title: Anesthesia machine malfunction simulating spontaneous respiratory effort.
abstract: We present a case in which a dip in the capnogram of an anesthetized patient, which may indicate clinical complications such as spontaneous respiratory effort, was caused by a malfunction of the anesthesia delivery system. The rubber diaphragm of the ventilator relief valve was found to be coated with a sticky substance which may have caused adhesion at the valve seat. This adhesion blocked the flow of excess gas to the scavenging system during exhalation. It was demonstrated that a pressure of 5 cm H2O was needed to overcome this adhesion.
authors.affiliation: Medical College of Wisconsin, Milwaukee 53226.
authors.forename: T
authors.initials: T
authors.lastname: Hensler
authors.forename: M S
authors.initials: MS
authors.lastname: Dhamee
mesh_terms: D000776:Anesthesiology / Q000295:instrumentation*; D002245:Carbon Dioxide / Q000032:analysis*; D004868:Equipment Failure; D006801:Humans; D013058:Mass Spectrometry; D008991:Monitoring, Physiologic; D012119:Respiration
chemical_list: D002245:Carbon Dioxide