The relationship of back length and sagittal abdominal diameter with the level of sensorial block during spinal anesthesia for cesarean section: A prospective observational study

Purpose: In this study, we aimed to investigate the relationship of sensory block level with back length and sagittal abdominal diameter in spinal anesthesia for cesarean section using anthropometric measurements. Materials and Methods: This study was performed in a total of 45 patients between the ages of 18-40 years included in the ASA II classification. After the patients were admitted to the operating room and standard monitoring (heart rate, noninvasive blood pressure, peripheral oxygen saturation) was performed, abdominal circumference (AC) and sagittal abdominal diameter (SAD) were measured in the supine position. Height, weight, body mass index (BMI) and body roundness index (BRI) were recorded in all patients. Trunk length (TL) and back length (BL) were then recorded in the sitting position. 0.5% hyperbaric bupivacaine 2 ml was administered intrathecally with a 25 G Quincke needle at the L4-L5 level. The patients were turned to supine position and the level of sensory block, motor block, heart rate, blood pressure, amount of ephedrine used during the operation, frequency of hypotension, and complications such as nausea and vomiting were recorded. Results: The study was completed with 45 patients. There was no correlation between height, weight, BMI, BRI, TL, AC, BL, SAD values with maximum block level or hypotension (p>0.05). There was no correlation between BL, SAD and BL/SAD2 ratio with time to reach maximum sensory block level, T4 time and hypotension (p>0.05). However, there was a statistically significant negative correlation between the time to T4 of sensory block and BRI (r:-0.338, p<0.05), AC (r:-0.350, p<0.05), TL/AC2 (r:0.349, p<0.05). There was a significant positive correlation between the time to reach T4 sensory block and TL (r:0.442, p<0.01). There was a statistically significant negative correlation between the time to reach maximum sensory block and BRI (r:-0.300, p<0.05) and a statistically significant positive correlation with TL (r:0.550, p<0.01). In our study, TL, AC, BRI affected the rise time of sensory block, while body height, weight and BMI were not found to be related. Conclusion: In our study, it has been shown that three-dimensional anthropometric measurements are effective and stimulating parameters at the time of subarachnoid spread of spinal anesthesia and rise of sensory block level in pregnant women. Our study showed that in pregnant women, not the BL, which is the regional spine length, but the TL, which is the length of the entire spine, is more effective in mechanical compression of the spinal cord by the abdominal contents; therefore, it is not correct to evaluate the compression only mechanically. AC width and BRI height were also shown to be associated with rapidly increasing sensory block. In conclusion, AC width, TL shortness, and high BRI are warning parameters in terms of determining the risk for undesirable, rapidly rising block level after spinal anesthesia in pregnant women and taking necessary precautions. Since anthropometric measurements in pregnant women have many advantages such as being practical, fast and easy to perform, inexpensive and can be performed on the operating table, these measurements should be widespread.