Introduction

General anesthesia (GA) remains the most common form of anesthesia provided for elective surgery. It is safer than ever. However, when current neurophysiologic monitoring is applied (in an off-label use), we have found that the safest achievable anesthesia available is brain-activity monitored, propofol/ketamine (PK), monitored anesthesia care (MAC), intravenous (IV) sedation. “Safer than ever” GA is less acceptable when “safest achievable” PK anesthesia can be had with little additional effort and improved cost-effectiveness. Especially in the postbariatric patient, the anesthesia emphasis must always be on maximum safety first. As has been elucidated in the preceding chapters in this textbook, these patients differ from other surgery patients both anatomically and physiologically.

These patients are not “sick” in the sense that most physicians understand the term illness. Their issue is what they see in the mirror, as well as what the surgeon observes during the preoperative visit. Their concept of a successful surgery is not only the elimination of illness but an improvement in their symptoms as well as in their perception of their own appearance.

Post–bariatric surgery patients, especially those undergoing cosmetic procedures that are not associated with functional disability, are also more apt to complain about the kinds of discomfort the typical surgical patient would not complain about: intravenous catheters, cold sheets, and inattentive staff. To them, their surgery is every bit as serious as open-heart surgery.

Postoperative nausea and vomiting (PONV) is often described by anesthesiologists as a big “little” problem.1 For the post–bariatric surgery patient, PONV is a big problem. If an abdominoplasty patient experiences PONV, the resultant intraabdominal pressures can produce hematomas or rupture the sutures vital to the success of these operations. With severe emesis, rupture of the esophagus has even been reported.

Bispectral (BIS) index–monitored PK anesthesia has enabled patients to enjoy an essentially PONV-free surgery without the use of any antiemetics.2 One of the authorities on PONV, Christian Apfel,3 authored the first chapter in Miller’s Anesthesia, 7th edition, dedicated to this persistent, unpleasant side effect of anesthesia. Apfel endorses PK anesthesia as essentially a non-emetogenic technique. Apfel also states that as long as inhalational agents like isoflurane (Forane), sevoflurane (Ultane), or desflurane (Suprane), or intravenous opioids like fentanyl (Sublimaze), alfentanil (Alfenta), or remifentanil (Ultiva), are given as part of anesthesia, antiemetics are of limited value in preventing PONV.3

Postoperative pain remains a problem for many patients receiving other non-PK anesthesia, despite the fact that preincisional local analgesia with epinephrine was commonly administered.4 PK anesthesia patients also receive preincisional local analgesia with epinephrine, yet rarely do they experience problematic postoperative pain. Something very different is being provided with the PK anesthesia paradigm: preemptive analgesia.

BIS monitoring with electromyography (EMG) as a secondary trace helps the surgeon determine when to inject more local anesthetics while the patient is asleep at the beginning of the procedure as well as during the procedure, precluding the need for GA. Since adopting routine BIS monitoring in 1997, PK anesthesia patients have not required any opioids for postoperative pain.5

Although malignant hyperthermia (MH) is rare, on March 28, 2008, two patients died of it. The first was a college-bound, Boca Raton, Florida, teenager, and the second was a 2-year-old child in Long Beach, California. The Boca Raton death received national media coverage for days. The Long Beach death never even made it to the local papers. What accounted for the difference The Boca Raton patient was having elective cosmetic surgery, whereas in Long Beach the infant was having a medically indicated procedure. Anyone who provides office-based anesthesia for cosmetic surgery patients should at least consider the virtues of brain-monitored PK anesthesia.

Lesser physiologic trespass translates into greater patient safety. Since 1992, there have been no deaths or major complications reported with PK anesthesia. Clayman and Seagle6 also support the patient safety of ketamine anesthesia, citing the collective multidecade experiences of Vinnik,7 Ersek,8 and Gruber and Morley.9

Propofol has been a generic for several years. Thus, the cost-effectiveness of PK anesthesia is excellent compared with GA. Patient satisfaction with PK is very high, especially in patients who have had difficulty with PONV, prolonged emergence, or postoperative pain. Brain-monitored (e.g., BIS) PK MAC provides patients with many of the advantages of GA, including the ability not to hear, feel, or remember the surgery, without many of the risks and unpleasant side effects of GA.

What Is Anesthesia

Anesthesia = Hypnosis + Analgesia

First and foremost, anesthesia is a reversible state. Second, anesthesia is the sum of two components: sleep (hypnosis) and pain relief (analgesia). Contained within the concept of hypnosis is amnesia. Contained within the concept of pain relief in plastic surgery is an adequate degree of analgesia that permits muscle relaxation sufficient for subpectoral muscle dissection or rectus sheath imbrication without resistance.

Although relatively simple to use, brain-activity monitors measure only the hypnotic component of anesthesia. There are currently no monitors that specifically measure the anal-gesia portion of the anesthesia equation. However, the EMG as a secondary trace with BIS may be used to differentiate spinal cord (nonpurposeful) patient movement from cerebral cortical (purposeful) patient movement. Appropriate therapy for each type of movement may intelligently then be applied.

Patient movement with hypnosis at adequate levels of brain activity (i.e., 60 to 75% of awake values) and in the absence of EMG activity should be interpreted as spinal cord level (nonpurposeful) movement, and therefore devoid of the implications of awareness or recall.10 (A chicken can run around without its head; thus the brain is not required for body movement.) Inhalational agents like sevoflurane, desflurane, and isoflurane and intravenous agents like propofol (Diprivan) and methohexital (Brevital) act primarily on the cerebral cortex and are well measured by brain-activity monitors. Benzodiazepines like midazolam (Versed), diazepam (Valium), and lorazepam (Ativan) act primarily on deeper brain structures and are not well measured by current brain monitors.11 Intravenous opioids such as fentanyl, alfentanil, and remifentanil may produce secondary effects on these devices but also are not well measured by current brain monitors.12

When inhalational agents are administered, both hypnosis and analgesia are simultaneously delivered to the patient. GA has been numerically defined as 45 to 60% of awake value.13 End-tidal carbon dioxide (EtCO₂) is a standard of care for monitoring GA ( Table 5.1 ).

When measurable intravenous agents, such as propofol or methohexital, are administered, hypnosis at 45 to 60% of awake value with systemic intravenous analgesia may also define an intravenous general anesthetic. End-tidal CO₂ remains a monitoring standard of care independent of the inhalational or intravenous nature of the anesthesia.

Measurable intravenous agents titrated to 60 to 75% of awake value and local analgesia without systemic analgesia do not meet the threshold to define GA.13 In these cases,

EtCO₂ may be used to display a respiratory wave form but is not currently a standard of care. This type of anesthesia has previously been defined as either moderate or deep sedation, depending on whether passive or active airway intervention is required to maintain airway patency.5

Safety Issues

Airway

Without question, the airway and its management have been the greatest source of safety concerns for all patients. Over the past 30 years, the pendulum of anesthesia preference has swung back and forth between IV sedation and GA, depending on the available drugs, monitors, techniques, and anesthesia providers. In the 1970s, the only available intravenous agents depressed the patient’s respiratory drive and laryngeal reflexes, with the exception of ketamine.

Pulse oximetry (SpO₂) was not commercially available until 1984, and EtCO₂ not until the late 1980s. When hypoxemia occurred, patients were perceived as “restless” under the drapes and were given even more depressant medications. When their respiratory acidosis grew to intolerable levels, cardiac arrest was irreversible, and deaths became inevitable. GA with endotracheal intubation subsequently gained favor over IV sedation.

Propofol (Diprivan, Zeneca) was introduced in North America in 1989. Brain-activity monitoring became commercially available in 1996. Five years later, the 19-fold variability of propofol metabolism between individual patients was established.14 The implications of this metabolic variation confirmed the clinical observations of many practitioners of the wide variation in the propofol requirements between patients. No formula or algorithm based on body weight or calculated blood concentration could account for such a variation.

The study by Court et al14 in 2001 provides the most compelling rationale for monitoring individual patient responses to propofol administration. By incrementally titrating propofol (i.e., using small amounts sequentially as opposed to a single body weight–determined bolus) to a level approximately 70 to 75% of awake values with a brain monitored, one can avoid creating a difficult airway with induction.15

The laryngeal mask airway (LMA) insertion, especially useful in rhinoplasty, serves two purposes. First, it serves as an “umbrella” for the trachea, preventing laryngospasm from blood or debris falling from the posterior nasopharynx into the glottic chink. Second, it occludes the esophagus, preventing blood from entering the stomach and causing PONV. The flexible version is used so that it may be taped to the chin to get the tube out of the operating angle of the surgeon.

The patient in Fig. 5.1 graphically demonstrates the lack of change in the level of hypnosis with the insertion of an LMA device to maintain airway patency with BIS/PK MAC. Without such a change in hypnotic level or the addition of systemic analgesia, the insertion of an LMA per se in BIS/PK MAC anesthesia does not meet the definition of “general anesthesia.” The mere insertion of an LMA for airway patency does not transform BIS/PK MAC from IV sedation (class B) to GA (class C).

Newer techniques for intravenous sedation that include the use of propofol drips, often in combination with other drugs, have made it possible to perform lengthy or extensive surgeries without GA or the loss of the patient’s airway protective reflexes.5,16

Related posts:

4 Anesthesia and Safety Considerations in the Perioperative Period 7 The Anatomy and Chronology of Body Sculpting: Areas Requiring Correction and Timing of Procedures 6 Factors Impacting Thromboembolism after Bariatric Body-Contouring Surgery 8 Total Body Lift Surgery 9 Postoperative Pain Management Following Body Contouring 36 Facial Rejuvenation: Open Technique

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