title: False-positive colorimetric capnometry after ingestion of carbonated beverages.
abstract: OBJECTIVE
  To investigate the potential for false-positive colorimetric capnometric readings during esophageal intubation after ingestion of carbonated beverages.
  
  
  METHODS
  The study was conducted in the human patient simulation laboratory of a tertiary care pediatric hospital. The sole outcome measurement was the capnometric indicator membrane color after expiration for 10 breaths. Readings were recorded for scenarios simulating 8 different models.
  
  
  RESULTS
  For all carbonated beverage trials with a cuffed endotracheal tube (ETT) and those with 2 and 6 oz of beverage in the gastric sac with an uncuffed ETT, a false-positive result was observed on the capnometer's indicator for breaths 1 through 10. The sensitivity of the capnometer for the detection of CO2 after full exhalation of breath 6 for these trials was 100%. For trials containing 12 oz in the gastric sac and an uncuffed ETT, yellow was observed on the capnometer indicator for breaths 1 through 3, tan for breaths 4 through 6, and purple for breath 7. The sensitivity of the capnometer for the detection of adequate CO2 after full exhalation of breath 6 for these trials was 0%. The overall sensitivity of the capnometer for the carbonated beverage models with a cuffed ETT was 100%, whereas the combined sensitivity for the trials with an uncuffed ETT was 67%.
  
  
  CONCLUSIONS
  Under proper circumstances, a significant potential exists for false-positive colorimetric capnometric results in the presence of even small amounts of carbonated beverages.
authors.affiliation: Department of Pediatrics, University of Oklahoma School of Medicine, Oklahoma City, OK, USA.
authors.forename: William Ryan
authors.initials: WR
authors.lastname: Keller
authors.forename: Jefrey
authors.initials: J
authors.lastname: Biehler
authors.forename: Marc Yves-Rene
authors.initials: MY
authors.lastname: Linares
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Garcia-Pena
mesh_terms: D019296:Capnography / Q000379:methods*; D002253:Carbonated Beverages; D002648:Child; D003124:Colorimetry; D005189:False Positive Reactions; D006801:Humans; D007442:Intubation, Intratracheal; D016544:Patient Simulation; D012680:Sensitivity and Specificity