Interstitial Lung Disease (Raf) Flashcards
what is a hydrocarbon?
What are hydrocarbons?
* Petroleum solvents * Household cleaning products * Kerosene * Liquid polishes and waxes * Furniture polish * Typical age group for accidental ingestion: * Toddlers * Age <5 years * Often these products are stored in containers that look like beverage containers
How do hydrocarbons cause lung damage?
- Lung injury is through DIRECT aspiration
- Hypoxia is the MAIN issue, as opposed to hypercapnia. This is due to:
- Surfactant inactivation—>atelectasis and V/Q mismatch
- Bronchospasm
- Hydrocarbon vapours will displace alveolar gas
What type of lung damage do hydrocarbons cause?
- Autopsy samples in humans have shown:
- Necrosis of bronchi, bronchioles and alveolar tissue
- Hemorrhagic pulmonary edema
- Interstitial inflammation
- Thromboses
What is a non-infectious cause of pneumatoceles?
Hydrocarbon aspiration
Long term complication of hydrocarbon aspiration?
Peripheral small airway disease–>obstruction with low FEV1, air trapping so high RV/TLC
No increased bronchial reactivity
What features of hydrocarbons enable them to cause lung damage?
Hydrocarbons are vicious b/c:
- Low surface tension—>spread through tracheobronchial tree
- Low viscosity—>can go deep into lung
- High volatility—>high level of blood stream absorption, which causes CNS effects
Which surfactant disorders can have a delayed presentation?
- ABCA3
- Surfactant protein C
Lamellar body in SP-B?
Disorganized with large whirls and vaculoar inclusions.
Looks like a hole with inclusions, as opposed to a tree trunk
Lamellar body in ABCA3?
Fried egg (yolk and surrounding white of the egg)
Treatment for ABCA3 and SP-C?
Streoids, hydroxychloroquine, azithromycin
Which diseases cause non-caseating granulomas?
- Hypersensitivity pneumonitis
- Sarcoid
Which disease cause caseating granulomas?
- TB
- Granuomatosis with polyangitis
- IBD (necrobiotic nodules)
Pathology findings in HP?
- Alveolitis
- Giant cells
- Foamy alveolar macrophages
- Non-caseating granulomas
4 airway manifestations of SLE
- pleuritis with pleural effusion
- pulmonary embolus
- infection such as pseudomonas, PJP, CMV–>very important to rule out infection for pulmonary presentations of lupus
- shrinking lung syndrome
- chronic ILD
- pulmonary hemorrhage
Is routine CT for asymptomatic patients with lupus recommended?
No
Risk factors for acute chest syndrome
- Age, in particular 2-4 years of age, though pediatrics>adults
- Pulmonary infection, such as atypicals like mycoplasma
- lower HbF
- HbSS has more ACS than HbSC
- Asian haplotype
- Fat embolism
- Post op atelectasis
- Bronchospasm
- Higher WBC count
What is the biggest risk factor for sickle cell chronic lung disease?
- ACS
What is the relationship between asthma and sickle cell disease complications?
- Asthma and wheezing are independently associated with SCD complications
- ONLY wheezing is associated with ACS
What is ACS?
It's not a disease, but it's a syndrome of respiratory symptoms (fever, cough, dyspnea, hemoptysis) + new radiographic infiltrate in a patient with sickle cell. Variety of causes: - infectious - eg. mycoplasma - atelectasis - eg. post op - fat embolism
What type of lung disease is sickle cell chronic lung disease?
- fibrotic (interstitial fibrosis), difuse
- restrictive lung disease
Why are sickle cell disease at risk for OSA?
- functional asplenia—>compensatory T+A hypertrophy and extra medullary hematopoiesis
Sickle cell disease patient with obstruction, but no BD response. Etiology?
Consider causes for fixed airway obstruction, but can also have obstruction in sickle cell due to increased pulmonary capillary blood volume.
In sickle cell patients with suspected hypoxemia, how should this be confirmed?
Poor correlation between SpO2 and arterial blood gas, so should get PaO2 (blood gas)
What are signs of severe acute chest syndrome?
- Multilobar disease
- increased hypoxia
- increased RR
- low platelets
Which drug is strongly not recommended for PH management in sickle cell disease patient?
- phosphodiesterase inhibitors
Sickle cell patient with wheezing. Approach to investigation?
- PFT with pre/post bronchodilator testing
- Airway hyper-reactivity challenge tests, such as with exercise or cold air
- Methacholine challenge is NOT advised since this can cause ACS
- Key point: wheezing in SCD patient should NOT be labelled as asthma right away since there “other causes” (Kendig’s doesn’t go into details, but presumably the SCD itself with changes in pulmonary blood volume). That being said, may have lower threshold for treating for possible asthma since wheezing is a risk factor for ACS and both wheezing and asthma are independently risk factors for VOC
Sickle cell patient with dyspnea during exercise. DDx?
- Pulmonary hypertension
- Sickle cell chronic lung disease
- (Sleep disordered breathing is a co-morbidity that may be a role, but wouldn’t be top on the differential)
- Obstructive disease–asthma or wheezing (which seems to be intrinsically related to SCD)
Why is oximetry not reliable for SCD?
- increased carboxyhemoglobin in patients with sickle cell disease since faster Hb turnover. Most older oximeters in the hospital can’t differentiate between carboxy and oxygenated hemoglobin
- HbS absorbs light at a different frequency than HbA
Appearance of lamellar body in SP-B and ABCA3?
SP-B: abnormally formed lamellar body with large whorls and vacuolar inclusions
ABCA3: small and dense lamellar body, with eccentrically placed inclusions–>appearance of fried egg
BAL findings in HP?
Lymphocytosis
Decreased CD4/CD8 ratio (since there is predominance of CD8 cells)
increased NK cells
Immune pathogenesis of HP?
Sensitization to inhaled antigen–>alveolitis, with accumulation of neutrophils in the alveoli in first 48 hours–>then, increased lymphocytes and macrophages with prodominance of CD8 cells
- Both type 3 and type 4 cell mediated immune responses are involved, but there is no immune complex deposition in the lung
Patient with lupus presents with pleural effusion. Differential?
Infection is high on the differential! Patients with lupus are at high risk for pulmonary infection, even in the absence of drug side effects
- Inflammatory: pleuritis/Serositis
- Transudative due to renal failure or cardiac involvement (renal involvement would be more common)
Lupus patient who presents with fever, cough, chest pain, new infiltrate on CXR. DDx?
- Infection!!- they are at risk for opportunisitc infections like aspergillus, PJP, pseudomonas , CMV
- In general for acute pulmonary symptoms in lupus patient, think about PE, though that wouldn’t fit with fever
Other less common: - DAH, which is more likely if associated nephritis, drop in Hb or hemoptysis
- Acute pneumonitis (but this would pretty much be a diagnosis of exclusion)
Lupus patient with chronic dyspnea with exercise, chronic cough. DDx?
- chronic ILD
- pulmonary hypertension
Lupus patient with PFT showing restriction, DDx?
- chronic ILD
- Shrinking lung syndrome - I think normal DLCO corrected for VA, since there’s no parenchymal disease
- Pleural effusion
- ?DAH, but may expect increased DLCO if acute hemorrhage
