Efficacy of mirtazapine in preventing intrathecal morphine-induced nausea and vomiting after orthopaedic surgery*.

Nausea and vomiting are frequent complications of intrathecal morphine. In this randomised, double-blind trial, we tested the efficacy of mirtazapine, an antidepressant that blocks receptors associated with vomiting, on the incidence of nausea and vomiting after intrathecal morphine. One hundred patients receiving spinal anaesthesia for lower limb surgery were assigned equally to take either an orally disintegrating form of 30 mg mirtazapine or matching placebo 1 h before surgery. Spinal anaesthesia was performed by injection of 15 mg isobaric bupivacaine 0.5% along with 0.2 mg preservative-free morphine. Nausea and vomiting were evaluated 3, 6, 12, 18 and 24 h after intrathecal morphine administration. The incidence of nausea and vomiting was significantly lower in patients receiving mirtazapine compared with placebo (26.5% vs 56.3%, respectively; p = 0.005). The mean (SD) onset time of postoperative nausea and vomiting was significantly delayed in mirtazapine patients: 9.4 (2.5) vs 5.2 (1.8) h, respectively; p < 0.0001. The severity of nausea and vomiting was also decreased after mirtazapine at the 3-6 h and 6-12 h periods. Our data indicate that pre-operative mirtazapine decreases the incidence, delays the onset and reduces the severity of nausea and vomiting induced by intrathecal morphine in patients undergoing spinal anaesthesia.

Prophylactic mirtazapine reduces intrathecal morphine-induced pruritus.

BACKGROUND: Activation of the serotonergic system is an important factor in the pathogenesis of intrathecal morphine-induced pruritus. Mirtazapine is a new antidepressant that selectively blocks 5-HT(2) and 5-HT(3) receptors. We therefore tested the hypothesis that preoperative mirtazapine would reduce the incidence of intrathecal morphine-induced pruritus. METHODS: One hundred and ten ASA I patients undergoing lower limb surgery under spinal anaesthesia were randomly allocated into two equal groups and received either mirtazapine 30 mg or an orally disintegrating placebo tablet 1 h before operation in a prospective, double-blinded trial. All patients received an intrathecal injection of 15 mg of 0.5% isobaric bupivacaine and 0.2 mg preservative-free morphine. The occurrence and the severity of pruritus were assessed at 3, 6, 9, 12, and 24 h after intrathecal morphine. RESULTS: Pruritus was significantly more frequent in the placebo group compared with the mirtazapine group (75% vs 52%, respectively; P=0.0245). The time to onset of pruritus in the two groups was also significantly different. The patients who experienced pruritus in the placebo group had a faster onset time than that in the mirtazapine group [mean (sd): 3.2 (0.8) vs 7.2 (4.1) h, P<0.0001]. CONCLUSIONS: Mirtazapine premedication prevents pruritus induced by intrathecal morphine in patients undergoing lower limb surgery with spinal anaesthesia.

Comparison of the effects of thoracic epidural analgesia and i.v. infusion with lidocaine on cytokine response, postoperative pain and bowel function in patients undergoing colonic surgery.

BACKGROUND: Both thoracic epidural analgesia (TEA) and i.v. lidocaine were able to decrease postoperative pain and duration of ileus. We compared TEA and i.v. lidocaine (IV) regarding their effects on cytokines, pain and bowel function after colonic surgery. METHODS: Sixty patients were randomly allocated to one of the three groups. TEA group had lidocaine 2 mg kg(-1) followed by 3 mg kg(-1) h(-1) epidurally and an equal volume of i.v. normal saline. The IV group received the same amount of lidocaine i.v. and normal saline epidurally. The control group received normal saline via both routes. These regimens were started 30 min before surgery and were continued throughout. Blood cytokines were measured at scheduled times within 72 h. RESULTS: Both TEA and IV groups had better pain relief. The total consumptions using patient-controlled epidural analgesia were 81.6 (6.5), 55.0 (5.3) and 45.6 (3.9) ml (P<0.01) and the times of flatus passage were 50.2 (4.9), 60.2 (5.8) and 71.7 (4.7) h (P<0.01) in the TEA, IV and control groups, respectively. The TEA group exhibited the best postoperative pain relief and the least cytokine surge. The IV group experienced better pain relief and less cytokine release than the control group. CONCLUSIONS: The TEA lidocaine had better pain relief, lower opioid consumption, earlier return of bowel function and lesser production of cytokines than IV lidocaine during 72 h after colonic surgery; IV group was better than the control group.