Detection of hypotension during Caesarean section with continuous non-invasive arterial pressure device or intermittent oscillometric arterial pressure measurement

Abstract

Background: The intensified use of spinal anaesthesia (SPA) for Caesarean section significantly contributed to a decreased maternal mortality and morbidity. Nevertheless, one of the major side-effects is hypotension after SPA with potential negative effects on the fetus. Owing to discontinuous oscillometric measurements (non-invasive arterial pressure, NIAP), hypotensive episodes may be missed. Recently, a continuous NIAP measurement device (CNAP) with acceptable agreement with the mean invasive AP was introduced. We hypothesized that CNAP detects hypotensive episodes more reliably compared with NIAP measurements.

Methods: A total of 65 women undergoing Caesarean section under SPA were included in the study analysis. A total of 888 NIAP measurements obtained at 3 min cycles, starting from before SPA and continued until delivery, were analysed.

Results: When averaged over all cycles, the lowest systolic AP identified by CNAP in each cycle [105 mm Hg, (24.4)] was significantly lower (P<0.001) than the average of the individual corresponding single NIAP measurements [126 mm Hg (22.1)] and highest CNAP average [126 mm Hg (24.5)]. Hypotension (systolic AP <100 mm Hg) was detected in 39% of all cycles with CNAP and in 9% with NIAP. Hypotension was detected in 91% of the patients based on CNAP and in 55% based on NIAP. Fetal acidosis defined by an umbilical vein pH under 7.25 did not occur when the lowest systolic AP measured by CNAP was above 100 mm Hg.

Conclusions: The CNAP device detected more hypotensive episodes after SPA and significantly lower AP compared with NIAP. AP monitoring based on CNAP may improve haemodynamic management in this patient population with potential benefit for the fetus.