Perioperative Monitoring in Obstructive Sleep Apnea/Hypopnea Syndrome

2.1

Selection of a Surgical Facility

The surgeon must select an operating room with personnel and equipment adequate for an elective and controlled management of the patient's airway. Preoperative preparation is intended to improve a patient's medical status and reduce the risk of complications. The literature is insufficient to offer guidance regarding which patients can be safely managed as an outpatient as opposed to an inpatient basis or the appropriate time for discharge from the surgical facility. Although there have been many review articles and position statements published citing the increased risk of surgery in patients with OSAHS, most of their recommendations for outpatient versus inpatient treatment have been based only on a consensus of opinions. In contrast, a study in Sweden on 4876 patients undergoing OSA surgery between 1997 and 2005 found no deaths within 30 days of surgery. The complication rates were 3.7% after UPPP, 0.56% after UPP, and 0.88% after nasal surgery (mostly bleeding or infection). Similarly, a study of data on 91,028 adult inpatients undergoing bariatric surgery from 2004 to 2008 obtained from the US Nationwide Inpatient Sample database found that sleep-disordered breathing was associated with decreased mortality, total charges, and length of stay.

Upper airway surgery in sleep apnea patients can temporarily worsen the sleep apnea and lead to serious and potentially fatal complications, including acute upper airway obstruction, hypoxemia, hypercarbia, myocardial infarction, cardiac arrhythmias, stroke, and death. Prevention of these complications requires early detection of pending airway problems. Postoperative monitoring is performed to detect and prevent potential complications. Although there are insufficient published data, it is assumed that patients with more severe sleep apnea are at greater risk for perioperative complications.

The determination to perform surgery as an outpatient; in an outpatient surgery center with ambulance transfer to a hospital facility; admit for a short extended recovery room stay; or admit to a 23-hour unit, regular hospital room, or an intensive care unit (ICU) should be made with consideration of associated comorbidities, severity of apnea, sites of airway narrowing, type of surgery and anesthesia, length of surgery, patient's age, need for postoperative opioids, and the capability of the outpatient and inpatient facility. This determination should be made preoperatively. The 2014 updated guidelines from the American Society of Anesthesiologists (ASA) used a scoring system to determine perioperative risk of complications, which suggested that any OSA patient undergoing airway surgery under general anesthesia was at increased risk of complications, unless using perioperative continuous positive airway pressure (CPAP).

Although care should be taken in selecting patients for outpatient procedures, it is clear that most airway surgery for OSA can be done safely as an outpatient. If the sleep apnea is severe, however, a longer observation may be required before discharge. The importance of the postoperative observation period is to document the presence or absence of sleep apnea and oxygen desaturation while sleeping without supplemental oxygen, normal vital signs (including blood pressure), adequate pain control, and ability to swallow.

2.2

Choice of Anesthesia Technique (Local, General, or Monitored Anesthesia Care)

The literature is insufficient to evaluate the effects of different anesthetic techniques on surgical outcomes after surgery for OSAHS. Because airway reconstructive surgery for sleep apnea causes blood to enter the airway, it is probably safest to perform these surgeries under general anesthesia to control and protect the airway. When a patient with OSAHS is undergoing non–airway-related surgery, then a local anesthesia or monitored anesthesia care would be preferred. If the patient is to undergo any sedation during a nonairway surgery, then both pulse oximetry and end tidal CO ₂ monitoring should be used. General anesthesia with a secure airway is preferred if the patient is going to require any extended procedure requiring moderate or deep sedation.

2.3

Use of Continuous Positive Airway Pressure (CPAP)

There is an alteration of sleep architecture and frequently sleep deprivation before and after surgery, including sleep deprivation due to anxiety about the surgery. Several days after surgery, however, the patient is more likely to have a rebound of stage N-3 and rapid eye movement (REM) sleep and may be predisposed to more severe sleep apnea. It would therefore seem to be beneficial to improve sleep quality as much as possible before and after surgery. When possible, a patient should be asked to use CPAP or their sleep oral appliance for several weeks before and after surgery and to bring their machine or appliance into the hospital for perioperative use. Although the majority of patients are undergoing surgery because they cannot tolerate CPAP/oral appliances, even moderate use of them preoperatively may be beneficial. Preoperative use of CPAP has been shown to reduce surgical complications in non–sleep apnea surgeries. CPAP is contraindicated preoperatively only in rare circumstances, such as in a patient with cerebrospinal fluid leak into the nasal airway.

2.4

Use of Narcotics and Sedative Agents

Use of narcotics, sedative hypnotics, and anxiolytic agents should be avoided before surgery in a patient with OSAHS. These agents have been reported to lead to sudden death, even in the preoperative holding area. These drugs suppress respiration, blunt the arousal response, and may lead to life-threatening hypoxemia. Benzodiazepine agonists affect upper airway muscle tone and worsen sleep apnea. Flurazepam has been shown to increase the Apnea Index, and triazolam increased the arousal threshold to airway obstruction, apnea and hypopnea duration, and oxygen desaturation. If a sleep apnea patient requires sedation or an anxiolytic, this necessitates continuous pulse oximetry and possibly supplemental oxygen.

2.5

Reflux/Aspiration Precautions

Obesity is common in patients with sleep-disordered breathing, leading to an increased risk of gastroesophageal reflux, which is caused by increased intraabdominal fat, increased intraabdominal pressure, and higher incidence of hiatal hernia. Ninety percent of obese patients have more than 25 mL of gastric fluid before surgery, have a pH under 2.5, and will be at increased risk of aspiration during induction of anesthesia or upon extubation. To reduce these risks, obese patients should receive an H ₂ blocker, proton pump inhibitor, or esophageal motility stimulant before surgery.

2.6

Medical/Anesthesia/Cardiology Clearance

A consultation with the primary physician, cardiologist, anesthesiologist, or other specialist should be considered in patients with complicated comorbid conditions or in patients with multiple comorbidities. For example, a patient with hypertension requiring three antihypertensive agents or a patient with poorly controlled diabetes may benefit from a preoperative clearance. The selection of an internist, cardiologist, or anesthesiologist may be based on availability or expertise of the consultant. The purpose of the preoperative clearance is to optimize control of the comorbidities before surgery and to reduce the risk of surgical complications.

Patients with OSAHS are at increased risk of hypertension due to an increased sympathetic drive. Undiagnosed hypertension is common in the sleep apnea patient. Blood pressure screening should be done at the time of initial evaluation or after initial diagnosis of OSAHS. If blood pressure is elevated, these patients should be referred for treatment. Blood pressure should again be checked at a preoperative visit to be sure that hypertension is well controlled.

2.7