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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
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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)
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
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 Diagnostic terms
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 Lung disease via PFT
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)