Physiology of Breathing - Page 11 of 15

Module 4: Physiology of the Respiratory System - Curves Showing Mixed Obstructive And Restrictive Abnormalities.

Curves Showing Mixed Obstructive And Restrictive Abnormalities:

Combined or mixed patterns of lung function abnormality can co-exist.
This may result from co-existence of pathologies (e.g. asbestosis in a smoker); or
May occur in severe obstructive airways disease alone because of hyperinflation; or
May result from destructive disease that affects both lung parenchyma and airways.

Obstruction with a reduced FVC: emphysema.

Destruction of alveolar walls leads to a loss of lung elasticity.
During exhalation this loss of elasticity and dynamic airways compression leads to early closure of smaller conducting airways.
This result in air trapping in the lung, causing hyperinflation and an increased RV.
TLC may increase but the net effect is still a reduced FVC.

Obstruction with a reduced FVC: tuberculosis.

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Postgraduate Diploma in Occupational Health (DOH) - Modules 3 � 5: Occupational Medicine & Toxicology by Prof Rodney Ehrlich & Prof Mohamed Jeebhay is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
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