PULMONARY MECHANICS IN ASTHMA AND CYSTIC FIBROSIS

Maximum expiratory flow rates on flow-volume curves are often decreased below normal limits in children with asthma or cystic fibrosis who are clinically well and whose standard spirometric tests are within normal limits. In particular, maximum flow rates at small lung volumes (25% of vital capacity) are decreased. Maximum expiratory flow-volume (MEFV) curves provide a sensitive and quantitative assessment of small airway obstruction in these and other obstructive lung conditions.

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OBSTRUCTIVE DISEASE OF THE AIRWAYS IN CYSTIC FIBROSIS

PEDIATRICS ◽

10.1542/peds.41.3.560 ◽

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.

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Pulmonary mechanics during exercise in subjects with chronic airflow obstruction

Journal of Applied Physiology ◽

10.1152/jappl.1980.49.3.511 ◽

1980 ◽

Vol 49 (3) ◽

pp. 511-515 ◽

Cited By ~ 163

Author(s):

D. G. Stubbing ◽

L. D. Pengelly ◽

J. L. Morse ◽

N. L. Jones

Keyword(s):

Tidal Flow ◽

Airflow Obstruction ◽

Maximum Flow ◽

Transpulmonary Pressure ◽

Pulmonary Mechanics ◽

Flow Volume ◽

Tidal Breathing ◽

Flow Rates ◽

Control Value ◽

Expiratory Flow

A body plethysmograph was used to measure pulmonary mechanics in six subjects with chronic airflow obstruction during steady states at rest and during exercise at 200 and 400 kpm . min-1. The mean forced expired volume in 1 s was 1.32 liters (39.2% predicted). The flow rates during tidal breathing reached the maximum expiratory flow-volume (MEFV) curve in all but one subject, and on exercise they all reached the MEFV curve. Total lung capacity did not change significantly, but functional residual capacity increased to 104% of the control value (P less than 0.05) and residual volume increased to 113.3% of the control value (P less than 0.02). The MEFV curves did not change and tidal flow rates in excess of th MEFV curve were not seen. Dynamic compliance fell with increasing exercise to 52.8% (P less than 0.01) and static expiratory pulmonary compliance to 90.2% of the control value. Transpulmonary pressures during tidal breathing when expiratory flow reached the MEFV curve increased to progressively higher values as the work load increased. At low work loads there were several subjects with negative transpulmonary pressure when maximum flow rates were present. In patients with chronic airflow obstruction, little change occurs during exercise in pulmonary mechanics; the tidal flow patterns are dominated by the expired flow-volume curve, which is not changed by exercise; maximum flow occurs in some patients when transpulmonary pressure is still negative.

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

Journal of Applied Physiology ◽

10.1152/jappl.1981.50.3.650 ◽

1981 ◽

Vol 50 (3) ◽

pp. 650-657 ◽

Cited By ~ 22

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.

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Predicting arterial oxygen tension from maximum expiratory flow volume curves in cystic fibrosis

Pediatric Pulmonology ◽

10.1002/ppul.1950060108 ◽

1989 ◽

Vol 6 (1) ◽

pp. 27-30 ◽

Cited By ~ 1

Author(s):

Arlene A. Stecenko ◽

Linda Postotnik ◽

Ronald G. Thomas

Keyword(s):

Cystic Fibrosis ◽

Oxygen Tension ◽

Arterial Oxygen Tension ◽

Arterial Oxygen ◽

Flow Volume ◽

Maximum Expiratory Flow ◽

Expiratory Flow

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Volume Adjustment of Maximal Expiratory Flow Rates of Flow-Volume Loops

CHEST Journal ◽

10.1378/chest.102.5.1636-c ◽

1992 ◽

Vol 102 (5) ◽

pp. 1636-1637

Author(s):

Sema Umut ◽

Bilun Gemicioğlu ◽

Nurhayat Yildirim

Keyword(s):

Flow Volume ◽

Flow Rates ◽

Maximal Expiratory Flow ◽

Expiratory Flow ◽

Expiratory Flow Rates

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Re-evaluation of Mist Therapy in Children with Cystic Fibrosis Using Maximum Expiratory Flow-volume Curves

Pediatric Research ◽

10.1203/00006450-197009000-00174 ◽

1970 ◽

Vol 4 (5) ◽

pp. 478-478

Author(s):

Etsuro K Motoyama ◽

Lewis E Gibson ◽

Charlene J Zigas ◽

Charles D Cook

Keyword(s):

Cystic Fibrosis ◽

Flow Volume ◽

Maximum Expiratory Flow ◽

Expiratory Flow

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Inhalation challenge tests in asthma: an assessment of spirometry, maximum expiratory flow rates and plethysmography in measuring the responses

Clinical & Experimental Allergy ◽

10.1111/j.1365-2222.1974.tb01398.x ◽

1974 ◽

Vol 4 (4) ◽

pp. 371-378 ◽

Cited By ~ 7

Author(s):

S. P. HAYDU ◽

D. W. EMPEY ◽

D. T. D. HUGHES

Keyword(s):

Flow Rates ◽

Maximum Expiratory Flow ◽

Challenge Tests ◽

Inhalation Challenge ◽

Expiratory Flow ◽

Expiratory Flow Rates

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Correlations of maximum expiratory flow with small airway dimensions and pathology

Journal of Applied Physiology ◽

10.1152/jappl.1982.52.2.346 ◽

1982 ◽

Vol 52 (2) ◽

pp. 346-351 ◽

Cited By ~ 18

Author(s):

N. Berend ◽

W. M. Thurlbeck

Keyword(s):

Maximum Flow ◽

Transpulmonary Pressure ◽

Small Airway ◽

Flow Volume ◽

Human Lungs ◽

Muscle Hyperplasia ◽

Maximum Expiratory Flow ◽

Expiratory Flow ◽

Inflammation Score ◽

Airway Dimensions

Pressure-volume and maximum expiratory flow-volume curves with air and a He-O2 mixture were performed in 25 excised human lungs. Small airway dimensions were measured, and the degree of various small airway lesions and emphysema was graded. Correlations were then made between the maximum flow (Vmax) at a transpulmonary pressure (PL) of 5 cmH2O and these measurements and scores. Small airway dimensions correlated poorly with Vmax. However, significant correlations were obtained between Vmax and the inflammation score (P less than 0.05), fibrosis score (P less than 0.05), and emphysema grade (P less than 0.01) but not smooth muscle hyperplasia or pigmentation. Neither the increase in flow with He-O2 nor the volume of flow correlated significantly with any small airway measurement or score.

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Randomized Comparison of Two Spacer Devices in Subjects with Reversible Airflow Limitation

Canadian Respiratory Journal ◽

10.1155/1994/707806 ◽

1994 ◽

Vol 1 (4) ◽

pp. 257-260

Author(s):

Fred W Clarke ◽

Leslie L Montgomery ◽

David G Stubbing

Keyword(s):

Cost Savings ◽

Final Analysis ◽

Primary Outcome Measure ◽

Airflow Limitation ◽

Laboratory Population ◽

Flow Rates ◽

Maximum Expiratory Flow ◽

Measure Change ◽

Expiratory Flow ◽

Expiratory Flow Rates

OBJECTIVE: To assess a new spacer device. the ACE. by comparing it with the Aerochamber in subjects with reversible airflow limilation and assessing the change in lung function after inhaled bronchodilator.DESIGN: A randomized single-blind cross-over trial was performed.SETTING: Hospital-based pulmonary function laboratory. POPULATION STUDIED: Thirty subjects with reversible airflow limitation. Mean forced expired volume in Is (FEV1) was 1.37 L. range O.8 to 3.3 L. All subjects had previously shown at least 15% reversibility after inhaled bronchodilator. All inhaled bronchodilators were witheld for 6 h. Subjects were studied on two separate days. Four subjects were excluded from the final analysis because baseline FEV1varied by greater than 10% between the two study days. Maximum expiratory fow rates were used as the primary outcome measure· Change in heart rate was assessed for adverse effects.INTERVENTIONS: The change in maximum expiratory flow rates was assessed 15 mins after two, three and four pulls of inhaled salbutamol delivered via one or the spacer devices. The use of spacer was randomized.RESULTS: Data from 26 subjects were analyzed. Baseline FEV1was similar on the two study days: 1.37±0.13 L (ACE) and 1.38±0.14 L. (Aerochamber). The change in FEV1was similar on both study days. The change in all the maximum expiratory flow rates was similar with both spacer devices. FEV1after four pulls of salbutamol was 1.7±0.16 L. (ACE) and I.71 ±0.16 L (Aerochamber).CONCLUSION: The bronchodilation achieved was similar with both spacers. Because the ACE is cheaper. it may offer cost savings to individuals or institutions.

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