Arterial blood gas and electrolyte measurement on air ambulances
Abstract
Arterial blood gas and electrolyte analyses are routinely conducted for critically unwell patients in the hospital setting. Modern and portable point-of care analysers now allow these tests to be performed in the pre-hospital setting. A small number of studies have looked at the potential for performing these tests in the prehospital setting and identified that on-scene testing can alter management of these critical patients.
Aims
To look at the feasibility of introducing a point-of-care arterial blood gas and electrolyte analyser onto a medically-led air ambulance service.
Methods
A retrospective review of the mission data for Warwickshire and Northamptonshire Air Ambulance (WNAA) for all missions between 1st January 2007 and 31st December 2007 was conducted. Patients who could potentially benefit from pointof- care analysis were identified. The physical properties of the i-STAT machine were analysed, specifically the operating temperature range. Air ambulance crew members were asked for their opinions on the potential of point-of-care analysers.
Results
The i-STAT machine could potentially have been used in 174 out of 414 patients (42%) transferred by the air ambulance. The most common indication for use would have been head-injured patients. The operating temperature range of the point-of-care analyser (16–30°C) and the associated temperature drop when the aircraft is flying at 1000 feet means that the machine would only be functional between June and late August (assuming normal seasonal maximum temperatures). Crew members felt that due to the short flight time for primary transfer to hospital, the impact on patient outcome would not be significant for the majority of patients.
Conclusions
The benefit of performing point-of-care analysis on air ambulance patients remains uncertain. The operating temperature range will also limit the i-STAT machine use on air ambulances.