Obstructive sleep apnea (OSA) is a common form of sleep disordered breathing characterized by partial or complete upper airway obstructions during sleep. OSA is associated with major comorbidities and perioperative complications. These complications are caused not only by the OSA itself, but also by exacerbations of this syndrome during the perioperative period (1). Benzodiazepines, volatile anesthetics and opioids may lead to lower hypoxia and hypercapnia sensitivity and may cause respiratory depression (2-5). Therefore, preference of neuraxial blockades and avoidance of opioids has been suggested for patients with OSA (6). However, there is still lack of evidence to evaluate the effects of various anesthesia procedures on OSA (6,7). We hypothesize different anesthetic procedures will have different effect on OSA exacerbations in the postoperative period. Accordingly, the aim of this study is to compare the number of sleep disordered breathing episodes in the postoperative period in patients with different anesthetic procedures.

Inclusion Criteria:

• elective orthopedic surgery

Exclusion Criteria:

• already diagnosed sleep disorder breathing
• continuous positive airway pressure therapy
• tracheostomy
• American Society of Anesthesiologists class IV-V

consecutive patients undergoing elective orthopedic surgery