Abdominal girth, vertebral column length and spread of intrathecal hyperbaric bupivacaine in the term parturient.

BACKGROUND: We aimed to test whether abdominal girth and vertebral column length were predictors of spinal hyperbaric bupivacaine spread in term parturients.

METHODS: A total of 128 parturients having elective caesarean section under spinal anaesthesia were enrolled. Combined spinal-epidural anaesthesia was performed at the L3/4 interspace, confirmed by ultrasonography. Two mL of 0.5% hyperbaric bupivacaine was injected intrathecally and spinal spread assessed at three-minute intervals. If loss of discrimination of pinprick sensation at the T6 level was not obtained within 15min after injection, 5mL of 2% lidocaine was administered epidurally. Correlation and multiple linear regression were used to analyse the relationship between patient variables, including age, height, weight, abdominal girth, vertebral column length and neonatal biparietal diameter, and the spread of spinal anaesthesia.

RESULTS: Two parturients were excluded. Significant univariate correlation with spinal spread existed for height, weight, abdominal girth and vertebral column length (r=-0.446, 0.201, 0.372, P<0.711, respectively, all P<0.05). Multiple linear regression analysis showed that parturients' abdominal girth and vertebral column length were the key determinants of spinal spread (both P<0.0001). The adjusted R2 was 0.742 for the regression equation between abdominal girth, vertebral column length and height of block.

CONCLUSION: Parturient abdominal girth and vertebral column length have significant predictive value in determining the cephalad spread of spinal anaesthesia with hyperbaric bupivacaine in term parturients.