Vertebral column length and abdominal girth as predictors for cephalad spread of intrathecal hyperbaric bupivacaine: A prospective observational study

INTRODUCTION: In recent literature, there is some suggestion of vertebral column length (VCL) and abdominal girth (AG) in determining cephalad spread of spinal anesthetic. Bodily habitus including abdominal fat distribution, AG, and VCL may vary among individuals from different races/ethnicity. We thus aimed to evaluate the role of AG, and VCL measured with the patient in sitting as well as lateral position, in determining the cephalad spread of intrathecal hyperbaric bupivacaine. METHODS: Prospective blinded study conducted in 60 consenting adult male patients of ASA status I or II, undergoing lower limb surgery using standardized combined spinal epidural performed. The cephalad spread of subarachnoid block was assessed using loss of discrimination to pin-prick and cold temperature. The VCL was measured from C7 vertebra to the sacral hiatus in sitting as well lateral decubitus position. The AG was measured at level of umbilicus during end of expiration. RESULTS: The mean AG and VCL in sitting/lateral positions were: 78.4 ± 11.0, 60.9 ± 3.2, and 59.2 ± 3.2 cm, respectively. VCL in sitting position was significantly longer than in lateral position (P = 0.000). There was no significant correlation between the Smax (pin-prick) and AG (P = 0.138), or VCL in sitting position (P = 0.549), or VCL in lateral position (P = 0.323). Similar lack of correlation was noted with the Smax (cold) as well (P > 0.05). CONCLUSIONS: Contribution of AG or VCL on the extent of intrathecal drug spread is not a consistent finding.