Alternatives to Apical View in Predicting Fluid Responsiveness by Transthoracic Echocardiography: An Observational Study

Introduction: Flow analysis in the apical view of transthoracic echocardiography is validated to assess fluid responsiveness at the bedside. Still, it is not always reachable, especially in mechanically ventilated patients and during surgery. We compared it to supra-sternal and sub-xiphoid views to evaluate their validity in assessing fluid responsiveness in critically ill patients. Method: A cross-sectional prospective monocentric pilot study of three months duration has been led in the critical care unit for surgical emergencies of Ibn Sina University Hospital of Rabat (Morocco). We used the time-velocity index (VTI) and peak velocity variation (∆Vpeak) values correlation between the three acoustic windows as the main judgment criteria. Measurement of data was made in the Left Ventricle Outflow Tract (LVOT) in the 5-chamber apical view, Descending Thoracic Aorta (DTA) in the supra-sternal view, and Right Ventricle Outflow Tract (RVOT) in the sub-xiphoid view. Results: There were 14 adult patients involved in the study, and the data presented are preliminary results. There was no significant difference in VTI and ∆Vpeak values between the three acoustic windows at each time of the study protocol, with a very high correlation for initial VTI value between 5-chamber apical view and supra-sternal view (r = 0.96, p < 0.001), and sub-xiphoid view (r = 0.86, p < 0.001). A very high correlation of initial ∆Vpeak value was also observed between the 5-chamber apical view and supra-sternal view (rho = 0.89, p < 0.001) and sub-xiphoid view (rho = 0.79, p < 0.001). Discussion: Supra-sternal and sub-xiphoid views showed high potential to predict fluid responsiveness, but further data are needed to validate their use for this purpose in ICU and in operating room.