The effect of height and weight adjusted dose of intrathecal hyperbaric bupivacaine for elective caesarean section.

INTRODUCTION The study compared spinal anesthesia using intrathecal hyperbaric bupivacaine between height and weight adjusted dose and fixed dose during caesarean section. METHODS A hundred parturients, who had given their consent and were scheduled for elective caesarean section under spinal anesthesia, were randomly assigned into two groups. We adjusted the intrathecal dose of heavy bupivacaine (0.5%) according to the height and weight of patients (Group AD) from Harten's dose chart developed from the Caucasian parturients and the fixed dose (2.2 ml) was used in Group FD patients. Keeping the observer blinded to the study groups, the onset time to sensory block up to T5, haemodynamic changes, side effects, and fetal outcome were observed. RESULTS The median onset time of spinal block in Group FD was faster than in Group AD (6 min vs. 4 min; p = 0.01). The spinal block level extended above T3 level in a significantly (p < 0.05) larger number of patients 12 (24%) in Group FD than in one (2%) patient in Group AD. A significantly (p < 0.05) larger number of patients, 32, (64%) in Group FD had hypotension than in 15 (30%) patients in Group AD. The lowest recorded SAP (101 +/- 6 mm Hg) in Group AD was higher than in Group FD (96 +/- 6.7 mm Hg). Nausea and vomiting were more pronounced in Group FD patients. CONCLUSIONS The bupivacaine dose was significantly reduced on its dose adjustment for the body weight and height of patients for cesearean section. This adjusted-dose use suitably restricted spinal block level for cesarean section with a distinct advantage of less hypotension and with a similar neonatal outcome as fixed compared with the dose use.