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Shortness of Breath

Lungs, heart, blood, blood-gases, or plumbing?

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Your objective: explain the approach, recognize important warning signs, then test your recall.

Abbreviations explained
ACS
Acute coronary syndrome
OMI
Occlusion myocardial infarction
ECG
Electrocardiogram
PE
Pulmonary embolism
POCUS
Point-of-care ultrasound
QTc
QT interval corrected for heart rate
LBBB
Left bundle branch block
RBBB
Right bundle branch block
hs-cTn
High-sensitivity cardiac troponin
CTA
Computed tomography angiography
ICU
Intensive care unit
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The jobLungs, heart, blood, blood-gases, or plumbing?

  1. Separate hypoxemic vs hypercapnic vs non-pulmonary drivers.
  2. POCUS: B-lines, lung sliding, RV size — plus a focused history.
  3. Gate PE (PERC if very-low gestalt; otherwise a validated Wells/age-adjusted or YEARS D-dimer pathway).
  4. Work of breathing decides urgency: silent chest or a “normalising” CO₂ is pre-arrest.

Dyspnea is a symptom, not a diagnosis.

Rapidly separate hypoxemic vs hypercapnic vs non-pulmonary drivers. Bedside ultrasound (B-lines, lung sliding, RV dilatation) plus a focused history resolves most cases faster than any single test.

Pulmonary embolism Critical

Key: Sudden dyspnea with clear lungs; PERC if very-low gestalt, otherwise a validated Wells/age-adjusted or YEARS D-dimer pathway. Echo may show RV strain.

Tension pneumothorax Critical

Key: Trauma, COPD or PPV + hemodynamic collapse → decompress before imaging.

Acute pulmonary edema / LV failure Critical

Key: Orthopnea, crackles, diffuse B-lines — early NIV + nitrates if hypertensive.

Near-fatal asthma / COPD exacerbation Critical

Key: Silent chest, normalizing CO₂, exhaustion = pre-arrest physiology.

Anaphylaxis Critical

Key: IM epinephrine into the anterolateral thigh immediately — do not wait for urticaria (it may be absent).

Carbon monoxide poisoning Critical

Key: Headache, whole household ill; standard SpO₂ is falsely normal — CO-oximetry.

Metabolic acidosis (Kussmaul breathing) Emergent

Key: DKA, sepsis, salicylates, uremia — lungs compensating for the blood.

Neuromuscular weakness (GBS, myasthenia) Emergent

Key: Orthopnea, weak cough, falling NIF/VC — monitor before the crash.

Pneumonia / COPD exacerbation / anemia Common

Key: High-frequency drivers; treat and reassess objectively.

Tick what your patient has — the banner updates as you go.

Tempo

seconds (PE/PTX), minutes (asthma/edema), hours–days (pneumonia/HF), weeks (anemia/effusion)

Positional

orthopnea & PND → LV failure; platypnea → shunt

Exposures

smoke, allergens, occupational, CO source, diving

Background

asthma/COPD, HF, VTE risks, immunosuppression

Associated chest pain, fever, leg swelling, hemoptysis

Work of breathing

accessory muscles, tripod posture, speech in words vs sentences

Stridor (upper airway), wheeze (airway), crackles (alveolar), absent sounds (PTX/effusion)

JVP, edema, S3 → congestion

Cyanosis, agitation, drowsiness = objective severity

POCUS

anterior B-lines, sliding, effusions, RV/LV ratio

Bedside

  • SpO₂ + observation; peak flow in asthma if the patient can perform it
  • POCUS + ECG (RV strain, ischemia)
  • VBG/ABG when hypercapnia or deterioration is suspected

Labs

  • BNP/NT-proBNP, troponin, gated D-dimer (age-adjusted or YEARS), CBC, BMP, lactate
  • CO-oximetry if exposure suspected

Imaging

  • CXR first-line; CTPA when the PE pathway is positive
  • Echo for systolic dysfunction or suspected high-risk PE
Medication safety reminder

Use this as a first-pass prompt; verify all medications, doses, concentrations, contraindications, weight, pregnancy status, and local protocols before administration.

Check indication, allergy, route, renal/hepatic risk, interactions, monitoring, and local formulary.

Discharge

  • Asthma/COPD back to baseline, room-air saturations acceptable, reliable follow-up. Asthma: prescribe an ICS-containing regimen — GINA 2026 does not recommend SABA-only therapy at any step.

Admit (ward / HDU)

  • Persistent hypoxia on therapy, moderate exacerbation, PE or pneumonia requiring inpatient therapy; selected low-risk PE can be treated at home after Hestia/PESI-based assessment, bleeding-risk and follow-up checks; use PSI plus clinical judgment for pneumonia.

ICU / NIV-ventilation

  • NIV failure or exhaustion; COPD with pH <7.25 or falling despite NIV; tension physiology; high-risk PE (shock/hypotension) — PERT/reperfusion, not RV strain alone.

Use objective reassessment and the local pathway.

Before the next decision · reassess and hand over

Use these learning prompts with the presentation’s pathway. They are not discharge criteria.

  1. Reassess: compare symptoms, observations and examination with the initial assessment and response to treatment.
  2. Warning signs for Shortness of Breath:
    • Silent chest, exhaustion, or falling respiratory rate in asthma/COPD
    • Rising CO₂ or falling pH on VBG
    • SpO₂ <90% despite high-flow oxygen
    • Hemodynamic instability or stridor at rest
    • Absent lung sliding with shock
    • New confusion or drowsiness (CO₂ narcosis)
  3. Reconsider: check unresolved findings and alternative explanations, including the pitfalls below.
  4. Escalate: communicate deterioration, uncertainty or needs beyond the current setting.
  5. Plan the transition: identify outstanding results, responsibility for follow-up, patient understanding and specific return advice.
Review this presentation’s disposition pathway →Practice a handover →

Clinical Pearls

  • POCUS (B-lines, sliding, RV) plus a focused history resolves most dyspnea faster than any single lab.
  • Normal SpO₂ excludes neither PE nor early CO — use the pathway and co-oximetry.
  • A fatiguing asthmatic with a “normal” CO₂ is deteriorating, not improving.
  • GINA 2026: no SABA-only discharge — every asthmatic leaves with ICS-containing therapy.

Pitfalls

  • Normal SpO₂ excludes neither PE nor early CO poisoning (cherry-red skin is uncommon and unreliable).
  • Wheeze in the elderly is not always asthma — think HF (“cardiac asthma”).
  • A fatiguing asthmatic with a “normal” CO₂ is deteriorating, not improving.
  • Diffuse B-lines are not always edema — integrate context (ARDS, pneumonia, fibrosis).
  • Discharging asthma on albuterol alone is outdated and associated with excess exacerbations and death (GINA 2026).
PRACTICE REFRESHER

Rapid recall

Test your first action and the dangerous diagnoses before revealing the answer.

01 · First move

Before you scroll, what needs to happen first?

02 · Immediate threats

Name at least two diagnoses that cannot wait.

PRIVATE TO THIS DEVICE

Your learning note

Capture a weak point, a teaching pearl, or a question to take to your next shift.

Review schedule starts when marked reviewed
Chest PainShockCyanosisHemoptysisECG Guide

Selected guidance · source check 2026-09-07. These 2 source links support selected teaching points, not a complete review of this topic. Check population, setting and local protocol before applying a recommendation.

  • Rosen’s Emergency Medicine, 10th ed. (2023) — dyspnea & respiratory distress
  • GINA 2026 (ICS-formoterol Track 1; no SABA-only therapy)
  • GOLD 2026
  • 2019 ESC/ERS PE Guidelines; 2026 AHA/ACC Acute PE Guideline
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