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Pulmonary Function Testing

The lungs, heart and blood vessels work together to ensure that oxygen and carbon dioxide get to where they need to go in the body. As part of the same system, heart and blood vessel conditions can affect—and be affected by—the condition of the lungs. Because of this, pulmonary (lung) function tests can be useful in diagnosis and monitoring, and in planning for cardiovascular surgery.

Temple offers a number of procedures to determine how well the lungs and breathing muscles are working—and whether they’re functioning well in tandem with the heart and blood vessels to circulate oxygen throughout the body. These tests are carried out by the Pulmonary Function Laboratory at Temple Lung Center, working closely with Temple’s cardiovascular specialists.

Tests may measure:

  • Lung volumes (amount of air breathed in and out, or amount held in the lungs after exhalation)
  • Lung capacity (the amount of air the lungs can hold)
  • Airway resistance (how easily air flows through, to and from the lungs)
  • Respiratory muscle strength (performance of muscles like the diaphragm and costal muscles that help the lungs expand and contract—this is usually measured by proxy, using air flow in the lungs)
  • Diffusing capacity (how well the lungs perform gas exchange, the uptake and release of oxygen and CO2)

Taken together, these measurements can pinpoint breathing issues and help to diagnose their causes. Testing may include:

  • Spirometry: A breathing tube connected to a machine is used to measure the amount, speed and flow of air a patient inhales and exhales. A spirometer can also be used to measure lung capacity through a technique called gas dilution, in which the patient breathes in a solution containing a certain amount of helium gas, and concentration of the gas allows us to calculate the volume of the lung and airway space.
  • Body plethysmography: Used to measure a patient’s lung volumes and airway resistance. Plethysmography involves sitting in an airtight box in which air pressure can be measured very precisely; the patient briefly attempts to suck in air through a closed mouthpiece, opening the lungs and allowing the machine to calculate lung volume via changes in air pressure. 
  • Forced oscillation technique: Another method in which the patient breathes through a tube attached to a machine. The machine uses a series of small changes in air pressure to calculate the space, pressure, and air flow in the lungs.
  • Bronchochallenge testing: Often used to diagnose asthma. The patient is given medications that constrict the airways, and the amount of constriction is measured by a spirometer (patients with asthma respond more strongly). They may also then receive a medication that relaxes the airway; this can help distinguish asthma from chronic obstructive pulmonary disease (COPD), which isn’t affected by relaxant medication.
  • Carbon monoxide diffusion test (DLCO): The patient breathes in a certain (nondangerous) amount of carbon monoxide, and a machine calculates how much of the gas was taken up by the lungs. This helps determine the lungs’ ability to perform their ultimate function, gas diffusion—and therefore measures the severity of conditions like bronchitis, emphysema, and COPD.
  • Arterial puncture: A blood sample is taken from an artery (usually in the wrist) to look at the concentration of different gases in the blood; like DLCO, this provides information on gas exchange in the lungs.
  • Six-minute walk tests: Testing a patient’s exercise capacity by measuring how far they can walk on a flat surface in the course of 6 minutes.
  • Oxygen titration studies: Used for patients who are on supplemental oxygen. A pulse oximeter (a device usually worn on the finger) is used to determine how much oxygen levels drop during exercise, and how much oxygen is needed to keep them stable.
  • Cardio-pulmonary stress tests: Various measures of heart and lung function—such as oxygen use, blood pressure, blood oxygen levels, and heartbeat—are measured while a patient exercises, often on a stationary bike.
  • Bronchoscopy: A physician feeds a thin, flexible viewing instrument called a bronchoscope in through the mouth or nose to examine a patient’s airways; tissue samples of the lungs or airways may also be taken.
  • Thoracentesis: A needle injected through the chest wall is used to remove fluid that has built up in the space around the lung lining (the pleural space), or to sample the fluid for analysis.

Why Temple?

Temple’s pulmonary and cardiovascular physicians work in close collaboration—with one another and with patients—to monitor the body’s whole circulatory system and ensure patients receive appropriate, comprehensive treatment.