Background:

Anesthesia and surgery both affect the architecture of sleep. Aside from the postoperative effects of anesthesia and surgery, sleep deprivation and fragmentation have been shown to produce apneas or desaturations even in patients without presumed sleep apnea. Adverse surgical outcomes appear to be more frequent in Obstructive Sleep Apnea Syndrome (OSAS) patients. Immediate postoperative complications may intuitively be attributed to negative effects of sedative, analgesic and anesthetic agents which can worsen OSAS by decreasing pharyngeal tone and arousal responses to hypoxia, hypercarbia and obstruction. Later events are however more likely related to postoperative Rapid Eye Movement Sleep (REM) rebound. In the severe OSAS patient, REM rebound could conceivably act in conjunction with opiod administration and supine posture to aggravate sleep disordered breathing. REM rebound has also been suggested to contribute to mental confusion and postoperative delirium, myocardial ischemia/infarct, stroke and wound breakdown.

Method:

We looked retrospectively at 25,587 patients who underwent cardiac surgery at a major tertiary care center. 37 of these patients were known to have OSA by Polysomnography. An assumption was made that if the surgery was performed within two years of the diagnosis of OSA, the patient had OSA at the time of the surgery.

Summary of Results:

Higher incidence of perioperative complications were observed in this group of patients. These included encephalopathy, postoperative infection and increased ICU length of stay.

Statement of Conclusions:

Obstructive Sleep Apnea (OSA) is not generally acknowledged as a perioperative risk factor. Recent epidemiologic data have placed the prevalence of Obstructive Sleep Apnea Syndrome (OSAS) at about 5% among the Western countries. Even higher incidence of Sleep disordered breathing has been noticed in patients with cardiovascular disease. The problem is further hindered by the difficulty in diagnosing OSAS. As such patients with sleep apnea may present for surgery without a prior diagnosis and sleep apnea may first be recognised intraoperatively. Adverse surgical outcomes appear to be more frequent in OSAS patients.

Author Disclosure Block:

R.K. Kaw, None.