Regional distribution of extravascular water and hematocrit in the lung

Baile, E. M.; Paré, Peter D.; Dahlby, R. W.; Hogg, James C.

doi:10.1152/jappl.1979.46.5.937

Cited by 25 publications

(14 citation statements)

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“…Using the slopes and intercepts of the dissolved-phase 129 Xe signals after the initial exponential buildup, it is possible to quantify the model parameters perfusion, mean transit time, relative blood volume, and hematocrit. Other studies have demonstrated a regional variation of the hematocrit within the lung, and it is unclear whether the lung and peripheral hematocrits are equal (30,31). In this study, the lung hematocrit was estimated to 0.43 Ϯ 0.08 in the LPS group and to 0.55 Ϯ 0.06 in the control group, which reasonably agree with reported peripheral values of 0.…”

supporting

confidence: 89%

Section: Xenon Spectroscopymentioning

confidence: 99%

“…During the breathhold period, the RF pulses and data accumulation were repeated 12 times in an averaging loop before continuing with the next ventilator cycle. The ventilator cycle was repeated 12 times (n ϭ 1…12) with increasing values of the delay ⌬(n) (15,20,30, 40, 60, 90, 120, 150, 200, 300, 400, and 500 ms, respectively), resulting in a total experiment duration of 8 min.Before each experiment, the flip angle of the RF pulses was carefully adjusted to 90°by applying a train of four RF pulses with center frequency at the gas resonance. The adjustment was repeated and the amplitude of the RF pulses fine-tuned until no FID signal could be detected after pulses 2-4.…”

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confidence: 99%

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Characterization of diffusing capacity and perfusion of the rat lung in a lipopolysaccaride disease model using hyperpolarized ¹²⁹Xe

Månsson

Wolber

Driehuys³

et al. 2003

Magnetic Resonance in Med

106

156

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The ability to quantify pulmonary diffusing capacity and perfusion using dynamic hyperpolarized 129 Xe NMR spectroscopy is demonstrated. A model of alveolar gas exchange was developed, which, in conjunction with 129 Xe NMR, enables quantification of average alveolar wall thickness, pulmonary perfusion, capillary diffusion length, and mean transit time. The technique was employed to compare a group of naïve rats (n ‫؍‬ 10) with a group of rats with acute inflammatory lung injury (n ‫؍‬ 10), caused by instillation of lipopolysaccaride (LPS). The measured structural and perfusion-related parameters were in agreement with reported values from studies using non-NMR methods. Significant differences between the groups were found in total diffusion length (control 8.5 ؎ 0.5 m, LPS 9.9 ؎ 0.6 m, P < 0.001), in capillary diffusion length (control 2.9 ؎ 0.4 m, LPS 3.9 ؎ 1.0 m, P < 0.05), and in pulmonary hematocrit (control 0.55 ؎ 0.06, LPS 0.43 ؎ 0.08, P < 0.01), whereas no differences were observed in alveolar wall thickness, pulmonary perfusion, and mean transit time. These results demonstrate the ability of the method to distinguish two main aspects of lung function, namely, diffusing capacity and pulmonary perfusion. Key words: hyperpolarized gas NMR; xenon-129; lung function; diffusing capacity; pulmonary perfusion Gas transfer from ambient air to the blood involves different transport mechanisms. Alveolar ventilation is accomplished by convective transport. Gas transfer within the alveolus and from the alveolus into the blood stream occurs by diffusion along concentration gradients. The blood is then transported from the lungs to peripheral tissues by the pulmonary circulation. These transport processes are affected by a number of lung diseases. Convective transport in the airways is impaired in obstructive lung diseases (1). Diffusion impairment occurs in interstitial lung diseases as well as in pulmonary edema (2). The pulmonary vasculature is affected by both primary lung disease and by left heart failure, causing abnormalities in blood flow (3).The most common method of assessment of diffusion in the alveolar-capillary unit is measurement of the diffusing capacity for carbon monoxide, DL CO (4). The diffusing capacity is defined as the total rate of gas passage across the alveolar-capillary membrane per unit of partial pressure difference of the gas. The tracer gas carbon monoxide diffuses across the alveolar-capillary barrier and is tightly bound to hemoglobin in the erythrocytes. In addition to factors determining diffusion, e.g., the available surface area and the diffusion path length, DL CO therefore depends also on the availability of binding sites, i.e., on hemoglobin concentration and on perfusion. DL CO provides information about diffusion properties of the lung as a whole, but no regional information about function is obtained. By measurement at different partial pressures for oxygen, DL CO can be subdivided into the membrane conductance and a term reflecting the availability of binding sites. This is...

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supporting

confidence: 89%

Section: Xenon Spectroscopymentioning

confidence: 99%

mentioning

confidence: 99%

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Characterization of diffusing capacity and perfusion of the rat lung in a lipopolysaccaride disease model using hyperpolarized ¹²⁹Xe

Månsson

Wolber

Driehuys³

et al. 2003

Magnetic Resonance in Med

106

156

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“…The oxygen content ofeach sample can be calculated by measuring the oxygen tension, the percentage ofoxygen saturation, and the amount of hemoglobin in each sample. Extravascular lung water per gram of blood free dry lung (EVLW) was calculated using the measurements of wet weight and dry weight and 51Cr-counts in each sample as previously described (10). The result was expressed in grams of water per gram of blood-free dry tissue.…”

Section: Methodsmentioning

confidence: 99%

Alveolar epithelial damage. A critical difference between high pressure and oleic acid-induced low pressure pulmonary edema.

Montaner¹,

Tsang²,

Evans³

et al. 1986

J. Clin. Invest.

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The present study was designed to compare high pressure pulmonary edema (HPPE) and oleic acid-induced low pressure pulmonary edema (OAPE) in dogs when similar amounts of extra vascular water were present in the lung. The high pressure edema was produced by intravenous fluid overload and by inflating an aortic balloon catheter (n = 6). The low pressure edema was produced by the injecting 0.08 mg/kg oleic acid suspended in 5 ml saline (n = 6). Comparison of the difference between initial control measurements and final measurements in the edematous states showed that the animals with OAPE had a greater fall in percent oxygen saturation and a greater increase in shunt fractions. The light microscopic studies showed that OAPE was associated with greater amounts of alveolar flooding than HPPE where the edema fluid was located to a greater extent in the peribronchial interstitial space. The electron microscopy studies showed that the alveolar flooding in OAPE was associated with epithelial disruption, and tracer studies carried out in rabbits showed that dextran (150,000 mol wt) could pass from blood to airspace and that dextran (40,000 mol wt) could pass from airspace to blood in OAPE. We conclude that epithelial disruption is responsible for the excessive alveolar flooding in OAPE and that this results in a greater impairment in gas exchange.

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“…Clinically, this seems the case, with edema formation most prominent in dependent parts of the lung of patients with high pulmonary vascular pressures. However, recent data for animals on the location of pulmonary extravascular ,water in normal lungs have not corroborated this observation (Naimark et al, 1971;Baile et al, 1979;Flick et al, 1979). These data have been accumulated using whole lung or animal freezing techniques with subsequent analysis of the wet-to-dry weight ratio of lung slices taken perpendicular to the gravity gradient.…”

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Regional edema formation in isolated perfused dog lungs.

Hales¹,

Kanarek²,

Ahluwalia³

et al. 1981

Circulation Research

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SUMMARY Studies using gravimetric analysis of lungs of frozen animals have suggested that the differences in pulmonary microvascular pressure between non-dependent and dependent lung do not influence the formation of regional pulmonary edema. We wondered if the inability to detect variation in regional extravascular lung water (EVLW) was due to the slow freezing process and, therefore, reassessed the distribution of EVLW in vertically suspended isolated perfused dog lungs with a radioisotopic technique that does not require freezing. Total lung water (TLW), blood or intravascular lung water (FVLW), and EVLW were measured in absolute quantities using a positron camera and the positron-emitting isotopes C I5O as a blood label and H 2 15O as a total lung water label. Mean isotopic TLW in 17 lungs that were normal or moderately edematous (wet:dry ratio < 7) was 142 ± 9 (SE) ml compared to the gravimetric estimate of 148 ± 7 ml (r = 0.92) and isotopic EVLW was 64 ± 6 ml compared to the gravimetric estimate of 70 ± 6 ml (r = 0.8). Analysis of the distribution of regional isotopically measured EVLW in the 17 lungs in various states of spontaneous edema formation revealed a small non-dependent to dependent, gravity-related increase in percent regional EVLW compared to percent regional TLW, which did not vary with the degree of edema in the lung. Serial measurements of absolute regional EVLW in four lungs during spontaneously developing edema also failed to show a disproportionate increase in accumulation of EVLW in any lung zone. Thus, despite the wide variation in microvascular hydrostatic pressure between-top and bottom of the vertical isolated lung, edema formation seems to be uniform.

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Regional distribution of extravascular water and hematocrit in the lung

Cited by 25 publications

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Characterization of diffusing capacity and perfusion of the rat lung in a lipopolysaccaride disease model using hyperpolarized ¹²⁹Xe

Characterization of diffusing capacity and perfusion of the rat lung in a lipopolysaccaride disease model using hyperpolarized ¹²⁹Xe

Alveolar epithelial damage. A critical difference between high pressure and oleic acid-induced low pressure pulmonary edema.

Regional edema formation in isolated perfused dog lungs.

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Regional distribution of extravascular water and hematocrit in the lung

Cited by 25 publications

References 0 publications

Characterization of diffusing capacity and perfusion of the rat lung in a lipopolysaccaride disease model using hyperpolarized 129Xe

Characterization of diffusing capacity and perfusion of the rat lung in a lipopolysaccaride disease model using hyperpolarized 129Xe

Alveolar epithelial damage. A critical difference between high pressure and oleic acid-induced low pressure pulmonary edema.

Regional edema formation in isolated perfused dog lungs.

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Characterization of diffusing capacity and perfusion of the rat lung in a lipopolysaccaride disease model using hyperpolarized ¹²⁹Xe

Characterization of diffusing capacity and perfusion of the rat lung in a lipopolysaccaride disease model using hyperpolarized ¹²⁹Xe