title: A simplified concept for controlling oxygen mixtures in the anaesthetic machine--better, cheaper and more user-friendly?
abstract: Modern anaesthetic machines are equipped with several safety components to prevent delivery of hypoxic mixtures. However, such a technical development has increased the complexity of the equipment. We report a reconstructed anaesthetic machine in which a paramagnetic oxygen analyzer has provided the means to simplify the apparatus. The new machine is devoid of several components conventionally included to prevent hypoxic mixtures: oxygen failure protection device, reservoir O2 alarm, N2O/air selector, and proportioning system for oxygen/nitrous oxide delivery. These devices have been replaced by a simple safety system using a paramagnetic oxygen analyzer at the common gas outlet, which in a feed-back system cuts off the supply of nitrous oxide whenever the oxygen concentration falls below 25%. The simplified construction of the anaesthetic machine has important consequences for safety, cost and user-friendliness. Reducing the complexity of the construction also simplifies the pre-use checkout procedure, and an efficient 5-point check list is presented for the new machine.
authors.affiliation: Department of Clinical Engineering, National Hospital, University of Oslo, Norway.
authors.forename: J A
authors.initials: JA
authors.lastname: Berge
authors.forename: L
authors.initials: L
authors.lastname: Gramstad
authors.forename: S
authors.initials: S
authors.lastname: Grimnes
mesh_terms: D000769:Anesthesia, Inhalation / Q000191:economics / Q000295:instrumentation*; D003365:Costs and Cost Analysis; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation; D004582:Electronics, Medical / Q000295:instrumentation; D004867:Equipment Design; D004868:Equipment Failure; D004869:Equipment Safety; D005246:Feedback; D006801:Humans; D000860:Hypoxia / Q000517:prevention & control; D009609:Nitrous Oxide / Q000008:administration & dosage / Q000032:analysis; D010100:Oxygen / Q000008:administration & dosage* / Q000032:analysis
chemical_list: D009609:Nitrous Oxide; D010100:Oxygen