Checking of gas sampling tube by direct measurement of exhaled breath.

EDITOR: We read with interest the article published by Gauthama and Morris [1] in which the authors reported the findings of a survey of UK anaesthetists for checking the capnograph before anaesthesia. The authors reported that majority of UK anaesthetists use exhaled breath to check the capnograph but the practice is not universal due to concerns of sterility. We wish to report a critical incident related to a gas sampling tube that supports the use of exhaled breath during checking of an anaesthetic machine and a breathing circuit. A partial break in the gas sampling tube was not detected on visual inspection and machine check was performed following published guidelines [2]. We believe, had we performed a direct measurement of exhaled breath, the break in the gas sampling tube would have been detected.