Restrictive/Inflammatory Lung Disease Flashcards
How is restrictive physiology defined? (PFT values)
Total Lung Capacity less than 80% predicted.
Functional Residual Capacity (Thoracic Gas Volume) less than 80% predicted.
Symmetrically reduced FEV1 and FVC (ratio still the same)
Restrictive physiology may be caused by ______ in lung elastic recoil or disease in the ______ or _____.
Increase, chest wall, pleura
What is the relaxation pressure?
Relaxation pressure is the measure of the total compliance of a system. This takes the compliance of the chest wall as well as the compliance of the lung into account.
True or False: The pressure-volume curves that we typically look at are only depicting the lung compliance, not chest complaince.
True! This is why changes in the chest wall compliance do not affect the slope of the curve, they only shift the whole thing up or down.
What is elasticity?
Elasticity is the tendency of a structure to return to its initial form after deformation (e.g. springs with high elastic recoil (elastance) has stronger tendency to return to its resting state when stretched)
Compliance is the inverse of _____
elastance
Generally, ______ diseases make it hard to exhale and _______ diseases make it hard to inhale
obstructive, restrictive
Inflammation or scarring may expand the _____ and reduce _____
interstitium, compliance
How does pulmonary edema increase elastic recoil/decrease compliance?
Pulmonary edema can increase the mass of the interstitium making it thicker and stiff. It can also deplete surfactant and increase mass and stiffness of the parenchyma.
How can surfactant depletion increase elastic recoil/decrease compliance?
Surfactant depletion increases alveolar surface tension which leads to alveolar collapse
All alveolar filling processes increase _______ and decrease ____
elastance, compliance
Pleural effusion, Asbestos-related pleural plaque, and Kyphoscoliosis all ____ the overall _____ by decreasing ____ of the _____
decrease, compliance, compliance, chest wall
How can you determine between restrictive lung disease and restrictive physiology?
In restrictive lung disease, the slope of the P-V curve is reduced. In restrictive physiology, the slope of the P-V curve is preserved but the whole curve is shifted downloards.
DLCO/VA is reduced in restrictive disease but preserved in restrictive physiology.
True or False: Restrictive chest wall diseases generally do not cause gas exchange problems.
True. Restrictive chest wall (restrictive physiology) generally doesn’t cause gas exchange problems unless very severe.
How is gas exchange impaired in restrictive lung disease?
There is a loss of alveolar surface area due to decreased lung volumes and decreased alveolar volumes. Also, the thickening of the alveolar walls limits diffusion.
DLCO is corrected for _______ using helium dilution technique
alveolar volume (VA)
When there is restrictive physiology, DLCO will _____
decrease in proportion to volume but DLCO/VA (DLCO corrected for VA) is normal
When there is restrictive lung disease present, there is a reduction in _____
DLCO AND DLCO/VA
Note that with restrictive lung disease, DLCO is decreased and is still decreased even after correcting for alveolar volume (except for in patients with early stage pulmonary fibrosis). With restrictive physiology, the correction of alveolar volume will make the value normal
Name 4 acute restrictive processes
- Pulmonary edema
- ARDS/DAD
- Pneumonia
- Pleural effusion
Name 3 chronic restrictive processes
- Interstitial lung disease
- Pleural fibrosis/plaques
- Pleural effusion
Restrictive processes can be acute or chronic. What is more common?
Chronic
If a patient has reduced lung voluems AND reduced FEV1/FVC, do they have obstructive or restrictive disease?
They have a mix of obstructive and restrictive disease
Give 4 common examples of mixed obstructive disease
- coal miner (interstitial disease from occupation) who smokes (emphysema)
- obese person (chest wall restriction) with poorly controlled asthma (obstructive)
- combined pulmonary fibrosis and emphysema
- fibrotic hypersensitivity pneumonitis (causes mixed)
- sarcoidosis (causes mixed)
What is interstitial lung disease?
ILD is a heterogeneous group of disorders characterized by a combination of inflammation or scarring.
Pulmonary fibrosis is characterized by ___
scarring
How do patients with interstitial lung disease typically present? (5)
- Dyspnea with exertion
- Cough
- Subacute to insidious timing
- Restrictive PFTs with decreased DLCO
- Abnormal lung imaging
There are many kinds of interstitial lung disease (hundreds). Why is specific diagnosis for interstitial lung disease important?
It is important to be specific with diagnosis because prognosis varies a lot between different types of ILD.