Gas exchange 

Pulmonary Function Tests

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• Assess presence and severity of diseases in large and small airways
• Spirometer measures the volume of air moving in and out of the lungs and then calculates the lung capacities; An example of its use is for patients with asthma; as their bronchoconstriction worsens, they exhale less air-Reported as decreased forced expiratory volume
• Used to distinguish between obstructive and restrictive pulmonary diseases
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• Patients with obstructive lung disease-air trapping increases, such as cystic fibrosis or COPD, more air remains in their lungs-reflected as an increase in reserve volume
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• Obstructive lung diseases impair patients’ ability to get air out of the lungs