PFT Flashcards

Restrictive pattern
- low volume and normal flow
- Reduced FVC
- Normal FEV1/FVC ratio
- obesity, Pulmonary fibrosis, interstitial lung disease, muscular dystrophy, scoliosis, sarcoidosis, pulmonary embolus

small airway obstruction
- Low flow, FVC normal or low
- Asthma exacerbation
- emphysema
- chronic bronchitis
- Bronchodilators, corticosteriods

fixed large airway obstruction
- Reduced flows on insp and exp
- tracheostenosis
- reduced vols and flows

Variable intrathoracic large airway obstruction
- Expiratory curve flattened
- flows and volumes are impacted on exhalation only
- inside thorax
- tracheal CA
- tracheal malacia(soft trachea)
- tumor
- tx: surgical intervention

Variable extrathoracic large airway obstruction
- Inspiratory curve flattened- reduced flow and volume
- outside of thorax
- laryngeal CA
- vocal cord dysfunction - speech therapy
When performing spirometry it is important that values are reported at?
BTPS
GOLD Standard
Stage 0
At-risk- symptoms present, Normal spirometry
Avoid risk factors
Get influenza vaccine
GOLD Standard
Stage 1
- mild
- FEV1/FVC <70%
- FEV1 > or equal 80%
- Add short acting Bronchodilator PRN
GOLD Standard
Stage 2A
- Moderate
- FEV1/FVC <70%
- 50%<= FEV1<=80%
- Add LABA and rehab
GOLD Standard
Stage 2B
- Moderate
- FEV1/FVC <70%
- 30%<=FEV1<=50%
- Add inhaled steroids if repeated exacerbations
GOLD Standard
Stage 3
- FEV1/FVC <70%
- FEV1<=30% or PaO2<60 or right heart failure
- Add long term O2 if chronic resp failure, ? surgical rx
Nitrogen washout
- Measures FRC by measuring volume of N2 in lungs at end exhalation
- open circuit- no rebeathing
- only measures gas with communication airways (Not trapped gas)
Helium dilution
- Closed circuit (rebreathing)
- pt. FRC is mixed with a second separate gas with know volume and %
- 10% He (or other inert gas)
- 21% O2
- 69% N2
- gas is rebreathed until helium diluted to equilibrium
DLCO
- used to assess diffusion of CO across alveolar membrane
- pt exhales to RV, then maximally inhales gas mixure
What effects DLCO results?
- Direct relationship
- surface area of ACM
- capillary blood vol
- lung volume active in gas exchange
- amount of Hb
- Inversely
- thickness of ACM
- carboxyhemoglobin level (smoker)
- alveolar O2 tension (PAO2)
What causes decreased DLCO?
- interstital lung disease (restrictive fibrosis)
- emphysema
- Pulmonary vascular disease (vasculitis, Pulm HTN)
- pneumonia
- sarcoidosis
What could cause increased DLCO?
- increased VA
- polycythemia
- exercise
- normal or high with asthma
FENO
- Fractional exhaled nitric oxide
- evaluates eosinophilic airway inflammation
- increased value: asthma not in control or COPD exacerbation (nonmed compliance)
- Decreased value: CF and smokers
- Normal adult: 15-25 ppb
- Normal child: 5-22 ppb
Bronchoprovocation study
- Determination of airway hyper-reactivity
- Precations
- Resuscitation equipment on hand
- MD immediately available
- Meds to reverse the provocation agent
- A positive test is when a 20 DECREASE in FEV1 is observed
What values show Obstruction in spirometry?
- Low FEV1/FVC defines the presence of obstruction
- FEV1 determines the severity
What values show restriction on spirometry?
- Low FVC with normal or high FEV1/FVC suggests restrictive lung disease
- Measurement of TLC used to confirm restriction and grade severity
The predicted FVC value for African American is?
10-15% less than that for caucasions
what spirometry parameter would you recommend to assist a patient with asthma in monitoring their day to day symptoms?
PEF
What is the proper method to minimize cross contamination between patients performing tests that only require exhalation into the apparatus?
- Change only those elements through which rebreathing occurs
- Place a disposable bacterial filter between the patient and breathing circuit