15.2 Dysrhythmias
Key Takeaways
- Shock ventricular fibrillation and pulseless ventricular tachycardia immediately; add epinephrine and an antiarrhythmic for shock-refractory arrest.
- Unstable SVT, atrial fibrillation, or ventricular tachycardia with a pulse gets synchronized cardioversion; adenosine is for regular narrow-complex tachycardia.
- Symptomatic bradycardia is atropine, then pacing or a catecholamine infusion; do not watch a dying rate to cruise altitude.
- Wide-and-slow or sine-wave hyperkalemia needs calcium, then shift and remove potassium; TCA wide-complex toxicity needs sodium bicarbonate, not amiodarone.
- Confirm pads and energy, keep oxygen from blowing across the chest, never shock in pooled fuel, and clear the crew in a metal cabin.
A loud cabin will not tell you the patient is unstable—the blood pressure, the mentation, and the chest pain will. Domain 4.B.3 of the August 2026 Board of Certification for Emergency Nursing (BCEN) Certified Flight Registered Nurse (CFRN) outline tests dysrhythmias as an Advanced Cardiovascular Life Support (ACLS)-style stability decision you must make before the next climb. Electricity, a drug, or a magnet is the therapy. Watching a printable strip while the pressure disappears is not.
Unstable versus stable, and who gets shocked
Unstable means the rhythm is causing hypotension, acute heart failure, ischemic pain, or shock. A fast, organized rhythm with a pulse that is killing perfusion gets synchronized cardioversion. A pulseless, chaotic, or disorganized shockable rhythm gets unsynchronized defibrillation. Stable patients get oxygen, an electrocardiogram (ECG), a cause hunt, and a drug or a destination consult—not a casual shock in a metal tube.
Pulseless VF and pVT
Ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT) are defibrillated immediately. Use the defibrillator's labeled biphasic energy; 2025 American Heart Association (AHA) teaching does not pick one universal joule number, and if the device card is unknown many crews use maximal energy. High-quality cardiopulmonary resuscitation (CPR) still matters in a cramped cabin: hard surface, limited interruptions, rotate compressors. Epinephrine 1 mg intravenous (IV) or intraosseous (IO) every 3–5 minutes and amiodarone 300 mg then 150 mg (or lidocaine per protocol) are the shock-refractory drugs—ACLS teaching, not BCEN statutes. Treat reversible causes while you shock.
Synchronized cardioversion, adenosine, and the slow heart
Unstable supraventricular tachycardia (SVT), atrial fibrillation (AF), atrial flutter, or monomorphic ventricular tachycardia (VT) with a pulse is a synchronized shock. Sedate if the patient is conscious and the clock allows. 2025 AHA-style teaching prefers a high first shock for AF and flutter (often at least 200 J biphasic) and tells you to follow the device card for other rhythms; if you do not know the card, maximal energy is acceptable teaching. Do not deliver an unsynchronized shock into a pulse unless the rhythm is polymorphic VT or the defibrillator will not sync.
Adenosine 6 mg rapid IV, then 12 mg if needed, is for regular narrow-complex tachycardia—not irregular wide-complex AF, and not a reason to delay cardioversion in a crashing patient. Atropine 1 mg IV, repeatable to 3 mg, is first-line for symptomatic bradycardia. If the rate and pressure stay dead, start transcutaneous pacing or an epinephrine or dopamine infusion. Capture is electrical and mechanical—feel a pulse that matches the paced rate. Complete heart block after an inferior ST-elevation myocardial infarction (STEMI) is a pacing and destination problem, not a third atropine experiment at 4,000 feet.
| Rhythm / problem | Unstable action | Drug or caveat |
|---|---|---|
| VF / pulseless VT | Unsynchronized defibrillation | Epinephrine; amiodarone or lidocaine if refractory |
| Unstable SVT, AF, or VT with a pulse | Synchronized cardioversion | Sedate if feasible; follow device energy |
| Regular narrow-complex SVT | Vagal maneuvers, then adenosine if still stable enough | Do not use adenosine for irregular wide-complex AF |
| Symptomatic bradycardia | Atropine, then pacing or a catecholamine drip | Confirm mechanical capture |
Hyperkalemia, TCA toxicity, and the magnet
A wide, slow, or sine-wave rhythm in a dialysis, crush, or succinylcholine-risk patient is hyperkalemia until proven otherwise. Stabilize the membrane with calcium (chloride through a working central or large line; gluconate is acceptable if that is what you carry). Then shift potassium with insulin plus glucose, nebulized albuterol, and bicarbonate if the patient is acidotic. Remove what you can: a loop diuretic if the kidneys still work, and a dialysis destination. Amiodarone and a hopeful shock do not fix a potassium channel crisis.
Tricyclic antidepressant (TCA) overdose is a different wide-complex toxin. Sodium bicarbonate boluses, then an infusion, narrow the QRS and treat the hypotension. Hyperventilate a bit after the airway is secure. Do not reach for a class I antiarrhythmic. Physostigmine is not the flight drug for a wide TCA QRS.
A permanent pacemaker or implantable cardioverter-defibrillator (ICD) is a program-protocol device. A magnet over many ICDs suspends tachyarrhythmia therapies (inappropriate shocks) while leaving pacing intact. A magnet over many pacemakers forces asynchronous pacing. Exact behavior is manufacturer- and mode-specific. Use the magnet when the device is shocking a conscious patient for artifact or when asynchronous pacing is the planned bridge, and document it for the receiving team.
Electricity in a metal cabin
Confirm hands-free pads before you need them. Anterior-posterior placement is fine if a dressing owns the usual landmarks. Select the energy on the ground when you can still read the card. Do not defibrillate in pooled fuel, and do not leave oxygen blowing across a wet chest—move the free-flowing source, then clear. A metal airframe is not a reason to withhold a needed shock and not an excuse to skip the clear. Call “all clear,” look at every set of hands, and discharge. After return of circulation, recheck the tube, the pressure, and the destination: a catheterization laboratory or intensive-care unit, not a clinic that cannot pace.
- Shock VF and pulseless VT; synchronize unstable SVT, AF, and VT with a pulse.
- Use adenosine only for regular narrow-complex tachycardia.
- Pace or start a drip if atropine fails a symptomatic bradycardia.
- Calcium, then shift and remove, for hyperkalemia; bicarbonate for a TCA-wide QRS.
- Pads on, energy selected, oxygen off the chest, no shock into fuel, crew clear.
You are about to defibrillate pulseless ventricular fibrillation on a roadside landing zone next to a leaking fuel bladder, with a nonrebreather blowing across a wet chest. What is the correct electricity plan?
An interfacility patient with atrial fibrillation at 180 beats per minute is hypotensive, diaphoretic, and barely answering. What is the indicated electrical therapy?
A dialysis patient develops a sine-wave wide-complex bradycardia and a falling pressure during packaging. What is the first membrane and potassium plan?