Pediatric emergency medicine trisk 3054 3054
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pediatric population, their longer duration may be problematic in assessing the
actual time course for resolution of clinical toxicity and/or in precipitating
prolonged withdrawal symptoms in habituated patients. Nalmefene may be a
useful substitute for prolonged naloxone infusions in cases for which such opioid
antagonism is necessary, but there has been little pediatric experience and there
are few dosing guidelines.
Enhancing Excretion
The best procedures available for enhancing the elimination of an absorbed
poison are multiple-dose activated charcoal, diuresis/urinary alkalinization,
dialysis, and hemoperfusion. Because of the risks, these measures are indicated
only when the patient’s recovery would be otherwise unlikely or in which a
specific significant benefit is expected.
Diuresis/Urinary Alkalinization
Diuresis was historically advocated in poisoning with agents that are excreted
primarily by the renal route. Although it is important to maintain high glomerular
filtration rates in the presence of rhabdomyolysis or when chelating with agents
such as EDTA, forced diuresis has limited value in the treatment of acute
poisoning and has fallen out of favor with the possible exception of mannitol
therapy for ciguatera poisoning.
Ionized diuresis takes advantage of the principle that excretion is favored when
a drug is in its ionized state. Thus, urinary alkalinization promotes excretion of
salicylate (a weak acid). It may also enhance clearance of phenobarbital,
chlorpropamide, and chlorophenoxy herbicides, but in these poisonings, it cannot
be considered a mainstay of therapy. Urine alkalinization can be initiated with
sodium bicarbonate at a dose of 1 to 2 mEq/kg/hr IV over a 1- to 2-hour period,
until such time as the intoxication is resolving. Complications include congestive
heart failure/pulmonary edema and electrolyte abnormalities. Hypokalemia can
interfere with the ability to achieve an alkaline urine pH and should be corrected.
The rate of bicarbonate infusion should be adjusted to maintain a urinary pH of
7.5 to 8.5. Urinary acidification is not indicated because it may lead to serious
side effects such as systemic acidosis and exacerbation of renal impairment in the
context of myoglobinuria.
Multiple-Dose Activated Charcoal (GI Dialysis)
Several studies have shown significant increase in clearance for a number of
drugs when repeated doses of 0.5 to 1 g/kg of activated charcoal are given every 4
