Toxicology - CVS

Question 1

Management of severe calcium channel blocker overdose

Answer 1

IV fluid loading
Calcium gluconate 10%, 60 mls over 5-10 min, x3 Q20 min
Adrenaline infusion 1 mcg/kg/min (up to 60/70)
High dose Insulin Euglycaemic therapy (cardgiogenic shock)
Noradrenaline
Methylene blue (vasoplegic shock)
ECMO

Question 2

How to administer high dose insulin euglycaemic therapy

Answer 2

50 mls of 50% glucose 
1 unit / kg IV rapid acting insulin 
then 
infusion via CVC of 
25g / hr glucose 
0.5 units/kg/hr IV insulin, up to 1-2 u/kg/hr
Replace potassium

Question 3

Indications for digoxin fab fragments

Answer 3

Hyperkalaemia > 5 / 5.5
Ingestion of > 10g / 4g in child
Haemodynamically unstable / arrest
Serum digoxin concentration > 15 nmol/L

Question 4

Dosing of digoxin fab fragments

Answer 4

1 ampoule = 40 mg
40-80 mg reasonable and reassess 
calc: dose (mg) x 0.8 x 2 
unstable - 10 ampoules 
arrest - 20 ampoules

Question 5

Benzodiazepine for sedation in setting of delirium

Answer 5

5mg IV diazepam every 5-10 min

Question 6

Management of toxicological seizures

Answer 6

A/B/C
Check BSL
IV diazepam 5-10 min over 3-5 min

2nd line barbiturate (phenobarbitone 100-300 mg/kg slow IV (10-20 mg/kg)
3rd: pyridoxine if due to isoniazid or hydrazine 70mg/kg to 5g

Question 7

Temperature threshold for intubation and active cooling in toxicological hyperthermia

Answer 7

39.5 deg

Question 8

Name the receptors and side effect involved for various features of antipsychotic overdose

Answer 8

• Dopamine antagonist - muscle rigidity, bradykinsia, temperature regulation
• Muscarinic - delirium, tachycardia, urinary retention
• Histamine - sedation, hypotension
• Alpha adrenergic antagonist - vasodilation / hypotension
• Sodium channel blockade - wide QRS

Question 9

Features of NMS

Answer 9

Altered mental status
Hyperthermia
Autonomic dysfunction
Muscle rigidity

Question 10

Dose of quetiapine with significant symptoms expected and treatment

Answer 10

> 3g
Require intubation / ICU admission
IV fluids
Noradrenaline for hypotension (not adrenaline)

Question 11

Discharge criteria for quetiapine overdose

Answer 11

< 3g, discharge at 4 hrs when well with normal ECG (or 8 hrs if XR) and not at night and psychiatric risk assessment completed.

Question 12

SSRI antidepressant and threshold for seizures / long QT, change in management compared to other SSRI

Answer 12

Escitalopram 300mg
Citalopram 600 mg

Administer charcoal up to 4 hrs
Cardiac monitor to 8 hrs (12 if > 500/1000 mg) compared to 6 hrs.

Question 13

Risk assessment in TCA overdose

Answer 13

> 10 mg/kg significant clinical toxicity

> 20/30 mg/kg: coma, hypotension, seizures and arrhythmias.

Question 14

ECG changes and implication in TCA overdose

Answer 14

R wave > 3 mm, R/S ratio > 0.7 in aVR - seizures / arrhythmias
QRS width > 100 msec - seizures
QRS with > 160 msec - ventricular arrhythmias
Long QT - not predictive clinical toxicity

Question 15

Management of TCA overdose

Answer 15

Secure airway (decrease consciousness, < GCS 12)
Hyperventilation
Sodium bicarbonate 8.4 %, 1-2 mEq/kg, to pH 7.5-7.55

Hypotension: IV fluid, noradrenaline
Resistant arrhythmia with pH >7.5, lignocaine 1.5 mg/kg IV

Question 16

Indications for sodium bicarbonate in TCA overdose

Answer 16

Cardiovascular dysfunction

• QRS > 100 msec
• Hypotension unresponsive to fluid
• Any arrhythmia

Question 17

Symptoms and management in acute lithium overdose

Answer 17

Nausea, vomiting, diarrhoea. 
Supportive care 
Correct sodium / water deficit 
Rarely particularly toxic 
Check level 6 hourly

Question 18

Symptoms and mangement in chronic lithium toxicity

Answer 18

Neurological symptoms - tremor, hyperreflexia, agitation, ataxia –> stupor, rigidity, coma.
Worse if dehydration, hyponatraemia or renal failure.
Haemodialysis if level >4 with renal failure, severe symptoms, of [Li] > 5 mEq/L

Question 19

4 phases of paracetamol toxicity

Answer 19

1: asymptomatic, N/V
2: 1-2 days - hepatotoxicity develops, RUQ pain and abnormal ALT/AST and INR
3: 3-4 days - fulminant liver failure, coagulopathy, metabolic acidosis, jaundice, encephalopathy, death.
4: recovery

Question 20

Factors associated with higher risk in paracetamol overdose

Answer 20

Liver enzyme induction agents 
Liver impairment pre-existing
Chronic alcohol ingestion 
Starvation / prolonged fasting 
Slow release preparations 
Massive ingestion (>500mg/kg, >30g, level > 450 mg/L)
Multiple ingestions 
Unknown time of ingestion

Question 21

Treatment of IR paracetamol, presenting < 8 hrs

Answer 21

Paracetamol level, commence NAC based on level. no further bloods unless high risk group.

Question 22

Treatment of IR paracetamol presenting 8-24 hrs

Answer 22

Commence NAC.
Paracetamol level and LFTs.
Cease if paracetamol level < nomogram and normal LFTs, otherwise complete 20 hr course.
LFTs repeated at 18 hrs.
Further 100mg/kg/16 hrs if AST/ALT rising.

Question 23

Treatment of IR paracetamol presenting > 24 hrs

Answer 23

Commence NAC
Prolonged therapy if LFTs rising at 18 hr bloods. Continue at 100 mg/kg/12 hrs until INR / LFTs normalising or transplant.

Question 24

Treatment of IR paracetamol with unknown timeframe of ingestion

Answer 24

Commence NAC.

Stop at 20 hrs if LFTs normal and paracetamol negative.

Question 25

Treatment of staggered acute overdose

Answer 25

Assume total dose taken at earliest time.
Paracetamol level, commence NAC prior to level if > 8 hrs.
NAC treatment based on assumption of whole dose at earliest time.

Question 26

Supratherapeutic ingestions warranting treatment

Answer 26

> 10 g or 200mg/kg over 24 hrs
6 g or 150 mg/kg over 48 hrs
4 g or 100 mg/kg with risk factors (liver impairment)

Question 27

Management of slow release paracetamol overdose

Answer 27

Commence NAC if > 200 mg/kg
Paracetamol level at 4/presentation + 4 hrs.
If both below level & decreasing, stop.
If increasing / above nomogram - continue for 20 hrs.
Recheck LFTs and paracetamol at 18 hrs.

Question 28

Management of massive paracetamol ingestion

Answer 28

> 500mg/kg, > 30g, level > 450 mg/L
200 mg/kg NAC over 4 hrs
200 mg/kg NAC over 16 hrs (increase from 100mg/kg)

Question 29

Factors associated with poor prognosis / referral to liver treatment unit

Answer 29

INR > 3 at 48 hrs or > 4/4.5 at any stage
pH < 7.3 after resuscitation 
Hypoglycaemia 
Encephalopathy 
Severe thrombocytopaenia 
Cr > 200 
SBP < 80 
Rising serum lactate

Question 30

Management of salicylate toxicity

Answer 30

Alkalinise urine (if symptomatic), target pH > 7.5
Loading dose of sodium bicarb 0.5-1 mEq/kg IV, then infusion of 100-250 mEq/kg/hr
Replace potassium
Maintain urine output 1-2 mls/kg/hr

Haemodialysis if indicated (worsening, renal failure, end organ failure, level > 6 mmol/L)

If intubation - the give Sodium bicarb loading and hyperventilate.

Question 31

Management of sulphonylurea overdose

Answer 31

Correct hypoglycaemia
- 50 mis of 50% glucose or 5 mls/kg of 10 % glucose, then infusion
Suppress endogenous insulin release
- octreotide 50 micrograms IV (1mcg/kg), then 25 mcg/hr (1mcg/kg/hr)

Question 32

Indications for dialysis in metformin overdose

Answer 32

Lactate > 10
Worsening acidosis
Worsening renal failure
Clinical deterioration

Question 33

Risk assessment in colchicine overdose

Answer 33

<500 mcg/kg: GI symptoms
500-800 mcg/kg: BM suppression, 10% mortality
> 800 mcg/kg: CVS collapse, 100% mortality

Question 34

Describe the 3 stages of colchicine overdose

Answer 34

1: GIT - N/V/D/Abdo pain, dehydration and hypotension
2: 24-72 hrs - multi organ failure (Resp - ARDS, CVS - failure/arrhythmia/arrest, Haem - DIC, fever, ileum, renal failure)
3: 6-8 days - recovery, leucocytosis, alopecia

Question 35

GIT symptoms rapidly progressing to multi organ failure

Answer 35

Think of colchicine!