Original contribution| Volume 20, ISSUE 3, P223-229, April 2001

Capnography alone is imperfect for endotracheal tube placement confirmation during emergency intubation1

  • James Li
    Reprint Address: James Li, MD, Mount Auburn Hospital, Division of Emergency Medicine, Harvard Medical School, Cambridge, MA 02238
    Mount Auburn Hospital, Division of Emergency Medicine, Harvard Medical School, Cambridge, Massachusetts, USA
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      This analysis primarily sought to determine the effectiveness of end-tidal capnography for tube placement confirmation during emergency airway management. Secondary objectives were validation of the rate of unanticipated esophageal placement during emergency intubation and quantification of the portion of intubations performed in patients with cardiac arrest where capnography is not recommended. The study was performed in two phases. For the primary objective, a meta-analysis was performed on all experimental capnography trials enrolling emergency populations. For the secondary objectives, inadvertent esophageal intubation and cardiac arrest rates were calculated from a large prospective multicenter observational study of emergency intubation cases. Data analysis included calculation of descriptive statistics, sensitivity, specificity, and confidence intervals (CI). Based on 2,192 intubations, a meta-analysis of previous capnography trials resulted in an aggregate sensitivity of 93% (95% CI 92–94%) and an aggregate specificity of 97% (CI 93–99%) for emergency tube placement confirmation. Thus, for emergency capnography use, the false-negative failure rate (tube in trachea but capnography reports esophagus) was 7% and the false-positive rate (tube in esophagus but capnography reports trachea) was 3%. This translates to potential harm for one patient in every 10 treated with capnographic confirmation alone (number needed to harm: 14 for false-negative, 33 for false-positive, and 10 for both). A further literature review demonstrated no sole method of tube placement confirmation is completely foolproof. Of 4,602 consecutive intubations reported to the National Emergency Airway Registry, 4% of emergency intubation attempts resulted in accidental esophageal intubation, and 10% occurred in nontraumatic cardiac arrest patients. During tracheal intubation of critically ill patients, it is concluded that the rate of accidental esophageal tube placement warrants continued improvement in emergency airway techniques. Misidentification of esophageal placement in the emergency setting may occur with capnography. Multiple methods of tube placement confirmation are superior to any single method because no single method has perfect accuracy.


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