264 Emergency Medicine
benign, with about 33% of patients remaining asymptomatic. This is partially
explained by the fact that β-adrenergic antagonism is often well tolerated in
healthy persons who do not rely on sympathetic stimulation to maintain car-
diac output. Conversely, those with cardiac abnormalities may rely on sym-
pathetic stimulation to maintain HR or cardiac output. The hallmark of
β-adrenergic receptor blocker toxicityisbradycardia with hypotension.
Patients may also exhibit conduction and rhythm abnormalities.Onset of
toxicity usually occurs within 4 hours of ingestion. If a patient remains
asymptomatic after 4 hours there is a low risk for subsequent morbidity
unless a delayed-release preparation is involved.
Management begins with addressing the ABCs. Airway and ventilation
should be maintained with endotracheal intubation if necessary. The initial
treatment of hypotension and bradycardia consists of fluid resuscitation
andatropine.Patients should receive GI decontamination with activated
charcoaland whole-bowel irrigation should be considered in patients who
have ingested sustained-release preparations. Patients with significant tox-
icity (HR < 40, BP < 80, congestive heart failure [CHF], altered mental sta-
tus) should also receive glucagon,which does not rely on β-receptors for
its actions and has both inotropic and chronotropic effects. It also helps
counteract the hypoglycemia induced by β-blocker overdose.
(a)Syrup of ipecac is contraindicated in any patient with depressed or
potentially depressed consciousness. (b and c)Cardioversion is contraindi-
cated in sinus rhythm. It is reserved for “shockable” rhythms such as ven-
tricular fibrillation and pulseless ventricular tachycardia. Epinephrine may
be used if administration of fluids, atropine, and glucagon fails to treat the
patient.(d)This selection may be attempted if the glucagons are ineffective
and the patient continues to decompensate.
243.The answer is c.(Goldfrank et al, pp 1020-1028.)MDMAis cur-
rently one of the most widely abused amphetaminesby college students
and teenagers. It is commonly known as “ecstasy,” “E,” “XTC,” and “M&M.”
MDMA is an entactogen, a substance capable of producing euphoria, inner
peace, and a desire to socialize. Negative effects include ataxia, restlessness,
confusion, poor concentration, and memory problems. MDMA, although
classified as an amphetamine, is also a potent stimulus for the release of
serotonin. MDMA can also cause significant hyponatremia.The increase
in serotonin results in the excessive release of vasopressin (antidiuretic hor-
mone [ADH]). Moreover, large free-water intake (increased thirst) combined
with sodium loss from physical exertion (dancing) certainly contributes to
the development of hyponatremia.