Pulmonary
11 high-yield topics. Open a topic to review its pearls.
Pulmonary Function Tests
Obstructive vs restrictive
PFT Patterns
- Obstructive (COPD): low FEV1/FVC, high TLC, high RV
- COPD: low DLCO; Asthma: normal DLCO
- Restrictive (ILD): FEV1/FVC normal, low TLC, low DLCO
- FEV1/FVC under 70 percent = obstructive
DLCO
- Increased: alveolar hemorrhage, polycythemia, CHF
- Decreased: COPD, ILD, PE, pulmonary HTN
- Normal: asthma, extrathoracic restriction
Flow Volume Loops
- Fixed obstruction: both loops flattened (tracheal stenosis)
- Extrathoracic: inspiratory flattening (vocal cord dysfunction)
- Intrathoracic: expiratory flattening (tracheomalacia)
Arterial Blood Gases
Acid-base interpretation
Acidosis/Alkalosis
- Check pH: acidosis under 7.4, alkalosis over 7.4
- Anion gap = Na - (Cl + HCO3), normal 12
- Winters formula: expected pCO2 = 1.5(HCO3) + 8 plus or minus 2
Anion Gap Causes (MUDPILES)
- Methanol, Uremia, DKA, Paraldehyde, INH/Iron, Lactic acidosis, Ethylene glycol, Salicylates
Respiratory Compensation
- Acute respiratory acidosis: pCO2 up 10, pH down 0.08, HCO3 up 1
- Chronic: pCO2 up 10, pH down 0.03, HCO3 up 3
- Metabolic alkalosis: check urine chloride
Asthma
Classification and treatment
Classification
- Mild intermittent: 2 or fewer per week, albuterol PRN
- Mild persistent: over 2 per week, add low-dose inhaled steroids
- Moderate: daily, medium ICS + LABA
- Severe: continual, high ICS + LABA + oral steroids
Special Presentations
- Exercise-induced: inhaled B2-agonist before exercise
- Aspirin-induced: asthma + polyps + ASA sensitivity, leukotriene inhibitors
- ABPA: eosinophilia, IgE to Aspergillus, central bronchiectasis, steroids
- Occupational: peak flow at work vs home
Severe Exacerbation
- Pulsus paradoxus over 15, PCO2 over 40 (ominous), O2 sat under 90
- Hospitalize, IV steroids, nebulized B2-agonists
- Intubate if rising PCO2
COPD
GOLD staging and treatment
GOLD Classification
- FEV1/FVC under 70 percent required
- GOLD I: FEV1 80 or more; short-acting bronchodilator PRN
- GOLD II: 50-80; add tiotropium + rehab
- GOLD III: 30-50; add inhaled corticosteroid
- GOLD IV: under 30; add long-term oxygen
Treatment Points
- Smoking cessation: only measure that changes natural history
- Oxygen: only therapy that improves survival (PaO2 under 55 or sat under 88)
- Tiotropium superior; inhaled steroids decrease exacerbations
- Pulmonary rehab improves tolerance (not survival)
Exacerbations
- Increased dyspnea, sputum volume/purulence
- H. influenzae, Moraxella, S. pneumoniae
- Macrolides or fluoroquinolones (not erythromycin)
- BiPAP before intubation
Interstitial Lung Disease
IPF, sarcoidosis, occupational
Upper vs Lower Zone
- Upper: sarcoidosis, silicosis, berylliosis, ankylosing spondylitis
- Lower: asbestosis, IPF, collagen vascular disease
IPF
- Dry cough, dyspnea, clubbing, honeycombing
- Restrictive PFTs, reduced DLCO, UIP pattern
- No effective treatment; oxygen and transplant
Sarcoidosis
- Non-caseating granulomas, hilar adenopathy
- Increased CD4/CD8 on BAL, elevated ACE
- Stage I: hilar adenopathy (60 percent remit)
- Steroids if symptomatic/worsening PFTs
- Diagnosis: transbronchial biopsy
Occupational Lung Disease
Asbestos, silica, beryllium
Asbestos
- Shipyards, brakes; lower lobe, velcro crackles
- Mesothelioma (no cigarette role); lung cancer (cigarettes multiply)
- Pleural plaques = marker of exposure only
Others
- Silicosis: sandblasting, upper lobe, eggshell calcifications, increased TB
- Berylliosis: aerospace, sarcoid-like, lymphocyte transformation test
- Coal workers: black lung
DVT and Pulmonary Embolism
Diagnosis and treatment
Risk Factors
- Previous DVT = biggest risk
- Virchow triad: stasis, endothelial injury, hypercoagulability
- Factor V Leiden: most common inherited disorder
- Knee replacement 70 percent, hip replacement 50 percent
Diagnosis
- ABG: acute respiratory alkalosis, A-a gradient over 20
- CXR: usually normal; Westermark sign, Hampton hump
- EKG: sinus tachycardia (S1Q3T3 rare)
- Spiral CT chest; gold standard pulmonary angiography
Treatment
- Treat empirically if suspicion high
- Heparin/LMWH bridge to warfarin 3-6 months
- Thrombolytics if hypotension from massive PE
- IVC filter: contraindication to anticoagulation or failure
- Fat embolism (hip fracture) and amniotic fluid embolism: do NOT anticoagulate
Pulmonary Hypertension
Classification and treatment
Definition and Groups
- Mean PA pressure over 25 mmHg at rest
- Group I: PAH (idiopathic, drugs, connective tissue, HIV, portal HTN)
- Group II: left heart disease
- Group III: hypoxic (COPD, ILD, sleep apnea)
- Group IV: chronic thromboembolic
Diagnosis and Treatment
- Echo best screen; right heart cath definitive
- Vasoreactivity testing
- CCB only if proven responders
- Bosentan (endothelin antagonist), sildenafil, epoprostenol
- Anticoagulation if Group 1
Pneumonia
CAP, HAP, VAP
Community-Acquired
- S. pneumoniae most common (rusty sputum)
- Staph aureus: post-influenza, salmon-pink sputum
- Klebsiella: currant jelly sputum, bulging fissure
- Legionella: water sources, diarrhea, hyponatremia, urine antigen
- Mycoplasma: young, bullous myringitis, cold agglutinins
CURB-65
- Confusion, Urea over 19.6, RR over 30, BP low, age over 65
- 0-1 outpatient, 2-3 inpatient, 4-5 ICU
HAP/VAP
- HAP: over 48h after admission
- VAP: over 48h after intubation
- MDR organisms: MRSA, Pseudomonas, Acinetobacter
- Prevention: elevate head of bed 45 degrees
Tuberculosis
Diagnosis, PPD, treatment
Clinical Forms
- Primary: Gohn focus, usually asymptomatic
- Latent: positive PPD, no symptoms, 10 percent lifetime reactivation
- Reactivation: upper lobe/apical, cavitation
- Progressive primary (HIV): lower lobe
- Miliary: hematogenous, reticulonodular
PPD Interpretation
- 5mm or more: HIV, close contacts, transplant, immunosuppressed
- 10mm or more: IV drug users, immigrants, healthcare workers, DM
- 15mm or more: no risk factors
Treatment
- Latent: INH 9 months or rifampin 4 months
- Active: RIPE x2 months, then INH + rifampin x4 months
- Directly observed therapy improves adherence
- HIV: use rifabutin instead of rifampin, DOT mandatory
Cystic Fibrosis and Bronchiectasis
Genetic lung diseases
Cystic Fibrosis
- Autosomal recessive, CFTR gene (deltaF508)
- Recurrent pneumonias (Staph, Pseudomonas)
- Upper zone bronchiectasis, pancreatic insufficiency
- Diagnosis: elevated sweat chloride over 60 x2
- Burkholderia cepacia: contraindication to transplant
Alpha-1 Antitrypsin
- Young non-smoker with COPD, lower zone bullae
- Family history, ZZ homozygous
- IV augmentation therapy
- Kartagener: bronchiectasis + sinusitis + infertility + situs inversus