Key Point

Risk of postoperative complications may be higher among patients with obstructive sleep apnea than among those without the condition.

BALTIMORE—Surgical patients with obstructive sleep apnea (OSA) have more postoperative complications than do those without OSA, according to research presented at the 22nd Annual Meeting of the Associated Professional Sleep Societies.

The final analysis included data for 211 patients who completed overnight polysomnography (PSG) prior to elective surgery at two Toronto hospitals. Study participants were limited to those 18 and older who had not received a prior OSA diagnosis, according to lead researcher Frances F. Chung, MD, Professor of Anesthesiology at the University of Toronto.

OSA was defined as an apnea-hypopnea index (AHI) of 5 or greater. For ethical reasons, if the PSG revealed a patient had an AHI greater than 30, the patient’s anesthesiologist was notified and medication was adjusted. “OSA patients are highly vulnerable to medications that suppress the pharynx and more sensitive to general anesthesia,” noted Dr. Chung.

PSG revealed 147 patients with an AHI of 5 or greater (the OSA group). At 27%, the proportion of postoperative complications was higher among patients with OSA than among patients in the non-OSA group, where 12% had complications postsurgery. The most common complication types were respiratory in nature (23% for the OSA group and 9% for the non-OSA group); 93% of patients with respiratory complications experienced desaturation, said Dr. Chung.

Fourteen percent of OSA patients received oxygen treatment postoperatively. Twelve OSA patients were transferred to the ICU following surgery, compared with one non-OSA patient. Dr. Chung reported statistically negligible differences in cardiac (7% vs 3%) and neurologic (1% vs 0%) complications between the OSA and non-OSA groups, respectively.

Patients with OSA tended to be older than patients in the non-OSA group (59 vs 50, respectively), more obese (BMI of 30.6 vs 28.6), male (57% vs 36% were men) and to have a higher prevalence of hypertension (49% vs 31%). While patients in neither group faced life-threatening complications, Dr. Chung said that anecdotal reports have tied postoperative fatalities to complications attributed to OSA.

Of the 2,000 patients who were screened for the study, 416 had originally consented to participate. Of those, 49% were “no shows” for the overnight PSG study, Dr. Chung explained. Ultimately, the high rate of refusal to participate may have created a self- selection bias, she acknowledged. Dr. Chung attributed unwillingness to participate to anxiety about the coming surgery and the inconvenience of spending a night in the sleep laboratory. Smokers and younger patients were the most likely not to show up for their scheduled PSG, she added.

—Kathlyn Stone

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