Assessment of left ventricular function by pulse wave analysis in critically ill patients

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.

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.

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).

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.