Lung function tests Flashcards
Contraindications for spirometry
Eye surgery
Thoracic/abdominal/brain/ear/ENT or vascular surgery
Lung disease - pneumothorax, haemoptysis, PE, chest infection
Ear infection
CVS disease
Aneurysms
Acute nausea, omitting, diarrhoea
Infection control
Confused/demented
When are pulmonary function tests used?
Diagnosis if respiratory symptoms
Establish progression and severity
Assess treatment response
Monitor patients on meds with lung toxicity - eg chemotherapy
What do pulmonary function tests measure?
Lung volume
Rate of airflow
Gas exchange
Methods/instrument examples of PFT’s
Peak flow rate meter
Spirometry
Diffusing capacity for carbon monoxide
Body plethysmography
What is peak expiratory flow rate?
Maximum airflow rate attained during forced expiration in L/s (PEFR)
Attained using peak flow meter
Normal peak flow
Greater than or equal to 80% of predicted average value
What is PEFR predicted average based on?
Height
Gender
Age
Ethnicity?
What is a peak flow meter useful for?
Monitoring people with asthma - give baseline when asymptomatic
When asthmatics notice a decrease in their normal peak flow they can seek medical help sooner and keep it well managed
What is spirometry used for?
Lung volumes
Airflow - volumes are measured over time
Produces graphs (FEV1 and FVC)
LEARN the lung volume and capacity graph
Page 10 of LFT lecture
Tidal volume define
Amount of air moving in and out of lungs at rest
Inspiratory reserve volume define
Additional amount of air that can be inhaled after normal inspiration (air we can breathe in above tidal volume)
These are forced and not natural
Expiratory reserve volume define
Additional amount f air that can be exhaled after normal expiration (ow much more air we can breathe out below tidal volume on graph)
These are forced and not natural
What is residual volume?
Volume of air remaining in lungs after forceful expiration
Inspiratory capcacity?
TOTAL volume of air that can be inspired after normal expiration
(tidal volume and inspiratory reserve)
ie deepest breathe in
What is functional residual capacity?
Volume of air present in lungs at the end of a passive expiration (NOT FORCED LIKE RESIDUAL VOLUME)
= expiratory reserve volume + residual volume
What is vital capacity?
Volume of air EXHALED after maximum inspiration
(inspiratory reserve + tidal + expiratory reserve)
Total lung capacity?
volume of air contained in lungs at end of maximal inspiration
(TV + inspiratory reserve volume + expiratory reserve volume + residual volume)
FEV1
Maximum volume of air that can be forcefully exhaled within 1 second after maximal inspiration
FVC
Total volume of air breathed out following maximal inhalation
Occurs over 6 seconds