lungfunktion

Lungfunktion, or lung function, describes the capacity of the respiratory system to ventilate the lungs, move air to and from the alveoli, and exchange gases with the blood. It encompasses lung volumes, airflow, and gas transfer efficiency. Clinically, lungfunktion is assessed with standardized tests that quantify how much air the lungs can hold, how quickly air can be moved out, and how effectively oxygen and carbon dioxide are exchanged.

The primary measurement is spirometry, which yields forced vital capacity (FVC) and the amount of air expelled in the first second (FEV1), along with the FEV1/FVC ratio. Peak expiratory flow (PEF) can be useful for home monitoring. Lung volumes such as total lung capacity (TLC), functional residual capacity (FRC), and residual volume (RV) are measured by body plethysmography or gas-dilution methods. Gas exchange is evaluated with the diffusing capacity of the lungs for carbon monoxide (DLCO), which reflects the transfer of gas across the alveolar–capillary membrane.

Normal values depend on age, sex, height, and ethnicity, and results are usually expressed as absolute values and as percent predicted. Patterns in the results help characterize disease: obstructive patterns show reduced FEV1 and FEV1/FVC, while restrictive patterns show reduced TLC or vital capacity.

Applications include diagnosis and monitoring of asthma, chronic obstructive pulmonary disease (COPD), and interstitial or other restrictive lung diseases; preoperative risk assessment; and evaluation of treatment response. Tests require adequate patient effort and technique, and results are influenced by equipment calibration and reference standards. Guidelines from bodies such as ATS/ERS standardize testing and interpretation.