EPIDURAL ANALGESIA WITH 4 MG OF MORPHINE FOLLOWING CESAREAN-SECTION - EFFECT OF INJECTED VOLUME

The efficacy and side effects of epidural bolus injection of 4 mg of morphine in a volume of 2 ml, 10 ml, or 20 ml (groups I, II and III) for postoperative analgesia after caesarean section (60 patients) were evaluated. All patients had epidural anaesthesia established up to T4 level with 0.5% bupivacaine 18-20 ml, supplemented with 2% lidocaine with adrenalin, when necessary. Morphine 4 mg in either of the three volumes was injected through the epidural catheter in random order after delivery of the baby. Six patients in each group reported no pain during the 24-h follow-up period. No additional pain medication during the 24 h after surgery was required in 11, 14 and 10 patients in groups I, II and III, respectively. Most of the others managed with the addition of a single dose of rectal ketoprofen. There were no differences in analgesic therapy between the groups. Pruritus was the most common adverse effect (18/20, 19/20 and 18/20 in groups I, II and III, respectively). 10/20, 12/20 and 14/20 (N.S.) patients had nausea and vomiting in groups 1, II and III, respectively. Metoclopramide, prescribed for persistent nausea, was given to 4/20 patients in group I, 6/20 patients in group II and 9/20 patients in group III (N.S.). After removal of the urinary catheter 7/20.patient in group III required carbachol for urinary retention compared to 3/20 and 4/20 patients in groups I and Il (N.S.). In this study a tenfold dilution of 4 mg of morphine did not influence the quality of analgesia after caesarean section or cause statistically significant differences in the appearance of side-effects.