Poisoning and Overdose Answers 259233.The answer is a.(Goldfrank et al, pp 480-496.)NACis the cornerstone
of therapy for the potentially lethal acetaminophen overdose. NAC acts as a
glutathione precursor to reduce NAPQI (N-acetyl-p-benzoquinoneimine), the
toxic metabolite of acetaminophen. It can be administered orally or intra-
venously. NAC is most effective if administered within 8 hours of the inges-
tion; however, it may still be of benefit if given more than 24 hours after an
acute acetaminophen overdose.
(b)Physostigmine is used for an anticholinergic overdose. (c)Flumazenil
is a benzodiazepine antagonist used occasionally in a benzodiazepine overdose.
Its use can precipitate benzodiazepine withdrawal and seizures in chronic ben-
zodiazepine users. (d)Naloxone is a μ-receptor antagonist and is used in opioid
overdoses. (e)Digibind is the antidote for digitalis glycoside poisoning.
234.The answer is b.(Rosen, pp 2129-2133.)Ethylene glycolis a colorless,
odorless, slightly sweet-tasting liquid that is found in antifreeze. Ingestions of
antifreeze are either accidental, suicidal, or in substitute of ethanol. Ethylene
glycol is metabolized to glycolic acid, which results in a profound anion gap
metabolic acidosis(Na)−([Cl] + [HCO 3 ]); (139 −[101 + 14]) = 24. Glycolic
acid is subsequently metabolized to oxalic acid, which combines with calcium
to form calcium oxalate crystals, which then precipitate in renal tubules, brain,
and other tissues. The finding of crystalluriais considered the hallmark of
ethylene glycol ingestion;however, its absence does not rule out the diagno-
sis. Another useful test in the ED involves examining freshly voided urine for
fluorescence with a Wood lamp. Sodium fluorescein is added to antifreeze to
aid in the detection of radiator leaks. Ingestion of ethylene glycol is associated
with neurologic, cardiopulmonary, and renal abnormalities.
(a)CO poisoning can cause a metabolic acidosis. However, this patient’s
CO level is within normal limits. (c)Diabetic ketoacidosis can cause a meta-
bolic acidosis. Patients usually have a history of diabetes, elevated blood
glucose (> 200 mg/dL), and ketones in their urine. (d)Lactic acidosis can cause
a metabolic acidosis. This patient’s lactate is within normal limits. (e)Isopropyl
alcohol (rubbing alcohol) is less toxic than methanol and ethylene glycol, but
more toxic than ethanol. Patients typically present with CNS depression. Iso-
propanol also causes a hemorrhagic gastritis. Unlike the other toxic alcohols,
it is not associated with a high anion gap metabolic acidosis, unless hypoten-
sion is present.
235.The answer is e.(Goldfrank et al, pp 1478-1486.)CO poisoningis
the leading cause of poisoning morbidity and mortality in the United States.