Effects of homogeneous and heterogeneous changes in the lung periphery on spirometry results

2019 ◽  
Vol 173 ◽  
pp. 139-145 ◽  
Author(s):  
Adam G. Polak ◽  
Dariusz Wysoczański ◽  
Janusz Mroczka
Keyword(s):  
Lung Periphery

Perfusion of lung periphery: effects of local exposures to ozone and pressure

1986 ◽  
Vol 61 (2) ◽  
pp. 640-646
Author(s):  
A. N. Freed ◽  
U. A. Scheffel ◽  
L. J. Kelly ◽  
B. Bromberger-Barnea ◽  
H. A. Menkes
Keyword(s):  
High Pressure ◽  
Pulmonary Perfusion ◽  
Alveolar Pressure ◽  
Anesthetized Dogs ◽  
Lung Periphery ◽  
Airways Reactivity ◽  
Collateral System

Following ozone (O3) exposure, airways reactivity increases. We investigated the possibility that exposure to O3 causes a decrease in pulmonary perfusion, and that this decrease is associated with the increase in reactivity. Perfusion was measured with radiolabeled microspheres. A wedged bronchoscope was used to isolate sublobar segments in the middle and lower lobes of anesthetized dogs. Isolated segments were exposed to either O3 or an elevated alveolar pressure. Although increased alveolar pressure decreased microsphere density, exposure to 1 ppm O3 did not. Collateral system resistance rose significantly following exposure to O3 and to high pressure. These studies do not support the hypothesis that pulmonary perfusion is decreased following O3 exposure and is associated with subsequent increases in reactivity.

Airway pressures in an asymmetrically branched airway model of the dog respiratory system

1984 ◽  
Vol 57 (4) ◽  
pp. 1222-1230 ◽  
Author(s):  
Andrew C. Jackson ◽  
Mehrdad Tabrizi ◽  
Michael I. Kotlikoff ◽  
Jon R. Voss
Keyword(s):  
Respiratory System ◽  
High Frequency ◽  
High Frequency Ventilation ◽  
Tissue Properties ◽  
Pressure Distributions ◽  
Lumped Parameter ◽  
Airway Opening ◽  
Frequency Ventilation ◽  
Lung Periphery ◽  
Airway Model

A computer model of the mechanical properties of the dog respiratory system based on the asymmetrically branching airway model of Horsfield et al. (11) is described. The peripheral ends of this airway model were terminated by a lumped-parameter impedance representing gas compression in the alveoli, and lung and chest wall tissue properties were derived from measurements made in this laboratory. Using this model we predicted the respiratory system impedance and the distribution of pressures along the airways in the dog lung. Predicted total respiratory system impedances for frequencies between 4 and 64 Hz at three lung volumes were found to compare quite closely to measured impedances in dogs. Serial pressure distributions were found to be frequency-dependent and to result in higher pressures in the lung periphery than at the airway opening at some frequencies. The implications of this fading for high-frequency ventilation are discussed. impedance; high-frequency ventilation; central airway resistance; respiratory system resistance; airway pressure distribution; distribution of ventilation Submitted on November 14, 1983 Accepted on May 8, 1984

Unusual thoracic radiographic findings in children treated for Hodgkin's disease.

1986 ◽  
Vol 4 (6) ◽  
pp. 874-882 ◽  
Author(s):  
M S Jochelson ◽  
N J Tarbell ◽  
H J Weinstein
Keyword(s):  
Hodgkin's Disease ◽  
Radiation Pneumonitis ◽  
Hodgkin’S Disease ◽  
Combined Modality Therapy ◽  
Radiographic Findings ◽  
Appropriate Treatment ◽  
Mediastinal Widening ◽  
Lung Periphery ◽  
Inflammatory Changes ◽  
Radiographic Changes

Mantle irradiation is often part of the treatment for Hodgkin's disease. Localized pneumonitis and fibrosis are well-known sequelae of this treatment. We report nine patients with unusual thoracic radiographic findings following treatment for Hodgkin's disease. All nine had mediastinal widening. Seven of these patients received combined modality therapy in which prednisone was given with their MOPP. In these seven patients, an increase in mediastinal width developed at the same time as the radiographic changes of radiation pneumonitis. Two patients developed bilateral infiltrates extending beyond the field of radiation to the lung periphery. In one of these patients, a spontaneous pneumomediastinum developed. One patient underwent mediastinal biopsy that revealed inflammatory changes similar to those seen in radiation pneumonitis. All patients either responded to steroids or had spontaneous regression of radiographic abnormalities supporting the presumed diagnosis of treatment related changes. Recognition of these unusual sequelae of mantle irradiation will aid in differentiating them from infection or tumor and lead to prompt, appropriate treatment.

How changes in the serial distribution of bronchoconstriction affect lung mechanics

1993 ◽  
Vol 74 (6) ◽  
pp. 2838-2847 ◽  
Author(s):  
F. M. Robatto ◽  
S. Simard ◽  
M. S. Ludwig
Keyword(s):  
Direct Effect ◽  
Coefficient Of Variation ◽  
Lung Parenchyma ◽  
Lung Mechanics ◽  
Response Curves ◽  
Mechanical Heterogeneity ◽  
Airway Constriction ◽  
Lung Resistance ◽  
Lung Periphery ◽  
Central Airway

It is generally accepted that methacholine (MCh) acts predominantly on the central airways and histamine (H) acts on the lung periphery. We hypothesized therefore that lung mechanics would be affected differently by H and MCh aerosols. In 12 anesthetized paralyzed open-chest mongrel dogs, we obtained MCh (0.1–30 mg/ml, n = 6) and H (0.1–30 mg/ml, n = 6) concentration-response curves. The alveolar capsule technique was used to partition lung resistance (RL) into airway (Raw) and tissue (Rti) components. The degree of mechanical heterogeneity across the lung was assessed by computing the coefficient of variation for five alveolar pressures during relaxed expirations. RL increased 823 +/- 202% after H and 992 +/- 219% after MCh. Rti increased 784 +/- 192% after H and 1,014 +/- 279% after MCh. Raw increased 1,098 +/- 297% after H and 1,275 +/- 332% after MCh. Elastance increased 342 +/- 53% after H and 423 +/- 88% after MCh. The coefficient of variation increased 279 +/- 65% after H and 252 +/- 55% after MCh. The patterns of change were similar throughout the H and MCh concentration-response curves. We conclude that H and MCh have comparable effects on lung mechanics and that the degree and pattern of heterogeneity inside the lung after constriction are the same regardless of the agent used. These data support the hypothesis that H and MCh have some similar direct effect on the lung parenchyma. Parenchymal deformation after MCh-induced central airway constriction alone would be unlikely to explain increases in Rti of this magnitude or changes in lung mechanics so similar to those induced by H.

Diffusivity dependence of multiple-breath washouts of lung periphery

1990 ◽  
Vol 68 (1) ◽  
pp. 76-83 ◽  
Author(s):  
G. G. Berdine ◽  
D. Dale ◽  
J. E. Johnson ◽  
J. L. Lehr
Keyword(s):  
Tidal Volume ◽  
Exponential Decay ◽  
Local Minimum ◽  
Local Maximum ◽  
Inspiratory Flow ◽  
Normal Range ◽  
Lung Periphery ◽  
Kinetics Of ◽  
And Diffusion ◽  
Single Exponential

Subpleural concentrations of He and SF6 were measured during multiple-breath washouts from isolated dog lungs. Tidal volume, inspiratory flow, and frequency were in the normal range of canine ventilation. For each gas, there was a local minimum in concentration during inspiration (Cinsp) and a local maximum in concentration during exhalation (Cexp). SF6 exhibited a deeper inspiratory trough than He for each breath of every washout. For large tidal volumes (10-20 ml/kg), Cexp approximated a single exponential decay and He was cleared more rapidly than SF6. For small tidal volumes (2.5 ml/kg), Cexp was multiexponential and SF6 was cleared more rapidly than He. Cinsp/Cexp (a measure of the depth of the inspiratory trough) and the kinetics of Cexp decay were determined for washouts using a tidal volume of 10 and 20 ml/kg and different inspiratory flows. Under all conditions, an increase of inspiratory flow resulted in a deeper inspiratory trough for both He and SF6. For washouts using 10 ml/kg and 60 breaths/min, an increase of inspiratory flow increased the clearance of both gases. In washouts using lower ventilatory frequencies, gas clearance was independent of inspiratory flow. These findings are contrary to predictions of contemporary models of convection and diffusion in the lung. This study suggests that convective axial mixing and radial diffusion in the airways are important determinants of pulmonary gas transport.

Respiratory impedance and multibreath N2 washout in healthy, asthmatic, and cystic fibrosis subjects

1990 ◽  
Vol 68 (5) ◽  
pp. 2139-2149 ◽  
Author(s):  
K. R. Lutchen ◽  
R. H. Habib ◽  
H. L. Dorkin ◽  
M. A. Wall
Keyword(s):  
Cystic Fibrosis ◽  
Normal Subjects ◽  
Forced Expiratory Volume ◽  
The Other ◽  
Poor Correlation ◽  
Base Line ◽  
Respiratory Impedance ◽  
Ventilation Distribution ◽  
Peripheral Airway ◽  
Lung Periphery

We measured forced expiratory volume in 1 s (FEV1), respiratory impedance (Zrs) from 4 to 60 Hz, and a multibreath N2 washout (MBNW) in 6 normal, 10 asthmatic, and 5 cystic fibrosis (CF) subjects. The MBNW were characterized by the mean dilution number (MDN) derived by a moment analysis. The Zrs spectra were characterized by the minimum resistance (Rmin), the drop in resistance (Rdrop) from 4 Hz to Rmin, and the first resonance frequency (Fr1). Measurements were repeated after bronchodilation in three normal and all asthmatic subjects. Before bronchodilation, six of the asthmatic subjects showed close to normal FEV1. The Zrs in the normal subjects showed low Rmin (1.9 +/- 0.7 cmH2O.l-1.s), Rdrop (0.4 +/- 0.4), and Fr1 (10 +/- 2 Hz). Four of the mildly obstructed asthmatic subjects had normal Zrs but elevated MDNs (i.e., abnormal ventilation distribution). The other six asthmatic subjects had significantly elevated Rmin (4.1 +/- 0.8), Rdrop (6.3 +/- 5.8), and Fr1 (34 +/- 0.4 Hz) and elevated MDNs. The CF patients had elevated Zrs features and MDNs. After bronchodilation, no changes in FEV1, MDN, or Zrs occurred in the normal subjects. All asthmatic subjects showed increased FEV1 and decreased MDN, but the Zrs was unaltered in the four asthmatic subjects whose base-line Zrs was normal. For the other six asthmatic subjects, there were large decreases in the Rmin, Rdrop, and Fr1. Finally, there was a poor correlation between the MDN and the Zrs features but high correlation between the Zrs features alone. These results imply that significant nonuniform peripheral airway obstruction can exist such that ventilation distribution is abnormal but Zrs from 4 to 60 Hz is not. Abnormalities in Zrs from 4 to 60 Hz occur only after significant overall obstruction in the peripheral and more central airways. Combining Zrs and the MBNW may permit us to infer whether the disease is predominantly in the lung periphery or in the more central airways.

Vagal control of central and peripheral pulmonary resistance in developing piglets

1991 ◽  
Vol 70 (4) ◽  
pp. 1617-1626 ◽  
Author(s):  
J. J. Perez Fontan ◽  
A. O. Ray
Keyword(s):  
Vagal Stimulation ◽  
Muscle Tone ◽  
Positive Pressure ◽  
Large Contribution ◽  
Postnatal Maturation ◽  
Peripheral Airways ◽  
Vagal Control ◽  
Vagal Innervation ◽  
Lung Periphery ◽  
Alpha Chloralose

To study the postnatal maturation of vagal control of airway muscle tone, we determined the effects of vagotomy and supramaximal vagal stimulation on the resistance of the respiratory system in eight newborn and seven 6-wk-old piglets. Because the lung periphery has distinctive responses to cholinergic agonists and a lower density of vagal fibers and cholinergic receptors than the central airways, we partitioned the respiratory resistance of the piglets between central airways (Rc) and peripheral airways and lung tissue (Rp) with bronchial catheters inserted in a retrograde manner. The piglets were anesthetized with alpha-chloralose and ventilated with positive airway pressure. Vagotomy did not change Rc or Rp in either the newborn or the 6-wk-old piglets. Vagal stimulation, on the other hand, increased both Rc (median increase 53% in the newborn and 72% in the 6-wk-old piglets) and Rp (54 and 42%, respectively). At all states of vagal tone, Rp increased as the lungs were inflated, suggesting a large contribution of tissue viscoelasticity to this resistance. Our results demonstrate that vagal bronchomotor tone is absent during mechanical ventilation with positive pressure in the developing piglet. However, vagal innervation of both central airways and tissue contractile elements is functionally competent at the time of birth in this species.

A human acinar structure for simulation of realistic alveolar plateau slopes

2000 ◽  
Vol 89 (5) ◽  
pp. 1859-1867 ◽  
Author(s):  
Brigitte Dutrieue ◽  
Frederique Vanholsbeeck ◽  
Sylvia Verbanck ◽  
Manuel Paiva
Keyword(s):  
Normal Subjects ◽  
Sensitivity Study ◽  
Phase Iii ◽  
Normal Lung ◽  
Acinar Structure ◽  
Lung Structure ◽  
Solving Equations ◽  
Different Depths ◽  
Lung Periphery ◽  
Successive Generations

We simulated the intra-acinar contribution to phase III slope ( S acin) for gases of differing diffusivities (He and SF6) by solving equations of diffusive and convective gas transport in multi-branch-point models (MBPM) of the human acinus. We first conducted a sensitivity study of S acin to asymmetry and its variability in successive generations. S acin increases were greatest when asymmetry and variability of asymmetry were increased at the level of the respiratory bronchioles (generations 17–18) for He and at the level of the alveolar ducts (generations 20–21) for SF6, corresponding to the location of their respective diffusion fronts. On the basis of this sensitivity study and in keeping with reported acinar morphometry, we built a MBPM that actually reproduced experimental S acin values obtained in normal subjects for He, N2, and SF6. Ten variants of such a MBPM were constructed to estimate intrinsic S acin variability owing to peripheral lung structure. The realistic simulation of S acin in the normal lung and the understanding of how asymmetry affects S acin for different diffusivity gases make S acin a powerful tool to detect structural alterations at different depths in the lung periphery.

Effect of methacholine on peripheral lung mechanics and ventilation heterogeneity in asthma

2013 ◽  
Vol 114 (6) ◽  
pp. 770-777 ◽  
Author(s):  
Sue R. Downie ◽  
Cheryl M. Salome ◽  
Sylvia Verbanck ◽  
Bruce R. Thompson ◽  
Norbert Berend ◽  
...  
Keyword(s):  
Frequency Dependence ◽  
Forced Vital Capacity ◽  
Vital Capacity ◽  
Lung Mechanics ◽  
Forced Oscillation Technique ◽  
Airway Closure ◽  
Asthmatic Patients ◽  
Ventilation Heterogeneity ◽  
Trapped Gas ◽  
Lung Periphery

The forced oscillation technique (FOT) and multiple-breath nitrogen washout (MBNW) are noninvasive tests that are potentially sensitive to peripheral airways, with MBNW indexes being especially sensitive to heterogeneous changes in ventilation. The objective was to study methacholine-induced changes in the lung periphery of asthmatic patients and determine how changes in FOT variables of respiratory system reactance (Xrs) and resistance (Rrs) and frequency dependence of resistance (Rrs5-Rrs19) can be linked to changes in ventilation heterogeneity. The contributions of air trapping and airway closure, as extreme forms of heterogeneity, were also investigated. Xrs5, Rrs5, Rrs19, Rrs5-Rrs19, and inspiratory capacity (IC) were calculated from the FOT. Ventilation heterogeneity in acinar and conducting airways, and trapped gas (percent volume of trapped gas at functional residual capacity/vital capacity), were calculated from the MBNW. Measurements were repeated following methacholine. Methacholine-induced airway closure (percent change in forced vital capacity) and hyperinflation (change in IC) were also recorded. In 40 mild to moderate asthmatic patients, increase in Xrs5 after methacholine was predicted by increases in ventilation heterogeneity in acinar airways and forced vital capacity ( r2 = 0.37, P < 0.001), but had no correlation with ventilation heterogeneity in conducting airway increase or IC decrease. Increases in Rrs5 and Rrs5-Rrs19 after methacholine were not correlated with increases in ventilation heterogeneity, trapped gas, hyperinflation, or airway closure. Increased reactance in asthmatic patients after methacholine was indicative of heterogeneous changes in the lung periphery and airway closure. By contrast, increases in resistance and frequency dependence of resistance were not related to ventilation heterogeneity or airway closure and were more indicative of changes in central airway caliber than of heterogeneity.

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