Aeromed pros disagree over efficacy of EMS

 - May 6, 2008, 6:17 AM

Nearly since the first U.S.-based emergency medical services (EMS) flight operation was performed in the early 1970s, controversy has swirled around the practice. In battlefield conditions, where the dangers were more clear cut and the issue nearly always one of life and death, questions on the efficacy and cost-effectiveness of EMS flights are rarely raised.

On the home front, however, the story is altogether different. Almost since the first day Dr. Malcolm Cowley, the father of the modern helo-based EMS concept, began conducting his first airborne operations from the University of Maryland’s Baltimore shock/trauma center, controversy over the risks and benefits of aero EMS operations has raged. The practice has come under fire from insurers anxious to cut costs. Severe upticks in the EMS accident rate have also drawn fire from critics.

In late June, Texas-based civil and aeronautical litigation lawyer Michael Slack published a paper, Air Ambulance Operations: Enhancing Public Safety or Causing Unnecessary Tragedy?, in which Slack takes many of the concepts underlying the aeromed industry to task. As presented, Slack’s arguments and assertions are compelling, sometimes even alarming. To put them into what we hope is a proper perspective, we decided to submit his paper for comment to the leading aero EMS organization, the Association of Air Medical Services (AAMS). A representative group of its members reviewed Slack’s paper and offered their response. Like Slack’s paper, the AAMS report was forceful, often fascinating reading.

Space considerations within AIN preclude a full-text, side-by-side publication of both papers. In its place, we present this condensed version in a point/counterpoint format. Our intention is not to prove one side right or the other wrong, but instead to present an informed exchange of views between industry professionals.

Accident Rates

Slack: Since 1972 helicopter EMS programs have dramatically increased in number worldwide. By 1987 there were 155 commercial emergency helicopter ME programs in the U.S., increasing from 42 programs in 1981. By 1995 there were an estimated 300 helicopter EMS (HEMS) programs operating in the U.S.

From 1980 to 1986, the HEMS accident rate was an astonishing 13.42 per 100,000 flight hours. Stansbury states in his article (“Turbulent Times Persist for Air Medical Transport,” Journal of Emergency Medical Services, issue 52, 1996) that “the storm peaked in 1986 with 14 helicopter and three airplane accidents that left 13 people dead.” In retrospect, the storm may have merely abated for a few years. The storm appears to have returned with a vengeance in the mid-1990s, accounting for 13 deaths in 1998, 10 in 1999 and 11 in 2000.

: While the author notes an increase in the number of accidents from 1998 to 2000, as compared with the early to mid-1990s, he provides no corresponding data to understand those accidents in relationship to exposure…the major EMS helicopter operators in the U.S. reported a 12-percent increase in flight hours between 1998 and 1999 alone. Thus, the absolute accident rate must be tied to the exposure rate to make any definitive conclusion about the safety of flight operations. The data, normalized over time, indicates that medical helicopter accident rates per 100,000 flight hours are lower than those of all helicopter operations, general aviation and scheduled Part 135 operations (A Safety Review and Risk Assessment in Air Medical Transport, University of Chicago Safety Committee [2002]). This is in spite of the increased hazards of unscheduled EMS operations, often at night and using scene-landing zones.

Averaged over the past five years, medical helicopter accident rates of 3.45/100,000 flight hours are significantly lower than the mid-1980s rates (13.42/100,000 flight hours) cited by the author. This is not to suggest there is an acceptable rate of accidents. The goal is and must be a zero-accident rate. Without question, more needs to be done to ensure safety of our air operations, but clearly lessons have been learned.

Does Aero EMS Save Lives?

Slack: In the realm of trauma injuries, several studies have concluded that HEMS has very limited medical value to the vast majority of patients transported. A retrospective 3.5-year study of trauma patients transported by helicopter and ground ambulance, 62 percent of whom had sustained major trauma, demonstrated that patients transported by helicopter did not enjoy a statistically significant improvement over those transported by ground (P.A. Cameron, “Helicopter Retrieval of Primary Trauma Patients by a Paramedic Helicopter Service,” Australian and New Zealand Journal of Surgery, 790, 796, [1993]). Another study that assessed the response time of helicopter and ground ambulances concluded that activation times, response times and on-scene times for helicopter transports were longer, on average, than ground ambulances in the service area analyzed (J.P. Nichol, “A Comparison of Costs and Performance of an Emergency Helicopter and Land Ambulances in a rural Area,” Injury [1994]). The same study also concluded that prevailing triage practices resulted in an overuse of helicopters in approximately 85 percent of transports (Matthew L. Moront, “Helicopter Transport of Injured Children: System Effectiveness and Triage Criteria,” Journal of Pediatric Surgery [1996]).

Another study (Paul Cunningham, “A Comparison of the Association of Helicopter and Ground Ambulance Transport with the Outcome of Injury in Trauma Patients Transported from the Scene,” Journal of Trauma [1997]) analyzed trauma data compiled for patients transported by helicopter and ground ambulance. The expected outcomes for patients transported by helicopter were no better than for those transported by ground, except among a small subset of seriously injured patients. When analyzed for mortality rates, there were no significant differences between the two groups of patients. The beneficial effects of helicopter transfer were statistically better in only the minority of seriously injured patients.

This study, which involved a large patient population and covered a five-year period, emphasized the need to better identify patients who would benefit medically from this expensive and risky mode of transport. Most recently, the 1999 Brooke Army Medical Center study of 792 trauma patients transported by helicopter and ground ambulance concluded that there was no statistically significant difference between mortality rates for either group when compared with national mortality rates.

AAMS: To begin, the Brooke Army Medical Center study found that “HEMS patients were of a significantly higher acuity [meaning they were in better overall health despite their illness or injury] and that only in HEMS evacuations of the most severely injured from those points farthest from the trauma center did mortality rates meet national averages for ground-based transport.” This is a case for rather than against the use of medical helicopters for critically injured patients.

The question of outcome benefits associated with air-medical response and transport is quite complex. It is not enough to locate and quote various studies. It is also necessary to evaluate the studies for methodology and accuracy of conclusion. We believe the evidence relates a very different picture.

Does the deployment of specialty medical teams in helicopters save lives? Yes, and it especially does so when the helicopters are effectively deployed in and near where people are likely to be injured or ill. The integration of air-medical transport with sophisticated trauma care systems in the U.S. has dramatically decreased the morbidity and mortality of the critically injured. Numerous studies have shown that trauma center care is effective in improving outcomes, but without an effective way of delivering the patient to the trauma center mortality increases (Committee on Injury Prevention and Control, “Reducing the Burden of Injury: Advancing Prevention and Treatment,” Trauma Care [1998]).

Air-medical transport is not a goal in itself, but a tool to rapidly deliver advanced medical care to the patient and to decrease out-of-hospital time.

Trauma care has improved dramatically over the past several decades. Just to cite one of the earliest comparative studies, researchers William Baxt and Peggy Moody “The Impact of a Rotorcraft Aeromedical Transport Emergency Care Service on Trauma Mortality,” Journal of the American Medical Association, June 10, 1983) traced the mortality of 150 consecutive trauma patients transported to a San Diego hospital by conventional prehospital emergency medical transport against another 150 consecutive trauma cases transported to the same facility by air ambulance. A statistical analysis designed to predict mortality based on injury severity revealed that the mortality of this San Diego group was no different from that of a large number of trauma patients treated at another major trauma center. There was, however, a 52-percent reduction in predicted mortality among the air-medical group. This reduction in mortality was attributed to the ability of a helicopter to deliver a highly skilled medical crew to the patient and communicate effectively with the hospital.

A survey of recent research notes a 2- to 12-percent increase in unexpected survivors–patients whose lives are saved through the use of helicopter medical teams for critical patients (“Cost Effectiveness Analysis Of Helicopter EMS For Trauma Patients,” American Emergency Medicine [1997]; Vermont Helicopter Review Committee Report, Vermont Health Authority[1998]; “The Impact of a Helicopter Emergency Medical Services Program on Morbidity and Mortality,” American Medical Journal [1997]).

A more recent study reports the reduction in mortality to be as high as 24 percent (“Helicopter Transport and Blunt Trauma Mortality,” Journal of Trauma [2002]).