lungvolym

Lungvolym, or lung volumes, refers to the amount of air contained in the lungs at various points in the breathing cycle. The concept is used to describe the size of the lungs and how much air they can hold under resting conditions and during effort. Lungvolym are typically described as static volumes, which do not depend on the rate of breathing, and as derived capacities that summarize multiple volumes.

Static lung volumes include total lung capacity (TLC), which is the maximum amount of air the lungs can contain after a deep breath; vital capacity (VC), the maximum amount of air that can be forcibly exhaled after a full inhalation; tidal volume (VT), the amount of air moved in or out with a normal breath; inspiratory reserve volume (IRV) and expiratory reserve volume (ERV), the additional amounts that can be inhaled or exhaled beyond the tidal volume. Residual volume (RV) is the air remaining in the lungs after a maximal expiration. Functional residual capacity (FRC) is the sum of ERV and RV, representing the air remaining in the lungs at the end of a normal exhalation.

Measurement and interpretation can involve different techniques. Spirometry can assess VT, VC, and related flows, but TLC and RV require body plethysmography or gas-dilution methods. Normal values vary with age, sex, height, posture, and ethnicity, so interpretation is usually relative to reference ranges for the individual.

Clinical relevance lies in distinguishing restrictive from obstructive patterns. In restrictive conditions, TLC and FRC tend to decrease, reflecting reduced lung size. In obstructive diseases, RV and sometimes FRC may be increased due to air trapping, while VC and VT can be reduced. Lungvolym are foundational elements of pulmonary function testing and preoperative assessment.