Can an unconscious person with fixed and dilated pupils have pulseless electrical activity (PEA)?

Can an Unconscious Person with Fixed and Dilated Pupils Have Pulseless Electrical Activity?

Yes, an unconscious person with fixed and dilated pupils can absolutely have pulseless electrical activity (PEA), and this finding should not be considered an absolute contraindication to resuscitation or a definitive sign of irreversible brain injury.

Critical Context: Fixed Pupils During Resuscitation

The presence of fixed and dilated pupils during cardiac arrest has historically been misinterpreted as indicating irreversible neurological injury. However, current evidence demonstrates that fixed, dilated pupils are frequently seen during cardiopulmonary resuscitation (CPR), particularly after epinephrine administration, and patients have achieved favorable neurological outcomes despite these findings 1.

Key Points About Pupillary Findings in PEA:

• Epinephrine causes pupillary dilation: During active resuscitation with epinephrine (the primary vasopressor for PEA), fixed and dilated pupils are an expected pharmacologic effect, not necessarily a sign of brain death 1

• Pupillary reactivity may predict outcomes but doesn't preclude survival: While the presence of pupillary reactivity at the scene correlates with higher rates of return of spontaneous circulation (48% vs. 16% in those without reactivity), patients without reactive pupils can still survive 2

• Historical contraindications have been revised: The absence of brainstem reflexes with fixed, dilated pupils before cannulation was previously considered a contraindication to advanced support like ECMO, but this has been reconsidered given documented favorable outcomes 1

Understanding PEA as a Clinical Entity

PEA is defined as organized cardiac electrical activity on the monitor without a detectable pulse or blood pressure 3. This represents a critical cardiac arrest state that is distinct from ventricular fibrillation, ventricular tachycardia, and asystole 3.

Diagnostic Confirmation:

• Pulse assessment is unreliable: The ability to diagnose PEA by palpation of the carotid artery has been disputed, with physical examination findings often interpreted incorrectly during emergent evaluation 1

• Bedside cardiac ultrasound is recommended: Ultrasound enables accurate diagnosis of true PEA arrest, evaluation for reversible causes (hypovolemia, tamponade, pulmonary embolism, tension pneumothorax), and differentiation of pseudo-PEA states with actual wall motion 1

Management Approach for PEA with Fixed Pupils

The presence of fixed and dilated pupils should NOT alter the standard PEA resuscitation algorithm:

Immediate Actions:

1. Begin high-quality CPR immediately with minimal interruptions in chest compressions 3

2. Establish vascular access and administer epinephrine 0.01 mg/kg (or 1 mg in adults) IV/IO every 3-5 minutes while CPR continues 3

3. Aggressively search for and treat reversible causes (the "6 H's and 5 T's"):

   • Hypovolemia, Hypoxia, Hydrogen ion (acidosis), Hypo/hyperkalemia, Hypothermia
   • Toxins, Tamponade, Tension pneumothorax, Thrombosis (coronary/pulmonary), Trauma 1

Advanced Considerations:

• Use bedside cardiac ultrasound during rhythm checks (≤10 seconds) to identify reversible causes and confirm true PEA versus pseudo-PEA with cardiac motion 1

• For suspected pulmonary embolism: Consider thrombolysis, surgical embolectomy, or mechanical embolectomy as reasonable emergency treatment options, with early systemic thrombolysis associated with improved outcomes 3

• Higher epinephrine doses may be indicated for specific toxicologic causes like β-blocker or calcium channel blocker overdose 3

Prognostic Considerations

While PEA generally carries a poor prognosis, survival is possible and depends heavily on the underlying cause and initial electrical frequency:

• Higher initial electrical frequencies (>60/min) in PEA are associated with 22% 30-day survival and 15% good neurological outcome—comparable to shockable rhythms 4

• Lower frequencies (10-24/min) carry significantly worse prognosis 4

• PEA represents a late phase in the dying process with tissue hypoxia and metabolic substrate depletion, but is not immediately terminal 5

Case Examples Supporting Survival Despite Fixed Pupils

Documented cases demonstrate recovery despite fixed, dilated pupils:

• A 41-year-old woman with massive carbamazepine overdose presented unconscious with fixed dilated pupils, experienced cardiac arrest, prolonged coma, and seizures, yet eventually recovered and was discharged from hospital 6

• A 19-month-old with methamphetamine toxicity presented with dilated pupils and PEA, received 12 doses of epinephrine, achieved return of spontaneous circulation, and survived 7

Critical Pitfalls to Avoid

Do not prematurely terminate resuscitation based solely on fixed, dilated pupils 1. This finding during active resuscitation:

• May be pharmacologically induced by epinephrine 1
• Does not definitively indicate irreversible brain injury 1, 6
• Should not preclude aggressive treatment of reversible causes 3

Prolonged resuscitation efforts are encouraged in PEA, particularly when the patient is young with a healthy cardiovascular system, as PEA resuscitation is more likely to be successful than asystole 3.