PURPOSE: Obstructive Sleep Apnea (OSA) is thought to increase postoperative morbidity and mortality, however the efficacy of post-operative intervention with non-invasive positive airway pressure is unproven. The aim of our study was to evaluate the effect on post-operative outcome of treating orthopedic patients, identified as high-risk for OSA, with post-operative auto-titrating positive airway pressure (APAP). Length of stay and occurrence of post-operative complications were examined. We also aimed to assess the accuracy of the OSA risk assessment in an orthopaedic population.
METHODS: Patients, scheduled for total hip or knee replacement, were prospectively assessed for risk of OSA using a clinical prediction tool. Patients assigned low risk status received standard post-operative care. The high-risk group was randomized to receive standard post-operative care alone or in addition to post-operative APAP therapy. All patients underwent a cardio-respiratory sleep study post-operatively to determine the presence of OSA.
RESULTS: In this study 137 patients were enrolled between 2002 and 2005. 52 were assigned low-risk and 85 high-risk status. Within the high-risk group 42 were randomized to standard care and 43 to receive additional post-operative APAP. Patients allocated high-risk status were more likely to have a post-operative complication than those of low-risk status, greater than 23% compared to less than 2%(p-value 0.0008). Length of stay did not vary between the two groups. Within the high-risk group, application of post-operative APAP did not affect length of stay or rate of post-operative complications. The presence of OSA, as determined by the cardio-respiratory sleep study, did not predict length of stay or rate of post-operative complications.
CONCLUSIONS: In this study high-risk status for OSA, as determined by a simple four-point questionnaire, identified patients at increased risk for post-operative complications. Application of post-operative APAP in the high-risk group did not alter post-operative outcome.
CLINICAL IMPLICATIONS: Further study is warranted to determine the clinical role for the OSA questionnaire in predicting those patients at increased risk of post-operative complications, who may benefit from heightened post-operative monitoring.
DISCLOSURE: Peter Gay: Grant monies (from industry related sources): Dr. Gay has a grant from ResMed to study patients with complicated sleep-disordered breathing
Timothy Morgenthaler: Grant monies (from industry related sources): Dr. Morgenthaler has a research grant from ResMed to study therapy of patients with Complex Sleep Apnea Syndrome.
The following authors have nothing to disclose: Susan O'Gorman, Terese Horlocker, Jeanne Huddleston
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