A pilot study on the role of autonomic function testing in predicting hypotension in patients undergoing cesarean section under spinal anesthesia

ABSTRACT

BACKGROUND: Maternal hypotension is a common complication during obstetric spinal anesthesia. This study was conducted to investigate the role of autonomic function testing in predicting maternal hypotension during spinal anesthesia induced to conduct Cesarean sections (C-section). METHODS: This study was conducted on 32 parturients undergoing C-section under spinal anesthesia. Sympathetic function tests included measuring diastolic blood pressure changes in response to hand gripping and systolic blood pressure changes response to moving from a supine to a standing position. Sympathetic dysfunction is said to exist when there are abnormal responses to both sympathetic function tests. Parasympathetic function tests included measuring heart rate responses to deep breathing and heart rate responses to moving from a supine to a standing position. Parasympathetic dysfunction is said to exist when there are abnormal responses to both parasympathetic function tests. After the onset of spinal anesthesia, blood pressure was measured every minute until childbirth. RESULTS: Hypotension occurred in 22 of the 32 parturients. There was no correlation between sympathetic dysfunction and hypotension incidence, but 12 of the 12 (100%) of the positive group and 10 of the 20 (50%) of the negative group experiencing parasympathetic dysfunction, respectively, experienced hypotension with a significant difference of P = 0.004. The group experiencing parasympathetic dysfunction had statistically significantly higher phenylephrine requirements were also greater in the parasympathetic dysfunction positive group (P < 0.003). CONCLUSIONS: This study's findings suggested that the parasympathetic function tests may be useful methods for predicting the incidence of maternal hypotension during spinal anesthesia induced for C-section.