Blood vs. Crystalloids
Holcomb JB, Donathan DP, Cotton BA, et al. Prehospital transfusion of plasma and red blood cells in trauma patients. Prehosp Emerg Care. June 16, 2014. [Epub ahead of print.]
For years, physicians and researchers have looked for ways to replace missing blood products with something that actually carries oxygen while expanding volume. Unfortunately, crystalloids only add volume while thinning out the existing clotting products. Carrying blood has seemed impractical—if not bulky and unstable—due to the risk of transfusion reactions.
Researchers from the University of Texas Health and Memorial Hermann in Houston, Texas, wanted to compare the morbidity and mortality of patients who received fluid versus patients who received packed red blood cells (PRBCs) and fresh frozen plasma (FFP) during prehospital care.
Methods: Trauma patients transported to Memorial Hermann from September 2011 to April 2013 by air and ground units were retrospectively reviewed. Life Flight, the air medical service of Memorial Hermann, carries thawed plasma and PRBCs to be given during transport. The blood products are kept at flight bases in a special refrigerator monitored remotely by the blood bank. All other studied services use standard colloid solutions such as normal saline for resuscitation. Non-burn trauma patients greater than 16 years old who arrived from a scene (not transferred) were included in the study criteria. Patients were sorted into two groups: Life Flight patients who were brought by the agency able to infuse blood products, and other air agency (OA) patients who received standard resuscitation methods. Study end points were early outcomes of resuscitation, overall survivability and wastage of blood products.
Data: A total of 1,667 patients were studied during the period. Life Flight patients given blood products accounted for 19% of patients (137), while the remaining 81% (1,530) underwent standard fluid resuscitation irrespective of the service transporting. The overwhelming majority of patients were males in their late 20s to early 50s in all groups.
There was no significant statistical difference between arrival vital signs in either group; however, patients who didn’t get blood products enroute were more likely to be acidotic. There was also no statistically significant decrease in 30-day mortality in unadjusted statistics.
Patients who received blood products were less likely to receive an abundance of fluid, with a median administration of 1 L compared to 1.5 L in the OA group. Patients who benefitted the most from blood product administration were those admitted directly to the floor or surgery; although this improvement was primarily noted in the six-hour mortality rate rather than the 24-hour or 30-day group.
Interestingly, only 1.9% (18) of the 942 units of blood products were wasted and unusable during the 20-month study period.
Discussion: As mentioned above, crystalloids are simply good for replacing volume and don’t carry oxygen or clotting factors. In fact, research lately has pointed toward an increased mortality with over-aggressive fluid administration. The largest takeaway from this study is that blood products may be more viable in the out-of-hospital resuscitation environment than we previously thought. At 1.9%, waste is quite low, and there were no documented adverse reactions in the blood group.
Can we attribute the administration of blood as a definite reducer of mortality? Probably not. The data points are too small; however, this study is a stepping point toward more research in the prehospital use of blood, specifically with air services that may have more controls available, with the blood at a fixed hangar, rather than traveling in an ambulance throughout the day.
There’s something to be said for the relatively level mortality rate in both groups. This may just be a case of people who’ll die from their injuries regardless of anything done in the field. Because the research of blood is currently limited to the battlefield, maybe it’s time for us to start trialing blood in the civilian EMS setting. If you do, please, document your results and send them to us at the email addresses in our bios below.
What we know: Colloid solutions don’t offer the same benefits as blood in the resuscitation of trauma or acute hemorrhage patients, but the use of blood in the prehospital environment is understudied.
What these studies add: Blood may be a viable option in the prehospital setting. With a low waste rate and a strict protocol, blood may soon be available to EMS agencies worldwide.
Life Flight has a standing protocol for the administration of blood products for patients in the field. Patients over 12 years old who meet two of the four following criteria may have blood administered in the field through a warming infusion system:
1. Penetrating trauma to the chest;
2. Systolic blood pressure less than 90;
3. Heart rate greater than 120 bpm; or
4. A positive abdominal focused assessment with sonography in trauma exam, performed with ultrasound.
Each patient receives one unit of plasma followed by one unit of PRBCs. Resuscitation may continue until adequate, including repeat administration of plasma and PRBCs in a 1:1 method.