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System 02 · ~11% of exam

Pulmonary

Dyspnea and cough drive most pulmonary vignettes. The trick: distinguish obstructive (asthma, COPD) from restrictive (fibrosis, neuromuscular) from vascular (PE, pulmonary HTN) from infectious (pneumonia, TB).

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Chief complaints

BUILD THE DIFFERENTIAL

Vignettes enter through one of these doors. Each complaint lays out the full differential, marks the can't-miss diagnoses, and tells you the next right action for each.

Dyspnea (pulmonary)CoughHemoptysis
CHIEF COMPLAINT · HIGH-YIELD

Dyspnea (pulmonary)

Acute vs chronic is the first fork. Then hypoxic vs not.

Approach

Acute: PE, pneumothorax, pulmonary edema, asthma or COPD exacerbation, pneumonia, anaphylaxis, DKA. Chronic: COPD, asthma, ILD, pulmonary HTN, HF, obesity hypoventilation, anemia. The workup pattern: SpO2, CXR, ABG, BNP, D-dimer as indicated.

The differential
Diagnosis Key features / clues Next step
Pulmonary embolism Pleuritic pain, tachycardia, hypoxia, unilateral leg swelling. Risk factors: immobility, malignancy, OCP, pregnancy, prior VTE. Wells → D-dimer if low, CT-PA if intermediate/high · anticoagulate
Tension pneumothorax Sudden, unilateral absent breath sounds, tracheal deviation away, hypotension. Needle decompression 2nd ICS MCL before imaging
Cardiogenic pulmonary edema Orthopnea, bilateral crackles, S3, JVD, edema. Furosemide · O2 · BiPAP · nitrates if hypertensive
Anaphylaxis Rapid onset, stridor, wheezing, urticaria, hypotension after exposure. IM epinephrine 0.3–0.5 mg lateral thigh · repeat Q5 min PRN
Asthma exacerbation Wheezing, prolonged expiration, accessory muscle use, prior asthma history. SABA + ipratropium nebs · systemic steroids · magnesium if severe · intubate if exhausted or silent chest
COPD exacerbation Increased dyspnea, cough, sputum purulence in known COPD. SABA/SAMA · steroids (prednisone 40 mg × 5 days) · antibiotics if ≥ 2 cardinal features
Pneumonia Fever, productive cough, focal crackles, consolidation on CXR. CURB-65 or PSI for disposition · empiric antibiotics
⚑ = can't-miss diagnosis · rule out first
Classic vignette
Exam-style stem
A 34-year-old woman on oral contraceptives presents with 2 hours of dyspnea and sharp right-sided chest pain, pleuritic. HR 108, RR 24, SpO2 92% on room air. CXR is clear. D-dimer 2800.
Next step?
Answer › CT-PA. Wells score is likely intermediate to high. The positive D-dimer in this setting is expected, it cannot rule out. Treat empirically with heparin while awaiting imaging if high clinical suspicion and no contraindications.
Pearls
Pearl
The classic ECG finding in PE is sinus tachycardia, not the S1Q3T3 you memorized. S1Q3T3 is specific but insensitive.
Pearl
Hypoxia that corrects easily with supplemental O2 is V/Q mismatch (most things). Hypoxia that doesn't correct is shunt (ARDS, atelectasis, intracardiac shunt).
Pearl
A-a gradient: elevated in V/Q mismatch, shunt, diffusion impairment. Normal in hypoventilation (CNS depression, opioids) and high altitude.
CHIEF COMPLAINT · HIGH-YIELD

Cough

Duration splits the differential: acute (< 3 wk), subacute (3–8 wk), chronic (> 8 wk).

Approach

Acute: URI, bronchitis, pneumonia, PE, heart failure. Subacute: post-infectious, pertussis. Chronic: the big three are upper airway cough syndrome (postnasal drip), asthma, and GERD. Also consider ACEi, smoking, bronchiectasis, TB, lung cancer, and ILD.

The differential
Diagnosis Key features / clues Next step
Community-acquired pneumonia Fever, productive cough, consolidation on CXR. CURB-65 · outpatient: amoxicillin or doxycycline · inpatient: ceftriaxone + azithromycin
Lung cancer Smoker > 20 pack-years, chronic cough, hemoptysis, weight loss. CXR → CT chest · biopsy
Tuberculosis Chronic cough, hemoptysis, night sweats, weight loss, TB exposure or endemic country. AFB smear × 3, sputum culture, NAAT · CXR (upper lobe cavitary) · isolate
Upper airway cough syndrome Postnasal drip, throat clearing, cobblestoning. First-generation antihistamine trial
Asthma / cough-variant Nocturnal cough, wheezing, atopy, diurnal variation. Spirometry with bronchodilator response · methacholine challenge if normal
GERD Postprandial, nocturnal, heartburn may or may not be present. Empiric PPI × 8 weeks
ACE inhibitor cough Dry cough developing weeks to months after starting ACEi. Switch to ARB
⚑ = can't-miss diagnosis · rule out first
Classic vignette
Exam-style stem
A 67-year-old man with a 45 pack-year smoking history has had a cough for 4 months, with 10 pounds of weight loss and two episodes of hemoptysis.
Best next step?
Answer › CT chest. CXR first by convention, but low-dose CT is the screening and workup modality for suspected lung cancer. He meets USPSTF criteria for lung cancer screening (age 50–80, ≥ 20 pack-years, current smoker or quit within 15 years).
Pearls
Pearl
Three causes account for 90% of chronic cough in non-smokers with a normal CXR: upper airway cough syndrome, asthma, GERD. Treat them sequentially if the diagnosis is unclear.
Pearl
An ACEi cough can start months after initiation. Always ask about medications in chronic cough.
Pearl
Hemoptysis plus smoker plus weight loss means CT chest, not another antibiotic course.
CHIEF COMPLAINT

Hemoptysis

Massive (> 600 mL/24h) kills by asphyxiation, not exsanguination. Position bleeding side down.

Approach

The big differential: bronchitis, bronchiectasis, TB, lung cancer, PE with infarction, vasculitis (GPA, anti-GBM), pulmonary edema (pink frothy). Always confirm it's truly pulmonary (not GI or nasopharyngeal).

The differential
Diagnosis Key features / clues Next step
Massive hemoptysis > 600 mL/24h or hemodynamically unstable. Protect airway (intubate if needed) · position bleeding side DOWN · bronchoscopy · embolization
Lung cancer Smoker, weight loss, chronic cough. CT chest · biopsy
Tuberculosis Night sweats, weight loss, exposure. AFB × 3 · isolate
PE with infarction Pleuritic pain, VTE risk factors, often small-volume hemoptysis. CT-PA
Bronchiectasis Chronic purulent sputum, recurrent infections, clubbing, cystic changes on CT. CT chest · sputum culture · antibiotics
Goodpasture / GPA Hemoptysis + hematuria + pulmonary-renal syndrome. Anti-GBM, ANCA · renal biopsy · plasmapheresis + steroids + cyclophosphamide
⚑ = can't-miss diagnosis · rule out first
Pearls
Pearl
Always rule out the mimics: epistaxis with posterior drainage and hematemesis can look like hemoptysis. Frothy red sputum is pulmonary; coffee-ground or with food is GI.
Pearl
Massive hemoptysis kills by drowning, not bleeding. Intubate if necessary to protect the good lung. Put the bleeding side down so blood doesn't flood the contralateral lung.
✦

Disease deep dives

DEFINITIVE DX

Once you've identified the likely diagnosis from the chief complaint, these pages give you the presentation, workup, management, and exam pearls in depth.

Asthma
Reversible airway obstruction. Step therapy from SABA alone to biologics. Exacerbation management is the exam's favorite.
COPD
Irreversible obstruction from smoking (usually). The workhorse: staging, exacerbation, and when to give oxygen.
Pulmonary Embolism
Clot in the pulmonary artery. Diagnosis is about pretest probability. Treatment tiers by hemodynamic stability.
Pneumonia
CAP vs HAP vs VAP vs aspiration. Pathogen and severity drive antibiotic choice and disposition.
DISEASE DEEP DIVE

Asthma

Reversible airway obstruction. Step therapy from SABA alone to biologics. Exacerbation management is the exam's favorite.

Presentation

Episodic wheeze, cough, dyspnea, chest tightness. Triggers: allergens, cold, exercise, URI, aspirin. Atopic history common.

Workup
  1. Spirometry. FEV1/FVC < 0.7 with ≥ 12% improvement after bronchodilator is diagnostic.
  2. Methacholine challenge. If spirometry is normal but clinical suspicion remains. > 20% FEV1 drop is positive.
  3. Peak flow. For monitoring, not diagnosis.
  4. FeNO. Elevated in eosinophilic asthma, useful to identify biologic candidates.
Management
  1. Step 1, intermittent. PRN ICS-formoterol (preferred, GINA) or SABA PRN.
  2. Step 2, mild persistent. Low-dose ICS + PRN SABA, OR ICS-formoterol as needed.
  3. Steps 3–4, moderate. Low-to-medium dose ICS + LABA, as maintenance and reliever therapy (MART).
  4. Step 5, severe. High-dose ICS-LABA + tiotropium or biologic. Biologic choice by phenotype: anti-IgE (omalizumab), anti-IL-5 (mepolizumab, benralizumab), anti-IL-4R (dupilumab).
  5. Exacerbation. Albuterol + ipratropium nebs Q20 min × 3, oral or IV steroids, O2 to SpO2 ≥ 92%. IV magnesium if severe. Intubate for silent chest, altered mental status, rising CO2.
Pearls
Pearl
A normalizing CO2 in a severe asthma attack is ominous, not reassuring. It means the patient is tiring.
Pearl
Aspirin-exacerbated respiratory disease (Samter triad): asthma, nasal polyps, NSAID sensitivity. Treat with leukotriene inhibitors and aspirin desensitization.
Pearl
Occupational asthma: symptoms improve on weekends and vacations. Common exposures: bakers (flour), painters (isocyanates), healthcare (latex).
Classic vignette
Exam-style stem
A 22-year-old man with asthma presents in respiratory distress. Speaking in 2-word phrases, using accessory muscles. No wheezing heard. SpO2 89%.
Answer › Silent chest with respiratory distress is impending respiratory failure. Continuous nebulizers, IV steroids, IV magnesium, prepare to intubate.
DISEASE DEEP DIVE

COPD

Irreversible obstruction from smoking (usually). The workhorse: staging, exacerbation, and when to give oxygen.

Presentation

Chronic cough, sputum, dyspnea. Smoker > 20 pack-years. Barrel chest, pursed-lip breathing, decreased breath sounds, prolonged expiration.

Workup
  1. Spirometry. Post-bronchodilator FEV1/FVC < 0.7 is diagnostic.
  2. GOLD staging. GOLD 1 (FEV1 ≥ 80%), 2 (50–79%), 3 (30–49%), 4 (< 30%). Symptoms and exacerbation history now drive therapy (ABE groups).
  3. Alpha-1 antitrypsin. If young, non-smoker, or basilar emphysema.
Management
  1. All patients. Smoking cessation (only intervention that slows progression), vaccines (flu, pneumococcal, COVID, RSV, Tdap), pulmonary rehab.
  2. Group A (low sx, low risk). Bronchodilator (LABA or LAMA).
  3. Group B (high sx, low risk). LABA + LAMA.
  4. Group E (high exacerbation). LABA + LAMA ± ICS (ICS if eosinophils ≥ 300 or asthma overlap).
  5. Long-term oxygen. PaO2 ≤ 55 or SaO2 ≤ 88% at rest, OR ≤ 59/89 with cor pulmonale or polycythemia. The only intervention besides cessation that improves survival.
  6. Exacerbation. Short-acting bronchodilators, oral or IV steroids (prednisone 40 mg × 5 days), antibiotics if ≥ 2 of increased dyspnea, sputum volume, or purulence. BiPAP if pH < 7.35 and PCO2 > 45.
Pearls
Pearl
Two interventions reduce mortality in COPD: smoking cessation and continuous oxygen in qualifying patients. Nothing else.
Pearl
Do not be afraid to give oxygen to a COPD patient who needs it. The CO2 retention risk is real but modest, and hypoxia kills faster.
Pearl
Beta-blockers are safe in COPD. Cardioselective agents (metoprolol, bisoprolol) are indicated if there is a cardiac reason.
Classic vignette
Exam-style stem
A 68-year-old smoker with COPD has worsening dyspnea, increased sputum purulence, and more frequent puffer use for 4 days. RR 24, SpO2 89% on RA. ABG: pH 7.33, PCO2 52.
Answer › Moderate exacerbation with respiratory acidosis. Bronchodilators, prednisone 40 mg × 5 days, azithromycin or doxycycline, BiPAP given pH < 7.35 and hypercapnia.
DISEASE DEEP DIVE

Pulmonary Embolism

Clot in the pulmonary artery. Diagnosis is about pretest probability. Treatment tiers by hemodynamic stability.

Presentation

Dyspnea, pleuritic pain, tachycardia, hypoxia. Risk factors: immobility, malignancy, pregnancy, OCPs, prior VTE, inherited thrombophilia, recent surgery.

Workup
  1. Wells score. PE likely (> 4) vs unlikely (≤ 4). Drives next step.
  2. D-dimer. Only useful if Wells ≤ 4 and no other high-risk features. Age-adjusted cutoff: age × 10 in patients > 50 years.
  3. CT-PA. First-line imaging. Sensitive and specific.
  4. V/Q scan. If CT contrast is contraindicated (pregnancy, severe renal dysfunction, contrast anaphylaxis).
  5. Echo. For risk stratification. RV strain predicts mortality.
Management
  1. Massive PE (hemodynamic instability). Systemic thrombolysis (tPA 100 mg over 2 hours). Surgical or catheter embolectomy if thrombolytics are contraindicated.
  2. Submassive (RV dysfunction, elevated troponin, stable BP). Heparin. Consider catheter-directed thrombolysis.
  3. Low-risk PE. DOAC (apixaban or rivaroxaban) as outpatient if feasible.
  4. Duration. Provoked by transient factor: 3 months. Unprovoked or malignancy: indefinite. Consider thrombophilia workup only if it would change management.
  5. IVC filter. Only if anticoagulation is contraindicated or there is recurrent PE despite adequate anticoagulation.
Pearls
Pearl
In pregnancy, CT-PA and V/Q are both acceptable. Bilateral lower extremity ultrasound first if leg symptoms are present (no radiation).
Pearl
Saddle embolus is a CT finding, not a severity classifier. A saddle embolus in a stable patient is still anticoagulation only.
Pearl
Submassive PE with RV strain is the trickiest category. The current trend is catheter-directed thrombolysis over systemic.
Classic vignette
Exam-style stem
A 45-year-old woman, 5 days post-op hysterectomy, with dyspnea and tachycardia. BP 90/60, HR 120, SpO2 88%. CT-PA: large bilateral PE with RV strain.
Answer › Massive PE. Systemic thrombolysis (tPA) if no contraindications. If contraindicated, catheter embolectomy or ECMO.
DISEASE DEEP DIVE

Pneumonia

CAP vs HAP vs VAP vs aspiration. Pathogen and severity drive antibiotic choice and disposition.

Presentation

Fever, productive cough, pleuritic pain, dyspnea. Exam: focal crackles, bronchial breath sounds, egophony, dullness to percussion. CXR shows infiltrate.

Workup
  1. CXR. Lobar (bacterial, Strep pneumo), interstitial (viral, atypical), cavitary (TB, Staph, anaerobes, fungal).
  2. CURB-65. Confusion, Urea > 20, RR ≥ 30, BP < 90/60, age ≥ 65. Outpatient 0–1, inpatient 2, ICU ≥ 3.
  3. Blood cultures. Before antibiotics if hospitalized.
  4. Sputum Gram stain and culture. If severe or suspected resistant pathogen.
  5. Urinary antigen. Strep pneumo, Legionella (if severe).
Management
  1. CAP outpatient, healthy. Amoxicillin, doxycycline, or macrolide (resistance limits macrolides).
  2. CAP outpatient, comorbidities. Amox-clav or cefpodoxime PLUS macrolide or doxycycline, OR respiratory fluoroquinolone (levofloxacin, moxifloxacin).
  3. CAP inpatient, non-ICU. Ceftriaxone + azithromycin, OR respiratory fluoroquinolone.
  4. CAP ICU. Ceftriaxone + azithromycin. Add anti-MRSA and anti-pseudomonal coverage if risk factors are present.
  5. HAP/VAP. Broad-spectrum: pip-tazo or cefepime + vancomycin. Tailor to local antibiogram.
  6. Aspiration. Ampicillin-sulbactam or clindamycin (anaerobic coverage). RLL if upright; posterior segment of upper lobe or superior segment of lower lobe if supine.
Pearls
Pearl
Legionella: GI symptoms (diarrhea), hyponatremia, relative bradycardia, exposure to water systems. Urine antigen only detects serogroup 1.
Pearl
Mycoplasma: young patient, insidious, dry cough, bullous myringitis, cold agglutinins. The walking pneumonia.
Pearl
Not improving after 72 hours of antibiotics: wrong bug, wrong antibiotic, complication (empyema, abscess), or wrong diagnosis (malignancy, PE, vasculitis).
Classic vignette
Exam-style stem
A 72-year-old nursing home resident with altered mental status, fever, and productive cough. BP 92/58, HR 110, RR 32, BUN 35, confusion.
Answer › CURB-65 = 4. ICU. Cover for healthcare-associated pneumonia: vancomycin + pip-tazo (or cefepime + vancomycin) until cultures return.
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