Lung: Abcess, Bronchiectasis, Asthma Flashcards
Lung abscess: definition, risk factors
Definition: local suppurative process producing necrosis of lung tissue
Risk factors:
- Dental procedure (because anaerobic org of oral cavity)
- Sinobronchial infection
- Bronchiectasis
Lung abscess: COMMON causative organisms
Organisms: 1. Anaerobes of oral cavity A. Bacteroides B. Fusobacterium C. Peptococcus 2. Streptococcus 3. Staph aureus
Any organism can produce an abscess though
Lung abscess: causes
Mm: A E I M N P
- Aspiration
A. MOST FREQUENT CAUSE
B. Especially when cough reflex is suppressed eg. Acute Alcoholism, coma, anaesthesia, gingivodental sepsis, sinusitis. - Embolism (septic embolism)
A. From thrombophlebitis giving off infected emboli
B. Vegetations of IE - Infection (secondary to pneumonia)
A. Especially in Staph aureus, pneumococcus type 3, Kleb pneumoniae - Misc:
A. Direct penetrating trauma
B. Hematogenous seeding
C. Spread of infection from neighbouring organs eg esophagus, spine, sub phrenic space, pleural cavity - Neoplasia
A. Post obstructive pneumonia - Primary cryptogenic lung abscess (idiopathic)
Lung abscess: Gross morphology
Gross:
1. Pus filled cavity of variable size
A. Maybe air filled if connected to airways
2. Single or multiple
A. Aspiration associated is usually single
B. Post pneumonia, septic embolism, pyemic abscess multiple
3. May affect any part of the lung
A. Aspiration associated usually on the right (cuz right bronchus straighter)
B. Rest anywhere
Lung abscess histology, clinical presentation
Histology:
Suppurative destruction of lung parenchyma with CAVITY formation
C/p: (much like bronchiectasis) (only in productive cough) 1. Fever 2. Cough 3. Sputum A. copious amount B. foul smelling C. purulent or sanguineous 4. Clubbing (few weeks after onset) 5. Chest pain 6. Weight loss
Lung abscess complication
1. Local: A. Hemorrhage B. Pleural involvement 2. Systemic: A. Metastatic abscess: BRAIN ABSCESS B. Meningitis (from septic emboli) C. Secondary Amyloidosis (if long standing)
Define asthma
-Asthma is a chronic disorder
-of the conducting airways
-usually caused by an immunological reaction
-marked by
A. episodic bronchoconstriction
>due to increased airway sensitivity
>to a variety of stimuli
B. inflammation of the bronchial walls
C. increased mucus secretion
Asthma C/P
recurrent episodes of A. wheezing B. breathlessness C. chest tightness D. cough >particularly at night and/or in the early morning.
Asthma classification based on trigger
seasonal exercise-induced drug-induced (e.g., aspirin) occupational asthma asthmatic bronchitis in smokers.
Atopic asthma
-most common type of asthma
-type I hypersensitivity reaction
-childhood onset
-triggered by environmental allergens and viral infections
-positive family history of asthma
-skin test with the offending antigen in these patients results in an immediate wheal and flare reaction
-diagnosis based on
>high total serum IgE levels
>evidence of allergen sensitization by serum radioallergosorbent tests (called RAST), which can detect the presence of IgE antibodies that are specific for individual allergens.
Drug induced asthma
- occurring in individuals with recurrent rhinitis and nasal polyps
- sensitive to small doses of aspirin and NSAIDs
- triggers asthma by inhibiting the COX, leading to a rapid decrease in PGE2, which normally inhibits enzymes that generate LT-B4, C4, D4 and E4, which cause bronchoconstriction
Pathogenesis of asthma
- Increased Th2 response to innocuous stimuli
- Release
A. IL-4: stimulates IgE production
B. IL-5: activates recruited eosinophils
C. IL-13: stimulates mucus secretion and increases IgE production by B cells
D. Chemokines: recruit more T cells - This IgE binds to Fc receptor on submucosal mast cell
- On repeat exposure, it causes degranulation and release of contents of mast cells
- Over time, AIRWAY remodelling
Phases of asthma
1. Early phase A. bronchoconstriction B. increased mucus production C. vasodilation D. increased vascular permeability.
- Late phase-recruitment of leukocytes
A. eosinophils
B. neutrophils
C. More T cells.
T cells involved in asthma
Th2: IL-4,5,13
Th17: IL-17
Recruits neutrophils
Mediators involved in asthma
1. Major
A. LT- C4, D4, E4
B. Acetylcholine
2. Minor
A. Histamine
B. PGD2
C. Platelet activating factor
3. Not yet studied
A. IL-4,5,13
B. IL-1, TNF
C. IL-6
D. Chemokine eg. eotaxin
