poisoning

ACUTE POISONING IN ADULTS

DR. ALI A. ALLAWI CONSULTANT INTERNIST & NEPHROLOGIST

Acute Poisoning in the Emergency Department

Common - 3-5% of ED attendances2000 Deaths per yearSome of the highest rates of deliberate poisoning in EuropeOften multiple drugsDON’T FORGET ALCOHOL !!

THE IMPORTANCE OF PHARMACOLOGY

“You may experience a difficulty in remembering the antidotes for the various poisons. If so, rest assured that your knowledge of pharmacology is defective. All rational treatment of cases of poisoning is founded on a correct appreciation of the physiological action of drugs.” What to do in cases of poisoning, William Murrell, 1925
NPIS

Edinburgh

General Management -History



Applies to ANY episode of Poisoning WHAT HOW MUCH (Ideally mg/Kg) WHEN WHAT ELSE (Including Alcohol) WHY Use Paramedics, friends, relatives, anyone!!

General Management -1

A (Airway)B (Breathing)C (Circulation)D (Disability-AVPU/ Glasgow Coma Scale)DEFG ( Don’t ever forget the Glucose)GET A SET OF BASIC OBSERVATIONS

General Management -2

Use all your senses, search for the clues LOOK Track Marks Pupil Size FEEL Temperature, Sweating SMELL Alcohol

APPRAISAL OF THE POISONED PATIENT

history from patienttablets / circumstances foundclinical features (“TOXIDROMES”)Opiateanticholinergicstimulantmetabolic acidosis
NPIS

Edinburgh

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Downloaded from: StudentConsult (on 26 December 2010 09:41 PM)

Specific Management Options-1

DECREASING DRUG ABSORPTION Gastric Lavage ( Unpopular - need to protect the airway, may push drug through pylorus into small bowel.) Absorbants ( Activated Charcoal , usually within 1 hour of ingestion, longer repeated doses in drugs that delay gastric emptying e.g. Aspirin)

Gastric lavage Ward 3, Royal Infirmary of Edinburgh, 1973 (courtesy of Alex Proudfoot)

PREVENTION OF ABSORPTION

activated charcoal binds non-specifically binds about 1/10 of charcoal weight (charcoal dose 50 g in an adult) Slow release products
NPIS

Edinburgh

ACTIVATED CHARCOAL

timing - use within 1 hourairway - don’t if problemsagent - eg iron, lithium, hydrocarbons NOT bound NPIS

Edinburgh

Specific Management Options -2

INCREASING DRUG ELIMINATION Alkaline Diuresis (Aspirin) Haemodialysis (Aspirin)

Specific Management Options - 3


ANTAGONISING THE EFFECTS OF THE POISON Desferrioxamine (IRON) Naloxone (OPIATES) N Acetylcysteine (PARACETAMOL)

Specific Poisons- Paracetamol

Commonest drug used50% of all Self Poisoning Episodes100- 200 deaths per yearDANGEROUS AND PEOPLE DON’T KNOW IT. YOU FEEL WELL AND THEN THE LIVER FAILURE SETS IN..

Paracetamol-Normal Metabolism

Paracetamol converted to: N-Acetyl-p-benzoquinonamine (TOXIC) This is conjugated with Glutathione Glutathione stored in the body Produces a NON TOXIC metabolite

Paracetamol Metabolism in Overdose

Glutathione stores are used up by the excess Paracetamol Toxic Metabolite build up Binds IRREVERSIBLY to Hepatic Cell membranes Resulting in LIVER NECROSIS

Paracetamol Overdose-management

Initial ABC ( usually well systemically) Get a good history TIME TAKEN, AMOUNT Any other medication History of Liver disease N-Acetylcysteine. Shown to be advantageous if given in the first 10 hours

N - Acetylcysteine

Specific antidote used for Paracetamol Provides the Sulphydryl groups needed to increase the availability of Glutathione So that Body can turn the TOXIC metabolite into the non toxic form and prevent Liver Cell Damage and NECROSIS Problem: Not shown to be effective after 15 hours

Paracetamol Management

Able to measure levels of Paracetamol in the blood. Helps to guide whether amount taken is enough to be Hepatotoxic IF IN DOUBT start treatment before the Paracetamol levels get back to save time

Paracetamol Management-Pitfalls

Patients with Liver Disease/ Alcoholics Depleted stores of Glutathione will start to get toxic build up sooner than healthy people Staggered Overdoses Levels unreliable After 15 hours- what do you do??

Paracetamol Management

TIMEBOMB WAITING TO HAPPEN IF HAVE LATE PRESENTATION HAVE TO MONITOR FOR IMPENDING LIVER FAILURE REFER TO SPECIALIST LIVER UNIT PEOPLE DIE FROM THIS

Opiate Poisoning- Features

Common (particularly in BRI) Heroin, Methadone, Analgaesics in Elderly Action on the mu receptors giving the effects in overdose. 1. PINPOINT PUPILS 2. RESPIRATORY DEPRESSION 3.COMA

Opiate Overdose-Management

INITIAL MANAGEMENT A B C D

Opiate Overdose-Management 2

NALOXONE Opioid antagonist High Affinity for the opiate receptors Little other effects Rapid onset Effects last 2-4 hrs, may need repeated doses Give I-M or I-V

Salicylate (Aspirin) Poisoning

Toxicity occurs due to disturbance in Acid-Base Balance 1. Respiratory Alkalosis 2. Metabolic Acidosis

Aspirin Poisoning- mechanism 1

1.Direct stimulation of the respiratory centre makes you overbreathe. Hyperventilation and Respiratory Alkalosis. 2. Kidney attempts to compensate for the alkalosis by excreting alkali to give you a metabolic Acidosis 3. Aspirin inhibits the normal metabolic pathways

Aspirin poisoning- mechanism 2

3. Aspirin inhibits the normal metabolic pathways, so you get failure of the normal metabolism of CHO, Fats and Protein. Build up of Organic Acids KETONES, LACTATE AND PYRUVATE CAUSES MORE METABOLIC ACIDOSIS METABOLIC ACIDOSIS, BAD NEWS

Aspirin Poisoning -Clinical Features

COMMON FEATURES: Vomiting, Dehydration, Tinnitus, Vertigo Sweating, Bounding pulses, Hyperventilation UNCOMMON FEATURES: Confusion, Disorientation, Coma, Convulsions Haematemesis, Hyperpyrexia, clotting abnormalities, renal failure

Aspirin Overdose-Management

Initial Supportive therapy. If small amounts and asymptomatic may need no treatment Management tailored according to the amount taken Able to take Salicylate levels to help guide treatment options

Aspirin Management - General

A B C D (EFG)

Aspirin Management - Specific

When extremely high levels of Aspirin have been ingested and the patients are symptomatic steps may be taken to- 1. DECREASE ABSORPTION 2. INCREASE DRUG ELIMINATION

Aspirin- Decreasing absorption

Activated Charcoal Given in those who have taken more than 250mg/Kg body weight less than 1 hour ago Gastric Lavage May be considered in those who have taken more than 500mg/kg body less than 1 hour ago. Steps must be taken to protect the airway

Aspirin-Increasing Drug Elimination

Urinary Alkalinisation If you increase urinary pH from 5 to 8 there is a 10-20 fold increase in the renal salicylate clearance This is done by giving an infusion of Sodium Bicarbonate. Care must be taken because this in itself is dangerous and can cause severe Acid Base Disturbances

Aspirin- Increasing Drug Elimination

HAEMODIALYSIS Used in severe life threatening overdose Aims to correct the Acid Base disturbances while removing the Salicylate

Tricyclic Antidepressants

Seen relatively frequently Can be fatal Can be very symptomatic, effects made worse by alcohol Main effects are on the Heart and Brain Effects are 1. Anticholinergic 2. Quinidine like

TCA Overdose- Clinical features

ANTICHOLINERGIC EFFECTS Dry Mouth, Dry Eyes, Dilated Pupils, Urinary Retention, Blurred Vision, Dizziness, Palpitations, Pyrexia without sweating CNS Effects- Confusion, Delerium, Coma, Convulsions, Myoclonus and Respiratory Depression

TCA Overdose Clinical Features

Cardiac Toxicity (quinidine effects) Heart Block, Asystole, Bradycardia, Tachycardia, Ventricular Dysrythmias ECG Changes - broadening of QRS complex, Widened QT Interval

TCA Overdose- Management 1

Mainstay of initial management is Supportive. Try not to give other drugs ontop with a few specific exceptions A- May need intubating B C- Give IV fluids if low BP D -Control convulsions with Diazepam



TCA Overdose Management 2


Activated Charcoal if more than 4 mg/Kg within 1 hour. N.B WATCH OUT FOR THE AIRWAY Correct Hypoxia with Oxygen Correct Acidosis with Na Bic Correct any arrythmias with Na Bic (i.e start by controlling the acid base disturbance)

QUESTIONS

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SUMMARY

Get as much history as you can, know your enemyMainstay of any poisoning is SupportiveDon’t Forget the ABCFor specific substances there maybe antidotesFor Specific circumstances consider decreasing the absorption or increasing the elimination of the drug.