Core Pulmonary Concepts Lung volumes and capacities Pulmonary

Core Pulmonary Concepts

Lung volumes and capacities

Pulmonary Function

Lung volumes n Tidal volume (Vt) n Inspiratory reserve volume (IRV) n Expiratory Reserve volume (ERV) n Residual volume (RV)

Lung capacities n Vital capacity (VC) n Inspiratory capacity (IC) n Functional Residual Capacity n Total lung capacity (TLC)

Spirometery

Core measurements n FVC n Forced vital capacity: maximum volume that can be exhaled forcefully (aka VC) FEV 1: forced expiratory volume 1 second maximum volume exhaled in the first second of the test

Core measurements n n n Peak expiratory flow rate (PEFR): Maximum flow rate during a FVC maneuver; varies with sex, age, height, etc. FEF 25 -75% : forced expiratory flow, 2575%-the average flow rate dudring the mid portion of the test

Flow-volume loop

Diagnostic terms n Obstructive n n n Flow-limited defect Difficulty getting the air out of the lungs The following values are all diminished: n FVC, PEFR, FEV 1, FEF 25 -75 n Restrictive n n n Volume-limited defect Difficulty getting the air into the lung The following values are diminished: n n FVC, FE 1, TLC Flows are normal

Lung disease via PFT n Flow-limited n n n All flows are diminished PEFR FEF 25 -75 n Volume-limited n n n Hallmark: air trapping n Flows are normal to super-normal (elasticity of lungs is increased) Volumes are small Hallmark: “tiny” lungs

Key values n FEV 1 --gold standard n n All research in lung function reports this value FEF 25 -75% -another standard n Reflects, anatomically, the small to medium size airways (bronchi)