DESCRIPTION
Frequently encountered poisonings in adults include:
- analgesics
- cardiodepressants
- hydrocarbons
- anticonvulsants
- pesticides
- toxic alcohols e.g. methanol, ethylene glycol
- anti-infectives
- sedatives, antidepressants and antipsychotics
- antihistamines
- iron
- ethanol/alcohol
- irritants and corrosives
Suspect intentional ingestion in adults.
DIAGNOSTIC CRITERIA
Clinical
Can be divided into ‘toxidromes”:
Cholinergic: e.g. organophosphates
- salivation
- diarrhoea
- lacrimation
- vomiting
- urination
- bronchorrhoea
- miosis (pinpoint pupils)
- bradycardia
Salicylism: e.g. aspirin
- tachypnoea
- agitation
- metabolic acidosis
- coma
- seizures
Anticholinergic: e.g. antihistamines, amanita pantherina, atropine
- fever
- dry/warm skin
- ileus
- blurred vision
- flushing
- mydriasis (dilated pupils)
- tachycardia
- coma
- urinary retention
- hallucinations and seizures
Sedative-hypnotic: e.g. alcohol, benzodiazepines
- obtundation or coma
Opiates: e.g. morphine
- miosis (pinpoint pupils)
- decreased bowel sounds
- respiratory depression
- hypothermia
- bradycardia
- altered (decreased) mental status
- hypotension.
Dystonic reaction: e.g. haloperidol
- torticollis
- opisthotonus
- intermittent spasms and tongue thrusting
Sympathomimetic: e.g. cocaine, amphetamines
- hypertension
- agitation
- tachycardia
- sweating
- hyperthermia
- dilated pupils
Sympathomimetic toxidrome partly resembles anticholinergic toxidrome, i.e. fight, flight and fright response, however the sympathomimetic toxic patient is sweaty as opposed to hot dry skin seen with anticholinergic toxicity.
Toxic alcohols: e.g. ethylene glycol, methanol
- metabolic acidosis
- hypoglycaemia
- increased osmolar and anion gap
- convulsions
- visual disturbances (methanol)
- renal failure (ethylene glycol)
- depressed level of consciousness.
GENERAL MEASURES
It is very important to ascertain if a TOXIC DOSE has been taken BEFORE instituting any potentially harmful decontamination procedures in an asymptomatic patient.
Take a complete and accurate history, ascertain all relevant facts and do a complete clinical examination. A high index of suspicion is important.
Obtain a collateral history, especially for patients with impaired consciousness. A special effort should be made to obtain tablets, packets, containers, etc. to identify agents involved.
Stabilise the patient and monitor basic clinical parameters, i.e.:
- blood pressure and heart rate
- hydration
- airway and ventilation
- neurological status
- temperature
- glucose
Persistent or prolonged seizures may require medical management. Phenytoin should not be used in cases of poisoning due to substances known to be cardiotoxic e.g. tricyclic antidepressants, or where there is evidence of clinical cardiotoxicity.
Prevent physical injury in the restless - avoid excessive sedation.
Limit toxicology investigations to those that may influence/alter management. It is important to note the time after ingestion when blood was taken in order to correctly interpret results (e.g. paracetamol, iron levels).
DECONTAMINATION
Limit further exposure to poison for the patient and protect healthcare workers where necessary.
- Topical exposure
In case of skin exposure, remove clothes and wash the body. Showering may be useful.
Remove eye contaminants, especially alkalis, acids and other irritants, by continuous irrigation of the eye with sterile water or normal saline for 15–20 minutes. Analgesic eye drops may be required to perform this adequately.
2. Gut decontamination
Methods of gut decontamination include:
- Gastric lavage
- Activated charcoal administration
- Whole bowel irrigation
Gastric lavage
If deemed beneficial, it should only be performed by experienced staff and within 60 minutes of ingestion.
Can be considered for cases with:
- potentially life-threatening ingestions AND
- a protected airway i.e. fully awake and cooperative or intubated with a depressed level of consciousness.
Gastric lavage is contra-indicated after ingestion of corrosive substances and volatile hydrocarbons such as paraffin.
Technique:
Place patient in left lateral head down position
Insert orogastric tube if possible, with largest bore and rounded tip.
Insert 200ml warmed water or normal saline, and aspirate.
Continue until recovered solution is clear of particulate matter.
Activated charcoal
May reduce systemic absorption of a variety of poisonous substances. The greatest benefit is achieved if activated charcoal is given within one hour after ingestion; however where gastric emptying is delayed by certain substances, there may be a longer period of time in which it is effective. Activated charcoal must only be given in cases where the airway is protected; i.e. fully awake and cooperative patient or intubated with a depressed level of consciousness.
Repeated doses of activated charcoal (i.e. 50 g every 4 hours) are effective in enhancing elimination of substances that undergo enterohepatic circulation, e.g. carbamazepine, dapsone, phenobarbitone, quinine or theophylline overdose.
| Charcoal may be useful if these poisons are taken in toxic dose | Poisons where charcoal is ineffective and should not be given |
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- Charcoal, activated, oral, 50 g (equivalent to 36 level medicine measures) diluted in 100 mL water.
- When mixing, add a small amount of water to charcoal in a container.
- Cap and shake container to make a slurry and then dilute further.
Whole bowel irrigation
Whole bowel irrigation can be done for potentially toxic ingestions of substances that are:
- not absorbed by activated charcoal (e.g. iron and lithium)
- sustained-release and enteric-coated products
- or for removal of illicit drugs in body packers
Patients must have a protected airway i.e. fully awake and cooperative or intubated with a depressed level of consciousness.
- Polyethylene glycol (PEG) balanced electrolyte solution, NGT,
- 1500–2000 mL/hour.
- Continue until rectal effluent is clear.
OTHER TREATMENT MODALITIES
Urinary alkalinisation (e.g. severe salicylate or tricyclic antidepressant poisoning)
Caution
This is a high risk procedure and should only be performed in consultation with a specialist.
Haemodialysis
Patients with symptomatically severe poisoning e.g. due to salicylates, lithium, ethylene glycol, methanol, ethanol and theophylline, may benefit from dialysis (http://www.extrip-workgroup.org/).
Refer patient to a hospital with dialysis facilities.
Antidotes
There are a limited number of antidotes for poisoning by certain substances, e.g. N-acetylcysteine for paracetamol, naloxone for opioids. Each antidote has specific criteria and indications for use.
Once medically stable:
Assess and manage intentional poisoning – self-harm or harm by others:
- take a history of circumstances around the poisoning, substance use and mental illness, and examine the mental state
- assess further suicide risk – see PHC STGs and EML Suicide Risk Assessment
- refer to social, psychological and/or psychiatric services
Assess and manage a substance use disorder
- quantify the amount of substance used and related harms, e.g. with ASSIST (http://www.who.int/substance_abuse/activities/assist/en/) or DUDIT (https://paihdelinkki.fi/sites/default/files/duditmanual.pdf) rating scales and discuss with patient
- provide brief intervention with motivational interview
- refer for rehabilitation
REFERRAL
- Severely ill patient for ventilatory/circulatory support.
- Relevant diagnostic testing not available, e.g. paracetamol levels, acid/base assessment.
- Relevant medication/antidote not available.
- Dialysis/haemoperfusion required.