Table 10.

Modes of confirmation of tracheal intubation, with test sensitivities, specificities and select causes of false negative and false positive results

Confirmation of tracheal intubation
Method	Published sensitivity range, if available (percentage of tracheal intubations correctly identified by a positive test result)	Published specificity range, if available (percentage of esophageal intubations correctly identified by a negative test result)	Select causes of a false negative result (tube is in trachea, but a negative test result suggests it is in the esophagus)	Select causes of a false positive result (tube is in esophagus or pharynx, but a positive test result suggests it is in the trachea)
Waveform capnography	98–100% (non-arrest)212,217–223 68% (arrest)217	100% (non-arrest)212,217–221 100% (arrest)217	• Equipment malfunction or disconnect • Severe bronchospasm • Kinked or occluded tube • Tracheal obstruction • Tracheal tube cuff not inflated • Obstruction of pulmonary circulation	• Failure to assess for sustained waveforms • Tube lying in pharynx outside larynx (e.g., cuff above the cords) • Recent extensive use of FMV or bi-level positive airway pressure non-invasive ventilation222 • Ingestion of antacid or carbonated beverages
Colorimetric capnometry	97–100% (non- arrest)220,223–225 69–85% (arrest)223,225,226	91–100% (non-arrest)220,223,224 100% (arrest)223,226	As above, plus: • Low cardiac output/severe hypotension • ETCO2 < 2–5% • Neonates and infants227	As above, plus: • Contamination of detector with acidic gastric contents;228 • Recent instillation of medications through the tracheal tube including epinephrine, atropine, surfactant,229 naloxone.
Visualization of tracheal tube between cords	No data	No data	• Adverse patient anatomy precludes a view of any aspect of the larynx during DL or Mac-VL	• “Glottic impersonation”: entrance to hypopharynx is misinterpreted as the larynx during excess lifting pressure on laryngoscope230 • Inadvertent intubation of a tracheoesophageal fisutla231,232
Endoscopic visualization of trachea through tracheal tube	No data	No data	• Visualization obscured by blood, secretions or aspirated gastric contents • Scope fogging	No data
Ultrasound	92–99%233–236	93–100%233–236	• Image misinterpretation by inexperienced clinician	• Image misinterpretation by inexperienced clinician
Auscultation	70–100%217–219,221,237,238	50–95%217–219,221,237,238	• Poor quality stethoscope • Noisy environment • Thick chest & abdominal walls • Severe bronchospasm	• Thin chest/abdominal wall • Transmitted sounds • Expectation bias
Esophageal detector device	83–100%217,239–246	92–100%217,239–246	• Obesity (BMI > 35) • Parturients at induction of general anesthesia • < 10 kg • Bronchospasm; mainstem intubation • Tube occluded by pulmonary edema, mucus plug or blood	• Significant recent FMV or SGA ventilation • Bulb filling with emesis rather than gas.
Tube misting	100%237,247,248	15–71%237,247,248	No data	• The esophagus is also a moist environment.

BMI = body mass index; DL = direct laryngoscopy; ETCO₂ = end-tidal carbon dioxide; FMV = face-mask ventilation; Mac-VL = Macintosh geometry blade video laryngoscopy; SGA = supraglottic airway