0071643192.pdf

TOXICOLOGY

■ Acute ingestion of organic mercury: Characterized by delayed (and perma-

nent) neurotoxicity—ataxia, dysarthria, constricted visual fields

■ GI symptoms and dermatitis may occur acutely.

DIAGNOSIS

■ Based on presenting symptoms and history of exposure

■ Mercury can be measured in whole blood or urine.

■ Ingested mercury-containing material is usually visible on X-ray.

TREATMENT

■ Whole-bowel irrigation: If radiopaque objects visible on X-ray

■ Antidote = BAL (British anti-lewisite, dimercaprol)or DMSA (2,3-dimer-

captosuccinic acid for symptomatic patients

INHALED TOXINS

Simple Asphyxiants

Simple asphyxiants include carbon dioxide, nitrogen dioxide (silo filler’s dis-

ease), nitrous oxide, methane gas, and helium. Methane gas is present in high

concentrations in bogs of decaying organic matter and in natural gas.

MECHANISM/TOXICITY

■ Produce toxicity by displacing O 2 →hypoxia

SYMPTOMS/EXAM

■ Rapid onset

■ Tachycardia, tachypnea, shortness of breath

■ Dizziness and confusion to coma

■ If untreated may lead to cardiac arrest

DIAGNOSIS

■ Clinical diagnosis is based on history of exposure

TREATMENT

■ Remove patient from source of exposure.

■ Supportive care

■ Administration of O 2

A 40-year-old female presents to the ED with complaints of headache,

nausea, and dizziness. Other family members have recently reported similar

symptoms. She reports recent problems with her water heater at home.

What diagnostic test can most easily aid in the diagnosis?

Carbon monoxide poisoning should always be suspected when several

members of the same household have mild flulike symptoms. A venous or arter-

ial carboxyhemoglobin level greater than 5% (10% in a smoker) confirms the

diagnosis.

Elemental mercury (inhaled)

→respiratory distress.

Inorganic mercury (ingested)

→severe corrosive

gastroenteritis.

Organic mercury (ingested)

→delayed neurotoxicity.