Objective: To evaluate the ability of a disposable, colorimetric end–tidal CO2 detector to verify proper endotracheal (ET) tube placement in out–of–hospital cardiac arrest, and to correlate semiquantitative CO2 measurements with the rate of return of spontaneous circulation (ROSC).
Methods: Prospective, observational study using a convenience sample of intubated out–of–hospital cardiac arrest patients. A disposable, colorimetric end–tidal CO2 detector was attached to the ET tube after intubation. In the absence of a colorimetric change, the paramedics reassessed the tube placement and could reintubate the patient. Tube placement was verified at the hospital. Paramedics were instructed to contact the base station and report the colorimetric change upon hospital arrival. ROSC was defined as restoration of a self–sustaining pulse until hospital arrival.
Results: Between December 1990 and May 1993, ET tubes were placed in 566 victims of out–of–hospital cardiac arrest. 541 of the 566 intubations (95.6%) were associated with a color change. In one case with a color change and out–of–hospital clinical evidence of proper tube placement, the tube was determined to be in the esophagus at the hospital. Correct placement of the remaining 565 of 566 (99.8%) tubes was verified. Of the 566 patients who had a colorimetric change, 91 (16%) had ROSC vs one of 25 (4%) patients who did not have a color change. In one subgroup (n = 179), the degree of color change was highly associated with ROSC (p = 0.004).
Conclusions: A disposable, colorimetric end–tidal CO2 detector appears reliable in verifying proper ET tube placement in victims of out–of–hospital cardiac arrest. The degree of color change correlates with the probability of ROSC.