Pre-hospital pulse pressure as an early predictor of active hemorrhage in trauma patients

Early identification of active hemorrhage (AH) is a critical challenge in trauma care. Narrowed pulse pressure (PP) has been associated with AH at the time of emergency department arrival; however, its role in the prehospital setting remains unclear. The aim of this study was to evaluate the utility of prehospital PP as an early predictor of AH in trauma.

We conducted a retrospective multi-centre study (January 2017 - January 2020) including adult trauma patients at all three level 1 trauma centers in Alberta, Canada. AH was defined as either operative or interventional radiology hemorrhage control within 24 h of arrival, or transfusion of ≥ 4 units of packed red blood cells within 4 h. ROC and multivariable logistic regression analyses were used to characterize associations between prehospital PP and AH.

2177 patients met inclusion criteria, of whom 68 (3%) had active hemorrhage. Compared to non-bleeding patients, AH patients had significantly narrower median prehospital PP (40 mmHg, IQR 29-52 vs 53, IQR 42-67; p < 0.001) and lower median systolic blood pressure (SBP; 111 mmHg, IQR 101-136 vs 138, IQR 122-156; p < 0.001). Prehospital PP demonstrated moderate ability to predict hemorrhage (AUC 0.73, 95% CI 0.67-0.79), comparable to SBP (AUC 0.74, 95% CI 0.67-0.81). Narrowed prehospital PP was independently associated with AH (odds ratio 1.51, 95% CI 1.28-1.79), reflecting a 51% increase in the risk of hemorrhage for each 10 mmHg the PP narrowed. Compared to non-bleeding patients, AH patients had worse outcomes including increased risk of ICU admission (63% vs 18%; p < 0.001), prolonged hospital length of stay (22 days, IQR 8-53 vs 7 days, IQR 4-15; p < 0.001), and increased mortality, although this did not reach statistical significance (18% vs 10%; p = 0.068).

Prehospital PP ≤ 45 mmHg identifies patients at risk for active hemorrhage and given its high negative predictive value, is most useful to rule-out patients without active hemorrhage in the prehospital setting. PP is a useful adjunct to support early recognition of hemorrhage in trauma. This is particularly relevant for trauma centres serving large geographic regions, where prolonged transport times delay definitive hemorrhage control. Its incorporation into the prehospital assessment has potential to help facilitate timely mobilization of hemorrhage control resources that actively bleeding patients require.