Rate of disappearance of labeled carbon dioxide from the lungs of humans during breath holding: a method for studying the dynamics of pulmonary CO2 exchange

Hyde, Richard W.; Puy, Ricardo J. M.; Raub, William F.; Forster, R. E.

doi:10.1172/jci105846

Cited by 35 publications

(15 citation statements)

References 35 publications

(48 reference statements)

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“…Kim et al [5] suggested that there should only be a 1% difference between lung volumes determined by a CO2 method (ELV) or by an 02 method. Our results corroborate those of Dubois et al The dynamic behavior of CO 2 exchange in pulmonary tissue has been measured [6][7][8][9]. The general conclusion is that CO2 exchanges so rapidly between the capillary bed, pulmonary tissue, and alveolar gas that for transient gas exchange studies this system may be considered as one larger equivalent' lung volume.…”

Section: Introductionsupporting

confidence: 91%

A deep breath method for noninvasive estimation of cardiopulmonary parameters

Mitchell

1988

J Clin Monit Comput

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A specific ventilation pattern incorporating a single deep breath is used to demonstrate the possibility of estimating six cardiopulmonary parameters by measuring respiratory flow and expired oxygen and carbon dioxide concentrations at the mouth. Equations are derived from both alternating and continuous ventilation models of gas exchange which allow the six parameter estimates to be computed. The results indicate that pulmonary capillary blood flow, functional residual capacity, equivalent lung volume, mixed venous PO2 and PCO2, and pulmonary tissue plus capillary blood volume can be estimated in subjects with normal gas exchange. The use of a mechanical ventilator to provide a uniform ventilation pattern before and after the ventilator induced deep breath is the key to the methods simplicity. This allowed parameter estimates to be obtained which could then be analyzed for accuracy and precision. The feasibility of estimating these parameters, demonstrated by the present study, suggests that a recursive least squares estimation procedure could be used to recover the time variation of each parameter during exercise stress testing of subjects with normal or nearly normal gas exchange.

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Section: Introductionsupporting

confidence: 91%

A deep breath method for noninvasive estimation of cardiopulmonary parameters

Mitchell

1988

J Clin Monit Comput

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“…When the following experimental conditions are given: trPv~o2 = 50 Torr, PA~o2 = 40.8 Torr, and the capillary blood volume = 90 ml, the DL(C02) is estimated to be 155 ml • min -1 • Torr-1 for the t~ of 0.7 s. HYDE et al (1968) andPIIPER et al (1980) measured the DL(C02) by using 13C02 in human lungs. The DL(C02) at rest measured by HYDE et al (1968) was higher than 200 ml • min -1 • Torr -1 and that obtained by PIIPER et al (1980) was, on an average, 180 ml • min -1 • Torr-1. According to PIIPER et al (1980), the slope of the CO2 dissociation curve of 13C02 was 1.18 vol% •Torr-1, or ca.…”

Section: Evaluation Of F(ap) and Contact Timementioning

confidence: 99%

“…Thus, it may be safe to say that the alveolar membrane is much more permeable to CO2 than the RBC membrane at least in the normal subject. HYDE et al (1968) andPIIPER et al (1980) reported that the diffusion of CO2 is limited, to some extent, by the alveolar membrane. On the other hand, SCHUSTER (1985) measured the CO2 diffusivity across the alveolar membrane by using 18O labeled carbon dioxide in human subjects.…”

Section: Evaluation Of F(ap) and Contact Timementioning

confidence: 99%

A method for estimating contact time of red blood cells through lung capillary from O2 and CO2 concentrations in rebreathing air in man.

et al. 1987

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The gas exchange ratio (R) obtained from 02 and CO2 concentrations measured in rebreathing air usually shows a linear relation to the Pco2. By referring to this relation and the R which equals the Haldane effect coefficient and zero, the true-and oxygenated-venous Pco2 are obtained in addition to the alveolar Pco2. When these Pco2 are evaluated, the R-P02 line can also be computed theoretically from a numerical solution on the overall 02 and CO2 diffusions in the red blood cell. By comparing both the experimental and theoretical R-P02 lines with each other, we derived a contact time equation. Since the linear approximation of the R-P02 relation gave rise to an error in the contact time (ta), first a factor to correct the linearity of the R-P02 line was derived. Next, using these parameter values, t~ was quantitatively determined from experimental data obtained during rebreathing in 5 normal subjects and it was compared with that estimated from the pulmonary diffusing capacity for CO in the same rebreathing experiment. When the extracellular HCO3 -dehydration rate was taken to be 0.1 s in time constant, the t~, being ca. 0.7 and 0.4 s at rest and during exercise, respectively, showed good agreement with those obtained from the diffusing capacity for CO.

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“…The logarithmic rise in 328 Pereira/Reis/Landriault/Cates/Rigatto Alveolar Gases during Periodic Breathing alveolar PCO2 has been observed in apneas lasting for periods greater than 11 min [6][7][8][15][16][17][18]. The fact that long and short apneas appear to occur randomly along the regression line of PaCK on PACC>2 for individual infants indicates that other factors aside from chemi cal drive are responsible for the length of apnea.…”

Section: Discussionmentioning

confidence: 99%

“…If there is no threshold for indi vidual babies, how much variability does exist in the PaC0 2 at which apnea occurs and what are the corresponding PAC>2 levels? Finally, we wanted to take advantage of the fact that these infants usually have apneas of various lengths, to discover whether the increase in PAC 0 2 during apnea is logarithmic as re ported in adult subjects [4][5][6], Because apneas in these infants are shorter than those in adult subjects, we hypothesized that this rise would be linear.…”

Section: Introductionmentioning

confidence: 99%

Profile of Alveolar Gases during Periodic and Regular Breathing in Preterm Infants

Pereira

Reis²,

Landriault³

et al. 1995

Neonatology

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To determine the changes in alveolar PCO₂ (P_ACO₂) and PO₂ (P_AO₂) during periodic and regular breathing epochs in the same infants, we studied 11 preterm infants during quiet sleep (birth weight 1,630 ± 94 g; gestational age 31 ± 1 weeks; postnatal age 32 ± 3 days). A total of 94 breathing/apneic cycles were analyzed and compared with regular periods. During periodic and regular breathing epochs, there were negative correlations of P_AO₂ on P_ACO₂. Short (5 s) and long ( > 5 s) apneas for individual infants occurred along the regression line for that infant. There was not a single overall critical P_ACO₂ below which apnea occurred, but for individual infants the P_ACO₂ and the P_ACO₂ of the breath preceding apnea varied within a limited range. Apneas occurred in clusters of P_ACO₂ and P_AO₂ along the average regression line of P_AO₂ on P_ACO₂. Analysis of the data showed that apnea occurred at the lowest P_ACO₂ and highest P_AO₂ levels if allowance was made for circulation time. During apnea, ‘the best fit’ for the increase in P_ACO₂ and the decrease in P_AO₂ was linear, rather than logarithmic. The findings suggest the following. (1) There is not a single overall critical level of P_ACO₂ for apnea to occur, but in a given infant this level varies within a limited range. This indicates that these infants are likely breathing near the apnea threshold. (2) Short and long apneas appear to occur randomly along the regression of P_AO₂ on P_ACO₂ for a particular infant. (3) The changes in alveolar gases are linear during apnea. The data are consistent with the idea that each infant has an optimum narrow range of P_ACO₂ and P_AO₂ values in which apnea occurs.

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Rate of disappearance of labeled carbon dioxide from the lungs of humans during breath holding: a method for studying the dynamics of pulmonary CO2 exchange

Cited by 35 publications

References 35 publications

A deep breath method for noninvasive estimation of cardiopulmonary parameters

A deep breath method for noninvasive estimation of cardiopulmonary parameters

A method for estimating contact time of red blood cells through lung capillary from O2 and CO2 concentrations in rebreathing air in man.

Profile of Alveolar Gases during Periodic and Regular Breathing in Preterm Infants

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