Week 2 - part 2 Pulmonary function testing Flashcards
What is a normal FEV1/FVC ratio?
0.75- 0.85
Obstructive Lung disease
Increase in RESISTANCE to airflow due to a partial or complete obstruction of the airway passages in the lungs at any level.
LOW FEV1
Low FEV1/FVC ratio
Normal FVC
Hyperinflated lungs, good compliance, bad elastic recoil.
Examples: Asthma COPD Bronchiectasis cystic fibrosis
Restrictive Lung disease
Reduced expasion of lung parenchyma & decreased total lung capacity
Low FEV1
Normal /slightly higher FEV1/FVC ratio
Low FVC due to reduced expansion
Examples:
Interstitial lung disease(fibrosis)
CW Abnormalities
Respiratory muscle weakness
Explain Peak expiratory flow rate diagrams
Inspiration is negative pressure t/f is at bottom of diagram
with chronic bronchitis flow is less for expiration because it is an obstructive lung disease
Severity of COPD
What is the scale?
FEV1 as a percentage of normal predicted FEV1 is used to classify severity of COPD
60-79% Mild
40-59 % Mod
40 or less % Severe
What does the Body box measure?
TLC and subdivisions
RV is 20-35% of TLC in young adults
Increases with age
What are 2 tests of Gas exchange?
Arterial blood gas analysis (ABG’s)
Carbon monoxide diffusing capacity
(gas transfer)
What do arterial blood gasses tell us?
Oxygenation
Acid base balance
Severity of respiratory failure
PaO2, PaCO2, SaO2
pulse oximeter will give continous SpO2 readings
Carbon monoxide transfer factor (TLCO)
diffusing capacity)(DLCO
Rate of transfer of CO from inspired air to pulmonary capillary blood
State of the alveolar-capillary membrane of gas exchange surface of the lung.
decreased (TLCO)= decrease surface area or quality of alveolar- capillary bed
- patients with very low transfer factor may desaturate on excercise
Often low in:
Interstitial lung disease
SevereCW abnormalities
Emphysema where severe
What does TLCO stand for
Carbon monoxide transfer factor
decreased (TLCO)= decrease surface area or quality of alveolar- capillary bed
