Lung Flashcards
What are the 3 mechanisms of impaired alveolar oxygen diffusion?
- ↓ Surface area
- ↓ driving pressure
- diffusion distance
What 3 things can cause ↓surface area mediated alveolar-capillary oxygen diffusion impairment?
- alveolar destruction (COPD/emphysema)
- loss of capillaries (embolism, pulmonary HTN)
- alveolar filling defect (fluid, pus, blood)
What 2 things can cause alveolar-capillary oxygen diffusion impairment by ↓ driving pressure?
- bronchiole obstruction (asthma)
- alveolar filling defect (pneumonia)
What can cause alveolar-capillary oxygen diffusion impairment by ↑ diffusion distance?
wide alveolar capillary space (fibrosis, edema)
How does emphysema/COPD cause alveolar-capillary oxygen diffusion impairment? (i.e. via which mechanism)
alveolar destruction → ↓ surface area
How does a PE or pulmonary HTN cause alveolar-capillary oxygen diffusion impairment? (i.e. via which mechanism)
loss of capillaries → ↓ surface area
How does fluid, pus or blood cause alveolar-capillary oxygen diffusion impairment? (i.e. via which mechanism)
alveolar filling defect → ↓ surface area
How does asthma cause alveolar-capillary oxygen diffusion impairment? (i.e. via which mechanism)
bronchiole obstruction (inflammation) → ↓ driving pressure
How does pneumonia cause alveolar-capillary oxygen diffusion impairment? (i.e. via which mechanism)
alveolar filling defect→ ↓ driving pressure
How does fibrosis or edema cause alveolar-capillary oxygen diffusion impairment? (i.e. via which mechanism)
wide alveolar-capillary distance → ↑ diffusion distance
What is the MC pulmonary ssx?
dyspnea!
This spirometry reading, FEV1/FVC ratio < 70%, is dx of which type of lung dz?
obstructive
Is it possible to determine restrictive lung dz physiology from spirometry tests?
NO!! Need to do lung volume tests
subepithelial collagen deposition leading to ↑ bronchial wall thickness
severe asthma
Main inflammatory mediators of asthma
eosinophils
Airway inflammation is primarily mediated by CD4(+) T-cells and eosinophils in which airway dz?
asthma
Airway inflammation is primarily mediated by CD8(+) T-cells and M∅/ PMNs in which airway dz?
COPD
What are the 2 things necessary to dx COPD?
- evidence of airflow obstruction (FEV1/FVC < 70%)
- clinical ssx (cough, sputum prdn., or dyspnea)
2 useful tests (other than spirometry) used to dx asthma
- methacholine challenge test
- peak flow variation
What are the 4 pathologic locations restrictive thoracic disorders can occur?
- pleural cavity
- interstitium (lung parenchyma)
- Neuromuscular
- Thoracic/Extrathoracic
How are the timing of clinical ssx different b/w asthma and COPD?
- asthma: intermittent and variable
- COPD: persistent and progressive worsening
How does a patients cough differ b/w asthma and COPD?
- asthma: nocturnal cough or on exertion
- COPD: morning cough w/ sputum
What are the 2 broad categories of COPD? What are their characteristic pathologic findings?
- chronic bronchitis: inflammation & excess mucus d/t hyperplasia of mucous glands
- emphysema: breakdown of alveolar membranes
Compare the prevelance and mortality trends of asthma and COPD
- asthma: ↑prevelance, ↓mortality
- COPD: ↑prevelance, ↑mortality
How can asthma be fatal?
mucous plugs
How is the clinical dx of chronic bronchitis COPD defined?
presence of chronic productive cough for 3 months in each of 2 successive years in a patient in whom other causes of chronic cough have been excluded
What is the most significant pathologic feature of asthmatic bronchial airways?
reduced airway lumen area
What is a normal A-a gradient?
10
What can ↑ fremitus on lung exam indicate?
lung consolidation (e.g. pneumonia)
What are 3 things ↓ fremitus on lung physical exam indicate?
- pneumothorax
- pleural effusion
- emphysema
What is the normal percussive tone of the lung heard on physical exam?
resonant- air filled tissues produce a higher resonant tone
Give a pathologic example that can cause dullness to percussion on lung physical exam
lobar pneumonia
Give 2 pathologic example that can cause a hyperresonant sound to percussion on lung physical exam
- emphysema
- pneumothorax
What is stridor?
inspiratory wheeze
What are 3 criteria that factor into the 4 COPD classifications by GOLD criteria?
- classification of airway flow obstruction (1,2,3,4)
- symptoms measured by mMRC (0-1, ≥2) or CAT (< 10, >10) score
- exacerbation hx (0, 1, ≥2)
Which medication used alone (monotherapy) is contraindicated in COPD pts. ? How can it be used?
inhaled corticosteroids (ICS)
-used in combination w/ long acting β-agonist (LABA)
Which medication used alone (monotherapy) is contraindicated in asthma pts. ?
long acting β-agonists
What factor is key in the tx of COPD?
smoking cessation
What class of drugs are the cornerstone of asthma therapy?
inhaled corticosteroids
Which values are expected to be low on a lung volumes test in a patient w/ restrictive lung dz?
- RV
- FRC (RV + ERV)
- TLC (IRV + TV + ERV + RV)
In what lung dz might you see respiratory acidosis? Why?
COPD→ obstructive, can’t get air out →CO2 can’t get out either
What are 3 radiographic findings found in patients w/ COPD?
- hyperinflation
- ↑ retrosternal airspace
- bullae
When is tx w/ supplemental oxygen indicated in COPD patients?
if they have baseline, exercise, or sleep related pO2 < 55 OR SpO2 ≤ 88% or ≤ 89% w/ evidence of cor pulmonale
How is compliance of the lung altered in obstructive vs. restrictive lung dz?
obstructive: ↑compliance
restrictive: ↓compliance
How does long term lung damage in asthma patients occur (3 steps)? At what stage of asthma does this begin to happen?
acute response →chronic inflammation →airway remodeling =
long-term damage
-occurs even in mild asthma!
What is the purpose of a metacholine challenge test in asthma patients?
to determine Rx dose (highly sensitive) → use muscarinic agonist → determine dose @ which FEV1 ↓20%
What is the pathophysiology of airway remodeling in asthma?
cell proliferation and ↑ECM
What are 3 non-pharmalogical tx for COPD?
- oxygen therapy
- vaccination
- pulmonary rehab
What are 2 types of drugs that can be used to tx COPD exacerbations?
- Roflumilast (PDE-4 inhibitor)→ use in combo w/ LABA
- Azithromycin (Abx)
What type of procedure can an asthma patient have done if they are not responding to Rx?
bronchialthermoplasty → ↓ airway mm.
What are the 4 classifications of asthma patients (+ ssx and FEV1) used for tx?
- mild-intermittent
(FEV1 >80%, exacerbations ≤ 1-2x/wk + nighttime ssx ≤ 1-2x/mo.)
- mild-persistant
(FEV1 > 80%, exacerbations > 2x/wk + nighttime ssx > 2x/mo.)
- moderate-persistant
(FEV1 > 60%, exacerbations > 2x/wk + nighttime ssx > 1x/wk.)
- severe-persistant
(FEV1 < 60%, frequent exacerbations & nighttime ssx)
What are the 4 broad categories of restrictive thoracic disorders?
- pleural
- insterstitial (lung parenchyma)
- neuromuscular
- thoracic/extrathoracic