General Principles

Patients typically present to an ambulatory surgical center for anesthesia and subsequent reconstruction the day of their Mohs procedure, usually without any prior medical screening. Often patients are added to the operating room (OR) schedule late in the day after the dermatologist has completed the procedure and decided that the patient would be best served by closure in the OR by a plastic surgeon, as opposed to immediate closure in the dermatology clinic. Anesthesia providers must then determine if the patient is an appropriate candidate for anesthesia, what type of anesthesia, such as general endotracheal anesthesia (GETA), monitored anesthesia care (MAC), or local anesthesia with or without conscious sedation, the type of operative facility (outpatient vs. hospital), and if the patient has an empty stomach (meets American Society of Anesthesiologists NPO [nihil per os] guidelines). ¹

Patients for repair of facial Mohs defects should receive a preoperative phone call prior to their Mohs procedure. This phone call is to identify any major medical issues that should delay the procedure if more medical workup will be necessary. Patients are not all sent for routine pre-op testing. Standard preoperative laboratory testing has proven to not be cost-effective and can lead to false-positive results and surgical delays. Additionally abnormal laboratory results have not been shown to have a correlation with perioperative complications. ² The exception to this is pregnancy testing in females younger than 50 years, and this should be standard on all female patients who have not had a hysterectomy. The prognostic value of preoperative electrocardiograms has also not been proven. These can be done at the discretion of the provider in most patients who pass the preprocedure phone call on the day of the procedure. Anesthesiologists also vary in their decisions on which electrocardiogram (EKG) abnormalities warrant further evaluation, therefore again bringing into question the benefit of pre-op EKGs in most patients.

On arrival to the surgical facility, the preoperative assessment includes NPO status, baseline cardiac rhythm, blood glucose level in diabetic patients, use of anticoagulants, regular medicines including the time of last B blocker dose, room air oxygen saturation, routine medicines, examination of the airway, BMI (body mass index), and any other coexisting medical issues. Often the morbidly obese are better served in the hospital setting if requiring anesthesia as narcotics will exacerbate sleep apnea issues and these patients may require longer postanesthesia recovery times. Patients having any IV (intravenous) anesthesia must be able to lay flat without supplemental oxygen.

2.2 Types of Anesthesia

The type of anesthesia used for each patient for the reconstruction of the Mohs defect will depend upon the type of defect to be repaired, the preference of the surgeon and patient, the patient’s current presenting issues and preexisting medical problems, and whether the procedure is elective versus emergent or urgent. Occasionally facial reconstructive patients will be added to the surgery schedule without confirmation of their ride home or NPO status. If the patient has driven himself and does not have another option for transport after procedure, or if the patient is not NPO, the surgeon will need to decide if this is a case that should be delayed or can be accomplished with straight local anesthesia. Likewise, if the patient has significant medical comorbidities making the prospect for safe anesthesia questionable, then the patient might proceed with straight local anesthesia, be transferred to an inpatient facility, and/or be delayed for medical workup and clearance. Assuming the surgery will proceed with anesthesia, the patient may be consented for either MAC or general anesthesia (GA).

2.2.1 Monitored Anesthesia Care

The ASA defines MAC as a specific anesthesia service in which an anesthesiologist has been requested to participate in the care of a patient undergoing a diagnostic or therapeutic procedure. ³ The role is to monitor vital signs while administering anxiolytics or analgesics for patient comfort. Sometimes no anesthetics are given, but the anesthesia provider monitors patient’s vital signs and treats them as necessary. MAC can encompass differing depths of sedation and may be termed conscious sedation as the patient should be able to respond to verbal or tactile stimuli. Healthy patients should be able to maintain their own airway and are unlikely to have any cardiovascular compromise from the sedatives. A patient with significant comorbidities may have hemodynamic changes from minimal sedation. Once a patient is not responsive and/or is unable to maintain an unobstructed airway, the terminology changes to deep sedation and GA. GA is a drug-induced loss of consciousness during which patients are not arousable, even by painful stimulation. These patients are likely to require airway support and may be subject to cardiovascular changes.

For patients with small facial defects, or in patients with significant comorbidities, minimal sedation may be all that is required. These patients are consented for MAC, told they will not be completely asleep, and are likely to have recall of the OR. All patients must have an IV when entering the OR, even if not being sedated, as injection of local anesthesia with epinephrine may cause significant changes in hemodynamics that may require rapid treatment. Most patients receive a benzodiazepine, namely midazolam, prior to leaving the preoperative area. Midazolam is a sedative and has rapid onset of anxiolysis with minimal side effects and causes anterograde amnesia, but no analgesia. At low doses (0.02 mg/kg), midazolam is an effective anxiolytic over a wide age range (20–80 years), with minimal respiratory depression in healthy patients. Larger doses (0.05 mg/kg) increase the likelihood of sedation but are not more effective at relieving anxiety. ⁴ Because elderly patients may have increased postoperative sedation, especially those with preoperative cognitive deficits, midazolam is often withheld in this patient population.

Patients for sedation may also receive IV fentanyl. Fentanyl is ideal because it is a rapid-onset, short-acting opioid that produces analgesia. It has a shorter half-life than morphine sulfate, thus having the benefit of quicker arousal time. It can also decrease anxiety by decreasing pain, a common preoperative issue in patients with new facial defects who have arrived from dermatology. Fentanyl is easy to titrate and easily reversed by naloxone. Midazolam and fentanyl act synergistically. The analgesic and respiratory effects of fentanyl are pronounced in the presence of midazolam, it can depress the respiratory drive, and the anxiolytic and sedative effects of midazolam are pronounced in the presence of fentanyl. ⁵

The anesthesia provider must be prepared to treat hemodynamic changes that may occur during a procedure in which the patient is only receiving sedation. He must also have a plan for respiratory depression as the depth of anesthesia may change resulting in an unexpected unconscious patient. Emergency airway equipment must therefore always be available.

MAC patients are brought into the operating suite on a stretcher with a separate head attachment, which cradles the head during the procedure (▶ Fig. 2.1). They remain on this same stretcher from pre-op through the OR and recovery area until discharge. On entering the room, standard ASA monitors are placed: EKG, pulse oximeter, and blood pressure cuff. They are given oxygen through nasal cannula during the time of injection of local anesthesia by the surgeon. The oxygen cannula is usually removed prior to the prep solution being placed on the face. The preprocedure oxygen is removed not only because the nasal cannula may possibly obstruct the operative field, but also because an open system of oxygen cannot be on the face due to the high risk of fire sparked from an electrocautery device in an oxygen-rich environment. These patients are continually monitored for changes in hemodynamics as well as level of sedation. More sedatives can be given if deemed necessary. These patients are generally awake on arrival to the postanesthesia care unit (PACU) and are ready for discharge in 30 minutes.

2.2.2 General Anesthesia

Patients requiring skin grafts, local flaps, and complex closures typically receive IV GA. These patients are consented for GA because loss of consciousness is anticipated. This is explained to the patient during the preoperative interview and that invasive airway devices are not anticipated. Premedicating for prophylaxis for gastric content aspiration should be considered. Metoclopramide is sometimes used both as a motility agent, to lessen the likelihood of aspiration, and as an antiemetic. Patients may experience agitation or anxiety when metoclopramide is used as a rapid IV bolus, and less commonly extrapyramidal reactions can occur. Other gastric acid reducing agents often considered are H₂ blockers such as famotidine, proton pump inhibitors such as omeprazole, and sodium citrate, Bicitra. Aspiration of stomach contents can have such devastating consequences that patients having anesthesia without a secured airway should be carefully considered for prophylaxis.

All patients having Mohs reconstruction should receive IV antibiotics. For patients having IV GA, a benzodiazepine (midazolam) is administered en route to the OR. Most often, the facial reconstructive patients have been in a medical facility for hours by this point and are hungry and anxious for completion of surgical repair. Therefore, anxiolysis is appropriate for most patients and makes them more comfortable about entrance to the OR. Once in the operating suite, the patient remains on the transport stretcher that has the additional headrest and oxygen by nasal cannula is administered. ASA monitors—EKG, pulse oximetry, capnography via the oxygen cannula, and blood pressure cuffs—are placed on the patient and monitoring begins. When the surgeon is ready to inject local anesthesia IV lidocaine is given followed by a slow injection of propofol to maintain the respiratory drive and render the patient unconscious. By keeping the patient unconscious during injection of the local anesthesia, the patient’s blood pressure and heart rate should remain controlled, decreasing bleeding from the surgical site. Hemodynamic stability is important in any patient, but especially in patients with cardiac disease. The eyes are lubricated with ophthalmic ointment to protect them from irritation from the prep solution. After the patient can maintain an open airway, the supplemental oxygen is removed. This is always done prior to the facial prep as a reminder to keep the open flow of oxygen off the surgical field. If the patient is stable on room air and uncomfortable, or at surgeon preference, additional sedation with propofol can be administered by small incremental boluses or by infusion during the procedure. As propofol is short acting, these patients are typically awake by the end of the procedure or shortly after arrival in the PACU and are discharged without incident within 30 minutes.

Patients having midline forehead flaps or other more complicated procedures are administered general inhalational anesthesia. GA helps ensure a calm operating environment without patient movement. This begins with IV midazolam and antibiotics on the way to the OR. Patients remain on the transport bed with the headrest (▶ Fig. 2.1), and standard ASA monitors are attached. Preoxygenation is initiated via face mask. The type of airway chosen is based on the surgical site and patient factors. If the facial defect is on the nose and therefore there is likelihood of blood in the airway, an endotracheal tube is chosen. If the defect is cheek, forehead, scalp, or any other area where blood in the mouth is unlikely, a laryngeal mask airway (LMA) can be used. Anesthesia is routinely induced with IV fentanyl and an induction agent. Propofol is most commonly used and is given with IV lidocaine first to decrease the venous irritation that is felt as propofol is started in the IV. The amount of lidocaine can vary, but the anesthesia practitioner should be cognizant of the fact that the plastic surgeon will be adding local anesthesia at the site and the amount of total local anesthesia should be considered to avoid local anesthetic toxicity. Etomidate can be used as an induction agent, particularly in patients with significant cardiovascular disease. Etomidate is a mild cardiovascular depressant and blood pressure is only minimally affected as compared with propofol. After the patient is unconscious, an LMA can be placed if appropriate, or a neuromuscular paralyzing agent can be given and the airway secured with an endotracheal tube. In most situations, an oral Ring–Adair–Elwyn (RAE) endotracheal tube is used to avoid being in the way of the surgeon. This tube also does not need to be secured as it should stay in place at the curve, making mobility of the tube possible for the surgeon. Lubrication is placed in the eyes prior to the prep and the eyes are covered or secured in the field. If the patient has an LMA, the goal is resumption of spontaneous ventilation of an inhalational agent. If paralyzed and with an endotracheal tube, the patient is put on the ventilator and given an inhaled anesthetic in conjunction with an oxygen and air combination. Sevoflurane and desflurane are the most commonly used volatile anesthetics. Their low blood and fat solubilities allow more rapid awakening compared to isoflurane. Additional narcotics and neuromuscular blockers are added as deemed necessary.

Patients who are maintained on a volatile anesthetic are given prophylaxis for prevention of postoperative nausea and vomiting (PONV). Corticosteroids, primarily dexamethasone, are given shortly after induction. These medicines have both the benefit of reducing facial and airway swelling, and also are an effective prophylactic against PONV. Ondansetron, a serotonergic receptor antagonist with minimal side effects, is widely used 30 minutes prior to arousal.

At the conclusion of the surgical procedure, the LMA is removed with the gas on to avoid the patient biting on the LMA and to ensure the patient does not move during removal of the artificial airway. After suctioning a patient with an endotracheal tube and little to no blood is in the airway, the endotracheal tube can also be removed with the gas on and the patient under deep anesthesia—a “deep extubation”—by an experienced anesthesia provider who is comfortable with deep extubations. The benefits to this are to avoid coughing and bucking during emergence causing hypertension in the face with added risks of additional bleeding or wound dehiscence.

Hemodynamic changes intraoperatively are common and the anesthesia provider needs to be prepared to intervene pharmacologically to correct any hemodynamic instability such as blood pressure changes and dysrhythmias. Severe intraoperative hypotension is an anesthetic emergency. Prompt recognition and treatment is vital to ensure organ blood flow, particularly to the brain, heart, and kidneys. Propofol produces vasodilation in both the arterial and venous circulation, producing a significant decrease in systemic blood pressure. Both sevoflurane and desflurane also reduce systemic vascular resistance and blood pressure, especially in the face of volume depletion due to fasting or bleeding. Hypotension intraoperatively can be lessened by decreasing the concentration of inhaled anesthetic and increasing the infusion rate of IV fluids. Boluses of ephedrine and phenylephrine are most commonly used to treat hypotension intraoperatively. Ephedrine is a sympathomimetic that has both alpha and beta activity and is used for treatment of vasodilatory hypotension. It generally raises the heart rate as well. Phenylephrine exhibits potent vasoconstriction via alpha 1 receptors, which causes a rise in blood pressure as well as a reflex bradycardia. Treatment of hypotension should be swift because if left uncorrected, it can lead to stroke, myocardial infarction, and acute tubular necrosis.

Severe intraoperative hypertension also requires immediate intervention to prevent CNS (central nervous system), cardiac, and renal adverse effects. In facial surgeries, even slightly elevated blood pressure will cause bleeding at the surgical site, making the success for the desired result less likely. The most commonly used medications to lower intraoperative blood pressure are hydralazine and labetalol. Hydralazine is given in bolus dosages to cause arteriolar vasodilation. It can cause a reflex tachycardia. Labetalol has a combined alpha and beta receptor antagonist effect and thus lowers blood pressure and heart rate. Changes in heart rate without significant blood pressure alterations can also occur. Glycopyrrolate or atropine can be bolused to raise heart rate. Metoprolol or esmolol, beta blockers, lead to rapid control of tachycardia.

The most commonly uses local anesthetics are the amides (lidocaine and bupivacaine). Local anesthetics act by blocking sodium channels and may be used with or without epinephrine. Bupivacaine (Marcaine) can last up to 8 hours and it is longer acting than lidocaine, which lasts 1 to 2 hours (▶ Table 2.1). The addition of epinephrine to all local anesthetics causes veins to constrict, helping with hemostasis, prolonging the anesthetic effect. Local anesthetic toxicity is a rare but serious potential intraoperative event. High plasma levels of local anesthetics affect organs that are dependent on sodium channels to function. Most cases of toxicity result from accidental intravascular injections. Less likely, but possible, is absorption of a significant amount of local anesthetic from the surgical site. The lidocaine injected intravenously prior to propofol should also be considered when figuring maximum dose of local anesthesia allowable in a patient. Toxicity can lead to serious CNS and cardiovascular complications. CNS toxicity manifests on a continuum starting with oral numbness and foul taste, to vertigo, tinnitus, and in severe cases seizure. Seizures should be treated with supplemental oxygen and a benzodiazepine. Refractory seizures may require induction of GA and invasive airway support. Cardiovascular repercussions from the blockade of sodium channels can progress from myocardial depression, heart block, ectopy, arrhythmias, and ventricular fibrillation. Bupivacaine is the most cardiotoxic of the local anesthetics because it binds the most tightly to the sodium channels. Treatment of cardiac symptoms is supportive with oxygen, vasopressors, inotropes, and antiarrhythmics. Additionally, lipid emulsion therapy should be instituted promptly when there are signs of hemodynamic instability suggesting impending cardiac collapse. Lipids are given by an initial bolus followed by an infusion until at least 10 minutes after the patient regains hemodynamic stability.

2.3 Recovery

Because of local infiltration by the surgeon, most patients in the PACU after Mohs reconstructive surgery have little to no pain. Patients with mild postoperative pain in whom postoperative bleeding is not a concern can be treated with oral or IV nonsteroidal anti-inflammatory drugs. Oral or IV acetaminophen is also often an appropriate choice. Patients receiving acetaminophen should be counseled about acetaminophen dosing after discharge so as not to exceed the Food and Drug Administration (FDA) recommended 4 g/d limit. For patients with more significant pain, for example, headache in a forehead flap patient, IV narcotics are reasonable. Oral narcotics on an empty stomach are less desirable at this time because of the increased risk of nausea after anesthesia, especially before transport home. In a patient who may have swelling or discomfort around the eyes, a cold gel mask is often applied. These masks are reusable and replaced with a fresh cold mask intermittently. The patient can take these home in a box set and keep them in the refrigerator to exchange periodically during the recovery period (▶ Fig. 2.2).

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Skin Graft Revisions Full-Thickness Skin Grafts Forehead Reconstruction Local Flap Revisions Ear Reconstruction Split-Thickness Skin Grafting

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