LFTs Flashcards
(19 cards)
What is FEV1?
• Forced expiratory volume in 1s (FEV1): the volume exhaled in the first second after deep inspiration and forced expiration, similar to PEFR.
What is FVC?
• Forced vital capacity (FVC): the total volume of air that the patient can forcibly exhale in one breath.
What does FEV1/FVC ratio of <0.7 show?
Obstructive disease
What are the Spirometry findings in obstructive lung disease? (3)
• Reduced FEV1 (<80% of the predicted normal)
• Reduced FVC (but to a lesser extent than FEV1)
• FEV1/FVC ratio reduced (<0.7)
What does a FEV1/FVC ratio of >0.7 show?
Restrictive lung disease
What are the Spirometry findings in restrictive lung disease? (3)
• Reduced FEV1 (<80% of the predicted normal)
• Reduced FVC (<80% of the predicted normal)
• FEV1/FVC ratio normal (>0.7)
What should be stopped before reversibility testing in Spirometry and for how long? (2)
• Short-acting beta-2-agonists should be stopped 6 hours prior to testing.
• Long-acting beta-2-agonists should be stopped 12 hours prior to testing.
What does presence of reversibility in Spirometry suggest?
Asthma
What does partial reversibility in Spirometry show?
Coexisting diagnosis of asthma and other obstructive disease
What are 5 causes of obstructive lung disease?
• COPD
• Asthma
• Emphysema
• Bronchiectasis
• Cystic fibrosis
What are the pulmonary (5) and non-pulmonary (4) causes of restrictive lung disease?
Pulmonary
• Pulmonary fibrosis
• Pneumoconiosis
• Pulmonary oedema
• Lobectomy/pneumonectomy
• Parenchymal lung tumours
Non-pulmonary
• Skeletal abnormalities (e.g. kyphoscoliosis)
• Neuromuscular diseases (e.g. motor neuron disease, myasthenia gravis, Guillan-Barre syndrome)
• Connective tissue diseases
• Obesity or pregnancy
What is PEFR?
Peak expiratory flow rate
Measure peak expiratory flow out of the lungs to show obstruction
When is pefr used?
To assess severity of asthma
What is FeNo?
Fractional exhaled nitric oxide in breath of patients
When is FeNO used?
Biomarker for asthma as it shows level of inflammation
Aids in diagnosis of asthma
What is DLCO?
Lung diffusion test
Pulmonary function test that shows how much oxygen moves from lungs to blood by measureing carbon mono side
What factors can determine oxygen transfer in a DLCO test? (5)
• The amount of surface area in your alveoli.
• The amount of blood in your capillaries.
• The concentration of hemoglobin (a protein that carries oxygen) in your blood.
• The thickness of the membrane between your alveoli and capillaries.
• Excess fluid in your alveoli.
What can cause a low DLCO? (7)
• Smoking.
• Cystic fibrosis.
• COPD.
• Emphysema.
• Sarcoidosis and other interstitial lung diseases.
• Heart and blood conditions, like pulmonary embolism, pulmonary arterial hypertension, congestive heart failure and anaemia.
• Autoimmune disorders like mixed connective tissue disease, scleroderma and lupus (SLE).
What can cause a high DLCO? (8)
○ Obesity.
○ Asthma.
○ Exercising before the test.
○ High altitude.
○ Bleeding in your lungs.
○ Cardiac shunt.
○ Heart failure.
○ Polycythemia vera.
