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Lung Function Tests

Lung Function Tests

Summary of PFT interpretation
Obstructive vs. restrictive disease

Spirometry

Performing spirometry
Summary of interpretation
FEV₁

Expired volume in 1 sec
80-120%
predicted
FVC

Forced vital capacity
80-120%
predicted
FEV₁:FVC Ratio
>0.70
Post-Bronchodilator Reversibility

12% or >200mL increase in FEV1 / FVC

Graphs

Volume-Time Graphs

Deep breath out
Flow-Volume Loops

Deep breath out then in

Lung Volumes

Summary of Lung Volumes
Total Lung Capacity (TLC)

80-120% predicted
80-120%
predicted
Residual Volume (RV)
Functional Residual Capacity (FRC)

Other Tests

DLCO
60-120%
predicted
Bronchial Challenge

Using histamine or methacholine

Volume-Time Graphs

On this page:

Obstructive & Restrictive Patterns

Overview

The volume-time graph is a graphical representation of spirometry results.

Obstructive & Restrictive Patterns

Poor Readings

Last updated on November 15th, 2017

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Chandra Selvi E, Rao KK. Should the Functional Residual Capacity be Ignored?. Journal of clinical and diagnostic research: JCDR. 2013 Jan;7(1):43. D'Urzo AD, Tamari I, Bouchard J, Jhirad R, Jugovic P. New spirometry interpretation algorithm. Canadian Family Physician. 2011 Oct 1;57(10):1148-52. Johnson JD, Theurer WM. A stepwise approach to the interpretation of pulmonary function tests. American Family Physician. 2014 March 1; 89(5): 359-366. Pellegrino R, Viegi G, Brusasco V, Crapo RO, Burgos F, Casaburi RE, Coates A, Van Der Grinten CP, Gustafsson P, Hankinson J, Jensen R. Interpretative strategies for lung function tests. European Respiratory Journal. 2005 Nov 1;26(5):948-68.

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