Understanding pre-hospital blood transfusion decision-making for injured patients: an interview study

Blood Product Administration in the Prehospital Setting: A Scoping Review

OBJECTIVES

Implementing prehospital blood products for treating hemorrhagic shock has been utilized globally in military and civilian settings. This review aims to compare various guidelines for using blood products, including the types of blood products, injuries, biomarkers (hemodynamic measurement) to indicate use, associated treatments and risks, and the logistical concerns of storage and wastage in the prehospital setting. Furthermore, it explores whether prehospital blood transfusions are beneficial and a safe treatment option.

METHODS

Data were collected using a systematic search and screening process of online databases CINAHL, Medline, and Scopus, as well as by creating a PRISMA flow diagram to screen articles using inclusion and exclusion criteria. Forty-five articles were screened, with twenty-five excluded, resulting in twenty articles in this scoping review.

RESULTS

The most frequently used blood product used was red blood cells, with twelve studies using either red blood cells alone or in combination with other products. Indications for blood use varied across services, but all aimed to address hemodynamic instability as a primary indication for blood transfusion. Eleven studies recorded no adverse reactions. Only one study reported chills and shivers; however, it was unclear if blood products were the cause. Nine studies avoided logistical issues of storage and wastage to create a feasible rotation system.

CONCLUSIONS

Prehospital blood was used in medical, trauma, and maternity-related hemorrhage. Many types of blood products are in use, ranging from component therapy to whole blood, with each protocol having different indications of use and treatment guidelines aimed at improving hemodynamic stability.

How Much Does Intravenous Fluid Cause Hematocrit to Drop? Improving Interpretation of Hematocrit Toward Better Post-Hemorrhage Care

INTRODUCTION

Hemorrhage is assessed, at least in part, via hematocrit testing. To differentiate unexpected drops in hematocrit because of ongoing hemorrhage versus expected drops as a result of known hemorrhage and intravenous fluid administration, we model expected post-operative hematocrit values accounting for fluid balance and intraoperative estimated blood loss (EBL) among patients without substantial post-operative bleeding.

MATERIALS AND METHODS

We reviewed patient-level data from the electronic health record of an academic medical center for all non-pregnant adults admitted for elective knee or hip arthroplasty from November 2013 to September 2022 who did not require blood products. We used linear regression to evaluate the association between post-operative hematocrit and predictor variables including pre-operative hematocrit, intraoperative net fluid intake, blood volume, time from surgery to lab testing, EBL, patient height, and patient weight.

RESULTS

We included 6,648 cases. Mean (SD) estimated blood volume was 4,804 mL (1023), mean net fluid intake was 1,121 mL (792), and mean EBL was 144 mL (194). Each 100 mL of EBL and 1,000 mL net positive fluid intake was associated with a decrease of 0.52 units (95% CI, 0.51-0.53) and 2.4 units (2.2-2.7) in post-operative hematocrit. Pre-operative hematocrit was the strongest predictor of post-operative hematocrit. Each 1-unit increase in pre-operative hematocrit was associated with a 0.70-unit increase (95% CI, 0.67-0.73) in post-operative hematocrit. Our estimates were robust to sensitivity analyses, and all variables included in the model were statistically significant with P <.005.

CONCLUSION

Patient-specific data, including fluid received since the time of initial hemorrhage, can aid in estimating expected post-hemorrhage hematocrit values, and thus in assessing for the ongoing hemorrhage.

Identification of major hemorrhage in trauma patients in the prehospital setting: diagnostic accuracy and impact on outcome

Background

Hemorrhage is the most common cause of potentially preventable death after injury. Early identification of patients with major hemorrhage (MH) is important as treatments are time-critical. However, diagnosis can be difficult, even for expert clinicians. This study aimed to determine how accurate clinicians are at identifying patients with MH in the prehospital setting. A second aim was to analyze factors associated with missed and overdiagnosis of MH, and the impact on mortality.

Methods

Retrospective evaluation of consecutive adult (≥16 years) patients injured in 2019-2020, assessed by expert trauma clinicians in a mature prehospital trauma system, and admitted to a major trauma center (MTC). Clinicians decided to activate the major hemorrhage protocol (MHPA) or not. This decision was compared with whether patients had MH in hospital, defined as the critical admission threshold (CAT+): administration of ≥3 U of red blood cells during any 60-minute period within 24 hours of injury. Multivariate logistical regression analyses were used to analyze factors associated with diagnostic accuracy and mortality.

Results

Of the 947 patients included in this study, 138 (14.6%) had MH. MH was correctly diagnosed in 97 of 138 patients (sensitivity 70%) and correctly excluded in 764 of 809 patients (specificity 94%). Factors associated with missed diagnosis were penetrating mechanism (OR 2.4, 95% CI 1.2 to 4.7) and major abdominal injury (OR 4.0; 95% CI 1.7 to 8.7). Factors associated with overdiagnosis were hypotension (OR 0.99; 95% CI 0.98 to 0.99), polytrauma (OR 1.3, 95% CI 1.1 to 1.6), and diagnostic uncertainty (OR 3.7, 95% CI 1.8 to 7.3). When MH was missed in the prehospital setting, the risk of mortality increased threefold, despite being admitted to an MTC.

Conclusion

Clinical assessment has only a moderate ability to identify MH in the prehospital setting. A missed diagnosis of MH increased the odds of mortality threefold. Understanding the limitations of clinical assessment and developing solutions to aid identification of MH are warranted.

Level of evidence

Level III-Retrospective study with up to two negative criteria.

Study type

Original research; diagnostic accuracy study.