Salicylate Overdose Flashcards
(13 cards)
In toxic doses of salicylates what causes the clinical manifestations? (Pathophys - simplified)
Direct stimulation of respiratory center —> Hyperventilation and respiratory alkalosis (remember this is not just compensation for the metabolic acidosis)
Stimulation of chemoreceptor trigger zone —> vomiting
Uncoupling of oxidative phosphorylation —> anaerobic metabolism and thus AG metabolic acidosis, hyperthermia
Ototoxicity —> tinnitus and reversible hearing loss
Alterations in capillary integrity —> cerebral edema and pulmonary edema
Describe the half life of salicylates at therapeutic levels and in overdoses
At therapeutic levels: half-life is 2-4 hours
Toxic concentrations: half-life is up to 20 hours
At what serum level are signs/symptoms of toxicity typically seen in salicylate overdoses?
> 30 mg/dL
How long does it take for peak serum concentrations of salicylate to be reached in salicylate overdose?
Up to 4-6 hours
That is why it is important to get patient’s admitted even for mild increases in salicylate levels.
How does the acid-base disturbances caused by salicylate overdose differ in children from adults?
Children will often not have the initial respiratory alkalosis
What should you be HIGHLY suspicious of in a patient with salicylate overdose who has a respiratory ACIDOSIS?
Pulmonary edema
Because the mixed disorder of respiratory ALKALOSIS and metabolic acidosis is so common in adults that if you have a respiratory acidosis this almost certainly means that they have acute lung injury
How does chronic overdose of salicylates present as compared to acute overdoses?
Symptoms similar: N/V, tinnitus, hearing loss, lethargy, hyperventilation, diaphoresis, etc. Metabolic acidosis, pulm edema, CV collapse etc. BUT slower in onset and less specific.
Often patient’s are elderly (because more likely to be on chronic ASA therapy) with confusion, hallucinations, agitation, dehydration, and metabolic acidosis.
These clinical clues should cause you to maintain a high index of suspicion for salicylate overdose
Unexplained respiratory alkalosis
Metabolic acidosis or mixed acid-base disorders
Elderly patient with AMS (think chronic toxicity)
Patients with hearing complaints
These complications from salicylate overdose are more common in chronic overdose than acute overdose
Pulmonary edema, cerebral edema, seizures, renal failure
If you intubate someone with salicylate toxicity how should you manage their ventilation?
HYPERVENTILATE them in order to match their preintubation PCO2!
You should really try to avoid intubation as much as possible in salicylate poisoned patients because it is difficult to keep up with the respiratory rate that they need
Mainstay of therapy for salicylate overdose in mild-moderate cases
Sodium Bicarbonate to cause urinary alkalinization
Goal urine pH: 7.5-8.0
What electrolyte disturbance commonly occurs with salicylate overdose and why is it important to correct it?
HYPOKALEMIA - because potassium moves into cells in exchange for H ions in the presence of alkalemia.
Urinary alkalinization will not occur unless Hypokalemia is corrected
Indications for hemodialysis in salicylate overdoses
Acute OD with serum level >100 Chronic OD with serum level >60 Altered mental status/coma Increasing levels despite treatment Worsening clinical status despite treatment Pulmonary or cerebral edema Renal Failure Seizures Severe acid-base disturbance
