Alloimmunization and pregnancy risk

Show Notes

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What is prehospital blood transfusion

• Administration of blood products in the field prior to hospital arrival

• Aimed at patients in hemorrhagic shock

Why this matters

• Traditional US prehospital resuscitation relied on crystalloid

• ED and trauma care now prioritize early blood

• Hemorrhage occurs before hospital arrival

• Delays to definitive hemorrhage control are common

• Earlier blood may improve survival

Supporting rationale

• ATLS and trauma paradigms emphasize blood over fluid

• National organizations support prehospital blood when feasible

• EMS already manages high risk, time sensitive interventions

Evidence overview

• Data are mixed and evolving

  • COMBAT: no benefit

  • PAMPer: mortality benefit

  • RePHILL: no clear benefit

• Signal toward benefit when transport time exceeds ~20 minutes

• Urban systems still experience long delays due to traffic and geography

• LA County median time to in hospital transfusion ~35 minutes

LA County program

• ~2 years of planning before launch

• Pilot began April 1

• Partnerships:

  • LA County Fire

  • Compton Fire

  • Local trauma centers

  • San Diego Blood Bank

• 14 units of blood circulating in the field

• Blood rotated back 14 days before expiration

• Ultimately used at Harbor UCLA

• Continuous temperature and safety monitoring

Indications used in LA County

• Focused rollout

• Trauma related hemorrhagic shock

• Postpartum hemorrhage

Physiologic criteria:

• SBP < 70

• Or HR > 110 with SBP < 90

• Shock index ≥ 1.2

• Witnessed traumatic cardiac arrest

Products:

• One unit whole blood preferred

• Two units PRBCs if whole blood unavailable

Early experience

• ~28 patients transfused at time of discussion

• Evaluating:

  • Indications

  • Protocol adherence

  • Time to transfusion

  • Early outcomes

• Too early for outcome conclusions

California collaboration

• Multiple active programs:

  • Riverside (Corona Fire)

  • LA County

  • Ventura County

• Additional programs planned:

  • Sacramento

  • San Bernardino

• Programs meet monthly as CalDROP

• Focus on shared learning and operational optimization

Barriers and concerns

• Trauma surgeon concerns about blood supply

• Need for system wide buy in

• Community engagement

• Patients who may decline transfusion

• Women of childbearing age and alloimmunization risk

• Risk of HDFN is extremely low

• Clear communication with receiving hospitals is essential

Future direction

• Rapid national expansion expected

• Greatest benefit likely where transport delays exist

• Prehospital Blood Transfusion Coalition active nationally

• Major unresolved issue: reimbursement

• Currently funded largely by fire departments

• Sustainability depends on policy and payment reform

Take-Home Points

• Hemorrhagic shock is best treated with blood, not crystalloid

• Prehospital transfusion may benefit patients with prolonged transport times

• Implementation requires strong partnerships with blood banks and trauma centers

• Early data are promising, but patient selection remains critical

• National collaboration is key to sustainability and future growth