Toxic ingestions and overdoses US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Toxic ingestions and overdoses. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Toxic ingestions and overdoses US Medical PG Question 1: A 3-year-old boy is brought to the emergency department by his mother for the evaluation of abdominal pain for one hour after drinking a bottle of toilet bowl cleaner. The mother reports that he vomited once on the way to the hospital and his vomit was non-bloody. The patient has pain with swallowing. He appears uncomfortable. Pulse oximetry shows an oxygen saturation of 82%. Examination shows heavy salivation. Oral examination shows mild oral erythema in the area of the epiglottis, but no burns. An x-ray of the chest shows no abnormalities. The patient is admitted to the intensive care unit. He is intubated and oxygenation and intravenous fluid resuscitation are begun. All contaminated clothes are removed. Which of the following is the most appropriate next step in the management of this patient?
- A. Administer activated charcoal
- B. Dilute the ingested agent
- C. Obtain upper endoscopy (Correct Answer)
- D. Perform gastric lavage
- E. Obtain barium upper gastrointestinal series
Toxic ingestions and overdoses Explanation: ***Obtain upper endoscopy***
- An **upper endoscopy** is crucial in evaluating the extent of injury to the **esophagus and stomach** after caustic ingestion.
- This procedure helps in grading the severity of the burn, determining appropriate management, and predicting long-term complications such as **stricture formation**.
*Administer activated charcoal*
- **Activated charcoal** is ineffective in binding **caustic agents** such as acids or alkalis.
- Furthermore, its administration could obscure endoscopic visualization and potentially lead to **aspiration**, which is already a concern in this patient.
*Dilute the ingested agent*
- While dilution might seem intuitive, it can be harmful as it may induce **vomiting**, leading to re-exposure of the esophagus to the caustic agent.
- Dilution can also generate heat, potentially worsening the **thermal injury**.
*Perform gastric lavage*
- **Gastric lavage** is contraindicated in cases of caustic ingestion due to the risk of **perforation** of already damaged tissues.
- It could also induce vomiting and re-expose the esophagus to the caustic substance, increasing the risk of aspiration.
*Obtain barium upper gastrointestinal series*
- A **barium swallow** is not recommended in the acute phase of caustic ingestion due to the risk of **barium extravasation** if there is a perforation.
- It is typically reserved for later evaluation of potential **strictures** once the acute injury has resolved.
Toxic ingestions and overdoses US Medical PG Question 2: A 16-year-old woman is brought to the emergency department by her family for not being responsive. The patient had locked herself in her room for several hours after breaking up with her boyfriend. When her family found her, they were unable to arouse her and immediately took her to the hospital. The patient has a past medical history of anorexia nervosa, which is being treated, chronic pain, and depression. She is not currently taking any medications. The patient has a family history of depression in her mother and grandmother. IV fluids are started, and the patient seems to be less somnolent. Her temperature is 101°F (38.3°C), pulse is 112/min, blood pressure is 90/60 mmHg, respirations are 18/min, and oxygen saturation is 95% on room air. On physical exam, the patient is somnolent and has dilated pupils and demonstrates clonus. She has dry skin and an ultrasound of her bladder reveals 650 mL of urine. The patient is appropriately treated with sodium bicarbonate. Which of the following is the best indicator of the extent of this patient's toxicity?
- A. QRS prolongation (Correct Answer)
- B. QT prolongation
- C. Serum drug level
- D. Anion gap acidosis
- E. Liver enzyme elevation
Toxic ingestions and overdoses Explanation: ***QRS prolongation***
- This patient's symptoms (including **hyperthermia**, **tachycardia**, **hypotension**, **dilated pupils**, **somnolence**, and **clonus**) along with her history of depression suggest **tricyclic antidepressant (TCA) toxicity**.
- **QRS prolongation** on an EKG (greater than 100 ms) is the most reliable indicator of severe TCA toxicity and predicts the risk of **seizures** and **ventricular arrhythmias**.
*QT prolongation*
- While some drugs cause QT prolongation, **TCA toxicity** primarily causes sodium channel blockade leading to **QRS widening**, which is a more critical indicator of immediate cardiotoxicity risk.
- QT prolongation is seen in toxicities involving potassium channel blockade, which is not the primary mechanism of severe TCA cardiotoxicity.
*Serum drug level*
- **Serum drug levels** of TCAs do not reliably correlate with the severity of toxicity due to variable metabolism, protein binding, and individual patient sensitivity.
- Clinical signs and EKG findings are more important in guiding management.
*Anion gap acidosis*
- Although **metabolic acidosis** can occur in severe overdose, it is not specific to TCA toxicity and is a less direct indicator of the immediate cardiotoxic and neurotoxic risk compared to QRS prolongation.
- Anion gap can be elevated due to various reasons in a critically ill patient.
*Liver enzyme elevation*
- **Liver enzyme elevation** is not an immediate or primary indicator of acute TCA overdose severity.
- Liver toxicity can occur with chronic use or some specific drug overdoses, but it is not the most pertinent marker for acute, life-threatening TCA toxicity.
Toxic ingestions and overdoses US Medical PG Question 3: A 36-year-old man is brought to the emergency department by a neighbor with signs of altered mental status. He was found 6 hours ago stumbling through his neighbor's bushes and yelling obscenities. The neighbor helped him home, but found him again 1 hour later slumped over on his driveway in a puddle of vomit. He is oriented to self, but not to place or time. His vitals are as follows: temperature, 36.9°C (98.5°F); pulse, 82/min; respirations, 28/min; and blood pressure, 122/80 mm Hg. Cardiopulmonary examination indicates no abnormalities. He is unable to cooperate for a neurological examination. Physical examination reveals muscle spasms involving his arms and jaw. Laboratory studies show:
Na+ 140 mEq/L
K+ 5.5 mEq/L
CI- 101 mEq/L
HCO3- 9 mEq/L
Urea nitrogen 28 mg/dL
Creatinine 2.3 mg/dL
Glucose 75 mg/dL
Calcium 7.2 mg/dL
Osmolality 320 mOsm/kg
The calculated serum osmolality is 294 mOsm/kg. The arterial blood gas shows a pH of 7.25 and a lactate level of 3.2 mmol/L. Urine examination shows oxalate crystals and the absence of ketones. What is the most appropriate treatment indicated for this patient experiencing apparent substance toxicity?
- A. Ethanol
- B. Hydroxocobalamin
- C. Fomepizole (Correct Answer)
- D. N-acetyl cysteine
- E. Methylene blue
Toxic ingestions and overdoses Explanation: ***Fomepizole***
- **Fomepizole** is indicated for **ethylene glycol** toxicity, which is strongly suggested by the patient's presentation: **high anion gap metabolic acidosis**, increased **osmolal gap**, elevated **creatinine**, and the presence of **oxalate crystals** in the urine.
- It acts by **inhibiting alcohol dehydrogenase**, preventing the metabolism of ethylene glycol to toxic metabolites like glycolic acid and oxalic acid.
*Ethanol*
- **Ethanol** can be used as an antidote for ethylene glycol poisoning, but **fomepizole** is generally preferred due to its more favorable side effect profile and easier dosing.
- It works by competitively inhibiting **alcohol dehydrogenase**, similar to fomepizole, but requires careful monitoring and often causes sedation.
*Hydroxocobalamin*
- **Hydroxocobalamin** is the antidote for **cyanide poisoning**, which typically presents with severe metabolic acidosis, but lacks the characteristic osmolal gap, renal failure, and oxalate crystals seen here.
- It functions by binding to cyanide to form **cyanocobalamin**, which can then be safely excreted.
*N-acetyl cysteine*
- **N-acetyl cysteine (NAC)** is the antidote for **acetaminophen overdose**, which causes liver damage and a different metabolic profile, usually without an osmolal gap or oxalate crystals.
- NAC replenishes **glutathione**, which is essential for detoxifying acetaminophen metabolites.
*Methylene blue*
- **Methylene blue** is used to treat **methemoglobinemia**, a condition typically caused by certain drugs or toxins that leads to impaired oxygen delivery and cyanosis, which is not suggested by the patient's current symptoms or lab results.
- It acts as a **reducing agent** to convert methemoglobin back to hemoglobin.
Toxic ingestions and overdoses US Medical PG Question 4: A 34-year-old woman with a history of depression is brought to the emergency department by her husband 45 minutes after ingesting an unknown amount of a termite poison in a suicide attempt. She has abdominal pain, nausea, and vomiting. Her husband reports that she has had two episodes of watery diarrhea on the way to the emergency department. A distinct, garlic-like odor on the breath is noted on examination. An ECG shows sinus tachycardia and QTc prolongation. Administration of which of the following is most appropriate?
- A. Deferoxamine
- B. Dimercaprol (Correct Answer)
- C. Fomepizole
- D. N-acetylcysteine
- E. Physostigmine
Toxic ingestions and overdoses Explanation: ***Dimercaprol***
- The patient's symptoms (abdominal pain, nausea, vomiting, watery diarrhea, garlic-like odor on breath, QTc prolongation, and ingestion of termite poison) are highly suggestive of **acute arsenic poisoning**.
- **Dimercaprol** (BAL) is a chelating agent indicated for severe arsenic poisoning by forming stable renally excreted complexes with arsenic.
*Deferoxamine*
- Is a chelating agent primarily used for **iron overdose** by binding to free iron in the bloodstream.
- It is not effective for arsenic poisoning and would not address the patient's specific symptoms.
*Fomepizole*
- Is an **alcohol dehydrogenase inhibitor** used in cases of **methanol** or **ethylene glycol poisoning** to prevent the formation of toxic metabolites.
- It has no role in the management of arsenic poisoning due to a different mechanism of toxicity.
*N-acetylcysteine*
- Is an antidote primarily used for **acetaminophen overdose** by replenishing glutathione stores, and as a mucolytic.
- It is not indicated for arsenic poisoning and would not mitigate the toxic effects of arsenic.
*Physostigmine*
- Is an **acetylcholinesterase inhibitor** used to reverse anticholinergic toxicity.
- The patient's symptoms are not consistent with anticholinergic poisoning, and physostigmine would be inappropriate and potentially harmful.
Toxic ingestions and overdoses US Medical PG Question 5: A 6-year-old boy is brought to the emergency department 12 hours after ingesting multiple pills. The patient complains of noise in both his ears for the past 10 hours. The patient’s vital signs are as follows: pulse rate, 136/min; respirations, 39/min; and blood pressure, 108/72 mm Hg. The physical examination reveals diaphoresis. The serum laboratory parameters are as follows:
Na+ 136 mEq/L
Cl- 99 mEq/L
Arterial blood gas analysis under room air indicates the following results:
pH 7.39
PaCO2 25 mm HG
HCO3- 15 mEq/L
Which of the following is the most appropriate first step in the management of this patient?
- A. Hemodialysis
- B. Supportive care
- C. Gastrointestinal decontamination
- D. Urine alkalinization (Correct Answer)
- E. Multiple-dose activated charcoal
Toxic ingestions and overdoses Explanation: ***Urine alkalinization***
- This patient likely has **salicylate toxicity** (suggested by **tinnitus**, hyperpnea leading to **respiratory alkalosis** followed by **metabolic acidosis**, and diaphoresis), for which **urine alkalinization** is a primary treatment.
- Making the urine alkaline helps to **ionize salicylates**, trapping them in the renal tubules and increasing their renal excretion.
*Hemodialysis*
- **Hemodialysis** is reserved for severe salicylate toxicity, such as refractory acidosis, severe central nervous system effects, renal failure, or very high salicylate levels, not as a first step.
- While it can remove salicylates, less invasive and effective options like urine alkalinization should be attempted first.
*Supportive care*
- While essential, **supportive care** alone (e.g., maintaining hydration, monitoring vital signs) is not sufficient for active management of significant salicylate overdose.
- It does not address the underlying toxicology, which requires specific interventions to enhance drug elimination.
*Gastrointestinal decontamination*
- **Single-dose activated charcoal** would be indicated if the ingestion was within 1-2 hours, but 12 hours have passed, making it less effective.
- Other GI decontamination methods like **gastric lavage** are rarely indicated and generally not recommended beyond 1 hour post-ingestion due to risks versus benefits.
*Multiple-dose activated charcoal*
- **Multiple-dose activated charcoal (MDAC)** is used for drugs that undergo enterohepatic recirculation or have delayed absorption, but its efficacy in salicylate poisoning, especially 12 hours post-ingestion, is debated and not a first-line intervention.
- Urine alkalinization is a more direct and effective method for accelerating salicylate elimination from the body.
Toxic ingestions and overdoses US Medical PG Question 6: A 3-year-old boy is brought in by his parents to the emergency department for lethargy and vomiting. The patient was fine until this afternoon, when his parents found him in the garage with an unlabeled open bottle containing an odorless liquid. On exam, the patient is not alert or oriented, but is responsive to touch and pain. The patient is afebrile and pulse is 90/min, blood pressure is 100/60 mmHg, and respirations are 20/min. Which of the following is an antidote for the most likely cause of this patient’s presentation?
- A. Glucagon
- B. Epinephrine
- C. Fomepizole (Correct Answer)
- D. Succimer
- E. Sodium bicarbonate
Toxic ingestions and overdoses Explanation: ***Fomepizole***
- The patient's presentation with **lethargy**, **vomiting**, and altered mental status after unsupervised access to an **unlabeled, odorless liquid** highly suggests **toxic alcohol ingestion** (e.g., ethylene glycol or methanol).
- **Fomepizole** is a competitive inhibitor of **alcohol dehydrogenase**, preventing the metabolism of toxic alcohols into their highly toxic acid metabolites (oxalic acid, formic acid), thus reducing organ damage.
*Glucagon*
- **Glucagon** is primarily used to treat severe **hypoglycemia**, especially in patients who cannot tolerate oral glucose or if intravenous access is difficult.
- It is also indicated in the management of **beta-blocker overdose** to bypass beta-adrenergic receptors and increase cardiac contractility.
*Epinephrine*
- **Epinephrine** is a potent **vasopressor** and bronchodilator used in emergencies such as **anaphylaxis**, **cardiac arrest**, and severe asthma exacerbations.
- It works by stimulating alpha- and beta-adrenergic receptors, leading to vasoconstriction, increased heart rate, and bronchodilation.
*Succimer*
- **Succimer** is a **chelating agent** primarily used in the treatment of **lead poisoning** in children with blood lead levels above a certain threshold.
- It binds to lead ions, forming a stable complex that can be excreted in the urine.
*Sodium bicarbonate*
- **Sodium bicarbonate** is used to correct **metabolic acidosis**, which can occur in various conditions, including severe sepsis, diabetic ketoacidosis, and certain poisonings (e.g., salicylates, tricyclic antidepressants).
- While toxic alcohol ingestion can cause metabolic acidosis, sodium bicarbonate addresses the acidosis itself, not the underlying toxic alcohol metabolism, for which fomepizole is the specific antidote.
Toxic ingestions and overdoses US Medical PG Question 7: A 64-year-old man is brought to the emergency department by his wife with a 2-hour history of diarrhea and vomiting. He says that he felt fine in the morning, but noticed that he was salivating, sweating, and feeling nauseated on the way home from his work as a landscaper. The diarrhea and vomiting then started about 10 minutes after he got home. His past medical history is significant for depression and drug abuse. His wife says that he has also been more confused lately and is afraid he may have ingested something unusual. Physical exam reveals miosis, rhinorrhea, wheezing, and tongue fasciculations. Which of the following treatments would most likely be effective for this patient?
- A. Sodium bicarbonate
- B. Naloxone
- C. Atropine (Correct Answer)
- D. Fomepizole
- E. Ammonium chloride
Toxic ingestions and overdoses Explanation: ***Atropine***
- This patient displays classic signs of **organophosphate poisoning**, characterized by **cholinergic crisis** (salivation, sweating, nausea, vomiting, diarrhea, miosis, rhinorrhea, wheezing, fasciculations). **Atropine** is a competitive antagonist of acetylcholine at muscarinic receptors and is the primary antidote, reversing most of these symptoms.
- The patient's profession as a **landscaper** increases his exposure risk, and the acute onset of symptoms supports a toxic exposure rather than an infection.
*Sodium bicarbonate*
- **Sodium bicarbonate** is primarily used to treat **metabolic acidosis**, such as in aspirin overdose or tricyclic antidepressant poisoning, or to alkalinize urine in certain toxic exposures.
- While metabolic acidosis can occur in severe organophosphate poisoning, it is not the primary treatment for the **cholinergic symptoms** themselves.
*Naloxone*
- **Naloxone** is an opioid antagonist used to reverse the effects of **opioid overdose**, characterized by respiratory depression, miosis, and central nervous system depression.
- The patient's symptoms of excessive secretions, gastrointestinal distress, and muscle fasciculations are inconsistent with opioid overdose.
*Fomepizole*
- **Fomepizole** is an alcohol dehydrogenase inhibitor used to treat **methanol and ethylene glycol poisoning**.
- These poisonings present with severe metabolic acidosis, visual disturbances (methanol), or renal failure (ethylene glycol), which are not the primary features described in this patient.
*Ammonium chloride*
- **Ammonium chloride** is an acidifying agent used to treat severe **metabolic alkalosis** or to increase the excretion of basic drugs.
- It is not indicated for the treatment of organophosphate poisoning and would likely exacerbate any existing acidosis.
Toxic ingestions and overdoses US Medical PG Question 8: A 67-year-old man presents to the emergency department acutely confused. The patient's wife found him mumbling incoherently in the kitchen this morning as they were preparing for a hike. The patient was previously healthy and only had a history of mild forgetfulness, depression, asthma, and seasonal allergies. His temperature is 98.5°F (36.9°C), blood pressure is 122/62 mmHg, pulse is 119/min, and oxygen saturation is 98% on room air. The patient is answering questions inappropriately and seems confused. Physical exam is notable for warm, flushed, and dry skin. The patient's pupils are dilated. Which of the following is also likely to be found in this patient?
- A. Hypoventilation
- B. QRS widening
- C. Coronary artery vasospasm
- D. Increased bronchial secretions
- E. Urinary retention (Correct Answer)
Toxic ingestions and overdoses Explanation: ***Urinary retention***
- The patient's symptoms (dilated pupils, warm/flushed/dry skin, confusion, tachycardia) are consistent with **anticholinergic toxidrome**.
- **Urinary retention** is a common manifestation of anticholinergic toxicity due to the paralysis of the detrusor muscle and contraction of the urethral sphincter.
*Hypoventilation*
- Anticholinergic toxicity typically causes **tachycardia** and may lead to tachypnea, not hypoventilation.
- Respiratory depression is more characteristic of **opioid** or **sedative-hypnotic** overdose.
*QRS widening*
- **QRS widening** is characteristic of **sodium channel blockade**, as seen with tricyclic antidepressant overdose, which can have anticholinergic effects but primarily causes cardiac toxicity via sodium channel blockade.
- While anticholinergics can cause arrhythmias, QRS widening specific to this mechanism isn't a primary feature of pure anticholinergic toxidrome.
*Coronary artery vasospasm*
- **Coronary artery vasospasm** is not a direct effect of anticholinergic toxicity.
- It is more commonly associated with drug use such as **cocaine**, or certain medications like **5-fluorouracil**.
*Increased bronchial secretions*
- Anticholinergic agents **decrease bronchial secretions** by blocking muscarinic receptors in the airway smooth muscle and glands.
- Increased bronchial secretions are characteristic of **cholinergic overdose**.
Toxic ingestions and overdoses US Medical PG Question 9: A 25-year-old woman is brought to the emergency department 12 hours after ingesting 30 tablets of an unknown drug in a suicide attempt. The tablets belonged to her father, who has a chronic heart condition. She has had nausea and vomiting. She also reports blurring and yellowing of her vision. Her temperature is 36.7°C (98°F), pulse is 51/min, and blood pressure is 108/71 mm Hg. Abdominal examination shows diffuse tenderness with no guarding or rebound. Bowel sounds are normal. An ECG shows prolonged PR-intervals and flattened T-waves. Further evaluation is most likely to show which of the following electrolyte abnormalities?
- A. Increased serum K+ (Correct Answer)
- B. Decreased serum K+
- C. Decreased serum Na+
- D. Increased serum Na+
- E. Increased serum Ca2+
Toxic ingestions and overdoses Explanation: ***Increased serum K+***
- The patient presents with classic symptoms of **digoxin toxicity**, including **nausea, vomiting, blurry and yellow vision, bradycardia**, and ECG changes like **prolonged PR interval** and **flattened T-waves**.
- **Digoxin inhibits the Na+/K+-ATPase pump**, leading to an increase in extracellular potassium as potassium cannot enter the cells.
*Decreased serum K+*
- While hypokalemia can exacerbate digoxin toxicity by increasing digoxin binding to the Na+/K+-ATPase, digoxin overdose itself typically causes **hyperkalemia** due to its direct effect on the pump.
- ECG changes like **flattened T-waves** can be seen in hypokalemia, but the overall clinical picture, especially the history of overdose and bradycardia, points more strongly to digoxin toxicity with hyperkalemia.
*Decreased serum Na+*
- **Hyponatremia** is not a characteristic feature of acute digoxin overdose.
- Digoxin primarily affects potassium and calcium channels, with less direct impact on sodium levels, unless related to fluid status changes which are not indicated here.
*Increased serum Na+*
- **Hypernatremia** is not typically associated with digoxin toxicity.
- Digoxin's mechanism of action does not directly lead to increased serum sodium; rather, it primarily inhibits the Na+/K+-ATPase.
*Increased serum Ca2+*
- Digoxin **increases intracellular calcium** by inhibiting the Na+/K+-ATPase, which indirectly leads to increased Na+/Ca2+ exchanger activity.
- However, this primarily affects intracellular levels and **does not typically result in increased serum calcium**.
Toxic ingestions and overdoses US Medical PG Question 10: For evaluating the functioning of a health center, which is the most important determinant for assessing clinical management?
- A. Structure
- B. Input
- C. Process (Correct Answer)
- D. Outcome
- E. Output
Toxic ingestions and overdoses Explanation: ***Process***
- Evaluating the **process** involves assessing the actual delivery of care, including adherence to clinical guidelines, patient-provider interactions, and the timeliness and appropriateness of services. This directly reflects the quality of **clinical management**.
- It focuses on *how* care is provided, which is crucial for identifying areas of strength and weakness in the day-to-day operations of a health center's clinical functions.
*Structure*
- **Structure** refers to the resources and settings in which care is provided, such as facilities, equipment, staff qualifications, and organizational policies.
- While important, a good structure does not guarantee good clinical management; the structure offers the potential for quality, but the actual delivery of care (process) is what matters most for assessment.
*Input*
- **Input** is a broad term often overlapping with structure, referring to the resources poured into the system like funding, staff, and materials.
- Like structure, input provides the necessary components, but evaluating them alone does not directly assess the *effectiveness* or *quality* of clinical management.
*Output*
- **Output** refers to the immediate results of service delivery, such as the number of patients seen, procedures performed, or services rendered.
- While outputs can be measured, they represent quantity rather than quality and do not directly assess the appropriateness or effectiveness of clinical management itself.
*Outcome*
- **Outcome** measures the end results of care, such as patient health status, satisfaction, or mortality rates.
- While outcomes are critical, they are often influenced by many factors beyond direct clinical management (e.g., patient adherence, social determinants of health) and may not immediately reflect the quality of the *process* of care delivery itself.
More Toxic ingestions and overdoses US Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
