Reference — Gastrointestinal
Hepatic Encephalopathy
Quick reference for hepatic encephalopathy — causes, ammonia metabolism, asterixis, West Haven grading system, lactulose therapy, and nursing management priorities.
Educational use only. This content is intended for nursing students and exam preparation. Clinical decisions require licensed professional judgment and institutional protocols. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Definition & Pathophysiology
Hepatic encephalopathy (HE) is a neuropsychiatric syndrome resulting from the accumulation of toxins — primarily ammonia (NH₃) — that the failing liver cannot metabolize through the urea cycle.
| Step | Normal Process | In Liver Failure |
|---|---|---|
| Ammonia production | Gut bacteria break down proteins and amino acids → produce NH₃ | Same — continues regardless of liver function |
| Portal absorption | NH₃ absorbed from colon into portal blood → delivered to liver | Same — NH₃ enters portal circulation normally |
| Urea cycle (hepatic) | Liver converts NH₃ → urea → excreted in urine | Urea cycle impaired — NH₃ accumulates in bloodstream |
| Brain effects | Negligible — blood-brain barrier typically prevents NH₃ entry | NH₃ crosses blood-brain barrier → astrocyte swelling, glutamine accumulation → cerebral edema and neurological dysfunction |
Precipitating Causes
Any condition that increases the protein/ammonia load or impairs hepatic function can precipitate HE. Identifying and treating the precipitant is the first treatment priority.
| Precipitant | Mechanism |
|---|---|
| GI bleed | Blood in GI tract is digested as protein → massive ammonia production |
| Infection (SBP, UTI, pneumonia) | Systemic inflammation impairs hepatic function; cytokines directly affect blood-brain barrier |
| Constipation | Prolonged colonic transit increases ammonia absorption from stool |
| Diuretic-induced electrolyte imbalance | Hypokalemia and alkalosis promote NH₃ conversion from NH₄⁺ (ionized, non-crossing form) |
| Sedatives/benzodiazepines/opioids | CNS depressants act synergistically with ammonia toxicity |
| Dehydration | Reduced renal clearance of ammonia; concentrated portal blood |
| High-protein intake | Substrate for ammonia production increases |
| Portosystemic shunts (TIPS) | Blood bypasses liver → ammonia not cleared → HE risk increases post-TIPS |
| Azotemia/renal failure | Impaired renal ammonia excretion → elevated serum ammonia |
Asterixis
Asterixis (flapping tremor or “liver flap”) is the hallmark neurological sign of hepatic encephalopathy and is caused by brief lapses in postural muscle tone.
How to Test
- ✦Ask patient to extend arms out in front with wrists dorsiflexed (hands up like stopping traffic)
- ✦Hold position for 15–30 seconds
- ✦Positive: sudden brief flapping or flapping tremor of the hands (like a bird flapping wings)
- ✦Can also test with eyes closed and tongue protruded
Clinical Significance
- ✦Indicates metabolic encephalopathy (ammonia, CO2 retention, uremia)
- ✦Present in Grade 1–2 HE; may be absent in Grade 3–4 (too obtunded to cooperate)
- ✦Also seen in CO2 retention, uremia, drug toxicity — not specific to liver disease alone
- ✦Document as present/absent with description
West Haven Grading System
| Grade | Consciousness | Cognition & Behavior | Neurological Signs |
|---|---|---|---|
| Grade 0 (Minimal HE) | Normal | Subtle impairment detectable only by psychometric testing (number connection test) | None clinically apparent; may have subtle motor slowing |
| Grade 1 (Mild) | Mild reduction in awareness | Shortened attention span, mild forgetfulness, mild disorientation, sleep-wake inversion | Mild asterixis (flapping tremor); impaired handwriting |
| Grade 2 (Moderate) | Lethargy, moderate reduction in alertness | Obvious disorientation, inappropriate behavior, moderate personality change | Obvious asterixis; dysarthria, ataxia; fetor hepaticus (musty sweet breath) |
| Grade 3 (Severe) | Somnolent but arousable; confused when awake | Profound disorientation, bizarre behavior, difficulty following commands | Asterixis may be absent (too obtunded to cooperate); clonus, rigidity, hyperreflexia |
| Grade 4 (Coma) | Unresponsive — no purposeful response to stimuli | Cannot be assessed | Decerebrate or decorticate posturing; pupillary changes in severe cases; cerebral edema risk |
Lactulose Therapy
Lactulose (Enulose, Generlac) is the first-line pharmacologic treatment for hepatic encephalopathy.
| Mechanism | Lactulose is metabolized by colonic bacteria to lactic acid and acetic acid → acidifies the colon → converts NH₃ (non-ionized, absorbable) to NH₄⁺ (ionized, non-absorbable, trapped in stool) → eliminated in feces. Also acts as osmotic laxative to speed transit and ammonia excretion. |
| Typical dose | PO/NG: 20–30 g (30–45 mL) q1–4h initially; titrate to 2–4 soft bowel movements per day. Rectal enema: 300 mL lactulose + 700 mL water — for patients unable to take orally. |
| Therapeutic goal | 2–4 soft bowel movements per day. Not diarrhea (excessive diarrhea causes dehydration and electrolyte imbalance, worsening HE). |
| Monitoring | Stool frequency and consistency. Electrolytes — hyponatremia, hypokalemia risk with excessive use. Signs of dehydration with over-treatment. |
| Side effects | Flatulence, abdominal cramping, diarrhea (dose-dependent). Nausea and bloating on initiation. Aspiration risk in obtunded patients. |
Nursing Considerations
Safety: fall and aspiration precautions
Confused patients are at high fall risk. Side rails up, bed in lowest position, call bell in reach. Assess gag reflex before any oral intake. Head-of-bed elevation ≥30° for Grade 3–4 HE.
Neurological assessments every 4 hours
Document orientation (person, place, time, situation), behavioral changes, asterixis, speech quality. Use consistent scale (West Haven Criteria). Report worsening of any grade to provider.
Lactulose administration and monitoring
Administer as ordered. Target 2–4 soft stools per day. Document stool frequency, consistency, and color. Excessive diarrhea causes dehydration and electrolyte loss — contact provider.
Identify and treat precipitating cause
Search for GI bleed (melena, hematemesis), infection (CBC, UA, blood cultures per order), constipation, medication culprits. Treating the precipitant often improves HE without additional interventions.
Medication review — avoid CNS depressants
Avoid benzodiazepines, opioids, and other CNS depressants in HE — synergistic toxicity. Flumazenil may reverse benzodiazepine-induced HE. For agitation: low-dose haloperidol is sometimes used with caution.
Nutrition — moderate protein, not zero protein
Protein restriction <0.5 g/kg/day is harmful and no longer recommended. Branched-chain amino acids (BCAAs) are preferred protein source. Small frequent meals. Nocturnal snack reduces catabolism. Zinc supplementation often prescribed.
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with American College of Gastroenterology (ACG) / AGA · ASPEN (nutrition support). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →