Definitions

• Poison: Any substance that can cause severe organ damage or death ifingested, breathed in, or absorbed through the skin

• Toxin: A poisonous substance, especially a protein, that is produced byliving cells or organisms and is capable of causing disease when introducedinto the body tissues but is often also capable of inducing neutralizingantibodies or antitoxin.

Definitions

• Toxicity: Degree to which a substance can damage anorganism.• Acute toxicity involves harmful effects in an organism through a single

or short-term exposure.

• Subchronic toxicity is the ability of a toxic substance to cause effects formore than one year but less than the lifetime of the exposed organism.

• Chronic toxicity is the ability of a substance or mixture of substances tocause harmful effects over an extended period, usually upon repeatedor continuous exposure, sometimes lasting for the entire life of theexposed organism.

Definitions

• Toxicology: The study of the nature, effects, and detection of poisons(toxins) and the treatment of poisoning.

Treatment of Poisoning: Principles

Resuscitation Risk Assessment Supportive Care and Monitoring

InvestigationsDecontamination

Enhanced Elimination Antidotes Disposition

Resuscitation: The ABCDE way!Check for Goal Possibility Possible Measures

Airway Maintain patency Patent/Obstructed Position: Left lateral, Head downSuctioningIntubation +/- Guedel’s Airway

Breathing Maintain adequate oxygenation and ventilation

Spontaneous/ApnoeicSpO2 levels

Start Oxygen at 2L/min via face maskIntubation +/- Guedel’s AirwayCheck for falling SpO2

Circulation Maintain perfusion to vital organs

Feel for PulsesBP recordable(?)

Attach Monitor, look for rhythm consider inotropes (dobutamine)Start Crystalloids (Normal Saline preferred) +/- Consider vasopressors (adrenaline)

Resuscitation: The ABCDE way!Check for Goal Possiblity Possible Measures

Disability Assess level of Consciousness;Correct life threatening conditionsInstitute Resuscitative Antidotes

Glasglow Coma Scale or AVPU scaleHypoglycaemia; Hypethermia; Seizure(focal/generalised)Antidotes

Dextrose bolus injection; active cooling; benzodiazepam(diazepam)

Exposure Assess Toxidromes1 Cholinergic/AnticholinergicDelirium, Agitation, Neuroleptic Malignant Syndrome

Manage Accordingly

1Toxidromes: Physiologically based abnormalities that are known to occur with specific classes of substances and typically are helpful in diagnosis

Risk Assessment

• Distinct Quantitative Cognitive Step

• Ascertain:• Agent(s)• Dose(s)• Time since ingestion• Clinical features and progress• Patient factors and co-morbidities

• Methods:• History by patient himself/herself; attendants• Missing medicines at home, previous medical records, agents available at

home

Supportive Care and Monitoring: Rationale

• Major causes of poisoning morbidity and mortality are acute effectsof poison on cardiovascular, central nervous or respiratory systems:supportive care thus required

• Monitoring is essential to detect the progress of the intoxication andthe timing of institution, escalation and withdrawal of supportive careand other measures.

Supportive Care and Monitoring

• Initially should be done in ED

• Duration of Monitoring determined by:• Agent(s) ingested

• Formulation involved

• Disposition from ED depends on:• Current clinical status

• Expected clinical status

• Patient shifted to either Emergency Observation Unit or Intensive Care Unit

Supportive Care Measures

Investigations in Poisoning or Overdoses

• Are either:• Screening Tests:

• Qualitative and quantitative evaluation for active ingredient, its metabolite or other affected biochemical parameters

• May direct therapy

• Blood, Urine, Stool, Other body fluids e.g. gastric aspirate

• Specific Tests• Should be requested selectively, if anticipated to assist risk assessment or management

• Includes Complete Blood Counts, Liver Function Test, Renal Function Test, Arterial Blood Gas Analysis, Chest X-ray

Decontamination

• High Hazard Potential: Not to be used routinely

• Clinical judgment based on potential benefits, potential risks and available resources

• Absorption virtually completed within 1 hr- so decontamination should be done as early as possible

Decontamination

Induced Emesis Gastric Lavage Activated Charcoal Whole Bowel Irrigation

Syrup of Ipecac Sequential administration and aspiration of small volumes of fluid from stomach via a orogastric tube

Single Dose Polyethylene glycol- electrolyte solution (PEG-ELS)

Unreliable Unreliable Reversibly adsorbs most ingested toxins

Rarely performed: Sustained release and Enteric Coated formulations, ORAgent not binding to charcoal and good clinical outcome not expected with supportive care and antidote administration and the patient presentsbefore established severe toxicity

Not Recemmended

Abandoned from most of the ED

Indicated within 1 hr of ingestion

Major risk: pulmonary aspiration

50 g (adults) or 1g/kg (child)

Potential Indications:Iron overdose >60 mg/kg; Slow release potassium chloride ingestion >2.5 mmol/kg; Life-threatening slow-release verapamil or diltiazem ingestions; Symptomatic arsenic trioxide ingestion; Lead ingestion; Body packers

CAUTION!!

• Do not try Activated Charcoal for:• Hydrocarbons and Alcohols: Ethanol, Isopropyl Alcohol, Ethylene glycol,

methanol

• Metals: Lithium, Iron, Potassium, Lead, Arsenic, Mercury

• Corrosives: Acids, Alkali

Enhanced Elimination

• Increase the rate of removal of an agent with the aim of reducing the severity and duration of clinical intoxication

• In practice, these techniques are useful only in the treatment of poisoning by a few agents that are characterised by:• Severe toxicity

• Poor outcome despite good supportive care and antidote administration

• Slow endogenous rates of elimination

• Suitable pharmacokinetic properties

Techniques for Enhanced Elimination

Multiple Dose ActivatedCharcoal (AC)

Urinary Alkalinisation Haemodialysis, Hemofiltration, Plasmapheresis, Exchange Transfusion

Charcoal Hemoperfusion

Repeated dose AC – fills GIT with AC – acts byinterruption of entero-hepatic circulation and gastrointestinal dialysis

Alkaline urine promotes the ionisation of highly acidic drugs and prevents reabsorptionSodium bicarbonate, bolus + infusion

CarbamazepineDapsonePhenobarbitoneQuinineTheophylline

PhenobarbitoneSalicylate

LithiumMetformin Lactic AcidosisPotassiumSalicylateTheophyllineToxic alcoholsValporic Acid

Theophylline

Antidotes

• Antidotes are drugs• have specific indications, contraindications, optimal administration methods,

monitoring requirements, appropriate therapeutic end-points and adverseeffect profiles.

• The indications to administer an antidote to an individual patient arebased upon a risk-benefit analysis.

• An antidote is administered when the potential therapeutic benefit isjudged to exceed the potential adverse effects, cost and resourcerequirements.

• An accurate risk combined with pharmaceutical knowledge o f theantidote is essential to clinical decision-making.

Few Antidotes…Poison/Overdose Antidote

Organophosphate Atropine

Atropine Physostigmine

Mehtanol Ethanol and fomepizole

Cyanide Thiosulfate

Opioids Naloxone

Beta agonists, Theophylline Esmolol (Beta-blocker)

Digoxin Digoxin immune Fab

Heparin Protamine

Warfarin, Coumarins Vitamin K

Benzodiazepines Flumazenil

Paracetamol Acetylcysteine

Iron and iron salts Desferioxamine

Carbon monoxide Oxygen (Hyperbaric)

Disposition

• Proper Medical and Psychosocial disposition required

• A patient may be:• Discharged from ED after few hours of observation

• Transferred to Emergency Observation Unit

• Transferred to Intensive Care Unit

• Referred to Better Center

Next Class…

• We wil l be discuss ing on some speci f ic poisons

• Ass ignment : What i s the common poisoning oroverdose in your community? F ind out the trade nameas wel l the compound i t conta ins .