Respiratory confusion pairs
18 Respiratory topics students commonly mix up on Step 2 CK, each with the fastest separator, a side-by-side comparison, and a free practice question.
Step 2 CK pairs are in open beta while clinical review finishes. Spot an issue? Tell us.
- Pulmonary hypertension Group 1 vs Pulmonary hypertension Groups 2-5Pulmonary artery wedge pressure above versus at or below 15 mm Hg on right-heart catheterization is the first branch point.
- OSA vs Central sleep apneaPresence or absence of respiratory effort during apneic events is the primary discriminator.
- Pleural effusion transudate vs Pleural effusion exudateAt least one positive Light criterion.
- Aspiration pneumonia vs Aspiration pneumonitisTiming after aspiration event, hours for chemical injury versus delayed infectious progression.
- Atypical pneumonia organisms vs Typical pneumonia organismsLobar air-space consolidation on chest x-ray favors typical bacterial pneumonia.
- Community-acquired pneumonia vs Hospital-acquired pneumoniaPneumonia onset 48 hours or more after hospital admission defines hospital-acquired pneumonia.
- Obstructive lung disease vs Restrictive lung diseaseThe first branch point is post-bronchodilator FEV1/FVC, because a ratio below 0.70 indicates obstruction.
- COPD exacerbation vs Asthma exacerbationPost-bronchodilator reversibility of FEV1 at least 12% and 200 mL favors asthma over COPD.
- Acute bronchitis vs PneumoniaA new focal infiltrate on chest radiograph identifies pneumonia.
- ARDS vs Cardiogenic pulmonary edemaPulmonary capillary wedge pressure above 18 mm Hg points to cardiogenic pulmonary edema rather than ARDS.
- Pulmonary embolism management low-risk vs Pulmonary embolism management high-riskSustained systolic blood pressure below 90 mm Hg is the immediate branch point to high-risk PE reperfusion management.
- Tuberculosis treatment active vs Tuberculosis treatment latentEvidence of active pulmonary disease on symptoms plus positive sputum testing separates active TB treatment from latent TB treatment.
- Asthma severity classification vs Asthma exacerbation severityCurrent PEF below 50 percent predicted during symptoms identifies a severe exacerbation that requires acute escalation now.
- Tuberculosis active vs Tuberculosis latentSymptoms plus abnormal chest imaging with positive sputum microbiology defines active tuberculosis and separates it from latent infection.
- Idiopathic pulmonary fibrosis vs Hypersensitivity pneumonitisClear antigen exposure history with BAL lymphocytosis favors hypersensitivity pneumonitis over idiopathic pulmonary fibrosis.
- Sarcoidosis vs BerylliosisPositive beryllium exposure history with beryllium lymphocyte proliferation testing distinguishes berylliosis from sarcoidosis.
- Solitary pulmonary nodule benign vs Solitary pulmonary nodule malignantDocumented growth on interval chest CT is the key malignancy discriminator.
- Lobar pneumonia vs BronchopneumoniaChest radiograph pattern of single-lobe dense consolidation versus multifocal patchy infiltrates separates these entities quickly.