Pulmonary Function Tests (PFT) Flashcards
Three main PFT’s
- Spirometry = to identify obstruction
- Lung volume Determination = to identify restriction
- Diffusion Capacity Measurement = to identify a diffusion defect
What is normal PFT measurement relative to predicted values?
values between 80% and 120 %
What are signs of obstruction on spirometry?
Reduced ratio of FEV1 to FVC (normal is 70%)
-“Scooping” of Flow volume loop
FEV1 severity guidelines
mild = 60 -80%
moderate = 40 - 60%
severe =
Reversibility guidelines
-FEV1 increase by 200 cc and 12% with bronchodilator
Hyper-reactivity challenge
- What do you give them?
- Decrease by how much?
- methacholine
- FEV1 decrease by 20 %
Small airway obstruction
- gradually decreasing airflow
- obstruction worsens as lung volume decreases
- –due to decreased tethering of bronchioles at low volumes
Upper airway obstruction
- airflow is fixed
- –even at high lung volumes since large airways don’t depend upon tethering to remain open
Where is the obstruction located if it affects the inspiratory limb?
-extra thoracic
Where is the obstruction located if it affects the expiratory limb?
-Intra thoracic
What tests are used to measure lung volumes?
Helium Dilution
Body Box Plethysmography
Restrictive Lung Disease guidelines
-less than 80% of predicted
Interstitial Lung Disease mnemonic
- Sarcoid
- Hypersensitivity Pneumonitis
- Idiopathic Pulmonary Fibrosis
- Tuberculosis
- Fungal
- Aspiration/Asbestosis
- Connective Tissue Diseases/ (Cancer)
- Eosinophilic granuloma
- Drugs
Three categorical causes of Restrictive Lung Diseases
- Interstitial lung Disease
- Chest wall Disease
- Neuromuscular Disease
What is the method of measure diffusion capacity?
Measuring Inhaled vs. Exhaled Carbon Monoxide
