PFT handout Flashcards
Peak Expiratory Flow Rate (PEFR).
The first landmark reached is the PEFR. The first blast of air exhaled from the patient reaches this flow rate almost immediately. The flow rate then quickly slows as more air is exhaled. This landmark is very important in judging if the patient is giving maximal effort, overall quality of the test, strength of expiratory muscles, and the condition of the large airways, such as the trachea and main bronchi.
Forced Expiratory Volume after 0.5 seconds (FEV0.5).
The FEV0.5 indicates the amount of air exhaled with maximum effort in half a second.
Forced Expiratory Volume after 1 second (FEV1).
The FEV1 indicates the amount of air exhaled with maximum effort in the first second. The FEV1 is another very important landmark in assessing the overall status of the patient and quality of the test. This test result is also important in pre- and post-bronchodilator tests in determining the effects of bronchodilators on the airways.
Forced Expiratory Volume after 3 seconds (FEV3).
The FEV3 indicates the amount of air exhaled with maximum effort in the first three seconds.
Forced Expiratory Volume after 6 seconds (FEV6).
The FEV6 indicates the amount of air exhaled with maximum effort in the first six seconds. This parameter is primarily used to ensure expiratory efforts meet or exceed 6 seconds
Forced Vital Capacity (FVC).
Another important result of a Flow Volume Loop is the FVC. Many of the other results depend on this number. The FVC is the total volume of air exhaled with maximal effort.
Forced Expiratory Flow at 25% of FVC (FEF25%).
The FEF25% is the flow rate at the 25% point of the total volume (FVC) exhaled. Assuming maximal effort this flow rate is still indicative of the condition of fairly large to medium size bronchi. This landmark is used in calculations with the FEF75% to give FEF25-75%, the middle half of the FVC, which many physicians look at as not being dependent on patient effort and an indicator for obstruction in the small airways. This value is very dependent on the total volume exhaled (FVC) and tends to be highly variable from test to test.
Forced Expiratory Flow at 50% of FVC (FEF50%).
The FEF50% is the flow rate at the 50% point of the total volume (FVC) exhaled. This landmark is at the midpoint of the FVC and indicates the status of medium to small airways, it’s sometimes looked at instead of the FEF25-75%.
Forced Expiratory Flow at 75% of FVC (FEF75%).
The FEF75% is the flow rate at the 75% point of the total volume (FVC) exhaled. This landmark indicates the status of small airways and is used in the FEF25-75% calculation. The damage done by most chronic pulmonary diseases show up in the smallest airways first and early indications of this damage begin to appear toward the end of the expiratory part of the Flow Volume Loop.
Forced Inspiratory Flow at 25% of FVC (FIF25%).
The FIF25% is the flow rate at the 25% point on the total volume inhaled. The inspiratory flow rates are relatively unimportant in assessing the asthmatic. Abnormalities here are indicators of upper airway obstructions. Areas of the mouth, upper and lower pharynx (back of the throat), larynx (voice box), and vocal-cords impact the inspiratory flow rates.
Peak Inspiratory Flow Rate (PIFR).
The fastest flow rate achieved during inspiration.
Forced Inspiratory Flow at 50% of FVC (FIF50%).
The FIF50% is the flow rate at the 50% point on the total volume inhaled.
Forced Inspiratory Flow at 75% of FVC (FIF75%).
The FIF75% is the flow rate at the 75% point on the total volume inhaled.
FEV1/FVC%, and FEV3/FVC% -
These are ratios calculated by dividing the Forced Expiratory Volume results by the Forced Vital Capacity and expressed as a percentage of the FVC.
Forced Expiratory Time (FET)
The time it takes to exhale as much air as possible. To obtain reliable FVC values, the expiratory effort should be continued for at least 6 seconds. The FET should never be less than 6 seconds unless the patient is severely restricted.
