A 74-year-old-man is brought to the emergency department due to confusion. His daughter states that over the past 2 weeks, the patient has been increasingly confused and has decreased oral intake. She shares that he won't stop screaming, "Someone stop the ringing!" He has chronic bilateral osteoarthritis of the knees and hands, hypertension, and chronic kidney disease with a baseline creatinine of 2.2 g/dL. He uses topical methyl salicylate for his arthritis because he does not like taking pills. Temperature is 37.8 C (100 F), blood pressure is 100/60 mm Hg, pulse is 112/min, and respirations are 30/min. Pulse oximetry shows 89% on room air. The patient is awake but disoriented and agitated. Mucous membranes are dry. There is no jugular venous distension. Heart sounds are normal. Lung auscultation reveals bilateral crackles. There is no peripheral edema. Neurological examination is nonfocal. Laboratory results are as follows:
| Serum chemistry | |
| Sodium | 140 mEq/L |
| Potassium | 4.6 mEq/L |
| Chloride | 102 mEq/L |
| Bicarbonate | 14 mEq/L |
| Blood urea nitrogen | 44 mg/dL |
| Creatinine | 2.4 mg/dL |
| Glucose | 85 mg/dL |
What is the most appropriate treatment for this patient's current condition?
Management of salicylate toxicity | |
Activated charcoal |
|
Intravenous sodium bicarbonate |
|
Indications for hemodialysis |
|
This elderly patient's presentation is concerning for salicylate toxicity, likely due to chronic topical salicylate use for osteoarthritis. Salicylate toxicity can lead to hyperpnea, anion gap metabolic acidosis, hyperthermia (dissipated energy byproducts from Krebs cycle dysfunction), tinnitus, confusion, and noncardiogenic pulmonary edema (increased pulmonary vascular permeability).
Salicylate toxicity can be acute or chronic. Chronic toxicity (present in this case) is more common in young children and the elderly; is often not associated with a history of recent, heavy ingestion; and can present with milder symptoms, with only minimally elevated (or even normal) salicylate levels, making the diagnosis very challenging.
Salicylate elimination can be achieved by:
Intravenous sodium bicarbonate therapy: Indicated in symptomatic patients with elevated salicylate levels to alkalinize the urine and serum, thereby increasing salicylate (anion) excretion. However, large volumes are required.
Hemodialysis: Indicated in patients unlikely to tolerate the large volumes of bicarbonate required, such as those with end-stage renal disease, renal failure, and salicylate-induced pulmonary edema (as with this patient). Hemodialysis is also indicated with severe ingestions (eg, shock, seizures), refractory acidosis, or clinical worsening despite sodium bicarbonate therapy.
Activated charcoal is indicated in alert patients within 2 hours of acute ingestion to bind salicylate in the gastrointestinal tract, thereby decreasing its absorption. It would not be appropriate in this patient with altered mental status (aspiration risk) and chronic (rather than acute) toxicity (Choice B).
(Choice A) Although acetazolamide, a carbonic anhydrase inhibitor with diuretic effects, alkalinizes urine, it is contraindicated in patients with salicylate toxicity. It acts by increasing urinary bicarbonate loss, thereby lowering arterial pH, which encourages salicylate diffusion into the CNS, increasing its neurotoxicity.
(Choice C) Glucagon treats hypoglycemia, which occurs with beta-blocker overdose. Hypotension and bradycardia would be expected, and hyperthermia is unusual.
(Choices D and F) Furosemide (used in congestive heart failure) and mannitol (used in cerebral edema) are diuretics. Noncardiogenic pulmonary edema from salicylate toxicity is not due to volume overload. Patients with salicylate toxicity are usually already volume depleted (dry mucous membranes, no jugular venous distension, no peripheral edema) due to vomiting and hyperthermia.
Educational objective:
Characteristics of acute and chronic salicylate toxicity include vomiting, tinnitus, pulmonary edema, hyperthermia, tachypnea, and an anion gap metabolic acidosis. Hemodialysis is indicated in patients with altered mental status, pulmonary edema, renal failure, and persistent acidosis.