0071643192.pdf

TOXICOLOGY

COMPLICATIONS

■ Delayed or persistent neurocognitive deficits on neuropsychiatric testing.

■ HBO therapy may prevent the development of these effects but studies

are not conclusive.

A 25-year-old male is brought to the ED after being found unresponsive

inside a burning house. He was intubated by EMS en route. On arrival he

is hypotensive, comatose, and markedly tachypnic. There is no evidence of

trauma or skin/airway burns. ABG reveals a severe metabolic acidosis and a nor-

mal measured PaO 2. What is the most appropriate next step?

This patient should be presumed to have a combined CO and cyanide (CN)

poisoning based on his hemodynamic instability and coma. Initial treatment of

CO poisoning consists of O 2 therapy, which has already been initiated. The next

most appropriate step, therefore, is administration of either hydroxycobolamin

or sodium thiosulfate for treatment of CN poisoning. In the smoke inhalation vic-

tim, administration of nitrites is not recommended, as a nitrite-induced methe-

moglobinemia will further decrease tissue O 2 delivery in the CO-poisoned

patient. If the COHb level is low on co-oximetry, nitrites may be initiated.

Cyanide

Cyanide (CN) is a rapid-acting, highly toxic poison found in a wide variety of

chemicals. Poisoning is rare in the United States as few household products

contain CN.

Sources of CN include:

■ Combustion of plastics, synthetic fibers, or wool

■ House fires (smoke inhalation) represent the most likely source of

exposure.

■ Prolonged infusion of nitroprusside

■ Industry, including mining, plastics manufacturing, welding, fumigation,

chemical synthesis, and research

■ The pits and seeds of certain fruits (apricots, bitter almonds) contain a

compound amygdalin, which releases CN in vivo during its metabolism.

TABLE 6.20. Indications for HBO Treatment of CO Poisoning

Any history of syncope

Evidence of major end-organ damage

Persistent neurologic symptoms

Pregnancy

COHb level > 20—25%