End tidal carbon dioxide monitoring in prehospital and retrieval medicine: a review

End tidal carbon dioxide (ETCO2) monitoring is the noninvasive measurement of exhaled CO2. The Intensive Care Society guidelines include (ETCO2) monitoring as one of the objective standards required for monitoring patients in transport, and the American Heart Association recommends that all intubations must be confirmed by some form of ETCO2 measurement. The physiological principles and technology underlying ETCO2 measurement and the clinical indication for its use in the prehospital environment are reviewed. ETCO2 monitoring has been widely established in the prehospital environment and is of particular use for verification of endotracheal tube placement. It is non-invasive and easy to apply to breathing circuits. The units now available are compact and rugged, with extended battery operating times, which are ideally suited for prehospital use and should be considered as an essential item for advanced airway management.