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Poisoning Flashcards

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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
What is a key characteristic of chemicals that have selective actions?
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.
26
What are immediate toxic actions?
Immediate toxic actions are those that lead to symptoms quickly following exposure, often resulting in rapid onset of clinical signs and symptoms.
27
How does organophosphate poisoning cause immediate symptoms?
Organophosphate poisoning inhibits acetylcholinesterase, leading to a buildup of acetylcholine and causing immediate symptoms such as muscle twitching, salivation, and respiratory distress.
28
What are delayed toxic actions?
Delayed toxic actions are those that develop symptoms hours to days after exposure, often complicating diagnosis and treatment.
29
How is severe iron poisoning characterized by its phases?
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.
30
Management of poisoning
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
31
What information should be gathered from the patient and relatives when diagnosing toxicity?
Gather information about the toxic substance, time of ingestion, and the amount ingested. Be aware of the potential for inaccurate reporting and mixed ingestion
32
Why is identifying the toxic substance important in diagnosing toxicity?
Identifying the toxic substance is crucial for determining the appropriate treatment and predicting possible symptoms and complications.
33
How does the time of ingestion affect the diagnosis of toxicity?
Knowing the time of ingestion helps assess the progression of symptoms and guides the timing and urgency of interventions.
34
Why is the amount ingested important in diagnosing toxicity?
The amount ingested helps estimate the severity of toxicity and the potential for life-threatening effects, guiding treatment decisions.
35
What challenges can arise with patient history in toxicity cases?
Inaccurate reporting and mixed ingestion can complicate diagnosis, requiring a high index of suspicion and thorough investigation.
36
What should be assessed during the clinical examination in a suspected toxicity case?
Assess for clinical syndromes and specific signs and symptoms that align with the suspected toxic substance, to guide diagnosis and treatment.
37
Special investigations that can aid your diagnosis
- Arterial blood gas - Electrolytes and glucose - Liver and kidney function tests - FBC and clotting profile - Urinalysis - ECG - Plasma poison concentration eg paracetamol
38
How is decontamination performed for skin exposure to toxins like organophosphates and hydrofluoric acid?
Decontamination for skin exposure involves removing contaminated clothing and thoroughly washing the skin with soap and water to remove the toxin.
39
What steps are taken to decontaminate eyes exposed to toxins?
Eye decontamination involves irrigating the eyes with copious amounts of saline or water to flush out the toxin and reduce damage.
40
How is decontamination managed for airway exposure to toxic substances?
Airway decontamination includes ensuring a patent airway, providing supplemental oxygen, and using bronchodilators or other treatments to manage respiratory distress.
41
What methods are used for gastric decontamination in toxic ingestion cases?
Gastric decontamination methods include induced emesis, gastric lavage, administration of activated charcoal, and whole bowel irrigation, depending on the situation and timing.
42
When is induced emesis or gastric lavage indicated in toxic ingestion cases?
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
How does activated charcoal work in gastric decontamination?
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
When is emesis indicated in toxic ingestion cases?
Emesis is indicated if the time since ingestion is less than 1 hour, especially in children, and if activated charcoal is not indicated.
45
What are the two methods used to induce emesis?
The two methods to induce emesis are stimulation of the pharynx and administration of ipecacuanha syrup.
46
How does pharynx stimulation induce emesis?
Pharynx stimulation involves using a finger or an object to stimulate the back of the throat, triggering the gag reflex and inducing vomiting.
47
How is ipecacuanha used to induce emesis?
Ipecacuanha syrup is administered orally to induce vomiting by irritating the stomach lining and stimulating the vomiting center in the brain.
48
What are the contraindications for inducing emesis?
-Impaired level of consciousness -Corrosive substances -Hydrocarbons -Risk of seizures
49
Why is impaired level of consciousness a contraindication for emesis?
Inducing emesis in patients with an impaired level of consciousness increases the risk of aspiration and airway compromise.
50
Why should emesis not be induced for corrosive substances?
Inducing emesis after ingestion of corrosive substances can cause further damage to the esophagus and mouth.
51
Why is inducing emesis contraindicated for hydrocarbon ingestion?
Hydrocarbons can easily be aspirated into the lungs during vomiting, leading to chemical pneumonitis and other respiratory complications.
52
Why is a risk of seizures a contraindication for emesis?
Inducing emesis in patients at risk of seizures can increase the likelihood of aspiration and further complicate the clinical situation.
53
When is gastric lavage useful in toxic ingestion cases?
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
What equipment is used for gastric lavage and why?
A large-bore catheter (32-40 French) is used for gastric lavage to effectively flush out the stomach contents.
55
What are the recommended volumes of solution for gastric lavage in adults and children?
For adults, use 200-300 ml of tap water. For children, use 10 ml/kg of body temperature saline.
56
Why is airway protection important during gastric lavage?
Airway protection is crucial to prevent aspiration and ensure that the patient’s airway remains secure during the procedure.
57
What should be monitored during gastric lavage?
Monitor for proper decontamination, patient response, and potential complications during and after the procedure.
58
What are the contraindications for gastric lavage?
- Corrosive substances and hydrocarbons - Risk of GI haemorrhage - Unprotected airway
59
Why should gastric lavage not be performed for corrosive substances?
Gastric lavage for corrosive substances can cause further damage to the esophagus and stomach lining.
60
Why is gastric lavage contraindicated for hydrocarbons?
Hydrocarbons can cause aspiration into the lungs, leading to chemical pneumonitis, making gastric lavage unsafe.
61
Why should gastric lavage be avoided if there is a risk of gastrointestinal hemorrhage?
Gastric lavage can exacerbate gastrointestinal bleeding and cause additional injury to the GI tract.
62
For which substances is activated charcoal useful?
Activated charcoal is useful for salicylates, paracetamol, barbiturates, digoxin, and tricyclic antidepressants (TCAs).
63
When should activated charcoal be administered?
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
When should multiple doses of activated charcoal (MDAC) be considered?
- Severely poisoned patients - Sustained-release tablets - Enterohepatic cycling (estrogen, TCAs) - Drugs secreted into bile or intestine (digoxin)
65
How does activated charcoal work to reduce toxicity?
Activated charcoal works by adsorbing toxins in the gastrointestinal tract, preventing their absorption into the bloodstream.
66
For which substances is activated charcoal not recommended?
- Strong acids or alkalis - Iron salts - Lithium - Petroleum products - Cyanide - Endoscopy due - Antidote by mouth
67
What are the common adverse effects of activated charcoal?
- Vomiting - Constipation/diarrhea - Intestinal obstruction
68
What are the contraindications for using activated charcoal?
- substances not absorbed by AC - Unprotected airway - Corrosive ingestion - Upper GI perforation
69
How should a patient be monitored after administering activated charcoal?
Monitor the patient's stool for passage of charcoal 6 hours later and ensure adequate hydration to prevent constipation and intestinal obstruction.
70
What is the recommended dose of activated charcoal for adults and children?
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
How can activated charcoal be administered?
Activated charcoal can be administered orally or via an NG tube.
72
What should be considered to minimize the risk of intestinal obstruction when using activated charcoal?
Ensure adequate hydration to reduce the risk of intestinal obstruction.
73
How should activated charcoal be prepared for children?
Mix activated charcoal with water or a soft drink. Consider using bribery with sweets to make the preparation more palatable for children.
74
What is the purpose of whole bowel irrigation?
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
What are the contraindications for whole bowel irrigation?
- Bowel obstruction/perforation - Ileus - Compromised airway
76
What type of solution is used for whole bowel irrigation?
PEG (polyethylene glycol) electrolyte solution is used. It is an osmotically balanced electrolyte solution.
77
How should the patient be positioned during whole bowel irrigation to reduce risk?
Position the patient with the head up at a 30° angle to reduce the risk of pulmonary aspiration.
78
How is the effectiveness of whole bowel irrigation determined?
The end point of whole bowel irrigation is reached when imaging shows a clear rectal area.
79
How do we enhance drug clearance
- Urinary alkalinisation - Haemodialysis - Charcoal haemoperfusion
80
How does urinary alkalinization enhance drug clearance?
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
When is hemodialysis used for enhancing drug clearance?
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
What is charcoal hemoperfusion and when is it used?
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
What is the primary purpose of urinary alkalinization?
Urinary alkalinization is used to enhance the elimination of weak acids, such as salicylates, by maintaining a urine pH greater than 7.5.
84
How is urinary alkalinization administered?
Urinary alkalinization is achieved through the intravenous administration of sodium bicarbonate.
85
What should be monitored during urinary alkalinization?
Monitor potassium levels closely, as well as the urine pH to ensure it remains above 7.5.
86
What type of facility is needed for urinary alkalinization?
Urinary alkalinization requires a high-care facility due to the need for close monitoring and potential complications.
87
How does hemodialysis work to enhance drug clearance?
Hemodialysis uses diffusion of solutes across a semi-permeable membrane to remove toxins from the blood.
88
When is hemodialysis indicated?
Hemodialysis is indicated in cases of renal impairment or clinical deterioration despite supportive treatment.
89
Which substances are commonly treated with hemodialysis?
Hemodialysis is used for the removal of salicylates, lithium, and methanol.
90
Further symptomatic care
Monitor patient and treat: - Seizures eg cocaine - Hypoventilation eg opiates - Hypoglycaemia eg salicylates - Hypothermia/ hyperthermia - CVS compromise - Liver/kidney failure
91
What are the common causes of hypotension in toxicological emergencies?
Hypotension can be caused by hypovolemia or vasodilation.
92
What treatments are used for hypotension?
Use fluids to address hypovolemia, and vasopressors or inotropes to manage vasodilation.
93
What is often the duration of hypertension in toxicological emergencies?
Hypertension is often of short duration.
94
What treatments are used for hypertension?
Use benzodiazepines to manage anxiety or agitation, and sodium nitroprusside to rapidly reduce blood pressure.
95
What should be done for bradycardia due to β-blocker overdose?
Use atropine or pacing to manage bradycardia
96
What treatments are appropriate for tachycardia caused by stimulants or cocaine?
Use benzodiazepines to calm the patient and reduce sympathetic stimulation.
97
How should stable ventricular tachycardia (VT) from TCA overdose be managed?
Use sodium bicarbonate or lidocaine to manage stable VT.
98
What is the antidote for digoxin toxicity?
Digoxin immune fab.
99
What is the antidote for paracetamol overdose?
Acetylcysteine.
100
What is the antidote for opioid overdose?
Naloxone.
101
What is the antidote for benzodiazepine overdose?
Flumazenil.
102
What is the antidote for iron overdose?
Deferoxamine.

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