A Comparative Study on Influence of Epidural Volume Extension on the Block Characteristics of Subarachnoid Plain Bupivacaine for Lower Abdominal Surgeries

Background: Central neuraxial block is a common anaesthetic technique for lower abdominal surgeries. Epidural volume extension is a technique that involves the injection of saline into the epidural space immediately following intrathecal injection, after the institution of combined spinal-epidural anaesthesia. This technique has some advantages over general anaesthesia like a circumvention of laryngeal response to airway manipulation. It also provides an effective sensory and motor blockade. The aim of this study was to assess the influence of epidural volume extension on the block characteristics of subarachnoid plain bupivacaine administered for lower abdominal surgeries.

Results: All the forty-two patients recruited completed the study. The mean time to request for the first analgesia was significantly longer in group Subarachnoid plus Epidural volume extension (SEVE) (208.63 + 84.14 minutes) than in group Subarachnoid (S) (148.95 ± 40.55 minutes), P= 0.02. The maximum median level of sensory block was significantly higher in the Subarachnoid plus Epidural volume extension (SEVE) group compared with the Subarachnoid (S) group and this was recorded at the 8th minute; T4 (T4-T6), and T5 (T5-T7), respectively. (P=0.01). The mean time to reach T6 sensory level was significantly less in group Subarachnoid plus Epidural volume extension (SEVE); 6.00 + 1.80 minutes compared with group Subarachnoid (S); 7.00 + 1.10minutes. (P=0.04). The systolic and diastolic blood pressure, mean arterial pressure, pulse rate and peripheral oxygen saturation recorded during the duration of surgery was within normal limits in both Subarachnoid (S) and Subarachnoid plus Epidural volume extension (SEVE)groups. There was no statistically significant difference between the two groups. The side effects recorded were hypotension and shivering. Hypotension occurred in 19.0% of patients in both groups, while shivering occurred in 9.5% in group Subarachnoid plus Epidural volume extension (SEVE) and 4.8% in group Subarachnoid (S) (P=0.575).

Conclusion: This study showed that epidural volume extension when using intrathecal low dose plain bupivacaine for lower abdominal surgeries not only provided adequate sensory and motor block but also a prolongation of anaesthesia. The incidences of side effects noticed in both groups were low and similar. Therefore, this study underscores the relevance of epidural volume extension on the subarachnoid block characteristics.