Influence of bronchomotor tone on regional ventilation distribution at residual volume

1976 ◽  
Vol 40 (3) ◽  
pp. 411-416 ◽  
Author(s):  
L. A. Engel ◽  
L. Landau ◽  
L. Taussig ◽  
R. R. Martin ◽  
G. Sybrecht
Keyword(s):  
Normal Subjects ◽  
Ventilation Distribution ◽  
Regional Ventilation ◽  
Critical Opening ◽  
Topographical Distribution ◽  
Before And After ◽  
Lower Lung ◽  
The Difference ◽  
Opening And Closing ◽  
Bronchomotor Tone

We studied the topographical distribution of 133Xe boluses inhaled slowly from RV, as well as the distribution of regional volumes at RV (RVr) in seven seated normal subjects before and after aerosolized isoprenaline (ISO) and after aerosolized methacholine hydrochloride (Mech). After Mech the ratio of inhaled 133Xe in the upper lung regions to that in lower lung regions (U/L) decreased from 3.21 +/- .33 (mean +/- 1 SE) to 1.27 +/- 0.12 (P less than 0.001) and returned to 3.89 +/- 0.55 after Iso. Iso alone increased U/L from 3.23 +/- 0.47 to 5.49 +/- 0.85 (P less than 0.025). The height of phase IV in expired 133Xe vs. volume plots correlated with U/L, being greater after Iso and smaller after Mech in each subject. The difference in RVr between upper and lower lung regions decreased after Mech in four out of five subjects from 0.22 TLC to 0.11 TLC. Iso alone did not change the gradient of RVr. The results are consistent with the concept that increased bronchomotor tone widens the range of critical opening and closing pressures with a more patchy and extensive distribution of airway closure.

Effect of bronchomotor tone on static mechanical properties of lung and ventilation distribution

1987 ◽  
Vol 63 (6) ◽  
pp. 2278-2285 ◽  
Author(s):  
A. B. Crawford ◽  
M. Makowska ◽  
L. A. Engel
Keyword(s):  
Mechanical Properties ◽  
Normal Subjects ◽  
Elastic Recoil ◽  
Ventilation Distribution ◽  
Ventilation Inhomogeneity ◽  
Before And After ◽  
Static Mechanical ◽  
Lung Periphery ◽  
Static Mechanical Properties ◽  
Bronchomotor Tone

To study the relationship between bronchomotor tone, static mechanical properties of the lung, and ventilation distribution, we measured the pressure-volume (P-V) curve of the lung and several ventilatory indexes before and after intravenous atropine in eight normal subjects. The indexes of ventilation distribution were derived from multiple breath N2 washouts by a recently developed analysis (7,8). The latter not only provides a sensitive measure of overall ventilation inhomogeneity but distinguishes between the convection-dependent inhomogeneity (CDI) among larger lung units and that due to the interaction of convection and diffusion (DCDI) within the lung periphery. Atropine decreased lung elastic recoil but distensibility, as defined by the exponent (K) in the monoexponential analysis of the P-V data, was unchanged. The overall ventilation inhomogeneity increased by 37% after atropine (P less than 0.02) due to an increase in the CDI component. More importantly, there was a significant correlation between the loss of lung recoil (but not K) and each of the indexes of CDI among the subjects. There was no correlation between the changes in lung recoil and in DCDI. Our findings indicate that normal bronchomotor tone contributes to the elastic recoil of the lung. Furthermore, the tone is distributed in a way that enhances the uniformity of ventilation distribution among diffusion-independent lung units. Presumably this is achieved by minimizing interacinar intrinsic inequalities in static mechanical properties.

Changes in flow-volume curve configuration with bronchoconstriction and bronchodilation

1986 ◽  
Vol 61 (6) ◽  
pp. 2243-2251 ◽  
Author(s):  
C. R. O'Donnell ◽  
R. G. Castile ◽  
J. Mead
Keyword(s):  
Vital Capacity ◽  
Normal Subjects ◽  
Flow Volume ◽  
Slope Ratio ◽  
Lung Volumes ◽  
Volume Curve ◽  
Before And After ◽  
Lower Lung ◽  
Maximum Expiratory Flow ◽  
Flow Volume Curve

Changes in the configuration of maximum expiratory flow-volume (MEFV) curves following mild degrees of bronchodilation or bronchoconstriction were studied in five normal and five asthmatic subjects. In a volume-displacement plethysmograph, MEFV curves were performed before and after inhalation of aerosolized isoproterenol (I) or histamine (H). Five filtered MEFV curves were averaged, and slope ratio vs. volume (SR-V) plots were obtained from averaged curves. Following I, maximal flows at 75% of the vital capacity (VC) were decreased in asthmatics but not in normal subjects. Flows at 50 and 25% of the VC increased in normal subjects and asthmatics, whereas VC′s were unchanged. In asthmatics, sudden large decreases in flow (bumps) occurred at lower lung volumes following I. H reduced flows over the entire VC, with greater reductions occurring in asthmatics than in normals, particularly at low lung volumes. In asthmatics, VC was slightly reduced, and bumps in MEFV curve configuration occurred at higher lung volumes or were abolished entirely following H. A reduction in the amount of configurational detail appreciable in MEFV curves following histamine in asthmatics was best seen in SR-V plots. Following H, SR′s decreased regularly with decreasing lung volume in all the asthmatics but in none of the normals. This was the single most striking finding of this study. Mild I- and H-induced perturbations of airway bronchomotor tone produced small but consistent changes in MEFV curve configuration.(ABSTRACT TRUNCATED AT 250 WORDS)

Similar ventilation distribution in normal subjects prone and supine during tidal breathing

2002 ◽  
Vol 92 (2) ◽  
pp. 622-626 ◽  
Author(s):  
M. J. Rodríguez-Nieto ◽  
G. Peces-Barba ◽  
N. González Mangado ◽  
M. Paiva ◽  
S. Verbanck
Keyword(s):  
Normal Subjects ◽  
Phase Iii ◽  
Ventilation Distribution ◽  
Tidal Breathing ◽  
Ventilation Heterogeneity ◽  
Multiple Breath Washout ◽  
Residual Capacity ◽  
Slope Difference ◽  
The Difference ◽  
Phase Iii Slope

Multiple-breath washout (MBW) tests, with end-expiratory lung volume at functional residual capacity (FRC) and 90% O2, 5% He, and 5% SF6as an inspired gas mixture, were performed in healthy volunteers in supine and prone postures. The semilog plot of MBW N2concentrations was evaluated in terms of its curvilinearity. The MBW N2normalized slope analysis yielded indexes of acinar and conductive ventilation heterogeneity (Verbanck S, Schuermans D, Van Muylem A, Paiva M, Noppen M, and Vincken W. J App Physiol 83: 1907–1916, 1997). Also, the difference between SF6and He normalized phase III slopes was computed in the first MBW expiration. Only MBW tests with similar FRC in the prone and supine postures ( P > 0.1; n= 8) were considered. Prone and supine postures did not reveal any significant differences in curvilinearity, N2normalized slope-derived indexes of conductive or acinar ventilation heterogeneity, nor SF6-He normalized phase III slope difference in the first MBW expiration ( P > 0.1 for all). The absence of significant changes in any of the MBW indexes suggests that ventilation heterogeneity is similar in the supine and prone postures of normal subjects breathing near FRC.

Effect of methacholine on low-frequency mechanics of canine airways and lung tissue

1993 ◽  
Vol 75 (1) ◽  
pp. 55-62 ◽  
Author(s):  
J. Sato ◽  
B. Suki ◽  
B. L. Davey ◽  
J. H. Bates
Keyword(s):  
Continuous Distribution ◽  
Low Frequency ◽  
Constant Term ◽  
Ventilation Distribution ◽  
Regional Ventilation ◽  
Ventilation Inhomogeneity ◽  
Tracheal Pressure ◽  
Before And After ◽  
Volume Oscillation ◽  
Uneven Ventilation

We measured tracheal flow, tracheal pressure, and alveolar capsule pressure in four anesthetized paralyzed tracheostomized open-chest dogs. Lung impedance between 0.12 and 4.88 Hz was measured with a forced volume oscillation technique before and after the intravenous administration of methacholine (MCh). Before MCh administration, lung impedance was well described by a model featuring a single airway leading to an alveolar region surrounded by tissue with a continuous distribution of viscoelastic time constants as used by Hantos et al. (J. Appl. Physiol. 68: 849–860, 1990). After MCh, however, this model gave a poor fit to the impedances. The impedances were well accounted for, however, when the model was enhanced to include an extra time constant term, which we suspect is required to account for the uneven ventilation distribution produced by MCh. Airway impedance before MCh administration was well described by a simple resistance-inertance model, but a model incorporating serial inhomogeneity of ventilation was again required after MCh. Our results support those of previous studies indicating that the impedance of the normal dog lung is well described by a homogeneously ventilated viscoelastic tissue model. In contrast, our results after MCh administration show strong evidence of marked regional ventilation inhomogeneity in addition to the rheological properties of the tissues.

Frequency dependence of ventilation distribution in normal and obstructed lungs

1977 ◽  
Vol 42 (4) ◽  
pp. 548-553 ◽  
Author(s):  
R. L. Jones ◽  
T. R. Overton ◽  
B. J. Sproule
Keyword(s):  
Frequency Dependence ◽  
Regional Distribution ◽  
Normal Subjects ◽  
Relative Distribution ◽  
Breathing Frequency ◽  
Ventilation Distribution ◽  
Regional Ventilation ◽  
Frequency Dependent ◽  
Asthmatic Patients ◽  
Airway Function

Differences in regional pulmonary time constant may cause ventilation distribution to vary with breathing frequency and frequency-dependent changes in regional ventilation per unit volume might be expected. We measured the regional distribution of inhaled xenon-133 (133Xe) at 10 and 60 breaths/min in normal subjects and in patients with a clinical diagnosis of chornic bronchitis or asthma. Breathing frequency had no siqnificant effect on ventilation distribution in normals but in patients with chronic bronchitis ventilation decreased in the lower lung regions at 60 breaths/min compared with 10 breaths/min. In six asthmatic patients the lung regions demonstrating the greatest frequency-dependent reductions in ventilation, which were assumed to have the greatest time constants, also showed decreased ventilation-perfusion ratios (V/Q) measured by standard 133Xe techniques. Bronchodilator increased ventilation more than perfusion in these regions and thus V/Q ratio increased toward the normal range. These results imply that measurement of the frequency dependence of regional ventilation provides information about the relative distribution of airway obstruction, and that airway function in the most obstructed lung regions in asthmatics is improved following bronchodilator therapy.

scholarly journals Ventilation-perfusion distribution in normal subjects

2012 ◽  
Vol 113 (6) ◽  
pp. 872-877 ◽  
Author(s):  
Kenneth C. Beck ◽  
Bruce D. Johnson ◽  
Thomas P. Olson ◽  
Theodore A. Wilson
Keyword(s):  
Regional Distribution ◽  
Normal Subjects ◽  
Bivariate Distribution ◽  
Moderate Exercise ◽  
Ventilation Distribution ◽  
Expired Gas ◽  
The Difference ◽  
Log Normal ◽  
Log Normal Distribution ◽  
Ventilation And Perfusion

Functional values of LogSD of the ventilation distribution (σV̇) have been reported previously, but functional values of LogSD of the perfusion distribution (σq̇) and the coefficient of correlation between ventilation and perfusion (ρ) have not been measured in humans. Here, we report values for σV̇, σq̇, and ρ obtained from wash-in data for three gases, helium and two soluble gases, acetylene and dimethyl ether. Normal subjects inspired gas containing the test gases, and the concentrations of the gases at end-expiration during the first 10 breaths were measured with the subjects at rest and at increasing levels of exercise. The regional distribution of ventilation and perfusion was described by a bivariate log-normal distribution with parameters σV̇, σq̇, and ρ, and these parameters were evaluated by matching the values of expired gas concentrations calculated for this distribution to the measured values. Values of cardiac output and LogSD ventilation/perfusion (V̇a/Q̇) were obtained. At rest, σq̇ is high (1.08 ± 0.12). With the onset of ventilation, σq̇ decreases to 0.85 ± 0.09 but remains higher than σV̇ (0.43 ± 0.09) at all exercise levels. Rho increases to 0.87 ± 0.07, and the value of LogSD V̇a/Q̇ for light and moderate exercise is primarily the result of the difference between the magnitudes of σq̇ and σV̇. With known values for the parameters, the bivariate distribution describes the comprehensive distribution of ventilation and perfusion that underlies the distribution of the V̇a/Q̇ ratio.

Voluntary induced alterations in regional ventilation in normal humans

1984 ◽  
Vol 56 (1) ◽  
pp. 196-201 ◽  
Author(s):  
M. G. Sampson ◽  
G. C. Smaldone
Keyword(s):  
Causal Relation ◽  
Normal Subjects ◽  
Washout Rate ◽  
Regional Ventilation ◽  
Lower Upper ◽  
Lower Lung ◽  
Normal Humans ◽  
Abdominal Shape ◽  
Shape Changes ◽  
133Xe Washout

We tested the hypothesis that voluntary changes of thoraco-abdominal shape can influence regional ventilation via altering regional pleural pressure swings (Ppl). Regional ventilation was measured simultaneously with regional Ppl during tidal volume breathing maneuvers in five normal subjects while they were performing one of three thoracoabdominal patterns of breathing: normal, preferential intercostal (IC), or preferential diaphragmatic (DIA). In every subject, the lower lung region's 133Xe washout rate was faster than the upper region's, regardless of the pattern of thoracoabdominal breathing adopted. Although IC breathing tended to make regional ventilation more homogeneous, DIA breathing tended to augment regional ventilation inhomogenities. On the average, the Ppl values were greatest in the lower lung region, regardless of the thoracoabdominal pattern adopted; however, IC breathing reduced and DIA breathing increased regional Ppl inhomogenities. When the ratios of the Ppl (lower/upper) were plotted vs. the ratios of the regional 133Xe washout decay constants (lower/upper), a significant positive correlation was found. These data suggest that a causal relation between regional tidal Ppl and regional ventilation exist, thus supporting the concept that thoracoabdominal shape changes can influence regional ventilation.

Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

1987 ◽  
Vol 45 ◽  
pp. 246-247
Author(s):  
R.A. Herring
Keyword(s):  
Device Fabrication ◽  
High Concentration ◽  
Tem Analysis ◽  
Defect Clusters ◽  
High Fluences ◽  
Small Defect ◽  
Before And After ◽  
The Matrix ◽  
The Difference ◽  
Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

The Effect of Stapedectomy on the Loudness of One’s Own Voice

1965 ◽  
Vol 8 (3) ◽  
pp. 223-234 ◽  
Author(s):  
William Melnick
Keyword(s):  
Middle Ear ◽  
Normal Subjects ◽  
Sound Energy ◽  
Loudness Function ◽  
Before And After ◽  
Increased Sensitivity

Five subjects with normal middle ear mechanisms, and otosclerotic patients, before and after stapedectomy, matched the loudness of their voices to the loudness of a 125-cps-sawtooth noise. The results showed loudness matching functions with gradual slopes, less than 1.00, for the normal subjects and the patients prior to stapedectomy. Post-surgically, the loudness function for the patients increased in steepness to considerably more than 1.00. These results are explained, most logically, in terms of increased sensitivity of the altered middle ear to sound energy generated by the listener’s own voice.

Changes in Platelet Aggregability after Ovariectomy

1979 ◽  
Vol 42 (04) ◽  
pp. 1332-1339 ◽  
Author(s):  
Hiroh Yamazaki ◽  
Takeshi Motomiya ◽  
Minoru Sonoda ◽  
Noboru Miyagawa
Keyword(s):  
Platelet Count ◽  
Platelet Activation ◽  
Ovarian Hormones ◽  
Control Group ◽  
Platelet Aggregability ◽  
Appearance Rate ◽  
Before And After ◽  
The Difference ◽  
Induced Aggregation ◽  
Observation Period

SummaryChanges in platelets in 48 patients with uterine myoma before and after hysterectomy with and without ovariectomy were examined. Bilateral ovariectomy in 25 cases (ovariec-tomized group) and unilateral or non-ovariectomy in 23 cases (control group) were performed at the hysterectomy. Platelet count and an appearance rate of secondary aggregation decreased at one day after and increased at one week after the operation, similarly in both the ovariectomized and the control group. The appearance rate of secondary aggregation was reflected in an intensity of aggregation at 5 min after the addition of reagent to PRP. At one month after the operation, the appearance rate of secondary aggregation induced by 3 μM ADP showed a statistically significant decrease in comparison with the preoperation value (P <0.05) and the enhancement of 5-min aggregation was still observed in the control group, while ceased in the ovariectomized group. The difference between the two groups was significant (P < 0.05). There was almost no change in the speed and intensity of primary and secondary aggregation during the observation period. No significant differences in collagen-induced aggregation were noted between the two groups. The results suggest that ovarian hormones, mainly estrogen, facilitate platelet activation which is mediated by the so-called secondary aggregation.

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