PFTs Flashcards
Compliance
how stiff the lungs are
Indications for PFTS
-Screening and assessment of progression of Obstructive and Restrictive diseases
Pre-operative assessment
- > 60 yrs. of age
- Known pulmonary disease
- Obese
- H/O smoking
- Lengthy anesthesia expected
- Abdominal/ Thoracic operation
- Ventilator weaning
Normal FVC
80-120% predicted
FEV1
80-120% predicted
FEV1/FVC=FEV1%
> 0.7 predicted value (70%)
FVC
-Forced Vital Capacity
after the patient has taken in the deepest possible breath, this is the volume of air which can be forcibly and maximally exhaled out of the lungs until no more can be expired.
FEV1
-Forced Expiratory Volume in One Second
this is the volume of air which can be forcibly exhaled from the lungs in the first second of a forced expiratory maneuver
FEV1/FVC=FEV1%
it indicates what percentage of the total FVC was expelled from the lungs during the first second of forced exhalation - this number is called FEV1%, %FEV1 or FEV1/FVC ratio.
Interpretation of PFT
Don’t worry about the % predicted of 94% if FVC & FEV1 are normal
Step 1: Forced vital capacity (FVC) to see if it is within normal limits
Step 2: Look at the Forced expiratory volume in 1 second (FEV1) to see if it is within normal limits
Step 3: If both FVC and FEV1 are normal…. Patient has normal PFT
Step 4: If FVC and/or FEV1 are low, then disease is highly likely
Step 5: Go to % predicted for FEV1/FVC.
If the % predicted for FEV1/FVC is 88%-90% or higher
Restrictive Lung disease
If % predicted for FEV1/FVC is 69% or lower
pt. has OBSTRUCTIVE lung disease
Obstructive (Air Out)
If % predicted for FEV1/FVC is 69% or lower, then pt. has OBSTRUCTIVE lung disease
- COPD
- Asthma
- Bronchiectasis
- Cystic Fibrosis
Restrictive (Lung Expansion)
- If % predicted for FEV1/FVC is 88%-90% or higher…Pt. has RESTRICTIVE lung disease
- Interstitial lung disease
- Sarcoidosis
- Neuromuscular disease (ALS)
- Pulmonary Fibrosis
- Silicosis
- Asbestosis
