Review of: Bulger E, Guffey D, Guyette F, et al. Impact of prehospital mode of transport after severe injury: A multicenter evaluation from the Resuscitation Outcomes Consortium. J Trauma Acute Care Surg. 2012;72(2):567—575.
The Science
This study is a retrospective analysis of prospectively collected data from the Resuscitation Outcomes Consortium on the survival of patients with hypovolemic shock and/or a traumatic brain injury (TBI), comparing their mode of transport: ground vs. helicopter. More than 2,000 patients qualified for the study, with approximately 700 patients being transported by helicopter. The investigators found the patients that were transported by helicopter tended to be more seriously injured and many suffered from blunt force trauma. Survival was analyzed at 28 days and 6 months in both groups; however, six-month follow up was reserved for patients with TBI. The analysis of the data showed no statistical difference in survival between the modes of transport in either the hypovolemic shock group or the TBI group. The only conclusion was that helicopter mode of transport was associated with longer prehospital times, more advanced life support procedures and more severely injured patients.
Dr. Wesley: The role and clinical impact of helicopter EMS (HEMS) transport for trauma patients competes closely with prehospital intubation as one of the most controversial topics in emergency medical care. There have been more than a half dozen papers published on the issue during this past year, and each provides a slightly different answer.
Some say a great survival benefit exists while others, like this one, say there is none at all. Most of them qualify their answer with “sometimes” or “in selected cases.”
What did these authors add to the discussion? One must read the paper in detail to determine its merits. I suspect they have created more confusion than solutions; this was not a straightforward analysis of HEMS. Instead, it was an analysis of data collected from a multicenter trial examining the role of hypertonic saline administration for trauma patients. This group of patients may not be reflective of the typical prehospital trauma patient. When they examined this study population, they discovered that those transported by HEMS were more significantly injured and more likely to receive intubation.
Additionally, to qualify as study patients, they had to be cared for by ALS because this was an evaluation of prehospital fluid administration. Several studies have shown that HEMS improves survival when ground ALS transport isn’t available. And finally, this study population wasn’t homogeneous. There was significant variation in the frequency of HEMS use–with one service using it in less than 10% and another using it for more than 90% of trauma patients.
The single most important conclusion the authors present in their discussion is that the clinical value of HEMS may be more related to geography and local resources than anything else. HEMS has its value, and I doubt that any single paper will answer the question definitively. Just like intubation, its value is based on local resources, use and medical oversight.
Medic Marshall: Like the Doc said, HEMS is truly one of the most controversial issues in EMS today not only from the clinical aspect, but also in regards to safety itself. It almost seems like every few months a news article or clip comes out that highlights yet another medical helicopter crash that kills everyone on board.
So, you’re an ALS provider who works on an ambulance. You’re reading this study and asking yourself, “Am I just better off transporting these patients myself?” Well, the answer is: it depends. I’m reminded of a conversation I recently had with a prominent EMS figure about whether there’s one right way to deliver EMS care.
The conclusion of that exchange of thoughts and ideas was: EMS needs to be tailored to your community’s needs. In some communities, HEMS may be the best mode of transportation for critically ill or injured patients, e.g., some very remote rural community two hours from the nearest trauma center. However, HEMS may not be very applicable to urban areas, where even in heavy traffic areas, ambulances can get to a trauma center within 20 minutes at the most. It all depends on your community’s needs.
I don’t think the goal of this study was to deliver a definitive answer on the benefits of HEMS, nor was it to try and show the consequences of it. If anything, it demonstrates the vast variability of its use–and I’m not entirely sure that the use of HEMS is directly a result of the geographic areas in which they’re heavily deployed (or rarely deployed, for that matter).
Perhaps a better study would be to examine what types of communities benefit from the use of HEMS, instead of focusing the studies on illness or injury. Once we understand this concept, HEMS can be more strategically deployed and utilized, which would ultimately lead to increased outcomes while simultaneously decreasing costs (and hopefully risks).
Abstract
Background: There is ongoing controversy about the relative effectiveness of air medical versus ground transportation for severely injured patients. In some systems, air medical crews may provide a higher level of care but may require longer transport times. We sought to evaluate the impact of mode of transport on outcome based on analysis of data from two randomized trials of prehospital hypertonic resuscitation.
Methods: Injured patients were enrolled based on prehospital evidence of hypovolemic shock (systolic blood pressure <70 mm Hg or systolic blood pressure =71—90 mm Hg with heart rate >108 bpm) or severe traumatic brain injury (TBI; Glasgow Coma Scale score <8). Patient demographics, injury severity, and physiology were compared based on mode of transport. Multivariate logistic regression was used to determine the impact of mode of transport on 24-hour and 28-day survival for all patients and 6-month extended Glasgow Outcome Scale for patients with TBI, adjusting for differences in injury severity.
Results: Included were 2,049 patients, of which 703 (34%) were transported by air. Patients transported by air were more severely injured (mean Injury Severity Score, 30.3 vs. 22.8; p <0.001), more likely to be in the TBI cohort (70% vs. 55.4%; p < 0.001), and more likely blunt mechanism (94.0% vs. 78.1%; p _<0.001). Patients transported by air had higher rates of prehospital intubation (81% vs. 36%; p < 0.001), received more intravenous fluids (mean 1.3 L vs. 0.8 L; p < 0.001), and had longer prehospital times (mean 76.1 minutes vs. 43.5 minutes; p <0.001). Adjusted analysis revealed no significant impact of mode of transport on survival or 6-month neurologic outcome (air transport–28-day survival: odds ratio, 1.11; 95% confidence interval, 0.82—1.51; 6-month extended Glasgow Outcome Scale score <4: odds ratio, 0.94; 95% confidence interval, 0.68 —1.31).
Conclusion: There was no difference in the adjusted clinical outcome according to mode of transport. However, air medical transported more severely injured patients with more advanced life support procedures and longer prehospital time.
