title: Breathing system filters used with Entonox.
authors.forename: A R
authors.initials: AR
authors.lastname: Wilkes
authors.forename: A J
authors.initials: AJ
authors.lastname: Stevens
mesh_terms: D016362:Analgesia, Obstetrical / Q000379:methods; D003428:Cross Infection / Q000517:prevention & control*; D004203:Disinfection / Q000592:standards*; D006801:Humans; D012121:Respiration, Artificial / Q000295:instrumentation*