Bedside tests - Pulmonary Function Tests Flashcards
What are the 3 tests done?
Spirometry
Peak expiratory flow
Diffusing capacity
PEF:
What does it stand for?
How is it done?
What units are used?
How many times do you get the patient to do it?
Peak expiratory flow
Maximal forced expiration through a peak flow meter
L/min
3 times - best of 3
Diffusing capacity (DLCO):
What does it measure?
What does a low value suggest?
What does a high value suggest?
Gas transfer in the lung
Looks at diffusing capacity of CO
Low = emphysema
High - interstitial lung disease
Spirometry:
What does the following mean:
- FEV1?
- FVC
When is it used? - 2
Forced expiratory volume for 1 second - PEF1 similar but used more as it is more convenient and easier to do.
{Volume exhaled in 1st second after deep inspiration and forced expiration}
Forced vital capacity
{Total volume of air patient can breath out in 1 breath}
Looks at airflow obstruction
Helps classify COPD severity
Spirometry:
Obstructive Pattern:
FEV1 is reduced (<80% of predicted value)!!
Why is the FVC reduced to a lesser extent than FEV1?
Is the FEV1/FVC ratio increased or decreased?
Obstructive so they are able to get the air out eventually but it takes longer
Decreased ratio
Spirometry:
Restrictive pattern:
Why is the FEV1/FVC ratio normal?.
FEV1 and FVC are both reduced
Whereas before FEV1 is reduced more in obstructive disease
Spirometry:
Examples of obstructive diseases? - 4
Examples of restrictive diseases? - 2
Asthma
Bronchiectasis
COPD
CF
Fibrosis
Sarcoidosis
https: //www.youtube.com/watch?v=yJzbiVUL58Y
https: //www.youtube.com/watch?v=gJlRmu0o1ns
https: //www.youtube.com/watch?v=yJzbiVUL58Y
https: //www.youtube.com/watch?v=gJlRmu0o1ns
Obstructive vs Restrictive Disease:
Where is the problem primarily based in obstructive?
Where is the problem primarily based in restrictive?
More proximal - bronchi, bronchioles
More distal - lung parenchyma (the portion of the lung involved in gas transfer - the alveoli, alveolar ducts and respiratory bronchioles).
Obstructive vs Restrictive Disease:
What breathing abnormality do patients with obstructive lung disease have?
What breathing abnormality do patients with restrictive lung disease have?
Cannot get the air out - obstruct - stop
Cannot get the air in - restricted from filling
Obstructive vs Restrictive Disease:
Examples of obstructive disease - 4
Examples of extrinsic (its not the lungs fault) causes of restrictive lung disease
Examples of intrinsic (its the lungs fault) causes of restrictive lung disease:
- Occupational - 2
- Autoimmune - 2
- Drug-induced - A
- IPF - what is it?
Asthma COPD (emphysema and chronic bronchitis) Bronchiectasis Bronchitis ---- Chest wall deformity Neurological defect - diaphragmatic paralysis, ALS Respiratory centre depression - barbiturates, alcohol, opiates Abdomen - ascites ----- Silicosis Asbestosis
Rheumatoid
Scleroderma
Amiodarone
Idiopathic pulmonary fibrosis
Obstructive vs Restrictive Disease:
FVC is the reduced in both but more in restrictive as less able to fill lungs!!!
Why is FEV1 low in both?
FEV1/FVC for obstructive - how can you remember is it low?
FEV1/FVC for restrictive - how can you remember is it normal or high?
Obs - low as cannot get the air out
Oppresses the ratio
Raises the ratio
Remains the same
Obstructive vs Restrictive Disease:
Vital capacity - is it high or low?
Why is the residual volume (RV) in obstructive disease increased? What are they typically referred to as?
Does the residual volume (RV) in restrictive remain normal or reduce?
Low in both
Obstructive disease increases lung resistance making breathing out harder and slower. This results in increased residual lung volume - the air just doesn’t leave
Barrel chest - bloaters
It remains the same
Obstructive vs Restrictive Disease:
Why do patients with O disease hypoventilate?
Why do patients with R disease hyperventilate?
Don’t get all the air out in one normal breath so takes longer for them to get the air out so slows breathing rate
Since the lung is restricted from filling, there is a reflex which increases the respiratory rate leading to hyperventilation
Reversibility:
What medication should patients stop before spirometry?
What does reversibility suggest?
What does not reversibility suggest?
What does partial reversibility suggest?
Bronchodilators:
- Short acting beta-2 agonists - 6 hrs prior
- Long-acting beta-2 agonists - 12 hrs prior
Suggests asthma - as meds helping to open bronchioles
Suggests COPD - it will never go back to baseline
Mixed picture
