Corrections - Paracetamol & Alcohol, Overdoses

Question 1

Why is urea raised disproportionately to creatinine in dehydration?

Answer 1

As some urea is reabsorbed with the increased water reabsorption that occurs in dehydration.

Question 2

What scoring system is used to assess alcohol withdrawal severity?

Answer 2

The revised Clinical Institute Withdrawal Assessment for Alcohol (CIWA) scale

Question 3

Presentation of serotonin syndrome?

Answer 3

1) neuromuscular excitation:
- hyperreflexia
- myoclonus
- rigidity

2) autonomic nervous system excitation:
- hyperthermia
- sweating

3) altered mental state: confusion

Question 4

Management of serotonin syndrome?

Answer 4

1) supportive including IV fluids

2) benzodiazepines

3) more severe cases: use serotonin antagonists e.g. cyproheptadine and chlorpromazine

Question 5

What is a transaminitis (elevated ALT and AST) in the 10,000s most commonly caused by?

Answer 5

Paracetamol overdose

Question 6

Pathophysiology in carbon monoxide poisoning?

Answer 6

1) Carbon monoxide binds readily to haemoglobin, forming carboxyhaemoglobin –> reduced oxygen-carrying capacity

2) In carbon monoxide poisoning the oxygen saturation of haemoglobin decreases leading to an early plateau in the oxygen dissociation curve.

Question 7

What may questions regarding carbon monoxide poisoning hint at?

Answer 7

Questions may hint at badly maintained housing e.g. student houses.

Question 8

Features of carbon monoxide poisoning?

Answer 8

1) headache (90%)

2) N&V (50%)

3) vertigo (50%)

4) confusion (30%)

5) subjective weakness (20%)

6) severe toxicity:
- ‘pink’ skin and mucosae
- hyperpyrexia
- arrhythmias
- extrapyramidal features
- coma
- death

Question 9

Why may a pulse ox be falsely high in carbon monoxide poisoning?

Answer 9

Due to similarities between oxyhaemoglobin and carboxyhaemoglobin.

Question 10

1st line investigation in carbon monoxide poisoning?

Answer 10

VBG or ABG

Question 11

Management of carbon monoxide poisoning?

Answer 11

1) 100% high-flow oxygen via a non-rebreather mask: target sats 100%

2) hyperbaric oxygen

Question 12

What is the single most important prognostic factor in paracetamol overdose?

Answer 12

ABG pH (indicative factor of a poor outcome requiring liver transplantation).

Question 13

What is the liver transplantation criteria in paracetamol overdose regarding pH?

Answer 13

pH <7.3 more than 24 hours after ingestion

Question 14

What type of urinary incontinence can TCAs cause?

Answer 14

Overflow

Question 15

What is the King’s criteria for liver transplantation (paracetamol liver failure)?

Answer 15

1) arterial pH <7.3, 24 hours after ingestion

Or all of the following:

2) prothrombin time > 100 seconds

3) creatinine > 300 µmol/l

4) grade III or IV encephalopathy

Question 16

Management options for salicylate OD?

Answer 16

1) urinary alkalinisation with IV bicarbonate

2) haemodialysis if indications e.g. pulmonary oedema, metabolic acidosis

Question 17

Management options for benzo OD?

Answer 17

Flumazenil.

Note - The majority of overdoses are managed with supportive care only due to the risk of seizures with flumazenil. It is generally only used with severe or iatrogenic overdoses.

Question 18

Management options for TCA OD

Answer 18

IV bicarbonate: may reduce the risk of seizures and arrhythmias in severe toxicity

Question 19

Which medications are contraindicated in TCA OD?

Answer 19

1) class 1a (e.g. Quinidine) and class Ic antiarrhythmics (e.g. Flecainide): as prolong depolarisation

2) Class III drugs such as amiodarone: as prolongs QT interval

Question 20

Is dialysis effective in TCA OD?

Answer 20

No

Question 21

Management of lithium OD?

Answer 21

1) Mild-mod: may respond to volume resuscitation with normal saline

2) Severe: haemodialysis

Question 22

Reversal agent for heparin?

Answer 22

Protamine sulphate

Question 23

Reversal agent of iron?

Answer 23

Desferrioxamine, a chelating agent

Question 24

Management of lead OD?

Answer 24

Dimercaprol, calcium edetate

Question 25

Management of CO poisoning?

Answer 25

• 100% oxygen
• hyperbaric oxygen

Question 26

Management of cyanide OD?

Answer 26

Hydroxocobalamin

Also combination of amyl nitrite, sodium nitrite, and sodium thiosulfate

Question 27

Management of paracetamol OD if presentation 8-24 hours after ingestion?

Answer 27

If OD >150 mg/kg –> start acetylcysteine even if the plasma-paracetamol concentration is not yet available

Question 28

Management of beta blocker OD?

Answer 28

1) if bradycardic –> atropine

2) in resistant cases –> glucagon

Question 29

Typical ABG results in salicylate overdose?

Answer 29

Initial respiratory alkalosis (due to hyperventilation) followed by metabolic acidosis (due to lactic acid accumulation)

Question 30

Normal QRS duration?

Answer 30

Between 0.08 and 0.10 seconds

Question 31

Normal QT interval?

Answer 31

From 0.4 to 0.44 seconds

Note - women have a longer QT interval than men

Question 32

How can acute hypoperfusion (e.g. low BP secondary to blood loss) affect the liver?

Answer 32

Can cause ischaemic hepatitis.

This is often characterised by marked elevation in aminotransferase liver enzymes (AST and ALT) which peak 1-3 days after the insult.

Will also be rise in LDH.

Question 33

Features of a beta blocker OD?

Answer 33

• hypotension
• bradycardia
• AV block
• HF
• bronchospasm
• hypoglycaemia, hyperkalaemia

Question 34

What type of reaction can N-Acetylcysteine cause?

Answer 34

N-Acetylcysteine commonly causes an anaphylactoid reaction (non-IgE mediated mast cell release)