Dextromethorphan and intrathecal morphine for analgesia after Caesarean section under spinal anaesthesia.
BACKGROUND
Dextromethorphan is an N-methyl-D-aspartic acid antagonist which can attenuate acute pain with few side-effects. In this prospective, randomized, double-blind study of dextromethorphan and intrathecal morphine, we investigated postoperative pain, pruritus, nausea and vomiting in women undergoing Caesarean section under spinal anaesthesia.


METHODS
Women were allocated randomly to one of six groups, to receive intrathecal morphine 0.05, 0.1 or 0.2 mg plus oral dextromethorphan 60 mg or placebo.


RESULTS
The addition of dextromethorphan did not reduce postoperative pain scores (P=0.83). Compared with women receiving intrathecal morphine 0.05 mg, women receiving higher doses had a significantly higher incidence of nausea and vomiting [odds ratio for intrathecal morphine 0.1 mg, 4.0 (95% confidence interval 1.2-14.1); for intrathecal morphine 0.2 mg, 7.9 (2.3-27.1)]. Compared with women receiving intrathecal morphine 0.05 mg, women receiving higher doses also had a significantly higher incidence of pruritus [odds ratio for intrathecal morphine 0.1 mg, 3.2 (95% confidence interval 1.3-8.2); for intrathecal morphine 0.2 mg, 3.7 (1.4-9.5)]. Women receiving dextromethorphan had a lower incidence of nausea and vomiting [odds ratio 2.6 (1.1-6.3)].


CONCLUSIONS
Postoperative pain after Caesarean section under spinal anaesthesia was not reduced by the addition of oral dextromethorphan to a multimodal approach including intrathecal morphine.
Choi
D M A
DM
Department of Anesthesia, British Columbia Women's Hospital, Vancouver, Canada. Desi.Choi@orh.nhs.uk
Kliffer
A P
AP
Douglas
M J
MJ
D000328:Adult; D016362:Analgesia, Obstetrical / Q000379:methods*; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects; D000773:Anesthesia, Obstetrical / Q000379:methods; D000775:Anesthesia, Spinal; D002585:Cesarean Section; D003915:Dextromethorphan / Q000008:administration & dosage*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004359:Drug Therapy, Combination; D018691:Excitatory Amino Acid Antagonists / Q000627:therapeutic use; D005260:Female; D006801:Humans; D009020:Morphine / Q000008:administration & dosage / Q000009:adverse effects; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000517:prevention & control*; D020250:Postoperative Nausea and Vomiting / Q000139:chemically induced / Q000517:prevention & control; D011247:Pregnancy; D011446:Prospective Studies; D011537:Pruritus / Q000139:chemically induced; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors
D000701:Analgesics, Opioid; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D003915:Dextromethorphan; D009020:Morphine