Delivering care via Helicopter Emergency Medical Services (HEMS) is a task that cannot be underestimated. The correct intervention, at the right time in patient care is a key element not only to survival, but to overall patient rehabilitation. So what factors are considered before dispatching what can be considered a scarce resource to the correct call – one that requires advanced clinical intervention beyond the scope of regular ambulance crews? With no standardized method used by HEMS providers in the UK, what drives the use of helicopters, and what can we learn from other providers across the world?

HEMS protocols

The need for a HEMS response is one born from an acute medical situation and emergency, which is time critical and can make an impact upon patient management. One approach which is common in the UK and internationally is a ‘HEMS desk’, where a HEMS-trained paramedic screens incoming calls to assess when HEMS intervention is appropriate. However, with a lack of standardization in dispatch, and individual clinical judgement being called into play to task a HEMS response, this presents limitations.

The need for a HEMS response is one born from an acute medical situation

Babcock International currently partners with nine UK-based HEMS service charities. Lorena Rodrigo, the company’s Director of Comms Aviation kindly shared with AirMed&Rescue: “The HEMS desk teams have a responsibility for the identification of a HEMS suitable event from the 999 emergency calls received by the ambulance service event stack. Communication and liaison with other agencies in relation to HEMS matters is of paramount importance.”

Below is the dispatch criteria for one of their customers:

Immediate dispatch:

Immediate dispatch criteria are those where the type of incident indicates a high probability that the patient will benefit from having enhanced care. Examples include:

• Fall from greater than two storeys (approximately 20ft)
• Ejection from a vehicle
• Amputation of a limb above the wrist or ankle
• Individual trapped under a vehicle (excluding motorcycles)
• Confirmed paediatric cardiac arrests
• Confirmed aircraft accidents
• Stabbing to the chest
• Request from other emergency services (e.g. RNLI via Coastguard).

Interrogated dispatch:

Interrogated calls are where the HEMS Desk Clinician has either listened in to a call or managed through a set

procedure to talk and question the 999 caller. Examples include:

• Major/significant incident, confirmed or on standby
• Shooting (including confirmed or suspected active shooter incidents
• Stabbings
• Explosions
• Road traffic collisions
• Industrial accidents or incidents
• Fires
• Drowning
• Entrapment
• Amputations
• Burns or scalds
• Industrial site accidents
• Falls from heights of less than two storeys (20ft)
• Impalation on object
• Adult cardiac arrest - where back-up is required or requested by on-scene resources
• Fainting
• Individuals falling or jumping in front of train
• Falls from horse
• Obstetric emergencies involving trauma or imminent pre-term birth.

Other types of intervention for HEMS mobilization are:

Primary interventions: The specialized helicopter medical team intervenes either in the field as close as possible to the patient, or as backup to another HEMS team already on site.

Crew Request: A crew request is where a crew or qualified responder has requested HEMS support to an incident

Inter-hospital transfer: The patient is transferred to another hospital for more specialized care within the framework of predefined care channels. The emergency and seriousness criteria make it possible to distinguish this mission from a simple medical transport between two establishments. These can either be carried out as a HEMS mission or an Air Ambulance mission depending on the condition of the patient and the timescale involved.

Dispatching in New South Wales

When we look at how HEMS providers operate around the world, it becomes clear that trauma is not only the type of emergency that can trigger dispatches – in topography such as New South Wales (NSW), Australia, remoteness is also a factor.

At the NSW Ambulance Aeromedical Control Centre (ACC), the prehospital dispatch team are known as Rapid Launch Trauma Coordinators (RLTC) - paramedics who have trained as ACC officers, and subsequently undergone further training to be RLTC. 

“The jobs they search for are primarily trauma based but will send to severe medical event (e.g. pediatric cardiac arrest or near arrest) or other events where remoteness from appropriate care or likely need for prolonged high level prehospital care may be involved,” said Dr Neil Ballard Co-Director, Aeromedical Clinical Operations at NSW Ambulance. “We recently sent a medical team to a 300kg patient who was unconscious likely due sepsis with a prolonged extrication from an apartment building in inner Sydney.”

With eight helicopter bases across the state, seven of these are equipped to respond by road or air, with the Sydney base reserving one its three helicopters for neonatal/pediatric interhospital missions.

Dr Ballard continues: “The ACC also uses a program called iTRACC which gives response times by helicopter and road from various bases to the latitude and longitude of a scene. The flight times have been precalculated, and the drive times link to google maps to consider traffic conditions, roadwork, et cetera. An estimate is applied to the drive time for blue light driving - this will vary for country versus city roads. There are some jobs where distance isn't a factor such as remote access missions requiring winch insertion and recovery, and these are always done by helicopter.”

It is clear that this is a complex process, handled by experienced clinicians along the way but surely a more defined protocol would be simpler? Dr Ballard counters this, “We do not have a protocol for determining road versus air tasking to a prehospital mission. We spent some time trying to develop one for the Sydney base, but it was clear that there were so many variables to take into account (distance to scene, time of day, traffic, aviation planning) that for those jobs where it is not immediately apparent which asset to use, the best approach is an immediate huddle around the ‘batphone’ when a job is notified.

“Our process of notification of prehospital jobs between 07:00 hr and 22:00 hr is to ring the ‘batphone’ on base, and all crew on-base respond immediately to the ready room. A quick discussion ensues by speaker phone between the RLTC and whichever CCP gets to the phone,” he added.

With over 41 years in operation, evolution has been essential for NSW Ambulance, and protocol reviews are continual, shared Ballard, “We undergo a system of continuous review. Our most recent change was instituting an 'RLTC alert line' so that any clinician on one of the helicopter bases can alert the RLTC to a job that may have been missed (this happens occasionally when multiple jobs happen at the same time). We have Computer Aided Dispatch (CAD) on-line at all time on all bases - primarily so crews can get detailed information on a job once tasked. But many of us screen it during the day - therefore, if a potential job is noticed and there has been no dispatch within five minutes of first keystroke, you can ring to notify the RLTC of the job.

“Pursuing further information (if required) and making the decision to task remains the responsibility of the RLTC. Going forward we are hoping to get a version of CAD that would highlight to the RLTC some keywords that might warn of the possible need for a medical team, e.g. 'gunshot' 'stabbing' 'trapped' on top of the categories already given on CAD e.g. MVA, MVA trapped, extreme fall. With up to 5000 jobs/day on CAD (rolling average 3500) across NSW there is certainly scope for improved job identification,” he added.

Adverse weather conditions

Most providers will agree that the prime objective is to reach the patient at the first attempt, but another consideration in deciding between ground versus air attendance is adverse weather.

Richard de Coverly, Assistant Director of Service Delivery at Air Ambulance Charity Kent Surrey Sussex (KSS) agrees, “Our primary aim is to reach the patient on the first attempt, rather than deploying the aircraft in the first instance, only to have to turn around and return to base because of poor weather, and then proceed by land. This causes delays, and can affect decisions made by the ambulance team on scene who are caring for the patient before our arrival.”

Our primary aim is to reach the patient on the first attempt

KSS HEMS dispatchers do however have a set of guidelines set against three main components: mechanism, condition, and location, mirroring the protocols of other UK HEMS providers.

For incidents meeting immediate dispatch criteria, only one trigger is required to be detected from an emergency call to trigger a dispatch. For interrogated dispatch, two triggers are required, and these are designed to capture the less well-described situations where there is the potential for major trauma, but there may be delays. They also receive requests from their co-located Critical Care Desk, who are dispatching the ground based Critical Care Paramedics, and also receive ambulance crew requests for support on scene.

“The dispatch criteria and the wider operational deployment plan are reviewed annually as part of our scheduled review of policies and standard operating procedures,” said de Coverly. “They are amended based on trends identified and feedback from the core dispatch team. The most recent amendment did not change the services activity, but activity is growing as a result of increased demand throughout the healthcare system. It is likely that the next amendment will have a few additional dispatch triggers which will be driven by changes and updates to the Major Trauma decision tool in use.”

“Some of the dispatch criteria for KSS HEMS are very much ‘pattern recognition’ and driven through a set of dispatch triggers. However, some of the situations encountered by the dispatch team are so rare or unexpected that there cannot be a dispatch definition for every eventuality. In these situations, call interrogation and human decision making is required,” he added.

Communication is key between the emergency services, and it is clear that the real success is when ground and HEMS crews work together. Although HEMS do not have the monopoly on sick patients, what they are able to accomplish is adding meaningful intervention to situations where it is needed. Identifying that need is a complex process at risk of over triage and high stand down rates which is tolerated because the alternative of criteria for dispatch being too stringent equals missed care or later intervention and rehabilitation for the patient, which is far less tolerable.