Spirrometry

Spirrometry, commonly referred to as spirometry, is a standard pulmonary function test that measures how much air a person can exhale forcefully, how quickly the air is exhaled, and how much air remains in the lungs after a maximal exhalation. The test provides quantitative indices and graphs, including a volume-time curve and a flow-volume loop, used to assess ventilatory function.

During the examination, the patient breathes through a mouthpiece connected to a spirometer after a maximal inhalation. The patient then performs a rapid, forceful exhale to full expiration, often repeated to achieve reproducible results. Proper technique and patient cooperation are essential; tests are performed under calibration and quality-control procedures to ensure accuracy. Spirometry cannot measure all aspects of lung function and is typically complemented by other tests when necessary.

Key measures include the forced expiratory volume in one second (FEV1), the forced vital capacity (FVC), and their ratio FEV1/FVC. Additional indices may include peak expiratory flow (PEF) and mid-expiratory flow (FEF25-75). Results are usually reported as absolute values and as a percentage of predicted values adjusted for age, sex, height, and ethnicity.

Indications include evaluation of suspected obstructive diseases such as asthma or COPD, assessment of restrictive patterns, and monitoring of response to therapy or disease progression. It is also used in preoperative risk assessment and occupational health.

Limitations include dependence on patient effort, and variability due to technique or equipment; interpretation should consider quality criteria and be integrated with clinical findings.