Abdominal girth and vertebral column length can adjust spinal anesthesia for lower limb surgery, a prospective, observational study

BACKGROUND: Studies have shown that abdominal girth and vertebral column length have high predictive value for spinal spread after administering a dose of plain bupivacaine. we designed a study to identify the specific correlations between abdominal girth, vertebral column length and a 0.5 % dosage of plain bupivacaine, which should provide a minimum upper block level (T(12)) and a suitable upper block level (T(10)) for lower limb surgeries. METHODS: A suitable dose of 0.5 % plain bupivacaine was administered intrathecally between the L(3) and L(4) vertebrae for lower limb surgeries. If the upper cephalad spread of the patient by loss of pinprick discrimination was T(12) or T(10), the patient was enrolled in this study. Five patient variables and intrathecal plain bupivacaine dose were recorded. Linear regression and multiple regression analyses were performed. RESULTS: Totals of 111 patients and 121 patients who lost pinprick discrimination at T(12) and T(10), respectively, were analyzed in this study. Linear regression analysis showed that only abdominal girth and plain bupivacaine dose were strongly correlated (r =−0.827 for T(12,) r = −0.806 for T(10;) both p < 0.0001). Multiple linear regression analysis showed that both abdominal girth and vertebral column length were the key determinants of plain bupivacaine dose (both p < 0.0001). R(2) was 0.874 and 0.860 for the loss of pinprick discrimination at T(12) and T(10), respectively. CONCLUSIONS: Our data indicated that vertebral column length and abdominal girth were strongly correlated with the dosage of intrathecal plain bupivacaine for the loss of pinprick discrimination at T(12) and T(10). The two regression equations were Y(T12) = 3.547 + 0.045X(1)-0.044X(2) and Y(T10) = 3.848 + 0.047X(1)- 0.046X(2) (Y, 0.5 % plain bupivacaine volume; X(1), vertebral column length;and X (2), abdominal girth), which can accurately predict the minimum and suitable intrathecal bupivacaine dose for lower limb surgery to a great extent, separately.