Approach Considerations
Treatment of acute inorganic arsenic toxicity is supportive. Chelation therapy should be considered in symptomatic patients. The efficacy of chelation therapy in providing either laboratory or clinical improvement in intoxicated patients is lacking. Chelation is not indicated for arsine gas exposure.
Generally, organic arsenical compounds found in the urine are not an indication of arsenic toxicity and do not warrant therapeutical intervention.
Arsenic clearance by dialysis is substantial, and hemodialysis may be indicated if available within a short time after exposure. However, hemodialysis, in the absence of renal failure, has not been shown to alter medical outcome.
Once arsenic distributes into the tissues, treatment may be unsuccessful. Clinical trials are not available, but attempting to remove arsenic from the plasma before it reaches the tissues makes sense.
In arsine exposure, hemolysis may be severe and life threatening, and no data suggest that chelation therapy can alter this. Arsine appears to rapidly bind to the erythrocytes, making them likely to lyse and release more toxin to contaminate other cells. The use of multiple transfusions and perhaps exchange transfusion may be necessary.
Many patients will develop profound peripheral neuropathy requiring extensive rehabilitation. Rehabilitation should be started as promptly as the clinical picture allows.
Emergency Department Care
Hemodynamic stabilization is of primary importance, and large amounts of crystalloid solutions may be required because of significant gastrointestinal (GI) losses (ie, vomiting, diarrhea). In the face of acute blood loss, the use of blood products may be critical in sustaining the life of the victim.
The use of GI decontamination is controversial and may confuse the clinical picture. For acute arsenic ingestions, orogastric lavage is recommended if the patient presents rapidly or plain radiography indicates that arsenic is present in the stomach. Activated charcoal does not adsorb arsenic appreciably and is not recommended for patients in whom co-ingestants are not suspected. Whole bowel irrigation with polyethylene glycol may be effective to prevent GI tract absorption of arsenic. The use of invasive gastric-emptying procedures has been reported in dire cases, but these attempts do not seem to be fruitful.
Do not delay provision of definitive chelation therapy and hemodialysis.
Chelation
Chelation should be performed in patients with symptomatic arsenic toxicity, although the evidence of therapeutic benefit from chelation derives largely from animal studies. Chelation is principally useful for acute toxicity. In such cases, chelation should be started as soon as possible, because its efficacy declines rapidly with increasing time after exposure. [28] Chelation should be performed in consultation with a medical toxicologist, since it carries risks and not all cases of arsenic toxicity require chelation.
The following agents are used for chelation of arsenic [29] :
-
Dimercaprol (British anti-lewisite [BAL]
-
Succimer (dimercaptosuccinic acid [DMSA])
-
Dimerval (dimercaptopropane sulfonate [DMPS])
In the United States, dimercaprol is the first-line agent for treating arsenic poisoning, but it is often in short supply. In animal experiments, repeated administration of dimercaprol has increased the brain uptake of arsenic. [30] Succimer and dimerval, which are water-soluble analogs of dimercaprol, have a higher therapeutic index than dimercaprol, but succimer is licensed in the United States only for use in childhood lead poisoning, and dimerval is not licensed for use in the US, although it is the international drug of choice for this indication. [29]
Sterile abscesses after the use of dimercaprol (BAL in oil) are not unusual. They initially may appear like erythematous macules, which spread or coalesce, and may continue to drain for some time.
Consultations
Consultations may include the following:
-
Consult a hematologist and nephrologist in cases of arsine exposure.
-
Neurology and physiatry consultations are appropriate in cases of arsenic-induced neuropathy.
-
Consultation with a medical toxicologist conversant with the use of chelation therapy may be very useful.
-
Psychiatric consultation is necessary before discharge if the arsenic ingestion was intentional.
Long-Term Monitoring
Perform a careful neurological evaluation in follow-up of all patients because the peripheral neuropathy, which may develop after an acute exposure, may not appear for 2-3 weeks.
-
"Blackwater" urine due to massive hemolysis, from a patient exposed to arsine at a gas tank cleaning operation.
-
Mees lines, or leukonychia, are transverse white bands with no palpable ridges that appear on the fingernails as a result of arsenic poisoning, certain cancers, and treatment with certain chemotherapy agents. Courtesy of Wikimedia Commons (Author Yannick Trottier) (https://commons.wikimedia.org/wiki/File:Mees%27_lines.jpg).
