The effect of vinegar on colorimetric end-tidal carbon dioxide determination after esophageal intubation.

This study examines the effect of vinegar placement in the stomach on colorimetric end-tidal carbon dioxide (ETCO(2)) determinations after esophageal intubation. Using a blinded, prospective, before and after post-mortem swine model, colorimetric ETCO(2) was determined after aspiration of the stomach contents and after placement of aliquots of saline and vinegar. Data were compiled from 12 swine within 120 min post-mortem. In 12 of 12 trials, the ETCO(2) detector turned yellow, indicating "positive" determination of CO(2), but did not return to "purple" with multiple insufflations with 100% O(2). We conclude that esophageal intubation with a small amount of vinegar in the stomach can cause an irreversible color change of the detector to yellow. Color change indicating the presence of carbon dioxide without subsequent color change back to purple with insufflation with 100% oxygen should arouse suspicion of improper placement of the endotracheal tube.