Intensivist Bedside Ultrasound (INBU) for Volume Assessment in the Intensive Care Unit: A Pilot Study

Abstract

Estimation of volume status in the high-acuity surgical population can be challenging. The use of intensivist bedside ultrasound (INBU) to rapidly assess volume status in the surgical intensive care unit (SICU) was hypothesized to be feasible and as accurate as invasive measures. Clinician sonographers (CSs) were trained to perform basic cardiac ultrasound and sonographic assessment of the inferior vena cava (IVC). A convenience sample of general surgery and trauma patients was enrolled in the SICU. The CS interpreted IVC and cardiac parameters and then categorized the subject as hypovolemic or not hypovolemic. Intensivists caring for the patients were blinded to the INBU findings and made a real-time expert clinical judgment (ECJ) of the patient's volume status (hypovolemic vs. not hypovolemic) using all available traditional data. A total of nine CSs performed 70 studies; three of the CSs performed the majority of the studies (86%). Adequate ultrasound (US) views for cardiac and IVC assessment were obtained in 96% and 89% of studies, respectively. The ECJ was considered to be the standard to which comparisons were made. The concordance rate between ECJ and central venous pressure was 62%. ECJ concordance with sonographic measures were similar (cardiac US = 75%, IVC US = 67%, and IVC collapse index = 65%). All pairwise comparisons against the ECJ/CVP agreement were not significantly different. INBU is feasible in the SICU and is equivalent to central venous pressure in assessing volume status. Noninvasive methods to assess volume status may decrease the need for invasive procedures.