The effect of Helicopter Emergency Medical Services on trauma patient mortality in the Netherlands
Introduction
In the Netherlands, all emergency medical services (EMS) are staffed by paramedics who have years of clinical experience and education (e.g., in intensive care or emergency medicine), supplemented with three additional years of specific ambulance training. All paramedics are Pre-Hospital Trauma Life Support (PHTLS) certified. Since 1997, in addition to the EMS, Helicopter Emergency Medical Services (HEMS) have been available to provide on-scene assistance to trauma patients. The aim of the HEMS is to provide an on-demand upgrade to standard care at the scene to improve the outcome of severely injured patients. The HEMS is always staffed by a specially trained anaesthesiologist or trauma surgeon and nurse. HEMS is called in by the same EMS dispatcher who dispatched the EMS to the scene, based on criteria like suspicion of high energetic trauma, entrapment and drowning or secondary criteria based EMS on-scene observations of patient conditions.1 The dispatch of the HEMS is not related to distance because of the relatively short distances to hospitals in the Netherlands.2 The specific dispatch criteria approved by the Ministry of Health are shown in Table 1.1 Patients are transported to a hospital predominantly by ambulance. Currently, there are four HEMS (in Groningen, Amsterdam, Rotterdam, Nijmegen) that can reach about 75% of the Dutch population within 13 min of dispatch.1, 3
The St. Elisabeth Hospital in Tilburg is a level I trauma centre in the middle of Noord-Brabant county. The hospital serves an area of 5082 km2 and 2.4 million inhabitants.4 The hospital does not have its own HEMS. The hospital is served by the HEMS of Nijmegen and Rotterdam, which are just outside the county borders. In Noord-Brabant, five teaching and seven non-teaching hospitals are capable of resolving acute problems concerning airway, breathing and life-threatening haemorrhaging. All of these hospitals can be reached within 15 min by ambulance from anywhere in the county. The St. Elisabeth Hospital has a large neurosurgical unit. Patients with severe head injury are either taken directly from the scene to the unit or are secondarily transferred from a primary hospital after stabilisation. Because of the flat Dutch topography, short distances and a high hospital density, the EMS dispatcher does not have much difficultly in sending EMS for “scoop and run” of patients without dispatch of the HEMS.
The main goal of the introduction of the HEMS in 1997 was to improve the survival chances of severely injured patients. However, the value of the HEMS is still a subject of discussion, and scientific evidence to support the benefits of the HEMS in the Netherlands is still scarce. In addition, the role of time from trauma until definitive diagnosis and medical treatment in the survival of severely injured patients remains unclear in prehospital care.2, 5, 6, 7 In the present study, the assumption that treatment by the on-scene HEMS decreases the mortality of trauma patients was investigated. Also, the effect of time between trauma and hospital treatment on the association between treatment by HEMS and mortality was studied.
Section snippets
Trauma registry and study population
In the Netherlands, both immediately admitted trauma patients and secondary referrals are registered in a prospective, comprehensive nationwide registry. Trauma victims who are dead on arrival or who die in the emergency department of a hospital are also included. The validated Abbreviated Injury Scale (AIS-90, update 98)8, 9 is used to define the severity of separate injuries and forms the basis of the ISS that assesses overall trauma severity. To compute the ISS, each of six anatomical
Results
The mean age of the study population (n = 372) was 37.8 with a standard deviation (SD) of 20.3 years, and 25% (n = 93) were female. The mean ISS was 22.7 (SD 14.2), and 43% of patients (n = 158) suffered TBI.
Table 2 shows the differences between patients treated by EMS only and patients treated by EMS and HEMS categorised by whether or not the patient suffered TBI. The ISS of the patients with TBI and treated by EMS only was not significantly lower (30.8, SD 11.6) than the ISS of the patients treated
Discussion
In the present study, the value of a HEMS, staffed by a trained and experienced anaesthesiologist or surgeon, added to the regular EMS by ambulance, staffed by highly trained and experienced paramedics, in improving mortality outcomes for trauma victims in the Netherlands was investigated. A group of patients treated by the EMS with the assistance of the HEMS was compared to a matched group of patients treated by the EMS only. The patients were matched by ISS, age, gender, mechanism of trauma
Conclusions
Our results cannot prove the benefit of the HEMS in the Netherlands and suggest in particular for TBI patients that prehospital times should be shortened to decrease in-hospital mortality.
Conflict of interest statement
There are no conflicts of interest.
Acknowledgment
We thank the regional EMS services for providing access to their registration systems.
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