.(dr.muhamad shaikhane)

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  • 1. :Prepared by .Dr.Mohamed Shekhani.References: Davidson PP of Medicine

2. :Introduction Poisoning is a major cause of death in young adults& 10% ofhospital admissions. Most deaths occur before patients reach medical attention&mortality is much 1 hour after overdose inmost circumstances,EXCEPT when delayed-release preparation has been taken or when gastric emptying may be delayed. 16. Activated charcoal Some toxins do not bind to activated charcoal so it will not affecttheir absorption. In patients with an impaired swallow or a reduced level ofconsciousness, the use of activated charcoal, even via a nasogastrictube, carries a risk of aspiration pneumonitis. This risk can be reduced but not completely removed byprotecting the airway with a cuffed endotracheal tube. Multiple doses of oral activated charcoal (50 g every 4 hours) mayenhance the elimination of some drugs at any time afterpoisoning and are recommended for serious poisoning with somesubstances . 17. Activated charcoal They achieve their effect by interrupting enterohepatic circulationor by reducing the concentration of free drug in the gut lumen, tothe extent that drug diffuses from the blood back into the bowel tobe absorbed on to the charcoal: so-called GIT dialysis. A laxa-tive is generally given with the charcoal to reduce the risk ofconstipation or intestinal obstruction by charcoal briquetteformation in the gut lumen. Recent evidence suggests that single or multiple doses ofactivated charcoal do not improve clinical outcomes after poisoningwith pesticides or oleander. 18. SUBSTANCES NOT BOUND BYCHARCOAL Alcohols And Heavy MetalsGlycols Iron Corrosives Lead Alkalis Lithium Acids Mercury Cyanide Hydrocarbons Saline Cathartics 19. Gastric aspiration & lavage Gastric aspiration and/or lavage is now very infrequentlyindicated in acute poisoning, as it is no more effective thanactivated charcoal, and complications are common, especiallyaspiration. Use may be justified for life-threatening overdoses of somesubstances that are not absorbed by activated charcoal 20. Whole bowel irrigation This is occasionally indicated to enhance the elimination of ingestedpackets or slow-release tablets that are not absorbed by activatedcharcoal (e.g. iron, lithium), but use is controversial. It is performed by administration of large quantities ofpolyethylene glycol and electrolyte solution (12 L/hr for an adult),often via a nasogastric tube, until the rectal effluent is clear. Contraindications include inadequate airway protection,haemodynamic instability, gastrointestinal haemorrhage,obstruction or ileus. Whole bowel irrigation does not cause osmotic changes but mayprecipitate nausea and vomiting, abdominal pain and electrolytedisturbances 21. Urinary alkalinisation Urinary excretion of weak acids& bases is affected by urinary pH,which changes the extent to which they are ionised. Highly ionised molecules pass poorly through lipid membranes andtherefore little tubular reabsorption occurs and urinary excretionis increased. If the urine is alkalinised (pH > 7.5) by the administration ofsodium bicarbonate (e.g. 1.5 L of 1.26% sodium bicar-bonate over 2hrs), weak acids (e.g. salicylates, methotrexate , herbicides 2,4-dichlorophenoxyacetic acid and mecoprop) are highly ionised andso their uri-nary excretion is enhanced. This technique should be distinguished from forced alkalinediuresis, in which large volumes of fluid with diuretic are given inaddi-tion to alkalinisation(no longer used because of the risk offluid overload). 22. Urinary alkalinisation Urinary alkalinisation is currently recommended for patientswith clinically significant salicylate poi-soning when the criteriafor haemodialysis are not met It is also sometimes used for poisoning with methotrexate. Complications include alkalaemia, hypokalaemia, occasionallyalkalotic tetany. Hypocalcaemia is rare. 23. Haemodialysis & haemoperfusion These can enhance the elimination of poisons that have a smallvolume of distribution & a long half-life after overdose, useful whenthe episode of poisoning is sufficiently severe to justify invasiveelimination methods. The toxin must be small enough to cross the dialysis membrane(haemodialysis) or must bind to activated charcoal(haemoperfusion) . Haemodialysis may also correct acidbase and metabolicdisturbances associated with poisoning 24. Antidotes Are available for some poisons Work by a variety of mechanisms: for example: Specific antagonism (e.g. isoproterenol for blockers) orPharmacological antagonism( flumazenil for benzodiazepines &nalorphine for opoids) Chelation (e.g. desferrioxamine for iron) Reduction (e.g. methylene blue for dapsone). 25. Supportive care For most poisons, antidotes & methods to accelerate eliminationare inappropriate, unavailable or incompletely effective. Outcome is dependent on appropriate nursing & supportive care,& on treatment of complications. Patients should be monitored carefully until the effects of anytoxins have dissipated. 26. :Study SCQs 1. In Poisoning all are true except:: A. The most common cause of death in young adults. B. The most common cause of hospital admissions. C. Most die before reaching hospital. D. In-Hospital Mortality should be less than 1%. E.The most common cause of death in elderly persons. 27. :Study SCQs 2.The most way of poisoning is: A.Accidental. B.Intentional. C. Agricultural products intake. D. Alcolol. E. Opoid intake. 28. :Study SCQs 3.Common drugs involved in poisoning include all except: A.NSAIDs. B.Acetaminophen. C. Antidepresants. D.Lead. E.Alcohol. 29. :Study SCQs 4. Poisons with serious effects requiring urgent actionsinclude all except: A.Acetaminophen. B.Ethylene glycol. C.Oral contraceptives. E. CO. 30. :Study SCQs 5.Poisoning is recognized by the following toxidromesexcept: A.Anticholinergic. B. Adrenergic. C.Cholinergic. D.Stimulants. E.Opoid. 31. :Study SCQs 6.Regarding poisoning in elderly,all are true except: A. Commonly caused by intentional poisoning. B. Mortality in higher. C. Psychiatric disease as a cause is less than in the young. D. Higher risk of recurrent attempts if due to chronicillnesses. E. Toxic prescriptions are common. 32. :Study SCQs 7. Drug level as part of management of poisoning isindicated in all except: A.Acetaminophen. B. Oral hypoglycemic. C.CO. D.Iron. E.Digoxin. 33. :Study SCQs 9.All these poisons cause acidosis with normal lactateexcept: A.Aspirin. B.Methanol. C. Ethelene glycol. D.Paraldehyde. E.Iron. 34. :Study SCQs 10.The following are not adsorbed by activated charcoalexcept: A.Cyanide. B.Glycols. C.Aspirin. D.Lead. E.Lithium. 35. :Study SCQs 11.The best management of drug-poisoned patientpresenting within 1 hour is: A.Whole bowel irrigation. B.Tincher ipecan vomint induction. C.Activated charcoal. D.Hemodialysis. E.Hemofiltration. 36. :Study SCQs 12.The antidote that acts by direct pharmacologicalantagonism is: A.Deferoxamine for iron. B.Nalorphine for opoids. C.Alkaline diuresis for salycylates. D.Praladoxime for organophosphorous poisoning. E.Methylene blue for Dapson. 37. :Study SCQs 13.The most urgent treatment of organophosphorouspoisonig is: A.Atropin injection. B.Praladoxime. C.Mechanical ventilation. D.O2. E.Bronchial lavage.