A 19-year-old woman is brought to the emergency department by her mother due to suspected drug poisoning. The patient has severe depression treated with fluoxetine and lives with her mother and grandparents. The patient suddenly became ill at home earlier today and developed nausea and vomiting. Her mother suspects the patient may have intentionally ingested a substance to harm herself as her grandparents' medicine cabinet door was found open. On further questioning, the patient states that she swallowed a handful of one of the medications in the cabinet but does not specify further. Her grandparents' medical conditions include anxiety, seasonal allergies, coronary artery disease, and chronic back pain. The patient's mother does not know the specific names and dosages of the medications. Currently, the patient reports nausea and dizziness and has vomited 3 times since arriving at the emergency department. She has smoked a pack of cigarettes daily for the past 5 years and drinks 1 or 2 beers occasionally. She has a history of prior ecstasy use but has no recent use of illicit drugs. Temperature is 38.1 C (100.6 F) , blood pressure is 100/55 mm Hg, pulse is 110/min, and respirations are 28/min. Pulse oximetry shows 99% saturation on ambient air. Examination reveals an awake, agitated young woman with dry mucous membranes. The pupils are 4 mm bilaterally and reactive to light. Heart sounds are normal and the lungs are clear to auscultation. The abdomen is soft, nontender, and nondistended; bowel sounds are normoactive. Motor and sensory deficits are absent, and the patient is fully oriented. A 12-lead ECG shows sinus tachycardia. Chest x-ray reveals clear lung fields and no cardiomegaly. The patient is given intravenous fluids and is placed on continuous ECG monitoring. Laboratory tests are ordered. Laboratory results are as follows:
The results of a urine drug screen are pending.
Item 2 of 2
Which of the following is the most appropriate next step in management of this patient?

Question

A 19-year-old woman is brought to the emergency department by her mother due to suspected drug poisoning. The patient has severe depression treated with fluoxetine and lives with her mother and grandparents. The patient suddenly became ill at home earlier today and developed nausea and vomiting. Her mother suspects the patient may have intentionally ingested a substance to harm herself as her grandparents' medicine cabinet door was found open. On further questioning, the patient states that she swallowed a handful of one of the medications in the cabinet but does not specify further. Her grandparents' medical conditions include anxiety, seasonal allergies, coronary artery disease, and chronic back pain. The patient's mother does not know the specific names and dosages of the medications. Currently, the patient reports nausea and dizziness and has vomited 3 times since arriving at the emergency department. She has smoked a pack of cigarettes daily for the past 5 years and drinks 1 or 2 beers occasionally. She has a history of prior ecstasy use but has no recent use of illicit drugs. Temperature is 38.1 C (100.6 F) , blood pressure is 100/55 mm Hg, pulse is 110/min, and respirations are 28/min. Pulse oximetry shows 99% saturation on ambient air. Examination reveals an awake, agitated young woman with dry mucous membranes. The pupils are 4 mm bilaterally and reactive to light. Heart sounds are normal and the lungs are clear to auscultation. The abdomen is soft, nontender, and nondistended; bowel sounds are normoactive. Motor and sensory deficits are absent, and the patient is fully oriented. A 12-lead ECG shows sinus tachycardia. Chest x-ray reveals clear lung fields and no cardiomegaly. The patient is given intravenous fluids and is placed on continuous ECG monitoring. Laboratory tests are ordered. Laboratory results are as follows:

The results of a urine drug screen are pending.
Item 2 of 2
Which of the following is the most appropriate next step in management of this patient?

Quizplus · Accepted Answer

Explanation: The patient has evidence of a mixed acid-base disorder commonly noted in salicylic acid toxicity: Primary respiratory alkalosis due to activation of medullary respiratory center: High pH of 7.5 with low PaCO₂ of 19 Anion gap (AG) metabolic acidosis due to inhibition of cellular metabolism: AG = (Na − [Cl + HCO₃]) = 26 (normal: 8-14) Metabolic acidosis facilitates proton uptake by the salicylate anion, leading to an uncharged form of salicylic acid. This form can freely pass through electrically neutral cell walls (eg, blood-brain barrier, renal tubules), causing the characteristic toxicities. Therefore, alkalinization of the urine and plasma with sodium bicarbonate is the mainstay of treatment for salicylate toxicity as an alkalotic environment inhibits the protonation process. Patients with an alkalosis should still receive sodium bicarbonate therapy and be closely monitored with frequent arterial blood gases. Other treatments include supplemental glucose (typically given as dextrose 5% water with the bicarbonate solution) to prevent neuroglycopenia (which can occur even in the setting of normal serum glucose), and activated charcoal if presentation is within 2 hours of ingestion. Dialysis is indicated if the patient has pulmonary edema or fluid overload (limiting bicarbonate infusion), altered mental status, renal failure, cerebral edema, severe acidosis, or very high salicylate levels. (Choice A) Atropine is treatment for reversal of cholinergic toxicity as seen in organophosphate exposure from pesticides. These patients classically present with diarrhea, urination, miosis, bradycardia, emesis, lacrimation, and salivation (DUMBELS). Excessive diarrhea may cause hypovolemia leading to acidosis. However, cholinergic toxicity would not be expected to cause a concurrent respiratory alkalosis. (Choice B) Flumazenil is the reversal agent for benzodiazepines. Severe cases of benzodiazepine overdose (eg, intravenous use) could cause a respiratory acidosis (due to respiratory depression), not an alkalosis. (Choice C) Physostigmine may be used as treatment for anticholinergic toxicity although its use is controversial. Anticholinergic toxicity is not expected to cause acute acid-base abnormalities. (Choice D) In patients with salicylate toxicity, sedation and paralysis in preparation for intubation can acutely and quickly worsen acidosis, exacerbating acute toxicity; normal ventilation strategies often cannot mimic the high respiratory rate that was providing a beneficial alkalosis. Therefore, endotracheal intubation should be reserved for those experiencing significant hypoventilation and respiratory failure. Educational objective: Salicylate toxicity presents with a primary respiratory alkalosis often combined with an anion gap metabolic acidosis. Treatment is alkalinization of blood and urine with sodium bicarbonate drip, supplemental glucose, and, if presentation is early (within 2 hours), activated charcoal. Dialysis may be indicated.

A 19-Year-Old Woman Is Brought to the Emergency Department by Her