Prehospital capnography or capnometry: are we going in the right direction?

Abstract

End tidal carbon dioxide (etCO2) measurements enable accurate monitoring of airway patency, ventilation (self or assisted) and metabolism. It is mandatory in current in-hospital anaesthetic practice and now recommended in the prehospital setting. Traditional methods of capnography have used either mainstream or sidestream devices, but both are not without their disadvantages, which may be potentiated in the prehospital environment. Portable devices either display a waveform (capnography) or a numerical reading alone (capnometry). Waveform capnography is often the preferred mode of CO2 detection in prehospital practice (mirroring experiences from in-hospital), however, there is no published evidence comparing the superiority of either method. The most recent advancement in prehospital capnometry is the introduction of a compact, light-weight, battery powered, self-contained mainstream capnometer. This device has been shown to be accurate when compared with anaesthetic equipment and appears to meet all the qualities required for inclusion as a tool for the improved care of the prehospital patient. It displays only a numerical reading as opposed to some new defibrillators used by certain ambulance services which include waveform capnography. The authors feel this difference would have very little detrimental effect on patient management out-of-hospital. This, coupled with the advantages gained by greater access to etCO2 monitoring, related to both cost and training, considerations have enabled the conclusion that this type of mainstream capnometer should be considered more often for prehospital care.