Preliminary results of prolonged target controlled infusion of sufentanil adjusted to an effort pain score after cardiac surgery.

Repeated boluses of i.v. morphine are often used for analgesia after cardiac surgery, but this procedure frequently provides inadequate pain relief. Target controlled infusion (TCI) of opioid drugs has been proposed as an alternative. The objective of this study was to evaluate the effects of prolonged sufentanil TCI adjusted to an effort pain score on the postoperative course after cardiac surgery. Twenty-six patients scheduled for cardiac surgery were anaesthetised using TCI of propofol and sufentanil, followed by early extubation. In the postoperative period, patients were randomly allocated to receive either boluses of i.v. morphine (Bolus group), adapted to a pain score at rest, or sufentanil TCI with a low target concentration (0.08-0.1 ng/ml), adapted to a pain score during deep inspiration (TCI group). Postoperative pain was assessed using a Verbal Numerical Score (VNS) before and during three stimuli: extubation, lateral positioning and physiotherapy. In 15 patients, inspiratory capacity was evaluated by incentive spirometry (IS) on postoperative day 1. Three patients in each group were withdrawn because of delayed extubation. Clinical characteristics, mean time to extubation and PaCO2 were similar in both groups. Analgesia was adequate at rest in both groups as indicated by low pain scores. Pain intensity increased significantly during the three stimuli (p < 0.01). VNS were lower in the TCI than in the Bolus group (3.8 +/- 0.5 versus 4.8 +/- 0.5, p = 0.03). Nine of 10 patients in the TCI group but only 4 of 10 patients in the bolus group gave a VNS below 5 during the stimuli. IS performance was better preserved in the TCI than in the Bolus group (53 +/- 5% versus 35 +/- 5% of preoperative values, p < 0.05). These observations indicate that after cardiac surgery, postoperative pain management with prolonged TCI of sufentanil adapted to a pain score during deep inspiration can achieve better analgesia during routine bedside procedures and higher pulmonary volumes than on-demand boluses of morphine.