A1248
October 21, 2008
8:00 AM - 11:00 AM
Room W414AB

Postoperative Complications in Patients with Obstructive Sleep Apnea, a Case-Control Study
Frances Chung, F.R.C.P.C., Pu Liao, M.D., Balaji Yegneswaran, M.B.B.S., Santhira Vairavanthan, M.B.B.S.
Department of Anesthesia, Toronto Western Hospital, University Health Network, Toronto, Ontario, Canada

Introduction:
Obstructive Sleep Apnea (OSA) is presumed to be a risk factor for perioperative morbidity and mortality. At present the data quantifying the magnitude of perioperative complications due to OSA is very limited to make any major correlations. This retrospective case control study is to determine the occurrence of perioperative respiratory complications among the surgical patients with OSA.

Methods:
Hospital ethics approval was obtained. All patients diagnosed with OSA and age >18 years, who underwent surgeries other than uvulopalatopharyngoplasty in two teaching hospitals for 10 years were selected. A total of 275 charts were studied and subjected to 1:1 match with controls. The match criteria include the same gender, same type of surgery, age difference less than 5 years and the difference of surgery date less than 5 years. Of 275, 240 charts had been matched with the appropriate controls. The analysis was based on the data from 240 pairs matched cases and controls. The data collected through chart review were entered into a specifically designed MS Access database and analyzed with SAS 9.1 for Windows.

Result:
In 240 pairs of matched case and control, 184 pairs (77%) were male and 56 pairs (23%) female; age was 57±13 years for both OSA and control group. Compared with control group, the OSA group had bigger BMI (35±9 vs 28±6, p<0.05), higher frequency of pre-existing medical conditions, such as hypertension (48% vs 36%, p<0.05), obesity (61 % vs 23 %, p<0.05), hythyroidism (19 % vs 5%, p<0.05), GERD (27 % vs 17%, p<0.05), Asthma (19% vs 8%, p<0.05) and COPD (9 % vs 4% , p <0.05). The incidence of total postoperative complication in OSA group was significantly higher than control group (44% vs 28%, p<0.05). There was no difference between two groups in terms of the occurrence of cardiac and neurological complications. The increased incidence of respiratory complication (33% vs 22%, p<0.05) was the major cause for significantly higher postoperative complications in OSA group. Severe desaturation was the most common complication (17% vs 8%, p<0.05). As a result, there was a need for extra treatments in OSA group, such as prolong oxygen therapy and additional monitoring. When checking the effect of different factors on the occurrence of postoperative complications individually; diagnosed as OSA, ASA status ranked as III or IV, pre-existing hypothyroidism and asthma were the significant risk factors. The odds ratio of OSA for occurence postoperative complication was 2.0 (95% CI: 1.4- 2.9 ).

Conclusion:
Compared to the matched controls, the surgical patients with OSA had a significantly higher incidence of postoperative complications, mainly due to significantly increased respiratory complications and extra treatment was often required.

Anesthesiology 2008; 109 A1248