What is the most common cause of pulseless electrical activity (PEA) arrest?

Most Common Causes of PEA Arrest

The most common causes of PEA arrest are hypoxia (23.6%), acute coronary syndrome (12.5%), and trauma (12.5%), with hypoxia being the single most frequent etiology. 1

Primary Etiologies Based on Clinical Evidence

The traditional "H's and T's" mnemonic provides a framework, but real-world data reveals a different frequency distribution than commonly taught:

Most Frequent Causes (in order of prevalence):

• Hypoxia accounts for nearly one-quarter of all PEA arrests (23.6%) and represents the most common reversible cause 1
• Acute coronary syndrome occurs in 12.5% of cases, particularly in patients with preexisting severe left ventricular dysfunction where acute coronary occlusion produces immediate pump failure 1, 2
• Trauma represents 12.5% of PEA arrests 1
• Nonischemic cardiac disorders (8.3%) and intracranial hemorrhage (6.9%) are significant causes that equal or exceed the frequency of several traditional "H's and T's" etiologies 1

Less Common Traditional Causes:

• Pulmonary embolism, hypovolemia, intoxication, and electrolyte abnormalities each occur in fewer than 10% of cases, despite being prominently featured in teaching mnemonics 1
• Unidentified causes account for 17.4% of cases, highlighting the importance of systematic evaluation 1

Clinical Approach to Diagnosis

The American Heart Association emphasizes that PEA is often caused by reversible conditions that can be successfully treated if identified and corrected promptly 3, 4. During each 2-minute CPR cycle, providers should systematically recall the "H's and T's": hypovolemia, hypoxia, hydrogen ion (acidosis), hypo/hyperkalemia, hypothermia, toxins, tamponade, tension pneumothorax, thrombosis (coronary or pulmonary), and trauma 3.

Bedside Ultrasound as Diagnostic Tool:

Bedside cardiac ultrasound should be performed immediately in PEA to accurately diagnose true PEA arrest, evaluate for reversible causes (hypovolemia, pericardial effusion/tamponade, pulmonary embolism, tension pneumothorax), and differentiate pseudo-PEA states with wall motion. 3, 5

• Echocardiography can identify several causes not detectable by other bedside methods, including pulmonary embolism, severe ventricular dysfunction, hypovolemia, and mass lesions 5
• The examination should not interrupt chest compressions for more than 10 seconds 3, 5
• Physical examination findings, including pulse assessment, are frequently interpreted incorrectly during cardiac arrest 3, 5

Critical Management Implications

Immediate Resuscitation:

• High-quality CPR with minimal interruptions should be initiated immediately, with epinephrine 1 mg IV/IO administered as soon as feasible and repeated every 3-5 minutes 4
• Given the high frequency of hypoxia as a cause, placement of an advanced airway is theoretically more important in PEA than in VF/pulseless VT arrests 3

Cause-Specific Interventions:

• For suspected pulmonary embolism: Thrombolysis is reasonable as emergency treatment, with early administration associated with improved outcomes compared to use after conventional ACLS failure 4, 6
• For tension pneumothorax: Immediate needle decompression should be performed if clinically suspected 3
• For hypovolemia/sepsis: Empirical IV/IO crystalloid administration is potentially beneficial 3
• For acute coronary syndrome: Patients with baseline left ventricular dysfunction who develop PEA should be evaluated for acute coronary occlusion, as this produces PEA through acute pump failure occurring within 2 minutes of occlusion 2

Common Pitfalls to Avoid

• Do not rely solely on the traditional "H's and T's" frequency assumptions - hypoxia is far more common than many of the memorized causes 1
• Do not overlook intracranial hemorrhage and nonischemic cardiac disorders as these represent significant causes with prevalence equaling or exceeding classical etiologies 1
• Do not delay bedside ultrasound - it provides critical diagnostic information not available through other point-of-care techniques 5
• Do not assume pulse assessment is reliable - physical examination findings are often misinterpreted during emergent evaluation 3, 5