Toxicology and Overdose Management Practice Questions

Q: A patient on anti-depressants presented to you with hypotension. An ECG was done, which showed wide QRS complexes and right axis deviation. How will you manage this patient?

Intravenous sodium bicarbonate for TCA-induced arrhythmias. Intravenous sodium bicarbonate for TCA-induced arrhythmias - The patient's presentation with **hypotension**, **wide QRS complexes**, and **right axis deviation** in the context of antidepressant use is highly suggestive of **Tricyclic Antidepressant (TCA) toxicity**. [1] - **Sodium bicarbonate** improves cardiac function by increasing plasma sodium and alkalizing the blood, which reduces the binding of TCAs to myocardial fast sodium channels and alleviates cardiotoxicity. [1] *Use of antiarrhythmics* - Many antiarrhythmics, particularly **Class IA and IC agents**, block sodium channels and could exacerbate TCA-induced cardiotoxicity. [1] - Furthermore, antiarrhythmics may worsen hypotension and prolong the QRS interval in TCA overdose. *Administration of propranolol* - **Propranolol** is a non-selective beta-blocker that can worsen **hypotension** and **bradycardia**, which are common in TCA overdose. - It would not address the primary issue of **sodium channel blockade** caused by TCAs. *Use of phenytoin* - **Phenytoin** acts by blocking sodium channels and is used for certain arrhythmias, but its efficacy in TCA toxicity is limited and can be proarrhythmic. - **Sodium bicarbonate** is the preferred treatment as it is more effective at reversing the cardiotoxic effects of TCAs. [1]

Q: What is the immediate emergency treatment for carbon monoxide (CO) poisoning?

High flow O2. ***High flow O2*** - **High-flow oxygen** is the immediate emergency treatment for CO poisoning because it helps to displace CO from **hemoglobin**, thereby increasing oxygen delivery to tissues [1], [2]. - CO has a much **higher affinity** for hemoglobin than oxygen, so administering high concentrations of oxygen helps to reverse this binding and accelerate CO elimination [2]. *5% CO2 inhalation* - Administering **CO2** would worsen the patient's condition as it can cause **respiratory acidosis** and increase cerebral blood flow, potentially exacerbating CO toxicity. - CO2 inhalation would not effectively displace **carbon monoxide** from hemoglobin. *10% CO2 inhalation* - Similar to 5% CO2, **10% CO2 inhalation** would be detrimental, leading to significant **acidosis** and further compromising respiratory function. - This treatment does not address the primary issue of **carbon monoxide** binding to **hemoglobin** [2]. *Nitroglycerine* - **Nitroglycerine** is a vasodilator primarily used for conditions like **angina** or **heart failure**; it has no role in treating CO poisoning. - It would not help in displacing **carbon monoxide** or improving tissue oxygenation.

Q: What is the most appropriate initial management for paralysis resulting from organophosphorus poisoning?

Supportive care, including respiratory support. **Supportive care, including respiratory support** * **Paralysis** in organophosphorus poisoning (OPP) is often due to **nicotinic effects** at the neuromuscular junction, leading to respiratory muscle weakness and failure [2]. * **Respiratory support** through mechanical ventilation is crucial to maintain oxygenation and prevent complications while awaiting the effects of antidotal therapy [1], [2]. * *Atropine to counteract muscarinic symptoms* * **Atropine** primarily blocks **muscarinic receptors**, effectively treating symptoms like bradycardia, bronchorrhea, and miosis [2]. * It does **not reverse the nicotinic effects** responsible for muscle paralysis and respiratory failure. * *Oximes to reactivate acetylcholinesterase* * **Oximes (e.g., pralidoxime)** reactivate **acetylcholinesterase**, thereby addressing the underlying cause of acetylcholine accumulation [2]. * They are most effective if given **early** before irreversible aging of the enzyme occurs, but their effect on established paralysis can be limited without concurrent respiratory support [2]. * *No specific antidote* * This statement is incorrect; **atropine** and **oximes** are specific antidotes for organophosphorus poisoning [2]. * While these antidotes are vital, initial management prioritizing **airway and breathing support** is paramount due to the life-threatening respiratory paralysis [1].

Q: A 25-year-old woman presents with recurrent abdominal pain and anaemia. Peripheral blood smear shows basophilic stippling of the red blood cells. What is the most likely diagnosis?

Lead poisoning. ***Lead poisoning*** - The presence of **basophilic stippling** in red blood cells is a hallmark finding of lead poisoning, indicating abnormal hemoglobin synthesis [1]. - Symptoms such as **abdominal pain** and **anaemia** are common presentations due to lead's interference with heme synthesis and gastrointestinal function [1, 2]. *Hookworm disease* - Typically causes **iron deficiency anaemia** due to chronic blood loss, but does not result in basophilic stippling. - Clinical features include **abdominal pain** and **weight loss**, without specific RBC morphology changes seen in lead poisoning. *Coeliac disease* - Characterized by **malabsorption**, which can lead to **anaemia**, but is not associated with basophilic stippling of red blood cells. - Common symptoms include **diarrhea**, **bloating**, and nutritional deficiencies, rather than the specific hematological findings seen in lead poisoning. *Sickle cell disease* - Involves **sickling of red blood cells** and vaso-occlusive crises, but does not present with basophilic stippling or typical anaemia seen in lead poisoning. - Clinical manifestations include **pain episodes** and potential for **acute chest syndrome**, not recurrent abdominal pain as a primary feature.

Q: All are true regarding methanol poisoning except.

Hemodialysis is not required in methanol poisoning.. ***Hemodialysis is not required in methanol poisoning.*** - This statement is **false**, as hemodialysis is often a critical intervention in severe methanol poisoning to actively remove methanol and its toxic metabolites from the body, especially in cases of severe acidosis or organ damage [1]. - Due to the **small molecular size** of methanol and formic acid, **hemodialysis** is highly effective and recommended for rapid clearance. *High anion gap metabolic acidosis is seen in severe cases* - This statement is **true**; methanol is metabolized into **formic acid**, which accumulates and causes a characteristic **high anion gap metabolic acidosis** [2], [3]. - The acidosis is directly responsible for many of the severe clinical manifestations and is a key diagnostic feature [4]. *Visual disturbances are commonly seen* - This statement is **true**; methanol poisoning frequently leads to **visual disturbances**, including blurred vision, photophobia, and even **permanent blindness**, due to the toxic effect of formic acid on the **optic nerve** [2], [4]. - Funduscopic examination may reveal **optic disc hyperemia** or edema in severe cases [4]. *Fomepizole acts by inhibiting alcohol dehydrogenase* - This statement is **true**; **fomepizole** is the antidote for methanol poisoning and works by competing with methanol for the enzyme **alcohol dehydrogenase** [2], [3]. - By inhibiting alcohol dehydrogenase, fomepizole prevents the metabolism of methanol into its toxic metabolites, **formaldehyde** and **formic acid**, thus reducing toxicity [3].

Q: Papilledema is caused by:

Vitamin A intoxication. ***Vitamin A intoxication*** - **Chronic vitamin A intoxication** can lead to **idiopathic intracranial hypertension (pseudotumor cerebri)**, which manifests as papilledema [3]. - The excess vitamin A increases **cerebrospinal fluid (CSF) production** or reduces its absorption, leading to elevated intracranial pressure [1], [2], [3]. *Vitamin D intoxication* - **Vitamin D intoxication** primarily causes **hypercalcemia**, leading to symptoms like nausea, vomiting, polyuria, and renal calculi. - It does not typically cause **increased intracranial pressure** or papilledema. *Vitamin E intoxication* - **Vitamin E intoxication** can interfere with **vitamin K absorption**, increasing the risk of bleeding. - It is not associated with **elevated intracranial pressure** or papilledema [1]. *Vitamin B intoxication* - While some **B vitamins** can have adverse effects in very high doses (e.g., **pyridoxine** can cause neuropathy), they are not known to cause **papilledema** or increased intracranial pressure. - **Vitamin B intoxication** typically has different neurological or systemic manifestations.

Q: Which metal is primarily associated with the formation of 'Saturnine gout'?

Lead. ***Lead*** - **Lead poisoning** is directly associated with **Saturnine gout** (also known as chronic lead nephropathy with gout). - Lead interferes with **renal excretion of uric acid**, leading to its accumulation and subsequent gout attacks [1], [3]. *Cadmium* - **Cadmium exposure** is primarily linked to **renal dysfunction** and **osteomalacia** (Itai-Itai disease), not gout. - While it can affect kidney function, its direct association with hyperuricemia and gout is not as prominent as lead. *Beryllium* - **Beryllium exposure** is known to cause **chronic beryllium disease**, a granulomatous lung disease similar to sarcoidosis. - It does not have a recognized association with the development of gout or hyperuricemia. *Mercury* - **Mercury poisoning** primarily affects the **nervous system** and kidneys, leading to neurological symptoms and nephrotoxicity. - It is not directly associated with the pathogenesis of gout or increased uric acid levels [2].

Question 1

A patient on anti-depressants presented to you with hypotension. An ECG was done, which    showed wide QRS complexes and right axis deviation. How will you manage this patient?

Accepted Answer

Intravenous sodium bicarbonate for TCA-induced arrhythmias

Answer

Use of antiarrhythmics

Answer

Administration of propranolol

Answer

Use of phenytoin

Question 2

What is the immediate emergency treatment for carbon monoxide (CO) poisoning?

Accepted Answer

High flow O2

Answer

5% CO2 inhalation

Answer

10% CO2 inhalation

Answer

Nitroglycerine

Question 3

What is the most appropriate initial management for paralysis resulting from organophosphorus poisoning?

Accepted Answer

Supportive care, including respiratory support

Answer

Atropine to counteract muscarinic symptoms

Answer

Oximes to reactivate acetylcholinesterase

Answer

No specific antidote

Question 4

A 25-year-old woman presents with recurrent abdominal pain and anaemia. Peripheral blood smear shows basophilic stippling of the red blood cells. What is the most likely diagnosis?

Accepted Answer

Lead poisoning

Answer

Coeliac disease

Answer

Hookworm disease

Answer

Sickle cell disease

Question 5

All are true regarding methanol poisoning except.

Accepted Answer

Hemodialysis is not required in methanol poisoning.

Answer

High anion gap metabolic acidosis is seen in severe cases

Answer

Visual disturbances are commonly seen

Answer

Fomepizole acts by inhibiting alcohol dehydrogenase

Question 6

Papilledema is caused by:

Accepted Answer

Vitamin A intoxication

Answer

Vitamin E intoxication

Answer

Vitamin B intoxication

Answer

Vitamin D intoxication

Question 7

Which metal is primarily associated with the formation of 'Saturnine gout'?

Accepted Answer

Lead

Answer

Cadmium

Answer

Beryllium

Answer

Mercury

Toxicology and Overdose Management — MCQs

Toxicology and Overdose Management — MCQs

On this page

Practice by Chapter

Want unlimited practice?