Relationship of Abdominal Circumference and Trunk Length With Spinal Anesthesia Block Height in Geriatric Patients Undergoing Transurethral Resection of Prostate

Introduction: Spinal anesthesia is commonly used for various surgical procedures. Prediction of spinal anesthesia block height is always a challenging task for anesthetists. Higher than desired levels of spinal anesthesia blocks are associated with serious side effects, while inadequate block height does not provide satisfactory surgical anesthesia. In this study, we observed the relationship between the ratio of trunk length (TL) and square of the abdominal circumference (AC(2)) and spinal anesthesia sensory block height in geriatric patients undergoing transurethral resection of the prostate (TURP). Material & Methods: This is a cross-sectional study conducted at the Aga Khan University Hospital Karachi, Pakistan, on geriatric patients undergoing TURP under spinal anesthesia. Forty-three elderly patients (American Society of Anaesthesiology level I-III) between 60 and 80 years were recruited for the study. In hospital wards, trunk length (TL) and abdominal circumference were recorded before the procedure. In the operating rooms, spinal anesthesia was performed at L3-L4 intervertebral space with 0.5% hyperbaric bupivacaine 10mg (2mls). Block height was measured by the placement of ice pads at different dermatomes. Spearman rank correlation coefficient was used to analyze the physical parameters (TL/AC(2)) and spinal anesthesia block height. Results: The ratio of trunk length and square of the abdominal circumference (TL/AC(2)) correlates with spinal anesthesia block height in geriatric patients, where the spearman rank correlation coefficient was r =-0.284 with p = 0.015. Conclusion: The ratio of the long axis (TL) and transection area of the abdomen (AC(2)), which coincides with (TL/AC(2)), correlated with spinal anesthesia sensory block height. Hence, elderly patients with a low TL/AC(2 )ratio will have higher block height after spinal anesthesia.