Biomaterial Database

Effect of tidal volume on ventilation maldistribution. 1986

A B Crawford, and M Makowska, and L A Engel

To examine the effect of changing tidal volume (VT) on ventilation distribution, we studied multiple breath nitrogen washouts in 4 normal subjects breathing with a VT of 0.6, 1.0 or 1.5 L. We used a recently developed technique of analysis (Crawford et al., 1985) that distinguishes inhomogeneity of gas concentrations due to the interaction of convection and diffusion in the lung periphery (DCDI) from ventilation maldistribution among larger units determined at more proximal branchpoints (CDI). The results indicate that increases in VT reduce the inhomogeneity due to DCDI but increase that due to CDI. In view of the VT dependence of physiological dead space, derived from arterial PCO2, we speculate that the increase in CDI has a dominant effect on gas exchange.

UI	MeSH Term	Description	Entries
D008176	Lung Volume Measurements	Measurement of the amount of air that the lungs may contain at various points in the respiratory cycle.	Lung Capacities,Lung Volumes,Capacity, Lung,Lung Capacity,Lung Volume,Lung Volume Measurement,Measurement, Lung Volume,Volume, Lung
D009584	Nitrogen	An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.
D011659	Pulmonary Gas Exchange	The exchange of OXYGEN and CARBON DIOXIDE between alveolar air and pulmonary capillary blood that occurs across the BLOOD-AIR BARRIER.	Exchange, Pulmonary Gas,Gas Exchange, Pulmonary
D012044	Regression Analysis	Procedures for finding the mathematical function which best describes the relationship between a dependent variable and one or more independent variables. In linear regression (see LINEAR MODELS) the relationship is constrained to be a straight line and LEAST-SQUARES ANALYSIS is used to determine the best fit. In logistic regression (see LOGISTIC MODELS) the dependent variable is qualitative rather than continuously variable and LIKELIHOOD FUNCTIONS are used to find the best relationship. In multiple regression, the dependent variable is considered to depend on more than a single independent variable.	Regression Diagnostics,Statistical Regression,Analysis, Regression,Analyses, Regression,Diagnostics, Regression,Regression Analyses,Regression, Statistical,Regressions, Statistical,Statistical Regressions
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
D012126	Respiratory Dead Space	That part of the RESPIRATORY TRACT or the air within the respiratory tract that does not exchange OXYGEN and CARBON DIOXIDE with pulmonary capillary blood.	Dead Space, Respiratory,Dead Spaces, Respiratory,Respiratory Dead Spaces,Space, Respiratory Dead,Spaces, Respiratory Dead
D001944	Breath Tests	Any tests done on exhaled air.	Breathalyzer Tests,Breath Test,Breathalyzer Test,Test, Breath,Test, Breathalyzer,Tests, Breath,Tests, Breathalyzer
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D013990	Tidal Volume	The volume of air inspired or expired during each normal, quiet respiratory cycle. Common abbreviations are TV or V with subscript T.	Tidal Volumes,Volume, Tidal,Volumes, Tidal