Lecture 21: Treatment Of Poisoning

Question 1

What are the different treatment strategies for poisoning

Answer 1

• Prevent absorption: Activated charcoal & Whole Bowel Irrigation
• Antidote/ Chelation
• Enhance Elimination: Renal Replacement Therapy
• Support: Deal w/ consequences

Question 2

How does Activated charcoal work?

Answer 2

• Single dose
• High Surface Area due to its porous structure, which provides many binding sites for toxins. This allows it to adsorb (bind to charcoal) drugs, chemicals, and toxins, as they pass through the stomach and intestines and prevents them from being absorbed into the bloodstream through the walls of the intestines.
• instead eliminated from the body when the patient passes stool.

Question 3

What is Whole Bowel Irrigation?

Answer 3

• 1.5/ 2L hr osmotically balanced polyethylene glycol electrolyte solution.
• Induces liquid stool - should pass as clear fluid rectally
• induces fluid flow through the intestines and helps flush out substances that have been ingested, reducing the risk of systemic absorption.

Question 4

When can the enhanced elimination technique be used?

Answer 4

• Low volume of distribution
• High protein binding
• High toxicity
• Drug needs to be in bloodstream

Question 5

What are the main symptoms of aspirin overdose?

Answer 5

• Nausea
• Vomiting
• Flushed
• Hyperventilating
• Resp alkalosis, metabolic acidosis

Question 6

What are some management strategies for aspirin overdose?

Answer 6

• Prevent absorption: AC or WBI
• Support: Fluids and electrolyes
• Enhance elimination: Sodium bicarb (changes pH so more is ionised and isnt reabsorbed)

Question 7

What are some management strategies in opioid overdose?

Answer 7

• Airway adjuncts or definitive supplemental O2 or ventilation
• Naloxone (competes with opioids with receptors. It has a higher affinity but does not produce the same effects. Naloxone reverses the resp depression and sedation caused by opioids.

Question 8

What are some management strategies for Benzodiazepine overdose?

Answer 8

• Airway adjuncts or supplemental O2
• Flumazenil: Can have seizure risk and caution in chronic users

Question 9

What are some signs of paracetamol overdose?

Answer 9

• Right upper abdominal pain (due to liver enlargement or tenderness)
• Jaundice (yellowing of the skin or eyes)
• Elevated liver enzymes (which would be seen on blood tests, e.g., AST, ALT)
• Increased bilirubin (which leads to jaundice)
• Early symptoms: Nausea, Vomiting, Loss of appetite, Sweating, Paleness (pallor)

Question 10

What are the different assessments you do before diagnosing paracetamol overdose?

Answer 10

• Nomogram (using paracetamol conc). Blood draw 4hrs after ingesting
• Liver Function Tests: ALT, AST and bilirubin
• INR, prothrombin, creatinine

Question 11

What should be given in paracetamol overdose?

Answer 11

• N-acetyl cysteine IV using dose in table

Question 12

What are the signs of TCA overdose?

Answer 12

• Anticholinergic: dry mouth, urinary retention, drowsy
• Sodium Channel Block - seizures, QT prolongation
• Alpha Blockers: Hypotension

Question 13

What are some management strategies for TCA overdose?

Answer 13

• Sodium bicarbonate: TCAs block sodium channels in the heart, leading to prolonged QRS intervals and arrhythmias. Sodium bicarbonate works by increasing the pH of the blood, which counteracts this sodium channel blockade and stabilizes the cardiac membranes.
• Benzodiazepines - for seizure control
• Prevent absorption (AC)

Question 14

What are some signs of SSRI overdose?

Answer 14

• Hypotension, drowsy, ataxia (poor muscle control), N and V
• QT prolongation
• Long T1/2
• ECG, observations

Question 15

What are the management strategies for SSRI overdose?

Answer 15

• Prevent absorption: AC
• Magnesium 2g IV 15 mins

Question 16

What are signs of CCB and BB toxicity?

Answer 16

• Hypotension
• Bradycardia
• Heart Block
• Hyperglycaemia (CCB)

Question 17

What are management strategies for BB and CCB toxicity?

Answer 17

• Atropine is the first-line treatment for bradycardia. It works by blocking the effects of vagus nerve stimulation on the heart.
• Glucagon (for BB): It works by increasing intracellular cyclic AMP (cAMP) levels, which counteracts the negative effects of beta-blockade on the heart and improves contractility and heart rate.
• Calcium (Calcium Chloride or Calcium Gluconate): Calcium may help overcome the negative inotropic effects of beta-blockers on the myocardium.
• High-Dose Insulin and Glucose Therapy: is used as an adjunct treatment for severe toxicity or refractory hypotension. Insulin increases myocardial contractility and glucose metabolism, improving cardiac output.

Question 18

What are clinical features or iron poisoning?

Answer 18

• Reduced level of conciousness
• Shock
• Convulsions
• GI haemorrhage

Question 19

What are management strategies for Iron toxicity?

Answer 19

• WBI (AC doesnt bind iron)
• Desferrioxamine IV

Question 20

What are clinical features of lithium toxicity and what are management?

Answer 20

• GI, Neuro, Cardio, Resp (has a narrow therapeutic index)
• Haemodialysis

Question 21

What are some clinical features of stimulant toxicity and some management strategies?

Answer 21

• Agitated, Confused, dilated pupils, hypertension, tachycardia
• ECG, FBC, U&Es, Neuro exam
• Benzodiazepines - HR, BP, Agitation, Chest pain
• Nitrates (avoid BB)