General Approach to the Poisoned Patient

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General Approach to the Poisoned Patient
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General Approach

• Every one has a slightly different method of
  dealing with an overdose but mostly we follow a
  general pattern
• Resuscitation
• Risk assessment
• Supportive care
• Decontamination
• Enhanced elimination
• Antidotes (often part of resuscitation)
• Dispostion

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Resuscitation

• This should always be the first step. There is no
  point working out the patients risk from an
  overdose if they are currently in VF
• This follows the layout taught in ACLS courses
  with a few other steps added in

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Resuscitation

• Airway
• Breathing
• Circulation
• Disability
• Assess level of unconsciousness
• Stop seizures (a common effect in overdoses)
• Benzodiazepines such as lorazepam and diazepam
  are used first line for drug-induced seizures
• Dont ever forget glucose

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Resuscitation

• Exposure / Environment
• Correct hyperthermia (T gt 38.5 in overdose most
  often seen with serotonergic syndrome and
  neuroleptic malignant syndrome and is associated
  with CNS dysfunction and multi-organ failure)
• Consider specific antidotes
• A few medications have effective antidotes
• Paracetamol is the most common overdose seen with
  an effective antidote (N-acetylcysteine)

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Risk Assessment

• This determines the patients risk for developing
  complications
• Often the information will need to come from
  ambulance staff and family members

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Risk Assessment Questions to Ask

• What drug has been taken?
• Different drugs have different toxicities
• It is important to know what formulation of drug
  it is
• E.g. Different types of iron tablets contain
  different amounts
• of iron per tablet (ferrogradumet 1-5mg iron,
  ferrotab 65mg)
• How may tablets have been taken?
• If you can not determine the exact number, work
  on worst case scenario
• Eg. if the patient had a script for 100 tablets 2
  week ago, assume they took 100 tablets

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Risk Assessment Questions to Ask

• When were they taken?
• Each drug has a time to peak effect and this
  determines how long a patient should observed
• E.g. if the patient took an overdose of
  paroxetine 18 hours earlier and was asymptomatic
  on presentation, they are not going to develop
  symptoms
• Does the patient have any clinical features of an
  overdose?
• Early onset of symptoms may suggest a large
  overdose
• Does the patient have any co-morbidities that may
  make the effects of a drug worse?
• Someone with severe heart failure will not cope
  with a metoprolol (B blocker) overdose as well as
  they lack the cardiac reserves

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Supportive Care

• This is all that is needed in a majority of cases
• This includes anti-emetics, IV fluids,
  supplemental oxygen, as well as monitoring for
  complications and deterioration

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Decontamination

• Inducing emesis with ipecac, gastric lavage and
  whole bowel irrigation have all previously been
  used to try and remove drugs from the GI tract
  and limit absorption
• All are ineffective
• All have associated risks that outweigh their
  benefits

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Decontamination

• Induced emesis
• No longer ever done
• Risk of aspiration is significant and it does not
  remove drugs effectively
• Gastric lavage
• Involves placing a tube from the mouth to stomach
  and trying to wash the tablets out
• Has a very high rate of aspiration
• It is only done for severe and life-threatening
  overdoses and the patient should be intubated
  prior

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Decontamination

• Whole bowel irrigation
• Consists of giving a course of bowel prep to
  flush the medication out (ie. gives the patient
  diarrhoea )
• Probably ineffective
• Is still used in large iron overdoses as the
  tablets form bezoars in the intestine

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Decontamination

• Activated charcoal
• Has large surface area that can bind drugs and
  theoretically limit absorption
• Limited evidence when given early (lt1 hour),
  ineffective after 1 hour
• High rate of vomiting especially in women
• Causes nasty lung injury if aspirated
• Use is mostly dying out

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Enhanced Elimination

• Rarely done
• 2 most common techniques are
• Dialysis
• Good for alcohols, lithium, aspirin
• Urine alkalinisation
• Traps aspirin in the urine

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Disposition

• When is the patient safe to go home?
• Have they been assessed by psychiatry?