Biomaterial Database

Assessment of rebreathing O2 consumption in humans with normal and diseased lungs. 1990

M C Kallay, and R W Hyde, and R J Smith

Department of Medicine and Toxicology, School of Medicine and Dentistry, University of Rochester, New York 14642.

We investigated sources of error in estimating steady-state O2 consumption (VO2ss) by calculating O2 uptake from an anesthesia bag containing O2, He, and N2 during 10-20 s of rebreathing (VO2rb). In 11 normal resting subjects, VO2rb calculated with end-tidal sampling overestimated VO2ss by 16 +/- 15% (SD) (P less than 0.003). This error was proportional to the increase in pulse rate during rebreathing, so that pulse-corrected VO2rb slightly underestimated VO2ss by 2.1 +/- 12.2% (P = 0.66) in the six subjects who rebreathed 28% O2 in the rebreathing bag but significantly underestimated VO2ss by 7.5 +/- 6.7% (P less than 0.04) in the six subjects who rebreathed 21% O2 in the rebreathing bag. During exercise, VO2rb underestimated VO2ss by 4 +/- 12% (P less than 0.001) and by 7 +/- 6% at O2 consumptions greater than 2,000 ml/min if O2 in the rebreathing bag was kept above 20% throughout rebreathing. We found that VO2rb calculated with end-tidal gas concentrations underestimated VO2ss by 1-43% in patients with moderate-to-severe obstructive lung disease, with even greater errors when mixed expired samples were used. The magnitude of the discrepancy correlated poorly with abnormalities in standard pulmonary function tests. Based on these data, VO2rb closely approximates VO2ss in normal subjects, provided hypoxia during rebreathing is avoided and cardiac acceleration from rebreathing is taken into account during resting measurement.

UI	MeSH Term	Description	Entries
D008173	Lung Diseases, Obstructive	Any disorder marked by obstruction of conducting airways of the lung. AIRWAY OBSTRUCTION may be acute, chronic, intermittent, or persistent.	Obstructive Lung Diseases,Obstructive Pulmonary Diseases,Lung Disease, Obstructive,Obstructive Lung Disease,Obstructive Pulmonary Disease,Pulmonary Disease, Obstructive,Pulmonary Diseases, Obstructive
D010100	Oxygen	An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.	Dioxygen,Oxygen-16,Oxygen 16
D010101	Oxygen Consumption	The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)	Consumption, Oxygen,Consumptions, Oxygen,Oxygen Consumptions
D011650	Pulmonary Alveoli	Small polyhedral outpouchings along the walls of the alveolar sacs, alveolar ducts and terminal bronchioles through the walls of which gas exchange between alveolar air and pulmonary capillary blood takes place.	Alveoli, Pulmonary,Alveolus, Pulmonary,Pulmonary Alveolus
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
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
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
D002302	Cardiac Output	The volume of BLOOD passing through the HEART per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with STROKE VOLUME (volume per beat).	Cardiac Outputs,Output, Cardiac,Outputs, Cardiac
D004058	Diffusion	The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.	Diffusions
D005188	False Negative Reactions	Negative test results in subjects who possess the attribute for which the test is conducted. The labeling of diseased persons as healthy when screening in the detection of disease. (Last, A Dictionary of Epidemiology, 2d ed)	False Negative Reaction,Reaction, False Negative,Reactions, False Negative