Chest
Volume 76, Issue 6, December 1979, Pages 622-628
Journal home page for Chest

Clinical Investigations
Determination of Bronchodilation in the Clinical Pulmonary Function Laboratory: Role of Changes in Static Lung Volumes

https://doi.org/10.1378/chest.76.6.622Get rights and content

Improved airway resistance following bronchodilator inhalation is not always accompanied by improvement in forced expiratory flow. We studied 241 patients with airways obstruction to learn whether changes in static lung volumes (vital capacity and function residual capacity measured by body plethysmography [FRCB]) would reveal bronchodilation not demonstrated by expiratory flow rates (the ratio of forced vital capacity at one second to the total forced vital capacity [FEV1/FVC]), and the forced expiratory flow for the midportion of the forced vital capacity (FEF25–75%). A significant fall in Raw occurred in 129 patients, 46 of whom had a significant increase in vital capacity (mean of + 465 ml ± 43, P < 0.001) and a fall in FRCB (mean of −763 ml ± 78 P < 0.001) with no change in FEV1/FVC% or FEF25–75%. We interpret these data to indicate that improvement in static lung volumes can reflect bronchodilation in the absence of improved expiratory flow.

Section snippets

MATERIALS AND METHODS

The results of the pulmonary function studies of all patients referred to the Pulmonary Physiology Laboratory of the La Jolla Veterans Administration Hospital for evaluation of bronchodilator response to inhaled isoproterenol over a one-year period were analyzed retrospectively. All patients were evaluated clinically prior to testing on the basis of an interview and the response to a standard questionnaire modified after the British Medical Research Council Pulmonary Questionnaire. Standard

Patterns of Response

Two hundred forty-one patients underwent bronchodilator testing during a 12-month period. One hundred twenty-nine of the patients (54 percent) had no improvement in either static lung volumes or dynamic flow rates after administration’ of isoproterenol (Table 1). Of the 112 patients (46 percent of those studied) who did respond, 46 (41 percent of all responders and 19 percent of all patients tested) showed an increase in VC and fall in FRCB without a change in flow rates (isolated volume

DISCUSSION

These data indicate that patients with reversible obstructive airways disease can be identified in the clinical pulmonary function laboratory by selective improvement in static lung volumes after administration of isoproterenol. On the basis of changes in static lung volume parameters (VC and FRCB) and dynamic lung function parameters (FEV1/FVC% or FEF25–75%,), the patients studied could be separated into three patterns of response: isolated volume (increased VC and decreased FRCB following

REFERENCES (17)

  • AJ Woolcock et al.

    Lung volumes in exacerbations of asthma

    Am J Med

    (1966)
  • AB DuBois et al.

    A rapid plethysmographic method for measuring thoracic gas volume: A comparison with a nitrogen washout method for measuring functional residual capacity in normal subjects

    J Clin Invest

    (1956)
  • AB DuBois et al.

    Jr: A new method for measuring airway resistance in man using a body plethysmograph: Values in normal subjects and in patients with respiratory disease

    J Clin Invest

    (1956)
  • RE Nye

    Jr: Closed circuit method for measuring uneven ventilation

    J Appl Physiol

    (1961)
  • A Dawson

    Reproducibility of spirometric measurements in normal subjects

    Am Rev Resp Dis

    (1966)
  • JF Morris et al.

    Normal values for the ratio of one second forced expiratory volume to forced vital capacity

    Am Rev Respir Dis

    (1973)
  • LloydTC et al.

    Evaluation of methods used in detecting changes in airways resistance in man

    Am Rev Respir Dis

    (1963)
  • AJ Woolcock et al.

    Lung volume changes in asthmatics measured concurrently by two methods

    Am Rev Respir Dis

    (1971)
There are more references available in the full text version of this article.

Cited by (0)

Manuscript received January 12; revision accepted March 20.

View full text