Pediatric emergency medicine trisk 3098 3098
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (70.93 KB, 1 trang )
levels exceed 400 to 500 mg/dL. Therefore, the sole indication for hemodialysis
is hemodynamic instability. Treatment is otherwise supportive.
Methanol
Although methanol is used primarily as a solvent for industrial purposes, it is
found in other household products, including fuels for stoves, paint removers, and
antifreezes.
Methanol is a model for the few drugs that become more toxic as they are
metabolized. Although methanol has little or no inherent toxicity, its metabolism
by alcohol and aldehyde dehydrogenase to formaldehyde and formic acid creates
highly toxic compounds. Formic acid is a potent organic acid that results in
severe metabolic acidosis and ocular toxicity. Ingestions approaching 0.5 to 1
mL/kg of a 100% solution should be considered dangerous.
The clinical effects of methanol ingestion usually occur after a latent period of
8 to 24 hours. This delay occurs as the result of the metabolic conversion of
methanol to its toxic by-products. In large ingestions, acute methanol poisoning
may cause severe CNS depression, metabolic acidosis, and a number of optic
changes. In the early stages of intoxication, funduscopic examination may be
remarkable for hyperemia. If left untreated, methanol intoxication results in
blindness, with the appearance of a pale, avascular retina. In subacute ingestions,
the nonspecific neurologic symptoms of methanol intoxication resemble those of
ethanol, with a “hangover,” malaise, headache, and dizziness.
The most immediately significant clinical concern from methanol ingestion is
severe metabolic acidosis. This acidosis is primarily the result of formic acid
production. The metabolic acidosis may be intractable and results in multiorgan
dysfunction, which includes cardiac arrhythmias, seizures, and pancreatitis. The
ophthalmologic abnormalities may be temporary or permanent. These include
blurred or double vision, changes in color perception, and sharply reduced visual
acuity. Permanent abnormalities may include diminished pupillary light reaction
or frank blindness. The occurrence of permanent visual defects correlates directly
with the degree of metabolic acidosis, the duration of the acidosis, and the
quantity of methanol ingested.
The treatment of methanol ingestion consists of supportive care, administration
of specific therapies, and enhancement of elimination. Activated charcoal does
not adsorb methanol effectively and is unnecessary.
Laboratory assessment includes serial blood gases, electrolytes, BUN,
creatinine, glucose, serum osmolality, and methanol levels. Because serum
methanol concentrations are only available as “send out” tests at many hospitals,
