Alveolar carbon dioxide equilibria in breath-holding experiments

1964 ◽  
Vol 19 (4) ◽  
pp. 755-759
Author(s):  
Delbert S. Barth ◽  
Ralph W. Stacy
Keyword(s):  
Human Subjects ◽  
Venous Blood ◽  
Passive Transfer ◽  
Breath Holding ◽  
Major Objective ◽  
Blood Flows ◽  
Pulmonary Capillary ◽  
Before And After ◽  
Normal Human

An investigation was made of the equilibria approached by alveolar CO2 tension in normal human subjects during breath holding. A major objective of this work was to test the hypothesis that the approached equilibrium was with deoxygenated venous rather than with oxygenated venous blood. The study included determination of CO2 tension of expired air by continuous recording before and after breath holding for various time periods, with simultaneous airflow recordings. Pulmonary blood flows were calculated from these data, and were compared with those obtained by an independent rebreathing technique. The findings indicate that the equilibrium approached in the alveolar spaces during breath holding is between the alveolar air and the blood as it enters the pulmonary capillary. This would indicate that CO2 dumping by passive transfer must precede the uptake of oxygen. Effective pulmonary flows calculated from these data were reproducible and in agreement with those obtained by the rebreathing technique. human pulmonary blood flows; alveolar CO2 transport properties; CO2 rebreathing in humans Submitted on July 22, 1963

Respiratory measurements of cardiac output: from elegant idea to useful test

2004 ◽  
Vol 96 (2) ◽  
pp. 428-437 ◽  
Author(s):  
Gabriel Laszlo
Keyword(s):  
Cardiac Output ◽  
Human Subjects ◽  
Venous Blood ◽  
The Body ◽  
Mixed Venous Blood ◽  
Indirect Determination ◽  
Arterial Blood ◽  
Pulmonary Capillary ◽  
Pulmonary Arterial ◽  
Mixed Venous

The measurement of cardiac output was first proposed by Fick, who published his equation in 1870. Fick's calculation called for the measurement of the contents of oxygen or CO2 in pulmonary arterial and systemic arterial blood. These values could not be determined directly in human subjects until the acceptance of cardiac catheterization as a clinical procedure in 1940. In the meanwhile, several attempts were made to perfect respiratory methods for the indirect determination of blood-gas contents by respiratory techniques that yielded estimates of the mixed venous and pulmonary capillary gas pressures. The immediate uptake of nonresident gases can be used in a similar way to calculate cardiac output, with the added advantage that they are absent from the mixed venous blood. The fact that these procedures are safe and relatively nonintrusive makes them attractive to physiologists, pharmacologists, and sports scientists as well as to clinicians concerned with the physiopathology of the heart and lung. This paper outlines the development of these techniques, with a discussion of some of the ways in which they stimulated research into the transport of gases in the body through the alveolar membrane.

scholarly journals Determination of plasma glucose enrichment in human subjects after primed, constant infusions of 13C‐glycine before and after dietary vitamin B‐6 restriction

2009 ◽  
Vol 23 (S1) ◽  
Author(s):  
Vanessa Rodrigues Silva ◽  
Yvonne Lamers ◽  
Maria Ralat ◽  
Lesa Gilbert ◽  
Christine Keeling ◽  
...  
Keyword(s):  
Plasma Glucose ◽  
Human Subjects ◽  
Dietary Vitamin ◽  
Vitamin B ◽  
Before And After

Determination of oxygenated, mixed venous blood CO2 tension by a breath-holding method

1960 ◽  
Vol 15 (2) ◽  
pp. 225-228 ◽  
Author(s):  
John H. Knowles ◽  
William Newman ◽  
Wallace O. Fenn
Keyword(s):  
Venous Blood ◽  
Mean Value ◽  
Rate Of Change ◽  
Breath Holding ◽  
Mixed Venous Blood ◽  
Clinical Method ◽  
Straight Line ◽  
Zero Rate ◽  
The Mean

At the end of a normal expiration the subject inhaled a given volume of gas mixtures containing different concentrations of CO2 in O2 from 5 to 17%. These were held in the lung for 3 and then again for 12 seconds and were then expired and analyzed. Analyses were made with an infrared analyzer and times were obtained from the graphical record. If the rate of change of CO2 tension is plotted against the mean CO2 tension a straight line results which passes through zero rate at the tension which equals the tension of CO2 in the mixed oxygenated venous blood. From the slope of this straight line it is possible to calculate the cardiac output if the lung volume and slope of the CO2 dissociation curve of the blood are known. Data are presented from 37 experiments on 10 subjects. The method is believed to be theoretically sound but has not been validated as a practical clinical method. Occasional erratic points were obtained, especially in untrained subjects. The standard error of the mean value for venous CO2 tension was 1.9 mm Hg. Submitted on July 13, 1959

The Determination of Triglycerides in Plasma and Tissues

1968 ◽  
Vol 14 (2) ◽  
pp. 156-161 ◽  
Author(s):  
Vishwanath M Sardesai ◽  
Joan A Manning
Keyword(s):  
Human Subjects ◽  
Plasma Samples ◽  
Simple Method ◽  
Glycerol Moiety ◽  
Normal Human ◽  
Time Required ◽  
Colored Compound

Abstract A simple method for the determination of plasma and tissue triglycerides is described. This procedure involves the extraction and saponification of triglycerides, the oxidation of the glycerol moiety to formaldehyde, and the conversion of formaldehyde to a yellow-colored compound, 3,5 diacetyl-1-4 dihydrolulidine, the intensity of which is determined spectrophotometrically. The recoveries of triglycerides added to plasma and tissues have been satisfactory. Plasma samples obtained from normal human subjects are found to have triglycerides in the range 83-200 mg./100 ml. From the standpoint of sensitivity, simplicity, and time required, this technic is believed to be an improvement over previously described procedures for triglyceride determination.

Bronchodilatation, lung recoil, and density dependence of maximal expiratory flow

1982 ◽  
Vol 52 (4) ◽  
pp. 874-878 ◽  
Author(s):  
J. W. Weiss ◽  
E. R. McFadden ◽  
R. H. Ingram
Keyword(s):  
Density Dependence ◽  
Vital Capacity ◽  
Human Subjects ◽  
Beta Agonist ◽  
Elastic Recoil ◽  
Maximal Expiratory Flow ◽  
Before And After ◽  
Normal Human ◽  
Expiratory Flow ◽  
Expiratory Flow Rates

Using normal human subjects we have measured maximal expiratory flow rates with air (Vmaxair) and after a washin of 80% He-20% O2 (VmaxHeO2) and static elastic recoil pressures of the lung [Pst(L)] both before and after administration of a beta-agonist, terbutaline. The effects of inhaled drug were compared with those of the subcutaneously administered agent, each given in doses to produce maximal bronchodilatation as assessed by increases in Vmaxair in the mid-vital capacity. Although there was a significant yet modest decrease in Pst(L) only after injection of the agent, density dependence (DD), assessed as the ratio of VmaxHeO2 to Vmaxair, increased significantly and comparably after either route of administration. A modest decrease in Pst(L), therefore, did not affect the changes in DD.

A model for determining alveolar and small airway dimensions from aerosol recovery data

1985 ◽  
Vol 58 (2) ◽  
pp. 582-591 ◽  
Author(s):  
F. S. Rosenthal
Keyword(s):  
Close Agreement ◽  
Human Subjects ◽  
Small Airway ◽  
Breath Holding ◽  
Morphometric Measurements ◽  
Model Predictions ◽  
Two Parameters ◽  
Best Fit ◽  
Airway Dimensions

A mathematical model is presented that allows the determination of alveolar and small airway dimensions from a series of aerosol recovery measurements performed at different inspiration volumes. The model assumes 1) a symmetric dichotomous lung, 2) representation of airway and alveoli as ensembles of straight tubes, and 3) Gaussian dispersion of the aerosol bolus. Calculations with this model using dimensions given by Weibel show general agreement with experimental data on six human subjects obtained by Palmes et al. (J. Appl. Physiol. 34: 356–360, 1973). Close agreement is found by varying two parameters describing alveolar size and airway size to obtain the best fit. The resulting estimates of size are almost independent of the choice of the dispersion coefficient; however, the estimate of alveolar size is quite dependent on the form of settling assumed during breath holding. The values of alveolar diameter in the six subjects, determined under the assumption of stirred settling, ranged from 0.13 to 0.33 mm, whereas under the assumption of still settling the range was 0.24–0.65 mm. Small airway (generations 18–24) dimensions ranged from 0.41 to 0.66 mm under the still-settling assumption and 0.39 to 0.63 mm under the stirred-settling assumption. With the assumption of an intermediate (partially stirred) form of settling, the alveolar diameter in the six subjects is 0.28 +/- 0.02 mm, in close agreement with morphometric measurements by other investigators. A partially stirred form of settling is also consistent with model predictions of recovery vs. breath-holding time and with cardiogenic gas mixing in the lung.

Colorimetric Determination of Blood Arginase

1955 ◽  
Vol 1 (2) ◽  
pp. 110-116 ◽  
Author(s):  
Max M Friedman ◽  
Edythe Becker
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Human Subjects ◽  
Colorimetric Determination ◽  
Normal Human ◽  
Colorimetric Procedure

Abstract A colorimetric procedure for blood arginase has been described, based on hemolyzing the red blood cells with saponin and determining the urea formed by action of the enzyme on an arginine substrate. The range of blood arginase in a series of normal human subjects has been presented.

scholarly journals Cerebral Blood Flow with the Continuous Infusion of Oxygen-15-Labeled Water

1985 ◽  
Vol 5 (4) ◽  
pp. 566-575 ◽  
Author(s):  
S. C. Jones ◽  
J. H. Greenberg ◽  
R. Dann ◽  
G. D. Robinson ◽  
M. Kushner ◽  
...  
Keyword(s):  
White Matter ◽  
Continuous Infusion ◽  
Human Subjects ◽  
Recovery Coefficient ◽  
Whole Brain ◽  
Positron Emission ◽  
Arterial Concentration ◽  
Normal Human

This work describes the determination of CBF in eight normal human subjects with positron emission tomographic (PET) imaging using the continuous intravenous infusion of H215O. A whole-brain CBF model is described that permits the comparison of the CBF values determined using PET with those obtained using other methods. This model includes a correction for whole-brain recovery coefficient, a correction for the underestimation of flow due to the nonlinearity of the CBF model when considering tissue that includes both gray and white matter, the use of in vitro-determined brain–blood partition coefficients for gray and white matter, and a variation of the equilibrium model that permits the arterial concentration to vary. CBF values using this method compare well with values determined previously. Regional determinations using a brain overlay atlas are presented. Radiation dosimetry for the continuous infusion of H215O is also included.

Sign in / Sign up

Export Citation Format

Share Document