Flashcards in Pulmonary Function Tests Deck (15):
in spirometry of an asthmatic: FEV1 is _____
in spirometry of an asthmatic: FVC is ______
only situation in which FVC is reduced is when ______
the patient has COPD
(An exception is when asthma has remodelled the airways, causing FVC to decrease).
Expiratory flow rate is from TLC to RV. What are the units?
L/s (litres per second)
PEFR is _____ in obstructive, and _____ in restrictive
FEV1 is _____ in obstructive, and _____ in restrictive
FVC is _____ in obstructive, and _____ in restrictive
normal in asthma and reduced in COPD, reduced
FEV1/ FVC ratio is _____ in obstructive, and _____ in restrictive
reduced, normal (sometimes high)
FEV1 response to B2-agonist is ______ in obstructive, and ______ in restrictive
>15% in asthma and <15% in COPD, no response
bronchial challenge testing
using a marker of airway hyper-responsiveness (e.g. histamine). Finding the concentration required to produce a 20% drop in FEV1. Or using allergens/ chemicals to diagnose occupational asthma
for asthmatics: they will have decreased FEV1 and decreased PEFR post-exercise.
In Interstitial Lung disease: there is decreased SaO2 during exercise
static lung volumes
these are effort independent tests e.g. helium dilution/ N2 washout to find the functional residual capacity.
Transfer factor (Diffusing Capacity)
CO's diffusion across alveolar-capillary barrier (AKA single breath diffusing capacity).
TLCO (total lung transfer for CO) is decreased in anaemia (not enough Hb), emphysema (not enough lung tissue - holes), Interstitial lung disease (fibrotic), pulmonary oedema (fluid), pulmonary emboli, bronchiectesis
how is airway resistance measured?
whole body plethymography, or (more easily) by impulse oscillometry