Evaluation of cardiac function index as measured by transpulmonary thermodilution as an indicator of left ventricular ejection fraction in cardiogenic shock.

Introduction: The PiCCO transpulmonary thermodilution technique provides two indices of cardiac systolic function, the cardiac function index (CFI) and the global ejection fraction (GEF). Both appear to be correlated with left ventricular ejection fraction (LVEF) measured by echocardiography in patients with circulatory failure, especially in septic shock. The aim of the present study was to test the reliability of CFI as an indicator of LVEF in patients with cardiogenic shock.

Methods: In thirty-five patients with cardiogenic shock, we performed (i) simultaneous measurements of echocardiography LVEF and cardiac function index assessed by transpulmonary thermodilution (n=72) and (ii) transpulmonary thermodilution before/after increasing inotropic agents (n=18).

Results: Mean LVEF was 31% (+/-11.7), CFI 3/min (+/-1), and GEF 14.2% (+/-6). CFI and GEF were both positively correlated with LVEF (P<0.0001, r2=0.27). CFI and GEF were significantly increased with inotropic infusion (resp., P=0.005, P=0.007). A cardiac function index<3.47/min predicted a left ventricular ejection fraction≤35% (sensitivity 81.1% and specificity 63%). In patients with right ventricular dysfunction, CFI was not correlated with LVEF.

Conclusion: CFI is correlated with LVEF provided that patient does not present severe right ventricular dysfunction. Thus, the PiCCO transpulmonary thermodilution technique is useful for the monitoring of inotropic therapy during cardiogenic shock.