The effect of age, body size and lung volume change on alveolar‐capillary permeability and diffusing capacity in man

McGrath, Margaret W.; Thomson, M. L.

doi:10.1113/jphysiol.1959.sp006212

Cited by 168 publications

(74 citation statements)

References 14 publications

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“…Figure 1 shows that KCO and TL,CO are functions of alveolar expansion [5], cardiac output [8], and haemoglobin concentration [9]. The extensive studies of Stam et al [5] have emphasized that with a reduction in alveolar expansion down to 50% TLC the rise of KCO is linear, although earlier studies [4,10] found a steeper rise at VA v50% VA,max. Despite this increase in KCO, the product KCO6VA (i.e TL,CO) falls as VA declines.…”

Section: Within Individualsmentioning

confidence: 86%

“…The variation in KCO with VA in normal subjects has been investigated extensively since 1959 [4]; in 1994, Stam et al [5] suggested that in restrictive lung disease values of TL,CO and KCO should be compared with reference values both at the patient's predicted total lung capacity (TLC) and at the lung volume equal to the patient's actual TLC; this suggestion has been endorsed subsequently [1,6,7]. The novelty in the approach of Chinn et al [1] rests on the development of reference values for TL,CO and KCO, which include a term for VA (at TLC) as well as a height term, i.e.…”

mentioning

confidence: 99%

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In defence of the carbon monoxide transfer coefficientK_CO(T_L/V_A)

Hughes

Pride²

2001

Eur Respir J

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In defence of the carbon monoxide transfer coefficient KCO (TL/VA). J.M.B.Hughes, N.B.Pride. #ERS Journals Ltd 2001. ABSTRACT: The carbon monoxide transfer factor (TL,CO) is the product of the two primary measurements during breath-holding, the CO transfer coefficient (KCO) and the alveolar volume (VA). KCO is essentially the rate constant for alveolar CO uptake (Krogh's kCO), and in healthy subjects, increases when VA is reduced by submaximal inflation, or when pulmonary blood flow increases. Recently, new reference values were proposed for clinical use which included the observed VA at full inflation; this was claimed to "eliminate the need for KCO".In this commentary, some mechanisms e.g. respiratory muscle weakness, lung resection, diffuse alveolar damage and airflow obstruction, which decrease or increase total lung capacity (TLC) are reviewed.Even when alveolar structure and function are normal, the change in KCO at a given VA varies according to the underlying pathophysiological mechanism. The advantages and disadvantages of normalizing KCO and TL,CO to predisease predicted TLC or to the patient's actual VA (using lack of expansion or loss of alveolar units models) are considered.Examination of carbon monoxide transfer coefficient and alveolar volume separately provides information on disease pathophysiology which cannot be obtained from their product, the carbon monoxide transfer factor. A few years ago, a paper in the European Respiratory Journal [1] concluded that: ". . . the use of TL/VA (the carbon monoxide (CO) transfer coefficient) cannot be justified on scientific grounds". Apart from one letter of disagreement [2], this view that TL/VA (or KCO) is a redundant and misleading measurement has not been challenged. This is surprising because measurements of TL/VA have continued to be published in respiratory journals.The single breath method for measuring CO uptake by the lung, which is used world-wide, was introduced by Krogh [3] in 1915; this measurement was termed diffusion constant. Subsequently the diffusion constant for CO was renamed the diffusing capacity (DL,CO) or the transfer factor (TL,CO), with the uptake being measured at total lung capacity (TLC). Krogh [3] pointed out that TL,CO was the product of two separate measurements, which potentially varied widely (and independently), the rate constant for CO removal from alveolar gas (called the permeability factor (kCO)) and the alveolar volume (VA).kCO is measured as the exponential decay in fractional concentration of CO over a period of breath-holding (BHT):where CO 0 and CO t are the alveolar CO concentrations at the start and finish of the breath-holding period. The units of kCO are s -1 or min -1 . The total CO transfer of the lung is calculated as:where PB and PH2O are the barometric pressure and the water vapour pressure (at 37 ‡C) which standardize for the driving pressure for CO uptake, i.e.the pressure of CO in the alveoli (PA,CO). VA is the alveolar volume measured at standard temperature and pressure, dry (STPD). In modern usag...

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Section: Within Individualsmentioning

confidence: 86%

mentioning

confidence: 99%

In defence of the carbon monoxide transfer coefficientK_CO(T_L/V_A)

Hughes

Pride²

2001

Eur Respir J

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“…As the lung inflates, DM increases (due to unfolding membranes and increasing surface area), while Vc effects are variable (due to differential stretching and flattening of alveolar and extra-alveolar capillaries) [10,[17][18][19][20][21][22][23][24]. The net effect of these changes is that DL,CO tends to increase as the lung inflates.…”

Section: Determinants Of Co Uptakementioning

confidence: 99%

“…The capacity of the lung to exchange gas across the alveolarcapillary interface is determined by its structural and functional properties [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. The structural properties include the following: lung gas volume; the path length for diffusion in the gas phase; the thickness and area of the alveolar capillary membrane; any effects of airway closure; and the volume of blood in capillaries supplying ventilated alveoli.…”

Section: Introductionmentioning

confidence: 99%

Standardisation of the single-breath determination of carbon monoxide uptake in the lung

MacIntyre

Crapo²,

Viegi³

et al. 2005

Eur Respir J

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1,469

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“…[192] This air pocket represents 8-9% of its body volume, which happens to be very similar to the proportion of lung capacity to body volume in humans. [192,193] Unlike vertebrates, however, insects employing plastron-based respiration rely entirely on passive diffusion of oxygen through water into their breathing bubbles. These insects are therefore constrained in body size: metabolic rates in insects increase more steeply than surface area with increasing mass.…”

Section: Systems For Sub-aquatic Exchangementioning

confidence: 99%

It's Not a Bug, It's a Feature: Functional Materials in Insects

2018

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Over the course of their wildly successful proliferation across the earth, the insects as a taxon have evolved enviable adaptations to their diverse habitats, which include adhesives, locomotor systems, hydrophobic surfaces, and sensors and actuators that transduce mechanical, acoustic, optical, thermal, and chemical signals. Insect‐inspired designs currently appear in a range of contexts, including antireflective coatings, optical displays, and computing algorithms. However, as over one million distinct and highly specialized species of insects have colonized nearly all habitable regions on the planet, they still provide a largely untapped pool of unique problem‐solving strategies. With the intent of providing materials scientists and engineers with a muse for the next generation of bioinspired materials, here, a selection of some of the most spectacular adaptations that insects have evolved is assembled and organized by function. The insects presented display dazzling optical properties as a result of natural photonic crystals, precise hierarchical patterns that span length scales from nanometers to millimeters, and formidable defense mechanisms that deploy an arsenal of chemical weaponry. Successful mimicry of these adaptations may facilitate technological solutions to as wide a range of problems as they solve in the insects that originated them.

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The effect of age, body size and lung volume change on alveolar‐capillary permeability and diffusing capacity in man

Cited by 168 publications

References 14 publications

In defence of the carbon monoxide transfer coefficientK_CO(T_L/V_A)

In defence of the carbon monoxide transfer coefficientK_CO(T_L/V_A)

Standardisation of the single-breath determination of carbon monoxide uptake in the lung

It's Not a Bug, It's a Feature: Functional Materials in Insects

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The effect of age, body size and lung volume change on alveolar‐capillary permeability and diffusing capacity in man

Cited by 168 publications

References 14 publications

In defence of the carbon monoxide transfer coefficientKCO(TL/VA)

In defence of the carbon monoxide transfer coefficientKCO(TL/VA)

Standardisation of the single-breath determination of carbon monoxide uptake in the lung

It's Not a Bug, It's a Feature: Functional Materials in Insects

Contact Info

Product

Resources

About

In defence of the carbon monoxide transfer coefficientK_CO(T_L/V_A)

In defence of the carbon monoxide transfer coefficientK_CO(T_L/V_A)