A Comparison of Bioimpedance and Echocardiography in Measuring Cardiac Output in Healthy Male Volunteers

ABSTRACT

PURPOSE: To manage a critically ill patient effectively, an emergency physician must make an accurate assessment of the patient's hemodynamic status. Although the hemodynamic status can be accurately measured through the use of a pulmonary artery catheter, this device has significant limitations in the emergency department. Instead, the most commonly used method of measuring cardiac output (CO) in the emergency department is transthoracic echocardiography (TTE). However, TTE has been reported to underestimate the CO. Impedance cardiography (ICG) is an established and accurate technique for noninvasive determination of hemodynamic parameters. Thus, this study aimed to assess the agreement between CO measurements made by using TTE and ICG. METHODS: In 20 healthy volunteers, the hemodynamic parameters (stroke volume and CO) obtained by TTE were compared with the parameters derived from simultaneous measurements by ICG. RESULTS: The mean stroke volumes and COs were 63.9+/-11.6 ml and 4.1+/-0.7 L/min, respectively, by TTE, and 77.2+/-10.2 ml and 5.0+/-0.6 L/min by ICG. The correlation coefficients for stroke volume and CO between TTE and ICG were 0.77 and 0.64. The mean difference in stroke volume between TTE and ICG was -13.3+/-6.4 ml (-19.5+/-10.5 %), and the mean difference in CO was -0.88+/-0.48 L/min (-20.1+/-11.6 %). CONCLUSION: In healthy volunteers, the comparison between TTE and ICG showed a good correlation for stroke volume and CO. However, the mean differences in stroke volume and CO between TTE and ICG were -19.5+/-10.5 % and -20.1+/-11.6 %, respectively.