UNIGE document Scientific Article
previous document  unige:56102  next document
add to browser collection
Title

Viscosity and density of common anaesthetic gases: implications for flow measurements

Authors
Asztalos, T
Sly, P D
Published in British Journal of Anaesthesia. 2001, vol. 87, no. 4, p. 602-7
Abstract Although viscosity (mu) is a crucial factor in measurements of flow with a pneumotachograph, and density (rho) also plays a role in the presence of turbulent flow, these material constants are not available for the volatile anaesthetic agents commonly administered in clinical practice. Thus, we determined experimentally mu and rho of pure volatile anaesthetic agents. Input impedance of a rigid-wall polyethylene tube (Zt) was measured when the tube was filled with various mixtures of carrier gases (air, 100% oxygen, 50% oxygen+50% nitrogen) to which different concentrations of volatile anaesthetic inhalation agents (halothane, isoflurane, sevoflurane, and desflurane) had been added. Mu and rho were calculated from real and imaginary portions of Zt, respectively, using the appropriate physical equations. Multiple linear regression was applied to estimate mu and rho of pure volatile agents. Viscosity values of pure volatile agents were markedly lower than those for oxygen or nitrogen. Clinically applied concentrations, however, did not markedly affect the viscosity of the gas mixture (maximum of 3.5% decrease in mu for 2 MAC desflurane). In contrast, all of the volatile agents significantly affected rho even at routinely used concentrations. Our results suggest that the composition of the carrier gas has a greater impact on viscosity than the amount and nature of the volatile anaesthetic agent whereas density is more influenced by volatile agent concentrations. Thus, the need for a correction factor in flow measurements with a pneumotachograph depends far more on the carrier gas than the concentration of volatile agent administered, although the latter may play a role in particular experimental or clinical settings.
Keywords Anesthetics, Inhalation/chemistryHalothane/chemistryHumansIsoflurane/analogs & derivatives/chemistryMethyl Ethers/chemistryRheologyViscosity
Identifiers
PMID: 11878731
Full text
Article (Published version) (113 Kb) - public document Free access
Structures
Research group Enfants et hyperréactivité bronchique (69)
Citation
(ISO format)
HABRE, Walid et al. Viscosity and density of common anaesthetic gases: implications for flow measurements. In: British Journal of Anaesthesia, 2001, vol. 87, n° 4, p. 602-7. https://archive-ouverte.unige.ch/unige:56102

137 hits

34 downloads

Update

Deposited on : 2015-05-11

Export document
Format :
Citation style :