Introduction

In Germany, the emergency medical services (EMS) are considered to be among the best in the world. An essential feature is that specially qualified EMS physicians treat patients at the scene and can also perform further emergency interventions if necessary [8]. As a consequence, formal qualifications for EMS physicians have been established. In addition to participating in theory courses, a minimum requirement has been established for previous clinical and intensive care experience and the number of supervised scene calls. When these criteria have been fulfilled and, also as of recently, after passing an oral examination conducted by the appropriate state medical board, an EMS physician is certified for both air and ground scene calls [24].

Ideally, EMS physicians should be dispatched depending on the patient’s condition, the kind of emergency and according to critieria established in an indication catalogue. This enables the dispatch center to take the time element into account as well when calculating the distance between the location of the EMS unit and the emergency site for dispatching the EMS team [12]. The EMS dispatch center assumes that the quality provided by all available EMS units is identical. In addition to the theoretical qualifications, the quality of an EMS system depends in particular on clinical routine and experience of staff in managing demanding or complex emergency situations [22]. Especially because a high proportion of scene calls are not considered to be life-threatening, it seems all the more important to consider how often an EMS team encounters situations that are classified as demanding rather than the absolute numbers of scene calls [1].

Since no data for Germany are currently available to document the occurrence of very difficult scene calls, the present study was carried out to address the question how often EMS physicians encounter defined difficult situations and carry out certain emergency interventions in both ground and helicopter EMS scene calls. Particular emphasis was placed on acute coronary syndrome (ACS), stroke, multiple trauma, as well as head injury, which have been defined as tracer diagnoses in emergency situtations [23].

Materials and methods

As part of the seminar “Invasive Emergency Techniques (INTECH)” that is offered annually to EMS staff by the Department of Anesthesiology and the Second Department of Anatomy of the University of Heidelberg since 2001, participants were asked to complete a questionnaire which was prospective and anonymous in design.

In addition to personal information provided by the seminar participants, we also analyzed data from the MIND (“minimaler Notarztdatensatz”) registry, which was compiled by the state medical association of Baden-Wuerttemberg, Germany, from 1st January 2002 to 30th June 2004, to determine how often certain kinds of ground EMS scene calls were carried out in the entire state [17]. Permission to include this data was granted by both the state medical association and the institute that conducted the MIND study (AQAI, Nierstein, Germany). We focused on information pertaining to the incidence of tracer diagnoses and emergencies such as ACS, stroke, head trauma, multiple trauma, pediatric emergencies and emergency procedures such as cardiopulmonary resuscitation, intubation, intubation not associated with cardiopulmonary resuscitation and inserting a chest tube.

To investigate possible differences among the various EMS systems, we also evaluated data from the “Luftrettungs-, Informations- und Kommunikationssystem” (LIKS) database of the German Automobile Association (ADAC) air rescue service for the time period 2002–2003. As of 31st December 2003, LIKS had included 25 ADAC air rescue centers and 3 units supported by the Germany Federal Department of the Interior. After excluding the 4 helicopter EMS centers designed as intensive care transport only, data for 47,184 primary scene calls from 24 air rescue centers could be further evaluated [23].

The definitions of scene calls or emergency procedures for the two EMS systems are outlined in Tab. 1. It is important to note that the severity of the illness or injury is only included in the definition of multiple trauma. We then calculated the individual frequency of encountering certain emergency situations and carrying out certain emergency procedures from the individual data as per the anonymous questionnaire given at the INTECH seminars and correlated them with the MIND data and the data from the helicopter EMS units using the following formulae:

Tab. 1 Definition (as indicated in the EMS physician’s report) of the tracer diagnoses and procedure according to the MIND registry of the state medical association of Baden-Wuerttemberg and the LIKS database of the ADAC air rescue services
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$$ \begin{aligned} & {\text{no}}{\text{.}}\;{\text{of scene calls per month}}_{{{\left( {{\text{emergency physican}}} \right)}}} \times {\text{frequency}}_{{{\left( {{\text{scene call MIND/Air Rescue}}} \right)}}} \\ & = {\text{no}}{\text{. per month}}_{{{\left( {{\text{scene call}}} \right)}}} \\ \end{aligned} $$
(1)
$$ {\text{1/no}}{\text{. per month}}_{{{\left( {{\text{scene call}}} \right)}}} = {\text{Time in months to encountering}}_{{{\left( {{\text{scene call}}} \right)}}} $$
(2)

Definitions of the variables used in these formulae are summarized in Tab. 2.

Tab. 2 Definitions of variables used in calculating the individual frequency of certain kinds of scene calls and emergency interventions
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The absolute numbers are given either as mean±standard deviation or frequency with respect to the total number of missions in percent. Differences between the emergency missions carried out by ground EMS systems (MIND study) and the ADAC air rescue services were computer analyzed using the χ2-test. A value of p<0.05 was considered statistically significant. Since all other calculations were based on the frequency we did not carry out any further statistical analysis of the data.

Results

A total of 154 fully completed questionnaires from EMS physicians working in southwestern Germany (male/female: 91/63) could be evaluated. At the time of the questionnaire, the average age of the EMS physicians was 38±7 years (range 27–58 years, median 36 years) and the average professional experience was 9±6 years (range 1–28 years, median 6 years). Of the participants, 86 (56%) said they worked in the field of anesthesiology, 27% in internal medicine, 14% in surgery and 3% in general medicine or gynecology. The rate of board certification was 43%. At the time of the questionnaire, the participants had been working as EMS physicians on average for 6±6 years (range 0.5–26 years, median 4 years). The average scene call frequency was given as 16±11 per month (range 3–60, median 14; Tab. 3).

Tab. 3 Characteristics of the EMS physicians participating in the Heidelberg INTECH seminars 2001–2004 according to the questionnaire (n=154)
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According to the MIND data, 82,002 scene calls were registered for the time period from 1st January 2002 to 30th June 30 2004 and could be evaluated. Likewise, for the time period 1st January 2002 to 31st December 2003, the LIKS database included 47,184 primary ADAC air rescue scene calls that could be studied. To calculate the incidence of scene calls, we did not just evaluate missions that involved treating patients but rather the total number of scene calls, as indicated in the questionnaire.

With respect to our definitions, the frequency of the individual scene calls in the study period and the frequency of certain emergency medical procedures for MIND vs. LIKS, respectively, are summarized in Tab. 4.

Tab. 4 Number of certain kinds of scene calls and interventions carried out and time period (in months) before encountering such an emergency again in ground and helicopter EMS scene calls with 16 scene calls per month as per INTECH (n=154), MIND (n=82,002) and ADAC (n=47,184) data
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The diagnosis of acute coronary syndrome was made significantly more often in ground rescue than in air rescue missions (ratio 1.4, p<0.01). In contrast, the diagnosis or emergency treatment of apoplexy (ratio 1.3, p<0.05), head and brain trauma (ratio 1.5, p<0.05), multiple trauma (ratio 11.4, p<0.001), pediatric emergency (ratio 1.2, p<0.05), resuscitation (ratio 1.2, p<0.05), intubation (ratio 3.1, p<0.01), intubation not associated with resuscitation (ratio 5.6, p<0.001) and placing a chest tube (ratio 13.8, p<0.001) were identified significantly more frequently in air rescue missions.

According to the subjective data of the INTECH participants at 16 emergency missions per month and with respect to the data from the MIND and LIKS evaluations, formula 1 shows that on average, on ground rescue missions emergency physicians treated 2–3 patients with ACS per month (2.6) and 1 patient with apoplexy (1.2). On air rescue missions emergency physicians encountered ACS at 1.9 patients per month less often and apoplexy at 1.6 patients per month somewhat more frequently.

Emergency physicians encountered all other emergency situations less frequently. The averages per month for ground rescue and air rescue missions, respectively, were as follows: head and brain trauma 0.56 and 0.86 patients, multiple trauma 0.07 and 0.78, pediatric emergency 0.78 and 0.95, emergency resuscitation 0.64 and 0.75, intubation 0.71 and 2.17 (intubation not associated with resuscitation 0.27 and 1.5 patients) and placing a chest tube 0.01 and 0.18. These findings are summarized in Tab. 4 and Fig. 1.

Fig. 1
figure 1

Number of certain kinds of scene calls and interventions carried out in ground and helicopter EMS scene calls for 16 scene calls per month as per the INTECH (n=154), MIND (n=82.002) und ADAC data (n=47.184)

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According to formula 2, the time intervals (in months) between the same emergency situation, i.e., the time that passed until an emergency physician encountered a certain situation again as a ground rescue mission (or air rescue mission), were 0.4 (0.5) months for acute coronary syndrome, 0.8 (0.6) for apoplexy, 1.8 (1.2) for head and brain trauma, 14.5 (1.3) for multiple trauma and 1.3 (1.1) for pediatric emergencies.

Every 1.6 (1.3) months an emergency physician encountered a resuscitation situation, intubated a patient every 1.4 (0.5) months before reaching the clinic, not associated with resuscitation every 3.7 (0.7) months and placed a chest tube every 76.5 (5.7) months. A summary of these results is presented in Fig. 2.

Fig. 2
figure 2

Frequency (time between the same kind of scene call in months) of encountering certain scene calls in ground and helicopter EMS scene calls at 16 scene calls per month as per the INTECH (n=154), MIND (n=82.002) und ADAC data (n=47.184)

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Without distinguishing between the individual kinds of emergencies, the proportion of the missions classified as NACA (National Advisory Committee of Aeronautics) IV (life-threatening situation cannot be excluded), V (acutely life-threatening) and VI (successful resuscitation) in the MIND registry for ground missions was 37.6% and for air rescue 35.1% (ratio ground to air 1:1, not statistically significant).

Discussion

This study shows that some EMS physicians only encountered demanding emergency situations very rarely. While both ground and helicopter EMS crews treated about two ACS or strokes every month, the likelihood of helicopter EMS staff managing head and multiple trauma, pediatric emergencies, intubating or inserting chest tubes was significantly higher than in ground EMS units. The significantly higher incidence of these emergency procedures can be explained at least in part by the fact that patients with head trauma were treated during helicopter vs. ground EMS scene calls 1.5 times more often and patients with multiple trauma 11.4 times more often. When interpreting our data, the severity of the illness or injury was only taken into account for multiple trauma cases, for which the NACA score had to be either V or VI. For the other emergency situations, diagnoses and procedures, however, the level of danger to lose life or limb remained speculative. The question is whether patients encountered in ground EMS scene calls were less severely ill or injured than those encountered in helicopter EMS scene calls. Without distinguishing between the individual diagnoses, however, the NACA scores IV–VI in 37.6% of ground EMS vs. 35.1% in helicopter EMS scene calls did not confirm this assumption.

A recent validation study of prehospital NACA scores to assess the severity of illness or injury showed that strong subjective influence and expectations of the EMS physicians played a role and that the score was often incorrect or too low. With respect to objective parameters, the rate of patients with a NACA IV–VI score in helicopter EMS scene calls was found to be 70% in this study [25]. The lack of optimal coordination of scene calls by dispatch centers, which has resulted in a high percentage of aborted scene calls, is another issue and cannot be addressed in this study [1]. A limitation of our study is that further calculations in a large number of scene calls were based on the results of a questionnaire and not on directly obtained data. Although the questionnaire was anonymous, it may be prone to subjective influence.

Although workshop participants might be more motivated than average, they may also be less qualified thus representing a selective and possibly non-representative cohort. In the future, it would certainly be desirable to register the actual total and individual number of scene calls per month in a given location in a large cohort of EMS physicians. Furthermore, it would be interesting to assess to what extent EMS physicians work in more than one EMS service simultaneously.

In our opinion, self-characterization of the interviewed EMS physicians and the calculated number of an average 16 scene calls per month is realistic. Although an EMS system with ~1,500 scene calls per year may be relatively low-volume in a metropolitan area, it would be high-volume for rural locations. This would indicate that our interviewed EMS physicians worked 3 shifts monthly with 4–5 scene calls each. The difference between 2–60 scene calls per month indicates for certain individuals not only a much higher but also a considerably lower individual incidence for certain kinds of scene calls than calculated. However, the performance survey from the EMS services in Germany 2000 and 2001 reporting 110 annual scene calls per EMS physician, indicates that the subjective assessment of the monthly number of missions is too high and therefore the intervals between certain kinds of emergencies are even greater [4]. Although the seminar participants indicated that they had an average of 6 years EMS experience, the rate of board certification was only 43%, while it was 53% for MIND data and 66% for the LIKS database. While subspecialties from the INTECH participants vs. MIND data were comparable (anesthesiology 56% vs. 58%, surgery 14% vs. 13%, internal medicine 27% vs. 23% and other 3% vs. 6%), most (76.1%) of helicopter EMS physicians were anesthesiologists, with only some surgeons (14%), internists (8.4%) and others (1.2%).

Reported intervention frequencies were taken exclusively from EMS physician’s reports and a blinded study design was not employed. Furthermore, whether the EMS physician’s diagnosis, the NACA score and the procedures carried out were correctly documented or indicated is not known. In addition to possible subjective influences on the NACA score, prehospital diagnosis and estimation of illness or injury severity may not always correspond to hospital assessment [2, 25]. Furthermore, EMS physicians who determine that treating severely injured and pediatric emergency patients is extremely stressful, often deliberately do not carry out invasive emergency interventions, suggesting that the diagnosis, degree of trauma severity, or the degree of threat to life may not always be objectively documented [27]. Current data from hospitals admitting emergency patients showing sometimes serious clinical management deficiencies in pediatric emergency and multiple trauma patients, indicate that Germany has not yet developed the best and most qualified EMS service in the world [7]. Prehospital management fails especially for those patients who require manual technical skills, such as creating adequate intravascular access employing intraosseous access, intubation and inserting a chest tube [3, 6, 10, 14, 15, 19, 20]. Our experience is also in full agreement with this data that EMS physicians often do not carry out these interventions [27].

Only limited data is available on how many interventions need to be done over time in order to effectively perform a previously learned intervention [13]. For example, the number of required intubations before it can be performed safely, correctly and without help in 90% of patients is 57 and even after 80 intubations, 18% of study subjects would still require help from experienced colleagues [13]. Although management of complicated emergency situations is not restricted to the technical manual skill levels [22], these studies impressively demonstrate that the number of a given intervention required for board certification or additional EMS certification is not always sufficient to ensure that these interventions can be confidently performed under emergency conditions and maintained for a longer period of time. In our opinion, EMS physicians should be required to work continuously in anesthesiology, emergency departments or intensive care units in order to maintain their skills. This is underlined by current simulator-supported studies showing that anesthesiology, emergency department or intensive care physicians managing emergency situtations such as anaphylaxis, acute myocardial infarction, ventricular tachycardia, intracranial bleeding and aspiration, do significantly better than physicians not working in these areas [18]. Seldomly required, possibly life-saving manual techniques should be learned and continuously practiced in strictly “hands-on” seminars using modern simulation techniques [9, 26, 27].

Limiting the number of EMS physicians practicing in a given location may contribute to maintaining the greatest possible individual experience. Furthermore, the present results could suggest that not only location but also the actual performance capability of an EMS system should be accounted for in dispatch strategies. Interestingly, investigations of chest trauma have shown that scene times were considerably longer for ground vs. helicopter EMS systems even though twice as many chest tubes were placed before initiation of transport [2]. Introduction of flat case rate reimbursement in Germany, closing of hospitals and the fear that smaller emergency facilities will be closed because of a lack of physicians and low number of scene calls, may indicate that certain areas will be covered by competent, but more distant EMS units; however, this does not necessarily represent a disadvantage for patients with life-threatening conditions [5, 11, 16, 21].