Pre-hospital scene times

The current iteration of the Auckland HEMS is not the first version. For a period of time in the 1990s ARHT had registrars attached to the service (mainly Emergency Medicine trainees). Following a period of operational work, the perception within both ARHT and external organisations like St Johns Ambulance seemed to be that the presence of doctors often prolonged scene times and was not beneficial to the patient. (note – if anyone wishes to refute/expand/explain this further  – please do so in the comments section below, your input is welcome!) The perception that the relatively junior doctors prolonged scene time is in keeping with the literature, as demonstrated in this study from Germany, which showed that junior ED doctors had pre-hospital scene times that were 6.3 minutes longer than their senior colleagues.

With this historical issue, scene time has been (and remains) a significant issue for the current Auckland HEMS. It is closely monitored by ARHT and external agencies, and we have already received correspondence regarding our scene times on some missions. Auckland HEMS in its current iteration involves more senior doctors – mostly vocationally-registered specialists or very senior registrars, who (in theory!) should be more capable of rapid assessment and management.

My own observation from operational work is that as scene time extends, there is a rising sense of anxiety among the team about scene time (myself included) that may pose a risk in itself, and lead to transporting incompletely assessed/managed patients purely because the scene time is getting “too long”.

So what is the effect of scene time on the patient?

In the setting of trauma, somewhat surprisingly, the evidence does not suggest that at a population level prolonged scene times are associated with worsened outcomes. A retrospective cohort study of over 3000 significantly unwell trauma patients found that there was no association between mortality and any pre-hospital interval, including activation, on-scene time, transport time, or total pre-hospital time. This finding goes against the traditional concept of the “Golden Hour” during which patients must be brought to hospital to give them the best chance of survival. A similar study of trauma patients from 2003 found that age, injury score, and perceived clinical status were related to mortality, but total pre-hospital time was not.

Clearly there is a subgroup of trauma patients who have a time critical problem (uncontrollable haemorrhage, extradural haematoma etc) just as there are medical patients with time critical problems (STEMI, for example) and the onus is on the HEMS team to identify these patients at the scene and favour rapid transport over intervention at the scene. Even in this setting however, it is worth noting that time to hospital is not necessarily the same as time to definitive intervention, and that sometimes a few extra minutes at the scene could have significant time savings downstream. Examples of this would include taking a few extra minutes to contact an interventional cardiologist to activate a cardiac cath lab, or performing FAST scans at a scene with multiple trauma patients to triage them for air versus road transport.

So how does this all this impact on us as doctors and team members in the pre-hospital setting?

1) We need to move on from the “scoop and run” versus “stay and play paradigms

This debate is (in my humble opinion!) irrelevant. Prehospital scenes and clinical issues are not homogenous, and there is no ‘one size fits all’ paradigm that can be applied to pre-hospital care. The whole point of the current HEMS structure, which combines paramedic, doctor, crewman, and pilot expertise is to enable the team to use their combined expertise to deliver a package of care that is individually tailored to the patient. In some cases, a ‘scoop and run’ will result, in other cases advanced interventions are required urgently, and the result is ‘stay and play’. If a patient needs urgent intervention, they should recieve it from a qualified person as soon as possible, regardless of the location. As Cliff Reid states in this podcast, “the pathophysiology doesn’t care where the patient is”.

2) We must communicate decisions regarding scene time to the whole team

As well as the HEMS team having a “shared mental model” of what needs to happen at the scene, we must consider the first responders also. Our St John’s Ambulance colleagues work hard to assess, manage, and transport their patients as quickly as possible. It must be incredibly frustrating for them to have the HEMS team arrive and then feel that the scene time is being prolonged without good reason and a sense of urgency is lost. If a decision is made by the HEMS team to further treat/stabilise a patient prior to transfer (for example giving a patient with severe asthma 20 minutes of aggressive inhaled and intravenous therapy plus PEEP prior to a decision about intubation for aeromedical transport), this decision, and the reason for it, must be clearly communicated to the first responders. If we don’t do this, we run the risk of alienating our colleagues who are in a position to help both at the scene and on future operations.

3) We cannot let concern over scene times override clinical judgement

Clearly for time-critical conditions a short scene time is important, and there are significant operational concerns as well regarding prolonged scene times (time away from base affecting training and maintenance, approaching poor weather/night etc), but we must put aside the idea that prolonged scene times are inherently bad in ALL cases. Placing concerns over scene times ahead of interventions that our patients need urgently puts them at risk.

4) The key to shorter scene times is efficiency through training

We must ensure that all of the time we spend at a scene, especially if we make decisions that prolong scene time, is time that adds value to the patient’s care. This requires efficiency of communication amongst our team, efficiency of procedures, efficiency of equipment, and efficiency of “packaging” for transport.

Full text pdfs for this post are available here (secure area limited to ADHB staff only – ADHB has subscription access for staff to these journals through the Philson Library at the University of Auckland School Of Medicine)