Relationship of end-expiratory pressure, lung volume, and 99mTc-DTPA clearance

1987 ◽  
Vol 63 (4) ◽  
pp. 1586-1590 ◽  
Author(s):  
J. A. Cooper ◽  
H. van der Zee ◽  
B. R. Line ◽  
A. B. Malik
Keyword(s):  
Lung Volume ◽  
Clearance Rate ◽  
Base Line ◽  
Lung Inflation ◽  
Alveolar Epithelial ◽  
Pulmonary Clearance ◽  
Residual Capacity ◽  
Dose Response Effect ◽  
Relationship Of ◽  
Line P

We investigated the dose-response effect of positive end-expiratory pressure (PEEP) and increased lung volume on the pulmonary clearance rate of aerosolized technetium-99m-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA). Clearance of lung radioactivity was expressed as percent decrease per minute. Base-line clearance was measured while anesthetized sheep (n = 20) were ventilated with 0 cmH2O end-expiratory pressure. Clearance was remeasured during ventilation at 2.5, 5, 10, 15, or 20 cmH2O PEEP. Further studies showed stepwise increases in functional residual capacity (FRC) (P less than 0.05) measured at 0, 2.5, 5, 10, 15, and 20 cmH2O PEEP. At 2.5 cmH2O PEEP, the clearance rate was not different from that at base line (P less than 0.05), although FRC was increased from base line. Clearance rate increased progressively with increasing PEEP at 5, 10, and 15 cmH2O (P less than 0.05). Between 15 and 20 cmH2O PEEP, clearance rate was again unchanged, despite an increase in FRC. The pulmonary clearance of aerosolized 99mTc-DTPA shows a sigmoidal response to increasing FRC and PEEP, having both threshold and maximal effects. This relationship is most consistent with the hypothesis that alveolar epithelial permeability is increased by lung inflation.

scholarly journals Assessment of the influence of lung inflation state on the quantitative parameters derived from hyperpolarized gas lung ventilation MRI in healthy volunteers

2019 ◽  
Vol 126 (1) ◽  
pp. 183-192 ◽  
Author(s):  
Paul J. C. Hughes ◽  
Laurie Smith ◽  
Ho-Fung Chan ◽  
Bilal A. Tahir ◽  
Graham Norquay ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Lung Volume ◽  
Lung Ventilation ◽  
Lung Volumes ◽  
Lung Inflation ◽  
Longitudinal Measurements ◽  
Anatomical Images ◽  
Lower Lung ◽  
Ventilation Heterogeneity ◽  
Residual Capacity

In this study, the effect of lung volume on quantitative measures of lung ventilation was investigated using MRI with hyperpolarized 3He and 129Xe. Six volunteers were imaged with hyperpolarized 3He at five different lung volumes [residual volume (RV), RV + 1 liter (1L), functional residual capacity (FRC), FRC + 1L, and total lung capacity (TLC)], and three were also imaged with hyperpolarized 129Xe. Imaging at each of the lung volumes was repeated twice on the same day with corresponding 1H lung anatomical images. Percent lung ventilated volume (%VV) and variation of signal intensity [heterogeneity score (Hscore)] were evaluated. Increased ventilation heterogeneity, quantified by reduced %VV and increased Hscore, was observed at lower lung volumes with the least ventilation heterogeneity observed at TLC. For 3He MRI data, the coefficient of variation of %VV was <1.5% and <5.5% for Hscore at all lung volumes, while for 129Xe data the values were 4 and 10%, respectively. Generally, %VV generated from 129Xe images was lower than that seen from 3He images. The good repeatability of 3He %VV found here supports prior publications showing that percent lung-ventilated volume is a robust method for assessing global lung ventilation. The greater ventilation heterogeneity observed at lower lung volumes indicates that there may be partial airway closure in healthy lungs and that lung volume should be carefully considered for reliable longitudinal measurements of %VV and Hscore. The results suggest that imaging patients at different lung volumes may help to elucidate obstructive disease pathophysiology and progression. NEW & NOTEWORTHY We present repeatability data of quantitative metrics of lung function derived from hyperpolarized helium-3, xenon-129, and proton anatomical images acquired at five lung volumes in volunteers. Increased regional ventilation heterogeneity at lower lung inflation levels was observed in the lungs of healthy volunteers.

Interstitial fibrosis and collateral ventilation

1986 ◽  
Vol 61 (1) ◽  
pp. 300-303 ◽  
Author(s):  
D. M. Berzon ◽  
H. Menkes ◽  
A. M. Dannenberg ◽  
A. Gertner ◽  
P. Terry ◽  
...  
Keyword(s):  
Lung Volume ◽  
Interstitial Fibrosis ◽  
Local Treatment ◽  
Transpulmonary Pressure ◽  
Small Region ◽  
Similar Proportion ◽  
Collateral Flow ◽  
Lung Inflation ◽  
Fibrotic Process ◽  
Residual Capacity

Interstitial fibrosis may increase resistance to collateral flow (Rcoll) because of decreased lung volume and destruction of collateral channels or it may decrease Rcoll because of emphysematous changes around fibrotic regions. In addition, if interstitial fibrosis involves a small region of lung periphery, interdependence from surrounding unaffected lung should produce relatively large changes in volume of the fibrotic region during lung inflation. We studied the effects of interstitial fibrosis on collateral airflow by measuring Rcoll at functional residual capacity (FRC) in nine mongrel dogs before and 28 days after the local instillation of bleomycin into selected lung segments. In six of these dogs Rcoll was also measured at a higher lung volume (transpulmonary pressure = 12 cmH2O above FRC pressure). Rcoll increased in fibrotic lung segments following local treatment with bleomycin. With lung inflation (high transpulmonary pressure) Rcoll fell a similar proportion in fibrotic and nonfibrotic lung regions. These observations suggest that collateral resistance increases in fibrotic segments because lung volume decreases or because collateral pathways are involved directly in the fibrotic process. Compensatory increases in collateral communications do not occur. In addition, pulmonary interdependence does not cause disproportionate increases in volume and decreases in Rcoll of the fibrotic region during lung inflation.

Diaphragmatic function during immersion

1977 ◽  
Vol 43 (2) ◽  
pp. 297-301 ◽  
Author(s):  
V. D. Minh ◽  
G. F. Dolan ◽  
P. G. Linaweaver ◽  
P. J. Friedman ◽  
R. G. Konopka ◽  
...  
Keyword(s):  
Respiratory System ◽  
Functional Residual Capacity ◽  
Lung Volume ◽  
Intrathoracic Pressure ◽  
Fold Increase ◽  
Hydrostatic Compression ◽  
Base Line ◽  
Factors Affecting ◽  
Diaphragmatic Function ◽  
Residual Capacity

Diaphragmatic function during immersion to midneck level was studied in upright mongrel dogs, using constant electrophrenic stimulation. Effectiveness of diaphragmatic contraction was analyzed in terms of inspired volume (VT) (with airways open), and change in intrathoracic pressure (Pmus) (with the respiratory system occluded). Hydrostatic compression of the immersed body decreased functional residual capacity (FRC) to 55% base-line value (FRCO), resulting in a 2.8-fold increase in Pmus. In spite of this Pmus increase, VT often decreased during immersion, averaging only 83% VTO (base-line value in air). Hence, immersion was associated with a marked stiffening of the respiratory system. The Pmus increase during immersion persisted after restoration of FRC to FRCO, and was related to diaphragmatic length being greater in water than in air under condition of iso-lung volume. In all, there were three factors affecting diaphragmatic function during immersion: FRC reduction, change in thoracic configuration, and stiffening of the respiratory system.

Effects of lung volume on maximal methacholine-induced bronchoconstriction in normal humans

1987 ◽  
Vol 62 (3) ◽  
pp. 1324-1330 ◽  
Author(s):  
D. J. Ding ◽  
J. G. Martin ◽  
P. T. Macklem
Keyword(s):  
Dose Response ◽  
Lung Volume ◽  
Normal Subjects ◽  
Smooth Muscle Contraction ◽  
Base Line ◽  
Pulmonary Resistance ◽  
Response Curves ◽  
Maximum Value ◽  
Residual Capacity ◽  
Normal Humans

We examined the effects of lung volume on the bronchoconstriction induced by inhaled aerosolized methacholine (MCh) in seven normal subjects. We constructed dose-response curves to MCh, using measurements of inspiratory pulmonary resistance (RL) during tidal breathing at functional residual capacity (FRC) and after a change in end-expiratory lung volume (EEV) to either FRC -0.5 liter (n = 5) or FRC +0.5 liter (n = 2). Aerosols of MCh were generated using a nebulizer with an output of 0.12 ml/min and administered for 2 min in progressively doubling concentrations from 1 to 256 mg/ml. After MCh, RL rose from a base-line value of 2.1 +/- 0.3 cmH2O. 1–1 X s (mean +/- SE; n = 7) to a maximum of 13.9 +/- 1.8. In five of the seven subjects a plateau response to MCh was obtained at FRC. There was no correlation between the concentration of MCh required to double RL and the maximum value of RL. The dose-response relationship to MCh was markedly altered by changing lung volume. The bronchoconstrictor response was enhanced at FRC - 0.5 liter; RL reached a maximum of 39.0 +/- 4.0 cmH2O X 1–1 X s. Conversely, at FRC + 0.5 liter the maximum value of RL was reduced in both subjects from 8.2 and 16.6 to 6.0 and 7.7 cmH2O X 1–1 X s, respectively. We conclude that lung volume is a major determinant of the bronchoconstrictor response to MCh in normal subjects. We suggest that changes in lung volume act to alter the forces of interdependence between airways and parenchyma that oppose airway smooth muscle contraction.

Effects of sustained exercise on pulmonary clearance of aerosolized 99mTc-DTPA

1989 ◽  
Vol 67 (5) ◽  
pp. 2055-2059 ◽  
Author(s):  
A. M. Lorino ◽  
M. Meignan ◽  
P. Bouissou ◽  
G. Atlan
Keyword(s):  
Tidal Volume ◽  
Clearance Rate ◽  
Constant Load ◽  
Pulmonary Mechanics ◽  
Epithelial Permeability ◽  
Alveolar Epithelial ◽  
Pulmonary Clearance ◽  
Before And After ◽  
Pulmonary Volumes ◽  
Constant Load Exercise

The effects of intensive prolonged exercise on the pulmonary clearance rate of aerosolized 99mTc-labeled diethylenetriaminepentaacetate (99mTc-DTPA) and pulmonary mechanics were studied in seven healthy nonsmoking volunteers. 99mTc-DTPA clearance and pulmonary mechanics (lung volumes and compliance) were assessed before and after 75 min of constant-load exercise performed on a treadmill, corresponding to 75% of maximal O2 uptake. Because both clearance measurements were made in similar conditions of pulmonary blood flow, respiratory rate, and tidal volume, changes in clearance rate can be assumed to represent changes of alveolar epithelial permeability. After exercise, total, apical, and basal clearance were significantly increased (P less than 0.01, 0.05, and 0.05, respectively) and the increases in total clearance and tidal volume observed during exercise were significantly correlated (P less than 0.05). In contrast, no significant change was found in pulmonary mechanics. These results show that prolonged intensive exercise induces an increase in epithelial permeability, which appears to be related to the mechanical effects of sustained increased ventilation. Because no change was evidenced in pulmonary volumes or in lung elasticity, our results suggest that this increase may result from alteration of the intercellular tight junctions rather than from a surfactant deficiency.

Effects of hypercapnia on Breuer-Hering threshold for inspiratory termination

1984 ◽  
Vol 57 (4) ◽  
pp. 1211-1221 ◽  
Author(s):  
T. L. Clanton ◽  
W. T. Lipscomb
Keyword(s):  
Tidal Volume ◽  
Lung Volume ◽  
Neural Mechanism ◽  
Co2 Concentration ◽  
Lung Volumes ◽  
Lung Inflation ◽  
Fractional Concentration ◽  
Residual Capacity ◽  
Upward Direction ◽  
Breath Cycle

The effects of CO2 concentration on the timing of inspiratory duration (TI) and expiratory duration (TE) and the responses to lung inflation were studied in decerebrate paralyzed cats. With lung volume held at functional residual capacity during the breath cycle, hypercapnia (fractional concentration of inspired CO2 = 0.04) caused variable changes in TI and significant increases in TE. To obtain the Breuer-Hering threshold relationship [tidal volume (VT) vs. TI] and the timing relationship between TE and the preceding TI (TE vs. TI), ramp inflations of various sizes were used to terminate inspiration at different times in the breath cycle. Hypercapnia caused the VT vs. TI curves to shift in an upward direction so that at higher lung volumes TI was lengthened. Also, the slope of the TE vs. TI relationship was increased. The results suggest that hypercapnia diminished the sensitivity of the Breuer-Hering reflex to the lung volume, thus allowing volume to increase with little effect on TI. In addition, TE appears to become more sensitive to changes in the preceding TI. A model is presented which provides a possible neural mechanism for these responses.

Effects of lung volume on clearance of solutes from the air spaces of lungs

1988 ◽  
Vol 64 (3) ◽  
pp. 1068-1075 ◽  
Author(s):  
B. T. Peterson ◽  
H. L. James ◽  
J. W. McLarty
Keyword(s):  
Human Serum Albumin ◽  
Lung Volume ◽  
Clearance Rate ◽  
Compartmental Analysis ◽  
Compartment Model ◽  
Lung Inflation ◽  
Experimental Animals ◽  
Two Compartment Model ◽  
Additional Control ◽  
Albumin Clearance

Several investigators have shown that the clearance rate of aerosolized 99mTc-labeled diethylenetriamine pentaacetate (DTPA, mol wt = 492, radius = 0.6 nm) from the air spaces of the lungs of humans and experimental animals increases with lung volume. To further investigate this phenomenon we performed a compartmental analysis of the 2-h clearance of DTPA from the lungs of anesthetized sheep using a new method to more accurately correct for the effects of DTPA recirculation. This analysis showed that the DTPA clearance in eight sheep ventilated with zero end-expired pressure was best described by a one-compartment model with a clearance rate of 0.42 ± 0.15%/min. Ventilating eight sheep with an end-expired pressure of 10 cmH2O throughout the study increased the end-expired volume 0.4 ± 0.1 liter BTPS and created a clearance curve that was best described by a two-compartment model. In these sheep 56 ± 16% of the DTPA cleared from the lungs at a rate of 7.9 ± 2.9%/min. The remainder cleared at a rate similar to that measured in the sheep ventilated with zero end-expired pressure (0.35 ± 0.18%/min). Additional control and lung inflation experiments were performed using 99mTc-labeled human serum albumin (mol wt = 66,000, radius = 3.6 nm). In six control sheep ventilated with zero end-expired pressure the albumin clearance was best described by a one-compartment model with a clearance rate of 0.06 ± 0.02%/min. The clearance rate in six sheep with increased lung volume was slightly larger (0.09 ± 0.02, P less than 0.05) but was well described by a one-compartment model.(ABSTRACT TRUNCATED AT 250 WORDS)

Transpulmonary speed of sound input into the supraclavicular space

2003 ◽  
Vol 94 (2) ◽  
pp. 604-611 ◽  
Author(s):  
R. Paciej ◽  
A. Vyshedskiy ◽  
J. Shane ◽  
R. Murphy
Keyword(s):  
Lung Volume ◽  
Speed Of Sound ◽  
Sound Speed ◽  
Lung Sound ◽  
Lung Capacity ◽  
Transit Times ◽  
Similar Information ◽  
Residual Capacity ◽  
Relationship Of ◽  
The Relationship

The transpulmonary speed of sound input at the mouth has been shown to vary with lung volume. To avoid the disadvantages that exist in certain clinical situations in inputting sound at the mouth, we input sound in the supraclavicular space of 21 healthy volunteers to determine whether similar information on the relationship of sound speed to lung volume could be obtained. We measured the transit time at multiple microphones placed over the chest wall using a 16-channel lung sound analyzer (Stethographics). There was a tight distribution of transit times in this population of subjects. At functional residual capacity, it was 9 ± 1 (SD) ms at the apical sites and 13 ± 1 ms at the lung bases. The sound speed at total lung capacity was 24 ± 2 m/s and was 22 ± 2 m/s at residual volume ( P < 0.001). In all subjects, the speed of sound was faster at higher lung volume. This improved method of studying the mechanism of sound transmission in the lung may help in the development of noninvasive tools for diagnosis and monitoring of lung diseases.

Functional residual capacity and body position in the dog

1978 ◽  
Vol 44 (2) ◽  
pp. 291-296 ◽  
Author(s):  
V. D. Minh ◽  
G. F. Dolan ◽  
B. B. Brach ◽  
K. M. Moser
Keyword(s):  
Lung Volume ◽  
Human Subjects ◽  
Body Position ◽  
Large Data ◽  
Positive Pressure ◽  
Poor Correlation ◽  
Lung Volumes ◽  
Residual Capacity ◽  
Relationship Of ◽  
Large Coefficient

Resting lung volumes in the supine position (FRCs) were determined by N2 washout method in 67 dogs under pentobarbital anesthesia and computed in ml/kg body weight (BW). In 21 other dogs, FRCs and the change in FRC from the supine to upright positions (deltaFRC) were determined; these lung volumes were expressed in ml/kg BW and in percentage of TLC40 (lung volume at 40 cmH2O positive-pressure inflation). It was found that a) FRCs averaged 38.6 plus or minus 8.2 and 42 plus or minus 5.9 ml/kg BW in the two groups of dogs; b) deltaFRC averaged 23 plus or minus 4 ml/kg BW resulted in large data dispersion, a large coefficient of variation (CV) and a poor correlation (r) of lung volume to BW; D) on the contrary, marked uniformity of FRCs and FRCu (upright FRC) was obtained by expressing the resting lung volumes in %TLC40, allowing an accurate prediction of FRC from the inspiratory capacity (IC). Relationship of FRCu to TLC was comparable to human data reported in the literature. FRCs (%TLC40) was smaller than values previously reported for awake human subjects, probably due to the FRCs reduction in our dogs by anesthesia.

Methacholine-induced bronchoconstriction in dogs: effects of lung volume and O3 exposure

1988 ◽  
Vol 65 (6) ◽  
pp. 2679-2686 ◽  
Author(s):  
S. T. Kariya ◽  
S. A. Shore ◽  
W. A. Skornik ◽  
K. Anderson ◽  
R. H. Ingram ◽  
...  
Keyword(s):  
Lung Volume ◽  
Maximal Response ◽  
Maximal Effect ◽  
Response Curves ◽  
Lung Volumes ◽  
Before And After ◽  
Residual Capacity ◽  
Induced Changes ◽  
Conducting Airways ◽  
Concentration Response Curve

The maximal effect induced by methacholine (MCh) aerosols on pulmonary resistance (RL), and the effects of altering lung volume and O3 exposure on these induced changes in RL, was studied in five anesthetized and paralyzed dogs. RL was measured at functional residual capacity (FRC), and lung volumes above and below FRC, after exposure to MCh aerosols generated from solutions of 0.1-300 mg MCh/ml. The relative site of response was examined by magnifying parenchymal [RL with large tidal volume (VT) at fast frequency (RLLS)] or airway effects [RL with small VT at fast frequency (RLSF)]. Measurements were performed on dogs before and after 2 h of exposure to 3 ppm O3. MCh concentration-response curves for both RLLS and RLSF were sigmoid shaped. Alterations in mean lung volume did not alter RLLS; however, RLSF was larger below FRC than at higher lung volumes. Although O3 exposure resulted in small leftward shifts of the concentration-response curve for RLLS, the airway dominated index of RL (RLSF) was not altered by O3 exposure, nor was the maximal response using either index of RL. These data suggest O3 exposure does not affect MCh responses in conducting airways; rather, it affects responses of peripheral contractile elements to MCh, without changing their maximal response.

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