Toxins Flashcards
Salicylate toxicity phases? Treatment?
Salicylate toxicity is unique in that it leads to 2 acid-base disturbance mechanisms. Symptoms of salicylate toxicity include nausea, vomiting, abdominal pain, lethargy, tinnitus, dizziness, hyperthermia, tachypnea, hypokalemia, hypoglycemia, altered mental status, seizure, cerebral edema, and coma. There are 3 phases to salicylate toxicity:
Phase 1: Hyperventilation resulting from direct respiratory center stimulation leading to respiratory alkalosis and compensatory alkaluria. Potassium and sodium bicarbonate are excreted in the urine. This phase may last up to 12 hours.
Phase 2: Paradoxic aciduria in the presence of continued respiratory alkalosis because potassium has been lost from the kidneys. This phase begins within hours and may last 12 to 24 hours.
Phase 3: Dehydration, hypokalemia, and progressive metabolic acidosis. This begins 4 to 6 hours after ingestion in a young infant or 24 hours or more after ingestion in an adolescent or adult.
In an acute salicylate overdose that presents shortly after ingestion, gastric lavage and activated charcoal are the appropriate initial management. Because this patient is presenting with symptoms of tinnitus and confusion, it is likely that he has already digested the toxic substance. There is also an unknown amount of time since ingestion. Once the medication has already been digested, intensive supportive care, electrolyte imbalance correction, and correction of the acid-base derangements are the main form of treatment of this condition. Sodium bicarbonate is often used to alkalinize the urine, which increases the rate of elimination. In severe cases, hemodialysis is also used.
Atropine toxicity look out for?
Atropine is a muscarinic antagonist and is used as first-line pharmacotherapy for symptomatic bradycardia according to the Advanced Cardiac Life Support algorithm. The recommended atropine dose for bradycardia is 0.5 mg; however, this patient accidentally was administered 5 mg of atropine, causing anticholinergic toxicity.
Systemically, high doses of anticholinergics can cause confusion, constipation, urinary retention, fever, flushing, tachycardia, blurred vision, and mydriasis. Mydriasis is seen because the action of acetylcholine is blocked in postsynaptic receptors, resulting in paralysis of the iris sphincter and ciliary muscle. This allows unopposed action of the iris dilator and lack of accommodation, respectively. When examining these patients, physicians find a fixed and dilated pupil that is similar to that shown in the exhibit below.
how do we manage severe methanol or ethylene glycol ingestion?
In the setting of severe methanol or ethylene glycol ingestion with high anion gap metabolic acidosis or evidence of end-organ dysfunction, the most appropriate next step in management is the initiation of immediate hemodialysis which will rapidly remove both the toxic acid metabolites and parent alcohols and restore the appropriate acid-base balance.
