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Therapeutics > Poisoning > Flashcards

Poisoning Flashcards

1
Q

What is a poison?

A

A poison is a substance that causes disturbances to an organism when a sufficient amount is absorbed.

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2
Q

What is a toxin?

A

A toxin is a poison produced biologically.

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3
Q

What is venom?

A

Venom is a toxin that is injected by a bite or sting

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4
Q

What is toxicology?

A

Toxicology is the characterization of potentially adverse effects of foreign chemicals on living organisms.

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5
Q

What is the dose-response relationship in toxicology?

A

The dose-response relationship describes how the magnitude of exposure to a substance relates to the severity of the toxic effect it produces.

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6
Q

Why is understanding the dose-response relationship important in toxicology?

A

Understanding the dose-response relationship is crucial for determining safe exposure levels and assessing the risk posed by chemicals.

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7
Q

How does toxicology contribute to public health protection?

A

Toxicology helps protect public health by identifying harmful substances, determining safe exposure levels, and guiding regulations to prevent adverse health effects from chemical exposures.

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8
Q

What is toxicity?

A

Toxicity is the inherent capacity of a chemical, including drugs, to cause injury.

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9
Q

Routes of exposure of toxicity

A

Skin contact
Inhalation
Ingestion

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10
Q

How can chemicals cause toxicity through skin contact?

A

Chemicals can cause toxicity through skin contact by being absorbed into the body, leading to local or systemic adverse effects.

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11
Q

How can chemicals cause toxicity through inhalation?

A

Chemicals can cause toxicity through inhalation by being breathed into the lungs, where they can enter the bloodstream and affect various organs.

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12
Q

How can chemicals cause toxicity through ingestion?

A

Chemicals can cause toxicity through ingestion by being swallowed and absorbed through the digestive tract, potentially causing harm to internal organs.

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13
Q

Common target tissues for toxic actions of the chemical

A
  • Lungs (vapors or toxic gases)
  • Liver (ingested drugs)
  • Brain
  • Kidneys
  • Heart (ionic gradient disturbances)

The brain and kidney have a high blood flow

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14
Q

What are nonselective actions of chemicals?

A

Nonselective actions are toxic effects that occur regardless of the specific chemical structure or target, often affecting a wide range of cells and tissues.

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15
Q

Give examples of nonselective actions

A
  • Local irritation/ caustic effects
  • Strong alkali or acids
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16
Q

How do chemicals cause local irritation or caustic effects?

A

Chemicals cause local irritation or caustic effects by damaging tissues at the site of exposure or application, leading to inflammation, pain, and tissue damage.

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17
Q

Why is the site of exposure important in chemical toxicity?

A

The site of exposure is important because it determines where the initial damage occurs, influencing the severity and type of injury caused by the chemical.

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18
Q

How do chemicals cause injury by denaturing macromolecules?

A

Chemicals cause injury by denaturing macromolecules (proteins) or cleaving chemical bonds, leading to malfunction and structural damage within cells and tissues.

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19
Q

How do strong alkali or acids cause toxicity?

A

Strong alkali or acids cause toxicity by reacting with and destroying cellular components, resulting in severe burns, tissue necrosis, and systemic toxicity if absorbed.

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20
Q

Give examples of nonselective actions

A
  • Interferes with specific biochemical pathways
  • Chemical has to be absorbed and distributed to a specific pathway
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21
Q

What are selective actions of chemicals?

A

Selective actions of chemicals interfere with specific biochemical pathways, targeting particular enzymes or cellular processes.

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22
Q

How do chemicals exert selective actions in the body?

A

For chemicals to exert selective actions, they must be absorbed into the body and distributed to specific pathways where they can interfere with biochemical processes.

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23
Q

How does Rattex (rodenticide) exert its toxic effects?

A

Rattex contains warfarin, which interferes with the Vitamin K pathway, preventing blood clotting and leading to internal bleeding in rodents.

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24
Q

How does paracetamol cause toxicity?

A

Paracetamol toxicity occurs due to the depletion of glutathione, which is needed to conjugate and detoxify the harmful metabolite NAPQI, leading to liver damage.

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25
Q

What is a key characteristic of chemicals that have selective actions?

A

A key characteristic of chemicals with selective actions is their ability to interfere with specific biochemical pathways, often resulting in targeted but potentially severe toxic effects.

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26
Q

What are immediate toxic actions?

A

Immediate toxic actions are those that lead to symptoms quickly following exposure, often resulting in rapid onset of clinical signs and symptoms.

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27
Q

How does organophosphate poisoning cause immediate symptoms?

A

Organophosphate poisoning inhibits acetylcholinesterase, leading to a buildup of acetylcholine and causing immediate symptoms such as muscle twitching, salivation, and respiratory distress.

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28
Q

What are delayed toxic actions?

A

Delayed toxic actions are those that develop symptoms hours to days after exposure, often complicating diagnosis and treatment.

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29
Q

How is severe iron poisoning characterized by its phases?

A

Severe iron poisoning is characterized by three phases:

  • Early Phase (0.5-2 hours): Symptoms include nausea, vomiting, abdominal pain, and diarrhea.
  • Quiescent Phase (up to 12 hours): Patients may appear stable with no significant symptoms.
  • Life-Threatening Phase: Can include shock, metabolic acidosis, and multi-organ failure.
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30
Q

Management of poisoning

A
  1. Airway
  2. Breathing and oxygenation
  3. Circulation and cardiac monitoring
  4. Diagnosis and Decontamination
  5. Enhancing drug clearance
  6. Frequent re-evaluation and Further symptomatic care
  7. Give antidote
  8. Help
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31
Q

What information should be gathered from the patient and relatives when diagnosing toxicity?

A

Gather information about the toxic substance, time of ingestion, and the amount ingested. Be aware of the potential for inaccurate reporting and mixed ingestion

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32
Q

Why is identifying the toxic substance important in diagnosing toxicity?

A

Identifying the toxic substance is crucial for determining the appropriate treatment and predicting possible symptoms and complications.

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33
Q

How does the time of ingestion affect the diagnosis of toxicity?

A

Knowing the time of ingestion helps assess the progression of symptoms and guides the timing and urgency of interventions.

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34
Q

Why is the amount ingested important in diagnosing toxicity?

A

The amount ingested helps estimate the severity of toxicity and the potential for life-threatening effects, guiding treatment decisions.

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35
Q

What challenges can arise with patient history in toxicity cases?

A

Inaccurate reporting and mixed ingestion can complicate diagnosis, requiring a high index of suspicion and thorough investigation.

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36
Q

What should be assessed during the clinical examination in a suspected toxicity case?

A

Assess for clinical syndromes and specific signs and symptoms that align with the suspected toxic substance, to guide diagnosis and treatment.

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37
Q

Special investigations that can aid your diagnosis

A
  • Arterial blood gas
  • Electrolytes and glucose
  • Liver and kidney function tests
  • FBC and clotting profile
  • Urinalysis
  • ECG
  • Plasma poison concentration eg paracetamol
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38
Q

How is decontamination performed for skin exposure to toxins like organophosphates and hydrofluoric acid?

A

Decontamination for skin exposure involves removing contaminated clothing and thoroughly washing the skin with soap and water to remove the toxin.

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39
Q

What steps are taken to decontaminate eyes exposed to toxins?

A

Eye decontamination involves irrigating the eyes with copious amounts of saline or water to flush out the toxin and reduce damage.

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40
Q

How is decontamination managed for airway exposure to toxic substances?

A

Airway decontamination includes ensuring a patent airway, providing supplemental oxygen, and using bronchodilators or other treatments to manage respiratory distress.

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41
Q

What methods are used for gastric decontamination in toxic ingestion cases?

A

Gastric decontamination methods include induced emesis, gastric lavage, administration of activated charcoal, and whole bowel irrigation, depending on the situation and timing.

42
Q

When is induced emesis or gastric lavage indicated in toxic ingestion cases?

A

Induced emesis or gastric lavage may be considered if the ingestion is recent (typically within 1-2 hours) and the toxin is known to be dangerous, but risks and benefits must be carefully weighed.

43
Q

How does activated charcoal work in gastric decontamination?

A

Activated charcoal adsorbs toxins in the gastrointestinal tract, reducing their absorption into the bloodstream. It is most effective when administered within an hour of ingestion.

44
Q

When is emesis indicated in toxic ingestion cases?

A

Emesis is indicated if the time since ingestion is less than 1 hour, especially in children, and if activated charcoal is not indicated.

45
Q

What are the two methods used to induce emesis?

A

The two methods to induce emesis are stimulation of the pharynx and administration of ipecacuanha syrup.

46
Q

How does pharynx stimulation induce emesis?

A

Pharynx stimulation involves using a finger or an object to stimulate the back of the throat, triggering the gag reflex and inducing vomiting.

47
Q

How is ipecacuanha used to induce emesis?

A

Ipecacuanha syrup is administered orally to induce vomiting by irritating the stomach lining and stimulating the vomiting center in the brain.

48
Q

What are the contraindications for inducing emesis?

A

-Impaired level of consciousness
-Corrosive substances
-Hydrocarbons
-Risk of seizures

49
Q

Why is impaired level of consciousness a contraindication for emesis?

A

Inducing emesis in patients with an impaired level of consciousness increases the risk of aspiration and airway compromise.

50
Q

Why should emesis not be induced for corrosive substances?

A

Inducing emesis after ingestion of corrosive substances can cause further damage to the esophagus and mouth.

51
Q

Why is inducing emesis contraindicated for hydrocarbon ingestion?

A

Hydrocarbons can easily be aspirated into the lungs during vomiting, leading to chemical pneumonitis and other respiratory complications.

52
Q

Why is a risk of seizures a contraindication for emesis?

A

Inducing emesis in patients at risk of seizures can increase the likelihood of aspiration and further complicate the clinical situation.

53
Q

When is gastric lavage useful in toxic ingestion cases?

A

Gastric lavage is useful if the time since ingestion is less than 1-2 hours, particularly for large amounts of toxic solid substances. It is not used routinely or as punishment.

54
Q

What equipment is used for gastric lavage and why?

A

A large-bore catheter (32-40 French) is used for gastric lavage to effectively flush out the stomach contents.

55
Q

What are the recommended volumes of solution for gastric lavage in adults and children?

A

For adults, use 200-300 ml of tap water. For children, use 10 ml/kg of body temperature saline.

56
Q

Why is airway protection important during gastric lavage?

A

Airway protection is crucial to prevent aspiration and ensure that the patient’s airway remains secure during the procedure.

57
Q

What should be monitored during gastric lavage?

A

Monitor for proper decontamination, patient response, and potential complications during and after the procedure.

58
Q

What are the contraindications for gastric lavage?

A
  • Corrosive substances and hydrocarbons
  • Risk of GI haemorrhage
  • Unprotected airway
59
Q

Why should gastric lavage not be performed for corrosive substances?

A

Gastric lavage for corrosive substances can cause further damage to the esophagus and stomach lining.

60
Q

Why is gastric lavage contraindicated for hydrocarbons?

A

Hydrocarbons can cause aspiration into the lungs, leading to chemical pneumonitis, making gastric lavage unsafe.

61
Q

Why should gastric lavage be avoided if there is a risk of gastrointestinal hemorrhage?

A

Gastric lavage can exacerbate gastrointestinal bleeding and cause additional injury to the GI tract.

62
Q

For which substances is activated charcoal useful?

A

Activated charcoal is useful for salicylates, paracetamol, barbiturates, digoxin, and tricyclic antidepressants (TCAs).

63
Q

When should activated charcoal be administered?

A

Activated charcoal should be administered if the time since ingestion is less than 2 hours. It can be used longer if there is delayed gastric emptying.

64
Q

When should multiple doses of activated charcoal (MDAC) be considered?

A
  • Severely poisoned patients
  • Sustained-release tablets
  • Enterohepatic cycling (estrogen, TCAs)
  • Drugs secreted into bile or intestine (digoxin)
65
Q

How does activated charcoal work to reduce toxicity?

A

Activated charcoal works by adsorbing toxins in the gastrointestinal tract, preventing their absorption into the bloodstream.

66
Q

For which substances is activated charcoal not recommended?

A
  • Strong acids or alkalis
  • Iron salts
  • Lithium
  • Petroleum products
  • Cyanide
  • Endoscopy due
  • Antidote by mouth
67
Q

What are the common adverse effects of activated charcoal?

A
  • Vomiting
  • Constipation/diarrhea
  • Intestinal obstruction
68
Q

What are the contraindications for using activated charcoal?

A
  • substances not absorbed by AC
  • Unprotected airway
  • Corrosive ingestion
  • Upper GI perforation
69
Q

How should a patient be monitored after administering activated charcoal?

A

Monitor the patient’s stool for passage of charcoal 6 hours later and ensure adequate hydration to prevent constipation and intestinal obstruction.

70
Q

What is the recommended dose of activated charcoal for adults and children?

A

or adults, the dose is 50-100 grams in a slurry with 500 ml of water. For children, the dose is 10-50 grams in 100-300 ml of water.

71
Q

How can activated charcoal be administered?

A

Activated charcoal can be administered orally or via an NG tube.

72
Q

What should be considered to minimize the risk of intestinal obstruction when using activated charcoal?

A

Ensure adequate hydration to reduce the risk of intestinal obstruction.

73
Q

How should activated charcoal be prepared for children?

A

Mix activated charcoal with water or a soft drink. Consider using bribery with sweets to make the preparation more palatable for children.

74
Q

What is the purpose of whole bowel irrigation?

A

Whole bowel irrigation uses a large volume of PEG electrolyte solution to stimulate peristalsis and clear the gastrointestinal tract of toxins. It is useful for managing lethal doses of iron and body packers.

75
Q

What are the contraindications for whole bowel irrigation?

A
  • Bowel obstruction/perforation
  • Ileus
  • Compromised airway
76
Q

What type of solution is used for whole bowel irrigation?

A

PEG (polyethylene glycol) electrolyte solution is used. It is an osmotically balanced electrolyte solution.

77
Q

How should the patient be positioned during whole bowel irrigation to reduce risk?

A

Position the patient with the head up at a 30° angle to reduce the risk of pulmonary aspiration.

78
Q

How is the effectiveness of whole bowel irrigation determined?

A

The end point of whole bowel irrigation is reached when imaging shows a clear rectal area.

79
Q

How do we enhance drug clearance

A
  • Urinary alkalinisation
  • Haemodialysis
  • Charcoal haemoperfusion
80
Q

How does urinary alkalinization enhance drug clearance?

A

Urinary alkalinization increases the excretion of weak acids by making the urine more alkaline, which helps in trapping the drug in its ionized form and increasing its elimination

81
Q

When is hemodialysis used for enhancing drug clearance?

A

Hemodialysis is used for enhancing drug clearance in cases of severe poisoning or when a drug is dialyzable, especially in acute renal failure or life-threatening overdoses.

82
Q

What is charcoal hemoperfusion and when is it used?

A

Charcoal hemoperfusion involves passing blood through a column containing activated charcoal to adsorb toxins. It is used for drugs that are poorly absorbed by activated charcoal and for severe cases of poisoning.

83
Q

What is the primary purpose of urinary alkalinization?

A

Urinary alkalinization is used to enhance the elimination of weak acids, such as salicylates, by maintaining a urine pH greater than 7.5.

84
Q

How is urinary alkalinization administered?

A

Urinary alkalinization is achieved through the intravenous administration of sodium bicarbonate.

85
Q

What should be monitored during urinary alkalinization?

A

Monitor potassium levels closely, as well as the urine pH to ensure it remains above 7.5.

86
Q

What type of facility is needed for urinary alkalinization?

A

Urinary alkalinization requires a high-care facility due to the need for close monitoring and potential complications.

87
Q

How does hemodialysis work to enhance drug clearance?

A

Hemodialysis uses diffusion of solutes across a semi-permeable membrane to remove toxins from the blood.

88
Q

When is hemodialysis indicated?

A

Hemodialysis is indicated in cases of renal impairment or clinical deterioration despite supportive treatment.

89
Q

Which substances are commonly treated with hemodialysis?

A

Hemodialysis is used for the removal of salicylates, lithium, and methanol.

90
Q

Further symptomatic care

A

Monitor patient and treat:
- Seizures eg cocaine
- Hypoventilation eg opiates
- Hypoglycaemia eg salicylates
- Hypothermia/ hyperthermia
- CVS compromise
- Liver/kidney failure

91
Q

What are the common causes of hypotension in toxicological emergencies?

A

Hypotension can be caused by hypovolemia or vasodilation.

92
Q

What treatments are used for hypotension?

A

Use fluids to address hypovolemia, and vasopressors or inotropes to manage vasodilation.

93
Q

What is often the duration of hypertension in toxicological emergencies?

A

Hypertension is often of short duration.

94
Q

What treatments are used for hypertension?

A

Use benzodiazepines to manage anxiety or agitation, and sodium nitroprusside to rapidly reduce blood pressure.

95
Q

What should be done for bradycardia due to β-blocker overdose?

A

Use atropine or pacing to manage bradycardia

96
Q

What treatments are appropriate for tachycardia caused by stimulants or cocaine?

A

Use benzodiazepines to calm the patient and reduce sympathetic stimulation.

97
Q

How should stable ventricular tachycardia (VT) from TCA overdose be managed?

A

Use sodium bicarbonate or lidocaine to manage stable VT.

98
Q

What is the antidote for digoxin toxicity?

A

Digoxin immune fab.

99
Q

What is the antidote for paracetamol overdose?

A

Acetylcysteine.

100
Q

What is the antidote for opioid overdose?

A

Naloxone.

101
Q

What is the antidote for benzodiazepine overdose?

A

Flumazenil.

102
Q

What is the antidote for iron overdose?

A

Deferoxamine.

Therapeutics (15 decks)

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