Entrenamiento en soporte vital avanzado de traumatismos para el personal de ambulancias
Resumen
Antecedentes
Existe un aumento en la carga global de las lesiones, especialmente en los países de ingresos bajos y medios. Para abordar este problema, los modelos de atención traumatológica desarrollados inicialmente en los países de altos ingresos se adoptan actualmente en el ámbito de los países de ingresos bajos y medios. En particular, en los países de ingresos bajos y medios se promueve el entrenamiento en soporte vital avanzado (SVA) del personal de ambulancias como una estrategia para mejorar los resultados de las víctimas de traumatismos. Sin embargo, existe controversia sobre la efectividad de esta intervención en los servicios sanitarios y las pruebas todavía se deben evaluar rigurosamente.
Objetivos
Cuantificar la repercusión del personal de ambulancias entrenado en SVA versus el personal sin entrenamiento en SVA sobre la reducción de la mortalidad y la morbilidad en pacientes con traumatismos.
Métodos de búsqueda
Se realizó una búsqueda de estudios el 16 de mayo de 2014. Se hicieron búsquedas en el Registro Especializado del Grupo Cochrane de Lesiones (Cochrane Injuries Group's Specialised Register), el Registro Cochrane Central de Ensayos Controlados (Cochrane Central Register of Controlled Trials, CENTRAL, la Biblioteca Cochrane), Ovid MEDLINE(R), Ovid MEDLINE(R) In‐Process & Other Non‐Indexed Citations, Ovid MEDLINE(R) Daily y Ovid OLDMEDLINE(R), Embase Classic+Embase (Ovid), ISI WOS (SCI‐EXPANDED, SSCI, CPCI‐S & CPSI‐SSH), CINAHL Plus (EBSCO), PubMed y se examinaron las listas de referencias.
Criterios de selección
Ensayos controlados aleatorizados, ensayos controlados y estudios no aleatorizados, incluidos los estudios del tipo antes y después (before and after studies) y los estudios de series de tiempo interrumpido, que compararon la repercusión del personal de ambulancias entrenado en SVA versus el personal sin entrenamiento en SVA sobre la reducción de la mortalidad y la morbilidad en pacientes con traumatismos.
Obtención y análisis de los datos
Dos autores de la revisión evaluaron los informes de los estudios de acuerdo con los criterios de inclusión y extrajeron los datos.
Resultados principales
Se encontró un ensayo controlado del tipo antes y después, un estudio no controlado del tipo antes y después, y un ensayo controlado aleatorizado que cumplieron los criterios de inclusión. Ninguno demostró evidencia para apoyar el entrenamiento en SVA del personal prehospitalario. En el estudio no controlado del tipo antes y después, un análisis de subgrupos "a priori" mostró un aumento de la mortalidad entre los pacientes con una puntuación menor de 9 en la Glasgow Coma Scale (escala de coma de Glasgow) y que recibieron atención del personal de ambulancias entrenado en SVA. Además, cuando se tuvo en cuenta la puntuación de traumatismo prehospitalario en el análisis de regresión logística, la mortalidad de los pacientes que recibieron atención del personal entrenado en SVA aumentó significativamente.
Conclusiones de los autores
Actualmente la evidencia indica que no hay beneficios del entrenamiento en soporte vital avanzado del personal de ambulancias sobre los resultados del paciente.
PICOs
Resumen en términos sencillos
Entrenamiento en soporte vital avanzado de traumatismos para el personal de ambulancias
Las lesiones son una de las diez causas principales de muerte y discapacidad a nivel mundial. Lo anterior da lugar a una pérdida precoz de la vida de muchos jóvenes y a un aumento constante de los costos de la atención médica en los supervivientes. Se considera que el entrenamiento en soporte vital avanzado (SVA) para el personal de ambulancias con énfasis en traumatismos ha contribuido a una reducción del número de muertes por lesiones en los países de ingresos predominantemente altos donde se dispone de este servicio. Los servicios de SVA también se han adaptado para los países de bajos y medios ingresos. Esta revisión de ensayos encontró que no existen pruebas que indiquen que el entrenamiento en SVA para el personal de ambulancias mejora los resultados para los pacientes con lesiones.
Authors' conclusions
Background
The epidemiological, demographic, and socio‐political transitions underway in many countries are associated with an increasing burden of disease from injury, particularly in low‐ and middle‐income countries (LMICs). These findings have been highlighted by the Global Burden of Disease Study, which identified injury as one of the top ten causes of death and disability worldwide (Murray 1997a; Murray 1997b; Murray 1997c; Lopez 2006). That study also predicted that the incidence of injury was likely to increase by the year 2030 (Mathers 2006). Although infectious diseases are still extremely important causes of death in LMICs, the challenges of injury and non‐communicable disease add to these as important causes of premature mortality and morbidity (Gwatkin 1997). Injuries place a disproportionately large burden of disease on young people (Murray 1997a; Murray 1997b), and, consequently, are a leading cause of premature loss of productive life, of high medical care costs, of significant degrees of disability and of large socio‐economic loss to society (Berger 1996).
There have been recent calls by the public health community and civil organisations to formulate a strategy to decrease the burden from injuries. While responding to injuries requires considerable attention to preventive efforts (Berger 1996), improvements in health care provision which reduce deaths, disability and societal costs are also required (Sethi 2000). In many high income countries (HICs), reductions in trauma mortality of 15% to 20% have been achieved in the last few decades (Cales 1984; Roberts 1996; Lecky 2000), which may be partly as a result of improved systems for trauma care. Advanced life support (ALS) training for ambulance personnel is considered to have made an important contribution to the reduction of trauma mortality in HIC settings (Kirsch 1998; Reines 1998). ALS‐trained ambulance crews receive extra training in endotracheal intubation, intravenous cannulation, the administration of intravenous fluids, and the use of selected drugs (Calicott 1980). In high‐income countries a substantial proportion of ambulance crews now include an ALS‐trained officer. For example, in the UK, Department of Health policy requires that all emergency ambulances include an ambulance officer trained in ALS (AACE 2013; DoH 2011; JRCALC 2010).
In response to the increasing global burden of injury, LMICs are rapidly adopting models of trauma care initially developed in high‐income countries, such as ALS training for ambulance crews to improve outcomes in injury victims (Ali 1993; Sethi 2000). In many LMICs, the majority of patients arrive by private transport, although many countries have been developing pre‐hospital care services further (Hauswald 1997; Areola‐Risa 2000). As LMICs consider various models of pre‐hospital care, the use of ALS training for ambulance crews has been debated (Sklar 1988; VanRooyen 1999). Little systematic evaluation of existing evidence is available for such policy‐making.
Why it is important to do this review
The evidence for the impact of ALS‐trained ambulance crews has yet to be rigorously appraised. The aim of this systematic review is therefore to quantify the impact of ambulance crews with ALS training on outcomes following trauma.
Objectives
To quantify the effects of ALS‐trained ambulance crews versus crews without ALS training on reducing mortality and morbidity in injured patients.
Methods
Criteria for considering studies for this review
Types of studies
Randomised controlled trials (RCTs), controlled trials (CTs), before‐and‐after (CBAs, BAs) and interrupted time series (ITSs) studies.
Types of participants
All adult trauma patients over 18 years.
Types of interventions
ALS‐trained ambulance crews with specific trauma training (including ATLS or PHTLS or other equivalent) versus crews without ALS training.
Types of outcome measures
-
Death from all causes at the end of the follow‐up period scheduled for each study
-
Morbidity
Search methods for identification of studies
In order to reduce publication and retrieval bias we did not restrict our search by language, date or publication status.
Electronic searches
The Cochrane Injuries Group's Trials Search Co‐ordinator searched the following:
-
Cochrane Injuries Group Specialised Register (16th May 2014);
-
Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library) (issue 4 of 12, 2014);
-
Ovid MEDLINE(R), Ovid MEDLINE(R) In‐Process & Other Non‐Indexed Citations, Ovid MEDLINE(R) Daily and Ovid OLDMEDLINE(R) 1946 to 16th May 2014;
-
Embase Classic+Embase (OvidSP) 1947 to 16th May 2014;
-
ISI Web of Science: Science Citation Index Expanded (SCI‐EXPANDED) (1970 to May 2014);
-
ISI Web of Science: Conference Proceedings Citation Index ‐ Science (CPCI‐S) (1990 to May 2014);
-
CINAHL Plus (EBSCO Host) 1937 to May 2014;
-
PubMed (16th May 2014).
The search strategies are also used for the review 'Advanced trauma life support training for hospital staff' (Jayaraman 2014) and are given in Appendix 1.
Searching other resources
We screened the reference lists of all trial reports included in the review to identify any further published and unpublished data.
Data collection and analysis
Selection of studies
One review author (SJ) screened the search results and applied the inclusion criteria.
Data extraction and management
Two review authors (SJ and RW) extracted information on the following: study design, stratification for effect modifiers, method of allocation concealment, number of randomised patients, type of participants, and interventions and outcomes. The outcome data sought were mortality and morbidity. The review author was not blinded to the authors or journal when doing this, although evidence for the value of blinding the review authors is not conclusive (Berlin 1997).
Assessment of risk of bias in included studies
We assessed study quality using the recommendations outlined in chapter 8 of the Cochrane Handbook for Systematic Reviews of Interventions to determine the degree to which systematic bias may have been introduced, such as: bias through selection, performance, exclusion or detection; the method of allocation; the degree of follow‐up, and the soundness of the assessments. Two review authors (SJ and RW) categorised the studies as RCTs, CCTs, BAs and ITSs and applied these specific categories of quality assessment to the trial reports.
Assessment of heterogeneity
The groups of trials would have been examined for statistical evidence of heterogeneity using the Chi2 test. If there was no obvious heterogeneity on visual inspection or statistical testing, pooled relative risks and 95% confidence intervals would have been calculated using a fixed‐effect model.
Subgroup analysis and investigation of heterogeneity
The following comparisons were planned:
Mortality and morbidity of victims of trauma treated by ALS‐trained ambulance crews versus crews without ALS training. 'A priori' sub‐group analyses reported by studies were evaluated to look for statistically significant differences that were not apparent in the overall analyses.
The intended analysis was the calculation of relative risk of death and 95% confidence interval for each trial, such that a relative risk of more than one indicates a higher risk of death. We chose relative risk as it can be more readily applied to clinical situations.
Sensitivity analysis
The effect of excluding trials judged to be inadequate according to the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011) criteria for quality would have been examined in a sensitivity analysis.
Results
Description of studies
Results of the search
The search covered all years to May 2014. The process of identifying new studies is given in Figure 1. Three studies are included in this review.
Study flow diagram.
Included studies
Arreola‐Risa 2004
This was a controlled before‐and‐after study on mortality from injury in three Mexican cities (Monterrey, San Pedro and Santa Catarina). In San Pedro, ambulance staff received training in Basic Trauma Life Support (BTLS), Advanced Cardiac Life Support, and a locally designed airway course. In Monterrey, ambulance staff received training in pre‐hospital Trauma Life Support (a BTLS equivalent). In Santa Catarina, no additional training was provided (i.e. this was the control group). Before and after comparisons were made in Monterrey in 1994 and 1995, and in 2000 and 2001 for both San Pedro and Santa Catarina. Data were collected using self‐reported ambulance‐run sheets. The main treatment outcome was mortality from trauma. Secondary outcomes included effects of training on use of three specific skills and arrival time.
The number of trauma patients treated by ambulance personnel during the study period were 866 in Monterrey, 510 in San Pedro, and 504 in Santa Catarina. The injured patients were predominantly male and sustained mostly blunt injuries. In the follow‐up period, patients in Monterrey (BLS group) received statistically greater numbers of all procedures for the three key management areas: airway management, fluid resuscitation and spinal immobilisation whereas patients in San Pedro (ALS group) received better management in some areas but not all. Management of these three areas were unchanged in Santa Catarina (the control group). However, despite these improvements in process indicators in Monterrey and to a lesser extent in San Pedro, the study demonstrates no statistically significant change in mortality in any of the three settings. When deaths on scene were excluded, there was a small trend towards lower mortality among injured patients in Monterrey (BLS group) but not in the other two settings.
Nicholl 1998
This RCT compared outcomes of victims of trauma treated by ambulance crews with ALS training to outcomes of those treated by crews without ALS training. Participants were trauma (road traffic accidents, falls, work/chemical/sport accidents, self‐harm, assaults and drowning) patients of all ages. People with superficial injuries were excluded. Follow‐up was six months after the original incident and was performed using the SF‐36 questionnaire. Protocol compliance was poor. The authors did not recruit sufficient numbers because of practical difficulties. The mortality and morbidity data of the randomised group were added to the main non‐randomised cohort in the original analysis. Therefore, specific analysis of the randomised patients cannot be performed for this review.
Stiell 2008
This was a large scale uncontrolled before‐and‐after study which took place across 17 cities in Canada. The study addressed the impact of ALS training for the healthcare personnel who help patients before they reach hospital on patient mortality and morbidity due to injury. The study population included injured patients over 16 years of age with an injury severity score greater than 12. Participants were transported by land ambulance and were treated at one of the 13 leading trauma hospitals in Ontario province. Data on pre‐hospital care were collected from ambulance call reports and the provincial dispatch centre. Individual eligible patients with major trauma seen during the basic life‐support phase (36 months) and the advanced life‐support phase (36 months) were enrolled. The study intervention consisted of standardised national curriculum on advanced life‐support and clinical training period programs. A total of 400 paramedics were trained to perform endotracheal intubation, insert intravenous lines and administer medications and fluids intravenously. The primary outcome was survival to hospital discharge (alive or being transferred to a long‐term care facility) and was obtained from hospital records. Additionally, disease‐specific quality of life in survivors was measured with the 7‐level functional independence measure at discharge and six months. The sample size was determined assuming a minimum absolute difference in the primary outcome of 3.8% between study phases.
A total of 2867 patients were enrolled: 1373 in the BLS phase and 1494 in the ALS phase. There was no substantial difference in overall survival to hospital discharge by phase (81.8% for BLS versus 81.1% for ALS). The only exception to this finding was a lower survival in an 'a priori' sub‐group of cases with an initial Glasgow Coma Scale score of less than nine. This group had lower survival rates in the advanced life‐support phase than in the basic life‐support phase (60.1% versus 51.2%; P = 0.03). There were no differences in morbidity between the phases, as indicated by the Glasgow Outcome Scale and functional independence measure at discharge and six months after discharge. Based on the revised trauma score obtained from the trauma hospital, mortality was non‐significantly increased for patients in the ALS phase (adjusted odds ratio = 1.2), but when the pre‐hospital revised trauma score was used, mortality was worse in the intervention phase (adjusted odds ratio = 1.4, 95% CI 1.0 to 1.9). The presence of ALS providers at the scene and intubation in the field were associated with increased mortality (adjusted OR 1.5, 95% CI 1.1 to 2.0 and adjusted OR 2.8, 95% CI 1.6 to 5.0, respectively). However, total response time was statistically longer in the ALS group than in the BLS group. Univariate analysis revealed that non‐survivors were more likely to be intubated in the field than survivors, and intubations in the field were associated with increased odds of death in multivariate analysis. Based on this, ALS procedures were thought to lead to delays and longer response times which may explain why better trained paramedics have worse outcomes than others.
The characteristics of these studies are included in the Characteristics of included studies table.
Excluded studies
Nine studies were considered for inclusion in the review, but were ineligible as they did not fulfil the study design criteria. A short description of each study is given in the Characteristics of excluded studies table.
Risk of bias in included studies
Arreola‐Risa 2004: Limitations that may have biased the results include having only one control site, testing the intervention in only a few sites, difference in the time frame between groups, and a lack of sample size calculations to evaluate appropriate effect sizes. Because this was not a randomised controlled trial, allocation and blinding could not be done. Thus potential confounders may not have been adequately addressed.
Nicholl 1998: The dispatch of ambulance crews was randomised by opening a sealed, numbered envelope when a potential eligible emergency call was received by the dispatcher. Blinding of outcome assessments was not reported. The poor protocol compliance could have affected the results.
Stiell 2008: The most important limitation of this study was its design as an uncontrolled before‐and‐after study rather than a randomised trial, which is the gold standard to test such an intervention. The authors suggest that since randomised trials are challenging to conduct in the pre‐hospital setting for ethical reasons, the study design was, in this case, the optimal method of answering the study question. Furthermore, sub‐group analyses suggested higher mortality in patients with a lower Glasgow Coma Score although this may be a false positive finding and would need to be evaluated further.
Effects of interventions
All three studies included in this review demonstrated no reduction in mortality for injured patients receiving aid from ALS‐trained ambulance crews versus BLS‐trained crews. The only randomised controlled trial was too small to show the impact of ALS training on injury mortality and morbidity. There may be some evidence to suggest that such training negatively affects mortality in some groups. In Stiell 2008, an 'a priori' sub‐group analysis demonstrated an increase in mortality among patients in the intervention group who had a Glasgow Coma Score less than nine. Additionally, when the pre‐hospital trauma score was taken into account in logistic regression analysis, mortality in the patients receiving care from ALS trained crews increased significantly.
Discussion
Three studies met the inclusion criteria for this review. This is in spite of conducting a very thorough literature search in which a total of 4674 citations have been screened to identify eligible trials. We believe it is unlikely that relevant trials have been overlooked.
Based on the limited data, there is at present no evidence to recommend ALS training of ambulance crews to care for injury victims. This finding highlights the lack of evidence on which current practice and policy in many high‐income countries is based, where pre‐hospital care is often provided by ambulance crews with ALS training. It emphasizes the need to conduct well‐designed intervention studies to establish this effectiveness and inform policy making in trauma services.
The lack of rigorous research may not be easily rectified in settings where ALS‐based services have already been established. There is conviction among the public, the media, and health professionals (including ambulance service staff), that ALS interventions are beneficial in serious trauma. However, despite the practical problems that may be experienced during research, randomised controlled trials remain the most rigorous research design for evaluating health care interventions.
A number of other factors need to be taken into account in planning an evaluative and comparative investigation in pre‐hospital care of injury victims. These include the impact of ALS interventions on scene time, the impact of scene time on outcomes, the mechanism of trauma (blunt versus penetrating), geographical location (distance from hospital care), injury severity, injury pattern (presence and severity of head injury) and mode of pre‐hospital transport. In addition, the configuration of pre‐hospital services needs to be considered. For example, in some countries ambulances are staffed by doctors, many of whom have postgraduate or specialist training in intensive care or anaesthesia, which may affect outcomes. The model of pre‐hospital services, therefore, may be a significant component in future studies and may limit comparability of studies.
Furthermore, training in advanced life support also varies greatly depending on the regional EMS system. While there are some standard certifications (ACLS, PHTLS, etc) many regional EMS systems have their own training programs set up by their medical directors. In addition, requirements for the presence of a certified or advanced life support trained provider at a scene may also differ from region to region. This makes it difficult to compare studies that are conducted in different parts of the world.
Additionally, it is unlikely that a better trained provider provides worse care than a less trained provider as suggested by some studies. Rather, it may be that a better trained provider stays at the scene longer, which then leads to delayed definitive care beyond the so‐called "golden hour" of trauma where it is essential that definitive care is provided as quickly as possible.
Another factor to consider is distance to definitive care. Prehospital providers in more rural locations may benefit more from advanced training so that necessary interventions are not delayed due to travel time. However, in urban settings where distance to a major trauma center is negligible, definitive care can be provided in a more timely fashion when patients are brought to the hospital rapidly by prehospital staff. So skills sets and training may have to be defined and evaluated based on accessibility to major trauma centers.
