B4.37 - Evaluating Pulmonary Function Tests Flashcards
Indications for PFT
Screening
Evaluation of respiratory symptom or sign
Grading severity of respiratory disease
Following progression of respiratory disease
Monitoring response to therapy
Monitoring occupational, drug or radiation toxicity
Predicting prognosis
predicting post op pulmonary risk
assessing disability/impairment
what does spirometry measure
how fast and much you air you breath out
what are teh ATS acceptability criteria for FVC
Good start of test
Smooth continuous curve
Satisfactory exhalation
what determines if the start of the test was good enough
extrapolated voluem <5% of FVC or 150 mL
what is the minimun time an exhalation must be for it to be acceptable
6 seconds
10 is prefered
what are ATS reproducability criteria for FVC
after 3 acceptable maneuvers, the two largest FVC adn FEV1 are within i150 mL of each other
what is depicted her
excellent effort
the goal
what is depicted here
hesitating start
what is depicted here
submaximal effort
what is depicted here
rainbow curve
normal in young, non smoking females
early termination
coughing
subject briefly stopped exhaling
the “knee”
normal in young non smokers
what are gas dilution methods
nitrogen washout and helium dilution
takes advantage of inert, poorly soluble gas of known concentration
a way to measure lung volume
what is a non gas way of measuring lung volume
body box
equation for Vf (unknown lung volume)
Vf = (change in V/change in P) (PB)
what is TLC
total lung capacity
FRC + IC
or
RV + VC
what is RV
residual volume
FRC - ERV
what is the reference equation used for finding reference ranges for spirometry
from NHANESIII
FEV1 - 80-120
FVC - 80-120
what is an obstructive pulmonary defect
a disporportionate reduction of maximal airflow from the lung with respect to the maximal volume (FVC) that can be displaced from the lung. Indicates expiratory airlow limitation
what is a normal FEV/FVC
>.7 is the cutoff for normal
what do these indicate and why
Obstructive pulmonary defect
because the FEV1/FVC ration is low and expiratory phase of flow/volume loop is lower than expected indicating an issue with exhalation
causes of obstructive pulmonary defect
Asthma
COPD
bronchiectasis
Obliterative bronchiolitis
LAM
Diffues panbronchiolitis
what is restrictive pulmonary defect
characterized physiologically by reduction in TLC below the 5th percentile of normal distribution.
what can a restrictive pulmonary defect be inferred
when theres FVC that is reduced and FEV1/FVC ration is nromal or increased.
what does this demonstrate
restrictive pulmonary defect
Note: normal FEV1/FVC ration
Narrower exhalation because of reduced overall volume
what are restrictive defects in the lung
resection
atelectasis
stiff lung (fibrosis)
CHF
Thickened pleura
tumor
what are restrictive defects in the pleual cavity
effusion
enlarged heart
tumor
what are restrictive defects in the chest wall
scleroderma
ascites
pregnancy
obesity
kyphoscoliosis
splinting due to pain
what are restrictive defects in muscle
neuromuscular disease
old polio
paralyzed diaphragm
what is a mixed pulmonary defect
coexistence of obstruction and restriction
defined physiologically when both the FEV1/FVC ratio and the TLC are decreased
what are the categories of severity of spirometric abnormalities
what is a bronchodilator response
usually four separate doses of albuterol is given by metered dose inhaler using a space. Tests repeated after 15 minute delay
a >12% and 200mL increased in FEV1 or FVC meets critera for bronchodilator response
can you differentiate asthma and COPD with a bronchodilator response
no bitch
differentiate between extrathoracic, intrathoracic, varable and fixed airway obstructions
extrathoracic - above suprasternal notch
intrathoracic - between suprasternal notch and carina
Variable - lesion narrows and decreases flow excessively during one phase of respiration
fixed - narrowing causes decreased flow equally during both phases of respiration
examples of variable extrathoracic lesions
vocal chord paralysis/dysfunction
tracheomalacia
goiter
examples of variable intrathoracic lesions
traheomalacia
malignant tracheal lesions
tracheal stricture
fixed lesions
tracheal stenosis
vocal cord paralysis
vocal cord malignancy
name the type of obstruction
variable extrathoracic
name the type of obstruction
variable intrathoracic
name the obstruction
fixed major airway obstruction
