Unidirectional valve malfunction by the breakage or malposition of disc - two cases report -

Korean J Anesthesiol. 2013 Oct;65(4):337-40. doi: 10.4097/kjae.2013.65.4.337. Epub 2013 Oct 24.


Malfunction of the unidirectional valve in a breathing circuit system may cause hypercapnia from the rebreathing of expired gas, ventilation failure, and barotrauma. Capnography is a useful method for monitoring the integrity of the unidirectional valve. We experienced two cases of malfunction of a unidirectional valve which caused leakage and reverse flow, diagnosed early as a change of the capnographic waveform. One case was caused by expiratory unidirectional valve breakage. The other was caused by an incorrectly-assembled inspiratory unidirectional valve.

Keywords: Capnography; Hypercapnia; Unidirectional valve.