Biomaterial Database

Rebreathing characteristics of the Bain circuit. An experimental and theoretical study. 1984

O Stenqvist, and H Sonander

The Bain circuit was studied in a model lung on the assumption that, in addition to the ratio of fresh gas flow to total ventilation (VFG/VE), different time fractions of the respiratory cycle might influence rebreathing. We found that the time fraction for active expiration (FEt) governed rebreathing for each VFG/VE value. With FEt as an independent variable, a theoretical formula was derived for rebreathing. Rearranging this formula made it possible to calculate the necessary increase in ventilation to keep end-tidal carbon dioxide constant for each VFG/VE. Thus, at a fresh gas flow of 70 ml kg-1 min-1, VI has to be increased 2.6 times. For spontaneously breathing patients inhalation anaesthetics that do not depress carbon dioxide sensitivity seem to be better suited to use in the Bain circuit. The FECO2 can then be kept constant through increased ventilation in spite of the concomitant increase in rebreathing.

UI	MeSH Term	Description	Entries
D008954	Models, Biological	Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.	Biological Model,Biological Models,Model, Biological,Models, Biologic,Biologic Model,Biologic Models,Model, Biologic
D012119	Respiration	The act of breathing with the LUNGS, consisting of INHALATION, or the taking into the lungs of the ambient air, and of EXHALATION, or the expelling of the modified air which contains more CARBON DIOXIDE than the air taken in (Blakiston's Gould Medical Dictionary, 4th ed.). This does not include tissue respiration (	Breathing
D002245	Carbon Dioxide	A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.	Carbonic Anhydride,Anhydride, Carbonic,Dioxide, Carbon
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000769	Anesthesia, Inhalation	Anesthesia caused by the breathing of anesthetic gases or vapors or by insufflating anesthetic gases or vapors into the respiratory tract.	Insufflation Anesthesia,Anesthesia, Insufflation,Inhalation Anesthesia
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor