Finger cuff versus invasive and noninvasive arterial pressure measurement in pregnant patients with obesity.

Abstract

Background: Pregnant patients with obesity may have compromised noninvasive blood pressure (NIBP) measurement. We assessed the accuracy and trending ability of the ClearSight™ finger cuff (FC) with invasive arterial monitoring (INV) and arm NIBP, in obese patients having cesarean delivery.

Methods: Participants were aged ≥18 years, ≥34 weeks gestation, and body mass index (BMI) ≥ 40 kg m^-2. FC, INV, and NIBP measurements were obtained across 5-min intervals. The primary outcome was agreement of FC measurements with those of the reference standard INV, using modified Bland-Altman plots. Secondary outcomes included comparisons between FC and NIBP and NIBP versus INV, with four-quadrant plots performed to report discordance rates and evaluate trending ability.

Results: Twenty-three participants had a median (IQR) BMI of 45 kg m^-2 (44-48). When comparing FC and INV the mean bias (SD, 95% limits of agreement) for systolic blood pressure (SBP) was 16 mmHg (17, -17.3 to 49.3 mmHg), for diastolic blood pressure (DBP) -0.2 mmHg (10.5, -20.7 to 20.3), and for mean arterial pressure (MAP) 5.2 mmHg (11.1, -16.6 to 27.0 mmHg). Discordance occurred in 54 (26%) pairs for SBP, 41 (23%) for DBP, and 41 (21.7%) for MAP. Error grid analysis showed 92.1% of SBP readings in Zone A (no-risk zone). When comparing NIBP and INV, the mean bias (95% limits of agreement) for SBP was 13.0 mmHg (16.7, -19.7 to 29.3), for DBP 5.9 mmHg (11.9, -17.4 to 42.0), and for MAP 8.2 mmHg (11.9, -15.2 to 31.6). Discordance occurred in SBP (84 of 209, 40.2%), DBP (74 of 187, 39.6%), and MAP (63 of 191, 33.0%).

Conclusions: The FC and NIBP techniques were not adequately in agreement with INV. Trending capability was better for FC than NIBP. Clinically important differences may occur in the setting of the perfusion-dependent fetus.