Effect of Systemic Vascular Resistance on the Reliability of Noninvasive Hemodynamic Monitoring in Cardiac Surgery

Objective: To assess the effect of systemic vascular resistance (SVR) on the reliability of the ClearSight system (Edwards Lifesciences, Irvine, CA) for measuring blood pressure (BP) and cardiac output (CO).Design: Observational study.Setting: University hospital.Participants: Twenty-five patients undergoing cardiac surgery.Interventions: None.Measurements and Main Results: BP, measured using ClearSight and an arterial line, and CO, measured using ClearSight and a pulmonary artery catheter, were recorded before (T1) and two minutes after phenylephrine or ephedrine administration. Bland-Altman analysis was used to compare BP and CO measurements at T1. A polar plot was used to assess trending abilities. Patients were divided into the following three groups according to the SVR index (SVRI) at T1: low (<1,200 dynes/cm(5)/m(2)), normal (1,200-25,00 dyne s/cm(5)/m(2)), and high (>2,500 dyne s/ cm(5)/m(2)). The bias in BP and CO was -4.8 +/- 8.9 mmHg and 0.10 +/- 0.81 L/min, respectively, which was correlated significantly with SVRI (p < 0.05). The percentage error in CO was 40.6%, which was lower in the normal SVRI group (33.3%) than the low and high groups (46.3% and 47.7%, respectively). The angular concordance rate was 96.3% and 95.4% for BP and 87.0% and 92.5% for CO after phenylephrine and ephedrine administration, respectively. There was a low tracking ability for CO changes after phenylephrine administration in the low-SVRI group (angular concordance rate 33.3%).Conclusion: The ClearSight system showed an acceptable accuracy in measuring BP and tracking BP changes in various SVR states; however, the accuracy of CO measurement and its trending ability in various SVR states was poor. (C) 2020 Elsevier Inc. All rights reserved.