Improving echographic monitoring of hemodynamics in critically ill patients: Validation of right cardiac output measurements through the modified subcostal window

Objective: We aimed to assess the usefulness of using the right ventricle outflow tract (RVOT) velocity-time integral (VTI) for echocardiographic monitoring of cardiac output compared to the gold standard, the VTI along the left ventricle outflow tract (LVOT). Design: Prospective observational study. Setting: A tertiary intensive care unit. Patients: 100 consecutive patients. Interventions: echocardiographic monitoring in critically ill patients. Main variables of interest: We used intraclass correlation coefficients (ICC) to compare echocardiographic measurements of LVOT VTI through apical window with RVOT VTI through the parasternal and modified subcostal windows and to assess interobserver reproducibility. Preplanned post hoc analyses compared the ICC between ventilated and nonventilated patients. Results: At the time of echocardiography, 44 (44%) patients were mechanically ventilated and 28 (28%) were receiving vasoactive drugs. Good-quality measurements were obtained through the parasternal short-axis and/or apical views in 81 (81%) patients and in 100 (100%) patients through the subcostal window. Consistency with LVOT VTI was moderate for RVOT VTI measured from the modified subcostal view (ICC 0.727; 95%CI: 0.62–0.808) and for RVOT VTI measured from the transthoracic view (0.715; 95%CI: 0.59–0.807). Conclusions: Measurements of RVOT VTI are moderately consistent with measurements of LVOT VTI. Adding the modified subcostal window allows monitoring RVOT VTI in all the patients of this selected cohort, even those under mechanical ventilation.