Blood pressure measurement during cesarean delivery: Evaluation of a beat-to-beat noninvasive device (NexfinTM)

BACKGROUND: Early detection of arterial hypotension during cesarean
delivery under spinal anesthesia is important. This study aims to compare
the validity of NexfinTM as beat-to-beat noninvasive blood pressure
monitoring with conventional intermittent oscillometric measurement of
blood pressure during elective cesarean delivery. METHODS: This open
prospective observational bicentric study was performed between January
2013 and December 2015. We simultaneously recorded arterial blood pressure
with both techniques in pregnant women undergoing elective cesarean
delivery under spinal anesthesia. The primary outcome was a Bland-Altman
analysis of systolic blood pressure measurement comparing NexfinTM and a
conventional method. The secondary outcomes were the time to detect the
first relevant hypotensive episode and the comparison of both devices
using a four quadrant graph. RESULTS: One hundred and seventy-four
parturients completed the study, and 2640 pairs of systolic blood pressure
measurements were analyzed. Bias was -10 mmHg with upper and lower limits
of agreement of -61 and +41 mmHg. In 73.9% of the cases, the two
techniques provided the same information (normotension or hypotension),
but the conventional method missed 20.8% of measurements, with NexfinTM
detecting 16.2% more hypotensive measurements. The median [25-75
percentiles] duration to detect the first hypotensive measurement was 331
[206-480] seconds for NexfinTM and 440 [300-500] seconds for intermittent
oscillometry (p<0.001). CONCLUSIONS: The agreement between NexfinTM
and an intermittent method for the measurement of systolic blood pressure
was not in an acceptable range during cesarean delivery, although NexfinTM
may detect hypotension earlier than the standard method.