THE POISONED PATIENT

see Poison's information 131126

see Causes of Coma

• Good supportive care is usually all that is required i.e. attention to the ABCs even with unknown poisoning
• Antidotes have a limited role 
• Early charcoal is useful in most circumstances

• Beware of poisons with delayed or prolonged effects

• Beware of children ingesting a 'trivial' adult dose

• Significant poisonings should be managed in ICU

RESUSCITATIVE ISSUES

Airway

• If GCS < 8 or uncontrolled seizure - intubate
• If NGT charcoal required and no gag reflex - intubate

Breathing

• Continuous SpO2 monitoring

• If opiate poisoining (miosis, hypoventilation) - naloxone 50-100 mcg IV increments @ 1 min
• Avoid flumazenil for unknown/polysubstance overdose
• If Hypoventilation/Apnoea not responsive to naloxone - Intubate and ventilate

Circulation

• Continuous BP/ECG monitoring
• IV access

• If arrested - usual ACLS guidelines (but see below) - NB refractory arrest from chloroquine overdose may survive after 2hr CPR (following redistribution of drug) 
• If tachyarrhythmia treat as per ACLS guidelines (consider physostimine in anticholinergic poisoning)
• If bradyarrhythmia treat as per ACLS guidlines
• If hypotensive - fluids +/- pressors 

Specific antidotes if persistently unstable

• If TCA - Sodium bicarbonate 8.4% 1ml/kg 
• If digoxin toxicity - Digoxin Fab Fragments (avoid calcium to treat hyperkalaemia)
• If calcium channel toxicity - 10ml CaCl 10% over 5min (repeat x 2 @ 10 min)
• If beta blocker, calcium channel toxicity - consider glucagon (in addition to usual measures)

• Poisons and haemo-dynamic parameters

Disability

• Check BSL
• Consider other causes of coma or seizures
• Treat seizures (see specific antidotes in poisoning and seizures)
• Poisons and seizures

Exposure

• Hypothermia
• Hyperthermia

• Poisons and disorders of thermoregulation

ASSESSMENT

May require collateral sources - ambulance officer, witness, family, friends, 

Determine nature of poisoning - drug, route, timing and dose - IV track marks, empty pill bottles

• Breath odour
• Sweating
• Pupils/Eyes

• Potent poisons (small dose can kill a child)
• Deceptively benign poisons (have no early symptoms)

Assess for general complications

• Cardiotoxicity (ECG)
• Aspiration pneumonia (CXR)
• Compartment syndrome
• Rhabdomyolysis (CK, urinalysis)

Investigations

• BSL
• Serum drug levels (according to clinical assessment

Screening investigations (if history unreliable)

• Paracetamol/Salicylate level
• ABG (see causes for metabolic acidosis)
• Osmolality (see causes for widened osmolal gap)
• AXR (see radio-opaque tablets)

Urine drug screen do not usually influence management (see limitations of urine drug screening)

Quantitative drug assays rarely correlate with severity or influence management (except in paracetamol, theophylline, lithium, iron poisoning)

DEFINITIVE MANAGEMENT

Obtain expert advice early (even in apparently trivial poisonings)

External decontamination - as required

GI decontamination

• Charcoal 50g (1kg/kg) +/- Sorbitol

• Ideally within 1 hour of ingestion (consider beyond 4 hours with slow-release formulations/lethal toxicity)
• Not useful with Acid/Alkalis, Heavy metals, Elemental poisoning (Lithium, Iron), Hydrocarbons/Alcohols/Organophosphates
• Repeated doses useful in Quinine, Dapsone, Phenobarbitone, TCA, Chloral hydrate, Carbamazepine, Theophylline
• Give by NGT if patient unco-operative (intubate if absent gag reflex or obtunded)

• Ipecac/Induced emesis
  • Rarely indicated (poorly efficacious, risk of aspiration)

• Gastric lavage
  • Rarely indicated (except in large life-threatening ingestion within 1 hour e.g. paraquat, TCA, chloroquine, theophylline, calcium channel blocker)
  • High risk of aspiration - if any doubt airway protection with intubation recommended
  • Technique
    • 32F tube
    • Yankuer sucker available
    • Left lateral, head down position
    • 50-100 ml Volumes of warmed water instilled initially (normal saline in children) then aspirate
    • Repeat clear return
      
• Whole bowel irrigation
  • PEG-ELS/Go-Lytely solution 25ml/kg/hr (=1200-2000ml/hr) via NGT until bowel effluent is clear
  • Administer for 5 hours
  • Useful in Salicylates, Lithium, Iron, Calcium channel blocker, Phenol

Accelerated elimination

• Alkaline diuresis
  • Useful in Salicylate, Barbituates, Lithium, Alcohol, Methanol, Ethylene glycol
  • Bolus - 1-2 mmol/kg (= 1-2 ml NaHCO₃ 8.4%) over 10 min
  • Infusion - 0.5 mmol/kg NaHCO₃ in 1000ml 5% dextrose over 4-6 hrs
  • Add 40 mmol/L K+ when urine output established
  • Aim for urine pH 7.5 

• Charcoal haemo-perfusion
  • Useful in Salicylates, Quinine, Carbamazepine, Theophylline

• Haemodialysis
  • Dialyzable compounds - Salicylate, Isoniazid, Chloroquine, Carbamazepine, Alcohol, Methanol, Ethylene glycol, Amphetamines, Atenolol, Theophylline, Camphor, Heavy metals

ANTIDOTES (obtain expert advice)

• Opioid - naloxone
• Iron - desferroxamine
• Heavy metals - EDTA
• Organophosphates/Carbamates - Atropine
• Pralidoxime - Organosphosphates 
• Methaemogloninaemia - Methylene blue
• Paracetamol - NAC 
• Cyanide - Cobalt EDTA
• Digoxin - Digoxin Fab fragments
• Methanol/Ethylene glycol - Ethanol

RESOURCES

• Poisindex (on computer in Red Doors)
• Goldfrank's Toxicologic Emergencies
• Poison Centre, Women’s & Children’s Hospital (WCH) - ph 131126
• ED Consultant

Do not use MIMS or AMH for toxicology advice

DISPOSITION

Admit to ICU

• Cardio-toxicity (Instability or ECG changes)
• Neurotoxicity (Altered mental state or seizures)
• Theophylline/Quinine

Admit

• Symptomatic patients
• Paracetamol overdose requiring NAC
• Poisons with prolonged effects
• Potent poisons ingested by a child
• Possibility of ingestion of Deceptively benign poisons (have no early symptoms)

Discharge/Refer intentional overdose for psychiatric review if after 4 hours observation 

• Nature of ingestion is clear
• No symptoms
• ECG normal
• Normal haemo-dynamic parameters
• Appropriate  investigations/drug assay normal (see above)

REFERRAL

Psychiatric review - of intentional poisonings