Non-Invasive Monitoring Based on Bioreactance Reveals Significant Hemodynamic Instability during Elective Cesarean Delivery under Spinal Anesthesia

Background and objectives

Blood pressure monitoring offers a limited understanding of the hemodynamic consequences of spinal anesthesia for cesarean delivery. The purpose of this study was to assess, with the aid of a non-invasive cardiac output monitor based on bioreactance, the hemodynamic changes during elective cesarean delivery under spinal anesthesia in which intermittent boluses of phenylephrine were used to prevent and treat hypotension.

Methods

This observational study was conducted with the Research Ethics Board approval, and all participants provided written informed consent. Healthy patients undergoing elective cesarean delivery under spinal anesthesia were enrolled. Intermittent boluses of phenylephrine were administered in an attempt to maintain systolic blood pressure at baseline levels, and patients were assessed with a non-invasive cardiac output monitor based on bioreactance. Hemodynamic data was collected continuously at baseline, and during the postspinal and postdelivery periods. Data was analyzed using a mixed model ANOVA, and a p < 0.05 was considered significant.

Results

Systolic blood pressure was maintained within 79.2 ± 14.2 and 105.8 ± 10.0 percent of baseline during the postspinal period, and 78.4 ± 11.3 and 100.9 ± 10.7 percent of baseline in the postdelivery period (mean ± SD) There were significant fluctuations in systolic blood pressure, heart rate, and cardiac output during the postspinal period, and significant fluctuations in systolic blood pressure and cardiac output in the postdelivery period.

Conclusions

A new non-invasive monitor based on bioreactance reveals significant hemodynamic fluctuations during cesarean delivery under spinal anesthesia, despite attempts to maintain blood pressure at baseline levels with intermittent boluses of phenylephrine.