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Abstract

Background: Spinal anesthesia is the preferred technique for cesarean sections due to its rapid onset, effective analgesia, and reduced risks compared to general anesthesia. However, spinal anesthesia failure can necessitate conversion to general anesthesia, posing significant clinical and medicolegal concerns. Various factors, including patient physiology, procedural conditions, and anesthetic expertise, contribute to failure. Understanding these determinants is essential for optimizing anesthesia management and improving maternal outcomes. This study aims to evaluate the frequency of failed spinal anesthesia in obstetric patients undergoing cesarean sections and identify associated risk factors.
Objective: To determine the incidence of failed spinal anesthesia in cesarean section patients and analyze its association with patient demographics, ASA classification, type of surgery, and body weight.
Methods: This prospective study was conducted over six months in the Anesthesiology Department of Khyber Teaching Hospital, Peshawar. A total of 203 obstetric patients scheduled for elective or emergency cesarean sections were enrolled using a non-probability consecutive sampling method. Spinal anesthesia was administered with hyperbaric bupivacaine (0.5%) using a standardized protocol. Failure was defined as a Visual Analog Scale (VAS) score >3 upon incision testing and a Modified Bromage Score >2 at 10 minutes post-administration. Data on age, ASA classification, type of cesarean section, and body weight were collected. Statistical analysis was performed using SPSS version 25, with chi-square tests assessing associations, considering a p-value <0.05 as statistically significant.
Results: Spinal anesthesia failed in 9 patients (4.4%) out of 203, while 194 (95.6%) had a successful block. Emergency cesarean sections exhibited a significantly higher failure rate of 7 (3.4%) compared to elective cases at 2 (1.0%) (p = 0.004). Patients weighing 71–75 kg had a higher failure incidence (6 cases, 3.0%) than those in the 65–70 kg range (3 cases, 1.5%) (p < 0.001). ASA classification did not significantly influence failure rates, with ASA I at 2 (1.0%), ASA II at 6 (3.0%), and ASA III at 1 (0.5%) (p = 0.18).
Conclusion: The study identified a low overall failure rate of spinal anesthesia, with emergency cesarean sections and higher patient weight as the primary risk factors. These findings emphasize the importance of tailored anesthetic approaches in high-risk cases to reduce failure rates and enhance maternal safety.