• J P Ornato, J B Shipley, E M Racht, C M Slovis, K D Wrenn, P E Pepe, S L Almeida, V F Ginger, and T V Fotre.
• Medical College of Virginia, Virginia Commonwealth University, Richmond.
• Ann Emerg Med. 1992 May 1;21(5):518-23.

Study ObjectivesTo evaluate continuous, semiquantitative end-tidal carbon dioxide (ETCO2) monitoring in the prehospital and emergency department setting for confirming proper endotracheal tube placement and assessing prognosis and blood flow during CPR.Type Of ParticipantsAdult patients were included if an endotracheal tube was inserted by prehospital care providers or emergency physicians for cardiac arrest, respiratory arrest, respiratory insufficiency, or airway protection.Design And InterventionsA small, portable, colorimetric ETCO2 detector was attached to the endotracheal tube immediately after each attempted endotracheal tube insertion. The color of the detector membrane was noted at the seventh breath following intubation. The color also was noted and recorded if there was return of spontaneous circulation (defined as a palpable pulse) immediately prior to and following conversion from manual to mechanical CPR. Survival to hospital admission was used as an end point to assess the prognostic value of the initial ETCO2 reading.Main ResultsA total of 227 patients (144 with cardiopulmonary arrest) were studied. In the 83 patients intubated but not in cardiopulmonary arrest, a reading on the ETCO2 detector signifying more than 0.5% ETCO2 was 100% sensitive and 93% specific in detecting proper endotracheal tube placement (100% specific with the endotracheal tube cuff inflated). In cardiac arrest patients, a longer period of estimated arrest appeared to be associated with a lower ETCO2 detector reading. A reading signifying more than 0.5% ETCO2 was 69% sensitive and 100% specific in detecting proper endotracheal tube placement. After proper endotracheal tube placement, all cardiac arrest patients who survived to hospital admission had an initial ETCO2 measurement signifying more than 0.5% ETCO2. Return of spontaneous circulation was usually accompanied by an improved ETCO2 value. Mechanical CPR always produced an ETCO2 value that was as high or higher than that produced by manual CPR.ConclusionThe colorimetric ETCO2 device is highly accurate for confirming endotracheal tube position in nonarrest patients.ConclusionThe colorimetric ETCO2 device is highly accurate for confirming endotracheal tube position in nonarrest patients. In cardiac arrest patients, a reading signifying more than 0.5% ETCO2 confirms correct endotracheal tube placement, while a value signifying less than 0.5% ETCO2 during resuscitation suggests that something is wrong (eg. esophageal intubation, inadequate circulatory flow, prolonged down-time interval, hypothermia, or significant ventilation/perfusion mismatch).

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