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Lung Diseases

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The goals of testing are to diagnose lung diseases, determine their causes where possible, and evaluate their severity. Many health practitioners will order blood gases to evaluate oxygen and carbon dioxide levels, lung or pulmonary function tests (PFTs) to help diagnose and monitor lung function, and chest x-rays and or CT (computed tomography) scans to look at lung structure. Other testing is performed to help diagnose specific conditions.

Laboratory tests

Some tests may be performed to help determine a person's health status and how well the lungs are working. Examples include:

Additional tests may be performed to help diagnose certain lung conditions:

Lung function tests (pulmonary function tests, PFT)
A few of the more common tests are listed below. For more complete information, visit the web site for Johns Hopkins Medicine: Pulmonary Function Laboratory.

  • Spirometry – measures the amount and rate of air exhalation as a person blows out through a tube; it is performed to evaluate narrowed or obstructed airways.
  • Oximetry – measures the oxygen saturation of the blood using a small device placed on a person's finger
  • Exercise stress test – monitors lung function on a person while they are on a stationary bike or treadmill
  • Air flow with a peak flow meter – measures the rate of exhalation; it can be used at home by people with asthma to help monitor their condition.
  • Lung volume – the quantity of air a person takes into their lungs and how much is left in the lungs after exhalation; it helps evaluate the elasticity of the lungs, the movement of the rib cage, and the strength of the muscles associated with respiration.
  • Diffusing capacity measurement – assesses the transfer of oxygen from the lung air sacs to the bloodstream by evaluating how much carbon monoxide is absorbed when a small quantity is inhaled (not enough to harm)

Imaging studies

  • Chest x-ray – to look at lung structure and chest cavity
  • CT (computed tomography) scan – a more detailed evaluation of lung structure
  • MRI (Magnetic resonance imaging) – detailed pictures of organs and vessels in the chest
  • Ultrasound – used to detect fluid between the pleural membranes
  • Nuclear lung scanning – used to help detect pulmonary embolism and, rarely, to evaluate the effectiveness of lung cancer treatment
  • Positron emission tomography (PET) scans – used to help diagnose lung cancer

For more on these, see the website.

Other tests

  • Electrocardiogram (EKG, ECG) – to look at heart rhythm, to determine if heart disease may be affecting breathing
  • Sleep studies – usually performed at special sleep centers to help determine whether a person is breathing normally during sleep

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