Rapid alveolar fluid accumulation causing severe respiratory distress. Most often cardiogenic from left ventricular failure, hypertensive crisis, ACS, or arrhythmia.
⚠ Red flags
- SBP <90 — cardiogenic shock; avoid GTN
- SpO₂ <85% despite O₂ — escalate to NIV/intubation
- New LBBB — rule out STEMI equivalent
- Acute mitral regurgitation murmur post-MI
Diagnostic criteria
Clinical
- Sudden breathlessness, orthopnoea, pink frothy sputum
- Bilateral fine crackles, raised JVP, S3 gallop
- Diaphoresis, tachycardia, often hypertension
Investigations
- CXR: bilateral infiltrates, cardiomegaly, Kerley B lines, upper lobe diversion
- BNP / NT-proBNP elevated
- Echo: reduced EF or valvular dysfunction
Scoring tools
- Killip class (post-MI)
- Forrester classification
Investigations
Essential
- ECG — look for ACS, arrhythmia, LVH
- CXR (PA)
- ABG, U&E, troponin, BNP/NT-proBNP
- FBC, CRP
Optional
- Echo within 24–48h to characterise LV function and valvulopathy
- Coronary angiography if ACS
- TFTs (precipitant — thyrotoxicosis)
Management
Acute
- Sit upright, legs dependent
- O₂ to maintain SpO₂ ≥94%; CPAP/NIV if respiratory failure
- GTN 0.4–0.8 mg SL then IV infusion if SBP >100
- Furosemide 40–80 mg IV (higher if on chronic loop)
- Treat precipitant: ACS (aspirin + anticoagulation), arrhythmia, hypertensive crisis, sepsis
- Intubation if NIV failure or altered consciousness
Long-term
- Optimise heart failure therapy: ACEi/ARB/ARNI, beta-blocker, MRA, SGLT2i
- Daily weight, fluid and salt restriction
- Cardiac rehab and outpatient follow-up within 2 weeks
Non-pharmacological
- Salt and fluid restriction (1.5–2 L/day)
- Smoking cessation, weight management
- Vaccinations (flu, pneumococcal, COVID-19)
Pharmacological
| Drug | Dose | Notes |
|---|---|---|
| Furosemide | 40–80 mg IV bolus, then infusion 5–20 mg/h | Higher dose if on chronic loop diuretic. Watch K⁺ and Mg²⁺. |
| GTN | 0.4–0.8 mg SL then 10–200 µg/min IV | Avoid if SBP <100 or severe AS. |
| Morphine | 2–4 mg IV slow | Use sparingly — may worsen outcomes; reserve for distress. |
| Noradrenaline | 0.05–1 µg/kg/min IV | Cardiogenic shock with hypotension. |
| Dobutamine | 2.5–10 µg/kg/min IV | Low-output state with adequate pressure. |
Monitoring
- Continuous SpO₂, ECG, BP
- Hourly urine output during acute phase
- Daily weight and fluid balance
- U&E and troponin trends
Referral criteria
- Cardiogenic shock — coronary care/ICU and cardiology
- ACS-related pulmonary oedema — urgent angiography
- Suspected mechanical complication (papillary muscle rupture, VSD)
Complications
- Cardiogenic shock
- Respiratory failure requiring intubation
- Acute kidney injury (cardiorenal syndrome)
- Recurrent decompensation
Special populations
- Pregnancy
- Peripartum cardiomyopathy and pre-eclampsia consideration; multidisciplinary obstetric team.
- Renal impairment
- Diuretic resistance common — combine loop with thiazide; ultrafiltration if refractory.
- Hepatic impairment
- Beware of right-heart failure overlap and ascites; cautious diuresis.
- Elderly
- HFpEF more common; tighter BP control; falls risk on diuretics and vasodilators.
- Paediatric
- Usually congenital cardiac disease — paediatric cardiology lead.