Background: Predictability of the extent of spinal anesthesia by plain bupivacaine has been controversial.
Methods: Two hundred and twenty-eight patients undergoing elective surgery with spinal anesthesia were enrolled in this retrospective study. Using gender, age, height, body mass index (BMI), chosen spinal interspace for spinal tap (L2-3 or L3-4), and dose of plain bupivacaine as independent variables, we performed stepwise multiple linear regression analysis to examine predictability of the extent of sensory blockade produced by spinal anesthesia using plain bupivacaine.
Results: Following equation was obtained. Extent of sensory blockade = 14.9 + (male : 0.540, female: -0.540) -0.0774 x height + 0.124 x BMI + (L2-3 : 0.345, L3-4: -0.345): r2 = 0.0604. P values of gender, height and BMI were less than 0.05; however, r2 of each variable was very low.
Conclusions: Results of this retrospective study imply the unpredictability of the extent of spinal anesthesia produced by plain bupivacaine.