title: An early example of evidence-based medicine: hypoxemia due to nitrous oxide.
abstract: Diffusion anoxia. By Bernard Raymond Fink. Anesthesiology 1955; 16:511-14. In 1955, Dr. Bernard Raymond Fink published his findings that described the mechanism by which hypoxemia occurred when nitrous oxide-oxygen anesthesia was discontinued and room air breathing commenced. Using an ear oximeter and brachial artery blood gases, he measured oxygen saturation in eight healthy patients who had received 75% nitrous oxide-25% oxygen for gynecologic surgery. He showed that oxygen saturation decreased from 5% to 10% and often reached a value below 90% when the patient began room air breathing after the nitrous oxide-oxygen was discontinued. The effect was seen over a 10-min period. He concluded that "anoxia arises because the outward diffusion of nitrous oxide lowers the alveolar partial pressure of oxygen." This phenomenon can become a causative factor of cardiac arrest in patients with impaired pulmonary or cardiac reserves.
authors.affiliation: Department of Anesthesiology, University of Washington, Seattle 98195, USA. fcheney@u.washington.edu
authors.forename: Frederick W
authors.initials: FW
authors.lastname: Cheney
mesh_terms: D004058:Diffusion; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000209:etiology*; D009609:Nitrous Oxide / Q000009:adverse effects*; D010100:Oxygen / Q000097:blood
chemical_list: D009609:Nitrous Oxide; D010100:Oxygen