E55 - Echocardiographic Assessment of Fluid-responsiveness in Critically Ill Newborn Foals: A Pilot Study

Abstract: Background: Intravenous fluid requirements are difficult to estimate accurately on a clinical basis in critically ill newborn foals (CINF). Transthoracic echocardiography may help monitoring fluid responsiveness in these patients.

Hypothesis/Objectives: To study echocardiographic changes before and after a replacement fluid therapy in CINF.

Animals: Prospective observational study. Eight CINF less than three days old suffering of various neonatal diseases (sepsis, neonatal syndrome, prematurity) were enrolled.

Methods: On admission, unsedated CINF underwent a complete (M-mode, two-dimensional and Doppler) transthoracic echocardiography obtained from a right parasternal and subcostal views before any treatment. Conventional techniques/formulas were applied for the estimation of left ventricular volumes, fractional shortening, ejection fraction, stroke volume and cardiac output. An identical echocardiographic assessment was repeated at the end of a fluid challenge (Ringer's lactate, 10-20 ml/kg boluses). Comparison of echocardiographic parameters obtained before and after fluid therapy was made using a Wilcoxon signed rank test. A p-value < 0.05 was considered statistically significant.

Results: In all foals, initial echocardiographic variables overall indicated volume depletion. After fluid therapy (1-4 boluses), a statistically significant increase of left atrial size, left ventricular volumes, stroke volume and cardiac output was documented (Table 1). Remaining echocardiographic changes did not change significantly.

Conclusions and clinical importance: In CINF, many echocardiographic variables change after fluid bolus therapy, overall indicating a correction of volume depletion and an improvement of stroke volume and cardiac output. Integrating transthoracic echocardiography in the pre- and post-fluid therapy assessment of CINF may allow a better evaluation of fluid responsiveness and optimal titration.