[Spinal anesthesia in cesarean section: 1% versus 0.5% hyperbaric bupivacaine]

Abstract

Aim: To compare the quality of anesthesia produced by the intrathecal administration of equivalent doses of 0.5% and 1% hyperbaric bupivacaine in patients undergoing cesarian section.

Experimental design: A prospective, comparative and randomised clinical study.

Setting: Anesthesia Unit-Non-university civil hospital.

Patients: 50 patients undergoing elective or emergency cesarian section randomly assigned to two groups of 25 patients each.

Surgery: After prehydration, subarachnoid access was achieved through space L2-L3 or L3-L4 using a 24G Sprotte's needle with patients in right hand lateral decubitus. Patients in group A were injected with 1.25 ml of 1% hyperbaric bupivacaine and those in group B with 2.5 ml of 0.5% hyperbaric bupivacaine (12.5 mg). Patients were positioned immediately in partial decubitus on their left hand sides and ephedrine infusion, or if required i.v. bolus, was commenced to counter hypotension (SAP < 80% basal).

Measurements: ECG, pulse measurement, arterial pressure with non-invasive method, metameric level of analgesia (pin prick), motor block of lower limbs (Bromage's scale), time lapsed between induction of anesthesia and extraction of neonate, Apgar score, quantity of ephedrine used, duration of surgery, respiratory complications, insufficient analgesia, resolution of motor block, any postspinal cephalea.

Statistical analysis: Variance analysis, Student's t-test, chi 2.

Results: Both solutions guaranteed satisfactory intraoperative analgesia in 96% of cases. No statistically significant differences were noted between the two groups relating to the maximum duration of analgesia, the extent of motor block, induction times and regression, incidence of complications.

Conclusions: No important difference was observed in the quality of the anesthesia obtained using the intrathecal administration of equivalent doses of 1% and 0.5% solutions of hyperbaric bupivacaine in patients undergoing cesarian section. In view of the possible relationship between the neurotoxicity of local anesthetics and the concentration of the solution used for spinal anesthesia, it is to be hoped that less concentrated solutions of hyperbaric bupivacaine will be introduced in Italy compared to the 1% solution currently available.