In ventricular fibrillation the ventricles quiver in a chaotic way and pump no blood, so the patient is in cardiac arrest. Survival depends on immediate high-quality CPR and defibrillation within minutes.
Key symptoms
- Sudden collapse
- Unresponsive with no normal breathing or only gasping
- Sometimes chest pain or palpitations just before
What you find on exam
- No response to voice or touch
- No pulse on a check of no more than 10 seconds
- After return of pulse: vital signs, oxygen saturation and neurologic status
Tests
- Monitor or AED: chaotic waveform with no clear QRS complexes
- Waveform capnography during CPR; a sudden rise suggests return of pulse
- After return of pulse: 12-lead ECG, troponin, potassium, magnesium and blood gas
Treatment basics
- Start high-quality CPR right away: hard, fast, full recoil, few pauses
- Defibrillate as soon as possible, then 2 minutes of CPR between shocks
- Epinephrine 1 mg IV or IO every 3 to 5 minutes after the second shock
- Amiodarone 300 mg, then 150 mg, or lidocaine for shock-resistant VF
- After return of pulse: treat the cause, control temperature, coronary angiography if STEMI
Red flags
- Unresponsive with no normal breathing: start CPR and get an AED
- VF that keeps returning after shocks
- Low blood pressure or ST elevation after the pulse returns
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Related guides
Sources: AHA Guidelines for CPR and ECC; NASEMSO National Model EMS Clinical Guidelines; NREMT psychomotor skill sheets (EMT and Paramedic). Written by Making Synapses. Making Synapses is not affiliated with these organizations.