Relationship between pulse pressure variation and echocardiographic indices of left ventricular filling pressure in critically ill patients

BACKGROUND: Pulse pressure variation (PPV) is a dynamic index of fluid responsiveness. This parameter helps clinicians in improving haemodynamic status while avoiding potential fluid overload. Echocardiographic indices, such as E/E' ratio and left atrial (LA) strain by speckle tracking echocardiography (STE), are used to estimate left ventricular (LV) filling pressures. This study aimed at exploring the relationship between PPV and echocardiographic indices of LV filling pressures in critically ill patients. METHODS: Twenty-two patients (mean age of 50.9 ± 21.6, male/female = 15/7) admitted to intensive care unit, and requiring mechanical ventilation and invasive arterial pressure monitoring, were studied. In all patients, two independent operators assessed simultaneously PPV, using a pulse contour method, mean E/E' ratio and peak atrial longitudinal strain (PALS) by means of STE. PALS values were obtained by averaging LA segments measured in the 4-chamber and 2-chamber views (global PALS). RESULTS: A significant negative correlation was found between mean E/E' ratio and PPV (R(2) = -0.76; P<0.001). A positive correlation between global PALS and PPV was found (R(2) = 0.80, P<0.001). Mean global PALS of 26.2% demonstrated excellent accuracy (Area Under Roc Curve = 0.86, P<0.001), and good sensitivity (92%) and specificity (86%) in predicting a PPV >15%. CONCLUSION: In a group of mechanically ventilated patients PPV, derived from pulse contour analysis, and echocardiographic preload parameters were well correlated. Global PALS by STE provided better estimation of PPV than mean E/E' ratio. PALS seems a potential alternative to PPV in assessing fluid responsiveness in critically ill patients.