LAUSR

Purpose: Measurement of inferior vena cava collapsibility (cIVC) by point‐of‐care ultrasound (POCUS) has been proposed as a viable, non‐invasive means of assessing fluid responsiveness. We aimed to determine the ability of cIVC to identify patients who will respond to additional intravenous fluid (IVF) administration among spontaneously breathing critically‐ill patients. Methods: Prospective observational trial of spontaneously breathing critically‐ill patients. cIVC was obtained 3 cm caudal from the right atrium and IVC junction using POCUS. Fluid responsiveness was defined as a ≥ 10% increase in cardiac index following a 500 ml IVF bolus; measured using bioreactance (NICOM™, Cheetah Medical). cIVC was compared with fluid responsiveness and a cIVC optimal value was identified. Results: Of the 124 participants, 49% were fluid responders. cIVC was able to detect fluid responsiveness: AUC = 0.84 [0.76, 0.91]. The optimum cutoff point for cIVC was identified as 25% (LR + 4.56 [2.72, 7.66], LR‐ 0.16 [0.08, 0.31]). A cIVC of 25% produced a lower misclassification rate (16.1%) for determining fluid responsiveness than the previous suggested cutoff values of 40% (34.7%). Conclusion: IVC collapsibility, as measured by POCUS, performs well in distinguishing fluid responders from non‐responders, and may be used to guide IVF resuscitation among spontaneously breathing critically‐ill patients. HIGHLIGHTSIVC collapsibility, as measured by POCUS, is able to detect fluid responsiveness.Use of a passive leg raise did not improve detection of fluid responsiveness.The optimum cutoff point for IVC collapsibility is cIVC = 25%.cIVC, measured by POCUS may be used to direct fluid resuscitation.