Asterixis

Definition

Asterixis (liver flap) is a non-rhythmic, brief lapse of wrist extensor tone that produces a characteristic flapping motion when the arms are outstretched and the wrists are dorsiflexed. It is a sign of metabolic encephalopathy.

Common Causes

• Hepatic encephalopathy (elevated ammonia)
• Uremia (renal failure)
• Hypercapnia (CO2 narcosis in COPD)
• Severe electrolyte disturbances
• Certain medications (gabapentin, phenytoin)

Assessment Technique

Ask the patient to extend arms forward with wrists dorsiflexed and fingers spread. Observe for 15 to 30 seconds for sudden brief 'flapping' movements.

Nursing Interventions

For hepatic encephalopathy: administer lactulose (goal 2 to 3 soft stools/day), restrict protein only if severe, avoid sedatives, and monitor mental status and serum ammonia. Assess for GI bleeding, a common precipitant. Correct electrolytes and provide seizure precautions.

NCLEX Relevance

Asterixis is a classic cue for hepatic encephalopathy. Lactulose therapy is high-yield (goal: frequent soft stools to trap ammonia).