PEDBASE.org - The Pediatric Database - Detailed information of ACETAMINOPHEN OVERDOSE

ACETAMINOPHEN OVERDOSE

DEFINITION:

An acute toxic ingestion of acetaminophen.

EPIDEMIOLOGY:

incidence: ?
age of onset:
- any
risk factors:
- suicidal ideation

PATHOGENESIS:

1. Sources of Acetaminophen

Tylenol, Tempra

2. Toxicity

1. >150 mg/kg

is considered toxic and the dosage at which N-acetylcysteine therapy is initiated if the plasma acetaminophen level is unavailable

2. Rumack-Matthew Nomogram

first published in Pediatrics 55:871 (1975)
used to assist in predicting the degree of toxicity after an acute, single ingestion of acetaminophen

3. Pathogenesis

1. Hepatocellular Damage

acetaminophen is metabolized by cytochrome P450 and glutathione in the liver to a mercapturic acid conjugate
with an overdose, the hepatic stores of glutathione are depleted to <70% of normal resulting in toxic damage by a highly reactive intermediate from the acetaminophen metabolic pathway

CLINICAL FEATURES:

1. Stage I (Day 1)

anorexia, diaphoresis, lethargy, malaise, nausea & vomiting, pallor

2. Stage II (Day 2)

Stage I symptoms disappear
hepatic necrosis begins:
- abdominal pain and tenderness, hepatomegaly
- elevated AST, ALT, bilirubin, PT

3. Stage III (Days 3-4)

Stage I symptoms reappear
hepatic necrosis peaks:
- jaundice, encephalopathy, acute renal failure, bleeding, hypoglycemia

4. Stage IV (after Day 4)

resolution of symptoms and hepatic dysfunction

INVESTIGATIONS:

1. Serum

liver function tests (AST, ALT, bilirubin), glucose, BUN, creatinine, PT daily if acetaminophen levels are in the toxic range
drug screen (for other toxins)

2. Urine

drug screen (for other toxins)

MANAGEMENT:

I. INITIAL MANAGEMENT

A. Airway

B. Breathing

C. Circulation

if hemodynamically unstable
Normal Saline or Ringers at 10-20 cc/kg IV over 1 hour

D. Draw Blood

liver function tests, PT, glucose, BUN, creatinine
acetaminophen level (if >4 hours post ingestion)

E. Eliminate

1. Syrup of Ipecac

induces vomiting and therefore must position child on the left side with head down to protect the airway
dose (followed by a clear liquid [water])
- 10 cc in patients .5-1 years of age
- 15 cc in patients 1-2 years of age
- 20 cc in patients 2-12 years of age
- 30 cc in patients over 12 years of age
best given within 1 hour of ingestion
save initial emesis for analysis
contraindications: coma, convulsions, significant risk of aspiration, infants <6 months of age

2. Gastric Lavage

insert a large bore NG tube and check position
suction out stomach contents and save for analysis
place patient on side
inject 15 cc/kg of saline per lavage
contraindications: unprotected airway, coma, convulsions

3. Activated Charcoal

not recommended if using oral N-acetylcysteine

II. MAINTENANCE THERAPY

1. N-Acetylcysteine (Mucomyst)

begin within 10 hours of ingestion if possible but may be used as late as 24 hours post ingestion
indicated if plasma acetaminophen level is in the toxic range or if the level is not available, the ingested dose is >150 mg/kg
administer orally or via NG tube
loading dose:
- 140 mg/kg/dose po diluted in 3 volumes of soft drink
maintenance dose:
- 70 mg/kg/dose po q4h x 17 doses (for 3 days)

2. Hepatic Toxicity

consult Gastroenterologist
decrease protein intake
bowel decontamination with neomycin
antacids to prevent bleeding

3. Prognosis

mortality rate is <0.5%
there is no long term sequelae after acute toxicity

Pediatric Database - ACETAMINOPHEN OVERDOSE

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