title: Endotracheal tube placement confirmation: 100% sensitivity and specificity with sustained four-phase capnographic waveforms in a cadaveric experimental model.
abstract: Waveform capnography is considered the gold standard for verification of proper endotracheal tube placement, but current guidelines caution that it is unreliable in low-perfusion states such as cardiac arrest. Recent case reports found that long-deceased cadavers can produce capnographic waveforms. The purpose of this study was to determine the predictive value of waveform capnography for endotracheal tube placement verification and detection of misplacement using a cadaveric experimental model.
  
  
  
  We conducted a controlled experiment with two intubated cadavers. Tubes were placed within the trachea, esophagus, and hypopharynx utilizing video laryngoscopy. We recorded observations of capnographic waveforms and quantitative end-tidal carbon dioxide (ETCO2) values during tracheal versus extratracheal (i.e., esophageal and hypopharyngeal) ventilations.
  
  
  
  106 and 89 tracheal ventilations delivered to cadavers one and two, respectively (n=195) all produced characteristic alveolar waveforms (positive) with ETCO2values ranging 2-113mmHg. 42 esophageal ventilations (36 to cadaver one and 6 to cadaver two), and 6 hypopharyngeal ventilations (4 to cadaver one and 2 to cadaver two) all resulted in non-alveolar waveforms (negative) with ETCO2values of 0mmHg. Esophageal and hypopharyngeal measurements were categorized as extratracheal (n=48). A binary classification test showed no false negatives or false positives, indicating 100% sensitivity (NPV 1.0, 95%CI 0.98-1.00) and 100% specificity (PPV 1.0, 95%CI 0.93-1.00).
  
  
  
  Though current guidelines question the reliability of waveform capnography for verifying endotracheal tube location during low-perfusion states such as cardiac arrest, our findings suggest that it is highly sensitive and specific.
authors.affiliation: Department of Emergency Medicine, Orlando Regional Medical Center, 86 West Underwood Street, Suite 200, Orlando, FL 32806, United States.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Silvestri
authors.affiliation: Department of Emergency Medicine, Orlando Regional Medical Center, 86 West Underwood Street, Suite 200, Orlando, FL 32806, United States.
authors.forename: Jay G
authors.initials: JG
authors.lastname: Ladde
authors.affiliation: Department of Emergency Medicine, Orlando Regional Medical Center, 86 West Underwood Street, Suite 200, Orlando, FL 32806, United States. Electronic address: jamfort@gmail.com.
authors.forename: James F
authors.initials: JF
authors.lastname: Brown
authors.affiliation: Department of Emergency Medicine, Orlando Regional Medical Center, 86 West Underwood Street, Suite 200, Orlando, FL 32806, United States.
authors.forename: Jesus V
authors.initials: JV
authors.lastname: Roa
authors.affiliation: Department of Emergency Medicine, Orlando Regional Medical Center, 86 West Underwood Street, Suite 200, Orlando, FL 32806, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Hunter
authors.affiliation: Department of Emergency Medicine, Orlando Regional Medical Center, 86 West Underwood Street, Suite 200, Orlando, FL 32806, United States.
authors.forename: George A
authors.initials: GA
authors.lastname: Ralls
authors.affiliation: Department of Emergency Medicine, Orlando Regional Medical Center, 86 West Underwood Street, Suite 200, Orlando, FL 32806, United States.
authors.forename: Linda
authors.initials: L
authors.lastname: Papa
mesh_terms: D002102:Cadaver; D019296:Capnography / Q000379:methods / Q000592:standards*; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D008962:Models, Theoretical; D012680:Sensitivity and Specificity
keywords: Airway management; Capnography; Critical care; End-tidal carbon dioxide; Intubation; Resuscitation