Effect of mini-dose dexmedetomidine supplemented intravenous analgesia on sleep structure in older patients after major noncardiac surgery: A randomized trial.

STUDY OBJECTIVES: In previous studies, low-dose dexmedetomidine supplemented opioid analgesia improved sleep architecture but increased sedation level. Herein we tested the hypothesis that mini-dose dexmedetomidine supplemented analgesia improves sleep structure without increasing sedation. METHODS: In this randomized trial, 118 older patients (≥65 years) following major noncardiac surgery were randomized to receive patient-controlled intravenous analgesia supplemented with either placebo or dexmedetomidine (median 0.02 µg kg-1 h-1) for up to 3 days. Polysomnogram was monitored from 9:00 p.m. on the day of surgery until 6:00 a.m. on the first day after surgery. Our primary outcome was the percentage of non-rapid eye movement stage 2 (N2) sleep. Secondary outcomes included other sleep structure parameters during the night of surgery and the sedation score during the first five postoperative days. RESULTS: All 118 patients completed the study; of these, 85 were included in sleep structure analysis. Dexmedetomidine supplemented analgesia increased the percentage of N2 sleep (median difference, 10%; 95% CI, 1%-20%; P = 0.03). It also prolonged total sleep time (median difference, 78 min; 95% CI, 21 to 143; P = 0.01), increased sleep efficiency (median difference, 14%; 95% CI, 4%-26%; P = 0.01), decreased percentage of N1 sleep (median difference, -10%; 95% CI, -20% to -1%; P = 0.04), and lowered sleep fragmentation index (median difference, -1.6 times⋅h-1; 95% CI, -3.7 to 0.1; P = 0.04). Sedation score within 5 days did not differ between the two groups. CONCLUSIONS: Supplementing intravenous analgesia with mini-dose dexmedetomidine improved sleep structure without increasing sedation in older patients recovering from major surgery. CLINICAL TRIALS: www. CLINICALTRIALS: gov (NCT03117790), registered 2 April 2017.