Background: The aim of this study was to validate a calculation of pulse rate (PR) divided by pulse pressure (pulse rate over pressure evaluation [ROPE] index) as a method of predicting early hemorrhagic compensation in healthy patients donating blood. The ROPE index calculations were compared with shock index (PR divided by systolic blood pressure) calculations for the same donors.
Methods: This was a prospective serial observational study where blood donors received blood pressure and PR recordings immediately before and after donating 1 unit (470 mL) of blood over 20 minutes while in the supine position. ROPE and shock indices were calculated for each recording. The indices calculated before and after blood loss were analyzed to determine whether there was a significant change.
Results: One hundred sixteen donors were assessed; 78% and 73% experienced a significant decrease in systolic blood pressure and pulse pressure, respectively. There was no significant change in PR. Both the mean ROPE and shock indices increased significantly by 12.2% (p < 0.0001) and 6.9% (p < 0.0001), respectively. The ROPE index correlated well with the shock index in donors, both before and after blood loss (Pearson's correlation coefficients of 0.80 and 0.79, respectively). Changes in both indices had a similar but looser correlation (Pearson's correlation coefficient of 0.60).
Conclusion: Loss of 1 unit of blood in adult donor causes a significant increase in a blood donor's ROPE and shock indices. This supports previous research which suggests that changes in the ROPE index have the potential to be an early indicator of blood loss.
Level of evidence: Prognostic study, level II.