Predicted values Flashcards
Normal spirometry
What is the meaning of repeatability?
Variation in measurement using repeat measurements under identical conditions (same patient on same piece of equipment by same operator under same environmental conditions).
What is the meaning of reproducibility?
Variation in measurement when there are different conditions (on patient on different days, using different spirometer and different operator).
What are sources of error?
-equipment
-environment
-procedures and protocols
-patient (compliance- operator giving similar info)
-physiologist (competency checks).
What is the repeatability criteria?
-3 technically acceptable results selected from up to 8 efforts
-shouldnt differ from next best values by 150ml
-report highest FEV1 and FVC (can come from any efforts)
When does lung development begin?
day 26 of gestation.
When do alveoli start to develop?
From week 24.
When does surfactant develop?
From week 22-24 (lungs will collapse with no surfactant).
What is the effect of ageing on the lungs?
-reduction in collagen and elastin
-loss of elasticity
-decrease in muscle tone
-exposure to pollution
-impaired nutrient supply
-reduction in cell membrane permeability
-increased rigidity of chest wall (skeleton not as flexible).
Difference in lungs for sex?
-children have similar lung vols until puberty
-males have broader shoulders, increase in trunk and chest dimensions
-given height, male lung vols larger than females
Difference in lungs for ethnicity?
Given height, Caucasians have greater lung vols than any other ethnicity.
How to create predicted values?
-representative sample for healthy subjects
-drawn from gen pop
-exclude those with resp disease
-past and present medical history
-physical examination
-chest x-ray findings
What are recommended reference values?
It depends on the organisation.
