Diagnostic accuracy of end-tidal carbon dioxide detection in determining correct placement of nasogastric tube: An updated systematic review with meta-analysis

Janita Pak Chun Chau, Xu Liu*, Kai Chow Choi, Suzanne Hoi Shan Lo, Simon Kwun Yu Lam, Kam Ming Chan, Jie Zhao, David R. Thompson

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Misplacement of the nasogastric tube in the respiratory tract could cause serious complications and even death. Thus, nasogastric tube verification is necessary for optimal patient safety and comfort. Although end-tidal carbon dioxide detection is considered an effective approach to determine nasogastric tube location, there is a paucity of up-to-date evidence.

To review the diagnostic accuracy of end-tidal carbon dioxide detection in determining inadvertent airway intubation and verifying correct placement of nasogastric tubes.

A systematic review and meta-analysis.

We searched clinical trials that evaluated the diagnostic accuracy of colorimetric capnometry or capnography in detecting nasogastric tubes located in the airway and differentiating between inadvertent airway intubation and correct nasogastric tube placement in any adult care setting. Four English language databases - Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and CINAHL - and four Chinese language databases - China Biomedical Literature Database, WanFang Data, China National Knowledge Infrastructure, and Airiti Library - were searched from July 2009 to March 2021. Clinical trial registration databases and reference lists of included studies and relevant reviews were also searched. Two reviewers extracted the data of all included studies using a data extraction form. Two reviewers assessed the methodological quality independently with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. We conducted meta-analysis using the hierarchical bivariate model and estimated the pool sensitivity and specificity of capnography and colorimetric capnometry. Forest plots were generated to display the results. Heterogeneity was investigated by meta-regression. The certainty of evidence was evaluated with the Grading of Recommendations Assessment, Development and Evaluations framework.

Of 1,155 records identified, seven new studies were added to this update and a total of 16 studies were analysed in the systematic review. The total absolute number of true positive, false negative, true negative, and false positive observations were 142, 6, 1,500, and 65 respectively. Low to very low certainty of evidence indicated that the use of colorimetric capnometry or capnography is potentially an effective method in differentiating between respiratory and nasogastric tube placement for critically ill adult patients. Pooled results (13 studies, 1,541 intubations) for sensitivity and specificity were 0.96 (95% confidence interval [0.88, 0.99]) and 0.99 (95% confidence interval [0.96, 1.00]), respectively.

Colorimetric capnometry and capnography may have the potential to be of high sensitivity and specificity for the detection of inadvertent airway nasogastric tube placements in critically ill adults. More evidence is required to generalise the updated findings to different types of patients and settings.
Original languageEnglish
Article number104071
Number of pages14
JournalInternational Journal of Nursing Studies
Early online date24 Aug 2021
Publication statusPublished - 10 Sept 2021


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