ACUTE POISONING IN ADULTS.ppt

1、ACUTE POISONING IN ADULTS,Leilah Dare SpR Emergency Medicine,Acute Poisoning in the Emergency Department,Common - 3-5% of ED attendances 2000 Deaths per year Some of the highest rates of deliberate poisoning in Europe Often multiple drugs DONT FORGET ALCOHOL !,Summary of Lecture,General Principles i

2、n the Management of ANY Poisoning Specific management options with certain substances Paracetamol Opiates (Heroin, Methadone, Morphine) Salicylates (Aspirin) Tricyclic Antidepressants (e.g Dothiepin),General Management -History,Applies to ANY episode of Poisoning WHAT HOW MUCH (Ideally mg/Kg) WHEN W

3、HAT 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 ( Dont ever forget the Glucose) GET A SET OF BASIC OBSERVATIONS,General Management -2,Use all your senses, search f

4、or the clues LOOK Track Marks Pupil Size FEEL Temperature, Sweating SMELL Alcohol,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

5、 of ingestion, longer repeated doses in drugs that delay gastric emptying e.g. Aspirin),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

6、 (OPIATES) N Acetylcysteine (PARACETAMOL),Specific Poisons- Paracetamol,Commonest drug used 50% of all Self Poisoning Episodes 100- 200 deaths per yearDANGEROUS AND PEOPLE DONT KNOW IT. YOU FEEL WELL AND THEN THE LIVER FAILURE SETS IN,Paracetamol-Normal Metabolism,Paracetamol converted to: N-Acetyl-

7、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 i

8、n 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 Parace

9、tamol 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 Par

10、acetamol 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

11、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,C

12、ommon (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 Affi

13、nity 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 Balance1. Respiratory Alkalosis2. Metabolic Acidosis,Aspirin Poisoning- mechanism 1,1.Direct sti

14、mulation 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 in

15、hibits 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

16、, 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 trea

17、tment 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

18、 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 agoGastric Lavage May be considered in those who have taken more than 500mg/kg body less than 1 hour ago. Steps mus

19、t 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 d

20、angerous and can cause severe Acid Base Disturbances,Aspirin- Increasing Drug Elimination,HAEMODIALYSISUsed 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 sympt

21、omatic, 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 swea

22、ting 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

23、 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

24、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,?,SUMMARY,Get as much history as you can, know your enemy Mainstay of any poisoning is Supportive Dont Forget the ABC For specific substances there maybe antidotes For Specific circumstances consider decreasing the absorption or increasing the elimination of the drug.,