Pre-hospital Management in Trauma Patients: a Comparison Between Austria and Germany

Objectives To compare the pre-hospital treatment and intervention regimen for major trauma patients with comparable injury patterns between Austria (AUT) and Germany (GER). Patients and Methods This analysis is based on data retrieved from the TraumaRegister DGU ® . Data included severely injured trauma patients with an Injury Severity Score (ISS) ≥ 16, an age ≥ 16, and who were primary admitted to an Austrian (n=4.186) or German (n=41.670) Level I Trauma Center from 2008 to 2017. Endpoints included pre-hospital times and interventions performed until nal hospital admission. The analyzed data include patients’ demographics, mode of transportation, pre-hospital time management, hemodynamic stability, and various pre-hospital interventions. patients with ISS>16, c) for transport of rescue personnel to hard-to-reach regions or, d) for the transport of medicinal products. Further, the amount of administered uid in the pre-clinical setting should follow the concept of permissive hypotension/ hypotensive resuscitation, however the data are still inconclusive and mandate further research.


Introduction
Trauma registry comparisons are a feasible method for quality control, including the identi cation and detailed analysis of subgroups between countries [1]. They further allow to improve the quality of care [2][3][4], although international comparisons between trauma systems are still rare and lack a uni ed approach. Associating the pre-hospital, as well as the institutional performances between countries, underlies a careful patient-selection with adequate adjustments in case-mix and functional prediction models [5].
This study compares pre-hospital interventions performed in Austria (AUT) and Germany (GER) based on entries in the TraumaRegister DGU ® (TR-DGU), focusing on patients with multiple injuries. The advantage of this study is availability of data entries from AUT and GER into the common TR-DGU database, hence allowing for a direct data comparison.
Austria and Germany share a large border with similar emergency medical services (EMS) but alter in their geographic environments. Both countries rely on two different transportation systems in the care for trauma patients: Helicopter or ambulance transport with a physician. To the best of our knowledge, no prior evaluation comparing the Austrian and German pre-hospital trauma system has been conducted. Consequently, a comparative approach was chosen for this study aiming to determine differences in the pre-hospital management and to optimize treatment regimens.
Speci cally, this study addressed four questions:

TraumaRegister DGU ®
The TraumaRegister DGU ® is one of the largest registers of its kind worldwide and was founded in 1993.
The aim of this multi-center database is a pseudonymized and standardized documentation of severely injured patients. Data are collected prospectively in four consecutive time phases from the site of the accident until dis-charge from hospital: A) Pre-hospital phase, B) Emergency room and initial surgery, C) Intensive care unit and D) Discharge. Documentation includes detailed information on demographics, injury pattern, comorbidities, pre-and in-hospital management, course on intensive care unit, relevant laboratory ndings including data on transfusion, and outcome of each patient.
The infrastructure for documentation, data management, and data analysis is provided by AUC -Academy for Trauma Surgery (AUC -Akademie der Unfallchirurgie GmbH), a company a liated to the German Trauma Society. The scienti c leadership is provided by the Committee on Emergency Medicine, Intensive Care and Trauma Management (Sektion NIS) of the German Trauma Society. The participating hospitals submit their data pseudonymized into a central database via a web-based application.
Scienti c data ana-lysis is approved according to a peer review procedure de ned in the publication guideline of the TR-DGU.
The participating hospitals are primarily located in Germany (90%), but an increasing number of hospitals of other countries also contribute (i.e., Austria, Belgium, China, Finland, Luxembourg, Slovenia, Switzerland, The Netherlands, and the United Arab Emirates). Currently, approximately 30,000 cases per year from more than 650 hospitals are being entered into the database.
Participation in TR-DGU is voluntary. For hospitals associated with TR-DGU however, the entry of at least a basic data set is obligatory for reasons of quality assurance. Based on this data, statements about quality of care can be de ned and medical treatment methods examined for their effectiveness.
The present study is in line with the publication guidelines of the TraumaRegister DGU® and registered as TR-DGU project ID 2017-031.

Patients and Data acquisitions
This study is a retrospective analysis of trauma patients in AUT and GER, focusing on pre-hospital time, mode of transportation and interventions performed by physicians in the pre-hospital setting. All data were retrieved from the TraumaRegister DGU ® (TR-DGU). Patient data from the TR-DGU from 2008-2017 were analyzed. Data before 2008 was excluded due to the limited number of participating hospitals in Austria. Twenty-nine trauma centers (TCs) from Austria and nearly all German TCs (90%) contributed data to the TR-DGU.
Inclusion criteria: primary admission (i.e., no transfers in / no early transfer out < 48h), age ≥ 16 years, and Injury Severity Score (ISS) ≥ 16 points. The analysis was restricted to Austrian and German Level I trauma centers reporting to the TNW.
Austrian and German patient's data comparison was based on to the following criteria: The main focus of this study were pre-hospital times and interventions performed until the patient's care was taken over by the hospital's emergency room.

Statistical analysis
All parameters form the TR-DGU, including data from Austrian and German TCs were obtained from the same database. All comparisons are based on actual entries and no imputations for patients with missing data were performed. Categorical data are presented as percentages. Median and interquartile range (IQR) are shown for skewed data and mean with standard deviation (SD) otherwise. The level of statistical signi cance was thus set at P < 0.01 (Mann-Whitney-U-Test, Qui-Squared-Test). For the measure of association between dichotomous variables, the phi coe cient (Φ) was used to interpret the strength of relationship (-1: perfect negative relationship, 0: no relationship, 1: perfect positive relationship).

Pre-hospital time management
During the observed study period, inclusion criteria were met by 4.186 Austrian (AUT) and 41.670 German (GER) patients who represent the total study population (Fig. 1).
The overall required time for transport of patients from the accident site to the hospital did not differ signi cantly between Austria and Germany (P > 0.01) with a median of 62 minutes and an interquartile range (IQR) of 48-80 minutes versus 65 minutes and IQR of 50-85 minutes; a difference of 3 minutes respectively. The median on-scene time, indicating the amount of time it took the EMS team on the site of accident, was less in Austria, 25 minutes versus 28 minutes in Germany (P > 0.01). The transport time to the TC was 16 minutes in Austria and 17 minutes in Germany (Table 1). All transport times did not signi cantly differ between both countries (P > 0.01).

Mode of transportation
Transport to level I TCs was carried out with or without a physician. Overall, 95.1% of transports, HEMS (Helicopter transport) and EMS (Ambulance transport), were attended by a physician in Austria, which is almost equivalent to physician-accompanied transports in Germany, 95.9% (P = 0.011).
An obvious difference can be observed in the mode of transport. In Austria, 53.4% of trauma patients were transported to the emergency room via helicopter-based EMS compared to 36.6% in Germany (P < 0.001). In 46.6% of cases in Austria, patients were transported to the hospital by ground EMS compared to 63.4% in Germany (Fig. 2).

Pre-hospital interventions
Intubation in the pre-hospital setting was carried out at equivalent rates in both countries, 48.0% (Φ = 0.00). The proportion of chest tubes placed in Germany was 5.7% compared to 4.9% in Austria (Φ = 0.01). Catecholamines were administered to 12.3% of patients in Austria versus 13.4% in Germany (Φ = 0.01). A larger difference among the countries can be observed in the amount of sedation/analgesia received. A sedation was administered to 80.0% of patients in Austria and to 71.8% in Germany (Φ = 0.01). A further distinction applies to the perceived hemodynamic stability on accident site: A systolic blood pressure (BP) ≤ 90 mmHg was observed in 17.9% of Austrian patients and in 15.9% of Germans (Φ = 0.02). At the time upon arrival at the TC, 20.6% of Austrian patients were hemodynamically unstable with a systolic BP ≤ 90mmHg versus 14.7% in Germany (Φ = 0.05) (Fig. 3). Overall, no relationship between the abovementioned pre-hospital interventions can be observed between the countries.

Patients demographics
A blunt trauma was sustained by 96.0% of the entire study population with no difference between the two sub-populations. According to the mechanism of injury, Germany reported a higher rate of tra c accidents involving cars, motorcycles and bicycles. Patient's age did not differ between Germany, 51.3 ± 20.9 years with a mean ISS of 28.0 ± 11.9 points, and Austria, mean age: 50.1 ± 20.3 years, mean ISS: 27.9 ± 11.2 points. The observed American Society of Anesthesiologist (ASA) score 3-4 (http://www.asahq.org), referring to patients with a severe disease, was 16.8% in Germany versus 11.9% in Austria. This re ects a 4.9% difference, whereas the prevalence of relevant injuries within the four main body regions (AIS ≥ 3) did not differ between them. For all other parameters analyzed the frequencies were comparable between Austria and Germany and overall, the phi (Φ) coe cient revealed no relationship among the various demographic data (Table 3).

Discussion
Our analysis reveals that the pre-hospital management of severe trauma patients is rather similar between Austria and Germany. The observed results, based on registry data, include the pre-hospital management of patients.
The median overall time of transport and time on-scene of the EMS were 3 minutes shorter in Austria. The effect of this difference could be attributed to the mode of transportation (53.4% helicopter transport in Austria versus 36.6% in Germany). More than half (53.4%) of all Austrian trauma patients were transported to a TC with a helicopter, compared to 36.6% in Germany (P < 0.001). EMS in Austria are profoundly in uenced by its geographic alignment and population shifts during peak tourism seasons (Summer and Winter). Fifty percent of Austria's population lives in small towns or villages scattered all over the country, thereby creating a rural/urban split (50:50). This results in the necessity for adjustments in EMS strategies based on individual country sides. In rural areas, transport times are much longer as distances to medical facilities can be more than 60 km. Therefore, physician-staffed helicopters are predominately used in rural areas, especially in alpine regions where the exclusive usage of ground transportation is di cult or even impossible [8]. Currently, there are 38 helicopter EMS (HEMS) distributed throughout Austria and cover an area of 84.000 square kilometers (1:2211 square kilometers) and 89 in Germany, covering 356.000 square kilometers (1:4000 square kilometers) [9]. In addition, all of the Western, as well as most of the Southern and Central parts of Austria are covered by the Alps where some mountains reach altitudes of up to 3800 meters, relying therefore on a physician-based HEMS [8]. Another reason that might explain the high percentage of helicopter usage in Austria is the increase in the number of trauma patients due to tourism. According to http://www.austria.info, in 2018, 149 million overnight stays by tourists from all over the world were accounted for.
Nevertheless, the potentially bene cial effects of HEMS on patients' outcomes and cost e ciency are still controversially discussed [23]. In summary, trauma patients bene t from HEMS rescue with in-hospital survival as a main outcome parameter. Analyzing different subgroups, older patients, low-energy trauma, and minor injury severity had the most pronounced survival bene t when rescued by HEMS [24]. However, according to the Austrian (OEAMTC) and German (ADAC) Automobile Club, overall, 17.281 and 53.967 HEMS transports to the ED respectively have been carried out in 2019. This correlates to 1.942 HEMS transports per 1 million inhabitants in Austria and 650 transports per 1 million in Germany. The large difference in helicopter transports can further be explained by the overall lack of a regional/national uni ed algorithm of indications/guidelines for transport. We suggest to explicitly use the HEMS system for trauma patients only a) for the rescue/care of people who have had an accident or are in lifethreatening situations, b) for the transport of emergency patients with ISS > 16, c) for transport of rescue or recovery personnel to hard-to-reach regions or, d) for the transport of medicinal products, especially blood products, organ transplants or medical devices. In summary, the usage of the HEMS system in Austria compared to Germany seems too high and should be reevaluated in terms of its on-scene relevance.
Further, this study demonstrates a discrepancy in the pre-hospital uid administration. A signi cant difference between the countries was observed for the amount of uid administered on scene, a median of 500 mL in Austria versus 1000 mL in Germany. This may be due to differences in uid administration habits, as it can be seen in Switzerland [25] and in the Dutch [6] population as well, where 30% less uid in the pre-hospital setting is being administered when compared to Germany. Kudo et al. elaborate on the importance on achieving a balance between organ perfusion and hemostasis which is critical for optimal uid resuscitation in trauma patients. "Permissive hypotension" refers to managing trauma patients by restricting the amount of resuscitation uid and maintaining blood pressure in the lower-than-normal range if there is continuing bleeding during the acute period of injury. However, no study has investigated which subjects would bene t most from this approach, when considering factors such as age, injury mechanism, setting, or the presence or absence of hypotension [26]. The in uence of these approaches on coagulation has not been su ciently examined, even in animal studies and the overall effectiveness of permissive hypotension/ hypotensive resuscitation is still inconclusive and mandates further research [10][11][12]21].
There is no evidence on the required volume threshold for trauma patients [13]. Driessen et al. state that the mean Base Excess (BE) at the time of admission to the ED might indicate a better tissue perfusion despite low BP [14]. In Austria, 20.6% compared to 14.7% of Germans arrived at the TC in a hemodynamically unstable condition, associating with a systolic BP of ≤ 90mmHg. The administration of catecholamines recruits unstressed blood volumes and in uences the maintenance of blood pressure [15]. This might be a possible explanation of why the observed hemodynamic instability of Austrian patients arriving at the TC was higher as well as the reduced amount of uid administered on scene. It can further be excluded that the administration of Tranexamic Acid (TXA) is responsible for the difference in systolic BP upon arrival in the TC, as it was equivalent in both countries. Overall, no algorithm on the exact and correct amount of uid volume in the pre-clinical setting can be recommended by the authors as it is a dependent variable of age, anticoagulation, blood loss and observed injury pattern.
The mechanism of injury as well as various demographic characteristics do not show a relationship amongst individual variables between both countries and were similar to those found in other studies conducted with the TR-DGU [4,6,7,20]. In General, results should primarily be interpreted in terms of their clinical relevance because the large sample size included in this study likely yields a formal signi cance even in case of minor differences. Although, a notable variation can be observed by combining geriatric age groups (≥ 70 years) of transported patients within one country. It can be emphasized that more severely injured geriatric patients were transported to TCs in Germany compared to Austria. This further correlates with a greater observed ASA score [16,17] in Germany as patients age increases. Spering et al. suggest that the number of patients with pre-existing medical conditions, classi ed according to ASA ≥ 3, increase with accumulative age. Hence, as the age of injured patients rises, so does the cumulative percentage of ASA 3-4 [22]. Overall, a larger number of geriatric patients in Germany have been included in this retrospective data analysis, correlating with a higher observed ASA score (Class 3-4). This classi cation score includes patients with moderate to severe systemic disease and functional limitations up to a severe systemic disease, which is a constant threat to life [18].

Limitations
This retrospective study was conducted using data from a large registry but does not include data from all Austrian TCs. Therefore, the completeness of the submitted data resulted in limitations. Further, the veri cation of entered data correctness, according to the TR-DGU, was performed only in a small sample of cases. The reported differences in the results could be due to statistical random ndings (type I and II error), differences in care and various treatment protocols. Despite the limitations of trauma registries, it serves as a means for quality control and helps to assist in optimizing treatment protocols.

Conclusion
There was no meaningful difference between Austria and Germany based on basic demographic characteristics. The on-scene time of EMS arrival was 3 minutes shorter in Austria probably due to the predominant usage of HEMS. Although geographic alterations and tourism might help explain the signi cant higher number of helicopter transports in Austria, the authors suggest implementing an international guideline to explicitly use the HEMS system for speci c indications. Overall, the amount of administered uid in the pre-clinical setting should follow the concept of permissive hypotension/ hypotensive resuscitation especially in younger patients but is still inconclusive and mandates further research. Further, quality control and registry comparisons should be a fundamental part of trauma patient treatment in hospital organizations. Availability of data and materials: The data that support the ndings of this study are available from TraumaRegister DGU ® but restrictions apply to the availability of these data, which were used under license for the current study, and so are not publicly available. Data are however available from the authors upon reasonable request and with permission of Rolf Lefering.