Nalbuphine by PCA-pump for analgesia following hysterectomy: bolus application versus continuous infusion with bolus application.

ABSTRACT

The analgesic properties of the partial agonist-antagonist nalbuphine in the postoperative period are well known. When used for patient-controlled analgesia (PCA) the effectiveness of this substance is comparable to that of morphine or tramadol. However, the optimal programme for administration of nalbuphine in PCA-pumps has not been investigated. In particular, the combination of bolus administration vs bolus administration plus continuous basal administration is disputable. We hypothesized that the administration of an extra basal rate of nalbuphine in addition to the patient- triggered bolus administration and supplemental doses of diclofenac when required, would lead to a significant improvement in analgesia, without affecting the differences in vital signs and side effects. After approvement by the institutional ethics committee, 50 female patients (ASA I or II) scheduled for elective hysterectomy were included in a prospective, single-blinded study and randomized either into bolus-continuous (BC-)group (3 mg base rate/h, 1 mg bolus, 20 min lock out) or bolus (B-)group (no base rate, 1 mg bolus, 10 min lock out). During the observation period (up to 24 h postoperative) vital parameters, extent of analgesia (10-step VAS), and vigilance (5-step scale) were registered. Groups were compared by using unpaired Student t-test. A p<0.05 was considered to be significant. No differences were found in demographic data or vital parameters (MAP, PaO2, PaCO2, respiratory rate, heart rate, peripheral SaO2) during the observation period. Vital parameters showed no pathological changes in any group. With an identical rate of requirement for diclofenac (32 and 36%), analgesia in BC-group showed a decrease in VAS from 4.28+/-2.11 to 2.04+/-1.21 and from 3.64+/-2.20 to 2.08+/-0.96 in B-group. Vigilance was only marginally diminished in both groups. No serious side effects were found in either group. The consumption of nalbuphine (mg) was significantly higher in BC-group (70.28+/-13.85 vs. 47.44+/-22.99;p =0.0002) when compared to B-group. Subjective rating of effectiveness by the patients was similar in both groups. The two administration settings of nalbuphine by PCA pump have shown to be equally effective in the treatment of postoperative pain following hysterectomy. However, as the total amount of nalbuphine was significantly lower in B-group, the use of this administration schedule should be encouraged.