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Approach to acute dyspnoea in the emergency department
In acute dyspnoea, first decide whether the patient is about to tire and stop breathing, give oxygen to the right target, and at the same time separate airway, lung, cardiac, embolic and metabolic causes — with examination, blood gases, POCUS and BNP.
Why it matters in the exam
The exam tests the decision on respiratory support: when to use NIV (mainly in COPD with respiratory acidosis and in cardiogenic pulmonary oedema), when to intubate, and what the saturation target is — 94–98% for most patients, 88–92% for those at risk of carbon-dioxide retention. A standard distractor is high-flow oxygen without a target in a COPD patient.
Further questions test differentiation: "wet" lungs with B-lines and a high BNP (heart failure), wheeze (asthma or COPD), absent lung sliding (pneumothorax), clear lungs with tachycardia (embolism) and deep rapid breathing with acidosis (DKA).
Many questions show a breathless patient with a blood-gas result and ask you to read the pH and carbon dioxide to choose the type of support. Acute respiratory acidosis with a low pH means ventilatory failure and needs ventilatory support, not oxygen alone; hypoxaemia with a low PaCO2 means an oxygenation problem. Know when NIV is unsuitable — reduced consciousness, vomiting, copious secretions or haemodynamic instability — because then intubation is the right step.
Key points
- Recognise respiratory fatigue and decide early on intubation.
- Saturation target 94–98%; 88–92% when at risk of CO2 retention.
- NIV for COPD with respiratory acidosis and for cardiogenic pulmonary oedema.
- POCUS and BNP separate heart from lung.
- Also think of embolism, DKA and anaemia.
Summary table
| Group | Examples | Key clue | Helpful test |
|---|---|---|---|
| Upper airway | Foreign body, anaphylaxis, epiglottitis | Stridor, voice change | Direct examination, airway preparation |
| Lung | Asthma, COPD, pneumonia, pneumothorax | Wheeze, fever, absent breath sounds | Chest X-ray, POCUS, blood gas |
| Heart | Pulmonary oedema, ACS, tamponade | Crackles, full neck veins, orthopnoea | BNP or NT-proBNP, POCUS, ECG |
| Pulmonary vessels | Pulmonary embolism | Sudden, clear lungs, risk factors | Wells, D-dimer, CT angiography |
| Metabolic and other | DKA, anaemia, anxiety, neuromuscular weakness | Kussmaul breathing, pallor, low vital capacity | Blood gas, haemoglobin, FVC |
A free exam question
בת 63 , ברקע סרטן שד עם גרורות לכבד ולריאות. לאחר מספר קווי טיפול אשר כשלו, לפני כשבוע הוחלט להפסיק את הטיפול האונקולוגי. כעת ממתינה למקום בהוספיס מוסדי. מהבוקר קוצר נשימה, מתארת תחושה של חנק. מדדים: דופק 120, לחץ דם 135/89, חום 36.5, סטורציה 95% באוויר חדר. לפי המאמר: ONCOLOGIC EMERGENCIES: PALLIATIVE CARE IN THE EMERGENCY DEPARTMENT SETTING מה הטיפול המומלץ? (the question as examined, in Hebrew)
- א. קטמין KETAMINE .( תוך ורידי
- ב. מורפין MORPHINE .( תוך ורידי
- ג. חמצן דרך משקפי חמצן
- ד. חמצן דרך מסיכה ושקית העשרה
In the full version for subscribers
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Sources
- BTS Guideline for oxygen use in healthcare and emergency settings, 2017 — Target saturations
- ERS/ATS Clinical Practice Guidelines: noninvasive ventilation for acute respiratory failure, 2017 — Indications for NIV
- ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure, 2021 (2023 focused update) — Natriuretic peptides in acute dyspnoea
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.