General Tox Flashcards
In what scenario does the plant Oleander cause poisoning?
If the plant is burnt the smoke is a toxin, a naturally occurring cardiac glycoside (digoxin)
Where do Australian snakes rank in venomousness
The most venomous in the world
Why is triaging of tox patients often difficult?
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
What are the toxic dose ranges for paracetamol?
- 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
What dose range of paracetamol requires double NAC dosing?
> 500mg/kg or >30gm
How is Paracetamol metabolised
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
Who is most at risk of repeated supratherapeutic pandol ingestion?
All recorded deaths of panadol overdose under 6yrs of age have been from this
15% of adults have toxicity from this
What are the features of aspirin (salicylate) toxicity?
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
What are the serum disturbances in insulin overdose?
Hypoglycaemia
hypokalaemia
hypomagnesaemia
hypophosphataemia
What is the difference between diabetics and non-diabetics with insulin overdose
- 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
What are the one pill kill meds and what is a good mnemonic?
Opioids
(hydroxy)chlorquines
Beta blockers/Calcium channel blockers
Amphetamines
Sulfonylureas
TCA’s/Theophylline
“OH you little BASTard”
What are the features of serotonin toxicity?
Triad of mental state changes, neuromuscular and autonomic excitation
Mental- agitation, seizures
Autonomic- tachycardia, hyperthermia
Neuromuscular- tremor, hyperreflexia, clonus, rigidity
What are the features of neuroleptic malignant syndrome?
Tetrad of symptoms, more insidious course over days to weeks
Hyperthermia
Muscular rigidity
Autonomic instability
Altered mental status, particularly mutism and catatonia
What differentiates NMS from serotonin syndrome (SS)?
- 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
What are the components of the general care for a patient with a toxicological overdose?
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
What are the components of the risk assessment for an overdose?
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)
What are the common naturally occurring cardiac glycosides (ie digoxin analogues)?
Oleander
Foxglove
Lily of the valley
Cane toads
What are the potential issues with Lithium use?
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
How should a pressure immobilisation bandage be placed?
- 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
What are the criteria for safe removal of a PIB? what is the post removal managent
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
What are the Hunter criteria for Serotonin syndrome?
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
Who is at greater risk for Paracetamol toxicity?
Hyperactive enzymes
- Alcoholics
- Epileptics on Phenytoin or Carbamezepine
- Rifampicin use
- Phenobarbitol
Depleted Glutathione
- Eating disorders
- Prolonged starvation
- HIV
- Cystic fibrosis
What are the criteria for for referral to a liver transplant centre for panadol overdose?
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
What are some other criteria for liver transplant in paracetamol overdose that may not be immediate?
- 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
