Intravascular volume score using bedside ultrasound
Munie S, Kandagatla P, Blyden D, Dereczyk D, and Killu K. Intravascular volume score using bedside ultrasound. Crit Care Med 2019; 47(1).
Crit Care Med
Learning Objectives: Use of Bedside Ultrasound (BU) for assessment of volume status in the ICU has invaluable benefit for intensive care physicians. Current trends involve BU of single organs such as the Inferior Vena Cava (IVC) or heart. This study is an extension of earlier data looking at the use of multiple organ ultrasound exams to develop a scoring system (IV Score) for volume status, and comparing the system to the current standard methods of clinical diagnosis. Methods: A prospective, observational study at a single academic tertiary center was performed. Patients who underwent BU for volume assessment that also had invasive monitors and labs for a standard method (SM) measurement were included in this study. BU method included evaluating the heart, lungs, IVC and internal jugular vein (IJV). We developed an IV Score which consisted of the following parameters: A) Heart: Hyperkinetic=-1, Normal=0, hypokinetic=+1. B) Lungs: Absence of B-Lines=-1, 1-2 B-Lines=0, ≥3 B-Lines=+1. C) IVC: <2.5 cm and > 50% respiratory variation (RV) in diameter=-1, 1.5-2.5 cm, <50% RV=1, > 2.5 cm and <50% RV=+1. D) IJV: >40% RV=-1, 20-40% RV=1, <20%=+1. The IV score ranges from -4 to +4. Correlation between SM measurements and IV scores was evaluated by Spearman's correlation coefficient. ROC analysis was used to assess the ability of the IV score to detect hypovolemia. Results: Sixty-one patients were included in the study. Thirty-seven (61%) were male, 39 (64%) were Caucasian and mean age was 59 years±14. There were clear cut-off points to divide the total scores into the three categories of hypovolemia (score -2 to -4), euvolemia (-1 to 1) and hypervolemia (2 to 4). There was a strong correlation between IV score and SM of fluid status assessment, r=0.89, p<0.001. IV score was able to discriminate between hypovolemic and non-hypovolemic patients, AUC 0.97 (95% CI: 0.93-1.0), p<0.001. Using a cutoff of -2 on IV score has a 90.5% sensitivity and 95% specificity in determining hypovolemia. Conclusions: IV Score was found to strongly correlate with standard methods of volume assessment, with strong ability to discriminate hypovolemic patients from non-hypovlemic patients. An IV Score near zero indicates euvolemia, near -4 indicates hypovolemia and near +4 indicates hypervolemia.