A descriptive retrospective analysis was performed on the patient records of all the patients receiving PHBT (pRBCs, freeze-dried plasma (FDP, LyoPlas AB, Deutsches Rotes Kreutz Blutspendedienst, Germany), or both) in Päijät-Häme EMS, Finland, from September 1, 2016, to December 31, 2020 (= 52 months).
The Päijät-Häme central hospital district administers prehospital EMS for 230,000 people living in the Päijät-Häme region in Southern Finland. The Päijät-Häme Central Hospital is the second-largest central hospital in Finland and most patients in need of acute care (including intensive care) can be treated locally, but some of the critical patient care (large burns or massive head injuries) is centralized into the five university hospitals. Patients suspected of needing more specialized care can be transported from the scene straight to the university hospital.
The region’s prehospital EMS responses approximately 42,000 emergency calls, 3,500 hospital transports, and 1,500 other medical support tasks yearly. A doctor-based rapid response unit, staffed with an advanced level paramedic (with at least Bachelor’s degree in prehospital nursing) and a prehospital emergency care (PHEC) physician, is on call every day from 8 am to 8 pm. The dispatch of the rapid response PHEC physician unit is based on predefined criteria or upon request of an ambulance crew. During night hours (from 8 pm to 8 am), prehospital blood product transfusions are initiated by an EMS field supervisor after consultation with a university hospital-based HEMS physician.
Prehospital transfusion protocol
The PHBT unit, carried by the rapid response PHEC physician unit during the day and EMS field supervisor unit during the night, consist of two units of type O RhD negative packed red blood cells and four units of freeze-dried plasma (FDP). The FDP in use is LyoPlas AB, Deutsches Rotes Kreutz Blutspendedienst, Germany. LyoPlas AB is made with AB-donors plasma and is compatible for all patients. The FDP is reconstructed with 200 ml of Aqua and equals 0.70–0.85 ml/ml of human plasma. Additionally, to the PHBT unit, three critical care ambulances in the area carry two units of freeze-dried plasma each and can start the blood product transfusion process before arrival of the red blood cells.
The guidelines for starting transfusion are similar in both trauma and non-traumatic patients: active major hemorrhage or suspicion of major hemorrhage with systolic blood pressure < 90 mmHg, or absent arterial radial pulse, or patient has symptoms of shock or when physician views that it would be beneficial for the patient. On arrival at the scene ambulance crew can suggest the PHBT for the rapid response unit physician or HEMS physician based on their clinical judgment.
In the PHBT protocol patient is transfused 1:1 with pRBCs and FDP. Before blood products patient is first given 1 g of tranexamic acid (TXA), second transfused with pRBCs and FDP and added to the protocol in the year 2020 calcium gluconate 10 mmol. The pRBCs are transfused through fluid warmer (MEQU M Warmer, MEQU Denmark) and the FDP is hung to gravity. Transfused amounts can variate, but for adults 1–2 units of pRBCs and 2–4 units of FDP are transfused. FDP can be transfused in suspected hemorrhage without pRBC transfusions with PHEC physicians’ decision.
The pRBCs can be changed or replenished any time of the day from the Päijät-Häme central hospital blood bank. The pRBCs are transported and stored in a temperature-controlled insulated box (Credo Promed, Pelican BioThermal, USA). The box has Seemoto censors for continuous temperature controlling (+ 2 °C to + 6 °C). Once a week pRBCs are replaced with new fresh units, and the previous units return to the blood bank, for circulation. All pRBC units are documented and tracked by the blood bank either transfused, waste, or back in stock. The rapid response unit crew prepares blood units for the transfusion and the ambulance crew prepares the patient for transfusion following their own checklists. All the area’s ambulances are equipped with a kit for blood drawing for ABO compatibility testing and the samples can be taken while inserting an intravenous line or it can be done separately.
Study subjects and data collection
All the patients that had PHBT during the study period (September 2016–December 2020) were identified and included in the study. Three pediatric patients (< 13 years) were identified among the study subjects and are also included in the analysis. The data used in this study was collected from Päijät-Häme region electronic prehospital database (Codea Leda), Päijät-Häme Central Hospital blood bank records, and the Päijät-Häme Central Hospital electronic patient records (LifeCare). All patients receiving blood components in a prehospital setting were identified and included. For 6 patients (9%), there were no recognizable timestamps on when the prehospital transfusion started and for 10 patients the blood pressure was not measurable before transfusion, or the time stamps did not correlate with the blood transfusion and were excluded from the hemodynamic variables analysis but were included in other parts.
The following data was retrieved form the electronic prehospital database: dispatch and transportation codes and timestamps for emergency call, arrival of the first ambulance crew to the scene, start of PHBT and arrival to the hospital, patient characteristics (age, gender), reason for hemorrhage (non-traumatic/traumatic), prehospital vital signs before transfusion, prehospital blood transfusion protocol (pRBC, FDP, TXA, Calcium gluconate) and markings of transfusion safety and transfusion related adverse reactions (any mentions of transfusion-related acute lung injury, transfusion-associated circulatory overload, allergic reactions, acute hemolysis or febrile non-hemolytic transfusion reactions). The hospital blood bank records were evaluated and all the used and wasted pRBC units were counted. The hospital’s electronic patient record was reviewed, and the following data was retrieved: patient vital signs on arrival, first blood laboratory results (pH, BE, Lactate, Ca-ion, Hb), in-hospital blood transfusions during the first 6 h and 24 h and outcomes (mortality during hospital care, transfer for other care facility or discharge to home).
All data was collected in a Microsoft Office Excel Spreadsheet (Microsoft Corporation) and data analysis was performed on SPSS (IBM, version 27) for Windows. The analysis started by describing the study population. Descriptive statistics include frequencies and percentages, and were counted for all categorical variables (gender, age, trauma/non-trauma groups, PHBT). The effects of PHBT on patient vital signs were analyzed. D'Agostino-Pearson Test was used to test the normal distribution of the continuous variables. Because most of the variables had skewed distribution, continuous variables were reported as median, and interquartile range (IQR) and further analyzed using Wilcoxon Signed rank test. A p-value less than 0.05 was considered significant. Delays of PHBT were analyzed and noted as median and interquartile range. PHBT safety was analyzed by noting any adverse events in prehospital and hospital records and analyzing possible fever reactions on patient temperature changes before and after PHBT. In hospital blood transfusions and outcomes of the hospital stay were analyzed and reported as frequencies and percentiles.