SHoC-IVC: Does assessment of the inferior vena cava by point of care ultrasound independently predict fluid status in spontaneously breathing patients with undifferentiated hypotension?

Abstract

Abstract Background Accurately determining the fluid status of a patient during resuscitation in the emergency department (ED) helps guide appropriate fluid administration in the setting of undifferentiated hypotension. Our goal was to determine the diagnostic utility of point of care ultrasound (PoCUS) for inferior vena cava (IVC) size and collapsibility in predicting a volume overload fluid status in spontaneously breathing hypotensive ED patients. Methods This was a post-hoc secondary analysis of the SHOC-ED data, a prospective randomized controlled trial investigating PoCUS in patients with undifferentiated hypotension. We prospectively collected data on IVC size and collapsibility for 138 patients in the PoCUS group using a standard data collection form, and independently assigned a fluid status (volume overloaded, normal, volume deplete) from a composite clinical chart review blinded to PoCUS findings. The primary outcome was the diagnostic performance of IVC characteristics on PoCUS in the detection of an volume overloaded fluid status. Results 129 patients had completed determinant IVC assessment by PoCUS, with 125 receiving successful final fluid status determination, of which 107 were classified as volume deplete, 13 normal, and 7 volume overloaded. A receiver operating characteristic (ROC) curve was plotted using several IVC size and collapsibility categories. The best overall performance utilized the combined parameters of a dilated IVC (> 2.5cm) with minimal collapsibility (less than 50%) which had a sensitivity of 85.7% and specificity of 86.4% with an area under the curve (AOC) of 0.92 for predicting an volume overloaded fluid status. Conclusion IVC PoCUS is feasible in spontaneously breathing hypotensive adult ED patients, and demonstrates potential value as a predictor of a volume overloaded fluid status in patients with undifferentiated hypotension. IVC size may be the preferred measure.