lung function tests Flashcards
volume time curve process
noseclip
inhale to TLC
wrap lips around mouth piece
exhale as hard as possible
until residual vol reached - or exhaled as 6secs
look for slow starts, early stops, intramanouver variability
vol time curve with COPD
everything is reduced
vol time curve with restriction
rate unchanged
volume in is worse
Peak flow protocol
noseclip
inhale to TLC
wrap lips around mouthpiece
does not have to reach RV - looking at rate
repeat at least twice - take the highest measurement
Flow-vol loop protocol
noseclip
wrap lips around mouthpiece
1 TB
inhale steadily to TLC
exhale as hard and fast as possible - RV
immediately inhale to TLC - reflex inspiration
look for inconsistencies with clinical picture - interrupted flow data
what can you see on a flow vol loop
forced exp rate
peak exp more than peak insp - takes more effort
steady decay of flow rate - linear
inspiration is downward deflection
expiration is the upward deflection
flow vol envelope - never go out of the line
COPD flow vol loop
mild:
peak exp flow rate lower
vol increased - lungs larger - larder vol, smaller SA
coving in exhalation - bronchioles lower flow rate because of constriction and this is where the air moves through
severe: everything worse
restrictive disease
lower vol - displacement to the R
peak expiratory flow rate lower or unchanged - filling problem not gas moving problem
variable extrathoracic obstruction and flow vol loops
blunted insp curve
otherwise normal
Variable intrathoracic obstruction
blunted exp - otherwise normal
Fixed airway obstruction
blunted insp curve
blunted exp curve
both have the same flow limitation
otherwise normal
information from volume time curve
FVC - take highest point
FEV1 - normally all in 1s, onbstructive disorder 50%, restrictive - smaller vol but all out
FEV1/FVC ratio
peak exp flow rate - using steepest grad
use of peak flow
to determine the progression of asthma
