What Do Lung Function Tests Show?

Breathing Tests

Spirometry

Spirometry can show whether you have:

• Blockage (obstruction) in your airways. This may be a sign of asthma, COPD (chronic obstructive pulmonary disease), or another obstructive lung condition.
• Smaller than normal lungs (restriction). This may be a sign of heart failure, damage or scarring of the lung tissues, or another restrictive lung condition.

Peak Flow Meter

A peak flow meter shows the fastest rate at which you can blow air out of your lungs. People who have asthma use this device to help track their breathing.

Lung Volume Measurement

This test shows the size of your lungs. Abnormal test results may show that you have lung tissue scarring or a stiff chest wall.

Lung Diffusion Capacity

This test can show a problem with oxygen moving from your lungs into your bloodstream. This may be a sign of loss of lung tissue, emphysema (a type of COPD), or problems with blood flow through the body's arteries.

Tests To Measure Oxygen Level

Pulse oximetry and arterial blood gas tests measure the oxygen level in your blood. These tests show how well your lungs are taking in oxygen and moving it into the bloodstream. A low level of oxygen in the blood may be a sign of a lung or heart condition.