Correlation between spinal column length and the spread of subarachnoid hyperbaric bupivacaine in the term parturient : original research

Background : Anaesthetists frequently tailor the subarachnoid local anaesthetic dosage according to parturient height to achieve sensory blockade up to the T4 dermatome for lower segment Caesarean sections (LSCSs). Studies that have been conducted have demonstrated that height does not affect the spread of subarachnoid hyperbaric bupivacaine. This study aimed to find the correlation between the spinal column length of term parturients and the highest level of sensory blockade after spinal anaesthesia. Methods : The authors studied 60 singleton term parturients of American Society of Anesthesiologists (ASA) physical status I or II scheduled for elective LSCSs. The length of the spinal column was taken as an average of three measurements from the C7 spinous process to the sacral hiatus in a sitting upright and facing forward position. Spinal anaesthesia was given by administering 1.8 ml of 0.5% hyperbaric bupivacaine and 25 g fentanyl through the L3/L4 or L4/L5 intervertebral space. The level of sensory blockade was assessed using pin-prick testing for pain sensation. Linear regression analysis was used to analyse the correlation; R < 0.25 indicates no correlation with the level of significance being < 0.05. Results : The spinal column lengths measured were between 42.2 cm and 85.8 cm (median : 58.5 cm). Spinal anaesthesia given was adequate for all patients, with the highest levels of anaesthesia ranging from T8 to T2 with sensory levels between T6 and T4. The parturients' spinal column length showed no correlation with the highest level of sensory blockade achieved, namely R = 0.11. Conclusions : The study found no correlation between the parturients' spinal column length and the highest level of sensory blockade achieved.