Mechanisms of postoperative sleep architecture disturbances and sleep-disordered breathing are uncertain. The authors hypothesised that patients undergoing surgery under regional anaesthesia without opioids used for postoperative analgesia would experience lesser changes in these parameters than patients operated under general anaesthesia with per- and postoperative opioids.

After ethical approval and informed consent, patients undergoing total hip replacement were included in a prospective, randomised trial comparing 3 groups of patients: (1) S-LPB group receiving spinal anaesthesia and postoperative analgesia by lumbar plexus block; (2) GA-PCA group receiving general anaesthesia and postoperative analgesia by morphine patient-controlled analgesia; (3) GA-LPB group receiving general anaesthesia and postoperative analgesia by lumbar plexus block. Outcome measurements were polysomnographic parameters of sleep architecture and sleep-disordered breathing.

Eighteen patients completed the 5-night study protocol (preoperative night: N-1, postoperative nights: N1 to N4). The percentage of rapid eye movement (REM) sleep decreased by 49% and 47% during N1 in the GA-PCA and GA-LPB groups respectively. A rebound phenomenon of more than 40% in the GA-PCA group and 25% in the GA-LPB group was observed during N2 and N3. Apnoea hypopnoea index (AHI) and the number of arousals per hour were significantly increased during N2 and N3 when compared with N-1 in the GA-groups. No sleep architecture disturbances and no sleep-disordered breathing were measured in the S-LPB group.

Postoperative sleep architecture and breathing pattern were disturbed in GA groups. Both were preserved under spinal anaesthesia associated with a free opioid postoperative analgesia.