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?

Paracetamol Signup and view all the answers

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

Oral Signup and view all the answers

Which of the following statements about toxic substances is true?

All substances can be toxic depending on the dose. Signup and view all the answers

What does 'chemical interaction by antagonism' refer to?

One chemical completely cancels out the effect of another. Signup and view all the answers

Which factor is a pharmacokinetic factor that affects toxicity?

Chemical structure of the poison Signup and view all the answers

Which method is used for the neutralization of alkaline corrosives?

Weak acids Signup and view all the answers

What is a common consequence of using NaHCO3 for treatment?

Gastric perforation Signup and view all the answers

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

Mercurous chloride Signup and view all the answers

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

Exothermic heat reaction Signup and view all the answers

Which compound is used to precipitate lead in treatment protocols?

MgSO4 Signup and view all the answers

What is a primary contraindication for performing gastric lavage?

History of severe cardiac dysrhythmias Signup and view all the answers

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

To prevent aspiration pneumonia Signup and view all the answers

What is the function of activated charcoal in gastrointestinal decontamination?

To adsorb poisons and decrease their absorption Signup and view all the answers

Which statement about the gastric lavage tube is accurate?

It should be inserted 50cm from the front of teeth to epigastrium Signup and view all the answers

Which of these substances is poorly adsorbed by activated charcoal?

Cyanide Signup and view all the answers

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

Assessing for cough or dyspnea Signup and view all the answers

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

Perform gastric lavage under general anesthesia Signup and view all the answers

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

50gm - 100gm Signup and view all the answers

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

To remove the poison from the gastrointestinal tract and prevent absorption. Signup and view all the answers

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

Intravenous fluid therapy. Signup and view all the answers

Which condition is a contraindication for emesis in poisoning cases?

Infants under six months of age. Signup and view all the answers

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

Ingestion of barbiturates that slow gastric motility. Signup and view all the answers

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

Treat the patient, not the poison Signup and view all the answers

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

Inhalation of vomit leading to aspiration pneumonia. Signup and view all the answers

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

Reed’s coma scale Signup and view all the answers

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

It adsorbs the poison and prevents its absorption in the gastrointestinal tract. Signup and view all the answers

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

Remove any organic food from the patient's stomach Signup and view all the answers

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

Emesis may lead to new convulsive episodes in patients with a history of seizures. Signup and view all the answers

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

Dextrose Signup and view all the answers

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

Use of nasal cannula or simple face mask Signup and view all the answers

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

Minimal toxicity substances. Signup and view all the answers

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

Naloxone Signup and view all the answers

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

By administering vasopressors Signup and view all the answers

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

Motor skills assessment Signup and view all the answers

Which of the following is a commonly used osmotic cathartic?

Sorbitol Signup and view all the answers

What is the purpose of whole bowel irrigation?

To cleanse the bowel of poison rapidly Signup and view all the answers

Forced diuresis primarily aims to achieve which of the following?

Increase glomerular filtration rate Signup and view all the answers

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

Increased secretion of ionized drugs due to pH alteration Signup and view all the answers

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

300-500 ml/hr Signup and view all the answers

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

Salicylates Signup and view all the answers

Plasmapheresis is classified under which method of poison elimination?

Extracorporeal methods Signup and view all the answers

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

Magnesium citrate Signup and view all the answers

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.