respiratory function tests Flashcards
what are the 3 basic measurements of spirometry?
volume
time
flow
what are the advantages of spirometry
Objective, non-invasive and sensitive to disease
what is spirometry used for?
o Assess lung disease
o Quantify lung impairment
o Monitor the effects of occupational/environmental exposures
o Determine effects of medications
how should a patient be positioned for spirometry?
Upright with feet flat on the floor. Legs uncrossed no use of abdominal muscles for leg position.
• Loose clothing – tight clothing can cause lower volumes
what technique should be used in spirometry?
o Deep breath taken in then full expiration performed through the mouthpiece
o Patient has to completely empty lungs then take in a quick inspiration, followed by a full expiration
what techniques ensure a good quality spirometry?
- Explosive start
- Maximal inspiration and expiration
- No glottis closure or cessation of airflow occurred
- No coughs
- The manoeuvre should meet the end-of-test criteria (exhaling for 6 s with 50 mL being exhaled in the last 2 s)
define tidal volume
amount of air you move into and out of your lungs during rest
define forced vital capacity
maximum volume of air into and out of your lungs in a single respiratory cycle
o FVC = IRC + TV + ERV
define inspiratory reserve volume
volume of air you can draw into your lungs
define expiratory reserve volume
volume of air you can expel from your lungs
define residual volume
volume of air that remains in the lungs even after maximal exhalation
how should you interpret spirometry data?
- Compare against reference values or predicted values
* In adults; age, height, sex and race are the main determinants
how does obstructive lung volume look on a flow-volume loop?
> normal – increased total lung capacity (TLC), functional residual capacity (FRC), residual volume (RV)
what is the FEV1/FVC ratio in obstructive lung volume?
FEV1 more dramatically reduced compared with FVC – decreased FEV1/FVC
how does a restrictive lung volume look on a flow-volume loop?
how does the FEV1/FVC ratio change in restrictive lung volume?
increased/normal FEV1/FVC ratio
what is considered a normal FEV1/FVC ratio?
Values above 70-80% = normal (age/gender/height adjusted
what is the ethnic variability in spirometry?
Caucasians have the highest predicted FEV1, African Americans have the lowest predicted Fev1
what is the benefit of exercise tests?
- Assess how much exercise a patient is able to manage
- Assess benefit of extra oxygen to help with daily activities
- Assess pre-operative fitness
- Part of a rehabilitation programme
