To the Editor
Recent articles in the Anesthesia Patient Safety Foundation Newsletter strongly indicate that, at present, disastrous respiratory outcomes during the perioperative management of patients with obstructive sleep apnea (OSA) are a major problem for the anesthesia community.1,2 A recent review of the literature indicates that the disastrous outcomes are due to either intubation failure, respiratory obstruction soon after extubation, or respiratory arrest after narcotic and sedative medication (both preoperatively and postoperatively).3 In order to diminish the frequency and severity of these negative outcomes there are many problems that must be (urgently) solved. The most major and urgent problem areas are a failure to recognize the disease preoperatively, uncertainties regarding perioperative airway management, and the scheduling and management of OSA patients for outpatient surgery.
First, although general physician (primary care doctors, surgeons, anesthesiologists) recognition of OSA is rapidly growing,4,5 the preoperative management system must still deal with the fact that 80-95% of the approximately 18 million Americans believed to have OSA presently come to anesthesia and surgery without a diagnosis of OSA.6,7 Consequently, the anesthesiologist remains the last physician who has a chance to make a presumptive clinical diagnosis of OSA prior to surgery for most patients who actually have OSA. Nevertheless, even if the anesthesiologist does have a high degree of suspicion or does make a presumptive clinical diagnosis of OSA based on abnormal breathing during sleep (apnea and/or snoring), frequent arousals (periodic extremity twitching, vocalization, turning, snorting) and daytime somnolence, the degree of severity of the OSA, as quantified by a sleep study apnea hypopnea index (AHI), is still missing. Postoperative pain control and mechanical ventilation decisions are likely to be different for patients with an AHI of 14 vs. 64 (i.e., high mild vs. very severe). Furthermore, the prudent anesthesiologist will also want to know the cardiovascular ravages of OSA such as dual circulation hypertension, biventricular failure, the lowest SpO2 and presence of arrhythmias during sleep. Finally, since 60-90% of OSA patients are obese (BMI >29 kg/m2),3,8 preoperative baseline PaCO2 is necessary to diagnosis the presence of the Obesity Hypoventilation Syndrome (OHS). Postoperative pain control and mechanical ventilation decisions are also likely to be different for patients with a preoperative PaCO2 of 42 mmHg (no OHS) vs. 58 mmHg (definite OHS). Often none of the above information, essential for making intelligent, objective perioperative management decisions, is available preoperatively (especially in outpatient settings). We need an entire new preoperative management system to properly evaluate OSA patients.
Second, anesthesiologists need to prove or disprove the validity of current airway management techniques. We need to know when an awake intubation is required. The second iteration of the American Society of Anesthesiologists’ Difficult Airway Algorithm (approved by the House of Delegates 10/02) will contain an eleven-step difficult tracheal intubation evaluation scheme. Assuming that recognition of difficult intubation results in awake intubation as per the original American Society of Anesthesiologists’ Difficult Airway Algorithm,9-11 does strict adherence to the new scheme decrease/eliminate intubation failures? Is mask ventilation with the use of bilateral jaw thrust and mask seal (which requires a two-person effort) with an in situ oropharyngeal airway more efficacious than unilateral jaw thrust and mask seal (as is classically delivered by a single practitioner)? We need to know who requires an unquestionable awake extubation. Many other important questions remain to be answered. What is a really good endpoint for an awake extubation (i.e., how do we know the pharyngeal muscles have enough tone to hold the airway open spontaneously?), and how do we achieve that endpoint? Is that endpoint a rational oriented patient who responds to commands in a clear, crisp, and unambiguous manner, or is it something less definite than that? Is the risk:benefit analysis for extubation different for OSA patients awakening from postnasal surgery, or for OSA patients with severe coronary artery disease, or severe asthma, who may have an increased risk of nasal bleeding, myocardial infarction, and bronchospasm, respectively, if they were to undergo an awake extubation? Who should receive postoperative CPAP? If the patient was on nocturnal CPAP preoperatively, should the patient always be on CPAP postoperatively (including the time period before the patient goes into a deep natural sleep)? Finally, postoperative pain management represents a huge problem. We need to know who can/should go to an ICU, vs. a step-down unit, vs. an isolated room on a ward, vs. home. For those patients without continuous visual surveillance, will remote pager oximetry monitoring systems allow a caregiver to be more consistently in touch with the patient?
Lastly, and most importantly, managing the OSA patient in the outpatient setting is an enormous problem. It is absurd to think that we can manage a 5′ 8”, 440 lb, BMI = 69, morbidly obese patient with a history consistent with severe OSA for an outpatient knee arthroscopy in the same manner as we do for a non-OSA, normal weight patient. Nevertheless, this difficult problem is currently being presented to many anesthesiologists daily. Anesthesiologists in outpatient facilities are being presented with these difficult situations because the primary care doctors and surgeons do not recognize and work up the disease. There is a desperate need for all same day surgery/ambulatory/outpatient surgery facilities (meaning the anesthesiologist, surgeons, and nurses who work there) to write policies and procedures for acceptable outpatient surgery candidates that take into consideration the special problems and risks of OSA patients. Writing down the acceptable boundaries will necessarily increase medical awareness of the disease and help to decrease the administration of anesthetics to risky patients in risky environments.
The frequency and severity of adverse outcomes in OSA patients undergoing anesthesia and surgery will likely not decrease until these preoperative evaluation deficiencies, intraoperative airway, postoperative pain management, and outpatient scheduling problems are solved. It is hoped that this letter will at least cause the thoughtful reader, whether it be an anesthesiologist, surgeon, perioperative nurse, hospital administrator, or third party payer administrator, to try to help solve these problems.
Jonathan L. Benumof, MD
San Diego, California
- Lofsky A. Sleep apnea and narcotic postoperative pain medication: a morbidity and mortality risk. APSF Newsletter 2002;17:24-5.
- Benumof JL. Creation of observational unit may decrease sleep apnea risk. APSF Newsletter 2002;17:39.
- Benumof JL. Obstructive sleep apnea in the adult obese patient: implications for airway management. J Clin Anesth 2001;13:144-56.
- Collop NA. Conundrums in sleep medicine. Chest 1999;115:607-8.
- Pack AI, Gurubhagavatula I. Economic implications of diagnosis of obstructive sleep apnea. Ann Intern Med 1999;130:533-4.
- National Commission on Sleep Disorders Research: Wake up America: A National Sleep Alert. Washington D.C.: Government Printing Office, 1993.
- Young T, Evans L, Finn L, Palta M. Estimation of the clinically diagnosed proportion of sleep apnea syndrome in middle-aged men and women. Sleep 1997;20:705-6.
- Bresnitz EA, Goldberg R, Kosinski RM. Epidemiology of obstructive sleep apnea. Epidermiol Rev 1994;16:210-27.
- Practice guidelines for management of the difficult airway. A report by the American Society of Anesthesiologists Task Force on Management of the Difficult Airway. Anesthesiology 1993;78:597-602.
- Benumof JL. Management of the difficult airway: with special emphasis on awake tracheal intubation. Anesthesiology 1991;75:1087-110.
- Benumof JL. Laryngeal mask airway and the ASA difficult airway algorithm. Anesthesiology 1996;84:686-99.