Core Pulmonary Concepts. Lung volumes and capacities

Core Pulmonary Concepts

Lung volumes and capacities

Pulmonary Function

Lung volumes Tidal volume (Vt)

Inspiratory reserve volume (IRV)

Expiratory Reserve volume (ERV)

Residual volume (RV)

Lung capacities Vital capacity (VC)

Inspiratory capacity (IC)

Functional Residual Capacity

Total lung capacity (TLC)

Spirometery

Core measurements FVC

Forced vital capacity: maximum volume that can be exhaled forcefully (aka VC)

FEV1: forced expiratory volume 1 second

maximum volume exhaled in the first second of the test

Core measurements Peak expiratory flow rate (PEFR): Maximum flow rate during a FVC

maneuver; varies with sex, age, height, etc.

FEF25-75% : forced expiratory flow, 25-75%-the average flow rate dudring the mid portion of the test

Flow-volume loop

Diagnostic terms Obstructive

Flow-limited defect Difficulty getting the

air out of the lungs The following values

are all diminished: FVC, PEFR, FEV1,

FEF25-75

Restrictive Volume-limited

defect Difficulty getting the

air into the lung The following values

are diminished: FVC, FE 1, TLC Flows are normal

Lung disease via PFT Flow-limited

All flows are diminished

PEFR FEF25-75

Hallmark: air trapping

Volume-limited Flows are normal to

super-normal (elasticity of lungs is increased)

Volumes are small

Hallmark: “tiny” lungs

Key values

FEV1--gold standard All research in lung function reports this

value

FEF25-75% -another standard Reflects, anatomically, the small to medium

size airways (bronchi)