BACKGROUND: The intended physiologic response to a fluid bolus is an increase in stroke volume (SV). Several ultrasound (US) measures have been shown to be predictive. The best measure(s) in critically ill surgical patients remains unclear.
METHODS: This is a prospective observational study in critically ill surgical patients receiving a bolus of crystalloid, colloid or blood. A transthoracic echocardiogram was performed before (pre–transthoracic echocardiogram) and after. A positive volume response (+VR) was defined as a ≥15% increase in SV. Predictive measures were: left ventricular velocity time integral (VTI), respiratory SV variation (rSVV), passive leg raise SVV (plr SVV), positional internal jugular (IJ) vein change (0–90 degrees) and respiratory variation in the IJ sitting upright (90 degrees IJ). For each measure the area under the receiver operating curve (AUROC) was assessed and the best measure(s) determined.
RESULTS: Between November 2013 and November 2015, 199 patients completed the study. After the pilot analyses, plr SVV was abandoned because it could not be reliably assessed. VTI, rv 90 degrees IJ, 0 degree to 90 degrees IJ, were all significantly associated with VR (p < 0.05), rSVV and rv inferior vena cava were not. For VTI AUROC was 0.71 (95% confidence interval [CI], 0.64–0.77). For rv 90 degrees, it was 0.65 (95% CI, 0.57–0.71), and 0.61 (95% CI, 0.54–0.69) for 0 degrees to 90 degrees IJ. When VTI and rv 90 degrees were considered together, the AUROC rose to 0.76 (95% CI, 0.69–0.82) for the population as a whole and 0.78 (95% CI, 0.69–0.85) in mechanically ventilated patients. The positive predictive value for combined assessment was 80% and the negative 70%.
CONCLUSION: In a clinically relevant heterogeneous population, US is moderately predictive of VR. Inferior vena cava diameter change is not predictive. IJ change and VTI are the best measures, especially when used together. Future work should focus on combination metrics and the IJ.
LEVEL OF EVIDENCE: Diagnostic test, level II.
From the Department of Surgery (S.B.M., S.F., A.R.M., T.M.S.), University of Maryland School of Medicine, Baltimore, Maryland; Naval Medical Research Institute (J.J.G.), San Antonio, Texas; Department of Anesthesia (S.M.G.), University of Maryland School of Medicine; Department of Medicine (S.B.), University of Maryland School of Medicine, Baltimore, Maryland; U.S. Air Force Center for Sustainment of Trauma and Readiness Skills (R.F.); and Department of Epidemiology and Public Health (H.C.), University of Maryland School of Medicine, Baltimore, Maryland.
Submitted: February 9, 2016, Revised: October 4, 2016, Accepted: October 10, 2016, Published online: December 28, 2016.
This study was presented at the 29th annual meeting of the Eastern Association for the Surgery of Trauma, January 12–16, 2016, in San Antonio, Texas.
Address for reprints: Sarah B. Murthi, MD, The R. Adams Cowly Shock Trauma Center, Baltimore, MD; email: firstname.lastname@example.org.