PULMONARY FUNCTION TEST

SUMMARY

1. FEV₁, FVC & TLC < 80% or RV > 120% are abnormal.

2. TLC is decreased in restrictive lung disease. Extra-thoracic (obesity, kyphosis) vs. intra-thoracic causes (ILD, parenchymal disease).

3. Expiratory flow rate (ratio of forced expiratory volume in 1 sec to FVC; FEV₁/FVC) < 0.7 (70%) is diagnostic of obstructive lung disease. Causes: asthma, COPD, bornchiectasis, cystic fibrosis. Significant bronchodilator reversibility is defined by a 12% and greater than 200 mL increase in either FEV₁ or FVC, or both.

Reference(s)

Wilkinson, I. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].