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

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.

Diagnostic Value of the Brugada Algorithm in Differential Diagnosis of Wide QRS Tachycardia by Electrocardiogram

PURPOSE: In dealing with wide-complex tachycardia (WCT), it is important to distinguish between ventricular tachycardia (VT), supraventricular tachycardia with aberrancy (SVTAC), and preexcited tachycardia by using an accessory pathway. The aim of this study was to investigate and compare the Brugada and the Bayesian algorithms and to analyze the parameters. METHODS: Between January 1999 and December 2003, the Brugada and the Bayesian approaches were retrospectively analyzed in 103 WCTs confirmed by electrophysiologic studies. RESULTS: Seven-eight (75) VTs and 25 SVTs were found. The sensitivity and the specificity for VT achieved by using the Brugada approach were 91.0 and 68.0%, respectively, whereas those achieved by using the Bayesian approach were 84.6 and 60.0%. In the Brugada approach, the most important step was the fourth step (odds ratio: 4.33; 95% CI: 1.75-12.14). In the Bayesian approach, triphasic rsR' or rR' morphology (odds ratio: 3.93; 95% CI: 1.46-10.56), r > or = 0.04 s or notched S downstroke or delayed S nadir > 0.06 s in the V1 or the V2 lead (odds ratio: 5.75; 95% CI: 1.26?26.28), and intrinsicoid deflection > or = 0.08 s in the V6 lead (odds ratio: 6.88; 95% CI: 1.33-27.79) were more important parameters. Seven (7) VTs of 103 tachycardias were mis-classified when the Brugada approach was used. Applying additional criteria (QRS width > 0.16 s and intrinsicoid deflection > or = 0.08 s in V6 lead), three of those VTs were diagnosed correctly. CONCLUSIONS: The Brugada algorithm achieved a lower sensitivity and specificity than those reported by Brugada et al. If both the V1 and the V6 leads do not fulfill the criteria for VT, additional parameters should be evaluated.