Poisoning and Toxidromes — MCQs
A farmer with pinpoint pupils, increased secretions and urination. What is the most likely diagnosis?
What is the antidote for acetaminophen overdose?
The antidote of paracetamol poisoning
Gastric lavage is contraindicated in the following:
A patient presented to the emergency department with an overdose of a drug, exhibiting increased salivation and increased bronchial secretions. On examination, the blood pressure was 88/60 mmHg, and the RBC cholinesterase level was reduced to 50% of normal. What should be the treatment for this individual?
All are features of organophosphorus poisoning, except:
Which of the following is the recommended treatment for iron poisoning in a 4-year-old child?
A 12-year-old boy presents with difficulty in reading from the blackboard in school. Initially refraction error was considered but visual acuity was normal. He has started complaining of diplopia on watching TV or after studying for long. He takes very long time to finish his meals and his speech becomes very difficult to understand after speaking continuously for few minutes. Anti-Acetylcholine receptor blocking antibody is detected in high titers. All are done in management except? (Recent NEET Pattern 2016-17)
Which is true about an infant with failure to thrive and the following findings?
What is the capillary refill time in a child with shock?
Poisoning and Toxidromes Indian Medical PG Practice Questions and MCQs
Question 1: A farmer with pinpoint pupils, increased secretions and urination. What is the most likely diagnosis?
- A. Alcohol poisoning
- B. Organophosphate poisoning (Correct Answer)
- C. Opioid poisoning
- D. Atropine poisoning
Explanation: ***Organophosphate poisoning*** - **Pinpoint pupils (miosis)**, **increased secretions** (salivation, lacrimation, bronchial secretions), and **urination** are classic signs of cholinergic crisis caused by organophosphate toxicity [1]. - The patient's profession as a **farmer** increases the likelihood of exposure to pesticides, which often contain organophosphates [1], [2]. *Alcohol poisoning* - While alcohol poisoning can cause CNS depression, it does not typically present with **pinpoint pupils** or **increased secretions** like salivation and urination. - Common signs include **ataxia**, **slurred speech**, **nausea**, and **vomiting**. *Opioid poisoning* - Opioid poisoning also causes **pinpoint pupils** and **CNS depression**, but it typically leads to **decreased secretions** and **urinary retention**, not increased urination [2]. - **Respiratory depression** is a hallmark feature, which is not highlighted here as a primary symptom. *Atropine poisoning* - Atropine is an anticholinergic agent, meaning it would cause the opposite effects of organophosphate poisoning [2]. - Symptoms would include **dilated pupils (mydriasis)**, **dry mouth**, **decreased secretions**, and **urinary retention**.
Question 2: What is the antidote for acetaminophen overdose?
- A. N-acetylcysteine (NAC) (Correct Answer)
- B. Heparin
- C. Morphine
- D. Benzodiazepine
Explanation: ***N-acetylcysteine (NAC)*** - **N-acetylcysteine (NAC)** is the specific antidote for acetaminophen overdose, working by replenishing **glutathione** stores in the liver. - Glutathione is crucial for detoxifying the toxic metabolite of acetaminophen, **N-acetyl-p-benzoquinone imine (NAPQI)**, thus preventing **hepatic damage**. *Heparin* - **Heparin** is an **anticoagulant** used to prevent and treat various thrombotic events by inhibiting coagulation. - It has no role in the treatment or detoxification of acetaminophen overdose. *Morphine* - **Morphine** is an **opioid analgesic** primarily used for pain management, acting on opioid receptors in the central nervous system. - It is not an antidote for any specific overdose and would exacerbate respiratory depression if given in an opioid overdose. *Benzodiazepine* - **Benzodiazepines** are a class of drugs with **sedative, anxiolytic, muscle relaxant, and anticonvulsant** properties, commonly used for anxiety, insomnia, or seizures. - They are not an antidote for acetaminophen overdose and would not counteract its hepatotoxic effects.
Question 3: The antidote of paracetamol poisoning
- A. Sodium bicarbonate
- B. Flumazenil
- C. N-acetyl cysteine (Correct Answer)
- D. Naloxone
Explanation: ***N-acetyl cysteine*** - **N-acetyl cysteine (NAC)** is the specific antidote for **paracetamol (acetaminophen)** overdose. - NAC works by replenishing **glutathione stores** in the liver, which are crucial for detoxifying the toxic metabolite **N-acetyl-p-benzoquinone imine (NAPQI)**. *Sodium bicarbonate* - **Sodium bicarbonate** is used to treat **metabolic acidosis** and certain drug overdoses that cause cardiac toxicity, such as tricyclic antidepressants. - It does not have a direct role in detoxifying paracetamol or its metabolites. *Flumazenil* - **Flumazenil** is an antagonist at the **benzodiazepine receptor** and is used to reverse the sedative effects of benzodiazepine overdose. - It has no effect on paracetamol toxicity. *Naloxone* - **Naloxone** is an **opioid receptor antagonist** used to reverse the effects of opioid overdose. - It does not interact with the metabolic pathways or toxic effects of paracetamol.
Question 4: Gastric lavage is contraindicated in the following:
- A. Barbiturate poisoning
- B. Paracetamol poisoning
- C. Kerosene poisoning (Correct Answer)
- D. Carbolic acid poisoning
Explanation: ***Kerosene poisoning*** - Gastric lavage is contraindicated in **hydrocarbon poisoning** like kerosene due to the high risk of **aspiration pneumonitis**. [1] - Aspiration of hydrocarbons can lead to severe **chemical pneumonitis**, acute respiratory distress syndrome (ARDS), and even death. *Barbiturate poisoning* - Gastric lavage can be useful in **barbiturate poisoning**, especially if presenting within 1-2 hours of ingestion, to remove unabsorbed drug. - It's part of the management strategy to reduce drug absorption and potentially speed up recovery. *Paracetamol poisoning* - **Gastric lavage** may be considered in paracetamol overdose, particularly if performed within 1-2 hours of ingestion, to remove unabsorbed drug. - However, **activated charcoal** is usually the preferred method for gastric decontamination in paracetamol overdose, followed by **N-acetylcysteine**. *Carbolic acid poisoning* - While typically considered a corrosive, gastric lavage might be cautiously used in **carbolic acid (phenol) poisoning** in specific circumstances, such as very early presentation or large ingestions, but it carries risks of esophageal injury. [2] - Dilution with milk or water is often preferred, but lavage should be avoided if there's evidence of significant caustic injury or perforation risk.
Question 5: A patient presented to the emergency department with an overdose of a drug, exhibiting increased salivation and increased bronchial secretions. On examination, the blood pressure was 88/60 mmHg, and the RBC cholinesterase level was reduced to 50% of normal. What should be the treatment for this individual?
- A. Atropine (Correct Answer)
- B. Physostigmine
- C. Flumazenil
- D. Neostigmine
Explanation: ***Atropine*** - The patient exhibits symptoms of **cholinergic crisis** (increased salivation, bronchial secretions, hypotension) and reduced RBC esterase, strongly indicative of **organophosphate poisoning**. - **Atropine** is the primary antidote, as it competitively blocks muscarinic acetylcholine receptors, reversing the parasympathetic effects. *Neostigmine* - **Neostigmine** is an **acetylcholinesterase inhibitor**, meaning it would worsen the cholinergic crisis by increasing acetylcholine levels further. - It is used in conditions like **myasthenia gravis** to improve muscle strength, not in organophosphate poisoning. *Flumazenil* - **Flumazenil** is an **antagonist of benzodiazepine receptors** and is used to reverse benzodiazepine overdose. - It has no role in treating organophosphate poisoning or cholinergic symptoms. *Physostigmine* - **Physostigmine** is also an **acetylcholinesterase inhibitor** that can cross the blood-brain barrier. - While it has some ophthalmic uses, it would exacerbate the cholinergic symptoms of organophosphate poisoning due to increased acetylcholine.
Question 6: All are features of organophosphorus poisoning, except:
- A. Lacrimation
- B. Bradycardia
- C. Sweating
- D. Mydriasis (Correct Answer)
Explanation: ***Mydriasis*** - Organophosphorus poisoning leads to excessive **acetylcholine** activity, causing **miosis** (pinpoint pupils), not mydriasis. - Mydriasis would indicate **anticholinergic** effects, which are opposite to the symptoms of organophosphorus poisoning. *Lacrimation* - Excess **acetylcholine** stimulates **muscarinic receptors** in lacrimal glands, leading to excessive tear production. - This is a classic "SLUDGE" symptom (Salivation, Lacrimation, Urination, Defecation, Gastric upset, Emesis). *Bradycardia* - Increased **acetylcholine** activity at cardiac muscarinic receptors (M2 receptors) slows the heart rate, causing **bradycardia**. - This is a common and potentially dangerous cardiovascular effect of organophosphorus poisoning. *Sweating* - **Acetylcholine** acts on muscarinic receptors in secretory glands, including sweat glands, causing profuse **sweating**. - This is another characteristic cholinergic symptom due to widespread autonomic overstimulation.
Question 7: Which of the following is the recommended treatment for iron poisoning in a 4-year-old child?
- A. Blood transfusion
- B. Stomach lavage
- C. Observation and supportive care
- D. Deferoxamine IV at a dose of 15 mg/kg/hour (Correct Answer)
Explanation: ***Deferoxamine IV at a dose of 15 mg/kg/hour*** - **Deferoxamine** is a chelating agent specifically used to bind free iron, forming a complex that can be excreted renally. - An intravenous infusion at 15 mg/kg/hour is the recommended dose for severe iron poisoning, particularly when serum iron levels are high or symptoms indicate significant toxicity. *Stomach lavage* - **Stomach lavage** is generally not recommended for iron poisoning due to the risk of pushing iron tablets further into the intestine, potential for perforation, and limited efficacy in removing large, unabsorbed iron tablets. - Iron tablets are often **large** and **poorly soluble**, making lavage ineffective for complete removal. *Blood transfusion* - **Blood transfusion** is not a primary treatment for iron poisoning because iron toxicity is due to free iron in the body, not a deficiency that would be corrected by transfused blood. - It would only be considered in cases of severe anemia or significant blood loss, which are not direct treatments for iron overload. *Observation and supportive care* - While supportive care is crucial in managing complications of iron poisoning, **observation alone is insufficient** for moderate to severe cases of iron poisoning. - Significant iron overdose requires active intervention to prevent systemic toxicity, organ damage, and potentially fatal outcomes.
Question 8: A 12-year-old boy presents with difficulty in reading from the blackboard in school. Initially refraction error was considered but visual acuity was normal. He has started complaining of diplopia on watching TV or after studying for long. He takes very long time to finish his meals and his speech becomes very difficult to understand after speaking continuously for few minutes. Anti-Acetylcholine receptor blocking antibody is detected in high titers. All are done in management except? (Recent NEET Pattern 2016-17)
- A. Pyridostigmine
- B. Atropine (Correct Answer)
- C. Steroids
- D. CT chest
Explanation: ***Atropine*** - The patient's symptoms (diplopia, dysphagia, dysarthria, and improvement with rest, along with high titers of **anti-acetylcholine receptor blocking antibody**) are classic for **myasthenia gravis (MG)** [1], [2]. - **Atropine** is an anticholinergic agent that may occasionally be used to manage muscarinic side effects of cholinesterase inhibitors (like pyridostigmine), such as bradycardia, hypersalivation, or diarrhea [3]. - However, **atropine is NOT a primary treatment modality for MG** and is not part of routine management protocols [3]. It does not address the underlying pathophysiology or improve muscle strength. - In contrast, the other options represent core components of MG management. *Pyridostigmine* - **Pyridostigmine** is an **acetylcholinesterase inhibitor** and is the **first-line symptomatic treatment** for myasthenia gravis [1]. - It increases the amount of acetylcholine available at the neuromuscular junction, improving muscle strength and function. *Steroids* - **Corticosteroids** (like prednisone) are a mainstay of **immunosuppressive therapy** for myasthenia gravis, used to reduce the autoimmune attack on acetylcholine receptors [1]. - They are typically used when symptoms are not adequately controlled by pyridostigmine alone or in moderate to severe cases. *CT chest* - A **CT scan of the chest** is crucial in the initial workup of myasthenia gravis to screen for a **thymoma**, a tumor of the thymus gland. - Thymomas are associated with MG in 10-15% of patients, and their presence often dictates the need for thymectomy. - Even in the absence of thymoma, thymic hyperplasia is common in MG patients.
Question 9: Which is true about an infant with failure to thrive and the following findings?
- A. Hypokalemia
- B. Metabolic alkalosis
- C. Increased urinary sodium (Correct Answer)
- D. Increased cortisol
Explanation: ***Increased urinary sodium*** - This image displays an infant with **ambiguous genitalia**, specifically severe clitoromegaly. This is a classic presentation of **congenital adrenal hyperplasia (CAH)** due to **21-hydroxylase deficiency**. - In salt-wasting CAH, deficient **aldosterone** production leads to **renal sodium loss**, resulting in increased urinary sodium, **hyponatremia**, and **hypotension**, contributing to failure to thrive. *Hypokalemia* - **Hypokalemia** is not typically seen in salt-wasting CAH; rather, **hyperkalemia** is more common due to the lack of aldosterone's mineralocorticoid effect, which normally promotes potassium excretion. - The absence of aldosterone causes sodium to be excreted and potassium to be retained. *Metabolic alkalosis* - **Metabolic alkalosis** is not characteristic of salt-wasting CAH; instead, these infants often develop **metabolic acidosis** due to the loss of sodium bicarbonate and impaired acid excretion. - The primary electrolyte disturbance points towards acidosis, not alkalosis. *Increased cortisol* - In 21-hydroxylase deficiency, the enzyme responsible for converting precursors to **cortisol** and aldosterone is deficient, leading to **decreased cortisol** production. - The adrenal glands instead shunt precursors towards androgen synthesis, causing **adrenal hyperplasia** and the virilization seen in the image.
Question 10: What is the capillary refill time in a child with shock?
- A. Greater than 1 second
- B. Greater than 2 seconds
- C. Greater than 3 seconds (Correct Answer)
- D. Greater than 4 seconds
Explanation: **Explanation:** Capillary Refill Time (CRT) is a rapid clinical assessment tool used to evaluate peripheral perfusion. In a healthy child, CRT is typically less than 2 seconds. In the setting of **shock**, the body initiates a compensatory sympathetic response, leading to peripheral vasoconstriction to divert blood flow to vital organs (heart and brain). This reduced cutaneous perfusion results in a delayed CRT. * **Why Option C is Correct:** According to the **PALS (Pediatric Advanced Life Support)** and **WHO** guidelines, a CRT of **greater than 3 seconds** is considered a clinical sign of impaired systemic perfusion and is a hallmark of shock in children. It indicates significant peripheral vasoconstriction or decreased cardiac output. * **Why Options A & B are Incorrect:** A CRT of 1 or 2 seconds is considered within the **normal physiological range** for a child in a neutral thermal environment. These values do not indicate the circulatory compromise required to diagnose shock. * **Why Option D is Incorrect:** While a CRT >4 seconds certainly indicates shock, it is a late or more severe finding. The standard diagnostic threshold for identifying the onset of clinical shock is >3 seconds. **High-Yield Clinical Pearls for NEET-PG:** * **Technique:** CRT should be measured by applying firm pressure for 5 seconds to a blanchable skin surface (ideally the fingernail bed or chest) at the level of the heart. * **False Positives:** Cold ambient temperature can prolong CRT even in the absence of shock. * **Septic Shock Paradox:** In "Warm Shock" (early distributive shock), the CRT may actually be **brisk (<1 second)** due to peripheral vasodilation, though "Cold Shock" with delayed CRT is more common in pediatrics. * **Dehydration:** A CRT >3 seconds is also a key predictor of >5% dehydration in children with gastroenteritis.
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