Biomaterial Database

Diurnal variation of the diffusing capacity of the lung: is it real? 1987

T M Frey, and R O Crapo, and R L Jensen, and C G Elliott

LDS Hospital, Pulmonary Division, Salt Lake City, UT 84143.

The single-breath diffusing capacity of the lung (DLCO) has been reported to decrease at a rate of 1.2 to 2.2% per hour during usual daytime hours. In an attempt to confirm these findings, we measured DLCO using both single-breath (DLCOs) and rebreathing techniques (DLCOR) in healthy, nonsmoking volunteers over the course of a day and again at different times on different days. Serial testing over a day showed a consistent fall (0.39%/h for DLCOS and 0.56%/h for DLCOR) in DLCO that was explained by increasing carboxyhemoglobin levels (COHb) and decreasing hemoglobin concentrations (Hb). When subjects were tested at different times on different days and compared using a paired t test, there was no change in DLCO over the time of day using either technique. We conclude that there is no diurnal variation in DLCO when adjusted for changes in Hb and COHb. The measurement of COHb levels and Hb concentrations for adjustment of DLCO results is important for correct interpretation of both individual and group studies of DLCO and should be performed whenever possible.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D011653	Pulmonary Diffusing Capacity	The amount of a gas taken up, by the pulmonary capillary blood from the alveolar gas, per minute per unit of average pressure of the gradient of the gas across the BLOOD-AIR BARRIER.	Capacity, Pulmonary Diffusing,Diffusing Capacity, Pulmonary
D012016	Reference Values	The range or frequency distribution of a measurement in a population (of organisms, organs or things) that has not been selected for the presence of disease or abnormality.	Normal Range,Normal Values,Reference Ranges,Normal Ranges,Normal Value,Range, Normal,Range, Reference,Ranges, Normal,Ranges, Reference,Reference Range,Reference Value,Value, Normal,Value, Reference,Values, Normal,Values, Reference
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
D012129	Respiratory Function Tests	Measurement of the various processes involved in the act of respiration: inspiration, expiration, oxygen and carbon dioxide exchange, lung volume and compliance, etc.	Lung Function Tests,Pulmonary Function Tests,Function Test, Pulmonary,Function Tests, Pulmonary,Pulmonary Function Test,Test, Pulmonary Function,Tests, Pulmonary Function,Function Test, Lung,Function Test, Respiratory,Function Tests, Lung,Function Tests, Respiratory,Lung Function Test,Respiratory Function Test,Test, Lung Function,Test, Respiratory Function,Tests, Lung Function,Tests, Respiratory Function
D002263	Carboxyhemoglobin		Carbomonoxyhemoglobin,Carbonmonoxyhemoglobin,Carbonylhemoglobin,Carboxyhemoglobin A,Carboxyhemoglobin C
D002940	Circadian Rhythm	The regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs or environmental and physiological stimuli.	Diurnal Rhythm,Nyctohemeral Rhythm,Twenty-Four Hour Rhythm,Nycthemeral Rhythm,Circadian Rhythms,Diurnal Rhythms,Nycthemeral Rhythms,Nyctohemeral Rhythms,Rhythm, Circadian,Rhythm, Diurnal,Rhythm, Nycthemeral,Rhythm, Nyctohemeral,Rhythm, Twenty-Four Hour,Rhythms, Circadian,Rhythms, Diurnal,Rhythms, Nycthemeral,Rhythms, Nyctohemeral,Rhythms, Twenty-Four Hour,Twenty Four Hour Rhythm,Twenty-Four Hour Rhythms
D005260	Female		Females
D006454	Hemoglobins	The oxygen-carrying proteins of ERYTHROCYTES. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements.	Eryhem,Ferrous Hemoglobin,Hemoglobin,Hemoglobin, Ferrous
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man