Resp 1 (second lecture--restrictive) Flashcards
What is infant respiratory distress syndrome? What causes it How do we detect it?
What it is: Neonatal respiratory distress syndrome (in the womb) and a Respiratory distress syndrome of newborn
-Hyaline membrane disease
-Cause: insufficient amount of surfactant
Usually due to prematurity or maternal diabetes, though some are due to a genetic deficiency
Testing:
-Fetal lung maturity testing (amniotic fluid)
-Lecithin-sphingomyelin ratio (L/S ratio)
-Phosphatidol choline
-Phosphatidol glycerol
Surfactant/albumin ratio
-Fluorescent polarization
-Shake Test
-High values good at predicting maturity, but low values not so good at predicting immaturity
-If suggests immaturity, can give mother steroids
What is the composition of pulmonary surfactant?
-Phospholipids 85% (includes 80% Phosphatidylcholine (lecithin) and
Phosphatidylglycerol, Phosphatidylinositol, Phosphatidylethanolamine , Sphingomyelin)
- Neutral Lipids and Cholesterol 5%
- Protein 10%
How does the L/S ratio change in the fetus?
It gets much steeper/higher around 40 weeks
How do we do a shake test and the results?
Equal amount of amniotic fluid and ethanol to a test tube
-if mature lung–than a lot of precipitate on top; if low value, not as good as predicting maturity
How do we treat infant respiratory distress syndrome after birth?
- Give oxygen along with CPAP
- Give exogenous surfactant
- But…can induce bronchopulmonary dysplasia and retinopathy of prematurity
- Fibrosis of the alveolar membrane which, despite its name, is not precancerous
- However…much less common with modern ventilation techniques
What is adult respiratory distress syndrome?
- Diffuse alveolar damage (Decreased surfactant; Inflammatory exudate; Hyaline membranes)
- Due to: Shock, Infections,Toxic gas inhalation, Ionizing radiation, Oxygen toxicity)
What are some chronic interstitial diseases?
Idiopathic pulmonary fibrosis
Pneumoconiosis
Hypersensitivity pneumonitis
Sarcodiosis
What is idiopathic pulmonary fibrosis?
- Typical patients: > 60 year-old male with occupational exposure to metal or wood dust
- Present with increasing SOB and dry cough
- Usually respiratory failure within 5 years
- “Usual interstitial pneumonia”
What is Pneumoconiosis?
Inhalation of particulate matter Coal dust Asbestos Silica Allergens
What is coal-worker’s Pneumoconiosis? what causes it?
- Coal dust inhaled and taken up by alveolar macrophages
- Resulting inflammation causes variable lung fibrosis
What are other types of pneumoconiosis besides coal-workers?
- Silica and asbestos have similar effects
- Silica tends to be worse than coal, because it is toxic to macrophages
- Asbestosis is difficult to differentiate from IPF unless you can see asbestos fibers
-Hypersensitivity Alveolitis
Organic particles such as cotton, sugar cane, bird feces, mold
A type III hypersensitivity reaction can occur
What is sarcoidosis?
-Often presents with fatigue, weight loss, arthralgia, SOB, dry cough
-Multisystem disease with prominent findings in the lung
Skin –> erythema nodusum
Joints–> increased osteoclast activity
Heart –> fibrosis
CNS –> depends on location
? Autoimmune disease
Massively enlarged hilar lymph nodes
Alveolar fibrosis with noncaseating granulomas
What other types of diseases cause lung fibrosis?
Other autoimmune diseases
What is a pulmonary embolus? how do we make a diagnosis?
- Venous thrombus usually from lower extremities; much less likely affects upper extremities or right heart (mural thrombus)
- Acute onset of chest pain and SOB
Diagnostic options
-D-dimer (sensitive, not specific)
-Spiral CT or VQ scan (may miss small emboli)
Angiography (best diagnostically, but highest risk)
Lower extremity ultrasound
Autopsy
What is the outcome of a pulmonary embolus if a patient survives it?
infarct of pulmonary tissue - especially with bronchial blood supply compromised
