Poisoning and Overdose

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Introduction

Many medications, toxins, and other substances can have profoundly significant, even letal, effects at a high-enough dose. Identifying the 'poisoned patient', determining the cause, and treating appropriately are important skills for health care providers. 

 

Ask for help; overdoses can be very difficult to manage. The majority of intoxications can managed supportively.

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Numerous chemicals can have impoact on health, either acutely or chronically. Some common toxins important for health care providers to be aware of include:

Medications

 

Other Toxins

household products

  • cough/cold preparations, hydrocarbons, cosmetics, plants, cleaning products

 

Information can be gathered from Poisonex or from company websites. A key number to call is Poison Control, staffed largely by nurses and pharmacists.

 

"When an activity poses a threat to human health or the environment, precautionary measures should be taken, even when the cause and effect relationship is not fully established scientifically..." the Precautionary Principle

 

 

 

Toxidromes

Toxidromes are combinations of vital signs and clinically obvious end-organ manifestations, including pupils and skin. They provide clues to diagnosis and direct  management.


However, it is important not to depend on them. Not all toxins cause a toxidrome, mixed ingestions can cancel each other out, and underlying medical conditions or regular prescription meds can influence manifestations. The differential includes other types of shock.

 

  • sympathomimetic
  • sympatholytic
  • anticholinergic
  • cholinergic
  • opioid

sympathomimetic toxidrome

SNS overstimulation results in an elevation of vitals: fight or flight

  • diaphoresis
  • hypertension
  • tachycardia or arrhythmias
  • increased respiratory rate
  • mydriasis
  • hyperreflexia
  • delusions, paranoia

sympatholytic toxidrome

  • hypotension
  • bradycardia
  • hypothermia (less movement, lying on cold floors)
  • decreased RR (indication for narcan)
  • miosis
  • decreased BS

anticholinergic toxidrome

most common; results from removal of vagal tone

  • hyperthermia
  • tachycardia
  • big, dilated pupils (mydriasis)
  • hypertension
  • respiratory depression
  • dry mouth
  • dry, hot skin
  • tachycardia, arrhythmias, CV collapse
  • decreased bowel sounds, ileus, constipation
  • urinary retention
  • confusion, agitation
  • delerium, hallucinations
  • hyperreflexia, myoclonus
  • ataxia
  • seizures, coma
  • ECG: sinus tachy, prolonged PR, QRS, QT intervals; RBBB, ST elevation in leads V1-V3

mad as a hatter, red as a beet, dry as a bone

 

causes

  • tri-cyclic antidepressants (life-threatening over 10mg/kg)

cholinergic toxidrome

nicotinic and muscarinic effect


  • fluids pouring from every orifice: salivation, lacrimation, urination, diaphoresis, bronchorrea (what kills people early on)
  • bradycardia, hypotension
  • emesis, urinary and fecal incontinence
  • neuro: miosis, altered LOC, seizures

 

causes: organophosphate and carbamate pesticides, some mushrooms, nerve gas

people often die of bronchorrhea

atropine an antidote

opioid toxidrome

  • decrease in vitals
  • stupor, seizures, coma, respiratory depression
  • miosis,
  • dry skin
  • urinary retention
  • decreased bowel sounds
  • hyporeflexia

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The poisoned patient

Ensure healthcare/rescuer safety - acids/bases, gases, organophosphates

  • history
  • physical exam
  • investigations

History

Collateral history is extremely important in approaching the poisoned patient.

 

symptoms

  • level of consciousness
  • blurred vision
  • seizure

surrounding events

  • drug(s) ingested
  • amount (how many empty bottles?)
  • when taken
  • route
  • circumstances (intentional vs unintentional; occupational, recreational, suicidal, accidental)
  • did they spit it out? swallowed? vomited?
  • suicide note or phone call?

medical and psychiatric history

  • worsening depression
  • previous suicide attempts

medications

precription medications

social history

  • alcohol, drug abuse
  • social supports

 

Physical Exam

Vitals

  • GCS, HR, BP, O2 sat, temp, chem strip

Be brief but attentive. Assume nothing. Examine:

  • pupils
  • lungs
  • heart
  • GI 
  • mucous membranes: dry or wet (armpit specific) for ruling out pure anticholinergic
  • skin
  • GU: are they making urine?

in particular, pay attention to:

  • signs of trauma, track marks

 

Investigations

blood tests

  • CBC-diff
  • electrolytes
  • urea and creatinine (can patients clear the drug)
  • glucose
  • ALT, AST, ALP, billi, GGT
  • INR, PTT
  • Ca, Mg, PO4
  • arterial blood gas
  • creatinine kinase
  • beta hCG (if applicable)
  • osmolar gap
  • anion gap


tox screen (within 72 hours) - be aware of many false positives or negatives

  • ethanol
  • acetaminophen 
  • salicylates
  • methanol
  • ethylene glycol
  • digoxin
  • other medication levels

urine tox screen has limited utility

 

ECG

CXR (aspiration pneumonitis/pneumonia)

CT head

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Treatments

When contemplating treatment, consider:

  • ABCs
  • preventing absorption
  • enhancing elimination

ABCs

Perform a complete set of vitals  (HR/BP/T/GCS/O2 sat) and immediately correct life-threatening abnormailites. 

Airway/breathing: intubate if GCS <8, with severe hypoxia or hypercapnia, and with hemodynamic instability

Circulation: 2 large bore IV's, equipped with pressure bags


coma/depressed level of consciousness

Important antidotes to consider (DON'T Forget):

  • dextrose (hypoglycemia)
  • oxygen
  • naloxone: use for respiratory depression, not decreased level of consciousness (people who go into withdrawal will take off)
  • thiamine
  • flumazenil (benzodiazepine antidote)

anticiapte seizures/ CV collapse

 

secondary survey

Complete exam

  • signs of trauma
  • pupils
  • skin: temp, colour
  • bowel sounds
  • CNS

other A: antibiotics: 1qm Ceftriaxone

Prevent absorption

Induction of emesis is no longer recommended

 

activated charcoal

  • most effective within a couple hours
  • liquid meds likely no benefit
  • does not bind Li, Pb, Fe, alcohols
  • children do not like it
  • vomiting and aspiration is an important potential risk
  • take at 0.5-1.0 g/kg

 

gastric lavage has limited indications, and can be especially difficult in children.

  • ingestion within an hour
  • lethal drug for which there is no antidote

 

whole bowel irrigation with PEG

  • provide via NG tube at 35ml/kg/hr until clear rectal effluent
  • useful for:
    • slow release/enteric coated medications
    • toxins that are not adsorbed to AC (ie iron)
    • body packers/stuffers (ie drug mules)
  • contraindications: airway, GI pathology, hemodynamic instability

Enhance elimination

urine alkalinization (for salicylates)

multiple dose activated charcoal (gut dialysis)

hemodialysis

  • alcohols, ASA, lithium, theophylline, iron

hemoperfusion

  • theophylline, carbamezapine, phenytoin, barbituates

caustic ingestion: no charcoal (don't cause vomiting); don't cause lavage

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Specific Agents

  • toluene
  • Tab 2

Toluene

found in glues, cements, paints/thinners: Glue sniffing

  • mental obtundation
  • appearance of intoxication
  • metabolic acidosis

can be confused with ethylene glycol

DDx:

ASA

CO

 

supportive therapy

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Resources and References

US National Library of Medicine ToxNet

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