Noninvasive Cardiac Output Measurement in Shock Patients

ABSTRACT

PURPOSE: Invasive determination of cardiac output (CO) is possible via a pulmonary artery catheter but catheter implantation has risks. Clinicians can assess CO safely using a non-invasive cardiac output device such as a commercially available doppler system (ultrasonic cardiac output monitor, USCOM, USCOM Ltd, Australia) or using impedance cardiography (ICG). The purpose of this study was to investigate the consistency of hemodynamic measurements between ICG and USCOM in shock patients. METHODS: From June 2007 to October 2007, we prospectively evaluated 21 patients with shock, who visited our emergency center. We measured CO and systemic vascular resistance (SVR) using ICG and USCOM on arrival, and at 30, 60, 90, and 120 minutes. RESULTS: The mean difference in CO between ICG and USCOM was 1.08+/-2.13 L/min. The percent limits of agreement (LOA) were -60.0 to 84.7% between ICG and USCOM. The correlation coefficient for CO between ICG and USCOM was 0.76 (p<0.01). CO values measured by ICG and USCOM were 4.3+/-1.7 vs 5.9+/-3.9 initially, 4.8+/-2.2 vs 6.0+/-3.9 at 30 min, 4.3+/-1.6 vs 5.1+/-2.9 at 60 min, 4.2+/-1.6 vs 4.9+/-2.7 at 90 min, and 4.1+/-1.6 vs 5.0+/-2.9 at 120 min, respectively. Statistical significance was observed within each modalities (p=0.03) but we did not find statistical significances between the two modalities. SVR (dynes*sec/cm5) values were measured by ICG and USCOM on arrival, and at 30, 60, 90, and 120 minutes. No statistical significance was seen within and between study groups. CONCLUSION: ICG and USCOM do not show clinically acceptable agreement.