Pulmonary Flashcards
Allergic Bronchopulmonary Aspergillosis (ABPA)
Path
Prevalence
Path:
- Aspergillus fumigatus-> 80% of clinical infections
- Lung disease from hypersensitivity to aspergillus species caused by impaired mucociliary clearance, mucoid impaction, and airway obstruction
- Maybe due to increased use of antibiotics for infective exacerbations promoting the growth of fungal infections
Prevalence: 6-25% in CF patients; 1-8% in asthmatics Increased in: -Children >6y/o -Adolescents -Pts w/ decreased lung function -Chronic infection w/ (positive association of ABPA and P aeruginosa and S maltophilia) **P aeruginosa **Burkholderia cepacia **Stenotrophomonas **Candida albicans
Fungal pulmonary infection suspected for:
- CF, asthma
- Pre-existing lung cavities
- Severely immunocompromised
CF, asthma: Allergic bronchopulmonary aspergillosis
Pre-existing lung cavities:
- Aspergilloma
- Chronic necrotizing aspergillosis
Severely immunocompromised: Invasive aspergillosis
ABPA Sx and PE
Sx: worsening/new onset wheeze, dyspnea, fevers, chest pain, cough, hemoptysis, malaise, expectoration of brown/black mucous plugs, can be asx
High suspicion if pt fails to respond to IV abx for chest sx
PE: normal-non-specific: wheezes/crackles
ABPA Staging
Stage 1 (acute stage):
- acute wheeze, reversible airway obstruction
- markedly elevated IgE
- peripheral eosinophilia
- IgE and IgG to A fumigatus
- pulmonary infiltrates
Stage 2 (remission stage):
- decrease in IgE but NOT to normal
- Absence of eosinophilia
- Resolution of pulmonary infiltrates
Stage 3 (exacerbation stage): -Pts with known ABPA, similar to stage 1
Stage 4 (corticosteroid-dependent stage): -Steroid dependent, attempt to reduce/stop steroids leads to worsening ABPA w/ evidence of central bronchiectasis on CT
Stage 5 (fibrotic stage):
- Ends stage respiratory failure
- Serum IgE high/low
- Eosinophil count high/low
Screening for ABPA
High level of suspicion for ABPA in pts >6y/o
Measure serum IgE annually
- > 500 IU/ml: determine immediate cutaneous reactivity to A fumigatus and consider diagnosis
- 200-500 IU/ml: repeat IgE level and perform further diagnostic tests
ABPA Dx
Acute/subacute clinical deterioration
Serum total IgE > 1,000 IU/ml (major criteria for dx ABPA)
-RAST testing or Immediate cutaneous reactivity to A fumigatus >3mm or raised specific IgE to A fumigatus
Precipitating IgG antibodies to A fumigatus
Blood eosinophil count (Maybe present in CF due to chronic P aeruginosa infection rather than ABPA; may represent previous exposure rather than current disease)
New/recent changes on CXR/chest CT
`CXR:
-Transient-persistent pulmonary infiltrations in upper/mid lobes
-Clearing of infiltrates, partially/completely w/ oral steroids maybe suggestive of ABPA
Chest CT:
-Central bronchiectasis hallmark of ABPA (vs cylindrical bronchiectasis more common in CF)
-Varicose and cystic bronchiectasis typical in ABPA
-Single or multiple nodules with/without cavitation, patchy or segmental consolidation, peribronchial infiltrates with/without tree in bud patterns
Mere presence of A fumigatus isolated in sputum of CF is NOT associated with ABPA (seen in 9-57% of CF pts) or with worsening lung function
Marker used for ABPA exacerbation or measure response to therapy
A fumigatus serum total IgE
ABPA cutaneous reactivity testing False + False - Sensitivity Specificity
False +: Pts with severe eczema
False -: Taking antihistamines 24-48 hrs
High sensitivity-> absence of reaction reduces likelihood of ABPA (rule out ABPA)
Moderately low specificity (23-28% asthmatics; 29% CF)-> will have + skin test without ABPA (false positive)
RAST testing preferred over skin testing
ABPA Tx
Steroids (1st line)
- 2 weeks of daily oral prednisone (1-2mg/kg) followed by gradual tapering with duration of tx of at least 3 months
- Has been recommended for new ABPA infiltrates
Monitor serum IgE levels
- useful parameter of disease control
- Reduction of 30-50% is expected w/ commencement of therapy
Antifungal therapy
- Itraconazole (1st line), broad spectrum
- Voriconazole: newer drug, better tolerance and bioavailability
Obstructive disease Path: Dz: Flow Volume Loop: PFT:
Path: limits expiration
Dz:
- Asthma
- Bronchiectasis
- CF
Flow Volume Loop:
- Scooped flow volume loop
- Inc TLC, RV
- Dec/normal VC
PFT:
FEV1: Dec
FVC: Dec/normal
FEV1/FVC: Dec
Restrictive disease Path: Dz: Flow Volume Loop: PFT:
Path: limits inspiration
Dz:
- Neuromuscular disease
- Scoliosis
- Interstitial lung disease
- Obesity
Flow Volume Loop:
- Small
- Dec TLC, RV, and VC
PFT:
FEV1: Dec/normal
FVC: Dec
FEV1/FVC: Normal/Inc
Name the lung volumes
Inspiratory reserve volume (IRV)
Tidal volume (Vt)
Expiratory reserve volume (ERV)
Residual volume (RV)
Define vital capacity
Functional residual capacity
IRV + Vt + ERV
Total volume of air that can be exhaled after maximum inspiration
Define FRC
ERV + RV
Amount of air remaining in lungs after normal expiration
Define FVC
Forced vital capacity
Amount of air exhaled forcefully and quickly after maximum inspiration
Define FEV
Forced expiratory volume
Volume of air expired during the first, second, and third seconds of the FVC test
Define FEF
Forced expiratory flow
Average rate of flow during the middle half of the FVC test
Mix PFT results
FEV1: Dec
FVC: Dec
FEV1/FVC: Dev
FEV1 severity
FEV1 > 80% -> normal
FEV1 <85-60% -> mild severity
FEV1 <60-40% -> moderate severity
FEV1 <40 -> severe severity
How to interpret a PFT
FEV1 >80, normal
FEV1 <80 (restrictive or obstructive), look at FVC and FEV1/FVC ratio
FEV1/FVC ratio <80 -> Obstructive
FEV1/FVC ratio >/=80 w. Low FEV1 -> restrictive
