Epidural and intravenous bolus morphine for postoperative analgesia in infants

Purpose: To compare two doses of bolus epidural morphine with bobs iv morphine for postoperative pain after abdominal or genitourinary surgery in infants. Methods: Eighteen infants were randomly assigned to bolus epidural morphine (0.025 mg . kg(-1) or 0.050 mg . kg(-1)) or bolus iv morphine (0.050-0.150 mg . kg(-1)). Postoperative pain was assessed and analgesia provided, using a modified infant pain scale. Monitoring included continuous EGG, pulse oximetry, impedance and nasal thermistor pneumography. The CO2 response curves and serum morphine concentrations were measured postoperatively. Results: Postoperative analgesia was provided within five minutes by all treatment methods. Epidural groups required fewer morphine doses (3.8 +/- 0.8 for low dose [LE], 3.5 +/- 0.8 for high dose epidural [HE] vs. 67 +/- 1.6 for iv, P < 0.05) and less total morphine (0.11 +/- 0.04 mg . kg(-1) for LE, 0.16 +/- 0.04 for HE vs 0.67 +/- 0.34 for iv, P < 0.05) on POD1. Dose changes were necessary in all groups for satisfactory pain scores. Pruritus, apnoea, and haemoglobin desaturation occurred in all groups. CO2 response curve slopes, similar preoperatively (range 36-41 ml . min(-1). mmHg ETCO(2)(-1). kg(-1)) were generally depressed (range, 16-27 ml . min(-1). mmHg ETCO(2)(-1)kg(-1)) on POD1. Serum morphine concentrations, negligible in LE (<2 ng . ml(-1)), were similar in the NE and iv groups (peak 8.5 +/- 12.5 and 8.6 +/- 2.4 ng . ml(-1), respectively). Conclusion: Epidural and iv morphine provide infants effective postoperative analgesia, although side effects are common. epidural morphine gives satisfactory analgesia with fewer doses (less total morphine); epidural morphine 0.025 mg kg(-1) is appropriate initially. infants receiving epidural or iv morphine analgesia postoperatively need close observation in hospital with continuous pulse oximetry.