Does Autotitrating Positive Airway Pressure Therapy Improve Postoperative Outcome in Patients at Risk for Obstructive Sleep Apnea Syndrome? A Randomized Controlled Trial

Study Questions:

Does autotitrating positive airway pressure therapy improve postoperative outcome in patients at risk for obstructive sleep apnea (OSA) syndrome?


Subjects were enrolled from a single-center orthopedic clinic between 2002 and 2005. Patients with known OSA or prior use or recommended positive airway pressure (PAP) therapy were excluded. For safety reasons, patients with high risk for OSA and >10% cardiovascular risk for cardiac complications were advised to undergo overnight oximetry. If oximetry results were abnormal, patients were excluded. Patients were divided into low and high risk of OSA based on validated questionnaire. Those classified as high risk for OSA were randomized to standard care or standard care plus autotitrating PAP (APAP). Patients at low risk received standard care. All patients were administered a predischarge cardiorespiratory sleep study. The primary endpoint was length of stay, and secondary endpoints were a range of postoperative complications.


To study 138 patients, 2,375 were screened for eligibility. Refusal to participate (n = 1,964) and ineligible (n = 273) were reasons for exclusion. On the basis of the screening questionnaire, 52 and 86 patients were found to be low and high risk, respectively. Within the high-risk group, 43 were randomized to standard postoperative care and 43 to standard postoperative care plus postoperative APAP. Patients tended to be obese (mean body mass index [BMI], 33.9 kg/m2), elderly (median age, 65.5 years), and men (68.8%). The high-risk group had a greater proportion of males and a higher BMI (p < 0.0001 for both comparisons). The high-risk group also had a higher prevalence of comorbidities. After randomization within the high-risk group, male patients were more prevalent in the standard care group (p = 0.03), but other characteristics were similar. There were no significant differences in the length of stay (p = 0.65) or any of the secondary endpoints between the randomized groups. On subgroup analysis, of patients with an apnea-hypopnea index of ≥15, patients randomized to APAP had a longer postoperative stay (median, 5 vs. 4 days; p = 0.02).


The authors concluded that there was no benefit for APAP applied postoperatively to PAP-naïve patients at high risk for sleep apnea.


Clinical judgment would support a treating physician’s decision to empirically implement PAP in a postoperative setting in patients at high risk for OSA, who do not use PAP preoperatively. In the present study, in 38 randomized patients who used APAP, only 14 had effective control of sleep-disordered breathing. This low effective use rate, combined with a low overall complication rate, may help explain some of the findings. Perhaps APAP exerts a negative outcome related to other aspects of postoperative care, such as recovery of bowel function. Use of postoperative APAP therapy requires further study. At present, APAP cannot be recommended for use in PAP-naïve patients.

Clinical Topics: Heart Failure and Cardiomyopathies, Sleep Apnea

Keywords: Oximetry, Postoperative Care, Questionnaires, Sleep Apnea Syndromes

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