that In retrospect, this patient probably would have been
he wanted them sleepy for two to three days to prevent better served with a less-than-complete dissociative effect.
them from undoing his surgery (Vinnik CA, Personal com- The patient did not experience hallucinations, hyperten-
munication, March 1992). Vinnik felt if the patients were sion, or tachycardia from the ketamine. She had no com-
too awake after surgery, they would be less inclined to fol- plaint of postoperative pain. The persistent horizontal nys-
low their postoperative instructions. tagmus that produced the PONV could probably have
In case #51 (8/24/92), before Friedberg understood been avoided by accepting a less-than-total dissociative
the difference between diazepam and propofol protection effect for a relatively brief case. Had the case been a four-
from ketamine-induced hallucinations, a total of 650 mg hour abdominoplasty or a four- to six-hour rhytidectomy,
ketamine was administered over ¬ve hours. During the there would likely have been suf¬cient time for the patient
case, the surgeon refused to give additional local analgesia to redistribute and metabolize the ketamine. Fortunately,
after the initial injection (see Chapter 1, Table 9). Fried- this patient suffered no negative effect on her surgical out-
berg was forced to administer progressively more ketamine come. On the ¬rst-postoperative-day interview, her sis-
to compensate for inadequate local analgesia. The patient ter admitted that they were both so motion sensitive that
emerged three hours postoperatively. She had severe per- they had to sit in the front of the bus and use scopo-
sistent nystagmus and ultimately experienced emesis. This lamine (Transderm r ) patches wherever they traveled. The
The Dissociative Effect and Preemptive Analgesia 41


termed functional disorganization5 of nonspeci¬c path-
Table 4-1. Essential dissociative concepts
ways in the midbrain and thalamic areas.6,7 How does the
preceding description translate into clinical terms for the
1. Neither the size of the brain nor the number of
NMDA receptors varies appreciably in adults. anesthesiologist seeking to utilize ketamine?
2. The number of NMDA receptors does NOT vary Visualize the dissociative effect of ketamine as a “mid-
with body weight or skeletal muscle mass in
brain spinal.” The ketamine “midbrain spinal” sets the
adults.
stage for preemptive analgesia (vide infra). The cortex can-
3. Ketamine™s dissociative effect is independent of
adult body weight. not respond to (noxious) signals it does not receive! No
4. Visualize the dissociative effect of ketamine as a “wind-up” phenomenon is likely without afferent stimu-
“midbrain spinal” (i.e., no afferent signals
lation.
reach the cortex).
After obtaining identical dissociative effects with a
5. Hypnosis ¬rst, then dissociation.
50 mg dose of ketamine in 90-pound women and muscu-
lar 250-pound men, Friedberg concluded that the number
of NMDA receptors does NOT vary with body weight or
skeletal muscle mass in adults. Investigators attempting
patient accepted the author™s explanation of her postoper-
to reliably reproduce preemptive analgesia with ketamine
ative experience and his apology.
doses based on body weight that fall short of saturating the
This patient is only the third patient in the author™s
number of NMDA receptors (i.e., the dissociative effect)
¬fteen-year experience that required more than 100 mg
are doomed to, at best, variably positive8’13 and, at worst,
of ketamine to achieve a complete dissociative effect.
negative results.14’19
Curiously, both of the other two cases were also rhino-
A recent negative outcome paper by Vallejo et al.19 was
plasties. The author™s series includes more than 3,000 PK
received for publication in January 2002. Although Fried-
MAC cases (including 1,500 MIA„ technique). Learning
berg™s 1993 paper was cited as a reference in Vallejo et al.,19
is an ongoing process. Our activities are rightly described
none of his more recent papers were.2,20 Vallejo et al.19
as the “practice” of medicine, not the “perfection.” Patients
were unable to demonstrate a difference in PONV rates.
can continue to teach us, if we listen. Patients will accept
Their negative outcome was not surprising. Both groups
less-than-perfect outcomes if some humility is exhibited
received emetogenic iso¬‚urane 0.5“1.5%. Vital signs and
(see Table 4-1).
visual analog scale scores were utilized as indices of anes-
Building on Vinnik™s work with ketamine, Friedberg
thetic depth, not a level-of-consciousness monitor, like the
substituted propofol for diazepam. Friedberg described
BIS. Vallejo et al.19 administered ketamine 1“1.5 mg · kg’1
the use of a ketamine bolus after a stable level of hypnosis
or doses between 70“120 mg without subsequent local
from propofol had been achieved with a gradual propo-
analgesia. Friedberg advocates doses of 50 mg ketamine
fol induction.3 Friedberg™s PK technique is a MAC or the
(independent of body weight) followed by local anesthe-
MIA„ technique when patients are premedicated with po
sia. Vallejo et al.19 had no speci¬c endpoint of hypno-
clonidine, the propofol is titrated with a quantitative infu-
sis before giving a greater-than-50-mg dose. To no sur-
sion pump, and the BIS monitors the effect of the propofol
prise, they reported an elevated heart rate and increased
(see Appendix in Chapter 1).
incidence of dreaming in the ketamine group. Friedberg™s
endpoint of propofol for ketamine administration is pre-
cise and reproducible, that is, BIS 70“75. The outcome of
THE DISSOCIATIVE EFFECT
Friedberg™s approach is the lack of historically described
ketamine side effects. Table 4-2 contrasts the number of
The primary site of CNS action of ketamine appears to
medications administered by Vallejo et al.19 with Fried-
be the thalamoneocortical projection system.4 Ketamine
berg™s MIA„ technique. By failing to follow the “hypno-
selectively depresses neuronal function in parts of the
sis ¬rst, then dissociation” rule, followed by adequate local
cortex (especially association areas) and thalamus while
anesthesia, Vallejo et al.19 violated the entire algorithm for
simultaneously stimulating parts of the limbic system,
the successes published by Friedberg.2,3,20
including the hippocampus. This process creates what is
42 Barry L. Friedberg


patients were immobile for the injection. Using dissocia-
Table 4-2. Drugs in Vallejo et al.19 compared with
tion for the injection of the local anesthetic would have
MIA„ technique2
obviated the need for opioids, sevo¬‚urane, endotracheal
intubation, and neuromuscular blockade.
Friedberg MIA R
Vallejo et al.19 technique2 A 0.6% PONV rate has been reported in Friedberg™s
high-risk practice,2 compared with Pavlin et al.14 reporting
1. Midazolam (1“2 mg) IV 1. Clonidine (0.2 mg) PO
2. Glycopyrrolate (0.2 mg) 2. Glycoprryolate (0.2 mg) a 33% PONV rate. “High risk” has been de¬ned as non-
3. Propofol (2 mg · kg’1 ) 3. Propofol (150 ug · kg’1 smoking, female patients with a previous PONV/motion-
monitored by vital q 20 seconds “
sickness history having elective cosmetic surgical proce-
signs & visual analog minibolus) monitored
dures greater than two hours in duration. Patients perceive
scores by BIS titrated to <75
4. Ketamine (0.5 mg · 4. Ketamine 50 mg IV PONV on emergence as caused by the anesthetic. In
kg’1 ) push contrast, they do not blame the anesthesiologist for
5. d-Tubocuarare 5. Lidocaine with
PONV after taking postoperative pain medication! Opi-
6. SCH epinephrine (injected
oid avoidance de¬nes a nonopioid, preemptive analge-
7. Ketorolac to adequate analgesia)
8. Iso¬‚urane sia (NOPA) that is essential to the elimination of PONV
9. Oxygen
with the MIA„ technique. Opioid avoidance facilitates
10. Nitrous oxide
room air, spontaneous ventilation (RASV) in the major-
11. Rocuronium
12. Neostigmine ity of healthy patients. Elimination of routine adminis-
tration of oxygen, a drug that supports combustion or
¬re, is an obvious safety advantage for laser resurfacing
cases.20
Pavlin et al.14 used a multimodal approach to diminish
postoperative pain. Like Friedberg, they used rofecoxib as
a preemptive anti-in¬‚ammatory drug. Rofecoxib was with-
PREEMPTIVE ANALGESIA
drawn from the market by the F. D. A. in 2004. The dose of
ketamine Pavlin et al.14 administered was 0.2 mg · kg’1 . Adequate local analgesia is mandatory to facilitate the
Ketamine was given prior to the skin incision but after NOPA of the MIA„ technique. Without a level-of-con-
the afferent stimulus of the local analgesic! This feature of scious monitor, like BIS, it is impossible to differentiate
their study design demonstrates their probable belief that between patient movement from inadequate local analge-
a sevo¬‚urane/fentanyl anesthetic would block incoming sia and patient movement from inadequate propofol.
stimuli to the cortex from the local injection. GA does not Patients receiving Friedberg™s MIA„ technique (i.e., BIS
reliably block the entry of all noxious stimuli to the cortex. 60“75) experienced the lesser trespass than general anes-
Injection of local anesthesia under GA alone will not reli- thesia (i.e., BIS 45“60 with systemic analgesia). Propofol
ably produce preemptive analgesia. was titrated to BIS 60“75 prior to the dissociative effect
At 0.2 mg · kg’1 , the average dose of ketamine in the from the 50 mg ketamine dose. Over 1,500 MIA„ tech-
Pavlin et al.™s14 82.5 kg patients was 16.5 mg. This dose of nique patients have experienced no recall of their surgical
ketamine is highly unlikely to saturate the NMDA recep- experience without concomitant benzodiazepine admin-
tors in the adult brain. At best, only 80% of patients will istration (see Table 4-3).
achieve a dissociative effect at 25 mg; 98% of patients obtain Without the ability to differentiate brain-based (imply-
a dissociative effect with a 50 mg dose of ketamine. Because ing inadequate propofol) versus spinal-cord“based move-
Pavlin et al.14 were titrating their anesthetic to BIS 44 (com- ment, the anesthesiologist may be hard-pressed to con-
pared with Friedberg™s reports of 70“75), they could have vince the surgeon to inject more local analgesia. Too often,
safely given a 50 mg dissociative dose of ketamine without patient movement engenders comments from the surgeon
producing hallucinations, tachycardia, or hypertension. that the patient is “too light.” The anesthesiologist™s invari-
Assuming they had given the ketamine prior to the injec- able response is “needs more local.” Without the ability
tion of the local, paralyzing their patients would have made to measure either component, there can be no resolution
it impossible for Pavlin et al.14 to determine whether their of this familiar argument. The “too light” versus “needs
The Dissociative Effect and Preemptive Analgesia 43


ate that EVERY cosmetic procedure, including abdomino-
Table 4-3. Essential preemptive analgesia
plasty, can be performed successfully solely under local
concepts
anesthesia! This is true only if the patient is so motivated
1. Reproducible preemptive analgesia occurs and the surgeon is very skilled with local anesthesia. Local
administering the dissociative concepts. analgesia with an awake, alert patient is not the preferred
2. GA does not reliably block the entry of all
technique for most surgeons and patients. Despite his ser-
noxious stimuli to the cortex.
vice being requested, the anesthesiologist should maintain
3. Injection of local anesthesia under GA alone will
not reliably produce preemptive analgesia. some perspective and humility when approaching the cos-
4. Adequate local analgesia is mandatory to metic surgical patient.
facilitate the nonopioid, preemptive analgesia
Commonly, anesthesia services provided in residency-
(NOPA) of the MIA„ technique.
training situations tend to be GA with neuromuscular
5. Without a level-of-consciousness monitor, like
BIS, it is impossible to differentiate between blockade or major neuraxial anesthesia. The young sur-
patient movement from inadequate local
gical trainee may be deprived of the feedback to know
analgesia and patient movement from
how well his local analgesia is, or is not, working in these
inadequate propofol.
6. Insisting on adequate local analgesia during the circumstances. Further, the surgical trainee, as well as
case minimizes most of postoperative pain- his anesthesia counterpart, may also be denied the abil-
management issues.
ity to see how few postoperative pain-management issues
7. When BIS is 60“75 with a “zero” EMG and
remain when adequate intraoperative local analgesia is
patient movement, the surgeon must be
educated to inject more local! employed under dissociative anesthesia. (See Chapters 9
8. Pain signals can be transmitted to the patient™s and 10 for speci¬cs in providing adequate local analgesia
cortex, even in the presence of a
for cosmetic surgery.) More importantly, if every proce-
vasoconstricted ¬eld.
dure can be performed solely under local, the anesthesiol-
ogist must be able to justify every medication administered
to the cosmetic surgical patient.
Patient movement occurring at BIS 60“75 with EMG
more local” argument becomes circular and unresolvable.
at “zero” (more accurately, 30 on the EMG scale [right
Everyone becomes frustrated and the patient suffers
side] but reads zero on the BIS scale [left side]) is most
needlessly. Demonstrating a BIS 60“75 (with an iso-
likely being generated from the spinal cord level. When
electric EMG) to the surgeon who may complain about
trending the EMG as a secondary trace, it is visually easier to
patient movement should provide ample information to
recognize a vertical spike compared to the horizontal factory
defuse the “too light” complaint. The surgeon is correct
default setting. To trend EMG as a secondary trace, go to
that the patient is “too light” but incorrect about the
the advanced screen setup page. Once there, set the “save
etiology. The correct solution 99% of the time is more
setting” button after selecting EMG as a secondary trace.
local analgesia!
Patient movement with BIS 60“75 and a “zero” EMG
The surgical ¬eld can be blanched from the epinephrine
de¬nes an adequate level of propofol hypnosis for the
effect, yet the patient may still experience pain.
MIA„ technique. When patient movement occurs while
This can be very confusing to the surgeon, who observes
the BIS is 60“75 and the EMG remains “zero,” more local
the epinephrine effect and believes there must be concomi-
analgesia is the most effective means to preserve the out-
tant lidocaine effect. Only after three total injections (the
come advantages of the MIA„ technique. Spinal-cord“
initial and two subsequent ones) of local to an area, con-
generated movement is devoid of the implication of aware-
tinued patient movement is managed with an additional
ness and recall. While spinal-cord“generated movement
25“50 mg ketamine.
may be annoying to the surgeon, it generally does not dis-
Assuring on adequate local analgesia during the case min-
rupt the surgical ¬eld. Passive restraints of the patient™s arms
imizes most postoperative pain-management issues.
and legs are recommended with the MIA„ technique. When
BIS can serve as a “case management” tool. It is criti-
restraining the arm, pronate it so the wrist is facing the arm
cally important for the anesthesiologist trying to provide
board.
a value-based service to the cosmetic surgeon to appreci-
44 Barry L. Friedberg


Spinal-cord“generated movement is merely annoying.
Table 4-4. Dissociation and preemptive analgesia
The same degree of movement could be extremely dele-
terious for a patient having cerebral aneurysm clipping. 1. Variable preemptive analgesic effect with less
Attempts to suppress patient movement with more propo- than a dissociative effect.
2. Time to dissociative effect typically 2“3 min.
fol may be successful but are not productive. Propofol does
s/p ketamine injection.
not block transmission of noxious stimuli to the cortex. 3. Prevent hallucinations from ketamine by having
Propofol suppression of patient movement will only add a stable level of propofol in the brain (BIS 70“75)
BEFORE giving the ketamine.
to the problems of postoperative pain management. More
4. Create stable level of propofol with incremental,
propofol is only a Band-Aid r when the patient needs a
not bolus, induction.
“suture.” Attempts to suppress patient movement with 5. No ketamine in the last twenty minutes of a case.
200 mg,a in divided doses, is the upper limit of
more ketamine will often result in exceeding an aggre- 6.
ketamine when using a short-acting agent like
gate dose of 200 mg. Whether ketamine is mixed with
propofol.
the propofol or administered separately, once the 200 mg
aggregate dose is exceeded, patients do not emerge quickly a Especially in motion sickness sensitive patients, con-
sider accepting a less-than-perfect dissociative effect by
or without side effects like horizontal nystagmus. N. B. This
restricting ketamine dose to 50 mg for cases less than
caveat does not apply to cases less than sixty to ninety minutes
ninety minutes.
without superior outcomes. The anesthesiologist will not
be successful in convincing the surgeon or his nurses that
the MIA„ technique is a technique to be preferred over
opioid-based IV sedation, regional anesthesia, or GA. in Anesthesiology was ampli¬ed by an insouciant, accom-
The skin is the largest organ in the body. The skin panying editorial. “It is not clear to me that the failure of
has the largest number of nerve endings. Failure to block preemptive analgesia is a great loss in the pragmatic clinical
setting.”24 Other studies in the peer-reviewed anesthesia
negative afferent signals from the skin is a common fea-
ture of the negative studies showing failure to obtain pre- literature beyond the academic purview of Anesthesiology
emptive effect with ketamine. GA primarily depresses the have con¬rmed what many clinicians have known for some
time.25’28
CNS™s ability to respond to afferent traf¬c. Opioid-based
mu receptor blockade also fails to prevent the entry of Table 4-4 summarizes the salient points of dissociation
noxious, painful stimuli from reaching the cortex. Opioid- and preemptive analgesia with the MIA„ technique. Table
medicated, awake patients still acknowledge that they have 4-5 is included to help avoid known, possible errors per-
pain. They state it just doesn™t “bother them.” Opioids forming the MIA„ technique. The worst possible error
modify only the affective response but not the perception is to administer ketamine before the propofol.
of pain. General anesthesia does not reliably block all afferent A stable, hypnotic level of propofol must precede the
stimuli from reaching the brain. The brain responds to these ketamine if hallucinations are to be avoided. While teach-
noxious stimuli by secreting several different polypeptides ing a resident, Friedberg noted that the resident had
that are responsible for the “wind-up” phenomenon.21 administered the ketamine when the BIS was 87. Fried-
After patients emerge from GA, it is apparent that neg- berg moved to rapidly administer propofol to lower the
ative signals have reached the cortex. Postoperative pain BIS level. Subhypnotic doses of propofol (i.e., BIS >75) fail
management continues to be an issue for many patients.22 to block ketamine hallucinations. Predictably, the patient
Observing patients emerge essentially pain free is one of emerged hallucinating. The hallucinations were promptly
the hallmarks of the MIA„ technique. eliminated with 2 mg IV midazolam prior to PACU trans-
Failure to dissociate prior to stimulation (injection port. A calmed patient was then delivered to the PACU.
and/or incision) is why a scholarly review of eighty ran- The PACU nurses were spared the emotional trauma of
domized clinical trials, including eight with systemic dealing with a hallucinating patient.
NMDA receptor antagonists, by Moiniche et al.23 con- The anesthesiologist wishing to perform the MIA„ tech-
cluded a negative potential bene¬t of preemptive analgesia nique, especially in an institutionally based environment,
on postoperative pain. The power of this negative review must avoid traumatizing his supporting PACU staff.
The Dissociative Effect and Preemptive Analgesia 45


The BIS monitor is indifferent to the surgeon™s (and the
Table 4-5. Errors to Avoid with the MIA„
anesthesiologist™s) ego. Without the BIS, it may be very
Technique
dif¬cult to persuade the surgeon to inject more local after
1. Ketamine before the propofol: NO the initial injection. It is not uncommon for the surgeon
2. Ketamine before LLR/LVR or BIS >75 (i.e., PK to comment (on the request for more local) that the ¬eld
MAC without BIS): NO
is already blanched. The surgeon™s (not entirely unrea-
3. Ketamine at BIS >75: NO
sonable) assumption is that, if the ¬eld is blanched from
4. Bolus propofol induction: NO
5. Inadequate local analgesia: NO, use the power the epinephrine, the patient must also be numb from the
of BIS/EMG
lidocaine.
6. Opioids instead of more local analgesia: NO
Pain signals can be transmitted to the patient™s cortex even
7. Ketamine instead of more local analgesia: NO
in the presence of a vasoconstricted ¬eld.
8. Give >200 mg total ketamine or in last 20 min:
NO There is no more ef¬cacious IV agent to remedy inad-
9. Tracheostomize patient instead of IV lidocaine:
equate local analgesia than more local analgesia injected
NO
into the surgical ¬eld. Only after two subsequent lido-
10. SCH instead of IV lidocaine: NO
11. Persist trying to obtain complete dissociative caine injections after the initial one (three total injections)
effect by administering more than a single 50-mg should one administer an additional 25“50 mg ketamine
dose of ketamine for brief cases (i.e., 60“90
to suppress patient movement.
min.), especially in motion sensitive patients: NO
One of Friedberg™s surgeons was not very gifted admin-
istering local analgesia. To compensate, this surgeon would
inject 1,000 mg lidocaine with epinephrine in each breast
(as 50 cc of 2%). The total lidocaine dose was 2,000 mg
Do not permit hallucinations to occur or promptly treat
with epinephrine! Most anesthesiologists would be very
them if they do. Hallucinating patients will only con¬rm
uncomfortable, at the least, with a surgeon injecting this
the well-earned, anti-ketamine bias among the nursing
amount of lidocaine. Working with the MIA„ technique,
staff. Do NOT administer ketamine until the BIS is <75 in
this surgeon performed over 100 breast augmentation
the context of a gradual propofol induction.
surgeries without any stigmata of lidocaine toxicity. As
If one is performing PK MAC without a BIS monitor, do
long as SpO2 >95% and not more than 2,000 mg total
not administer ketamine until both the loss of lid re¬‚ex [LLR]
lidocaine (typically as 400 cc 0.5%, 200 cc 1%, or 100 cc
and loss of verbal response [LVR].
Another error is to hasten the induction with a 1 mg · 2%) is used in the surgical ¬eld(s), none of the stigmata of
’1 lidocaine toxicity has been observed in Friedberg™s expe-
kg bolus of propofol. The brain level of propofol will
rience, either intra- or postoperatively.
peak and then rapidly decline about the same time the
Insisting on adequate intraoperative local analgesia
ketamine level is peaking. Ketamine concentration peak-
for the patient is a critical step in creating preemptive
ing in the brain while propofol concentration is declining
analgesia and dramatically reducing postoperative pain-
from a hypnotic level is functionally the same error as
management issues!
giving the ketamine before the propofol. Both error types
set the stage for (avoidable) emergence hallucinations or
dysphorias.
CONCLUSION
As the patient™s advocate in the OR, the anesthesiologist
must insist on adequate local analgesia, either by provid- Preemptive analgesia does exist but only under speci¬c and
ing it himself or helping the surgeon understand the need clearly de¬ned, reproducible conditions. The dissociative
for adequate local. During patient movement, the anes- effect is regularly observed when the NMDA receptors are
thesiologist should demonstrate the BIS level of 60“75 to saturated. The dissociative effect sets the stage for reliable
the surgeon, who will likely complain about the patient preemptive analgesia. There are a ¬nite number of NMDA
being “too light.” receptors in the spinal cord and mid-brain. This number
When BIS is 60“75 with a “zero” EMG and patient move- does not appear to vary with body weight in adults. A
ment, the surgeon must be educated to inject more local. 50 mg IV ketamine bolus will effectively saturate the ¬xed
46 Barry L. Friedberg


number of NMDA receptors in the adult brain of approx- 13. Pavlin DJ, Horvath K, Pavlin EG, et al.: Preincisional treat-
ment to prevent pain after ambulatory hernia surgery. Anesth
imately 98% of patients.
Analg 97:1627,2003.
Very few exceptions will occur (vide supra). Completely 14. Adam F, Libier M, Oszustowicz T, et al.: Preopera-
blocking incoming noxious signals to the cortex using the tive small-dose ketamine has no preemptive effect in
patients undergoing total mastectomy. Anesth Analg 89:444,
dissociative effect (the so-called mid-brain spinal) is most
1999.
likely responsible for the observed preemptive analgesia.
15. Dahl V, Ernoe PE, Steen T, et al.: Does ketamine have pre-
“Hypnosis (propofol to BIS <75) ¬rst, then dissociation” emptive effects in women undergoing abdominal hysterec-
(50 mg ketamine) eliminates the historically reported tomy procedures? Anesth Analg 90:1419“22,2000.
undesirable side effects of ketamine.29 16. Mathisen LC, Aasbo V, Raeder J: Lack of preemptive anal-
gesic effect of (R)-ketamine in laparoscopic cholecystectomy.
Acta Anaesthesiol Scand 43:220,1999.
REFERENCES
17. Yaksch W, Lang S, Reichhalter R, et al.: Perioperative small-
dose S(+)-ketamine has no incremental bene¬cial effects on
1. Vinnik CA: An intravenous dissociation technique for out-
post-operative pain when standard-practice opioid infusions
patient plastic surgery: Tranquility in the of¬ce facility. Plast
are used. Anesth Analg 94:981,2002.
Reconstr Surg 67:799,1981.
18. Van Elstraete AC, Lebrun T, Sanfedo I, et al.: Ketamine does
2. Friedberg BL: Propofol ketamine anesthesia for cosmetic
not decrease post-operative pain after remifentanil-based
surgery in the of¬ce suite, chapter in Osborne I (ed.), Anes-
anesthesia for tonsillectomy in adults. Acta Anesthesiol Scand
thesia for Outside the Operating Room. International Anesthe-
48:756,2004.
siology Clinics. Baltimore, Lippincott, Williams & Wilkins,
19. Vallejo MC, Romeo RC, Davis DJ, et al.: Propofol-ketamine
41:39,2003.
versus propofol-fentanyl for outpatient laparoscopy: Com-
3. Friedberg BL: Propofol-ketamine technique. Aesth Plast Surg
parison of postoperative nausea, emesis, analgesia and recov-
17:297,1993.
ery. J Clin Anes 14:426,2002.
4. Miyasaka M, Domino E: Neural mechanisms of ketamine-
20. Friedberg BL: Facial laser resurfacing with propofol-
induced anesthesia. Int J Neuropharmacol 7:557,1968.
ketamine technique: Room air, spontaneous ventilation
5. Corssen G, Domino EF: Dissociative anesthesia: Further
(RASV) anesthesia. Dermatol Surg 25:569,1999.
pharmacologic studies and ¬rst clinical experience with the
21. Thompson SWN, King AE, Woolf CJ: Activity-dependent
phencylcidine derivative CI-581. Anesth Analg 45:29,1968.
changes in rat ventral horn neurons in vitro, summation of
6. Massopust LC Jr, Wolin JR, Albin MS: Electrophysiologic
prolonged afferent evoked depolarizations produce a D-2-
and behavioral responses to ketamine hydrochloride in the
amino-5-phosphonovaleric acid sensitive windup. Eur J
Rhesus monkey. Anesth Analg 51:329,1972.
Neurosci 2:638,1990.
7. Sparks DL, Corssen G, Aizenman B, et al.: Further studies
22. Cousins MJ, Power J, Smith G: Pain “ A persistent problem
on the neural mechanisms of ketamine induced anesthesia
(Labat lecture). Reg Anesth Pain Med 25:6,2002.
in the Rhesus monkey. Anesth Analg 54:1889,1975.
23. Moinche S, Kehlet H, Berg J: A qualitative and quantitative
8. Kwok RFK, Lim J, Chan MTV, et al.: Preoperative ketamine
systemic review of preemptive analgesia for postoperative
improves postoperative analgesia after gynecologic laparo-
pain relief. Anesthesiol 96:725,2002.
scopic surgery. Anesth Analg 98:1044,2004.
9. Menigauz C, Fletcher D, Dupont X, et al.: The bene¬ts 24. Hogan Q: No preemptive analgesia. Is that so bad? Anesthesiol
of intraoperative small dose ketamine on postoperative 96:526,2002.
pain after anterior cruciate ligament repair. Anesth Analg 25. Woolf CJ, Chong MS: Preemptive analgesia: Treating post-
90:1129,2000. operative pain by preventing the establishment of central
10. Royblat L, Korotkurutchko A, Katz J: Post-operative pain: sensitization. Anesth Analg 77:362,1993.
the effect of low dose ketamine on general anesthesia. Anesth 26. Ong KS, Lirk P, Seymour RA: The ef¬cacy of preemptive
Analg 77:1161,1993. analgesia for acute postoperative pain management: A meta-
11. Fu ES, Miguel R, Scharf JE: Preemptive ketamine decreases analysis. Anesth Analg 100:757,2005.
post-operative narcotic requirements in patients undergoing 27. McQuay HJ: Pre-emptive analgesia: A systematic review of
abdominal surgery. Anesth Analg 84:1086,1997. clinical studies. Ann Med 27:249,1995.
12. Suzuki M, Tseuda K, Lansing PS, et al.: Small-dose 28. McQuay HJ: Pre-emptive analgesia. Br J Anaesth 69:1,1992.
ketamine enhances morphine-induced analgesia after out- 29. Friedberg BL: Hypnosis ¬rst, then dissociation. Anesth Analg
patient surgery. Anesth Analg 89:98,1999. 96:911,2003.
5 Special Needs of Cosmetic Dental Patients
James A. Snyder, D.D.S.



INTRODUCTION
FINDING AN ANESTHESIA PROVIDER
DENTISTRY IN THE HEALTHCARE UNIVERSE
UNIQUE REQUIREMENTS OF DENTAL PROCEDURES
AIRWAY MANAGEMENT
Endotracheal Anesthesia
Nonintubated Anesthesia
MONITORING
ANESTHESIA TECHNIQUE
ANESTHESIA AND PAIN CONTROL OPTIONS
POSTOPERATIVE NAUSEA AND VOMITING (PONV)
VENUE SELECTION
CONSUMER DUE DILIGENCE




bypass surgery (CABG) is usually more than 5 millimeters
INTRODUCTION
in diameter whereas the distance from the outside of a
Cosmetic dental procedures are increasing.1 Americans front tooth to the pulp (nerve) is less than half that.
have demonstrated their interest in cosmetic medical pro- Modern dentistry is truly powerful. Many cosmetic and
cedures through their interest in television features, doc- restorative treatment options are available from dentists
umentaries, and “reality” programming. This program- in all parts of the country. Ceramic or polymer laminates
ming often features dental procedures ranging from recon- (veneers) and crowns can be attached to teeth or titanium
structive maxillofacial surgery through complex dental implants placed in the bone allowing a ¬xed, permanent
restorative procedures to simple cosmetic teeth bleaching. correction for lost, damaged, or irregularly placed teeth. If
Modern dental practice offers many treatment solutions one does not have enough bone for placement of implants,
to almost any patient need or desire. Some of these proce- arrays of bone-grafting procedures are available to replace
dures require highly technical and precise care to produce the lost bone so that dental implants can be placed. Skele-
a desirable outcome. The dentist must obtain near-perfect tal deformities can be corrected with maxillofacial surgery.
conditions in an otherwise hostile environment. Most of these processes can be tedious, and dental treat-
The primary operating area, a person™s mouth, is a small, ment is often anxiety-provoking for many people.
dark, wet hole with plenty of very delicate, moving parts
(see Fig. 5-1). An ill-timed twitch or swallow, a hiccup or
FINDING AN ANESTHESIA PROVIDER
sigh, a startled wince and a big problem has been created.
Further, in all cases, the treatment objects”tooth, peri- There is no American Dental Association (ADA) accred-
odontal tissue, dentoalveolar ridge”are tiny. For exam- ited specialty for anesthesiology! Whereas medicine,
ple, a coronary artery being grafted during coronary artery nursing, and even veterinary medicine have approved


47
48 James A. Snyder


dated oral and written test similar to the one administered
by the American Board of Anesthesiology.3 Success leads
to Diplomate status”Board Certi¬cation. These persons
are Dentist Anesthesiologists (DAs). This is currently the
most reliable credential for dentist anesthesia providers.
Board certi¬cation as an Oral and Maxillofacial Surgeon
(OMS) requires only a four-month rotation in anesthesia-
related areas. One hundred deep-sedation cases or general
anesthetics must be documented.4
Some dental graduate programs contain a sedation
module or rotation. These vary widely in intensity and
duration. Some of the ADA-recognized specialties and
many general practice residencies have sedation require-
Figure 5-1. The crowded environment of dental work. Note the ments varying from exposure to competence. A common
securing of the endotracheal tube and head wrap.
concern lies in whether a dentist (or nonanesthesiologist
physician) trained for a light level of sedation can res-
cue a patient who inadvertently goes into the next deeper
level. These programs vary from a single-day didactic
training and certi¬cation programs in anesthesiology,
(lecture) to several-days didactic with clinical exposures.
the ADA does not. The ADA is currently the only
The programs are continuing education (CE), not part of
Department of Education“approved accrediting body for
a graduate or undergraduate curriculum. The ADA pro-
dentists. Although it does not accredit a specialty in anes-
vides detailed guidelines for each level of instruction but
thesiology, the ADA does have extensive guidelines for the
has no oversight mechanism.2 Further, examination of
educational requirements expected of providers for all lev-
participants is spotty or nonexistent. In-depth exposure
els of pain and anxiety control in dentistry. The ADA stip-
to anesthesia and anesthetized patients is very minimal in
ulates two years of anesthesia training in Part 2 of the
undergraduate dental education and only slightly greater
Guidelines for the Teaching the Comprehensive Control of
in most postgraduate dental curricula.5
Anxiety and Pain in Dentistry. Part 2 is entitled “Teach-
State regulations play an enormous role in the anesthe-
ing the Comprehensive Control of Anxiety and Pain at the
Advanced Education Level.”2 sia strategy for dental patients. Because of the very high risk
of patient harm and several high-pro¬le media events fol-
Although the ADA provides guidelines for dental anes-
lowing dental-of¬ce misadventures, states have sought to
thesia training, the ADA has refused to recognize those
regulate anesthesia safety for dental patients. The absence
who have successfully completed that training as special-
of a professional standard-bearer (i.e., a specialty group
ists in anesthesia. Also, the ADA has not requested that
such as the American Society of Anesthesiologists [ASA]
the Commission (CODA) accredit programs that state
provides for medicine) and a hodgepodge of legacy anes-
they meet or surpass those standards. Despite these cir-
thesia techniques have made some state laws and regula-
cumstances, there are trained dentists (and physicians and
tions highly speci¬c. Providing modern, advanced forms
nurses) who can provide reliable anesthesia care. Further,
of anesthesia care for dental patients will have to begin with
there are credentials offered that identify dentists with a
an analysis of one™s respective state™s laws, regulations, and
proper anesthesia background.
customs.
The American Society of Anesthesiologists (ASA)
Although an increasing number of anesthesiologists
requires two or more years (at least twenty-four months)
and nurse anesthetists have offered their services to
of training solely in anesthesiology for membership.
dental patients in recent years, the total number of quali-
The American Dental Board of Anesthesiology (ADBA)
¬ed providers to this group of patients is very small. Dentist
reviews curricula in the dentist anesthesia residency pro-
anesthesiologists have proliferated in states where regula-
grams. Further, the ADBA examines those completing two
tions thoughtfully provide for this higher standard of care
years of anesthesia training with a rigorous day-long, vali-
Special Needs of Cosmetic Dental Patients 49


but are absent from large blocks of the country. Anesthe- gies relying on methohexital, could be still taught through
siologists and nurse anesthetists may be excluded from the 1990s. It may also be easier to understand how these
conventional practice for dental patients by poorly crafted practice modes could ¬nd their way into a state™s legal
regulations.6 code.
One thing remains constant, regardless of the venue or
treatment: general anesthesia or deep sedation (which can
UNIQUE REQUIREMENTS OF
quickly change to general anesthesia) should be provided
DENTAL PROCEDURES
by a specialist in anesthesia, that is, an anesthesiologist or
dentist anesthesiologist or nurse anesthetist.7 All dental treatment is in the airway. Aspiration risk is high.
Most dental procedures must be accompanied by copi-
ous irrigation to cool the rotary instruments (drills) used.
DENTISTRY IN THE HEALTHCARE UNIVERSE
The result of all that drilling often causes chips, pieces,
What are “Legacy” anesthesia techniques and why do they and fragments of hard tissue to ¬‚y around. Dentists use a
affect anesthesia practice for dental patients? The Institute lot of very small instruments that can get slippery when
of Medicine (IOM) published its study of dental educa- wet. Persons with oral guarding, including hyperactive gag
tion in 1995 with a 345-page bound volume. Some of its re¬‚ex, prevent the simplest treatments without a profound
conclusions are instructive in seeking perspective on the level of anesthesia. A small mandibular range of motion
differences between dental and medical practices. or large tongue size may necessitate general anesthetic to
On the surface, it would seem there should be little dif- gain adequate access to the treatment area. Treatment in
ference in the need and application of anesthesia services. close proximity to the airway requires opening the mouth
After all, it™s only a centimeter from a cosmetic labial pro- and may require manipulating the head. Either (or both)
cedure to a dental one. This is sometimes a pretty long maneuver(s) may produce a loss of airway patency. These
centimeter. Why would there be such widely different reg- circumstances are not usually issues for other cosmetic
ulations and techniques? One important explanation can procedures, and each has a priority in anesthesia planning.
be found in some of the IOM conclusions. Sensory perception of the oral and pharyngeal areas is
“The mission of education is undermined by curric- extremely high. Protective re¬‚exes produce very reactive
ula and faculty that have become out of touch with the responses to intrusions in the oropharynx. For this reason,
needs of students and prospective practitioners, patients, it is usually necessary to have a deeper, more complex anes-
or communities. . . . Further, each mission is weakened by thesia plan than for treatments of seemingly similar acuity
dental schools™ isolation from the intellectual and organi- on other parts of the body. For instance, a person may
zational life of the university, from the broader research permit traction of a skin pedicle after light sedation and
community, and from the larger health care system. . . . local anesthesia in¬ltrated into the area but react sharply
Dentistry has been relatively slow to support outcomes after similar traction of the tongue. Complex muscle and
research, to investigate the rationale for practice varia- nerve interrelations abound and the autonomic overlay
tions, and to demand proof of cost-effectiveness for new is very present in the head and neck. Many individuals
technologies.” 5 “Dental accreditation has been criticized have to compete for a con¬ned space around the patient™s
for being in¬‚exible, overly prescriptive, insuf¬ciently inde- head. Current practice puts at least the dentist, a chair-
pendent of dental society leadership, and too focused on side assistant, the anesthesiologist, and everybody™s gear,
process and structure. It is said, thus, to sti¬‚e innovation. equipment, and instruments in a pretty small space. Some
Further, the current system is criticized as being too little pretreatment choreography is a prerequisite!
concerned with outcomes.”5 Since the 1995 IOM report, Looking at treatment acuity or plan alone can™t always
“There is simply no evidence that I know of showing that determine anesthetic strategy. For instance, a person with
dental education is following the prescient recommenda- hyperactive gag re¬‚ex (or Parkinson™s tremors) may intend
tions of the IOM,” former Dean Nash opined in AGD fully to cooperate, require minimal invasive treatment, but
Impact, May 2000.8 Given this background, it may be easier require considerable anesthesia management to prevent a
to visualize why operator-anesthetist strategies, or strate- tremor or wretch at an inconvenient time (e.g., while the
50 James A. Snyder


dental drill is spinning at 400,000 RPM near the tongue). cosmetic dental procedures do not employ an endotra-
Patients manifesting presenile dementia often seem docile cheal tube (vide infra). Endotracheal intubation is typi-
but react violently when an oral trespass is attempted. cally performed with general anesthesia (BIS 45“60 with
Deeper anesthesia than expected is often needed to obtund systemic analgesia), not MAC or “deep sedation.” An anes-
this reaction for even the simplest oral examination or thesia machine and all the mandated monitoring are also
treatment. employed.
Dental phobia, “White coat syndrome,” fear of nee- Hospitals and stand-alone surgicenters are always
dles, fear of pain or the unknown are pretty common in equipped with anesthesia machines and ASA-speci¬ed
monitoring.7 Increasingly, busy of¬ces have installed them
healthcare. Dentistry has its own level of phobia. Dental
Phobia is in the DSM,9 a kind of pantheon of fear. Fear for their anesthesia provider. Further, mobile anesthesia
of dental treatment is so universal that it is a common providers have found transportable anesthesia machines
usage metaphor. It is a common plot device for authors and monitors allowing safe, fully compliant anesthetics to
and movies (e.g., the 1976 movie “Marathon Man,” with be provided almost anywhere. As most who have worked
Dustin Hoffman and Sir Laurence Olivier). The fear is in military ¬eld hospitals or third world medical facili-
really, really deep for many people. From where does it ties know, what™s critical isn™t the place but the profes-
come? While the impact of any treatment in the mouth is sionals with the necessary equipment. Modern technique
probably more likely to have negative responses, the answer including BIS monitoring, simple end-tidal CO2 measure-
is most likely that it actually is unpleasant. A majority of the ment, ultra-short acting agents, and computerized infu-
population goes for dental care and discovers that some- sion pumps make intubated general anesthesia a practical
times it sounds bad, tastes worse, and sometimes hurts. option.
When it hurts, it hurts in a sharp, ugly, startling way that An obstacle to endotracheal intubation for dental pro-
leaves an indelible memory, often crossing generations. cedures has been the requirement for a nasal approach.
Regrettably, only a very small percentage of dentists uti- Although armored tubes placed orally can be manipulated
lize even the most rudimentary pain- and anxiety-control inside the mouth to allow access for most dental proce-
techniques (other than local anesthetic injection). For this dures, the constant manipulation increases both intraop-
reason, patients and their dentists have few options to erative and postoperative risk. Additionally, tube manip-
reduce the likelihood of a bad experience or prevent the ulation increases mouth, throat, and larynx soreness,
repeat of one that has already happened. leading to lower satisfaction levels for patients. Some den-
Studies show large numbers of the American population tal cosmetic procedures may be compromised by the pres-
do not seek regular dental care.10’11 These studies usually ence of an oral tube. For instance, precise occlusal registra-
show that if advanced forms of anesthesia where available, tion may not be possible and exact lip position cannot be
they would seek treatment.13’15 The offer of competent determined. Actually, occlusal registration is the relation-
anesthesia care would likely increase interest in cosmetic ship of the teeth in various jaw positions such as protruding
dental procedures. or moved laterally. The exact position of tooth cusps and
ridges determines function and comfort. N. B. “Occlusal
registration” is the indexing of the relationship of the teeth.
AIRWAY MANAGEMENT
It is sometimes called the “bite.” An accurate occlusal regis-
Endotracheal Anesthesia tration can have profound in¬‚uence on the ¬nal cosmetic
outcome.
Anesthesia management for dental procedures requires
DAs and others who have extensive experience provid-
the usual consideration of operator or surgeon work-
ing anesthesia for dental procedures use nearly exclusively
ing conditions and patient safety and comfort with the
a nasal approach. Like most things, experience improves
additional concerns highlighted herein, and in addition
outcomes. A common strategy is to dilate the nasal passage
usually requires managing the airway in a dental of¬ce.
with lidocaine gel or Surgilube„“lubricated straight nasal
The concerns outlined would suggest to most anesthe-
airways over about ¬ve minutes. Three to six increasing
siologists that an endotracheal tube is required”period.
sizes are used in the side with the least resistance. Selecting
Interestingly, most sedation and anesthesia provided for
Special Needs of Cosmetic Dental Patients 51


the nasal passage is aided by obtaining a panoramic den- and neck procedures. Although there is a massive array of
tal x-ray. The ¬nal airway should be one size larger than rigid and ¬‚exible anesthesia standard connectors allowing
the planned ET tube. Heating the ET tube in hot water or almost any conceivable positioning, RAE„ can usually
in the folds of a hot towel is very important in minimiz- be used without additional connectors to allow improved
ing trauma. Studies of examined optimum time of heating access to the treatment area. A recent modi¬cation in the
and the minimum temperature have been done.17 About tip design of the ETT, the Parker,„ reduces trauma during
45—¦ “50—¦ C is fairly reliable. insertion.18 Tubes shielded from laser are available and
ET tube will resist boiling for a short time. However, the are necessary if laser is used in the mouth with an oral
patient will be burned if the tube is heated to temperatures intubation.
in excess of 60—¦ C. This combination of nasal passage selec- Muscle-relaxant use is not necessary for intubation.
tion, dilation, lubrication, and heated tube nearly elim- While 50% of DAs routinely intubate, none use muscle
relaxants to achieve it.18 How is this done? Current litera-
inates the other nasal intubation issue”epistaxis (nose-
bleeds). Because the entire treatment is around the head ture contains numerous successful techniques using high
and the head is going to be moved during treatment, the doses of opioids or ketamine. However, the use of topi-
properly positioned tube must be secured (see Fig. 5-1). cal local anesthesia for the airway has been the favorite
technique for DAs.19 Delivery of lidocaine spray by LTA,„
Nasal tubes need to be secure for length (to prevent one-
lung ventilation), but they also need to be free from twist- atomizer, or transcrichoid injection renders the cords non-
ing, torquing, rotating, or otherwise spindling or stapling. reactive to the tube passing. A topicalized airway low-
Tube movement during the procedure can result in nose- ers the overall drug requirement for the general anesthe-
bleeds after extubation as well. sia. Cheaper, faster, better anesthesia and recovery are the
Patient eye protection is required for dental procedures desired outcome goals. LTA„ delivery is the most popu-
for all anesthetic levels. Goggles or safety glasses are ¬ne for lar route of administration. Delivery of topical lidocaine
awake or conscious sedation strategies, but tape, drapes, to the airway requires about ¬ve minutes to achieve effect.
and/or a speci¬c protective device are needed for deeper For those persons with reactive airway, good results have
levels. There is just too much going on around the head not been achieved with 2% lidocaine, 100 mg, .
to protect the patient™s eyes. An operator™s ¬nger, a ¬‚ying Even if a muscle relaxant is necessary to the anesthesia
tooth fragment, a dropped instrument (remember, these plan, recent drug introductions have reduced the concerns.
things are tiny and slippery), or a drip of some dental mate- Several rapid-onset, short-acting nondepolarizing muscle
rial could all easily end up in an unprotected eye. The risk relaxants are available. Depending on the procedure dura-
of microbe inoculation of the eye in the dental treatment tion, it may not be necessary to use a reversal agent if the
environment is very high. Ultra high-speed dental hand- muscle relaxant was used only to facilitate intubation. The
pieces (drills) with copious irrigation to protect the tooth presence of nondepolarizers in the anesthesia technique
and bone from its heat create a large aerosol cloud ¬lled requires the availability of a reversal agent and a periph-
with everything that could be found in the mouth”virus, eral nerve stimulator. Further, an unexpected incomplete
bacteria, fungus”a real microbiology workshop. Eye pro- reversal could mean a transfer to a nearby intensive care
tection has to be considered in securing the nasal tube. unit.
After all, there is only so much room and this is also going A common concern of operating dentists is access to the
to be the operating area. Luckily, dental treatment teams posterior teeth when patients have decreased mandibular
usually work at roughly the three and nine o™clock posi- range of motion (ROM). Normal adult opening at the
tions around the head, leaving the twelve o™clock position incisors is usually about 45“55 mm. However, a massetter
for the anesthesiologist. muscle spasm or intracapsular temporomandibular joint
Who would have thought the simple endotracheal tube dysfunctions such as an anteriorly trapped meniscus can
(ETT) could be improved on? Disposable, safer materials, dramatically reduce this opening. Muscle relaxants can
pneumatic cuffs, and size and pressure options for the cuffs also improve the ROM. A fully secure airway not only
all evolved. The RAE„ nasal and then oral curved tubes allows a safe and precise anesthetic but also gives the oper-
are a nice convenience, especially for dental and other head ator the fullest possible treatment technique latitude: exact
52 James A. Snyder


patient positioning for optimum access, protection from
treatment detritus, limitless irrigation, and no treatment
interference. A helpful additional bene¬t of the intubated
dental patient is that auxiliary staff need little additional
skills to assist for these procedures. Loss of airway due to
positioning or contamination is very dif¬cult when com-
pared to other airway techniques.
A common criticism of intubation for dental proce-
dures is that it takes too long. A careful induction of the
type described herein takes about ¬fteen to twenty min-
utes from entering the operating room to ready for treat-
ment. Although this is probably twice the time needed
for a deep sedation, the time is quickly recovered with
Figure 5-2. Dr. Synder with electronic stethoscope, with both
interest during the treatment time in which interruptions
monitors and patient within his eye scan. BIS is 44.
for throat packing, coughing, gagging, or hypoventilation
don™t occur. Additionally, time is saved due to complete
freedom in head position and mouth opening. mouth. Occasionally, a perfectly positioned nasopharyn-
geal airway becomes useless with the mouth open. A big
Nonintubated Anesthesia tongue can displace or compress the ori¬ce of the airway. A
Since most dental anesthesia does not involve endotracheal useful strategy in these cases is to try using a low-pressure
intubation, how is it done? Although a laryngeal mask air- endotracheal tube. Position it as if it was a nasopharyngeal
way (LMA)„ ”or one of the variations”may be used airway, in¬‚ate the cuff, and cut off the excess. It is possible
in a carefully prepared patient while staying short of gen- even to use two nasal airways, connect them with a com-
eral anesthesia (Fig. 5-4), the rostral tongue posturing and mercially available adaptor to an anesthesia circuit, and
large oral tube makes most dental treatment more dif¬- proceed semiclosed. Sometimes there is no exact nasal air-
cult. In limited situations, the LMA„ can be useful. When way position possible. In those cases, a “go”/”no go” deci-
treatment considerations allow for it, the LMA„ can be sion is necessary. Cancel, lighten to conscious sedation, or
used as a “super” throat pack allowing high-volume irri- deepen to general anesthesia.
gation or higher protection from bleeding with very small Everything about (dental) anesthesia starts with airway.
aspiration risk. With the LMA„ properly placed, a small- Because the “prime directive” (protect the airway) and the
bore suction can be placed through the nose to the top of treatment area are in competition, extra and even extraor-
the LMA„ , then a gauze throat pack placed. This strategy dinary planning is needed for dental cases (see Fig 5-2).
also greatly reduces swallowed blood, thereby decreasing Millions of MAC and general anesthetics are provided for
the PONV risk. dental patients every year. Most are done without a fully
Oral pharyngeal airways (and variants like COPA„ ) are protected airway! The public and the profession believe
completely in the way during dental treatment. Nasopha- these are safely done. Unfortunately, there are no unim-
ryngeal airways lend themselves nicely to MAC or general peachable studies verifying this. Further, dentistry has no
anesthesia. Dilation with increasing sizes lubricated with institutional review of mortality and morbidity, so accu-
lidocaine gel works even if an endotracheal tube is not uti- rate statistics do not exist. The absence of professional
lized. Length is also critical when less than general anesthe- introspection perpetuates empirical practices. Empirical
sia is the goal. A too short nasal airway is useless, whereas evidence is sometimes dead on. For instance, legend has it
one that is too long can prevent a working environment if that the ¬rst de¬brillation of a human was done with the
a restless patient coughs or resists. energy levels “guessed” based on humans being between
Topical anesthetics (or local anesthetics) can help mice and horses in size. The “guess,” 350 joules, is about
with patient tolerance, but they have short action dura- what studies veri¬ed over time. Good guess! Sometimes,
tions. Additionally, the dental treatment requires an open the empirical observation is off the mark. G. V. Black, the
Special Needs of Cosmetic Dental Patients 53


“Father of Modern Dentistry,” is reported to have taught Monitors (and anesthesia equipment) are another area
that tooth brushing with a hard toothbrush, back and where state regulations play a large role for dental cases.
forth, after every instance of eating, leads to good dental All states currently have laws and/or regulations regard-
health. Black based this observation on those who prac- ing sedation and anesthesia for dental patients. As dis-
ticed this ritual. The hard toothbrushers had less dental cussed herein, these regulations are often very speci¬c.
disease than those who didn™t. He failed to notice those They often have lists of drugs, instruments, and electronic
who didn™t brush at all. . . ever! No control existed for monitors that must be present for various levels of anesthe-
those that brushed occasionally, brushed up and down, or sia. Sometimes the anesthesia levels are de¬ned; however,
brushed with implements other than a “brush.” The germ the de¬nitions may not be clear in the context of current
theory came later. Food proved much less a problem than therapeutics (see Appendix 1-1). Some states require mon-
the microbes. Hindsight can sometimes be amusing, as the itors to be ¬xed at the treatment site. Portable monitors,
Black anecdote illustrates. regardless of quality, do not qualify! Providing anesthesia
There are some published surveys available on for dental patients has to start with individual state regu-
anesthesia-related mortality and morbidity for dental lations. Be prepared to be surprised at what one may ¬nd
patients.20 In addition to being uncontrolled studies, they there.
contain inconsistencies that the trained observer ¬nds Most parameters are monitored exactly as they would be
curious. One such survey, the Perrott survey21 of oral sur- for any type procedure: pulse oximeter sensor on ¬nger or
geons published in 2003, has been criticized for method- ear, NIABP cuff on arm, cardioscope electrodes on chest,
ology and integrity. Also worrisome are some of the data BIS electrode on forehead, end-tidal CO2 in the circuit,
reported. Of 24,737 general anesthesia (GA) or deep seda- gas analyzer in circuit, and so forth. What if there isn™t a
tions (DS), 11,138 (or 45%) were done without contin- closed system? Many dental cases are done with open or
uous ¬‚ow (9,208 with no at all).21 Also interesting is semi-open systems. How can one monitor gases? A mon-
that 95.5% of the GA/DS were provided by an operator- itor with a pump (“side streaming”) for its CO2 and gas
anesthetist oral surgeon anesthesia “team.” The “team” bench only needs access to the patient to function. When
concept is described in the AAOMS guidelines22 as con- the circuit is not completely closed, the data is subject to
sisting of three people for GA/DS. However, the Perrott atmospheric corruption, but the “relative” value is still
et al. study reports a mean size anesthesia team of 2.7.21 worthwhile. Further, a waveform is created and the alarms
Another curious ¬nding was that 7.9% of GA/DS were can be used.
“awake.” If 7.9% of these anesthetics clearly failed, why Creative connections abound, but the use of an 18 ga
was the dissatisfaction rate only 1.1%? Most interesting was catheter (sans needle) placed in the nose or nasal air-
the Perrott et al.21 conclusion that a 1999 study reporting way and attached to the luer end of the sample tubing
a 1:1 million mortality rate and a later 2001 study report- gives a reasonably good result. Once placed, a dental of¬ce
ing a 1.28:1 million mortality rate proved that mortality nitrous-oxide/oxygen hood can be used over it. The result
provided by oral-maxillofacial surgeons (OMS) has been is comprehensive electronic monitoring without an ETT
decreasing.20 (see Figs. 5-2 and 5-3).
Every monitoring discussion requires a mention of the
precordial stethoscope. A heavy metal bell placed on the
MONITORING
neck in the sternal notch and attached to tubing and an ear-
piece or an electronic microphone provides real-time heart
Although there are many monitoring guidelines for anes-
and breath sounds. Commercially available radio trans-
thesia, the very highest level should always be employed
mitter and receiver devices provide high-quality audio
for each level of anesthesia care for all patients”including
and freedom of movement.23 In addition to the informa-
dental. There is no reason to provide less than the best.
tion, it provides redundancy because it is separate from
(See Chapter 18.) Modern electronics have made it pos-
a vital-signs or anesthesia monitor. A highly experienced
sible to monitor every parameter in practically any situa-
person can detect airway nuance and make a coarse anes-
tion. Monitoring can be portable, accurate, noninvasive,
thesia depth determination. However, no special training
and inexpensive.
54 James A. Snyder




Figure 5-3. Dr. Snyder maintaining a watchful eye on his patient.


is needed to obtain a bene¬t from the sounds. Coarsely
put: sounds are good”silence is bad.
Bispectral (BIS) monitoring24 is a recent development.
(See Chapter 3.) Monitoring the level of hypnosis is highly
valuable in anesthesia care. BIS is particularly useful for
of¬ce-based anesthesia. It makes it possible to achieve
amnesia reliably with less than general anesthetic tech-
nique. Careful skin preparation and placement of the
forehead electrode provides reliable values during any
anesthetic for all dental procedures.25,26 Most patient Figure 5-5. Dr. Snyder scans his monitors and anesthesia
machine.
monitoring results in safer, more precise anesthetics. Once
the learning curve is passed, BIS will do this. BIS pro-
ANESTHESIA TECHNIQUE
vides information not available from any other monitor-
ing device. Thoughtful use will result in decreased drug
Any modern technique will do nicely for dental patients.
use and faster wakeups and discharges.27 Best of all, it will
The basic formula (recipe) for anesthesia is as follows:
allow certainty of amnesia during the procedure. In the
hypnosis + analgesia + muscle relaxation
end, that is the one thing patients are absolutely, positively 1.
expecting. 2. add modern drugs to balance the formula
3. monitor all necessary parameters
4. use local anesthesia liberally
5. supervise 1“4 with anesthesia professional

The majority of anesthesia for dental procedures is deep
intravenous sedation without airway protection or venti-
latory support. Benzodiazepines in conjunction with opi-
oids have been favored by oral surgeons.28 Dentist anes-
thesiologists favor propofol with fentanyl, remifentanil,
or ketamine. Benzodiazepines are sometimes used supple-
mentally. Remifentanil is more safely delivered by infusion
pump.
In those instances where general anesthesia is planned,
after securing the airway, standard inhalation agents
are used for maintenance. Des¬‚urane offers very rapid
Figure 5-4. Dr. Snyder charting the anesthesia record.
Special Needs of Cosmetic Dental Patients 55


and ketorolac for analgesia.40 Other studies35,40 with po
emergence to eye opening, but time to discharge may not
be similarly shortened.29 clonidine premedication consistently demonstrate a 20%
reduction in propofol requirements.
The movement away from opioids, both for intraoper-
ANESTHESIA AND PAIN CONTROL OPTIONS
ative analgesia and postoperative pain management, has
Years of experience and studies too numerous to count recently hit a snag. The safety of COX-2 inhibitors has
have concluded the same thing: pain is bad. Pain slows been called into question, and some drugs in this class have
recovery.30 Absence of pain is nearly always the highest been withdrawn from the market. Inspection of the mech-
criterion (or lowest depending on one™s point of view) anism leading to this action suggests that more periph-
for patient satisfaction. Every patient believes the fee is erally acting analgesics such as NSAIDs will also come
too high regardless of what it is. However, a pain-free (or under scrutiny. Managing postoperative pain with pre-
much less pain than anticipated) experience usually yields and intraoperative anesthesia strategies may become crit-
a satis¬ed patient. The converse is also true: a near-perfect ical to patient comfort.
procedure can be highly underappreciated by a patient The use of opioid analgesics is alive and well in dental
having greater than anticipated pain. Patients seeking cos- practice. However, Moore™s recent survey of oral surgery
metic procedures seem particularly demanding of a pain- practice showed nearly 93% always or nearly always using
opioids as standard postoperative medication.28
free experience. Success in this practice requires mastery
of pain control. Pain complaints from lengthy dental procedures origi-
A thoughtful anesthesia plan can considerably decrease nate more often from temporo-mandibular joint and mas-
postoperative pain. Dentist researchers pioneered early ticatory muscles than from the treatment area. In¬‚am-
study of this area. The primary pharmacology tool for mation after prolonged near-maximum opening of the
studying oral analgesics is the “Cooper”Dionne third normally closed mouth is de¬nitely unpleasant. Mouth
molar extraction” model. Dionne31 demonstrated that the and face pain is tenacious. There is no way to rest or support
use of pretreatment ibuprofen coupled with long-duration a painful TMJ or massetter. Swallowing, speaking, eating,
local analgesia nearly eliminated postoperative pain med- drinking, even lifting, all result in jaw movement. Dex-
ication needs. Including local anesthetics during and at amethasone 8“10 mg IV immediately after induction, is
the end of surgical procedures minimizes neuronal “wind useful in reducing this in¬‚ammation and thereby the pain
up”32 and is now accepted practice. associated with it. Other steroid preparations, adjusted
Studies have shown that preoperative acetaminophen, for dose equivalency, may also be useful, but dexametha-
intraoperative low-dose ketamine, and intraoperative low- sone has favorable pharmacokinetics, phamacodynamics,
dose fentanyl have all reduced the need for postoperative and cost index. Dexamethasone, given early in the anes-
thesia, also reduces PONV.41,42 Two patient-satisfaction
analgesia. The use of clonidine as an anesthesia drug is not
new among plastic surgeons,33,34 but it has been getting issues addressed with one drug provides a win-win
more use by anesthesiologists recently.35 Alpha2 adrener- situation.
gic agonists may open an entirely new pathway for anes-
thesiologists. For instance, infusion of dexmedotomidine
POSTOPERATIVE NAUSEA
has been used as a sole agent for sedation.36
AND VOMITING (PONV)
Clonidine has been added to local anesthetics to
improve results of regional and epidural blocks for chronic If pain isn™t a patient™s highest (or lowest) satisfaction
pain or postoperative pain relief.37,38 Oral clonidine 0.4“ criterion, PONV certainly is. Pain or PONV can make
0.5 μg · kg’1 taken ninety minutes prior to induc- everybody unhappy with the postoperative period. Mis-
tion reduces drug needs for sedation or general anes- ery and low satisfaction aren™t the only issue with PONV.
thesia35,39 and reduces postoperative pain medication It can reduce the outcome of many cosmetic procedures,
requirements.39 A recent study demonstrated low pain, including dental ones. Because the mouth is the primary
low nausea and vomiting, and high satisfaction with exit portal in vomiting, dental procedures are especially
general anesthetics using clonidine, low-dose ketamine, vulnerable to the damages caused by vomiting. Implants,
56 James A. Snyder


bone grafts, periodontal plastic surgery, jaw surgery, and VENUE SELECTION
extractions will all be adversely affected by vomitus. Out-
Treatment outside a hospital has always been popular for
come is reduced, pain increased, and the misery factor
cosmetic procedures, and the of¬ce is the primary location
multiplied”a lot of badness.
for dental care. The location where a procedure is done has
Another unique requirement of dental procedure anes-
little to do with successful outcomes. Complex surgeries
thesia is that treatment in the mouth increases the like-
are successfully done on battle¬elds, makeshift operating
lihood of PONV. Treatment site bleeding or oozing is
rooms, and in many unusual locations. Good cosmetic and
swallowed, detritus from treatment including organic and
dental results have been achieved for millions outside hos-
inorganic dust is swallowed (or possibly aspirated), treat-
pitals. The critical ingredient is the training, experience,
ment often produces edema, prolonged oral opening and
and ethics of the professionals involved in the treatment.
manipulation can result in tongue and pharynx edema,
Dental procedures require special and unique instru-
and dental treatment involves really bad (or worse) tasting
ments, materials, and procedures. Few hospitals or stand-
materials. These are all PONV provocateurs.
alone surgery centers are properly equipped. There are
With all treatment occurring in close proximity to the
many obstacles. Hospital operating rooms are typically
airway, periods of hypoventilation are likely unless a closed
arranged for the surgeons and their assistants to be stand-
airway system is employed. Periods of elevated PaCO2 can
ing. Dental treatment is almost universally provided while
lead to PONV. Most dental anesthetics do not employ ETT
sitting.
or other closed-airway-system devices. For instance, oral
Dental treatment requires a lot of little x-rays that can-
surgeons provide the majority of dental anesthetics and
not be exposed accurately with hospital x-ray units. Even
rarely use ETT.20
a “dental friendly” operating center can stock only a very
Underhydration, intraoperative opioid use, oxygen
limited number of dental supplies and materials.
desaturation, prolonged high nitrous oxide concentra-
There are many, many materials suitable for almost any
tion, early ambulation, hypoglycemia, and postopera-
dental procedures. The technical nuances of using the
tive opioids have all been implicated in PONV. All of
materials differ from product to product. Suboptimum
these factors can be common, if unintentional, occur-
outcomes are more likely with dentists using unfamiliar
rences in dental cases.43 In preventing pain and PONV
or inexactly selected materials.
for cosmetic procedures, an ounce of prevention truly
There are some devices so unique they are unlikely to
is worth a pound (or with in¬‚ation these days, a ton)
be found outside a dental of¬ce, for example, a ceramic
of cure. A thoughtfully crafted anesthesia plan begins
glazing oven, impression mixing machines, and den-
prior to induction and extends for twenty-four hours.
tal lasers. The latest cosmetic materials and techniques
For instance, techniques using minimal opioids, good
often require unique equipment and materials. Treatment
hydration, adequate alveolar ventilation, and thought-
options shouldn™t be “square pegged” by a facility™s “round
ful recovery techniques will minimize the ¬rst nausea
hole.” Finally, dentists, like most professionals, are most
episode. Reducing or eliminating opioids from the anes-
comfortable where they are most familiar. If they do not
thesia technique looks like a good idea when considering
regularly visit a treatment site outside their own of¬ces,
the PONV concern. Remifentanil is the only exception at
they may not be as ef¬cient.
this time. However, its rapid elimination and favorable dis-
tribution characteristics provide negligible postoperative
CONSUMER DUE DILIGENCE
analgesia.
All antiemetics have vastly superior success rates when Most cosmetic procedures require a considerable ¬nan-
administered before PONV as opposed to their use as a cial commitment from the patient. Patients usually invest
“rescue” therapy. This includes the newer 5-HT3 inhibitors considerable time and resources selecting a dentist to give
as well as older drugs. The ReliefBand r electric stimulator them the very best outcome possible. Comfort is usually
device works well when used in advance of an episode. Even a part of the calculation. Finding a compatible anesthesia
the lowly OTC drug, meclizine, is effective if given well in provider to complement the procedure must be part of the
advance of the potential triggering events. equation.
Special Needs of Cosmetic Dental Patients 57


Questions to ask of the anesthesia provider are the 2. American Dental Association: ADA Council on Dental Edu-
cation. Part Two: Guidelines for teaching the comprehensive
following:
control of pain and anxiety at the advanced education level.
Chicago: First adopted May 1971; reviewed October 2003.
1. Is this true “conscious” sedation? (Which means I
3. American Dental Board of Anesthesiology: The ADBA
will be lightly sedated, still respond to verbal com- Mission. Available at www.adba.org/mission.html. Accessed
mands, and be able to breathe normally without June 14, 2005.
4. American Dental Association: ADA Council on Dental Edu-
snoring.)
cation. Accreditation standards for advanced specialty edu-
2. Is this a deep sedation technique? (I will not respond
cation programs in oral and maxillofacial surgery. Chicago:
to verbal commands and I may need some airway Adopted October 1990; reviewed 1998.
support, e.g., chin lift, mechanical airways.) 5. Field M, ed.: Dental education at the crossroads: Challenges
and changes. Washington, DC: National Academy Press;
3. Will I be given general anesthesia? (Will I be com-
1995.
pletely asleep? The intravenous medications may be
6. Florida Statue Title , Chapter 466, Section 0285.
supplemented with an inhalation anesthetic, and a 7. American Society of Anesthesiologists: Guidelines for of¬ce
type of arti¬cial airway will probably be used, e.g., based anesthesia. Reviewed 2000. Available at www.asahq.
org/publicationsAndServices/of¬ce.pdf. Accessed June 21,
endotracheal tube [breathing tube], LMA.)
2005.
4. Who will monitor me during the procedure? 8. Diogo S: Reconcilable differences?: Dental, medical educa-
5. Will this person have any other responsibilities tion remain at odds. AGD Impact 28:14,2000.
9. American Psychiatric Association: Diagnostic and Statisti-
beside the anesthetic? (The answer should be “no.”)
cal Manual of Mental Disorders, 4th ed., text revision. Sec-

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