Objective: The aim of this study was to determine the hemodynamic response and calculated shock index (SI=heart rate [HR]/systolic blood pressure [SBP]) in early acute blood loss.
Methods: This was a prospective observational study that enrolled healthy blood donors. Patients were excluded if not eligible for blood donation. Baseline vital signs were obtained, 450 mL of blood was removed over 20 minutes, and vital signs were repeated immediately postdonation while lying and after 1 and 5 minutes of standing. Difference was tested using a paired t test with P<.01 set for significance.
Results: Forty-six patients were enrolled; means for each time interval are shown below with 95% confidence intervals.
Conclusions: A significant elevation in mean SI was observed in healthy volunteers after standing for 1 and 5 minutes. Although significant changes in HR and SBP were observed, these indices were still within "normal" limits. The SI may be more useful in early hemorrhage than either the HR or SBP alone.