Maximal Expiratory Flow and Lung Volume Changes Associated with Exercise-Induced Asthma in Children and the Effect of Breathing a Low-Density Gas Mixture

1974 ◽  
Vol 46 (3) ◽  
pp. 317-329 ◽  
Author(s):  
S. R. Benatar ◽  
P. König
Keyword(s):  
Flow Rate ◽  
Vital Capacity ◽  
Forced Expiratory Volume ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Lung Volumes ◽  
Flow Rates ◽  
Before And After ◽  
Expiratory Flow

1. Lung volumes and maximum expiratory flow volume (MEFV) curves were measured before and after exercise and after a bronchodilator in eight asthmatic children. 2. Exercise produced significant changes in all volumes and flow rates measured, but the most sensitive measurement was of flow rate at an absolute volume in the terminal portion of the forced vital capacity. Of the more simply obtained measurements maximal flow at 50% of the exhaled vital capacity was the most sensitive, but reductions in forced expiratory volume at 1 s and peak flow rate were almost as marked. 3. The marked reductions in flow rates at low lung volumes after exercise were accompanied by large increases in residual volume and a reduction in the slope of the MEFV curve. These changes suggest functional closure of some lung units and an increase in the time-constant of emptying of other units. 4. The response of flow to breathing helium—oxygen (79:21, v/v) was assessed in the dilated state (before exercise or after bronchodilator) and the constricted state (after exercise) in five of the subjects. 5. An increase in density-dependence of flow rates at all lung volumes during constriction is evidence that, despite the reduction in flow rates, convective acceleration and turbulent flow constitute a greater proportion of the total upstream resistance after exercise than before exercise. The implication is that the cross-sectional area at equal pressure points (EPP) is smaller after exercise than before exercise. This could result from either bronchoconstriction with no change in the location of EPP, or from progression of the EPP further upstream to a region where loss of airways or reduction in their diameter has rendered the total cross-sectional area considerably smaller than under normal circumstances.

Physiology of Cough

1974 ◽  
Vol 83 (6) ◽  
pp. 761-768 ◽  
Author(s):  
P. T. MacKlem
Keyword(s):  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Lung Volumes ◽  
Flow Rates ◽  
Velocity Flow ◽  
Large Airways ◽  
Total Cross Sectional Area ◽  
Expiratory Flow ◽  
Expiratory Flow Rates

The effectiveness of cough depends upon the linear velocity of the gas in the airways. Because velocity = flow/cross-sectional area, a high flow and a small cross-section are the ideal conditions for an effective cough. Pleural pressures become positive during cough and compress the large airways producing a marked reduction in cross-sectional area. At high lung volumes, expiratory flow rates are high so that the linear velocities in the trachea are approximately one-third of the speed of sound. The velocity falls in higher bronchial generations, both because the total cross-sectional area of each generation becomes progressively larger beyond the lobar bronchi, and because at high volumes the compressed segment of the airway only extends from the lobar bronchi to the thoracic outlet of the trachea. In normal lungs cough is effective in clearing secretions from these airways only. In chronic bronchitis and emphysema, expiratory flow rates are markedly reduced. Furthermore, in some cases the large airways are more easily compressed than normal. This results in a shorter segment of the airway being compressed. For both reasons, the efficiency of cough is markedly decreased leading to retention of secretions. In cystic and varicose bronchiectasis the problem is different. There is no flow through the bronchiectatic segments because they are blind sacs, and the efficiency of cough is independent of the velocity. To empty them of their secretions is analogous to squeezing toohpaste out of a tube. This is theoretically possible at low lung volumes when the compressed segment is longer.

Relationship of ventilatory capacity to hyperbaric exposure in divers

1984 ◽  
Vol 56 (6) ◽  
pp. 1655-1658 ◽  
Author(s):  
I. S. Davey ◽  
J. E. Cotes ◽  
J. W. Reed
Keyword(s):  
Flow Rate ◽  
Vital Capacity ◽  
Positive Association ◽  
Forced Expiratory Volume ◽  
Elastic Tissue ◽  
Significant Positive Association ◽  
Cross Sectional ◽  
Maximal Depth ◽  
Forced Expiratory Flow ◽  
Expiratory Flow

The results of divers' annual medical examinations were used to assess the effects of diving exposure independent of age, stature, and smoking on forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). Cross-sectional analysis of records for 858 men showed a significant positive association between the maximal depth that subjects had experienced and FVC but not FEV1. There was a significant negative association for FEV1/FVC%, and this index was also positively correlated with years of diving exposure. Among a subsample of 81 men the forced expiratory flow rate at low lung volume was reduced relative to that of control subjects similarly assessed; the extent of the reduction from the reference value was significantly correlated with the diving exposure. Longitudinal analysis of results for 255 men over a minimum of 5 yr showed that the change in FVC per annum (positive or negative) was correlated with the change in maximal depth; there were no similar associations for FEV1 or FEV1/FVC%. Thus diving exposure affects the vital capacity and the forced expiratory flow rate at small lung volumes. The latter is evidence for narrowing of airways that might be secondary to diving-induced loss of lung elastic tissue; this hypothesis merits further investigation.

Changes in Speech Breathing Following Cochlear Implant in Postlingually Deafened Adults

1991 ◽  
Vol 34 (3) ◽  
pp. 526-533 ◽  
Author(s):  
Harlan Lane ◽  
Joseph Perkell ◽  
Mario Svirsky ◽  
Jane Webster
Keyword(s):  
Cochlear Implants ◽  
Flow Rate ◽  
Low Flow ◽  
Average Flow Rate ◽  
Cross Sectional ◽  
Lung Volumes ◽  
Flow Rates ◽  
Average Value ◽  
Speech Breathing ◽  
Before And After

Three postlingually deafened adults who received cochlear implants read passages before and after their prostheses were activated while their lung volumes were measured with an Inductive plethysmograph that transduced the cross-sectional areas of the speaker’s chest and abdomen. Lung volumes at the initiation and termination of the speakers’ expiratory limbs, their average air flow, and the volume of air they expended per syllable were derived from tracings of calibrated lung volume displayed by computer. The activation of the speakers’ cochlear prostheses was followed in every case by a significant change in average airflow, which rose for two subjects with initially low flow rates and fell for one subject who had a much higher average preimplant flow rate. These changes in average flow rate were accompanied by corresponding changes in volume of air expended per syllable, statistically reliable in two of the three cases. There were no significant changes in the levels at which speakers initiated their expiratory limbs, but one speaker, after his prosthesis was activated, reliably increased the level of air in his lungs at the end of expiratory limbs to an average value that no longer required him to draw on expiratory reserve volume.

scholarly journals Quantitative magnetic resonance image assessment of the optic nerve and surrounding sheath after spaceflight

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Jesse J. Rohr ◽  
Stuart Sater ◽  
Austin M. Sass ◽  
Karina Marshall-Goebel ◽  
Robert J. Ploutz-Snyder ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Magnetic Resonance ◽  
Recovery Period ◽  
Space Station ◽  
Cross Sectional Area ◽  
Quantitative Mri ◽  
Sectional Area ◽  
Cross Sectional ◽  
Before And After ◽  
Increased Icp

Abstract A subset of long-duration spaceflight astronauts have experienced ophthalmic abnormalities, collectively termed spaceflight-associated neuro-ocular syndrome (SANS). Little is understood about the pathophysiology of SANS; however, microgravity-induced alterations in intracranial pressure (ICP) due to headward fluid shifts is the primary hypothesized contributor. In particular, potential changes in optic nerve (ON) tortuosity and ON sheath (ONS) distension may indicate altered cerebrospinal fluid dynamics during weightlessness. The present longitudinal study aims to provide a quantitative analysis of ON and ONS cross-sectional areas, and ON deviation, an indication of tortuosity, before and after spaceflight. Ten astronauts undergoing ~6-month missions on the International Space Station (ISS) underwent high-resolution magnetic resonance imaging (MRI) preflight and at five recovery time points extending to 1 year after return from the ISS. The mean changes in ON deviation, ON cross-sectional area, and ONS cross-sectional area immediately post flight were −0.14 mm (95% CI: −0.36 to 0.08, Bonferroni-adjusted P = 1.00), 0.13 mm2 (95% CI −0.66 to 0.91, Bonferroni-adjusted P = 1.00), and −0.22 mm2 (95% CI: −1.78 to 1.34, Bonferroni-adjusted P = 1.00), respectively, and remained consistent during the recovery period. Terrestrially, ONS distension is associated with increased ICP; therefore, these results suggest that, on average, ICP was not pathologically elevated immediately after spaceflight. However, a subject diagnosed with optic disc edema (Frisen Grade 1, right eye) displayed increased ONS area post flight, although this increase is relatively small compared to clinical populations with increased ICP. Advanced quantitative MRI-based assessment of the ON and ONS could help our understanding of SANS and the role of ICP.

Pulmonary Vessel Cross-sectional Area before and after Liver Transplantation

2015 ◽  
Vol 22 (6) ◽  
pp. 752-759
Author(s):  
Hilary M. DuBrock ◽  
Alexander A. Bankier ◽  
Mario Silva ◽  
Diana E. Litmanovich ◽  
Michael P. Curry ◽  
...  
Keyword(s):  
Liver Transplantation ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Pulmonary Vessel ◽  
Before And After

Accuracy and precision of MR velocity mapping in measurement of stenotic cross-sectional area, flow rate, and pressure gradient

1993 ◽  
Vol 3 (2) ◽  
pp. 433-437 ◽  
Author(s):  
Lars Søndergaard ◽  
Freddy Ståhlberg ◽  
Carsten Thomsen ◽  
Anders Stensgaard ◽  
Knud Lindvig ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Flow Rate ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Velocity Mapping ◽  
Cross Sectional ◽  
Accuracy And Precision

Density-Dependence of Maximal Expiratory Flow Rates before and after Bronchodilators in Patients with Obstructive Airways Disease

1976 ◽  
Vol 51 (2) ◽  
pp. 133-139
Author(s):  
J. J. Wellman ◽  
E. R. McFadden ◽  
R. H. Ingram
Keyword(s):  
Density Dependence ◽  
Lung Volumes ◽  
Flow Rates ◽  
Maximal Expiratory Flow ◽  
Before And After ◽  
Group A ◽  
Obstructive Airways Disease ◽  
Expiratory Flow ◽  
Group B ◽  
Expiratory Flow Rates

1. Gas-density-dependence of maximal expiratory flow rates (V̇max), defined as the ratio of V̇max while breathing helium/oxygen (80:20) to V̇max. while breathing air at the same lung volume, was examined in relation to other measurements of airways obstruction in patients with obstructive airways disease before and after administration of bronchodilators. 2. Seventeen patients showed a 45% or greater increase in specific conductance(sGaw) after bronchodilator therapy (group A) and thirteen patients demonstrated a lesser response (group B). 3. Before the administration of bronchodilators, the degree of obstruction in the two groups was not different as measured by lung volumes, sGaw, forced expiratory volume in 1 s, and flow rates high in the vital capacity; yet the maximal mid-expiratory flow rate and the degree of density-dependence were significantly lower in group B. 4. After bronchodilators, both groups of patients showed significant improvements in sGaw flow rates and lung volumes. However, group A patients showed a significant increase in density-dependence whereas group B patients did not. 5. Increased density-dependence after bronchodilators in the group A patients was associated with an increase in the computed resistance of the upstream segment with air and a decrease in resistance with helium/oxygen. These changes could be explained by a more mouthward movement of equal pressure points, and therefore a further increase in the relative contribution of the larger density-dependent airways to limitation of flow. 6. The fact that density-dependence was not altered after bronchodilators in the group B patients suggests that the site of limitation of flow did not change appreciably. The shift in the pressure—flow curve for the upstream airways was such that the computed resistance of these airways fell. Thus it appears that the airways comprising the upstream segment were dilated.

Infraspinatus Cross-Sectional Area and Shoulder Range of Motion Change Following Live-Game Baseball Pitching

2019 ◽  
Vol 28 (3) ◽  
pp. 236-242 ◽  
Author(s):  
Brett S. Pexa ◽  
Eric D. Ryan ◽  
Elizabeth E. Hibberd ◽  
Elizabeth Teel ◽  
Terri Jo Rucinski ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Athletic Training ◽  
Repeated Measures ◽  
External Rotation ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Shoulder Range Of Motion ◽  
Posterior Shoulder ◽  
Before And After

Context: Following a baseball pitching bout, changes can occur to glenohumeral range of motion that could be linked to injury. These effects are in part due to the posterior shoulder’s eccentric muscle activity, which can disrupt muscle contractile elements and lead to changes in muscle cross-sectional area (CSA), as measured by ultrasound. Objective: To assess changes in muscle CSA, and range of motion immediately before and after pitching, and days 1 to 5 following pitching. Design: Repeated measures. Setting: Satellite athletic training room. Patients: Ten elite college baseball pitchers participating in the fall season (age: 18.8 [1.2] y, height: 189.2 [7.3] cm, mass: 93.1 [15.3] kg, 8 starters, 2 long relievers). Intervention: A pitching bout of at least 25 pitches (63.82 [17.42] pitches). Main Outcome Measures: Dominant and nondominant infraspinatus CSA, as measured by ultrasound, and glenohumeral range of motion including internal rotation (IRROM), external rotation (ERROM), and total rotation range of motion (TROM) before pitching, after pitching, and days 1 to 5 following the pitching bout. Results: Dominant limb CSA significantly increased day 1 after pitching, and returned to baseline on day 2 (P < .001). Dominant and nondominant TROM did not change until day 5 (4.4°, P < .001) and day 3 (4.5°, P < .001), respectively, where they increased. Dominant IRROM was significantly decreased for 3 days (day 1: 1.9°, P < .001; day 2: 3.1°, P < .001; day 3: 0.3°, P < .001) following pitching and returned to baseline on day 4, with no such changes in the nondominant limb. Dominant external rotation significantly increased immediately post pitching (4.4°, P < .001) but returned to baseline by day 1. Conclusions: The results of the study demonstrate that infraspinatus CSA does not recover until 2 days following pitching, and IRROM does not recover until 4 days following pitching. Baseball pitching elicits damage to the posterior shoulder muscle architecture, resulting in changes to physical characteristics that last up to 4 days following pitching.

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