Toxicology Quiz: Central Nervous System Poisons
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Questions and Answers

Which classification of poisons refers to those that affect the Central Nervous System?

  • Corrosive poisons
  • Remote action poisons
  • CNS poisons (correct)
  • GIT poisons

Which factor does NOT modify the toxic effects of a poison?

  • State of the toxic agent
  • Route of administration
  • Dose
  • Patient's age (correct)

What term describes the situation where the combined effect of two chemicals is greater than their individual effects?

  • Antagonism
  • Addition
  • Synergism (correct)
  • Cumulation

Which of the following poisons primarily targets the liver?

<p>Paracetamol (C)</p> Signup and view all the answers

In terms of toxicity based on route of administration, which is the least toxic?

<p>Oral (C)</p> Signup and view all the answers

Which of the following statements about toxic substances is true?

<p>All substances can be toxic depending on the dose. (B)</p> Signup and view all the answers

What does 'chemical interaction by antagonism' refer to?

<p>One chemical completely cancels out the effect of another. (B)</p> Signup and view all the answers

Which factor is a pharmacokinetic factor that affects toxicity?

<p>Chemical structure of the poison (C)</p> Signup and view all the answers

Which method is used for the neutralization of alkaline corrosives?

<p>Weak acids (D)</p> Signup and view all the answers

What is a common consequence of using NaHCO3 for treatment?

<p>Gastric perforation (A)</p> Signup and view all the answers

Which of the following is a chemical that serves as an antidote for cyanide poisoning?

<p>Mercurous chloride (D)</p> Signup and view all the answers

What reaction occurs when weak alkalis are used against acidic corrosives?

<p>Exothermic heat reaction (A)</p> Signup and view all the answers

Which compound is used to precipitate lead in treatment protocols?

<p>MgSO4 (B)</p> Signup and view all the answers

What is a primary contraindication for performing gastric lavage?

<p>History of severe cardiac dysrhythmias (C)</p> Signup and view all the answers

What is the purpose of the cuffed endotracheal tube during gastric lavage?

<p>To prevent aspiration pneumonia (D)</p> Signup and view all the answers

What is the function of activated charcoal in gastrointestinal decontamination?

<p>To adsorb poisons and decrease their absorption (A)</p> Signup and view all the answers

Which statement about the gastric lavage tube is accurate?

<p>It should be inserted 50cm from the front of teeth to epigastrium (C)</p> Signup and view all the answers

Which of these substances is poorly adsorbed by activated charcoal?

<p>Cyanide (A)</p> Signup and view all the answers

Which method can be used to verify proper placement of the gastric tube in the stomach?

<p>Assessing for cough or dyspnea (D)</p> Signup and view all the answers

What should be done if a patient experiences convulsions during the procedure of gastric lavage?

<p>Perform gastric lavage under general anesthesia (D)</p> Signup and view all the answers

What is the recommended dosage range of activated charcoal for adults?

<p>50gm - 100gm (C)</p> Signup and view all the answers

What is the primary purpose of gastrointestinal decontamination in cases of poisoning?

<p>To remove the poison from the gastrointestinal tract and prevent absorption. (B)</p> Signup and view all the answers

Which of the following is NOT a method of gastrointestinal decontamination?

<p>Intravenous fluid therapy. (D)</p> Signup and view all the answers

Which condition is a contraindication for emesis in poisoning cases?

<p>Infants under six months of age. (A)</p> Signup and view all the answers

In which scenario is gastric lavage considered for use beyond the typical 3-hour window?

<p>Ingestion of barbiturates that slow gastric motility. (D)</p> Signup and view all the answers

What is the primary focus of supportive therapy during the treatment of poisoning?

<p>Treat the patient, not the poison (A)</p> Signup and view all the answers

What is a common risk associated with the emesis method of gastrointestinal decontamination?

<p>Inhalation of vomit leading to aspiration pneumonia. (C)</p> Signup and view all the answers

Which coma scale is preferred for definitive monitoring of toxic coma?

<p>Reed’s coma scale (A)</p> Signup and view all the answers

What is the role of activated charcoal in the treatment of poisoning?

<p>It adsorbs the poison and prevents its absorption in the gastrointestinal tract. (A)</p> Signup and view all the answers

In the context of airway management during poisoning treatment, which intervention is NOT recommended?

<p>Remove any organic food from the patient's stomach (B)</p> Signup and view all the answers

Which of the following statements is true regarding the use of emesis?

<p>Emesis may lead to new convulsive episodes in patients with a history of seizures. (C)</p> Signup and view all the answers

Which substance should be administered to all comatose patients unless hypoglycemia has been excluded?

<p>Dextrose (D)</p> Signup and view all the answers

What action is crucial when managing breathing difficulties in a patient with poisoning?

<p>Use of nasal cannula or simple face mask (C)</p> Signup and view all the answers

Which type of poison is considered safe to manage with emesis?

<p>Minimal toxicity substances. (B)</p> Signup and view all the answers

Which drug is used to treat altered mental status in poisoning cases?

<p>Naloxone (A)</p> Signup and view all the answers

How should hypotension be treated in a patient suffering from poisoning?

<p>By administering vasopressors (D)</p> Signup and view all the answers

Which of the following is NOT a component of the AVPU system for assessing consciousness?

<p>Motor skills assessment (A)</p> Signup and view all the answers

Which of the following is a commonly used osmotic cathartic?

<p>Sorbitol (B)</p> Signup and view all the answers

What is the purpose of whole bowel irrigation?

<p>To cleanse the bowel of poison rapidly (A)</p> Signup and view all the answers

Forced diuresis primarily aims to achieve which of the following?

<p>Increase glomerular filtration rate (D)</p> Signup and view all the answers

Ion trapping in the context of poison elimination refers to which of the following?

<p>Increased secretion of ionized drugs due to pH alteration (D)</p> Signup and view all the answers

What is the recommended urine output to maintain during forced diuresis?

<p>300-500 ml/hr (C)</p> Signup and view all the answers

Which of the following drugs would be best treated with urine alkalinization during poisoning management?

<p>Salicylates (C)</p> Signup and view all the answers

Plasmapheresis is classified under which method of poison elimination?

<p>Extracorporeal methods (A)</p> Signup and view all the answers

What is a common laxative used in the decontamination of poisoning?

<p>Magnesium citrate (C)</p> Signup and view all the answers

Flashcards

What is Toxicology?

The study of poisons and their effects on living organisms.

What is Dose in Toxicology?

The amount of a substance needed to cause a toxic effect. It's a crucial factor in determining if a substance is harmful or not.

What is Route of Administration?

The process by which a poison enters the body.

What is Cumulation?

When the body builds up a poison faster than it can break it down, leading to toxic levels accumulating over time.

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What is Synergism?

Similar to cumulation, it involves a poison's effects being greatly increased when combined with other substances.

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What is Metabolism of a Toxic Agent?

When a poison is broken down into less harmful substances by the body.

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How does Stomach pH affect Poison Toxicity?

The effects of a poison are intensified by increased stomach acidity.

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What is Pharmacokinetics?

The study of how poisons move through the body; including absorption, distribution, metabolism, and elimination.

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Emesis

Removal of stomach contents by inducing vomiting. Often used for recent poison ingestion within 3 hours.

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Gastric Lavage

Removal of stomach contents by washing with a tube. Used for recent ingestions, especially when emesis fails, or for poisons that stick to the stomach.

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Emetic

A drug that induces vomiting. Peripherally acting drugs target the stomach directly, while centrally acting drugs act on the brain to trigger vomiting.

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Contraindication for Emesis

A condition that causes vomiting. Common examples are CNS issues like coma or convulsions, severe heart problems, stomach issues like varices, and ingestion of certain poisons.

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Corrosive Poison

A type of poison that irritates and damages the lining of the stomach. Examples include strong acids or bases.

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Volatile Hydrocarbon

A flammable liquid poison that can cause lung damage if aspirated into the lungs.

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Activated Charcoal

A substance that absorbs and traps poisons in the stomach, preventing them from being absorbed into the bloodstream.

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Cathartics

Substances that speed up the passage of waste through the digestive system. Helps to reduce the amount of time a poison is in the body.

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AVPU Scale

Measures the level of consciousness using a scale with four levels: Alert, Verbal response, Pain response, and Unresponsive. It's a rapid way to assess someone's awareness.

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Reed's Coma Scale

A coma scale similar to the Glasgow Coma Scale, but it emphasizes the depth of coma instead of just responses. It's useful in toxicology cases.

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Treat the Patient, Not the Poison

The key to managing poisoning is to treat the patient and their symptoms, not just focus on the specific poison.

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Supportive Therapy: ABCs

An essential first step in treating a poisoned patient involves maintaining a clear airway, ensuring adequate breathing, and supporting circulation.

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Coma Cocktail

A combination of drugs used in comatose patients to rule out possible causes or provide immediate treatment. This includes dextrose to address hypoglycemia, thiamine for alcoholics, and naloxone for opioid overdose.

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Gastrointestinal Decontamination

A procedure that aims to remove toxins from the stomach before they can be absorbed into the bloodstream.

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Elimination of Poison from Blood

A method of removing toxins from the body by enhancing their excretion through the kidneys, liver or lungs.

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Antidotes

Substances administered to counteract the effects of a toxin. These are specific to the poison involved.

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Antidote (Chemical)

A treatment method for poisoning that uses chemicals to counter the poison's effects. It involves neutralizing acids or bases, precipitating toxins, reducing or oxidizing poisons, or combining with them to make them less harmful.

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Neutralization of Acidic Corrosives

A method in the treatment of poisoning that involves using a weak alkali to neutralize an acidic corrosive substance. This method is considered obsolete but was previously used before more effective approaches were developed.

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Neutralization of Alkaline Corrosives

A treatment method for poisoning involving using a weak acid to neutralize an alkaline corrosive substance. This method is considered obsolete and is no longer used as a primary treatment.

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Precipitation in Poisoning

A treatment method for poisoning where certain substances are used to convert a soluble and toxic poison into a less soluble, less toxic form. This makes it easier to remove from the body. For example, calcium (Ca) precipitates oxalic acid, while magnesium sulfate (MgSo4) precipitates lead.

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Reduction or Oxidation in Poisoning

The use of chemicals to change the chemical structure of a poison, making it less harmful or easier to eliminate. This involves either reducing or oxidizing the poison.

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Contraindications of gastric lavage

These are the same as contraindications for inducing vomiting, preventing aspiration and managing complications, such as seizures and cardiac arrhythmias.

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What is gastric lavage?

This involves using a long, flexible tube inserted through the mouth or nose into the stomach to remove the poison.

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How to ensure the lavage tube is in the stomach

This involves making sure the tube is in the stomach and not the trachea, checking for symptoms, and observing the tube's behavior.

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What is activated charcoal?

This is a black powder that acts like a sponge, absorbing poisons in the stomach and preventing absorption.

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What poisons does activated charcoal NOT work on?

Activated charcoal is used for many poisons, but it has limitations.

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What is the role of activated charcoal in poisoning?

It's a substance that helps prevent the absorption of poisons in the gastrointestinal tract.

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What is gastrointestinal decontamination?

This is the process of removing poison from poison from the GIT and preventing its absorption into the body.

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What are antidotes?

These are substances that act antagonistically to the poison and counter its effects.

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What is Whole Bowel Irrigation?

A process that aims to remove poison from the gastrointestinal tract (GIT) using non-absorbable isotonic electrolyte solution containing polyethylene glycol.

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How do Cathartics Help in Poisoning Treatment?

The use of drugs that increase bowel movements to help eliminate poison from the digestive system. Examples include magnesium sulfate and sorbitol.

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What is the goal of Forced Diuresis?

Forced diuresis aims to eliminate poison from the blood by boosting the kidneys' filtration rate, thereby increasing urine output.

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How does Altering Urine pH Help in Poisoning Treatment?

This technique involves altering the urine pH by making it either more acidic or alkaline, trapping ionized poison in the urine and preventing its reabsorption.

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What is Hemodialysis and how is it used for poisoning?

A method that speeds up the elimination of poison from the blood through an artificial kidney, usually used in severe cases of poisoning.

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How does Activated Charcoal work in Poisoning Treatment?

A non-absorbable substance that binds to poison in the digestive system, preventing it from being absorbed into the bloodstream.

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What is Haemoperfusion and how is it used in poisoning treatment?

A technique used in poisoning treatment where the blood is purified from the poison by passing it through a filtration system.

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How does Plasmapheresis help in poisoning treatment?

This technique seeks to eliminate poison from the blood by removing a portion of the plasma (liquid part of the blood) and replacing it with fresh plasma.

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Study Notes

General Toxicology

  • Toxicology is the study of poisons on living organisms
  • The term comes from Greek and Latin: toxicum (poison), toxikom (arrow poison), and logia (science or study)
  • Toxicology encompasses the source, kinetics, action, diagnosis (clinical effects, differential diagnosis and lab investigations), prevention and treatment of poisoning.
  • All substances are poisons; only the dose determines the effect.

Classification of Poisons

  • Poisons are classified by nature (solid, liquid, gaseous) and site of action (local, remote, both) and target organ.
    • Corrosives: local and some remote acting
    • Target organs: Gastrointestinal tract (metals, corrosives), Kidneys (mercury, phenol, cadmium), Liver (paracetamol, iron, carbon tetrachloride), Cardiovascular system (digitalis, aconitine), Lungs (metal fumes)
    • Central Nervous System (CNS): stimulants (Amphetamines, cocaine, strychnine) and depressants (hypnotics, narcotics, alcohol, anesthetics)

Factors Modifying Toxic Effects

  • Factors related to the poison:
    • State of the toxic agent
    • Dose
    • Route of administration (descending order of toxicity: inhalation > IV > intraperitoneal > subcutaneous > intramuscular > intradermal > oral > topical)
    • Cumulation (intake rate exceeds elimination rate)
    • Chemical interaction (addition, synergism, antagonism)
    • Metabolism of toxic agents (can lead to equally or more toxic compounds)
  • Factors related to the patient:
    • Gastrointestinal tract (pH of the stomach, amount and type of food)
    • Age
    • State of health
    • Toxicogenetics (Idiosyncrasy - abnormal response to drugs, hereditary basis, e.g. favism and sulphonamide in G6PD patients leading to hemolytic anemia)
    • Hypersensitivity (allergy - exaggerated response to a drug)
    • Tolerance

Diagnosis of Poisoning

  • History (sudden symptoms in a healthy person, symptoms in a group of people consuming the same food, history of recent poison purchase, presence of related materials nearby, history of failure, financial/emotional problems, or suicidal note)
  • Clinical examination (vital signs [BP, pulse, Resp, Temp, neurological examination, pupil's state, chest, abdomen, skin, smell of breath, toxidromes)
  • Laboratory investigations (in both living and dead patients: Qualitative and quantitative analysis of the substance from blood, urine, vomitus, stool, hair, nail and organs; in living patients only: ECG, EEG, electrolytes, arterial blood gases (ABG), liver and kidney function tests)
  • Post-mortem picture (search for stomach smell [phenol, opium, organophosphorus, cyanide], ulcers [corrosives], seeds or tablets, skin smell [eschar colors vary depending on substance, site of injection])
  • Brain: edema or congestion (CO), Respiratory system: signs of asphyxia (barbiturates, opium, CO, HCN)
  • Post-mortem changes: hypostasis, rigor mortis (earlier in convulsants like amphetamines and strychnine), putrefaction (delayed in dehydration like in arsenic poisoning)
  • Coma: causes (toxic [CNS depressants, anticholinergics, toxins causing cellular hypoxia], pathologic [e.g., hepatic failure, renal failure, metabolic], traumatic [head injuries])
  • Coma scales: AVPU system (alert, verbal, pain response, unresponsive) and Reed's coma scale

Treatment of Poisoning

  • Supportive therapy (treat the patient, support ABCs)
    • Airway (keep patent, extended head position, tongue prevention from falling back, remove dentures/foreign bodies, tube use)
    • Breathing (oxygen therapy; simple face mask, nasal cannula, mechanical ventilation)
    • Circulation (hypotension treatment with IV fluids and drugs, vasopressors, inotropics, antiarrhythmics)
    • CNS (altered mental status - coma cocktail, dextrose, thiamine, naloxone)
  • Gastrointestinal decontamination (remove poison and prevent absorption)
    • Emesis (removal by inducing vomiting, indications: recent poison ingestion within 3 hours of ingestion)
    • Gastric lavage (tube for stomach flushing)
    • Activated charcoal (adsorbs poisons)
    • Cathartics (Magnesium sulphate, magnesium citrate, sorbitol)
    • Whole bowel irrigation (non-absorbable isotonic electrolyte solution through nasogastric tube)
  • Elimination of the poison from the blood (enhanced elimination)
    • Forced diuresis and alteration of urine pH
    • Extracorporeal methods (Hemo- and peritoneal dialysis, haemoperfusion, plasmapheresis)
  • Antidotes (local/physiologic chelators - EDTA, BAL, DMSA, DMPS, penicillamine, deferoxamine, physicomechanical - adsorbents, delmulcents, enlanging, dissolvents)

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Description

Test your knowledge on toxic substances and their effects on the human body. This quiz covers various topics including classifications of poisons, the factors affecting toxicity, and methods of treatment for poisoning. Challenge yourself with questions related to Central Nervous System poisons and their mechanisms of action.

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