False-positive colorimetric capnometry after ingestion of carbonated beverages.
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.
Keller
William Ryan
WR
Department of Pediatrics, University of Oklahoma School of Medicine, Oklahoma City, OK, USA.
Biehler
Jefrey
J
Linares
Marc Yves-Rene
MY
Garcia-Pena
Barbara M
BM
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