Intravenous morphine and droperidol after caesarean delivery under subarachnoid anaesthesia has no effect on postoperative pain or analgesic requirements

Abstract

Background and objective: Opioids are routinely administered to obtain a better control of postoperative pain. The aim of the present study was to assess the intravenous morphine effect after caesarean delivery on the postoperative morphine requirements and pain.

Methods: Sixty-two parturients undergoing elective caesarean section under subarachnoid anaesthesia were randomly assigned in a double-blinded manner to the morphine or to the control group, to receive intraoperatively 0.15 mg kg morphine in 100 ml of isotonic saline or equal volume of normal saline. Postoperative analgesia was ensured with patient-controlled analgesia morphine. Postoperative pain at rest and after cough was assessed using the visual analogue scale (VAS) 2, 4, 8, and 24 h. Morphine consumption was recorded at the same time points.

Results: Cumulative morphine consumption 2, 4, 8, and 24 h postoperatively was 6 +/- 4.8, 14 +/- 6.6, 22 +/- 9.6, and 42 +/- 15.7 mg in the morphine and 8 +/- 5.1, 18 +/- 7.7, 28 +/- 9.4, and 43 +/- 17.4 mg in the control group (F = 2.70, DF = 1, and P = 0.105 for intergroup comparisons). The VAS scores at rest did not differ between the two groups, being 28 +/- 22.3, 40 +/- 21.4, 28 +/- 18.5, and 28 +/- 22.2 mm in the morphine group and 28 +/- 21.5, 43 +/- 23.5, 29 +/- 24.2, and 19 +/- 24.8 mm in the controls (F = 0.37, DF = 1, P = 0.848). Similar results apply to the VAS scores recorded after cough. VAS values were 35 +/- 20.6, 51 +/- 22.5, 42 +/- 18.2, and 46 +/- 23.6 mm in the morphine and 40 +/- 22.1, 54 +/- 28.9, 47 +/- 26.5, and 38 +/- 26.9 mm in the control group, respectively.

Conclusion: Morphine given after caesarean delivery under subarachnoid anaesthesia has no effect on analgesic requirements or acute postoperative pain.