A1246
October 21, 2008
8:00 AM - 11:00 AM
Room W414AB

Postoperative Events in Patients at Risk for Obstructive Sleep Apnea Undergoing Elective Surgery
Bhargavi Gali, M.D., Francis X. Whalen, M.D., Darrell R. Schroeder, M.S., Peter C. Gay, M.D., David J. Plevak, M.D.
Anesthesiology, Mayo Clinic, Rochester, MN

Background:
Patients with obstructive sleep apnea (OSA) are at risk for perioperative morbidity. Although guidelines have been promulgated,¹ the risk and management of patients with suspected OSA is unknown.. The purpose of this study was to determine if a screening test for OSA² could predict postoperative and cardiac respiratory events occurring after postanesthesia care unit (PACU) discharge. We also determined whether observed respiratory parameters while in the PACU would further predict which patients were at risk for events after PACU discharge.

Methods: This prospective cohort study was approved by the Institutional Review Board. Patients presenting to the preoperative evaluation clinic (without previous diagnosis of OSA) undergoing inpatient surgery with a greater than 48 hour expected hospital stay were enrolled. The sleep apnea clinical score (SACS) was used to determine whether patients were at high (SACS≥15) or
low risk for OSA. SACS utilizes hypertension, neck circumference, and historical factors (snoring, gasping, choking) to generate a linear regression module. Patients were monitored for recurrent episodes of bradypnea (RR<8/min), apnea (>10 seconds), desaturations (<90% repeatedly), and pain-sedation mismatch (high pain score associated with high sedation score) at 3 time points 30 minutes apart. All patients underwent 48 hours (or until hospital discharge) monitoring with continuous pulse oximetry postoperatively to calculate the oxygen-desaturation index (ODI= number of desaturations/hour of >4% for ≥10 seconds). Prospectively determined respiratory and cardiac events were noted. Chi-square, two-sample t-test, and logistic regression were utilized. Results: In 693 patients, we found that both a high SACS score and the occurrence of recurrent respiratory events in the PACU were significant independent risk factors for both ODI>10 and postoperative respiratory complications after PACU discharge. In patients who did not experience recurrent PACU events, a high SACS still was associated with a higher frequency of an ODI > 10, but not non-respiratory complications.

Discussion: Utilization of both preoperative screening (SACS) and the observation of recurrent PACU respiratory events predicted a higher ODI and postoperative respiratory complications after PACU discharge. A two phase process to identify patients at higher risk for perioperative respiratory desaturations and complications may be useful to manage surgical patients postoperatively.

References:
1. Anesthesiology 2006;104:1081-93.
2. Am J Resp Crit Care Med 1994;150:1279-85.
Anesthesiology 2008; 109 A1246