Interdependence of regional expiratory flow

1985 ◽  
Vol 59 (6) ◽  
pp. 1924-1928 ◽  
Author(s):  
T. A. Wilson ◽  
J. J. Fredberg ◽  
J. R. Rodarte ◽  
R. E. Hyatt
Keyword(s):  
Lung Volume ◽  
Regional Differences ◽  
Vital Capacity ◽  
Maximum Flow ◽  
Bronchial Tree ◽  
Lung Compliance ◽  
Junction Flow ◽  
Expiratory Flow ◽  
The Difference ◽  
Limiting Pressure

Flows from different lung regions interact at the junctions of the bronchial tree, and flow from each region depends on the driving pressures for other regions. At each junction, flow from the region with the higher driving pressure is favored. As a result there is a limit on the difference in alveolar pressures that can develop during expiratory flow from a lung with regional differences in lung compliance and airway resistance. The limiting pressure difference is smaller for lower flow. A nonuniform lung therefore empties more uniformly if it empties slowly, and maximum flow at low lung volume may be greater than it would be at the same lung volume during a maximal expiratory vital capacity maneuver.

Breathing at low lung volumes and chest strapping: a comparison of lung mechanics

1981 ◽  
Vol 50 (3) ◽  
pp. 650-657 ◽  
Author(s):  
N. J. Douglas ◽  
G. B. Drummond ◽  
M. F. Sudlow
Keyword(s):  
Lung Volume ◽  
Maximum Flow ◽  
Normal Subjects ◽  
Lung Mechanics ◽  
Lung Volumes ◽  
Flow Rates ◽  
Recoil Pressure ◽  
Forced Expiratory Flow ◽  
Expiratory Flow ◽  
Expiratory Flow Rates

In six normal subjects forced expiratory flow rates increased progressively with increasing degrees of chest strapping. In nine normal subjects forced expiratory flow rates increased with the time spent breathing with expiratory reserve volume 0.5 liters above residual volume, the increase being significant by 30 s (P less than 0.01), and flow rates were still increasing at 2 min, the longest time the subjects could breathe at this lung volume. The increase in flow after low lung volume breathing (LLVB) was similar to that produced by strapping. The effect of LLVB was diminished by the inhalation of the atropinelike drug ipratropium. Quasistatic recoil pressures were higher following strapping and LLVB than on partial or maximal expiration, but the rise in recoil pressure was insufficient to account for all the observed increased in maximum flow. We suggest that the effects of chest strapping are due to LLVB and that both cause bronchodilatation.

OBSTRUCTIVE DISEASE OF THE AIRWAYS IN CYSTIC FIBROSIS

PEDIATRICS ◽  
1968 ◽  
Vol 41 (3) ◽  
pp. 560-573
Author(s):  
Robert B. Mellins ◽  
O. Robert Levine ◽  
Roland H. Ingram ◽  
Alfred P. Fishman
Keyword(s):  
Cystic Fibrosis ◽  
Vital Capacity ◽  
Maximum Flow ◽  
Transpulmonary Pressure ◽  
Forced Expiration ◽  
Lung Volumes ◽  
Flow Rates ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow ◽  
Expiratory Flow Rates

A study of the interrelationships of instantaneous air flow, lung volume, and transpulmonary pressure over the range of the vital capacity has demonstrated striking differences in the determinants of maximum expiratory flow in cystic fibrosis and asthma. At high lung volumes, maximum expiratory flow rates in asthma are limited by the mechanical characteristics of the lungs and airways, whereas in cystic fibrosis and in the normal they are dependent on effort. At lower lung volumes, maximum expiratory flow rates are relatively more reduced in cystic fibrosis than in asthma and pressures in excess of those required to produce maximum flow actually depress flow. Also, forced expiration is associated with a transient reversal in the slope of the single breath nitrogen curve in cystic fibrosis and not in asthma. From these studies it is concluded that: (1) airway obstruction is less uniform and involves larger airways in cystic fibrosis than in asthma, and (2) increased expiratory pressure is associated with collapse of some of the larger airways over most of the range of the vital capacity in cystic fibrosis. A major clinical implication of these studies is that the effectiveness of cough is impaired by large airway collapse in cystic fibrosis.

Heterogeneous airway tone in asthmatic subjects

1992 ◽  
Vol 73 (6) ◽  
pp. 2328-2332 ◽  
Author(s):  
G. Julia-Serda ◽  
N. A. Molfino ◽  
K. R. Chapman ◽  
P. A. McClean ◽  
N. Zamel ◽  
...  
Keyword(s):  
Lung Volume ◽  
Vital Capacity ◽  
Total Lung Capacity ◽  
Lung Parenchyma ◽  
Flow Volume ◽  
Lung Capacity ◽  
Group I ◽  
Expiratory Flow ◽  
Airway Tone ◽  
Volume History

We examined the effect of volume history on the dynamic relationship between airways and lung parenchyma (relative hysteresis) in 20 asthmatic subjects. The acoustic reflection technique was employed to evaluate changes in airway cross-sectional areas during a slow continuous expiration from total lung capacity to residual volume and inspiration back to total lung capacity. Lung volume was measured continuously during this quasi-static maneuver. We studied three anatomic airway segments: extra- and intrathoracic tracheal and main bronchial segments. Plots of airway area vs. lung volume were obtained for each segment to assess the relative magnitude and direction of the airway and parenchymal hysteresis. We also performed maximal expiratory flow-volume and partial expiratory flow-volume curves and calculated the ratio of maximal to partial flow rates (M/P) at 30% of the vital capacity. We found that 10 subjects (group I) showed a significant predominance of airway over parenchymal hysteresis (P < 0.005) at the extra- and intrathoracic tracheal and main bronchial segments; these subjects had high M/P ratios [1.53 +/- 0.27 (SD)]. The other 10 subjects (group II) showed similar airway and parenchymal hysteresis for all three segments and significantly lower M/P ratios (1.16 +/- 0.20, P < 0.01). We conclude that the effect of volume history on the relative hysteresis of airway and lung parenchyma and M/P ratio at 30% of vital capacity in nonprovoked asthmatic subjects is variable. We suggest that our findings may result from heterogeneous airway tone in asthmatic subjects.

Trachea and lung dimensions in nonsmoking twins: morphological and functional studies

1986 ◽  
Vol 61 (2) ◽  
pp. 495-499 ◽  
Author(s):  
Y. Kawakami ◽  
H. Kusaka ◽  
M. Nishimura ◽  
S. Abe
Keyword(s):  
Forced Vital Capacity ◽  
Vital Capacity ◽  
Genetic Factors ◽  
Maximum Flow ◽  
Forced Expiratory Volume ◽  
Phase Iii ◽  
Closing Volume ◽  
Residual Volume ◽  
Capacity Ratio ◽  
Expiratory Flow

To compare genetic and environmental factors that determine lung function and dimensions, chest radiographs and pulmonary function were measured in 17 pairs of nonsmoking twin adolescent boys (12 monozygotic pairs and 5 dizygotic pairs). Genetic factors dominated in tracheal width and lung dimensions (height, width, and apicofissural and fissurodiaphragmatic distances) at residual volume. Genetic factors also affected forced vital capacity, functional residual capacity, forced expiratory volume in 1 s, maximum expiratory flow at 25% vital capacity, and maximum flow at 50% vital capacity-to-forced vital capacity ratio. Peak expiratory flow correlated with tracheal width at residual volume. Age correlated with lung dimensions (width and depth) but not with tracheal width. These results indicate that genetic factors determine the dimensions and function of central airways, peripheral airways, and lung parenchyma in adolescent males. The effects of genetic factors on some functional measurements (airway resistance, closing volume-to-vital capacity ratio, and phase III in single-breath N2 washout) may be masked because of poor reproducibility of the tests.

Increased gravitational stress does not alter maximum expiratory flow

1985 ◽  
Vol 59 (1) ◽  
pp. 28-33 ◽  
Author(s):  
D. Pyszczynski ◽  
S. N. Mink ◽  
N. R. Anthonisen
Keyword(s):  
Vital Capacity ◽  
Total Lung Capacity ◽  
Maximum Flow ◽  
Flow Volume ◽  
Lung Capacity ◽  
Gravitational Stress ◽  
Regional Lung ◽  
Maximum Expiratory Flow ◽  
Expiratory Flow ◽  
Capacity Data

We measured maximum expiratory flow-volume (MEFV) curves in six seated subjects during normal (+1 Gz) and increased (+2 and +3 Gz) gravitational stress. Full MEFV curves, initiated at total lung capacity, were recorded, as were partial MEFV curves, initiated at approximately 60% of the vital capacity. Data were acquired in all subjects breathing air at +1 and +2 Gz; results were available for three subjects breathing 80% He-20% O2 at +1 and +2 Gz, and in two subjects, results were obtained at +3 Gz. Changes in gravitational stress were not associated with changes of either full or partial MEFV curves. The known increase in differences of regional lung volume and recoil caused by increased gravitational stress did not influence maximum expiratory flow. Though increased gravitational stress probably changed regional emptying sequences little during full MEFV maneuvers, substantial changes of emptying sequence were expected during partial maneuvers. It is possible that such changes in emptying sequence occurred but were not associated with changes in maximum flow because the latter was determined by choking in central airways common to all regions.

No effect of artificial gravity on lung function with exercise training during head-down bed rest

2015 ◽  
pp. 1-7
Author(s):  
Longxiang Su ◽  
Yinghua Guo ◽  
Yajuan Wang ◽  
Delong Wang ◽  
Changting Liu
Keyword(s):  
Lung Function ◽  
Pulse Rate ◽  
Vital Capacity ◽  
Pulmonary Ventilation ◽  
Bed Rest ◽  
Forced Expiratory Volume ◽  
Observation Time ◽  
Artificial Gravity ◽  
Postural Changes ◽  
Expiratory Flow

AbstractTo explore the effectiveness of microgravity simulated by head-down bed rest (HDBR) and artificial gravity (AG) with exercise on lung function. Twenty-four volunteers were randomly divided into control and exercise countermeasure (CM) groups for 96 h of 6° HDBR. Comparisons of pulse rate, pulse oxygen saturation (SpO2) and lung function were made between these two groups at 0, 24, 48, 72, 96 h. Compared with the sitting position, inspiratory capacity and respiratory reserve volume were significantly higher than before HDBR (0° position) (P&lt; 0.05). Vital capacity, expiratory reserve volume, forced vital capacity, forced expiratory volume in 1 s, forced inspiratory vital capacity, forced inspiratory volume in 1 s, forced expiratory flow at 25, 50 and 75%, maximal mid-expiratory flow and peak expiratory flow were all significantly lower than those before HDBR (P&lt; 0.05). Neither control nor CM groups showed significant differences in the pulse rate, SpO2, pulmonary volume and pulmonary ventilation function over the HDBR observation time. Postural changes can lead to variation in lung volume and ventilation function, but a HDBR model induced no changes in pulmonary function and therefore should not be used to study AG CMs.

scholarly journals Regional differences in mortality rates during the COVID-19 epidemic in Italy

2020 ◽  
pp. 1-22
Author(s):  
Danila Azzolina ◽  
Giulia Lorenzoni ◽  
Luciano Silvestri ◽  
Ilaria Prosepe ◽  
Paola Berchialla ◽  
...  
Keyword(s):  
Regional Differences ◽  
Southern Italy ◽  
Meta Analysis ◽  
Analysis Data ◽  
Mortality Rates ◽  
Northern Italy ◽  
Admission Rates ◽  
Considerable Impact ◽  
The Difference ◽  
Disease Diffusion

Abstract Objective The COVID-19 outbreak started in Italy on February 20th, 2020, and has resulted in many deaths and intensive care unit (ICU) admissions. This study aimed to illustrate the epidemic COVID-19 growth pattern in Italy by considering the regional differences in disease diffusion during the first three months of the epidemic. Study design and methods Official COVID-19 data were obtained from the Italian Civil Protection Department of the Council of Ministers Presidency. The mortality and ICU admission rates per 100 000 inhabitants were calculated at the regional level and summarized via a Bayesian multilevel meta-analysis. Data were retrieved until April 21st, 2020. Results The highest cumulative mortality rates per 100 000 inhabitants were observed in northern Italy, particularly in Lombardia (85.3, 95% credibility intervals [CI] 75.7–94.7). The difference in the mortality rates between northern and southern Italy increased over time, reaching a difference of 67.72 (95% CI = 66–67) cases on April 2nd. Conclusions Northern Italy showed higher and increasing mortality rates during the first three months of the epidemic. The uncontrolled virus circulation preceding the infection spreading in southern Italy had a considerable impact on system burnout. This experience demonstrates that preparedness against the pandemic is of crucial importance to contain its disruptive effects.

Pattern and mechanism of airway response to hypocapnia in normal subjects

1979 ◽  
Vol 47 (1) ◽  
pp. 8-12 ◽  
Author(s):  
C. F. O'Cain ◽  
M. J. Hensley ◽  
E. R. McFadden ◽  
R. H. Ingram
Keyword(s):  
Vital Capacity ◽  
Normal Subjects ◽  
Oxygen Mixture ◽  
Flow Volume ◽  
Mixture Density ◽  
Lung Capacity ◽  
Airway Constriction ◽  
Maximal Expiratory Flow ◽  
Airway Response ◽  
Expiratory Flow

We examined the bronchoconstriction produced by airway hypocapnia in normal subjects. Maximal expiratory flow at 25% vital capacity on partial expiratory flow-volume (PEFV) curves fell during hypocapnia both on air and on an 80% helium- 20% oxygen mixture. Density dependence also fell, suggesting predominantly small airway constriction. The changes seen on PEFV curves were not found on maximal expiratory flow-volume curves, indicating the inhalation to total lung capacity substantially reversed the constriction. Pretreatment with a beta-sympathomimetic agent blocked the response, whereas atropine pretreatment did not, suggesting that hypocapnia affects airway smooth muscle directly, not via cholinergic efferents.

scholarly journals THE LUNG VOLUME IN HEART DISEASE

1923 ◽  
Vol 38 (4) ◽  
pp. 445-476 ◽  
Author(s):  
Carl A. L. Binger
Keyword(s):  
Heart Disease ◽  
Lung Volume ◽  
Vital Capacity ◽  
Lung Volumes ◽  
Total Lung Volume ◽  
Surface Areas ◽  
Normal Individuals ◽  
The Absolute ◽  
Total Capacity ◽  
Residual Air

The lung volumes in a group of individuals suffering from chronic cardiac disease have been studied by a method which is applicable to patients suffering from dyspnea. In a number of instances the same patients were investigated during various stages of decompensation and compensation. The values found have been compared with those determined in a group of normal subjects. Lung volumes have been considered from three points of view: (1) relative lung volumes or subdivisions of total lung volume expressed as percentage of total lung volume; (2) the absolute lung volumes of patients with heart disease have been compared with lung volumes calculated for normal individuals having similar surface areas or chest measurements; and (3) in individual cases absolute lung volumes have been measured in various stages of compensation and decompensation. (1) In patients with heart disease it has been observed that the vital capacity forms a portion of the total lung volume relatively smaller than in normal individuals, and that the mid-capacity and residual air form relatively larger portions. When the patient progresses from the compensated to the decompensated state these changes become more pronounced. (2) When the absolute lung volumes determined for patients are compared with volumes of the same sort, as calculated for normal individuals of the same surface areas and chest measurements, the following differences are found. The vital capacities are always smaller in the patients and the volumes of residual air are always larger. There is a tendency for middle capacity and total capacity to be smaller, though, when the patients are in a compensated state, these volumes may approximate normal. (3) When decompensation occurs the absolute lung volumes undergo changes as follows: (a) vital capacity, mid-capacity, and total capacity decrease in volume; and (b) the residual air may either increase or decrease according to the severity of the state of decompensation. The significance of these changes has been discussed and an explanation offered for the occurrence of a residual air of normal volume in patients with heart disease. It results from a combination of two tendencies working in opposite directions: one to increase the residual air—stiffness of the lungs (Lungenstarre); the other to decrease it—distended capillaries (Lungenschwellung), edema, round cell infiltration.

Dynamic mechanisms determine functional residual capacity in mice, Mus musculus

1979 ◽  
Vol 46 (5) ◽  
pp. 867-871 ◽  
Author(s):  
A. Vinegar ◽  
E. E. Sinnett ◽  
D. E. Leith
Keyword(s):  
Tidal Volume ◽  
Functional Residual Capacity ◽  
Flow Volume ◽  
Linear Portion ◽  
Volume Curve ◽  
Flow Volume Curve ◽  
Residual Capacity ◽  
Expiratory Flow ◽  
The Difference ◽  
Pentobarbital Sodium Anesthesia

Awake mice (22.6--32.6 g) were anesthetized intravenously during head-out body plethysmography. One minute after pentobarbital sodium anesthesia, tidal volume had fallen from 0.28 +/- 0.04 to 0.14 +/- 0.02 ml and frequency from 181 +/- 20 to 142 +/- 8. Functional residual capacity (FRC) decreased by 0.10 +/- 0.02 ml. Expiratory flow-volume curves were linear, highly repeatable, and submaximal over substantial portions of expiration in awake and anesthetized mice; and expiration was interrupted at substantial flows that abruptly fell to and crossed zero as inspiration interrupted relaxed expiration. FRC is maintained at a higher level in awake mice due to a higher tidal volume and frequency coupled with expiratory braking (persistent inspiratory muscle activity or increased glottal resistance). In anesthetized mice, the absence of braking, coupled with reductions in tidal volume and frequency and a prolonged expiratory period, leads to FRCs that approach relaxation volume (Vr). An equation in derived to express the difference between FRC and Vr in terms of the portion of tidal volume expired without braking, the slope of the linear portion of the expiratory flow-volume curve expressed as V/V, the time fraction of one respiratory cycle spent in unbraked expiration, and respiratory frequency.

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