Lung Function Tests Normal and abnormal Prof. J. Hanacek, MD, PhD

Parameters of spirographic curve

Lung volume changes under physiological and pathological conditions

Flow-volume characteristics in different pathological processes

VC-Vital Capacity - The amount of air that can be forcibly exhaled from your lung after a full inhalation. FVC-Forced Vital Capacity - The amount of air which can be exhaled from the lungs by maximal effort after taking the deepest breath possible. FEV1-Forced Expiratory Volume in One Second - The amount of air which can be forcibly exhaled from the lungs in the first second of a forced exhalation. FEV1/FVC = FEV1-Percent (FEV1%) - The ratio of FEV1 to FVC and tells the clinician what percentage of the total amount of air is exhaled from the lungs during the first second of forced exhalation. Common Terminology of Spirometry Tests Critical in Diagnosing COPD

PEFR- Peak Expiratory Flow Rate- Measures if treatment is effective in improving airway diseases such as COPD. FEF-Forced Expiratory Flow - A measure of how much air can be exhaled from the lungs. It is an indicator of large airway obstruction. MVV-Maximal Voluntary Ventilation - A value determined by having the patient inhale and exhale as rapidly and fully as possible in 12 seconds. The results reflect the status of the muscles used for breathing, how stiff the lungs are and if there is any resistance in the airways when breathing. This test tells surgeons how strong a patient's lungs are prior to surgery. If patients demonstrate poor performance on this test, it suggests to the doctor that respiratory complications may occur after surgery.

GOLD Spirometric Criteria for COPD Severity I. Mild COPD: FEV1/FVC < 0.7 FEV1 >/= 80% predicted The patient is probably unaware that lung function is starting to decline II. Moderate COPD: FEV1/FVC < % </= FEV1 < 80% predicted Symptoms during this stage progress, with shortness of breath developing upon exertion III. Severe COPD: FEV1/FVC < % </= FEV1 < 50% predicted Shortness of breath becomes worse at this stage and COPD exacerbations are common IV. Very Severe COPD: FEV1/FVC < 0.7 FEV1 < 30% predicted or FEV1< 50% predicted with chronic respiratory failure Quality of life at this stage is gravely impaired. COPD exacerbations can be life threatening