52 in 52 – #29: The “PAMPer” Study

Welcome back to the “52 in 52” series. This collection of posts features recently published must-know articles. This week the series covers prehospital transfusion of plasma.

Author: Christiaan van Nispen, MD (Emergency Medicine Physician Resident, San Antonio, TX) and Brannon Inman (Chief Resident, Emergency Medicine Physician, San Antonio, TX) // Reviewed by: Alex Koyfman, MD (@EMHighAK); Brit Long, MD (@long_brit)

Prehospital Plasma during Air Medical Transport in Trauma Patients at Risk for Hemorrhagic Shock

AKA: The “PAMPer” Study

Clinical question:

In patients at risk for hemorrhagic shock, is there a mortality benefit to pre-hospital transfusion of plasma as the initial resuscitation fluid compared to the standard of care?


Study design:

  • Multi-centered, cluster-randomization trial




  • Inclusion:
    • Patients being transported by one of 27 participating air transportation teams from the scene of blunt or penetrating injury or from a referring ED to one of 9 participating trauma centers
    • At risk for hemorrhagic shock during transport or prior to arrival of transport team, defined as at least one episode of either:
      • Systolic blood pressure < 90 mm Hg AND heart rate > 108 beats per minute
      • Systolic blood pressure < 70 mm Hg irrespective of heart rate
    • Assumed consent for participation in trial unless patient or family voiced opposition; patients could opt out of continued participation later
  • Exclusion:
    • Younger than 18 years or older than 90 years
    • Inability to establish intravenous and/or intraosseous access
    • Isolated fall from standing mechanism of injury
    • Isolated drowning mechanism of injury
    • Isolated hanging mechanism of injury
    • Presence of greater than 20% total body surface area burns
    • Traumatic cardiac arrest lasting longer than 5 minutes
    • Penetrating brain injury
    • Incarcerated patients
    • Pregnant patients



  • Infusion of 2 units of universal donor or group A low titer B (<1:100) thawed plasma to patients at risk for hemorrhagic shock in addition to standard of care
  • Plasma was the initial resuscitative fluid prior to advancing to the erstwhile standard of care for fluid resuscitation.



  • Standard of care only with a goal of systolic blood pressure ≥ 90 mm Hg
  • Standard of care varied by air transportation team.
    • 13 of 27 air transportation teams also carried 2 units of universal donor packed red blood cells (pRBCs) which could be infused after a liter of crystalloid if one of the following conditions were present:
      • Systolic blood pressure < 90 mm Hg
      • Heart rate > 120 beats per minute
      • Deteriorating mental status
      • Capillary refill > 2 seconds
    • Remainder of teams used isotonic crystalloid infusion only.


Enrollment and Randomization:

  • Initially calculated that 530 screened prehospital patients would lead to 504 eligible patients, which would provide 88% power to detect a 14% difference.
  • 2 years, 8 months into the trial, enrollment was increased to 564 to account for higher-than-expected ineligible patients.
  • Intervention and Comparator arms were demographically well balanced.
  • Enrolled patients were largely men (72.7%), sustained injuries from blunt trauma (82.4%), and appeared at high risk for severe outcomes, given the median prehospital heart rates, systolic blood pressures, and rates of intubation reported.
  • 390 enrolled at scene; 111 enrolled from referring ED.
  • Due to limited shelf life of thawed plasma, randomization was clustered by air medical team base.
    • Each month, each base was randomized to carry or not to carry plasma in addition to their standard of care.
  • Primary outcome data was available for 96% of patients.


  • Statistically significant difference in primary outcome of 30-day mortality
    • 53 deaths in the plasma group
    • 89 deaths in standard of care group
    • 2% vs. 33.0%; difference, −9.8 percentage points; 95% confidence interval, −18.6 to −1.0%; P=0.03
  • There remained a 39% lower risk of death at 30 days in the plasma group when accounting for variations in pre-hospital crystalloid volume infused, pre-hospital pRBC volume infused, and clustering at the base level
  • Statistically significant difference in initial prothrombin time, which was a secondary outcome
    • 1.2 in plasma group
    • 1.3 in control group
  • Other secondary outcomes lacked statistical significance:
    • 24-hour mortality
    • In-hospital mortality
    • Onset of acute lung injury/acute respiratory distress syndrome
    • Onset of multi-organ failure
    • Median total 24-hour volume of pRBCs transfusion
    • Median 24-hour volume of plasma transfusion
    • Median 24-hour volume of platelet transfusion
    • Vasopressor requirement in first 24 hours
    • Onset of nosocomial infection
    • Allergic reaction or transfusion related reaction
    • Median initial results of thromboelastography

Take aways:

  • Positive trial: pre-hospital plasma appears superior to standard of care alone.
  • Intervention group was less likely to be administered prehospital pRBCs (26.1% vs. 42.1%) and received lower median crystalloid volume (500mL vs. 900mL) yet had better 30-day mortality outcomes.
  • Effect was larger in the patients transported from scene compared to patients transported from a referring ED, suggesting that earlier plasma transfusion might be better, though more research is necessary for validation.
  • Though statistically significant, it is unlikely that the 0.1 difference in initial prothrombin time is physiologically or clinically meaningful enough to account for the apparent mortality benefit.
  • The study is appropriately powered and has limited loss to follow-up.

My take:

  • In patients with pre-hospital signs of hemorrhagic shock, pre-hospital plasma transfusion in conjunction with pRBCs and/or crystalloid appears superior to pRBCs and/or crystalloid alone, which tracks with other recent data demonstrating that balanced transfusion and the avoidance of crystalloid are best practices.
  • More research is needed to validate the results of this trial, with better standardized local protocols regarding the transfusion of other blood products and crystalloid.



  1. Sperry JL, Guyette FX, Brown JB, et al. Prehospital Plasma during Air Medical Transport in Trauma Patients at Risk for Hemorrhagic Shock. N Engl J Med.2018; 379(18):1783. DOI 10.1056/NEJMc1811315


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