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Abstract

Background The bioreactance technique is a relatively new, totally non-invasive technique used to measure cardiac output that is easy to use. Non Invasive Cardiac Output Monitor (NICOM) is one such system (Cheetah Medical Inc). Although approved by FDA for measurement of stroke volume, there is a paucity of literature validating this technology in decompensated heart failure and cardiogenic shock (CS). Methods and Results Fifty patients admitted to our cardiac intensive care unit (CICU) for CS and Swan Ganz catheter guided therapy were prospectively enrolled in the study after informed consent. Simultaneous measurements of cardiac output (CO) were obtained using NICOM, indirect Fick (IF) and bolus thermodilution (TD). Intraclass correlation coefficient (ICC) was used to assess the precision of NICOM for CO using the three repeated measurements of CO over the pooled data. The agreement of the NICOM device in the defined clinical population compared to IF and TD, was evaluated by comparing the Pearson Correlation Coefficient, the Bland-Altman plot, and Lin’s Concordance Correlation Coefficient. ICC for cardiac output measured by NICOM showed excellent repeatability (ICC = 0.93, 95% CI = 0.92 – ۰٫۹۴, n = 262) in the pooled data. Pearson Correlation Coefficient for cardiac output measured by NICOM was poor when compared to IF (n = 263, r = 0.132, p = 0.033) and TD (n = 258, r = 0.275, p < 0.001). Conclusions NICOM technology is not a reliable method of measuring CO in patients with decompensated heart failure and CS.

Introduction

Invasive nature of pulmonary artery catheter (PAC) is often cited as an added risk to the patients with unclear mortality benefit among critically ill patients. [1,2] Eisenberg et al. and Mimoz et al. demonstrated that physicians could predict cardiac output with only 50% accuracy in the absence of direct hemodynamic data [3, 4], indicating the need for hemodynamic monitoring in critically ill patients. Current guidelines support the use of invasive hemodynamic monitoring in selected patients in whom a clinical evaluation does not provide sufficient data to determine optimal medical therapy. [5] For these reasons, measurement of cardiac output (CO) using non-invasive or minimally invasive devices has gained popularity. The bioreactance technique is a relatively new, non-invasive technique used to measure CO. Non Invasive Cardiac Output Monitor (NICOM) is one such system (Cheetah Medical Inc).