Shortness of breath is among the most frequently tested CCS presentations on Step 3, and it has the widest differential of any chief complaint. The challenge is not knowing what SOB can be — it is efficiently narrowing the differential, ordering the right tests in the right sequence, and initiating treatment without delay. This article gives you the complete approach.
The First 60 Seconds: Every SOB Case
Immediate orders (before physical exam if any vital sign is abnormal):
1. Pulse oximetry
2. Supplemental oxygen (nasal cannula or non-rebreather depending on severity)
3. IV access
4. Cardiac monitor
5. Fingerstick glucose (rule out metabolic cause)
Then perform: Focused physical exam — pulmonary and cardiac systems at minimum.
Listen for the key exam findings that narrow your differential:
• Crackles/rales → CHF, pneumonia, pulmonary fibrosis
• Wheezing → Asthma, COPD exacerbation, anaphylaxis
• Decreased breath sounds → Pneumothorax, pleural effusion, COPD
• JVD + peripheral edema → CHF, cardiac tamponade
• Stridor → Upper airway obstruction (anaphylaxis, foreign body, epiglottitis)
Stat labs:
• CBC (infection, anemia)
• BMP (metabolic acidosis, renal failure)
• Troponin (cardiac cause)
• BNP or NT-proBNP (heart failure vs. pulmonary cause)
• ABG or VBG (assess oxygenation and acid-base status)
• D-dimer (if PE is on differential and patient is low/moderate risk)
Initial imaging:
• Chest X-ray (the single most informative initial test for SOB)
• EKG (rule out cardiac cause, right heart strain pattern for PE)
Advance the clock 15–30 minutes to get initial results.
Branch Point: CXR + Labs Guide Your Next Move
Branch 1: Pulmonary Edema on CXR + Elevated BNP → CHF Exacerbation
Management:
• Furosemide IV (diuresis is first-line)
• Nitroglycerin (if hypertensive)
• Oxygen (titrate to SpO2 > 94%)
• Morphine (use sparingly; reserved for refractory cases)
• ACE inhibitor (once stabilized)
• Echocardiogram
• Strict I&Os, daily weights
• Sodium restriction, fluid restriction
• Cardiology consult if new diagnosis
Monitoring:
• Repeat CXR in 24 hours
• Daily BMP (monitor potassium and creatinine with diuretics)
• Daily weights
• Repeat BNP to track response
Disposition: ICU if requiring BiPAP/intubation or hemodynamically unstable. Floor if stable on oxygen. Discharge when euvolemic with outpatient follow-up in 1 week.
Branch 2: Infiltrate on CXR + Fever + Elevated WBC → Pneumonia
Management:
• Blood cultures x 2 (BEFORE antibiotics)
• Sputum culture and gram stain
• Advance clock 1 minute after cultures, THEN antibiotics
• Antibiotics: community-acquired → ceftriaxone + azithromycin; hospital-acquired → broad-spectrum (piperacillin-tazobactam or meropenem + vancomycin)
• Legionella urine antigen, pneumococcal urine antigen
• Oxygen support as needed
• IV fluids if dehydrated
Monitoring:
• Repeat CXR in 48–72 hours
• Follow fever curve, WBC trend
• Repeat cultures if not improving
Disposition: Floor for most community-acquired pneumonia. ICU if septic, requiring vasopressors, or needing mechanical ventilation. Discharge when afebrile for 48 hours, improving, and tolerating oral antibiotics.
Branch 3: Clear CXR + Tachycardia + Risk Factors → Pulmonary Embolism
If low/moderate pretest probability:
• D-dimer → if elevated, proceed to CT pulmonary angiography (CTPA)
If high pretest probability:
• Skip D-dimer, go directly to CTPA
• Start empiric heparin while awaiting imaging
PE confirmed on CTPA:
• Heparin drip (or enoxaparin)
• Transition to oral anticoagulation (warfarin, rivaroxaban, or apixaban)
• Lower extremity Doppler ultrasound (look for DVT source)
• Echocardiogram (assess right heart strain)
• If massive PE with hemodynamic instability: thrombolytics (alteplase) + ICU transfer
• Pulmonology or hematology consult
Monitoring:
• Serial vitals (watch for hemodynamic instability)
• Repeat troponin (right heart strain marker)
• INR monitoring if on warfarin
Branch 4: Wheezing + History of Asthma/COPD → Exacerbation
Asthma exacerbation:
• Albuterol nebulizer (continuous or Q20min)
• Ipratropium nebulizer
• Systemic corticosteroids (methylprednisolone IV or prednisone PO)
• Oxygen
• Peak flow measurement
• Magnesium sulfate IV (if severe)
• If not responding: consider epinephrine, BiPAP, or intubation
COPD exacerbation:
• Albuterol + ipratropium nebulizers
• Systemic corticosteroids
• Antibiotics (azithromycin or levofloxacin — many COPD exacerbations have an infectious trigger)
• Oxygen (target SpO2 88–92% — avoid over-oxygenation in CO2 retainers)
• ABG (monitor for hypercapnia)
• BiPAP if worsening respiratory failure
• Intubation if BiPAP fails
Monitoring:
• Repeat peak flow (asthma)
• Repeat ABG (COPD)
• Continuous pulse oximetry
Branch 5: Absent Breath Sounds + Hypotension → Tension Pneumothorax
Immediate treatment (do not wait for CXR):
• Needle decompression (emergent)
• Chest tube insertion
• Transfer to ICU
• Stat portable CXR (to confirm and assess)
Branch 6: Pleural Effusion on CXR
• Thoracentesis (diagnostic and therapeutic)
• Send pleural fluid for: cell count, glucose, protein, LDH, pH, gram stain, culture, cytology
• Compare pleural fluid to serum (Light's criteria: transudative vs. exudative)
• Manage underlying cause
Don't-Miss Diagnoses for SOB
1. Pulmonary embolism — Always on the differential for acute SOB with clear lungs
2. Tension pneumothorax — Absent breath sounds + hemodynamic instability = act NOW
3. Anaphylaxis — Stridor + wheezing + hypotension → epinephrine IM immediately
4. Cardiac tamponade — JVD + muffled heart sounds + hypotension → pericardiocentesis
5. Acute MI presenting as SOB — Especially in diabetics and elderly who may not have classic chest pain
The Complete Order Set: SOB (ER)
Immediate:
• Pulse oximetry, O2 supplementation
• IV access, cardiac monitor
• Focused PE (cardiac, pulmonary)
Labs:
• CBC, BMP, troponin, BNP, ABG
• D-dimer (if PE suspected)
• Blood cultures (if infection suspected)
• Procalcitonin (if unclear infectious vs. non-infectious)
Imaging:
• CXR (portable)
• EKG
• CTPA (if PE suspected)
• Echocardiogram (if CHF, tamponade, or PE with right heart strain)
Treatment (condition-specific):
• CHF: furosemide, nitroglycerin, ACE inhibitor
• Pneumonia: cultures → antibiotics
• PE: heparin → oral anticoagulation
• Asthma/COPD: nebulizers, steroids
• Pneumothorax: chest tube
Disposition and Follow-up:
• Follow-up appointment
• Smoking cessation counseling
• Pneumococcal and influenza vaccines
• Pulmonary rehabilitation referral (COPD)
• Anticoagulation clinic referral (PE)
Related Chief Complaint Articles:
• CCS Chest Pain: Orders, Algorithms & Don't-Miss Diagnoses
• CCS Abdominal Pain: Step-by-Step Workup & Management
• CCS Altered Mental Status: First 60 Seconds to Disposition
• CCS Fever & Sepsis: Rapid Workup, Orders & Escalation
• Ultimate Guide to CCS Section of Step 3 (2026)