# Feasibility of continuous high-resolution bioreactance monitoring during cesarean delivery under spinal anesthesia

## TL;DR

This study shows that high-resolution bioreactance monitoring during cesarean delivery is feasible and can detect early signs of hemodynamic changes before hypotension occurs.

## Contribution

The first study to use bioreactance monitoring with 4-second intervals during cesarean delivery under spinal anesthesia.

## Key findings

- A stroke volume index (SVI) decline of ≥20% occurred in 29 out of 51 patients.
- SVI changes preceded hypotension by an average of 2 minutes and 20 seconds.
- Monitoring provided stable data with less than 0.5% signal loss.

## Abstract

This study is the first to apply bioreactance-based hemodynamic monitoring with a 4-s interval during cesarean delivery under spinal anesthesia. We evaluated the feasibility of continuous, high-resolution perioperative monitoring in a routine clinical setting, with a particular focus on the temporal relationship between hypotension and changes in advanced hemodynamic parameters.

This prospective observational study conducted between December 2023 and April 2024 included 51 healthy parturients scheduled for elective cesarean delivery under spinal anesthesia were included. All participants underwent continuous non-invasive hemodynamic monitoring using bioreactance technology. Hemodynamic parameters were recorded at 4-s intervals. The primary outcome was the relative change in the stroke volume index (SVI) from baseline. The secondary endpoints included signal quality, data integrity, and trends in hemodynamic parameters.

A reduction in the stroke volume index (SVI) of ≥20% was observed in 29 of 51 patients. The median percentage change in SVI from baseline was −18.9% [IQR − 31.5 to −6.1]; p < 0.001. The median time from the onset of relevant SVI decline to the occurrence of hypotension was 2:20 min [IQR 1:16–3:56]. The total cumulative observation time for all patients was 3,781 min. At a 4-s sampling interval, approximately 56,713 data points per hemodynamic parameter were expected. The signal loss was minimal, with less than 0.5% missing data per parameter.

This method proved to be feasible and yielded stable, high-resolution hemodynamic data. Among all parameters, SVI showed the most consistent baseline values prior to anesthesia. It also demonstrated the most pronounced change, with a statistically significant decline in the majority of subjects between spinal anesthesia and the onset of first hypotension. In such cases, the marked decline in SVI may serve as an early indicator of impending hemodynamic compromise. These results from a low-risk obstetric cohort may inform future research on high-risk populations.