Postoperative complications in patients with obstructive sleep apnea syndrome undergoing hip or knee replacement: A case-control study

Objective: To identify and assess the impact of postoperative complications in patients with unrecognized or known obstructive sleep apnea syndrome (O SAS) undergoing hip replacement or knee replacement compared with control p atients undergoing similar operations. Although OSAS is a risk factor for p erioperative morbidity,, data quantifying the magnitude of the problem in p atients undergoing non-upper airway operations are limited. Patients and Methods: This retrospective, case-control study from a single academic medical institution included patients diagnosed as having OSAS bet ween January 1995 and December 1998 and undergoing hip or knee replacement within 3 years before or anytime after their OSAS diagnosis. Patients with OSAS were subcategorized as having the diagnosis either before or after the surgery and also, regardless of time of diagnosis, by whether they were us ing continuous positive airway pressure (CPAP) prior to hospitalization. Ma tched controls were patients without OSAS undergoing the same operation. In terventions were defined specifically as administration of a particular tre atment in the context of each complication, eg, supplemental oxygen, implem entation of additional monitoring such as oximetry for hypoxemia, or transf er to the intensive care unit (ICU) for cardiac ischemia concerns. Postoper ative complications were assessed for all patients in the different categor ies and included respiratory events such as hypoxemia, acute hypercapnia, a nd episodes of delirium. Serious complications were noted separately, inclu ding unplanned ICU days, reintubations, and cardiac events. The length of h ospital stay was also tabulated. Results: There were 101 patients with the diagnosis of OSAS in this study a nd 101 matched controls. Thirty-six patients had their joint replacement be fore OSAS was diagnosed, and 65 had surgery after OSAS was diagnosed. Of th e latter 65 patients, only 33 were using CPAP at home preoperatively. Compl ications were noted in 39 patients (39%) in the OSAS group and 18 patients (18%) in the control group (P=.001). Serious complications occurred in 24 p atients (24%) in the OSAS group compared with 9 patients (9%) in the contro l group (P=.004). Hospital stay was significantly longer for the OSAS patie nts at a mean SD of 6.8 +/-2.8 days compared with 5.1 +/-4.1 days for the c ontrol patients (P < .007). Conclusion: Adverse postoperative outcomes occurred at a higher rate in pat ients with a diagnosis of OSAS undergoing hip or knee replacement compared with a group of matched control patients.