Poisoning

A 27 year old woman is brought into the emergency department by her roommate 30 minutes after ingesting a bottle of aspirin in a suicide attempt. Which of the following acid-base disorders is most likely to be present in this patient? A. Respiratory alkalosis due to stimulation of the respiratory center and increased CO2 production B. Primary respiratory acidosis with compensatory metabolic alkalosis C. Primary metabolic acidosis with compensatory respiratory alkalosis D. Respiratory acidosis due to somnolence causing decreased respiratory drive

The answer is A. Aspirin, a salicylate, directly stimulates the medullary chemoreceptor trigger zone and respiratory center, leading to increased CO2 production and increased respiratory rate, causing a primary respiratory alkalosis. A primary metabolic acidosis typically develops as well. Salicylates are absorbed from the stomach and bowel wall and typically have onset of action within 30 minutes.

A 45 year-old is brought in 8 hours after a large overdose of his lithium. What is the best treatment method for this overdose? A. Hemodialysis B. Gastric lavage C. Whole bowel irrigation D. Activated charcoal

The answer is A. Dehydration, over-diuresis, and drug-drug interaction (particularly NSAIDs) are common precipitants of lithium toxicity in the patient chronically taking lithium. In general, the clinical condition, not drug level, should guide therapy. In acute ingestions in particular, lithium levels do not correlate well with symptoms or prognosis. Charcoal does not bind heavy metals like lithium. Hemodialysis is helpful in lithium toxicity.

For which of the following cases (all of which are characterized by an ingestion history known with certainty) is gastric lavage most likely indicated? A. Adult patient, nortriptyline ingestion (50 mg/tab x 100 tablets, 45 minutes PTA) B. Adult patient, ibuprofen ingestion (800 mg/tab x 5 tabs, 20 minutes prior to arrival (PTA) in the ED C. Adult patient, kerosene ingestion (8 oz, 20 minutes PTA) D. Adult patient, metoprolol ingestion (100 mg/tab x 100 tablets, 6 hours PTA)

The answer is A. Gastric lavage (GL) is generally not effective if performed more than a few hours (exact time ranges depend on clinical circumstances) after ingestion. Due to risks of lavage (aspiration, gastric/esophageal perforation), trivial ingestions are not an indication for GL. Due to the risk of aspiration with hydrocarbons and further injury with caustic ingestions, GL is contraindicated for hydrocarbon and caustic ingestions.

A 25 year old presents with an ingestion of acetaminophen 2 hours prior to arrival. Which of the following statements is TRUE? A. Activated charcoal is indicated to treat this ingestion B. AST of 32 and ALT of 27 from arrival labs indicate the absence of hepatotoxicity from this ingestion. C. An acetaminophen level of 84 mg/dl from arrival labs necessitates use of n-acetylcysteine D. Acetaminophen toxicity is predicted to occur at a dose of 20 mg/kg.

The answer is A. NAPQI -- the prime toxic mediator -- builds up when glutathione stores deplete and thus causes hepatotoxicity. The first stage of acetaminophen toxicity is largely asymptomatic. The toxic acetaminophen dose, when a single ingestion of nonsustained-release preparation is taken, is about 140 mg/kg. Therapy is guided by the Rumack-Matthew nomogram, provided the ingestion is an acute one involving nonsustained-release preparations. The antidote, N-acetylcysteine, prevents toxicity by inhibiting the binding of NAPQI to hepatocytes.

The clinical presentation of clonidine toxicity most closely mimics toxicity from which of the following classes of medication? A. Opioids B. Stimulants C. Cholinergics D. Beta blockers

The answer is A. The hallmark signs and symptoms of clonidine toxicity include:hypotension, bradycardia, mental status change, respiratory depression, and miosis. The presentation very closely mimics opioid toxicity.

A 2 year old child presents with an overdose of her mother's iron containing multivitamins. What antidote should you consider for iron toxicity? A. Glucagon B. Deferoxamine C. Pyridoxine D. Methylene blue

The answer is B. Deferoxamine binds directly to free iron and thus is the antidote for iron toxicity. It is given intramuscularly or intravenously and often causes the patient's urine to turn color (vin rosé urine). Methylene blue is an antidote for methemoglobinemia. N-acetylcysteine is the antidote for acetaminophen. Pyridoxine is the antidote for isoniazid toxicity and glucagon can serve as an antidote for beta blocker, calcium channel blocker, or insulin overdoses.

A 55 year-old man is brought down from the outpatient procedures clinic after becoming severely short of breath during an endoscopy under light sedation. His pulse oximeter is reading 100% on a non-rebreather mask. You notice an interesting discoloration of his blood when it is drawn. What antidote should be administered? A. Amyl nitrite B. Methylene blue C. Deferoxamine D. Hydroxycobalamin

The answer is B. Nitrates/nitrites, local anesthetics, dapsone, and phenazopyridine are the common causes of methemoglobinemia. Methemoglobinemia causes the oxygen dissociation curve to shift to the left, making the remaining hemoglobin less likely to give up oxygen to the tissues. Blood from patients with methemoglobinemia is a chocolate brown color. Methylene blue is the antidote. Pulse oximetry is unreliable in patients with methemoglobinemia, since the pulse oximeter cannot differentiate oxyhemoglobin from methemoglobinemia.

A young woman presents with an amitriptyline overdose. She is agitated and confused. In overdoses of this class of medications, an indicator of severe toxicity would include A. Metabolic acidosis with a pH < 7.25 B. Prolonged QRS interval C. Serum amitriptyline level > 200 mcg/dl D. Elevated osmolar gap > 20

The answer is B. Sodium channel blockade is one of the major means by which tricyclic antidepressants (TCAs) exert their toxicity. Sodium channel blockade is responsible for the prolongation of phase 0 of the cardiac action potential. As a result, patients with TCA toxicity develop prolongation of the PR and QRS intervals on the EKG. Other pharmacologic actions of TCAs include: GABA-A antagonism, inhibition of amine (NE, 5-HT) reuptake, alpha-adrenergic blockade, and anti-muscarinic/anti-histaminic effects.

A teenager presents one hour after ingesting a "handful" of acetaminophen tablets. Which of the following statements is TRUE? A. Serial liver function tests are indicated in all acetaminophen ingestions. B. Renal sequelae are expected. C. An acetaminophen level drawn at hour four dictates need for antidotal therapy. D. The intravenous formulation of N-acetylcysteine is safer than oral N-acetylcysteine.

The answer is C. An acetaminophen level drawn at hours 4-20 can be plotted on the Rumack-Matthew nomogram to guide therapy based on the potential for hepatic (not renal) toxicity. Liver function tests are not indicated for trivial acetaminophen ingestions, but may be useful in severe ingestions. Charcoal binds acetaminophen and should be given early. N-acetylcysteine (NAC), the antidote, is only FDA-approved in the United States for oral use, although IV NAC has been used safely for years in other countries. One side-effect of the IV preparation is anaphylactoid reaction.

A 26 year-old presents with agitation, chest pain and a heart rate of 142 bpm after intranasal cocaine use. The EKG is normal except for sinus tachycardia. What is the best medication to use in this situation? A. Diphenhydramine B. Esmolol C. Lorazepam D. Haloperidol

The answer is C. Benzodiazepines are the treatment mainstay for cocaine toxicity. Lorazepam and diazepam can be titrated to treat the symptoms of agitation and increased adrenergic tone common to patients with cocaine toxicity. Beta blockers should not be administered due to a potential for unopposed alpha-adreneric stimulation and resultant hypertension. Haloperidol and diphenhydramine can contribute to the hyperthermia common to patients with cocaine toxicity.

Parents bring in their 13 year old girl two hours after she ingested a large amount of Acetaminophen in suicide attempt. She tearfully refuses to drink the activated charcoal. Which of the following is TRUE regarding your ability to administer the charcoal? A. You must get parental permission prior to treating her B. A court injunction is needed to force her to drink the charcoal C. A nasogastric tube may be placed to facilitate treatment D. You cannot force her to take the charcoal

The answer is C. Charcoal aspiration does carry with it the risk of developing a severe pneumonitis. If necessary, an uncooperative or combative patient may need to be intubated in order to safely deliver the charcoal with the airway secured. Suicidal patients do not have the right to refuse care, and physicians may do what they need to do in an effort to save the patient. In emergencies, parental permission for treatment is unnecessary.

A 3 year old girl presents after accidentally ingesting an alkali drain cleaner. Which of the following statements regarding her management is true? A. Neutralization therapy using a strong acid is warranted B. Activated charcoal should be administered C. Endoscopy is useful in the assessment of injury D. Gastric lavage should be performed immediately to reduce gastric injury

The answer is C. Gastric lavage and ipecac therapy are contraindicated due to concern regarding recurrent injury to the esophagus from a second contact with the caustic ingestant. Activated charcoal is contraindicated because it obscures endoscopic assessment (and doesn't work at binding caustics). Neutralization with milk or water may be indicated in caustic ingestions without perforation, but strong acids/alkali should not be used. Endoscopic assessment should be performed early as the risk of procedurally-induced perforation increases with delayed endoscopy.

Severe lead toxicity can commonly result in which of the following clinical symptoms A. Dermatitis B. Stocking glove peripheral neuropathy C. Memory loss D. Constipation

The answer is C. Lead toxicity affects a variety of systems. The central nervous system effects are many and range from encephalopathy and seizure to sleep disturbance and memory deficits. The peripheral nervous system can also be involved, with paresthesias and wrist drop being common. Colicky abdominal pain is often present. While dermatitis is not common in lead poisoning, you can see bluish lead lines on the gingiva.

A 17 year-old has presented after taking a large amount of nortriptyline prescribed for migraine prophylaxis. Clinically, you take care of stabilizing her and initiate appropriate treatment. After reviewing reference materials you calculate that she has taken a potentially lethal dose of this tricyclic antidepressant. Which of the following would you expect to see on her electrocardiogram? A. Right bundle branch block B. Compacted QT intervals C. Prolonged QRS intervals D. Prolonged PR intervals

The answer is C. Tricyclic antidepressant (TCA) toxicity can result in the following EKG abnormalities: sinus tachycardia (through antimuscarinic activity), prolongation of any of the EKG intervals (through sodium and potassium channel blockade), ventricular dysrhythmias (sodium channel blockade), and right axis deviation of the terminal 40 ms of the QRS complex (sodium channel blockade).

An 84 year-old with a history of congestive heart failure is brought in by his family for vomiting and diarrhea. He also complains that things "have weird colors". He has been having odd palpitations but cannot describe them further. His family expresses their concern that he has not been taking his medications correctly. Given his presenting symptoms, which medication are you most concerned about? A. Metoprolol B. Amiodarone C. Diphenhydramine D. Digoxin

The answer is D. Digoxin toxicity classically presents as weakness, fatigue, nausea/vomiting/diarrhea, confusion, and a visual disturbance hallmarked by yellow/green halos around objects.

A mother brings in her 4 year old child who was happily eating "blackberries" from weeds in the garden and is now acting strangely. She has identified them as Belladonna from a quick internet search. Which physical examination finding might you also expect to find in this child? A. Urinary incontinence B. Diaphoresis C. Miosis D. Flushed skin

The answer is D. The classic presentation of anticholinergic toxicity is best remembered by the following: hot as Hades; blind as a bat; dry as a bone; red as a beet; mad as a hatter. Patients with anticholinergic toxicity are flushed, warm, psychotic, mydriatic, and dry. Bowel sounds are classically hypoactive.

During opiate withdrawal which of the following symptoms would you expect to find? A. Pruritis B. Constipation C. Urinary retention D. Tachypnea

The answer is D. Withdrawal syndromes tend to have symptoms that are the reverse of intoxication syndromes. In opiate withdrawal, individuals present with CNS excitation, diarrhea, mydriasis, tachypnea and often abdominal cramping and vomiting. While uncomfortable, opiate withdrawal is not life threatening and is managed symptomatically

A 72 year-old presents with an intentional overdose of a bottle of aspirin about 3 hours prior to presentation in the ED. Which of the following arterial blood gas results would you expect to come from this patient? A. pH 7.33 pCO2 48 pO2 58 HCO3 29 B. pH 7.45 pCO2 21 pO2 124 HCO3 14 C. pH 7.47 pCO2 31 pO2 96 HCO3 25 D. pH 7.14 pCO2 68 pO2 102 HCO3 23

The answer is B. Acute salicylate overdose characteristically causes a metabolic acidosis mixed with a respiratory alkalosis.

For which of the following cases is activated charcoal therapy most appropriate? A. Acetaminophen overdose B. Lithium overdose C. Drain cleaner ingestion D. Iron supplement overdose

Charcoal acts by adhering to most toxins, impairing toxin absorption, and enhancing elimination. Some toxins (i.e., heavy metals such as lithium, lead, and iron) do not bind to charcoal. Consequently, charcoal is not indicated in isolated heavy metal injections. Also, charcoal is contraindicated in patients with unprotected airways (risk of aspiration) and in caustic ingestions as the black color of the charcoal interferes with the endoscopic evaluation that often follows caustic ingestion. In addition, a caustic ingestion such as alkaline drain cleaner causes its damage by direct contact rather than absorption so charcoal will not be effective.

A 42 year-old woman presents with an overdose of her Xanax (alprazolam) that her family indicates she has been taking for years to help with her anxiety. The bottle indicates that the prescription was filled yesterday with 90 pills and is now empty. The patient is minimally responsive to painful stimuli and does not react when you suction secretions out of her posterior pharynx. What is your next management step? A. Administration of narcan B. Administration of flumazenil C. Intubation for airway support D. Close observation

The answer is C. Isolated benzodiazepine (BZD) OD is generally quite benign. When taken in combination with other agents, however, BZDs can cause significant morbidity and mortality. Patients with BZD OD commonly present with oversedation. A paradoxical excitation syndrome can occur but is uncommon. While an antidote (flumazenil) exists, supportive care is the key to treatment. Flumazenil, a BZD antagonist, can cause seizures in patients taking BZDs chronically by inducing an acute BZD withdrawal syndrome. It is best used in reversal of BZD-induced iatrogenic oversedation. Here, however, physicians must take heed as the half-life is short and resedation can occur.

With which of the following substances is acute withdrawal most likely life-threatening? A. Heroin B. Ethanol C. Lithium D. Cocaine

Belladonna is also known as deadly nightshade and contains chemical compounds with strong anticholinergic properties. The classic presentation of anticholinergic toxicity is often describes as Hot as Hades; blind as a bat; dry as a bone; red as a beed; mad as a hatter. Patients with anticholinergic toxicity are flushed, warm, psychotic, mydriatic and dry. Bowel sounds are classically hypoactive and they often have urinary retention.

A 19 year old presents with bizarre behavior and a friend admits to use of PCP. What ocular findings would you expect? A. Nystagmus B. Afferent pupillary defect C. Monocular diplopia D. Mydriasis

The answer is A. A patient with classic PCP intoxication presents with dramatic multidirectional nystagmus, hypertension, and bizarre behavior.

A patient presents after an unknown ingestion. Her initial electrocardiogram (EKG) is shown below (sinus tachy, long interval) Based on the EKG, an overdose with which of the following medications would be most likely? A. Amitriptyline B. Nifedipine C. Clonidine D. Ibuprofen

The answer is A. Amitriptyline is a tricyclic antidepressant (TCA). As such, it has anticholinergic activity that will cause a sinus tachycardia. Additional EKG findings with TCA toxicity include interval prolongation and terminal 40 ms right axis deviation. Clonidine, nifedipine, and metoprolol typically cause bradycardia. NSAIDs, like ibuprofen, rarely affect the heart rate.

A 23 year old woman is dropped off by her boyfriend after an unknown overdose. You notice that she is has very large pupils and is sweating profusely. Her respiratory rate, blood pressure and heart rate are elevated. Which of the following is the most likely agent to have caused her symptoms? A. Jimson weed B. Cocaine C. Heroin D. Insulin

Cocaine is a sympathomimetic. Sympathomimetics and anticholinergics such as Jimson Weed can be differentiated by the presence of sweating although both can cause delirium and mydriasis. Aspirin or salicyclate toxicity can cause increased respiratory drive through direct stimulation of the medullary respiratory center but should not cause papillary changes. Heroin will result in a classic toxidrome of miosis, CNS and respiratory depression as will other opiates.