System Report: The San Antonio Fire Department Blood Delivery Program

This article appeared in the EMS World special supplement Combating the Hidden Dangers of Shock in Trauma, developed by Cambridge Consulting Group and sponsored by North American Rescue, LifeFlow by 410 Medical, and QinFlow. Download the supplement here. 

The San Antonio Fire Department (SAFD) is the sole 9-1-1 EMS provider for a population of more than 1.5 million people in an area encompassing 468 square miles. Department medical direction is provided by the Office of the Medical Director (OMD) through the University of Texas (UT) Health San Antonio School of Health Professions. 

The SAFD began prehospital low-titer O-positive whole blood (LTOWB+) transfusions on October 1, 2018. It carries single units (approximately 520 ml) of LTOWB+ on EMS physician response vehicles, EMS medical officer (MOF) supervisor vehicles, and medical special operations unit mobile intensive care ambulances. Every day there are 8 units of LTOWB+ available for qualifying patients (see Figure 1). When the EMS physician is on shift, they also carry a unit, providing for 9 in the system. 

Daily Operations and MCIs

All SAFD paramedic dispatchers alert blood-carrying vehicles for calls with a high probability of requiring prehospital blood transfusions. The dispatch algorithm, developed by the OMD and SAFD, allows paramedic discretion when dispatching prehospital whole blood units for patients in hemorrhagic shock.

Approximately 76% of calls that result in EMS blood transfusions are the result of traumatic injury. The trauma calls with the highest percentage of blood transfusions are those involving shootings. Cuttings and complex motor vehicle collisions are other major traumatic causes. The remaining 24% of transfusions are medical in nature, with gastrointestinal hemorrhage and obstetrical cases the leading causes. 

All field personnel have the option to request a blood-carrying apparatus on scene based on their patient assessment. Rendezvous en route to the hospital with a transporting unit that needs blood isn’t common, but it’s an authorized practice and has proved a valuable evolution.

In the event of a mass casualty incident (MCI), an MOF will drive to South Texas Blood and Tissue Center (STBTC) and gather up to 30 more units of LTOWB+. These units are then placed in a validated cold storage container and brought to the scene. The MOF is the perfect blood-delivery conduit for an MCI, as they are in a marked response vehicle and have real-time communications with those on scene.

Whole Blood Stewardship

There are many logistical challenges to overcome with a prehospital whole blood response program. Together the OMD, SAFD, and regional partners developed and deployed the following best practices regarding blood storage, transport, and transfusion with a focus on utilizing every LTOWB+ unit. 

SAFD EMS is issued a single unit of LTOWB+ from the blood center, and the blood is in the field for the first 14 days of its 35-day life cycle. If unused after 14 days, the blood is returned to the blood center and validated. Upon validation it is scheduled for immediate delivery to the regional trauma center, resulting in an extremely high utilization rate. Less than 1% of LTOWB+ is lost in the entire system.

A recent Association for the Advancement of Blood & Biotherapies (AABB) standard for prehospital blood practice states blood must be kept at 1–10°C (33.8–50°F) during transport and 1–6°C (33.8–42.8°F) for storage. SAFD maintains its whole blood temperature throughout its 14-day life cycle with a unique cold-storage program. During the medics’ 24-hour shift, they use a validated Crēdo cooler manufactured by Peli BioThermal to keep blood at the appropriate temperature. The blood is kept on the vehicle in a chilled cooler for the duration of the shift (see Figure 2). 

Another Crēdo cooler without any contents is kept in a freezer at 0°C (32°F) for 24 hours until shift trade the next day. At shift trade the SAFD medics remove the empty cooler from the freezer. They remove the blood from the cooler that has been on the blood-carrying vehicle for 24 hours and place it in the cooler just removed from freezer. They then place the newly empty cooler into the freezer. This process occurs every 24 hours for all LTOWB+ units.

A validation test on the Crēdo cooler was performed by the cooler manufacturer by exposing the cooler to ambient heat for 48 hours to keep the cooler’s internal blood storage space at an appropriate temperature.  

The STBTC conducted temperature validation on the Crēdo cooler for 8 hours at 70°C (158°F) to make sure that internal cooler temperatures could handle South Texas summer days. Internal quality improvement data shows all 8 units of blood carried by SAFD are kept at an average of 5.1°C (41.18°F). 

Prehospital LTOWB+ is warmed to body temperature using the QinFlow Warrior portable blood and fluid warmer and rapidly transfused by SAFD medics for those in hemorrhagic shock. The QinFlow warmer can warm cold blood to 38°C (100.4°F) at 200 ml/min within 7 seconds of activation.

SAFD also uses an inline pump chamber that holds 30 ml and is squeezed by the medic to facilitate an increased flow rate. A newly developed tool to increase transfusion flow rates is wide-diameter tubing from Codan. This product was designed by specialists from the SAFD, OMD, and US military. Real-life performance and a recent study show SAFD can transfuse 520 ml of LTOWB+ at body temperature in approximately 4 minutes. 

The return of unused blood product is common in the blood-production industry. The San Antonio and South Texas prehospital blood rotation system reflects an extension of this same philosophy. 

If the LTOWB+ is not transfused in the field and remains compliant with cold chain custody, it’s returned to STBTC, the local supplier. Specialists there visually inspect the unit and complete a validation process that includes checking the Safe-T-Vue 10 blood temperature indicator attached to the blood and a temperature check with a validated handheld thermometer. After validation the blood is reissued to a rotation center—in this case University Hospital in San Antonio. If SAFD EMS performs a blood transfusion, or in the rare case a blood unit has any issue with cold chain custody, the department is financially responsible for the cost of that blood.

The SAFD uses 68% of the blood it obtains from STBTC during the 14-day transport, with the remaining 32% being returned. The busiest blood-carrying unit in the SAFD transfuses about 86% of its blood within the 14-day window. To date the San Antonio Fire Department has a 97.7% efficacy rate at keeping LTOWB+ from being wasted.

The blood rotation system allows for financial efficiency and resource stewardship. Currently financial reimbursement for prehospital blood transfusions is very limited, so the rotation process allows SAFD to dramatically limit expenses. The trauma center is substantially likely to utilize LTOWB+ as part of an enhanced resuscitation strategy; as a result its leaders are staunch supporters of the entire system of care, from the point of injury until arrival at definitive care, thereby making prehospital delivery of LTOWB+ feasible.

Medical Practice

Prehospital transfusion triggers were determined by the OMD after reviewing massive blood transfusion protocols, as well as prehospital and hospital transfusion studies. Analyzing this data showed there were no transfusion triggers that addressed the unique needs of a metropolitan EMS system.

Results from 2 recent trials of prehospital plasma transfusion revealed mortality ranging from approximately 10%–33% in their control arms.^1,2 However, previous data suggest clinically significant hypoperfusion may occur before a patient’s systolic blood pressure reaches 90 mmHg.^3–7 

We included EtCO₂ <25 mmHg in our criteria to identify these patients. Due to its relationship with pulmonary blood flow and cardiac output, EtCO₂ falls during shock states.^8–10 The relationship between abnormally low EtCO₂ and trauma patient outcomes is present in numerous studies from prehospital, ED, and operating room settings.^11–19

SAFD EMS will also transfuse LTOWB+ to select patients in cardiac arrest due to traumatic and nontraumatic hemorrhagic shock. The use of LTOWB+ in these situations is considered on a case-by-case basis per a standing order.

The following indications were developed by the UT Health San Antonio OMD to address prehospital patient care based on 1) understanding of transfusion research and 2) the diagnostic capabilities possessed by SAFD to assess patients for blood transfusion.

Indications for Transfusion of LTOWB+

• Hemorrhagic shock in traumatic and medical patients with any of the following:
  • SBP <70 mmHg 
  • SBP <90 with heart rate (HR) ≥110 bpm
  • EtCO₂ <25 mmHg
  • Witnessed arrest from hemorrhage or suspected hemorrhage <5 mins prior to provider arrival and continuous CPR throughout downtime
  • Age ≥65 y and SBP ≤100 mmHg with HR ≥100 bpm

Contraindications for Transfusion of LTOWB+

• Religious objection to human blood products

Relative Contraindications for Transfusion of LTOWB+

• Patients less than 6 years old require consultation with EMS medical direction to determine eligibility for whole blood transfusion and assist with the precise management of infusion parameters. SAFD units are supplied with a burette set for use on indicated pediatric patients to achieve precision in LTOWB+ transfusion. This relative contraindication is based upon safety. A large single bolus of the full volume of the bag (520 mL) may have a negative impact on a child less than 6 years. 

Limitations

There may be factors that require customization to make the SAFD system generalizable to other jurisdictions and regions. As a delegated-practice state, Texas provides the EMS medical director with the authority to utilize LTOWB+ in the prehospital environment. 

Some states have scope-of-practice laws that may limit the initiation of LTOWB+ or blood products by paramedics. Many regions have successfully lobbied for ground ambulances to carry blood. Some form of prehospital blood transfusion program presently exists in several states, with more than a dozen others working to establish programs. If a state or region lacks a robust trauma system infrastructure, this program may prove challenging to replicate.

Program Results

The SAFD LTOWB+ blood transfusion program has transfused more than 900 units of whole blood in a little over 4½ years.

Multiple articles have been written discussing the program and patients. Two recent journal articles describe the development of the whole blood program.^20,21 Another discusses the epidemiological and financial considerations of a prehospital whole blood program.²²

Two separate case studies have been written and evaluate prehospital blood transfusions received by females of childbearing age. The first discussed an obstetrical case involving an unresponsive pregnant female who received blood and had vital signs and mental status improvement on arrival to the hospital, where she received an emergent cesarean section.²³ The mother and baby both survived and were discharged from hospital within a few weeks.

The second case involved a young mother involved in an MVC.²² The patient arrested while entrapped in the vehicle. She was intubated, had CPR performed, was given a unit of LTOWB+, and regained pulses in the field. She received another unit of whole blood en route to the hospital by air EMS. In the hospital it was determined the patient had a splenic laceration, and she had angioembolization performed. She’s alive and well and has been a positive force in the community by speaking about the benefits of whole blood and hosting blood drives. 

A recent retrospective review showed prehospital blood reduces early mortality in severely injured trauma patients.²4 A retrospective review abstract of prehospital whole blood administration in critically ill gastrointestinal bleeding patients showed a significant improvement in shock index.²⁵

A large retrospective review is ongoing and will look at 3 years of blood transfusion data for SAFD. Early results are underpowered and not statistically significant, at P<0.07, but trend toward doubling 30-day survival for trauma patients.

Conclusion

The standard of care in the hospital is to transfuse blood for those in hemorrhagic shock. One of the tenets of the OMD in San Antonio is to bring lifesaving hospital care to the prehospital patient. This concept has taken place for many years in all EMS systems. At one point in medical history, defibrillation was a physician skill, paramedics didn’t do ECGs, EMTs didn’t place supraglottic airways, and lay people didn’t administer naloxone or epinephrine.

Those days are over. Many skills and procedures that were once the purview of the hospital and physicians are now performed by the prehospital healthcare provider and even the lay person. Early data suggests the hospital standard of care, transfusing hemorrhagic shock patients with blood, should be brought to prehospital patients. The SAFD is doing just that.

References

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(4): 315–26.

2. Moore HB, Moore EE, Chapman MP, et al. Plasma-first resuscitation to treat haemorrhagic shock during emergency ground transportation in an urban area: A randomised trial. Lancet. 2018; 392(10144): 283–291.

3. Eastridge BJ, Salinas J, Wade CE, Blackbourne LH. Hypotension is 100 mm Hg on the battlefield. Am J Surg. 2011; 202(4): 404–8.

4. Oyetunji TA, Chang DC, Crompton JG, et al. Redefining hypotension in the elderly: Normotension is not reassuring. Arch Surg. 2011; 146(7): 865–9.

5. Hasler RM, Nuesch E, Juni P, et al. Systolic blood pressure below 110 mmHg is associated with increased mortality in penetrating major trauma patients: Multicentre cohort study. Resuscitation. 2012; 83(4): 476–81.

6. Hasler RM, Nuesch E, Juni P, et al. Systolic blood pressure below 110 mm Hg is associated with increased mortality in blunt major trauma patients: multicentre cohort study. Resuscitation. 2011; 82(9): 1202–7.

7. Eastridge BJ, Salinas J, McManus JG, et al. Hypotension begins at 110 mm Hg: Redefining “hypotension” with data. J Trauma. 2007; 63(2): 291–7; discussion 7–9

8. Shibutani K, Muraoka M, Shirasaki S, et al. Do changes in end-tidal PCO2 quantitatively reflect changes in cardiac output? Anesth Analg. 1994; 79(5): 829–33.

9. West JB. State of the art: Ventilation-perfusion relationships. Am Rev Respir Dis. 1977; 116(5): 919–43.

10. Trillo G, von Planta M, Kette F. ETCO2 monitoring during low flow states: Clinical aims and limits. Resuscitation. 1994; 27(1): 1–8.

11. Williams DJ, Guirgis FW, Morrissey TK, et al. End-tidal carbon dioxide and occult injury in trauma patients: ETCO2 does not rule out severe injury. Am J Emerg Med. 2016; 34(11): 2146–9.

12. Dunham CM, Chirichella TJ, Gruber BS, et al. In emergently ventilated trauma patients, low end-tidal CO2 and low cardiac output are associated and correlate with hemodynamic instability, hemorrhage, abnormal pupils, and death. BMC Anesthesiol. 2013; 13(1): 20.

13. Caputo ND, Fraser RM, Paliga A, et al. Nasal cannula end-tidal CO₂ correlates with serum lactate levels and odds of operative intervention in penetrating trauma patients: A prospective cohort study. J Trauma Acute Care Surg. 2012; 73(5): 1202–7.

14. Tyburski JG, Carlin AM, Harvey EH, et al. End-tidal CO₂-arterial CO₂ differences: A useful intraoperative mortality marker in trauma surgery. J Trauma. 2003; 55(5): 892–7.

15. Tyburski JG, Collinge JD, Wilson RF, Carlin AM, Albaran RG, Steffes CP. End-tidal CO₂-derived values during emergency trauma surgery correlated with outcome: A prospective study. J Trauma. 2002; 53(4): 738–43.

16. Dudaryk R, Bodzin DK, Ray JJ, et al. Low end-tidal carbon dioxide at the onset of emergent trauma surgery is associated with nonsurvival: A case series. Anesth Analg. 2017; 125(4): 1261–6.

17. Stone ME, Jr., Kalata S, Liveris A, et al. End-tidal CO₂ on admission is associated with hemorrhagic shock and predicts the need for massive transfusion as defined by the critical administration threshold: A pilot study. Injury. 2017; 48(1): 51–7.

18. Childress K, Arnold K, Hunter C, et al. Prehospital end-tidal carbon dioxide predicts mortality in trauma patients. Prehosp Emerg Care. 2018; 22(2): 170–4.

19. Deakin CD, Sado DM, Coats TJ, et al. Prehospital end-tidal carbon dioxide concentration and outcome in major trauma. J Trauma. 2004; 57(1): 65–8.

20. Zhu CS, Pokorny DM, Eastridge BJ, et al. Give the trauma patient what they bleed, when and where they need it: Establishing a comprehensive regional system of resuscitation based on patient need utilizing cold-stored, low-titer O+ whole blood. Transfusion. 2019; 59(S2): 1429–38.

21. Weymouth W, Long B, Koyfman A, et al. Whole blood in trauma: A review for emergency clinicians. J Emerg Med. 2019; 56(5): 491–8.

22. Mapp JG, Manifold CA, Garcia AM, et al. Prehospital blunt traumatic arrest resuscitation augmented by whole blood: A case report. Transfusion. 2020; 60(5): 1104–7.

23. Newberry R, Winckler CJ, Luellwitz R, et al. Prehospital transfusion of low-titer O + whole blood for severe maternal hemorrhage: A case report. Prehosp Emerg Care. 2020; 24(4): 566–75.

24. Braverman MA, Smith A, Pokorny D, et al. Prehospital whole blood reduces early mortality in patients with hemorrhagic shock. Transfusion. 2021; 61(Suppl 1): S15–S21.

25. Wentling J, Wampler D, Everitt B, et al.  Prehospital Low Titer O + Whole Blood Administration for Gastrointestinal Hemorrhage: Effect on Shock Index and Vital Signs. Research Abstracts for the 2022 NAEMSP Annual Meeting. Prehosp Emerg Care. 2022; 26(1): 108–63.

CJ Winckler, MD, serves as the deputy medical director for the San Antonio Fire Department and is an associate clinical professor at UT Health San Antonio in both the Department of Emergency Health Sciences and the Department of Emergency Medicine.

David Miramontes, MD, is the medical director for the San Antonio Fire Department and an associate clinical professor at UT Health San Antonio in the Department of Emergency Health Sciences. He was previously EMS medical director and assistant fire chief for the District of Columbia (DC) Fire and EMS Department and Toledo Fire Department and metro agencies in northwest Ohio.

William Bullock, EMT-P, is a 21-year veteran of the San Antonio Fire Department and currently a lieutenant and EMS field supervisor. He’s functioned as a lead team member of the SAFD blood program since the program’s inception in 2018.