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Chapter 4.6 Pulmonary Function Tests

BOOK TITLE: Understanding Medical Physiology: A Textbook for Medical Students

Author
1. Bijlani R.L.
ISBN
9788180612213
DOI
10.5005/jp/books/10999_36
Edition
3/e
Publishing Year
2004
Pages
8
Author Affiliations
1. All India Institute of Medical Sciences, New Delhi
Chapter keywords
diffusion defect, poor diagnostic value, investigations, mechanical obstacle, airway resistance, nitrogen concentration, ventilator function, anatomical dead space, respiratory tract, pressure gradient, diffusing capacity, physical examination, functional nature, vital capacity, spirometry, intrathoracic pressure

Abstract

This chapter discusses pulmonary function tests, which cannot give the diagnosis because the same degree of defect in ventilation, perfusion or diffusion may occur in a wide variety of diseases. The value of pulmonary function tests lies in giving the functional nature of the disease and its severity. Pulmonary function tests also have a medicolegal value in deciding the amount of compensation in cases where impairment of lung function might have been produced by an occupational hazard. The major aim of the tests of ventilation is to distinguish between restrictive and obstructive diseases. Flow rates during breathing are also indicators of airway resistance. The rate of air flow during breathing can be monitored continuously using a pneumotachograph. The ventilation is normally greater at the bases than at the apices of lungs. Diffusion is the net movement of a fluid from one compartment to another due to concentration difference.

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