Patients with undiagnosed obstructive sleep apnea (OSA) are thought to be at higher risk after an operation than those who have already been diagnosed and are being treated with CPAP therapy. Current practice guidelines recommend screening for obstructive sleep apnea before an operation, and starting CPAP therapy prior to surgery if feasible. Routine monitoring of patients with OSA is recommended after many types of surgery.
This study looked at historical outcomes after surgery that occurred before the implementation of the current practice guidelines. The study included data on adults and compared them to controls at low risk of having sleep apnea. The control patients were matched for the type of surgery, indication for the surgery, and date of the surgery.
The results showed that the risk of cardiovascular complications, primarily cardiac arrest and shock, was increased in undiagnosed obstructive sleep apnea but not diagnosed obstructive sleep apnea. However the risk of respiratory complications, primarily Acute Respiratory Distress Syndrome (ARDS) and acute respiratory failure was increased in both groups without significant difference in risk between them. Also, the results showed that increasing severity of obstructive sleep apnea, age, comorbid disease, and the type of surgery were also important risk predictors for postoperative complications.
The study was not designed to determine whether reduction in cardiovascular complications in those patients diagnosed with OSA was due to CPAP use as usage of CPAP was not measured immediately after surgery.