Opioid-induced sedation in the postanesthesia care unit does not insure adequate pain relief: A case-control study

BACKGROUND: Sedation can occur during intravenous titration of morphine for acute pain control in the postanesthesia care unit (PACU). We designed this case-control study to evaluate the relationship between opioid-induced sedation in the PACU and adequacy of early postoperative analgesia. METHODS: Intravenous morphine was titrated in 2 mg (body weight ! 60 kg) or 3 mg (body weight > 60 kg) boluses every 5 min to treat moderate-to-severe pain in the PACU. Pain was assessed using a 11-point verbal rating scale (VRS) with scores >= 3 representing moderate-to-severe pain. The 6-point Ramsay score was used to assess the level of sedation with scores > 3 representing clinically significant sedation. Twenty-six patients, with a Ramsay sedation score > 3 and a pain VRS >= 3 at discharge from the PACU, were evaluated 24 h after surgery to assess (a) the recall of early postoperative pain in the PACU, (b) quality of sleep on the first night after surgery, (c) pain on the 24th postoperative hour, and (d) satisfaction with pain management at 24 h after surgery. Two patients discharged from the PACU with VRS pain scores < 3 were matched to each of the patients with pain scores >= 3 and Ramsay score > 3, as part of a 52 patient control group. RESULTS: Patients with Ramsay scores > 3 and pain scores >= 3 more frequently reported moderate-to-severe pain in the PACU (severe/moderate/no pain: 18%/25%/57% vs 58%/16%/26%, P = 0006, for the control and the sedated group, respectively), poorer quality of sleep the night after surgery (well/moderate/bad: 48%/42%/10% vs 23%/23%/54%, P = 0.001, for the control and the sedated group, respectively), and higher pain scores at the 24th hour after surgery (severe/moderate/no pain: 6%/44%/50% vs 50%/42%/8%, P < 0.0001, for the control and the sedated group, respectively). In addition, their overall satisfaction with pain control during the first 24 postoperative hours was lower (satisfied/moderately satisfied/not satisfied: 96%/2%/2% vs 50%/30%/20%, P < 0.0001, for the control and the sedated group, respectively). CONCLUSION: Clinically significant opioid-induced sedation in the PACU does not insure adequate self-reported pain relief.