Clinical tests for confirming tracheal intubation or excluding oesophageal intubation: a diagnostic test accuracy systematic review and meta-analysis

Unrecognised oesophageal intubation causes preventable serious harm to patients undergoing tracheal intubation. When capnography is unavailable or doubted, clinicians still use clinical findings to confirm tracheal intubation, or exclude oesophageal intubation, and false reassurance from clinical examination is a recurring theme in fatal cases of unrecognised oesophageal intubation. We conducted a systematic review and meta-analysis of the diagnostic accuracy of five clinical examination tests and the oesophageal detector device when used to confirm tracheal intubation. We searched four databases for studies reporting index clinical tests against a reference standard, from inception to 28 February 2023. We included 49 studies involving 10,654 participants. Methodological quality was overall moderate to high. We looked at misting (three studies, 115 participants); lung auscultation (three studies, 217 participants); combined lung and epigastric auscultation (four studies, 506 participants); the oesophageal detector device (25 studies, 3024 participants); 'hang-up' (two non-human studies); and chest rise (one non-human study). The reference standards used were capnography (22 studies); direct vision (10 studies); and bronchoscopy (three studies). When used to confirm tracheal intubation, misting has a false positive rate (95%CI) of 0.69 (0.43-0.87); lung auscultation 0.14 (0.08-0.23); five-point auscultation 0.18 (0.08-0.36); and the oesophageal detector device 0.05 (0.02-0.09). Tests to exclude events that invariably lead to severe damage or death must have a negligible false positive rate. Misting or auscultation have too high a false positive rate to reliably exclude oesophageal intubation and there is insufficient evidence to support the use of 'hang-up' or chest rise. The oesophageal detector device may be considered where other more reliable means are not available, though waveform capnography remains the reference standard for confirmation of tracheal intubation.

Automated summary

Unrecognized esophageal intubation can cause preventable harm to patients. This study aimed to evaluate the diagnostic accuracy of various clinical examination tests and the esophageal detector device in confirming tracheal intubation. The results showed that misting and auscultation have a high false positive rate and are not reliable for excluding esophageal intubation. The esophageal detector device may be considered as an alternative when other methods are not available, but waveform capnography remains the gold standard.