General Tox

Question 1

In what scenario does the plant Oleander cause poisoning?

Answer 1

If the plant is burnt the smoke is a toxin, a naturally occurring cardiac glycoside (digoxin)

Question 2

Where do Australian snakes rank in venomousness

Answer 2

The most venomous in the world

Question 3

Why is triaging of tox patients often difficult?

Answer 3

RN’s often not adequately educated on finer details of toxicology
If early presentation may appear well (then markedly deteriorate)
Psych patients poor at giving history, lack of privacy confounds this further
Appropriate triage score difficult without full knowledge of the drugs taken

Question 4

What are the toxic dose ranges for paracetamol?

Answer 4

• IR + SRSingle ingestion >200mg/kg or 10gm over 24hr period
• Multiple IR over 48hrs >300mg/kg or 12gm
• Multiple IR over >48hrs >60mg/kg + abdo pain or N/V

Question 5

What dose range of paracetamol requires double NAC dosing?

Answer 5

> 500mg/kg or >30gm

Question 6

How is Paracetamol metabolised

Answer 6

Most is conjugated via glucoronidation or Sulfation and excreted in urine
5-15% is oxidised to form NAPQI, this is then conjugated to glutathione and excreted in urine
Glutathione depletion leads to panadol toxicity

Question 7

Who is most at risk of repeated supratherapeutic pandol ingestion?

Answer 7

All recorded deaths of panadol overdose under 6yrs of age have been from this
15% of adults have toxicity from this

Question 8

What are the features of aspirin (salicylate) toxicity?

Answer 8

6-12hrs to reach peak
CNS: Tinnitus, hearing, vertigo, altered consciousness, seizures, cerebral oedema
GI: N/V, abdo pain
Acid Base: Resp alkalosis, then eventually HAGMA

Question 9

What are the serum disturbances in insulin overdose?

Answer 9

Hypoglycaemia
hypokalaemia
hypomagnesaemia
hypophosphataemia

Question 10

What is the difference between diabetics and non-diabetics with insulin overdose

Answer 10

• Diabetics will have blunted initial symptoms and signs to the overdose, if T2DM may require higher insulin doses to have effect
• Non-diabetics get hyperinsulinaemia when weaning dextrose infusions and may have rebound hyperglycaemia

Question 11

What are the one pill kill meds and what is a good mnemonic?

Answer 11

Opioids
(hydroxy)chlorquines

Beta blockers/Calcium channel blockers
Amphetamines
Sulfonylureas
TCA’s/Theophylline

“OH you little BASTard”

Question 12

What are the features of serotonin toxicity?

Answer 12

Triad of mental state changes, neuromuscular and autonomic excitation

Mental- agitation, seizures
Autonomic- tachycardia, hyperthermia
Neuromuscular- tremor, hyperreflexia, clonus, rigidity

Question 13

What are the features of neuroleptic malignant syndrome?

Answer 13

Tetrad of symptoms, more insidious course over days to weeks

Hyperthermia
Muscular rigidity
Autonomic instability
Altered mental status, particularly mutism and catatonia

Question 14

What differentiates NMS from serotonin syndrome (SS)?

Answer 14

• NMS slower onset (days to weeks, SS faster approx 12hrs
• NMS doesnt have myoclonus, hyperreflexia (normal to hyporeflexic), ataxia or shivering
• Rigidity (hypertonia) and hyperthermia more severe in NMS
• GI upset more common in SS
• SS has bowel hyperactivity but NMS has ileus
• Careful drug history
• SS has mydriasis, NMS doesnt

Question 15

What are the components of the general care for a patient with a toxicological overdose?

Answer 15

R RSI DEAD

Resuscitation
A- control airway
B- 02
C- Fluids/vasopressors
D- Seizure control (not phenytoin) and correct hypoglycaemia
E- electrolytes/temperature

Risk assessment
- Agent(s), dose, time, clinical features, co-morbidities
Supportive care
Investigations
- ECG, paracetamol, VBG
- CK, ?trop ?serum osmolality

Decontamination
- WBI for iron + SR tablets
- Charcoal
Enhanced elimination
- dialysis, haemoperfusion, urinary alkalinisation and plasmapharesis
Antidotes
Disposition

Question 16

What are the components of the risk assessment for an overdose?

Answer 16

Agent(s) and type (ie MR vs IR)
Dose (amount, repeated doses etc)
Time since ingestion
Patient weight/co-morbidities
Events since ingestion (clinical progress, worsening or improving etc)

In children don’t forget NAI, assume all missing agents have been ingested (don’t account for spillage)

Question 17

What are the common naturally occurring cardiac glycosides (ie digoxin analogues)?

Answer 17

Oleander
Foxglove
Lily of the valley
Cane toads

Question 18

What are the potential issues with Lithium use?

Answer 18

Nephrogenic diabetes inspidus
- causing hypernatraemia and AKI
CKD
SILENT syndrome
- Syndrome of lithium effectuated irreversible neurotoxicity
- Can occur with chronic use but at highest risk with rapid treatment of chronic lithium toxicity (? similar to treating chronic hyponatraemia)
- Cerebellar and cognitive dysfunction

Question 19

How should a pressure immobilisation bandage be placed?

Answer 19

• Firm bandage directly over the bite area, wide and elasticised
• Apply second bandage to the entire limb
• Start distal and go proximal
• Use a splint or sling to prevent further limb movement

Question 20

What are the criteria for safe removal of a PIB? what is the post removal managent

Answer 20

Criteria
- 1 hour post bite with no clinical or laboratory evidence of envenomation

Post removal
- Repeat blood tests at 1, 6 and 12hrs
- Continue to monitor patient for 12hrs
- Reapply PIB if evidence of envenomation occurs and contact toxicology/prepare antivenom

Question 21

What are the Hunter criteria for Serotonin syndrome?

Answer 21

Patients must have taken a serotonergic med + have one of the below crtieria

• Spontaneous clonus
• Inducible clonus + agitation or diaphoresis
• Ocular clonus + agitation or diaphoresis
• Tremor + hyperreflexia
• Hypertonia + temp >38C + ocular clonus or inducible clonus

84% sens, 97% spec

Question 22

Who is at greater risk for Paracetamol toxicity?

Answer 22

Hyperactive enzymes
- Alcoholics
- Epileptics on Phenytoin or Carbamezepine
- Rifampicin use
- Phenobarbitol

Depleted Glutathione
- Eating disorders
- Prolonged starvation
- HIV
- Cystic fibrosis

Question 23

What are the criteria for for referral to a liver transplant centre for panadol overdose?

Answer 23

Kings College Criteria predicts poor prognosis from paracetamol induced hepatic failure
Used to determine who needs IMMEDIATE transfer to transplant centre

• pH <7.30

OR all 3 of

• INR >6.5 or PT >100sec
• Cr >300
• Grade III/IV hepatic encephlaopathy

Question 24

What are some other criteria for liver transplant in paracetamol overdose that may not be immediate?

Answer 24

• INR >3.0 at 48hrs or >4.5 at any time
• Ongoing oliguria/Cr >200
• Persistent lactate >3
• Hypotension <80 SBP
• Persistent encephalopathy
• Hypoglycaemia
• Severe thrombocytopaenia
• Phosphate >1.2mmol at >48hrs

Question 25

What are the main drugs that cause prolonged QTc?

Answer 25

Antiarrhthymics
- Sotalol (most common)
- Amiodarone, qunidine, procainamide

Psychotropics
- Haloperidol (most common)
- Chlorpromazine

Antidepressants
- TCA’s, mirtazapine, citalopram

Opioids
- Methadone, loperamide

Antiemetics
- Ondansetron, droperidol, Maxalon

Antimicrobials
- Macrolides (azithromycin)
- Flouroquinolones (cipro)
- Antifungals (fluconazole)

Others
- Tyrozine kinase inhibitors
- Arsenic

Question 26

What are the potential Tox causes of a coma?

Answer 26

• Opiates
• Benzo’s
• Hypoglycaemics
• Antipsychotics (ie Quetiapine)
• TCA’s
• Salicylates
• Alcohols (Ethylene glycol, Ethanol, Methanol)
• Anti-epileptics (Valproate, Carbamezepine)
• Organophosphates

and many more…

Question 27

What toxicological ingestions can cause seizures refractory to benzodiazepines?

Answer 27

• Isoniazid (pyridoxine)
• Phenytoin (dialysis)
• Hypoglycaemics (need glucose)
• Procholinergics (organophosphates)

Question 28

What are some of the indications for liver transplant in paracetamol toxicity?

Answer 28