Ultrasound of the inferior vena cava does not predict hemodynamic response to early hemorrhage

Background: Ultrasonographic evaluation of the inferior vena cava (IVC) provides information on central hemodynamics and predicts fluid responsiveness during positive pressure ventilation. In spontaneously breathing patients, the correlations between IVC dynamics and the hemodynamic response to volume shifts remain to be described.

Objectives: We aimed to describe the correlation between IVC dynamics and the changes in cardiac output (CO) caused by controlled hemorrhage.

Methods: Healthy donors from the blood bank were eligible for inclusion. Measurements of the IVC and CO were performed before and immediately after blood donation using ultrasound methods. A control group served to evaluate the effect of resting.

Results: Thirty-seven participants completed the study. IVC collapsibility index (IVC-CI) and IVC end expiratory diameter (IVCe) both changed significantly after blood donation (p < 0.001). The baseline IVC-CI and IVCe did not correlate with the change in CO (p-values ≥ 0.40). The alterations in IVC-CI and IVCe induced by blood donation also did not correlate with the change in CO (p ≥ 0.71). The sensitivities of IVC-CI or IVCe, defined as an increase in IVC-CI and a decrease in IVCe, for picking up any decrease in CO were 81.3% and 84.4%, respectively. In the control group, no effect was seen between measurements.

Conclusion: IVC-CI and IVCe did not correlate with the magnitude of hemodynamic response to early hemorrhage. The sensitivity of serial IVC measurements was approximately 80% for detecting early blood loss.