Purpose: Left ventricular (LV) performance is often quantified by echocardiography in critically ill patients. Pulse wave analysis (PWA) systems can also monitor cardiac function but in a continuous fashion. We compared echocardiographic and PWA-derived indices of LV function.
Methods: We enrolled 70 critically ill patients equipped with invasive arterial pressure monitoring who required echocardiography. We simultaneously assessed LV ejection fraction (LVEF), the rate of LV pressure rise during systole (dP/dt MAX) obtained with echocardiography (EC-dP/dt MAX), the ratio of effective arterial elastance to LV end-systolic elastance (E a/E es) determined by echocardiography, the dP/dt MAX estimated from the arterial pressure waveform (AP-dP/dt MAX) and the cardiac cycle efficiency (CCE) using PWA.
Results: Mean LVEF was 53 ± 18 % and CCE 0.16 ± 0.26. CCE was correlated linearly with LVEF (r = 0.88, 95 % CI 0.81 to 0.92, P < 0.001), and the dP/dt MAX values from the two techniques were linearly correlated (r = 0.93, 95 % CI 0.87 to 0.96, P < 0.001). There was minimal bias between the techniques for measurement of dP/dt MAX (23.7 mmHg/ms; 95 % CI -23.6 to 71.0). E a/E es and CCE were inversely correlated (r = -0.81, 95 % CI -0.88 to -0.71, P < 0.001). A CCE value of <0.07 predicted LVEF <40 % with a sensitivity of 0.93 and a specificity of 0.96 (AUC 0.98, 95 % CI 0.90 to 1.0, P < 0.001). A CCE value of >0.12 predicted LVEF ≥50 % with a sensitivity of 0.96 and a specificity of 0.82 (AUC 0.94, 95 % CI 0.87 to 1.0, P < 0.001). A CCE value <0.12 predicted E a/E es ≥1.3 with a sensitivity of 0.93 and a specificity of 0.89 (AUC 0.94, 95 % CI 0.83 to 1.0, P < 0.001).
Conclusions: PWA-derived variables provide relevant information on cardiac contractility and performance in critically ill patients. PWA provides an easy method for online hemodynamic evaluation in critically ill patients.