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Yamaguchi K, Tsuji T, Aoshiba K, Nakamura H, Abe S. Can DL NO/DL CO ratio offset prejudicial effects of functional heterogeneities in acinar regions? Respir Physiol Neurobiol 2020; 282:103517. [PMID: 32805419 DOI: 10.1016/j.resp.2020.103517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Accepted: 08/03/2020] [Indexed: 02/07/2023]
Abstract
OBJECTIVES (1) To establish the general equation that describes relationship of DMCO/Vc versus DLNO/DLCO under conditions with no functional heterogeneities. (2) To examine the effects of functional heterogeneities, including parallel and series (stratified) heterogeneities, on DLNO/DLCO. RESULTS AND DISCUSSIONS (1) Given that "true" θNO in pulmonary capillaries is represented by surface absorption-related θNO, relationship between DMCO/Vc and DLNO/DLCO does not differ significantly from that obtained on premise of infinite θNO. DLNO/DLCO decided physiologically may mirror morphometric DMCO/Vc actually working for gas exchange but not "total" morphometric ratio of DMCO/Vc. (2) There are three parallel heterogeneities that affect diffusing capacity (D)-related parameters. Of them, only the heterogeneity of D/VA, where VA is alveolar volume, underestimates DLCO and DLNO. DLNO/DLCO does not alleviate negative impact of D/VA heterogeneity, indicating that DMCO/Vc estimated from DLNO/DLCO does not mirror "true" morphometric DMCO/Vc in diseased lungs with D/VA maldistribution. (3) Stratified heterogeneity underrates morphometric DMCO, DMNO, and DMNO/DMCO maximally by 1.4 %, 2.8 %, and 1.4 %, respectively, under conditions similar to single-breath D measurements, suggesting that effect of stratified heterogeneity on D measures is no longer needed to be considered in normal subjects but may be in patients having lung diseases with destructive lesions of acinar structures.
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Affiliation(s)
- Kazuhiro Yamaguchi
- Department of Respiratory Medicine, Tokyo Medical University, Tokyo 160-0023, Japan.
| | - Takao Tsuji
- Department of Respiratory Medicine, Tokyo Medical University, Tokyo 160-0023, Japan
| | - Kazutetsu Aoshiba
- Department of Respiratory Medicine, Tokyo Medical University Ibaraki Medical Center, Ibaraki 300-0395, Japan
| | - Hiroyuki Nakamura
- Department of Respiratory Medicine, Tokyo Medical University Ibaraki Medical Center, Ibaraki 300-0395, Japan
| | - Shinji Abe
- Department of Respiratory Medicine, Tokyo Medical University, Tokyo 160-0023, Japan
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Yamaguchi K, Tsuji T, Aoshiba K, Nakamura H, Abe S. Anatomical backgrounds on gas exchange parameters in the lung. World J Respirol 2019; 9:8-28. [DOI: 10.5320/wjr.v9.i2.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 11/11/2018] [Accepted: 12/17/2018] [Indexed: 02/06/2023] Open
Affiliation(s)
- Kazuhiro Yamaguchi
- Department of Respiratory Medicine, Tokyo Medical University, Tokyo 160-0023, Japan
| | - Takao Tsuji
- Department of Respiratory Medicine, Tokyo Medical University, Tokyo 160-0023, Japan
| | - Kazutetsu Aoshiba
- Department of Respiratory Medicine, Tokyo Medical University, Ibaraki Medical Center, Ibaraki 300-0395, Japan
| | - Hiroyuki Nakamura
- Department of Respiratory Medicine, Tokyo Medical University, Ibaraki Medical Center, Ibaraki 300-0395, Japan
| | - Shinji Abe
- Department of Respiratory Medicine, Tokyo Medical University, Tokyo 160-0023, Japan
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Van Iterson EH, Smith JR, Olson TP. Alveolar Air and O 2 Uptake During Exercise in Patients With Heart Failure. J Card Fail 2018; 24:695-705. [PMID: 30103021 DOI: 10.1016/j.cardfail.2018.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 07/01/2018] [Accepted: 08/02/2018] [Indexed: 12/15/2022]
Abstract
BACKGROUND Peak exercise pulmonary oxygen uptake (V̇O2) is a primary marker of prognosis in heart failure (HF). The pathophysiology of impaired peak V̇O2 is unclear in patients. To what extent alveolar airway function affects V̇O2 during cardiopulmonary exercise testing (CPET) has not been fully elucidated. This study aimed to describe how changes in alveolar ventilation (V̇A), volume (VA), and related parameters couple with exercise V̇O2 in HF. METHODS AND RESULTS A total of 35 patients with HF (left ventricular ejection fraction 20 ± 6%, age 53 ± 7 y) participated in CPET with breath-to-breath measurements of ventilation and gas exchange. At rest, 20 W, and peak exercise, arterial CO2 tension was measured via radial arterial catheterization and used in alveolar equations to derive V̇A and VA. Resting lung diffusion capacity for carbon monoxide (DLCO) was assessed and indexed to VA for each time point. Resting R2 between V̇O2 and V̇A, VA, DLCO, and DLCO/VA was 0.68, 0.18, 0.20, and 0.07, respectively (all P < .05 except DLCO/VA). 20 W R2 between V̇O2 and V̇A, VA, DLCO, and DLCO/VA was 0.64, 0.32, 0.07, and 0.18 (all P < .05 except DLCO). Peak exercise R2 between V̇O2 and V̇A, VA, DLCO, and DLCO/VA was 0.55, 0.31, 0.34, and 0.06 (all P < .05 except DLCO/VA). CONCLUSIONS These data suggest that alveolar airway function that is not exclusively related to effects caused by localized lung diffusivity affects exercise V̇O2 in moderate-to-severe HF.
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Affiliation(s)
- Erik H Van Iterson
- Preventive Cardiology and Cardiac Rehabilitation Section, Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, Cleveland, Ohio; Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.
| | - Joshua R Smith
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
| | - Thomas P Olson
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
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Wang T, Hicks JW. An integrative model to predict maximum O2 uptake in animals with central vascular shunts. ZOOLOGY 2006; 105:45-53. [PMID: 16351855 DOI: 10.1078/0944-2006-00043] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2001] [Accepted: 12/01/2001] [Indexed: 11/18/2022]
Abstract
Gas exchange in the tissues and lungs is accurately described by simple equations, and mathematical models of O(2) transport play a paramount role in the conceptual understanding of respiratory physiology. In the present paper, we review an integrative approach to describe maximum oxygen uptake in animals with tidally ventilated lungs. Further, we expand the analysis by including a central vascular shunt compartment to mimic the cardiovascular anatomy of embryonic birds and mammals as well as many ectothermic vertebrates. Finally, we predict the effects of right-to-left and left-to-right cardiac shunts on maximal oxygen uptake and present a new hypothesis that relates the interaction of metabolic rates and central shunts in air breathing ectothermic vertebrates.
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Affiliation(s)
- Tobias Wang
- Department of Zoophysiology, Aarhus University, Denmark.
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Votion D, Ghafir Y, Vandenput S, Duvivier DH, Art T, Lekeux P. Analysis of scintigraphical lung images before and after treatment of horses suffering from chronic pulmonary disease. Vet Rec 1999; 144:232-6. [PMID: 10189675 DOI: 10.1136/vr.144.9.232] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Scintigraphical analysis of the ratio of inhalation (I) to perfusion (Q) was designed to determine whether chronic pulmonary disease in horses induced mismatches in I/Q and to assess whether medical treatment would restore an I/Q distribution pattern identical to that of control horses. In addition, the results of the I/Q analysis were correlated with the alveolar-arterial PO2 difference (AaDO2). The I/Q matching found in a group of control horses was compared with the I/Q analysis of a group of diseased horses before and after their clinical signs had been treated. The analysis indicated that there was mismatching between I and Q before they were treated. The treatment improved the diseased horses, pulmonary function but there was still heterogeneity in the I/Q distribution after they had been treated. The I/Q analysis parameters were well correlated with the ratio of ventilation (VA) and pulmonary blood flow (Q), evaluated by the determination of AaDO2.
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Affiliation(s)
- D Votion
- Department of Physiology, Faculty of Veterinary Medicine, University of Liège, Belgium
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Vidal Melo MF. Effect of cardiac output on pulmonary gas exchange: role of diffusion limitation with VA/Q mismatch. RESPIRATION PHYSIOLOGY 1998; 113:23-32. [PMID: 9776547 DOI: 10.1016/s0034-5687(98)00042-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We studied the effect of the interaction between diffusion limitation and alveolar ventilation to perfusion ratio (VA/Q) mismatch in the relation between blood gas partial pressures and cardiac output (Q). The analysis was based on a mathematical model of gas exchange involving two exchanging compartments and a right to left shunt. A system of equations describing alveolar-arterial mass conservation for O2, CO2 and N2 and Bohr integration for O2 and CO2 was interactively solved to find sets of alveolar and blood gas partial pressures fitting input data. Simulations used values compatible with patients in respiratory failure and neonate piglets. Association of (VA/Q) mismatch and diffusion impairment limited the increase of PaO2 with Q. A maximum in the PaO2 vs. Q curve can be attained, further Q increases lead to reductions in PaO2. The effect was accentuated by increasing (VA/Q) and diffusion to perfusion heterogeneity. Combination of (VA/Q) mismatch and diffusion limitation was synergistic leading to greater reductions in PaO2 than expected from simple addition of their independent influences. The findings are compatible with experimental data.
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Affiliation(s)
- M F Vidal Melo
- Department of Anesthesia and Critical Care, Massachusetts General Hospital, Boston 02114, USA.
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BJURE J, SOEDERHOLM B, WIDIMSKY J. CARDIOPULMONARY FUNCTION STUDIES IN WORKERS DEALING WITH ASBESTOS AND GLASSWOOL. Thorax 1996; 19:22-7. [PMID: 14105880 PMCID: PMC1018795 DOI: 10.1136/thx.19.1.22] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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JOHNSON RL, TAYLOR HF, DEGRAFF AC. FUNCTIONAL SIGNIFICANCE OF A LOW PULMONARY DIFFUSING CAPACITY FOR CARBON MONOXIDE. J Clin Invest 1996; 44:789-800. [PMID: 14276136 PMCID: PMC292555 DOI: 10.1172/jci105191] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Yamaguchi K, Mori M, Kawai A, Takasugi T, Asano K, Oyamada Y, Aoki T, Fujita H, Suzuki Y, Yamasawa F. Ventilation-perfusion inequality and diffusion impairment in acutely injured lungs. RESPIRATION PHYSIOLOGY 1994; 98:165-177. [PMID: 7817048 DOI: 10.1016/0034-5687(94)00061-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
To assess the significant role of diffusion impairment and its unequal distribution in acutely injured lungs with alveolar flooding, oleic acid was intravenously injected into twenty-five mongrel dogs. The animals were divided into two groups, A and B. 0.1% CO in air was delivered, as an inspired gas, to the animals of group A. Simultaneously, saline containing a trace amount of six foreign inert gases was infused through a peripheral vein. While allowing the animals in group B to breathe air, saline containing ethylene, acetylene and freon 22 was infused. After injection of oleic acid, group A revealed increase in intrapulmonary shunt accompanied by a marked broadening of ventilation-perfusion (VA/Q) and diffusing capacity-perfusion (G/Q) distributions. A considerable amount of total cardiac output was received by the lung areas with low G/Q ratios where significant diffusion limitation was predicted to occur. Group B showed that excretion of freon 22 (gas with lower diffusivity) in injured lungs was considerably distorted as compared to those of ethylene and acetylene (gases with higher diffusivities), again ascertaining the importance of diffusion limitation in lungs with exudate in alveolar regions.
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Affiliation(s)
- K Yamaguchi
- Department of Medicine, School of Medicine, Keio University, Tokyo, Japan
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Piiper J. Alveolar-capillary gas transfer in lungs: development of concepts and current state. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1994; 345:7-14. [PMID: 8079776 DOI: 10.1007/978-1-4615-2468-7_2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Progress in research on pulmonary gas exchange, with special reference to the contribution of Gerhard Thews and associates, is reviewed. In particular, the following aspects are considered. (1) Oxygen transfer kinetics of red blood cells. Recent measurements, particularly on red blood cells in thin blood films, yield more rapid equilibration kinetics than previously recorded. A reevaluation of the roles of diffusion and chemical reaction in alveolar O2 uptake may become necessary. (2) Gas exchange in functionally inhomogeneous lungs. Besides the classical ventilation/perfusion (VA/Q) inequality, a variation of the diffusing capacity-to-perfusion ratio (DL/Q) appears to be of importance. The combination of VA/Q and DL 1Q inequalities may lead to a better understanding of alveolar gas exchange, particularly in diseased lungs. (3) Pulmonary diffusing capacity (DL) for oxygen. The rebreathing technique, which strongly reduces the effects of inequal VA/Q distribution effects, appears to be particularly suited for measurement of overall alveolar-capillary diffusion. But neither the factors determining DL, obtained by rebreathing or other methods, nor the relationships between DL for various gases are yet fully understood.
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Affiliation(s)
- J Piiper
- Abteilung Physiologie, Max-Planck-Institut für experimentelle Medizin, Göttingen, Germany
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Piiper J. Diffusion-perfusion inhomogeneity and alveolar-arterial O2 diffusion limitation: theory. RESPIRATION PHYSIOLOGY 1992; 87:349-56. [PMID: 1604057 DOI: 10.1016/0034-5687(92)90016-p] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Unequal distribution of pulmonary O2 diffusing capacity (D) to pulmonary blood flow (Q) (D/Q heterogeneity) leads to decreased alveolar O2 exchange efficacy. It is shown on simple models that the effect increases with increasing amount of inequality and with increasing value of the equilibration index, D/(Q beta) (beta, increment in blood O2 content per partial pressure increment). This inhomogeneity effect, if not taken into account, leads to spurious increases of D in hypoxia and with elevated O2 uptake.
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Affiliation(s)
- J Piiper
- Abteilung Physiologie, Max-Planck-Institut für experimentelle Medizin, Göttingen, Germany
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Yamaguchi K, Kawai A, Mori M, Asano K, Takasugi T, Umeda A, Kawashiro T, Yokoyama T. Distribution of ventilation and of diffusing capacity to perfusion in the lung. RESPIRATION PHYSIOLOGY 1991; 86:171-187. [PMID: 1780598 DOI: 10.1016/0034-5687(91)90079-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
We developed a method for estimating the distribution of ventilation (VA) and of diffusing capacity (G) to perfusion (Q) in the lungs. We used O2, CO2 and CO together with six inert gases of widely differing solubility and assumed that mass transfer efficiency of each gas in a gas exchange unit is limited by both VA/Q and G/Q ratios. The underlying lung model comprised 20 units along both the VA/Q and G/Q axes. Using numerical analysis, we transformed the data into a virtually continuous distribution of Q in the VA/Q-G/Q field. We tested the precision of the numerical procedure by examining the recovery of various artificial distributions, and found that distributions with up to two modes could be recovered with reasonable accuracy. Analytical results from 15 patients with interstitial pneumonia of unknown etiology (IPF) revealed the following features. (1) In an early disease stage, most of the lung was operating in the range of normal VA/Q, without a significant contribution of diffusion limitation. (2) An advanced stage of the disease exhibited a widening of VA/Q distribution and either broad unimodal or bimodal distribution of G/Q, extending to G/Q below 10(-3) ml (STPD)/(ml.Torr) with diffusion-limited O2 exchange. (3) Severe diffusion limitation causing disequilibrium of inert gas across the blood-gas barrier was observed in three (far advanced fibrosis; active interstitial inflammation) out of 15 patients. These findings suggest that inhomogeneity of G/Q does exist and may play an appreciable role in causing impairment of gas exchange in patients with interstitial pneumonia.
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Affiliation(s)
- K Yamaguchi
- Department of Medicine, School of Medicine, Keio University, Tokyo, Japan
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Yamaguchi K, Kawai A, Mori M, Asano K, Takasugi T, Umeda A, Yokoyama T. Continuous distributions of ventilation and gas conductance to perfusion in the lungs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1990; 277:625-36. [PMID: 1965763 DOI: 10.1007/978-1-4684-8181-5_71] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Theoretical analysis and experimental observations were conducted to establish a method allowing to demonstrate the characteristics of distribution of ventilation (VA) as well as of diffusive conductance (G) to perfusion (Q) in the lungs. O2, CO2 and CO binding to hemoglobin molecules within the erythrocyte together with six inert gases including SF6, ethane, cyclopropane, halothane, diethyl ether and acetone, of varied solubility in blood and different diffusivity in lung tissue, were used as indicator gases. 15 patients with interstitial pneumonia of unknown etiology, placed in the supine position, were given a mixture of 21% O2 and 0.1% CO in N2 as the inspired gas and saline containing appropriate amount of the six inert gases was infused via an antecubital vein. After a steady state was established, the expired gas was collected and the samples of both arterial and mixed venous blood were simultaneously taken through catheters inserted into the femoral and pulmonary artery. The concentrations of the indicator gases in the samples were measured by gas chromatography, with electrodes or with the Scholander gas analyzer. Assuming that the mass transfer efficiency of a given indicator gas at each gas exchange unit would be limited by VA/Q and G/Q ratios, the data obtained from the human subjects were analyzed in terms of a lung model having 20 units along the VA/Q and G/Q axes, respectively. The numerical analysis including the procedure of simultaneous Bohr integration for O2, CO2 and CO in a pulmonary capillary and the method of weighted least-squares combined with constrained optimization permitted the data to be transformed into a virtually continuous distribution of Q against VA/Q and G/Q axes. The numerical procedure was strictly tested using various artificial distributions of VA/Q and G/Q ratios, showing that it could characterize the distributions containing up to at least two modes on VA/Q-G/Q field with a substantial accuracy. Analytical results estimated from the patients with interstitial lung disease revealed the following features. (1) There appears to be bimodal distribution of Q along G/Q axis extending to relatively low G/Q less than 10(-3) ml(STPD)/(ml.Torr), which may limit O2 exchange between alveolar gas and capillary blood. This area of low G/Q receives 10% of total Q. (2) Severe diffusion limitation causing disequilibrium of the inert gas across the blood-gas barrier is solely observed in 2 out of 15 patients and an amount of Q associated with this phenomenon is very small (below 1%).(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- K Yamaguchi
- Department of Medicine, School of Medicine, Keio University, Tokyo, Japan
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Powell FL, Hempleman SC. Comparative physiology of oxygen transfer in lungs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1988; 227:53-65. [PMID: 3289323 DOI: 10.1007/978-1-4684-5481-9_5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- F L Powell
- Department of Medicine, University of California, San Diego, La Jolla 92093
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Berk JL, Hagen JF, Koo R, Beyer W, Dochat GR, Rupright M, Nomoto S. Pulmonary insufficiency caused by epinephrine. Ann Surg 1973; 178:423-35. [PMID: 4743864 PMCID: PMC1355675 DOI: 10.1097/00000658-197310000-00005] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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22
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Moran F, Pack AI. Measurement of the Gas-Exchanging Function of the Lung. Proc R Soc Med 1973. [DOI: 10.1177/003591577306601006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
| | - A I Pack
- Centre for Respiratory Investigation, Royal Infirmary, Glasgow C4
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Cross CE, Gong H, Kurpershoek CJ, Gillespie JR, Hyde RW. Alterations in distribution of blood flow to the lung's diffusion surfaces during exercise. J Clin Invest 1973; 52:414-21. [PMID: 4683880 PMCID: PMC302271 DOI: 10.1172/jci107198] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
We measured simultaneously, by single breath methods, pulmonary capillary blood flow (Q(c)), carbon monoxide diffusing capacity (DL(CO)), and isotopic oxygen ((18)O(18)O) diffusing capacity (DL(18) (O2)) in five normal males during conditions of rest and moderate exercise at mixed venous O(2) tensions (PO(2) 33-44 mm Hg). During moderate exercise at a work load of 100 W. pulmonary capillary blood flow increased from 6.9+/-1.5 to 12.9+/-3.4 min(-1) and DL(18) (O2) increased from 25+/-4 to 43+/-3 ml.min(-1).mm Hg(-1), whereas DL(CO) showed no significant change (45+/-5 to 49+/-10 ml.min(-1).mm Hg(-1)). DL(18) (O2) increased proportionally to Q(c) (r = 0.74), where DL(CO) did not (r = 0.08). The greater increase in DL(18) (O2) during exercise can be explained by a more homogeneous diffusion/perfusion (DL(O2)/Q(c)) distribution in the individual respiratory exchange units during exercise. This improved distribution of DL(O2)/Q(c) acts to help prevent an increase in alveolar-arterial O(2) tension difference from developing despite the decrease in pulmonary erythrocyte transit times that occur during exercise. The insignificant rise in DL(CO) with exercise under these hypoxic breathholding conditions may result from pulmonary vasomotor responses to short-term hypoxia or from relative insensitivity of DL(CO) to moderate levels of exercise.
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Chinet A, Micheli JL, Haab P. Inhomogeneity effects on O 2 and CO pulmonary diffusing capacity estimates by steady-state methods. Theory. RESPIRATION PHYSIOLOGY 1971; 13:1-22. [PMID: 5112827 DOI: 10.1016/0034-5687(71)90061-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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Saidel GM, Militano TC, Chester EH. Pulmonary gas transport characterization by a dynamic model. RESPIRATION PHYSIOLOGY 1971; 12:305-28. [PMID: 5136021 DOI: 10.1016/0034-5687(71)90073-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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Piiper J, Huch A, Kötter D, Herbst R. Pulmonary diffusing capacity at basal and increased O2 uptake levels in anesthetized dogs. RESPIRATION PHYSIOLOGY 1969; 6:219-32. [PMID: 5773390 DOI: 10.1016/0034-5687(69)90060-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Piiper J. Apparent increase of the O2 diffusing capacity with increased O2 uptake in inhomogeneous lungs: theory. RESPIRATION PHYSIOLOGY 1969; 6:209-18. [PMID: 5773389 DOI: 10.1016/0034-5687(69)90059-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Thews G, Vogel HR. [The distribution analysis of ventilation, perfusion, and O2 diffusing capacity in the lung, through concentration changes for 3 inspiratory gases. I. Theory]. Pflugers Arch 1968; 303:195-205. [PMID: 5693721 DOI: 10.1007/bf01890900] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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31
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Hyde RW, Rynes R, Power GG, Nairn J. Determination of distribution of diffusing capacity in relation to blood flow in the human lung. J Clin Invest 1967; 46:463-74. [PMID: 6023780 PMCID: PMC297067 DOI: 10.1172/jci105548] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
A method for appraising the distribution of diffusing capacity of the lungs (D(L)) in relationship to pulmonary capillary blood flow ([unk]Q(C)) in normal human subjects was derived from measurements of oxygen diffusing capacity (D(LO2)) and carbon monoxide diffusing capacity (D(LCO)) performed during breath holding. This method utilizes the fact that the observed D(LO2) is considerably reduced in value if uneven distribution of D(L) with respect to [unk]Q(C) (uneven D(L)/[unk]Q(C)) is present. In contrast, D(LCO) is barely affected by uneven D(L)/[unk]Q(C), and from its measured value one can calculate the value D(LO2) would have if no uneven D(L)/[unk]Q(C) were present (true D(LO2)). Once observed D(LO2) and true D(LO2) are known, the degree of uneven D(L)/[unk]Q(C) in the lung can be calculated. In five normal, resting, sitting subjects average values for true D(LO2) were 57 ml per (minute x mm Hg), and the directly measured D(LO2) was 33 ml per (minute x mm Hg). These values could be explained if one-half of total [unk]Q(C) were distributed to approximately 15% of total D(L). These measurements did not permit the determination of the alveolar to end capillary O(2) gradient, but calculations demonstrate that an important factor in determining its size may be the pattern of uneven D(L)/[unk]Q(C) present in the lungs. Estimations of the alveolar-end capillary O(2) gradient from measurements of D(LCO) or D(LO2) that do not take into account uneven D(L)/[unk]Q(C) may underestimate its size.
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Mellemgaard K. The alveolar-arterial oxygen difference: its size and components in normal man. ACTA PHYSIOLOGICA SCANDINAVICA 1966; 67:10-20. [PMID: 5963295 DOI: 10.1111/j.1748-1716.1966.tb03281.x] [Citation(s) in RCA: 170] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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Der Einflu� der W�rmetachypnoe des Hundes auf die alveol�r-arterielle O2-Spannungsdifferenz (AaD). Pflugers Arch 1963. [DOI: 10.1007/bf00363491] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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