Below is a summary of the chapter content. The topic is described in detail in the Oxford Handbook of Critical Care (see below).

This chapter builds on the Disability (D) and ABCDE approach chapters. You can return to these chapters here:

Intoxication

• Intentional
  (the most severe cases are related to suicidal intent; high to lethal doses of a drug or toxin are used)
• Accidental
  (severity depends on the amount and type of toxin ingested)
  This group includes an iatrogenic error in the confusion about the drug, its dose or form of administration.
  Closing the communication loop and accurately indicating the drug, dose and route of administration reduces these errors.  

Initial approach

The ABCDE approach is always the foundation of the initial approach and diagnosis.

Although intoxication falls under D, there is often a failure already present in the previous steps (e.g. the need to secure the airway and start IPPV, support of circulation with vasoactive agents and fluids), so a systematic approach is always necessary.

In intoxications, we always focus on D and, in addition to neurological deficit and glycaemia levels, we identify:

• the circumstances of intoxication
  (the environment, the place where the intoxication occurred, finding empty blisters, the packaging of the drugs)
• time of intoxication
  (if we are unable to determine this, at least when the intoxicated person was last seen)
• the amount of toxin ingested and route of administration
  (intravenous use will usually be the most acute route)
• the age and weight of the intoxicated person
  (children and older adults are usually more vulnerable)

Part D usually includes laboratory tests to detect the toxin and its amount in the body.
(most often blood and urine, but also, for example, stomach contents or saliva of the intoxicated person).

Clinical presentation

It can vary depending on the toxin, the dose and the time since its use.

In case of ingestion of an unknown substance, it is advisable to focus already during the primary examination on the symptoms of toxidromes, signs specific to one of the toxin groups, allowing to narrow the diagnosis:

• anticholinergic
  (agitation, dry skin and mucous membranes, mydriasis, hyperpyrexia, urinary retention, and in severe cases, convulsions and arrhythmias)
  e.g. antihistamines, antiparkinsonian, antipsychotics, typical antidepressants, spasmolytics, durian and amanita muscarine
  
• sympathomimetic
  (tachycardia and hypertension, hallucinations, mydriasis, hyperreflexia hyperpyrexia, profuse sweating, convulsions in severe cases, hypertensive crisis, hypotension in heart failure)
  e.g. cocaine, amphetamine, methamphetamine, ephedrine, pseudoephedrine, caffeine, teofyline
• opioid
  (opioid triad: depression of the respiratory centre to apnea, quantitative impairment of consciousness to coma, miosis; hypotension, bradycardia, disappearance of peristalsis)
  e.g. morphine and its derivatives, heroin, codeine
  
• sedative
  (quantitative impairment of consciousness, depression of the respiratory centre, hypotension, hypothermia)
  e.g. barbiturates, benzodiazepines, ethanol
  
• serotonin
  (confusion, agitation, tachycardia, tremors, muscle fasciculations, extrapyramidal symptoms, hyperreflexia, sweating and hyperthermia)
  e.g. serotonin reuptake inhibitors SSRI
  
• cholinergic
  (confusion, weakness, miosis, excessive salivation, lacrimation and incontinence, vomiting; in severe cases: bradycardia and convulsions) 
  e.g. organophosphates, some insecticides, nerve gases, physostigmine, some mushrooms
  

Therapy of intoxications

Non-specific procedures

are used to reduce the toxin in the body and prevent further exposure.

Prevention of absorption

Prevention of further absorption according to the route of action of the toxin (e.g. safe evacuation from a contaminated environment in CO intoxication). The most common route of absorption is the GIT system. The following can be used to prevent absorption:

• Lavage of the stomach
  Indicated at short intervals after ingestion (usually within an hour)
  (exceptions may be excessive amounts of the toxin accumulated in the stomach or retardant forms of drugs).
  • A contraindication is the ingestion of alkalis and acids, which would secondarily damage the upper GIT.
  • In case of impaired consciousness or compromise of airway reflexes, always consider securing the airway.
  • Flush with saline warmed to the patient's temperature. (otherwise, there is a risk of hypothermia or hyponatraemia when using aqui).
• Use of activated charcoal
  Again, this depends on the toxin/medication use time, most effective within 6 hours.
  Suitable to repeat the dose and in combination with laxatives.
  A group of poisons that do not bind to activated charcoal (lithium, alcohols, cyanides,...), and its use does not make sense.
• GIT irrigation
  can be used for drugs that do not bind to activated charcoal or are prolonged-release products.
  It belongs to the group promoting toxin elimination.

Elimination support

• Haemodialysis or haemoperfusion
  Some toxins can be removed from the body by the elimination method (e.g. alcohols, salicylates,...).
  Whether a toxin is dialysable can be determined by searching for a Toxnet or consulting a nephrologist.
• Here again, starting as soon as possible increases the chance of a good outcome; do not delay the indication of the method.
• The actual initiation of the method belongs to the hands of the intensivist/nephrologist. It is beyond the scope of this chapter and the required knowledge of the students of the Intensive Medicine course.

Specific antidotes

• The quantity of individual toxins and their antidotes alone (e.g. opioids: naloxone, benzodiazepines: flumazenil, paracetamol: N-acetylcysteine) exceeds the planned learning outcomes. 
• Searching Toxnet is always in order, not only to identify the antidote itself but, more importantly, to determine an up-to-date dosing regimen, as well as to identify non-specific procedures in the therapy of the intoxicated patient. 

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