In rural Wisconsin, a 14-year-old male sustained multiple burns after throwing a cup of gasoline on a burning brush fire. He was transported to a local community hospital emergency department (ED) and was evaluated by a staff physician. After assessment and initial care, the physician determined the patient had sustained an estimated 20% body surface area (BSA) burn—primarily located on the chest, arms and abdomen. The burn was described as being almost all partial thickness (second-degree).
The transferring physician contacted the University of Wisconsin (UW) Hospital burn center and discussed the case with the attending burn surgeon, who agreed to accept the patient in transfer and advised the referring physician to send the patient by ground ambulance.
The distance from the community hospital to UW is approximately 50 miles (about a 70-minute ambulance ride).
Despite this advice, the referring physician called the communication center at UW Med Flight, based in Madison, Wis., and requested helicopter transport. The flight physician quickly reviewed the case and recommended additional analgesia (he had received only a small dose of morphine) and provided reassurance that the patient could be safely transported to the burn center by ground ambulance.
Approximately 15 minutes later, the flight physician received a call from a regional, community-based, for-profit helicopter EMS (HEMS) operator inquiring about the patient's condition and transfer. The UW flight physician emphasized that both he and the burn surgeon felt that the patient did not require HEMS transport. However, two hours later, the patient arrived at UW by helicopter, transported by another HEMS operator. The patient was evaluated by the burn care team and found to have a 10% BSA burn. He was treated for his minor burns, observed overnight in the burn unit and discharged in the morning. His total hospital bill was $2,900, while his HEMS transport bill was $12,400. His family did not have health insurance.
The Problem
Although HEMS has become an important component of EMS, it's often overused. Most HEMS operators have a "you call, we haul" policy. Few HEMS programs have the desire to limit any flights because increased flight numbers equal increased revenue. Over the past several years, the HEMS industry has slowly transitioned from hospital-based, non-profit services to community-based, for-profit operations. Thus, there's no incentive for most HEMS operators to decrease flights. In fact, there's an obvious financial incentive to increase flight volume.„
But HEMS is not without risk. Between 1980 and 2008, there were 264 HEMS-related fatalities (223 crew members, 34 patients and five others were lost). HEMS should, without question, be considered a medical procedure. As with any medical procedure, it carries potential benefits and risks. In fact, it's the only medical procedure that poses a much greater risk for the provider than it does for the patient. In cases where there's little or no benefit to the patient, any risk is intolerable.„
For some reason, we fail to provide the same risk-benefit analysis of HEMS we would apply to any other medical procedure. For example, if a cardiac catheterization team (cardiologist, nurse or technician) perished along with their patient for every 50,000 cases (the 2007–2008 risk rate associated with HEMS transport), we would hear an immediate outcry for change. First, all efforts would be made to make the procedure safer (technology, practices, safeguards) for the patient and providers. In addition, the utilization of the procedure would be scrutinized to make sure it would be used only when the potential benefits truly outweigh the risks.
Despite significant morbidity and mortality, this strategy hasn't been applied to HEMS. Instead of attempting to limit escalating HEMS usage, many operators continue to focus on increased utilization and expansion into already saturated markets.
Some operators show great resistance to adopting the various safety recommendations promulgated by the National Transportation Safety Board (NTSB).
Ensure Appropriate HEMS Usage
The million-dollar question is: Which patients stand to benefit from HEMS transport and which do not? Generally speaking, the quality of scientific literature either supporting or refuting the benefit of HEMS is limited or of poor quality.
The guidelines for HEMS usage have been generally drawn from trauma triage protocols that are used to ensure patients with significant trauma end up in trauma centers. But just because a patient needs the services of a trauma center doesn't mean they need to go by HEMS. Much of the benefit of trauma center care occurs during the sub-acute and rehabilitation phases of care.
In April 2008, the American College of Emergency Physicians (ACEP) published a policy statement titled "Appropriate Utilization of Air Medical Transport in the Out-of-Hospital Setting." This policy takes a commonsense and evidence-based approach to out-of-hospital HEMS usage, stating, "Appropriate reasons to use an air medical helicopter in the out-of-hospital setting include: Patient has a significant potential to require high-level life support available from an air medical helicopter, which isn't available by ground transport; patient has a significant potential to require a time-critical intervention and an air medical helicopter will deliver the patient to an appropriate facility faster than ground transport; patient is located in a geographically isolated area, which would make ground transport impossible or greatly delayed; or local EMS resources are exceeded."
Patient Requires a Higher Level of Care
In addition to speed, one of the most important benefits of HEMS over ground EMS (GEMS) is quality of care. Some patients require care that can't be provided by standard ground ambulance crews (such as rapid sequence intubation at scene calls). In many cases, especially interfacility transfers, these patients can be transported by ground ambulances using critical care paramedic or critical care nursing crews.„
In a British Columbia study of almost 2,000 interfacility transports of ICU patients, researchers found that HEMS transport wasn't associated with decreased overall mortality when compared to GEMS transport. A University of Wisconsin-Madison study found HEMS interfacility transport to be faster than ground transport, but suggested that stable patients should go by GEMS if timely service is available.„
If the patient doesn't have a time-sensitive condition, consider using ground critical care transport, which is considerably less expensive and safer and provides more workspace in the patient compartment. However, if the patient requires a level of care unavailable by GEMS, HEMS transport should be considered.
Transport Times
HEMS transport is more rapid than GEMS transport. Despite this, at distances shorter than 45 miles or ground transport times less than 30–45 minutes, ground transport is typically faster. In a California study, researchers found GEMS to always be faster at distances shorter than 10 miles. HEMS was found to be faster if simultaneously dispatched with GEMS (which rarely happens). If HEMS wasn't dispatched simultaneously with GEMS (the more common scenario), GEMS was faster at distances shorter than 45 miles.„
An Australasian College of Emergency Physicians policy states that patients less than 30 minutes by road from a hospital don't benefit from HEMS transport. At distances greater than 186 miles (or when HEMS flight time exceeds one hour), fixed-wing air transport is preferred.
Thus, if the patient is more than 45 miles from the hospital, the question becomes whether they have a time-sensitive condition. Here the policy is less clear. Certainly, ST-segment elevated myocardial infarction (STEMI) and stroke patients should be transported by HEMS if it will deliver them to definitive care within an interventional window when GEMS will not.
In trauma, the role is less clear. The reality is, few trauma patients emergently require truly life-saving surgery. In a 10-year study of all trauma patients brought to a Santa Clara, Calif., trauma center, only 1.8% underwent surgery for a life-threatening condition. In another 10-year study, researchers in Los Angeles were unable to identify improved survival for trauma patients transported by HEMS (although they felt severely injured patients might benefit from shorter prehospital times).„
Geographically Isolated Areas
HEMS is an extremely important asset for accessing patients in remote areas or where access is limited. However, very few of the dedicated medical helicopters in the U.S. have the capability of hoist extraction. This is normally delegated to law enforcement or military aviation units. But when GEMS access is limited and HEMS is available, it's often beneficial for a helicopter to respond and transport. HEMS played an extremely important role in the 2005 hurricane disasters on the Gulf Coast.
Local Resources Exceeded
In disasters and similar situations, when GEMS resources can be taxed, HEMS can be a valuable asset. However, using HEMS simply because a local ground service is inadequately staffed or funded, or doesn't want to leave their territory "uncovered," isn't an acceptable solution. For example, let's say an EMS agency has a patient who's sick and needs to go to a hospital an hour away. The patient doesn't require the speed or care HEMS provides, but because the patient is too sick to stay in the community, they're forced to go by HEMS just to keep the local GEMS unit available.
Stated another way, because the patient is sick enough to need care out of the area, they must accept the added cost and risk of HEMS transport solely to keep GEMS available in the service area. However, wouldn't it be cheaper or safer to call for mutual aid or place another ambulance in service? Using a medical helicopter simply to keep ground ambulances available is unethical but common in the U.S. It's tantamount to cost shifting and forces the ill or injured patient to assume unnecessary risks.
Madison Criteria for Patient Exclusion
Few HEMS operations are willing to make a stand and attempt to restrict utilization to only appropriate transports. University of Wisconsin Med Flight is an emergency physician-staffed helicopter service that has made a strong commitment to appropriate HEMS utilization. This is in the interest of both safety and fiscal responsibility to their patients. Their primary focus is on customer (physician and prehospital) education and outreach on these issues, but they will deny service for clearly inappropriate requests. An ongoing program is developing criteria that will hopefully exclude most patients who will not likely benefit from HEMS transport.
The following patient types have some level of evidence against routine HEMS transport.
Burns: Most burn patients will not benefit from HEMS transport unless there's an airway issue or perhaps the need for an emergent escharotomy (a relatively rare surgical procedure to treat circumferential third-degree burns). Airway burns and the need for endotracheal intubation are actually fairly uncommon. Patients with less than 30% BSA (without evidence of inhalation injury) and who are less than 200 miles from the burn center should be transported by GEMS. Trauma patients with burns should be triaged and treated primarily as trauma and routed to a trauma center. Referral to definitive burn care should be secondary. In summary, the vast majority of burn patients should go by ground.
Trauma for mechanism of injury only: For many years, it was dogmatic practice in EMS to send patients to trauma centers, often by HEMS, because of mechanism of injury alone. However, other than ejection from a vehicle, there's no evidence that mechanism of injury criteria alone necessitate HEMS transport (or even trauma-center care for that matter). Australian researchers failed to find that isolated mechanism of injury criteria were clinically significant in predicting serious injury or mortality. The Maryland Institute of EMS Systems now requires physician contact before Maryland EMS providers can use Maryland State Police (MSP) HEMS for patients who meet mechanism of injury criteria (Category C and D patients). Since this policy change, MSP medevacs in Maryland were reduced by more than 50% within a year with no discernible change in morbidity or mortality (although it's still too early to tell for sure).
Neonates: HEMS is widely used for neonatal transport. Despite this common practice, most neonates do well, and HEMS transport doesn't seem to improve outcomes. There's a good argument for using HEMS to rapidly insert neonatal teams into remote hospitals and then transfer the neonate by GEMS once stable. An Ohio HEMS program was able to significantly reduce neonatal transports by instituting a neonatal HEMS transport policy. Specialty teams traditionally have prolonged ground times. The one-way team transports also increase aircraft availability for other flights.
Obstetrics: Little evidence affirms the role of HEMS for obstetrical transport. The vast majority of obstetrical interfacility transports are uneventful. A Texas study found no differences in outcomes between patients transported by HEMS and those transported by ground (with the exception of tenfold higher transportation costs for the HEMS patients). Further, in the rare event of a precipitous delivery, the limited space of most medical helicopter interiors would be an obvious drawback.„
Orthopedics: Isolated orthopedic injuries, with the exception of vascular or neurologic compromise and certain pelvic injuries, are generally not life-threatening and don't require emergent operative intervention. HEMS transfer for traumatic amputations (considered for replantation) should take place only after consultation with an appropriate receiving surgeon. Most isolated orthopedic injuries can go by GEMS.
Spinal injuries:No evidence shows that patients with spinal injuries benefit from HEMS transport. Unless accompanied by other significant trauma or progressing neurologic deficits, most patients with suspected or diagnosed spinal injuries can be safely transported by GEMS.
Cardiac arrest:No evidence proves that HEMS transport of patients in cardiac arrest at the time of request, either medical or traumatic, is useful or should be used.
Interfacility transfers: Virtually all studies of HEMS interfacility transport fail to demonstrate a significant advantage over GEMS transport. A Missouri study of medical and trauma interfacility transports failed to show any difference in 30-day survival, disability, health status or health-care utilization.
A similar study found no outcome advantage for HEMS interfacility transport of cardiac patients. Overall, the indication for interfacility HEMS use is the same as for scene HEMS use. That is, does the patient have a time-critical condition from which HEMS would get the patient to a definitive care facility within the interventional window when GEMS would not? If yes, consider HEMS. If not, use GEMS. Or, does the patient require a level of care unavailable by GEMS (including ground-based critical care transport)? If yes, use HEMS. If not, use GEMS.
Summary
Additional research is absolutely required on this important issue. Some current guidelines which can assist us in ensuring appropriate HEMS usage. This strategy, detailed in Figure 1 (p. 85), is based on the ACEP policy discussed earlier. Determining whether a patient has a time-critical condition is more difficult. Figure 2 (p. 86) details the decision scheme for determining whether a patient has a time-critical condition that will benefit from HEMS transport. Regardless, always err on the side of caution. If you're uncertain, offer the patient HEMS transport or consult with your medical director.
Medicine and EMS are all about weighing benefit and risk. Our patients don't always understand these at the time of care and rely on us to make decisions in their best interest. HEMS is a medical procedure that should be critically evaluated before and after usage.
We need to ensure that patients who will benefit from HEMS transport are offered HEMS transport. To achieve this, some patients will be transported by HEMS who will ultimately not have benefited from the transport (overtriage). Some small degree of overtriage is acceptable. More importantly, we don't want to exclude patients from HEMS transport who would benefit (under-triage).
Calling the helicopter should not be a reflexive action. It should never be used for the "convenience" of the EMS crew, referring physician or the patient. As with any complicated medical procedure, some thought and reasoning have to be put into the circumstances before subjecting your patient to any risk. As research evolves, the usage guidelines will be revised and we'll be able to better identify which patients will benefit from HEMS transport (and those who don't.) JEMS
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