GRAND ROUNDS 03 · DISEASE EDUCATION

CHF · Pulmonary Edema

Acute cardiogenic pulmonary edema — the failing pump floods the lungs
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Acute cardiogenic pulmonary edema = left-ventricular failure → back-pressure floods the alveoli. ↓LV output raises filling pressure; it backs up the pulmonary circuit until hydrostatic pressure > oncotic and fluid pours into the air sacs. SCAPE = Sympathetic Crashing Acute Pulmonary Edema — the hypertensive flash: minutes, not days. Usually fluid MALDISTRIBUTION, not overload.
1Pathophysiologythe vicious cycle
1↓ LV function — ischemia, HTN crisis, arrhythmia or valve → the ventricle can't eject → forward output falls.
2↑ LVEDP — blood dams behind the LV → left-atrial & pulmonary-venous pressure climb.
3Pulmonary congestion — pressure transmits to the pulmonary capillaries (hydrostatic ↑).
4Alveolar flooding — hydrostatic > oncotic → transudate crosses into interstitium, then into the alveoli.
5V/Q mismatch → hypoxia — fluid widens the diffusion distance; shunt → hypoxemia, air hunger.
6Sympathetic surge — distress → catecholamines → ↑ afterload + ↑ HR → the LV works harder → worse.
↻ SCAPE spiral: afterload ↑ → output ↓ → congestion ↑ → sympathetic surge ↑ → afterload ↑
2Presentation

Classic: abrupt severe dyspnea, orthopnea, PND, air hunger, anxiety, diaphoresis; often hypertensive (SCAPE, SBP frequently >180).

Exam: bibasilar → diffuse crackles, frothy ± pink-tinged sputum, S3 gallop, tachypnea, accessory-muscle use, cool clammy skin; may wheeze ("cardiac asthma").

Distinct from "dry" dyspnea: wet lungs, sudden onset, hypertensive, sits bolt upright — responds to nitrates + NIV, not bronchodilators.

SSeverityread the BP · pick the pathway
PATTERNBPONSETTHE FIX
SCAPESBP>180minutesNIV + high-dose nitro
Decomp. HFnormal/↑daysnitro + diurese (real overload)
Cardiogenic shockSBP lowhourspressor/inotrope — NOT nitrates

SCAPE is the hypertensive crash — hypoxic, panicked, flooding fast. Treat the blood pressure; it is usually maldistribution, not litres of extra fluid.

PPrecipitantsfind & fix the trigger
Ischemia / ACSHypertensive crisisArrhythmia (AF-RVR) Valve failure (MR/AS)Med / diet nonadherenceRenal failure Infection / sepsisAnemia · thyroid
DDifferentialnot all that's wet or wheezes
  • Cardiac "asthma" (this)
  • True asthma
  • COPD exacerbation
  • Pulmonary embolism
  • Pneumonia / sepsis
  • ARDS (non-cardiogenic)
  • Flash from renal / valve
  • Anaphylaxis

The trap: mistaking cardiac asthma for COPD/asthma and reaching for bronchodilators + steroids while the pump keeps flooding.

▲Failing Pump → Wet Lungsback-pressure floods the alveoli
the central lesion
↓ LV OUTPUT · ↑ FILLING PRESSURE · ALVEOLAR FLOODING rust = back-pressure · gold = O₂
RA RV LA LV dilated · weak ↓ ejection fraction AIR thin interface NORMAL ALVEOLUS dry · O₂ crosses freely ✕ O₂ blocked EDEMATOUS ALVEOLUS flooded · thick interface · hypoxemic pressure backs up the pulmonary circuit → hydrostatic > oncotic → fluid floods the sac ↑ diffusion distance → hypoxemia
Back-pressure
↓LV output → ↑LVEDP transmits to pulmonary veins.
Flooding
Hydrostatic beats oncotic → transudate fills the sac.
Hypoxia
Fluid widens the diffusion path → V/Q shunt.
4Diagnosticsit's clinical — confirm the pattern

Bedside: clinical dx first — monitor, IV, SpO₂. Lung ultrasound: diffuse bilateral B-lines (>3/field) — fast, sensitive for interstitial edema.

ECG: hunt the trigger — STEMI / ischemia, AF with RVR, arrhythmia. Troponin for ACS.

CXR: cephalization, Kerley-B lines, perihilar "bat-wing", effusions — don't wait for it. BNP supports HF when the diagnosis is unclear (context, not the acute driver); echo for EF, valve, wall motion.

LUNG ULTRASOUND — B-LINES "wet" lung · comet tails
pleural line A-lines (dry) B-lines (wet — pulmonary edema)
FFrank–Starlingwhy more filling stops helping
THE FAILING CURVE stroke volume vs LV filling pressure
CONGESTION pulmonary edema LV filling pressure (LVEDP / preload) → stroke volume → NORMAL FAILING normal op. CHF op. — high pressure, low output, floods lungs nitro + NIV shift left → ↓congestion
5Treatmentthe SCAPE sequence · per protocol
Sit up, legs down + high-flow O₂ to SpO₂ ≥94%. Calm, coach, monitor.
CPAP / NIV — EARLY CPAP 5–10 cmH₂O. ↓ preload & afterload, recruits alveoli, cuts intubation (3CPO / meta-analyses).
Nitroglycerin — the workhorse. SL 0.4 mg q3–5 min → IV infusion, high-dose in the hypertensive crash. Venodilation → preload↓; higher doses → afterload↓.
Treat the trigger — ischemia (ASA / cath), arrhythmia (rate/rhythm, cardiovert AF-RVR), valve, HTN crisis.
Diuretics furosemide IV — adjunct acutely; for true volume overload. Not the fix for SCAPE maldistribution.
Refractory: inotrope/pressor only if hypoperfused; intubate if NIV fails. Morphine — avoid.
7Critical ProceduresNIV first — earn the tube
⚠ CPAP / BiPAP — and when to intubate
  • CPAP first: tight mask seal, start 5 → titrate to 10 cmH₂O. Recruits flooded alveoli, drops preload & afterload, offloads work.
  • BiPAP if tiring / hypercapnic — adds pressure support on top of PEEP.
  • Reassess in minutes — NIV works fast; most improve and avoid the tube.
  • Intubate for: failing NIV, exhaustion, ↓GCS, can't protect airway, persistent hypoxia despite max therapy.
  • Avoid intubation if NIV is working — positive-pressure induction can drop the BP; in SCAPE afterload reduction usually helps.
PPitfalls & Pearls
  • SCAPE is maldistribution, not overload — nitrates + NIV beat aggressive diuresis; many patients are euvolemic.
  • Treat the blood pressure. The hypertensive crash needs afterload reduction, not a fluid bolus.
  • Don't mistake cardiac asthma for COPD/asthma — bronchodilators waste the golden window while the pump floods.
  • NIV early cuts intubation (3CPO: faster physiologic recovery; meta-analyses ↓ intubation & mortality).
  • Nitrates > morphine — morphine is out (↑ mortality, respiratory depression).
  • Cold + wet (hypotensive) = cardiogenic shock → NOT nitrates; needs inotrope/pressor.
REMEMBER — Sit Up · O₂ · CPAP early · high-dose NITRO · fix the trigger. SCAPE = maldistribution — treat the BP; diuretics adjunct. Cold + wet ≠ nitrates.
DDisposition
ADMIT / ICU
  • NIV-dependent / ongoing hypoxia
  • ACS or arrhythmia trigger
  • Cardiogenic shock, pressor need
  • Refractory to nitro + NIV
OBS / FLOOR
  • Rapid response to nitro + NIV
  • Trigger identified & treated
  • Normotensive, self-ventilating
  • Cardiology follow-up arranged
Sheet
CHF / Acute Pulmonary Edema
Series / No.
GRAND ROUNDS 03
Part No.
CC-GR-03
Rev
A
Status
EDUCATION REFERENCE — NOT A PROTOCOL. VERIFY LOCALLY.

SOURCES: 2022 AHA/ACC/HFSA & 2021 ESC Heart Failure Guidelines · Gray et al., 3CPO Trial, NEJM 2008;359:142 (NIV in cardiogenic edema) · SCAPE / high-dose nitroglycerin literature (Wilson & Reardon; HI-DOSE SCAPE) · Marino, The ICU Book; Tintinalli, Emergency Medicine. Doses educational — not medical advice & not a protocol; reference for trained clinicians only. Verify all drugs, doses & treatments against local protocol & current guidelines. Full disclaimer: crashcard.co/legal. © 2026 Claustrum LLC d/b/a Crash Card · crashcard.co · Printed in Minnesota.