Saturation kinetics for steady-state pulmonary CO transfer

1977 ◽  
Vol 43 (5) ◽  
pp. 880-884 ◽  
Author(s):  
C. Mendoza ◽  
H. Peavy ◽  
B. Burns ◽  
G. Gurtner
Keyword(s):  
Carbon Monoxide ◽  
Steady State ◽  
Reaction Rate ◽  
Back Pressure ◽  
Diffusing Capacity ◽  
Pulmonary Capillary ◽  
Capillary Membrane ◽  
Saturation Kinetics ◽  
Co Concentration ◽  
Alveolar Capillary

Steady-state diffusing capacity of the lungs for carbon monoxide (DLCO) was measured in 13 anesthetized, paralyzed dogs ventilated at constant tidal volume and rate, using four different inspired CO levels (190, 600, 1,110, and 2,000 ppm). DLCO increased and reached a maximum as the inspired CO level was raised from 190 to 600 ppm. Further increases in inspired CO concentration were accompanied by a decrease in inspired CO concentration were accompanied by a decrease in DLCO. CO dead space and Pao2 remained constant at all inspired O2 levels. In some experiments a second set of measurements was made, the results of which were similar to those of the first set. The results cannot be explained by changes in CO back pressure, pulmonary capillary volume, or reaction rate of CO with hemoglobin, but can be explained if there is carrier-mediated CO transport in the alveolar capillary membrane.

Effect of negative intra-alveolar pressure on pulmonary diffusing capacity

1960 ◽  
Vol 15 (3) ◽  
pp. 372-376 ◽  
Author(s):  
J. E. Cotes ◽  
D. P. Snidal ◽  
R. H. Shepard
Keyword(s):  
Carbon Monoxide ◽  
Venous Pressure ◽  
Capillary Blood ◽  
Breath Holding ◽  
Diffusing Capacity ◽  
Alveolar Pressure ◽  
Holding Period ◽  
Capillary Membrane ◽  
Capillary Blood Volume ◽  
Alveolar Capillary

In one of two subjects studied in detail, using 0.1% carbon monoxide in the test gas and a 10-second breath-holding period, the alveolar capillary blood volume (Vc) was found to increase by nearly 100% when the intra-alveolar pressure was made negative during breath holding. This was accompanied by a reduction in venous pressure in the forearm. In both subjects Vc was increased on exercise. The diffusing capacity of the alveolar capillary membrane (Dm) remained relatively constant in spite of large changes in Vc. The findings suggest that stationary blood is present in some alveolar capillaries at rest. The implications of this finding and a likely mechanism for the increase in Vc with negative pressure are discussed. xsSubmitted on September 14, 1959

Pulmonary diffusing capacity and capillary blood volume in normal and anemic dogs

1965 ◽  
Vol 20 (1) ◽  
pp. 113-116 ◽  
Author(s):  
Denise Jouasset-Strieder ◽  
John M. Cahill ◽  
John J. Byrne ◽  
Edward A. Gaensler
Keyword(s):  
Blood Volume ◽  
Capillary Blood ◽  
Diffusing Capacity ◽  
Alveolar Volume ◽  
Arterial Blood ◽  
Pulmonary Capillary ◽  
Capillary Membrane ◽  
Capillary Blood Volume ◽  
The Mean ◽  
Alveolar Capillary

The CO diffusing capacity (Dl) was measured by the single-breath method in eight anesthetized dogs. Pulmonary capillary blood volume (Vc) and membrane diffusing capacity (Dm) were determined in six animals by the method of Roughton and Forster. The studies were repeated after anemia had been induced by replacing whole blood with plasma. Large dogs were selected with a mean body weight of 29 kg and a mean alveolar volume of 2,020 ml (STPD) during tests. The mean arterial blood Hb decreased from 14.3 to 6.6 g/100 ml, the mean Dl from 27 to 12 ml/min mm Hg, and the mean Dm from 100 to 47 ml/min mm Hg. Vc averaged 67 ml in the control state and was not significantly changed during anemia. Reductions in Dl and Dm during anemia were proportional to the fall in blood Hb. Both Dl and Dm in all dogs, normal and anemic, were proportional to the volume of red blood cells in the lung capillaries (Vrbc). These results suggest that Vrbc might be an estimate of the useful area of the alveolar-capillary membrane while Dm/Vrbc should vary with changes in its thickness. The latter was not altered by anemia. alveolar capillary membrane; pulmonary membrane; diffusing capacity; pulmonary capillary RBC volume; pulmonary diffusion pathway; carbon monoxide Submitted on March 2, 1964

Effects of anemia and hemorrhagic shock on pulmonary diffusion in the dog lung

1963 ◽  
Vol 18 (1) ◽  
pp. 123-128 ◽  
Author(s):  
Benjamin Burrows ◽  
Albert H. Niden
Keyword(s):  
Carbon Monoxide ◽  
Blood Flow ◽  
Blood Cell ◽  
Hemorrhagic Shock ◽  
Red Blood Cell ◽  
Lung Volume ◽  
Diffusing Capacity ◽  
Pulmonary Diffusing Capacity ◽  
Capillary Membrane ◽  
Alveolar Capillary

Hemorrhagic shock induced a marked fall in the pulmonary diffusing capacity for carbon monoxide in the dog (Dl) and produced marked nonuniformity of Dl/Va ratios throughout the lung as assessed by the “equilibration technique”. Difficulties in calculating over-all Dl under these conditions are discussed. Induced anemia also produced a fall in Dl, but little change in the uniformity of Dl/Va ratios was noted. In isolated perfused dog lungs where blood flow, pulmonary vascular pressures, lung volume, and ventilation were maintained constant, Dl was found to be proportional to hematocrit, suggesting either: 1) that virtually all resistance to CO diffusion is in the erythrocyte or 2) that the apparent diffusing capacity of the alveolar-capillary membrane is dependent upon hematocrit, carbon monoxide transfer being reduced across portions of membrane which are some distance from a red blood cell. Submitted on January 12, 1962

scholarly journals Simultaneous Measurement of Lung Diffusing Capacity and Pulmonary Hemodynamics Reveals Exertional Alveolar‐Capillary Dysfunction in Heart Failure With Preserved Ejection Fraction

2021 ◽  
Author(s):  
Caitlin C. Fermoyle ◽  
Glenn M. Stewart ◽  
Barry A. Borlaug ◽  
Bruce D. Johnson
Keyword(s):  
Heart Failure ◽  
Maximal Exercise ◽  
Arterial Compliance ◽  
Preserved Ejection Fraction ◽  
Diffusing Capacity ◽  
Pulmonary Capillary ◽  
Capillary Membrane ◽  
Pulmonary Arterial ◽  
Wedge Pressure ◽  
Alveolar Capillary

Background Hemodynamic perturbations in heart failure with preserved ejection fraction (HFpEF) may alter the distribution of blood in the lungs, impair gas transfer from the alveoli into the pulmonary capillaries, and reduce lung diffusing capacity. We hypothesized that impairments in lung diffusing capacity for carbon monoxide (DL CO ) in HFpEF would be associated with high mean pulmonary capillary wedge pressures during exercise. Methods and Results Rebreathe DL CO and invasive hemodynamics were measured simultaneously during exercise in patients with exertional dyspnea. Pulmonary pressure waveforms and breath‐by‐breath pulmonary gas exchange were recorded at rest, 20 W, and symptom‐limited maximal exercise. Patients with HFpEF (n=20; 15 women, aged 65±11 years, body mass index 36±8 kg/m 2 ) achieved a lower symptom‐limited maximal workload (52±27 W versus 106±42 W) compared with controls with noncardiac dyspnea (n=10; 7 women, aged 55±10 years, body mass index 30±5 kg/m 2 ). DL CO was lower in patients with HFpEF compared with controls at rest (DL CO 10.4±2.9 mL/min per mm Hg versus 16.4±6.9 mL/min per mm Hg, P <0.01) and symptom‐limited maximal exercise (DL CO 14.6±4.7 mL/min per mm Hg versus 23.8±10.8 mL/min per mm Hg, P <0.01) because of a lower alveolar‐capillary membrane conductance in HFpEF (rest 16.8±6.6 mL/min per mm Hg versus 28.4±11.8 mL/min per mm Hg, P <0.01; symptom‐limited maximal exercise 25.0±6.7 mL/min per mm Hg versus 45.5±22.2 mL/min per mm Hg, P <0.01). DL CO was lower in HFpEF for a given mean pulmonary artery pressure, mean pulmonary capillary wedge pressure, pulmonary arterial compliance, and transpulmonary gradient. Conclusions Lung diffusing capacity is lower at rest and during exercise in HFpEF due to impaired gas conductance across the alveolar‐capillary membrane. DL CO is impaired for a given pulmonary capillary wedge pressure and pulmonary arterial compliance. These data provide new insight into the complex relationships between hemodynamic perturbations and gas exchange abnormalities in HFpEF.

scholarly journals Relationship Between Exhaled Na+ and the Diffusion Capacity of the Lungs for Carbon Monoxide (DLCO) and Alveolar‐Capillary Membrane Conductance in Healthy Humans

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Courtney M. Wheatley ◽  
Nicholas A. Cassuto ◽  
William T. Foxx‐Lupo ◽  
Eric C. Wong ◽  
Nicholas A. Delamere ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Membrane Conductance ◽  
Diffusion Capacity ◽  
Healthy Humans ◽  
Capillary Membrane ◽  
Alveolar Capillary

The Two Doctors Fick

2011 ◽  
pp. 94-100
Author(s):  
James R. Munis
Keyword(s):  
Cardiac Output ◽  
Steady State ◽  
Transfer Rate ◽  
Dialysis Membrane ◽  
Solute Transfer ◽  
Fick Principle ◽  
Capillary Membrane ◽  
The Difference ◽  
Physical Laws ◽  
Alveolar Capillary

We often confuse the ‘Fick principle’ with ‘Fick's law of diffusion.’ They are not the same. Ironically, Fick borrowed heavily from already known physical laws when he first described both his law of diffusion and his principle. Borrowing from Ohm's law of electricity, Fick applied concepts of diffusion and transfer across a resistance to formulate a law of diffusion that could be applied to gas or solute transfer across a membrane. Whether we are talking about transfer across the alveolar-capillary membrane or across a dialysis membrane, the concept is the same. The concept is similar to electricity—you have a transfer rate, resistance, and a gradient. Now let's consider the Fick principle. On the basis of another physical law he understood that, in the steady state, the difference between the amount of oxygen going into a tissue bed minus that leaving the tissue bed must be equal to the oxygen consumed. With a little reworking, this became the Fick principle: Cardiac output = O2 consumption / (arterial O2 - venous O2).

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