Early Warning Scores for Critically Unwell Patients in Remote Setting
Working in remote environments, whether on an expedition, a media production or a healthcare setting in a resource poor environment can be rewarding, fulfilling and challenging in equal parts. Of the challenges posed to the clinician by the nature of this work, distance (and ultimately time) from ‘definitive medical care’ may represent the greatest threat to the members of your team (Renouf and Pollard, 2016). Dealing with acutely unwell patients has added complications due to resource limitations, environmental conditions and evacuation times. The remote clinician may therefore be required to make early clinical as well as logistical decisions in order to manifest the best outcomes for their patient (Imray et al., 2015., Duchatau et al. 2009).
‘Early Warning Scores’ (EWS) have been developed for both in-hospital as well as pre-hospital use in order to identify acutely unwell patients, to ensure rapid and efficient clinical responses, and to optimise patient outcomes (NICE, 2020, Medina-Lozano et al., 2020). These systems benefit patient care by creating a standardised score of illness severity, thereby allowing consistent decision making and clinical responses (Downey et al., 2017).
Also known as ‘Track and Trigger’ scores, these systems look at a range of physiological parameters and score them based on their relative derangement from the norm. They allow for the tracking of patient recovery or deterioration, and can trigger clinical interventions and evacuation.
The ‘NEWS2’ score has been used in the UK both in hospital and prehospitally since its introduction in 2017. It is becoming widely used globally, and its accuracy in identifying critically unwell patients in the prehospital setting is widely supported in the literature (Martín-Rodríguez et al., 2019, 2020, Shaw et al., 2017). The system uses six physiological parameters as shown in figure 1.
Fig.1 NEWS2 Early Warning System
The patient’s aggregate score can trigger responses (as can individual parameters with significant derangement) and the score can be monitored over time to assess any improvement or deterioration. This can be particularly useful for the clinician caring for teammates in the field, making evacuation decisions and extracting casualties.
The physiological parameters are generally easily recorded, with lightweight portable equipment (Fig. 2).
Fig. 2 Small observation kit for use by medic on the move
There may be difficulties in attaining certain parameters in some situations. Notably achieving a reliable core body temperature in trauma patients using either a sublingual or tympanic thermometer is likely to be unrealistic (Keene et al., 2017., Skaiaa et al., 2015). The option to use the Swiss Staging model (fig. 3) for predicting severity of hypothermia exists for certain cold stressed patients (Haverkamp et al., 2020., Pasquier et al., 2019) but a reliable core temperature should be achieved as soon as possible (Karlsen et al., 2013., Gerecht et al, 2014).
Fig 3. Swiss Staging Model for Hypothermia
Another difficulty with the system is the potential inability to deliver oxygen in a remote setting. In some situations, this may correlate to low oxygen saturations, thereby triggering the system. There may also be times, for example major trauma in a patient with adequate saturations, where the clinician is required to take a judgement on whether they ‘would’ apply oxygen if it were available, and score the patient accordingly.
There exist other EWS systems in use which may be equally useful to the remote area medic. The Modified Early Warning System (MEWS), Search Out Severity (SOS) and the quick Sequential Organ Failure Assessment (qSOFA) are all relevant and the remote clinician may need to select the appropriate tool depending on the specific situation, patient and local medical facility.
These EWS systems could be used by the remote clinician to support their interventions and in the often complex decision making processes around evacuation criteria.
References
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