Size of Gas Exchange Vessels in the Lung *

Sackner, Marvin A.; Feisal, Khalil A.; Karsch, Daniel N.

doi:10.1172/jci105058

Cited by 17 publications

(10 citation statements)

References 16 publications

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“…First, according to the molecular weights of CO and *CO2 and their relative solubilities in water, DMC02 is 25-fold greater than DMco. Second, Vc for CO2 may be larger than Vc for CO but recent measurements of 02 vs. ether exchanges between the pulmonary vessels and the alveolar gas imply that this difference can be at the most 20% (31 (33). Figure 8 order to improve arterial blood oxygenation and lower the arterial Pco2 (34,35).…”

Section: Discussionmentioning

confidence: 99%

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

Hyde¹,

Puy²,

Raub³

et al. 1968

J. Clin. Invest.

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Section: Discussionmentioning

confidence: 99%

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

Hyde¹,

Puy²,

Raub³

et al. 1968

J. Clin. Invest.

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“…Midcapillary pressure averaged 13.3 cm H2O, pulDr. Brody is a postdoctoral fellow of the National Institutes of Health.…”

mentioning

confidence: 99%

Longitudinal distribution of vascular resistance in the pulmonary arteries, capillaries, and veins

Brody¹,

Stemmler²,

DuBois³

1968

J. Clin. Invest.

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A B S T R A C T A new method has been described for measuring the pressure and resistance to blood flow in the pulmonary arteries, capillaries, and veins. Studies were performed in dog isolated lung lobes perfused at constant flow with blood from a donor dog. Pulmonary artery and vein volume and total lobar blood volume were measured by the ether plethysmograph and dyedilution techniques. The longitudinal distribution of vascular resistance was determined by analyzing the decrease in perfusion pressure caused by a bolus of low viscosity liquid introduced into the vascular inflow of the lobe.The pulmonary arteries were responsible for 46% of total lobar vascular resistance, whereas the pulmonary capillaries and veins accounted for 34 and 20% of total lobar vascular resistance respectively. Vascular resistance was 322 dynes * sec* cm-5/ml of vessel in the lobar pulmonary arteries, 112 dynes sec.cm-5/ml in the pulmonary capillaries, and 115 dynes-sec* cm5/ml in the lobar pulmonary veins. Peak vascular resistivity (resistance per milliliter of volume) was in an area 2 ml proximal to the capillary bed, but resistivity was high throughout the pulmonary arterial tree. The pulmonary arteries accounted for approximately 50% of vascular resistance upstream from the sluice point when alveolar pressure exceeded venous pressure.The method described provides the first measurements of pulmonary capillary pressure. Midcapillary pressure averaged 13.3 cm H2O, pulDr. Brody is a postdoctoral fellow of the National Institutes of Health.

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“…We can estimate the number of alveoli supplied by each vessel of this size by dividing the total number of alveoli in the lung by the total number of 30-m arterioles. Data for this calculation are available for dog lungs, for which we calculate a ratio of 750 alveoli per 30-m arteriole (13,14). We assume a similar ratio for rat lungs.…”

Section: Effect Of Parenchyma On Particle Distributionmentioning

confidence: 99%

Perfusion heterogeneity in rat lungs assessed from the distribution of 4-μm-diameter latex particles

Conhaim

Watson

Heisey

et al. 2003

Journal of Applied Physiology

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sion heterogeneity in rat lungs assessed from the distribution of 4-m-diameter latex particles. J Appl Physiol 94: 420-428, 2003. First published October 11, 2002 10.1152/japplphysiol. 00700.2002.-Pulmonary vascular perfusion has been shown to follow a fractal distribution down to a resolution of 0.5 cm 3 (5E11 m 3 ). We wanted to know whether this distribution continued down to tissue volumes equivalent to that of an alveolus (2E5 m 3 ). To investigate this, we used confocal microscopy to analyze the spatial distribution of 4-m-diameter fluorescent latex particles trapped within rat lung microvessels. Particle distributions were analyzed in tissue volumes that ranged from 1.7E2 to 2.8E8 m 3 . The analysis resulted in fractal plots that consisted of two slopes. The left slope, encompassing tissue volumes less than 7E5 m 3 , had a fractal dimension of 1.50 Ϯ 0.03 (random distribution). The right slope, encompassing tissue volumes greater than 7E5 m 3 , had a fractal dimension of 1.29 Ϯ 0.04 (nonrandom distribution). The break point at 7E5 m 3 corresponds closely to a tissue volume equivalent to that of one alveolus. We conclude that perfusion distribution is random at tissue volumes less than that of an alveolus and nonrandom at tissue volumes greater than that of an alveolus. alveolar perfusion; fluorescent microspheres; fractal analysis; pulmonary blood flow FRACTAL ANALYSIS HAS BEEN used extensively to analyze the distribution of perfusion throughout the lung (3). The method is to infuse 15-m-diameter fluorescent latex particles into the pulmonary circulation and then count the number of trapped particles in blocks of frozen or air-dried lungs (15). The blocks, which range in size from 0.5 mm 3 to 2 cm 3 , are grouped mathematically to allow particle counts to be obtained in successive volumes of tissue that range from single tissue blocks up to groups of blocks on the scale of the whole lung (4). For groups of each volume, the mean and SD of the particle counts are calculated for the blocks that compose the group. A fractal plot is assembled by plotting the log of the coefficient of variation (CV; SD/mean) of the group count against the log of the group tissue volume. When this is done for groups of all volumes, it produces a linear plot that shows that the CV of the particle count increases as the group tissue volume decreases. The linearity of such plots is considered to be evidence of a fractal system, which means that perfusion distribution within the lung follows a fractal pattern. Fractals are complex geometric shapes that exhibit a scale-independent property of self-similarity such that the smallest part, no matter how highly magnified, resembles the whole (11). Using this approach, Glenny and colleagues (4) showed that pulmonary perfusion distribution remained fractal down to a tissue volume of 0.5 cm 3 (5E11 m 3 ).It is interesting to speculate whether or not this pattern continues down to the level of the alveolus. An alveolus with a diameter of 75 m has a volume of 2.2E5 m 3 , but present methods...

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Size of Gas Exchange Vessels in the Lung *

Cited by 17 publications

References 16 publications

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

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

Longitudinal distribution of vascular resistance in the pulmonary arteries, capillaries, and veins

Perfusion heterogeneity in rat lungs assessed from the distribution of 4-μm-diameter latex particles

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