Effects of methacholine and hypocapnia on airways and collateral ventilation in dogs

1979 ◽  
Vol 46 (5) ◽  
pp. 966-972 ◽  
Author(s):  
L. J. Smith ◽  
C. R. Inners ◽  
P. B. Terry ◽  
H. A. Menkes ◽  
R. J. Traystman
Keyword(s):  
Time Constant ◽  
Fiber Optic ◽  
Small Airways ◽  
Before And After ◽  
Airways Resistance ◽  
Lung Deflation ◽  
Collateral Ventilation

We studied the effects of hypocapnia and methacholine on small airways resistance (Rsaw) and collateral ventilation in anesthetized paralyzed dogs. The animals were ventilated with air while either 10% CO2 or air (hypocapnia) was infused through a segment obstructed with a fiber-optic bronchoscope. Measurements were made before and after instillation of methacholine into the obstructed segment. Collateral resistance (Rcoll) and Rsaw increased with hypocapnia and methacholine. The time constant for collateral ventilation increased with hypocapnia, but did not change with methacholine because of decreases in the compliance of the obstructed segment. We conclude that collateral channels respond to methacholine and hypocapnia in a manner similar to small airways and that local parasympathomimetic stimulation, unlike lung deflation does not increase the time constant for collateral ventilation.

Effect of lung volume on collateral ventilation in the dog

1980 ◽  
Vol 49 (1) ◽  
pp. 9-15 ◽  
Author(s):  
J. Kaplan ◽  
R. C. Koehler ◽  
P. B. Terry ◽  
H. A. Menkes ◽  
R. J. Traystman
Keyword(s):  
Lung Volume ◽  
Transpulmonary Pressure ◽  
Relative Increase ◽  
Small Airways ◽  
Lung Inflation ◽  
Before And After ◽  
Collateral Pathways ◽  
Flow Through ◽  
Collateral Ventilation

We studied the effect of lung volume on resistance through collateral pathways (Rcoll) and small airways (Rsaw) before and after the injection of methacholine into obstructed segments of intact dogs. Before methacholine, Rcoll decreased 15.0 ± 4.9 (SE)% per cmH2O increase in transpulmonary pressure (Ptp) and Rsaw decreased 5.1 ± 7.0 (SE)% per cmH2O increase in Ptp. Following methacholine, lung inflation resulted in similar decreases in Rcoll and Rsaw. The fall in Rcoll was significantly greater than the fall in Rsaw. When pressure in an obstructed segment (Ps) was increased with constant Ptp (nonhomogeneous inflation), Rcoll fell approximately half as much for each cmH2O increase in pressure compared to when Ptp was increased (homogeneous inflation). We conclude 1) that increases in lung volume have small effects on Rsaw so that there is a relative increase in flow through collateral channels serving obstructed poritons of lung and 2) that Rcoll is a function of the size of the obstructed segment that increases more under homogeneous than nonhomogeneous conditions.

Effects of atropine on potentiation of exercise-induced bronchospasm by cold air

1978 ◽  
Vol 45 (2) ◽  
pp. 238-243 ◽  
Author(s):  
E. C. Deal ◽  
E. R. McFadden ◽  
R. H. Ingram ◽  
J. J. Jaeger
Keyword(s):  
Ambient Air ◽  
Small Airways ◽  
Flow Limitation ◽  
Ambient Conditions ◽  
Cold Air ◽  
Relative Contribution ◽  
Maximal Expiratory Flow ◽  
Before And After ◽  
Expiratory Flow ◽  
Exercise Induced

The role of vagal efferent activity in the cold air potentiation of exercise-induced asthma was assessed by exercising nine subjects who breathed air at ambient and subfreezing temperatures before and after cholinergic blockade. Lung volumes and maximal expiratory flow volume curves with air and with 80% helium-20% oxygen were obtained before and 5--10 min after each challenge. Isovolume comparisons of maximal expiratory flow rates with the two gases were used to assess relative contributions of large and small airways to flow limitation. Exercise under ambient conditions resulted in the expected airway obstruction and cold air exaggerated the response. Atropine pretreatment had no effect on the cold air potentiation. After atropine with ambient air exercise, there was an increase in the relative contribution of large airways to flow limitation, whereas exercise with cold air resulted in an increase in the contribution of small airways. We concluded that the potentiating effects of cold air are local and suggest that the immediate stimulus is related to cooling of intrathoracic airways.

Local regulation of collateral ventilation by oxygen and carbon dioxide

1976 ◽  
Vol 40 (5) ◽  
pp. 819-823 ◽  
Author(s):  
R. J. Traystman ◽  
G. K. Batra ◽  
H. A. Menkes
Keyword(s):  
Carbon Dioxide ◽  
Time Constant ◽  
Local Level ◽  
Co2 Concentration ◽  
The Other ◽  
Constant Flow ◽  
Local Regulation ◽  
Peripheral Airway ◽  
Residual Capacity ◽  
Collateral Ventilation

The effects of changes in CO2 and O2 on the mechanics of collateral ventilation were studied in anesthetized paralyzed dogs. A doublelumen catheter was wedged into a peripheral airway obstructing a segment of lung distal to the catheter. Through one lumen of the catheter, air, 5% CO2 in air, 10% CO2 in air, 5% O2 in N2, or 5% CO2 in N2 was infused at a constant flow (V). Pressure (Ps) was monitored through the other lumen. At functional residual capacity the resistance to collateral flor Rcoll = Ps/V. When V was interrrupted , the time for Ps to fall 63% was defined as the time constant for collateral ventilation, Tcoll. The effective compliance (Cs′) = Tcoll/Rcoll. When air was replaced by 5% CO2, Rcoll fell 46.3% (+/- SE 2.8) and Tcoll fell 41.5% (+/- SE 3.0). When the CO2 concentration was increased from 5% to 10%, Rcoll fell an additional 9.2% (+/- SE 2.2) and Tcoll fell an additional 5.1% (+/- SE 4.4). When air was replaced by 5% O2 in N2, Rcoll rose 36.6% (+/- SE 6.0) and Tcoll rose 13.6% (+/- SE 10.5). No significant changes in Cs′ were noted. We conclude that varying concentrations of CO2 and O2 provide potent mechanisms for the control of collateral ventillation which may be of importance in the regulation of ventillation perfusion relationships at the local level.

Reversibility of Airways Obstruction in Chronic Bronchitis

1972 ◽  
Vol 42 (6) ◽  
pp. 725-733 ◽  
Author(s):  
T. W. Astin
Keyword(s):  
Muscle Contraction ◽  
Chronic Bronchitis ◽  
Lung Volume ◽  
Normal Subjects ◽  
Atropine Sulphate ◽  
Airways Obstruction ◽  
Chest Disease ◽  
Before And After ◽  
Airways Resistance ◽  
Intravenous Atropine

1. Airways resistance and lung volume were measured in twenty-five patients with chronic bronchitis and fifteen patients without chest disease before and after the inhalation of isoprenaline. Similar measurements were made on fourteen of these patients with chronic bronchitis and twelve other patients without chest disease before and after the intravenous injection of atropine sulphate. 2. There were significant decreases in airways resistance after isoprenaline inhalation and intravenous atropine both in patients with bronchitis and normal subjects but the decreases were greater in the patients with chronic bronchitis. 3. The decrease in resistance was proportional to the degree of initial airways resistance. 4. The results are considered to indicate that bronchial muscle contraction increases the airways resistance of patients with chronic bronchitis and contributes to the airways obstruction; its contribution increases with increasing severity of the condition. A significant part of the increased airways resistance in these patients is potentially reversible and nervously mediated.

Small airways function in breast cancer patients before and after radiotherapy

2012 ◽  
Vol 135 (3) ◽  
pp. 857-865 ◽  
Author(s):  
Sylvia Verbanck ◽  
Shane Hanon ◽  
Daniel Schuermans ◽  
Hilde Van Parijs ◽  
Vincent Vinh-Hung ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Patients ◽  
Small Airways ◽  
Breast Cancer Patients ◽  
Before And After

scholarly journals Quantification ofin vivocolonic motor patterns in healthy humans before and after a meal revealed by high-resolution fiber-optic manometry

2014 ◽  
Vol 26 (10) ◽  
pp. 1443-1457 ◽  
Author(s):  
P. G. Dinning ◽  
L. Wiklendt ◽  
L. Maslen ◽  
I. Gibbins ◽  
V. Patton ◽  
...  
Keyword(s):  
High Resolution ◽  
Fiber Optic ◽  
Motor Patterns ◽  
Healthy Humans ◽  
Before And After

The Interpretation of Different Measurements of Airways Obstruction in the Presence of Lung Volume Changes in Bronchial Asthma

1978 ◽  
Vol 54 (3) ◽  
pp. 313-321
Author(s):  
K. B. Saunders ◽  
M. Rudolf
Keyword(s):  
Lung Volume ◽  
Time Course ◽  
Forced Expiratory Volume ◽  
Specific Conductance ◽  
Volume Changes ◽  
Lung Volumes ◽  
Bronchodilator Response ◽  
Before And After ◽  
Residual Capacity ◽  
Airways Resistance

1. We measured changes in peak expiratory flow rate (PEFR), forced expiratory volume in 1 s (FEV1·0), airways resistance (Raw), specific conductance (sGaw), residual volume (RV), functional residual capacity (FRC) and total lung capacity (TLC) in 44 patients with asthma. 2. When asthma was induced by exercise in five patients there were large changes in volumes, but these did not obscure changes in PEFR, which adequately defined the time course of the response. 3. In 70 comparisons before and after inhalation of bronchodilator drug in 33 asthmatic subjects, the responses were classified by the size of the change in lung volumes, which showed a concordant improvement, or no change, in 61 comparisons. Despite these lung volume changes, measurement of both PEFR and FEV1·0, would have detected a bronchodilator response in all but two cases. 4. In 81 comparisons in 23 subjects over time intervals varying from 1 day to 11 months, lung volumes changed in concordance with PEFR and FEV1·0 in 59. In eight of these comparisons, measurement of lung volumes would have altered our interpretation of the changes in PEFR and FEV1·0. 5. In the same 81 comparisons changes in airways resistance were concordant with changes in PEFR and FEV1·0 on 44 occasions, with minor discordant changes in 19. We could not explain the remaining 18 cases showing major discordance between these two types of measurement of airway calibre. 6. We conclude that both FEV1·0, and PEFR should be used for detection of a bronchodilator response, and that measurement of lung volumes will rarely contribute to the interpretation. Over longer periods, lung volumes should be measured if possible. We found no practical use for routine measurement of airways resistance in patients with asthma.

scholarly journals Use thermophysical property to quantify state of HIFU treatment for VLS

2020 ◽  
Vol 185 ◽  
pp. 03045
Author(s):  
Sui Feng ◽  
Yingjie Qu ◽  
Yuquan Meng ◽  
Jinjin Zheng
Keyword(s):  
Time Constant ◽  
Lichen Sclerosus ◽  
Assessment Method ◽  
High Intensity Focused Ultrasound ◽  
Thermal Time ◽  
Inflammatory Disorder ◽  
Hifu Treatment ◽  
Thermal Time Constant ◽  
Increased Risk ◽  
Before And After

The aim of this study is to evaluate the performance of ADT methods in grading the effectiveness of HIFU treatment for VLS. High-intensity focused ultrasound has been identified as a promising treatment modality for vulvar lichen sclerosus, a common inflammatory disorder associated with an increased risk of developing vulvar carcinoma. With small probe on extensive VLS parts, the therapy was sometimes uneven, thus the total doses of HIFU machine couldn’t indicate the curative effect at each part. The current therapeutic effect was based on symptoms and skin appearance after 3 months, which was time-consuming. Until now, there has been no immediate quantitative assessment method of HIFU therapeutic response for VLS. In our study, active dynamic IR thermal (ADT) was scheduled to undergo HIFU therapy before and after treatment. The thermal time constant was calculated based on ADT images measured both before and after HIFU treatment. In the result of pig phantom measurements, with each part approximately the same thermal time constant before HIFU treatment, the change of thermal time constant was strictly positively associated with HIFU dose onto each part. This study demonstrates the clinical potential of ADT in fast and effective quantify state of HIFU treatment for VLS.

Canine pulmonary response to aerosol histamine: direct versus vagal effects

1977 ◽  
Vol 42 (6) ◽  
pp. 946-952 ◽  
Author(s):  
S. H. Loring ◽  
J. M. Drazen ◽  
R. H. Ingram
Keyword(s):  
Sulfur Hexafluoride ◽  
Dynamic Compliance ◽  
Minor Role ◽  
Small Airways ◽  
Pulmonary Response ◽  
Aerosol Generator ◽  
Vagal Blockade ◽  
Aerosol Exposure ◽  
Before And After ◽  
Dose Dependent

Histamine, a potent bronchoconstrictor, has been shown to produce bronchoconstriction both directly and by a vagal reflex. To define the relative roles of direct and reflex effects, we studied the pulmonary response of dogs exposed to increasing doses of aerosol histamine before and after vagal blockade or vagotomy. In addition, the relative contributions of aerodynamically large and small airways to the overall response were determined by the measurement of pulmonary resistance on sulfur hexafluoride-oxygen and helium-oxygen mixtures. Histamine aerosol caused a similar dose-dependent increase in resistance of aerodynamically large and small airways and fall in dynamic compliance. The dose-response relationships were not consistently altered by either vagal blockade or vagotomy. The following variables were found not to alter the experimental results: anesthesia, type of aerosol generator, control of breathing during aerosol exposure, spontaneous breathing vs. controlled ventilation after aerosol exposure, cold block of vagi vs. vagotomy. We conclude that 1) histamine aerosol in dogs causes a local dose-dependent constriction of bronchial smooth muscle, and 2) the vagus nerve played a relatively minor role in the pulmonary response to aerosol histamine in these experiments.

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