Postoperative hypoxemia in orthopedic patients with obstructive sleep apnea

Criteria to determine which patients with obstructive sleep apnea (OSA) require intensive postoperative monitoring are lacking. Our postoperative OSA patients are all intensively monitored in the PACU and can provide such data. Thus, we reviewed patient records to determine incidence and risk factors for postoperative hypoxemia in OSA patients and subsequent association with postoperative complications. Five hundred twenty-seven charts of patients with OSA based on preoperative ICD-9 codes were reviewed for outcomes including episodes of hypoxemia and hypercarbia. Univariate analysis, logistic regression, and propensity analysis were performed to determine independent risk factors for hypoxemia and association with adverse outcomes. Thirty-three and 11 percent of these patients developed hypoxemia or hypercarbia. Risk factors for hypoxemia were hypercarbia, home bronchodilator use, BMI ≥35, and estimated blood loss ≥250 ml. Patients with hypoxemia had significantly more respiratory interventions and increased intensity of care. Patients with hypoxemia had significantly increased length of stay and risk of wound infections. Severe hypoxemia was associated with significantly more interventions than mild hypoxemia. Propensity analysis confirmed significant association of hypoxemia with adverse outcomes after adjustment for pre-existing risk factors. We conclude that postoperative hypoxemia in OSA patients is associated with adverse outcomes. Risk factors for hypoxemia were identified to guide allocation of monitoring resources to high-risk patients.