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HKCP CCM board tutorial Critical Care Toxicology

HKCP CCM board tutorial Critical Care Toxicology. Dr Chan Yan Fat Alfred 18/08/2009. Content. Introduction of clinical toxicology Epidemiology of poisoning in HK General management of poisoning  GI decontamination  Cases discussion Prototypes of toxidrome  Cases discussion

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HKCP CCM board tutorial Critical Care Toxicology

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  1. HKCP CCM board tutorialCritical Care Toxicology Dr Chan Yan Fat Alfred 18/08/2009

  2. Content • Introduction of clinical toxicology • Epidemiology of poisoning in HK • General management of poisoning  GI decontamination  Cases discussion • Prototypes of toxidrome  Cases discussion • Community interest

  3. What is toxicology • Toxicon pharmacon Latin for “Arrow poison”

  4. Sci-tech encyclopedia • Toxicology is the study of the adverse effects of chemical, physical or biological agents on living organisms and the ecosystem, including the prevention and amelioration of such adverse effects.

  5. Encyclopedia of public health “Three laws” of toxicology • The dose makes the poison, byParacelsus • Biologic actions of each chemicals are specific to each chemical, toxidrome • Human beings are animals, LD50 made

  6. Paracelsus (1493-1541) • Alchemist, physician, surgeon and scientist • “All things are poisons, for there is nothing without poisonous qualities…... It is only the dose which makes a thing poison”

  7. Poisoning agents • Drugs • Herbs/ Chinese medicines • Proprietary agent/ health product • Environmental natural substance • Household agents • Food related poisoning

  8. Drug-related poisoning • Overdose of therapeutic drugs self-harm/ accidental/ error/ homicide • Drug-drug/ drug-food interaction • Adulteration • Idiosyncratic drug reaction • Illicit drug abuse

  9. Poisoning need not be drug • 46 歲的護衛員，連日來在東X房委會地盤通宵當值，飽受寒風吹襲，但他愛女情切，堅拒帶暖爐上班，自己則躲於一個約 30 平方呎大的「密室」內燒木取暖，結果因空氣不流通，缺氧身亡

  10. 蟾酥 • Dried extracts of secretion from mucous glands over toad’s skin • Contained digitalis-like compound • Digitalis overdose bradycardia, ventricular arrhythmia

  11. Poisoning need not be drug 毒鼠强 tetramine

  12. Poisoning need not be drug

  13. 鵝頭菇 Amanita phylloides

  14. Poisoning need not be suicide Dioxin

  15. Poisoning can be subtle • 82/F admit CMC ICU for septic shock • Coffee ground vomiting/ ARF on day 1 • High dose noradrenaline required • Short synacthen test 680 at start, 650 at one hour after • Deny chronic drug use • Closed question: took德國風痛靈for polyarthalgia for a few months

  16. 德國風痛靈丸 • TRL analysis • Menfenamic acid • Prednisolone • Pepcidine • Thiamine and B6 • Women suffered from exogenous steroid induced adrenal insufficiency

  17. What to know about toxicology • Chemical pathology • Toxicokinetics: • Toxicodyamics: mechanism of toxicity • Clinical toxicology • Epidemiology • Assessment: “poisoning history”, examination, toxic syndrome (Toxidrome) • Treatment: supportive, enhanced elimination, antidote, specific (Rarely)

  18. Poisoning with AED attendance • HKJEM 2005; 12(3): 156-161 • Multi-center prospective study • 6 AEDs over 6 month • 1467cases: 40% men; 32% 20-40 year-old • 64% suicidal attempt, 91% admitted • 24% sleeping pills DO, 18% analgesic DO • 1.4% death (CO poisoning contribute 1/2)

  19. DO as cause of hospital admission • In 2000, 118 admissions to PWH due to medicinal or non-medicinal poisoning • 34 patients un-intentional overdose: commonest cause is warfarin (85%) • 76 patients self-harm: commonest is panadol (41%) and sleeping pills (29%) • Two ICU and two CCU admissions • Nil death. Average LOS is 3.8 days

  20. Poisoning with in-patient care • JC of Chinese poison centers July/ 2005 • In 1994, 719 adults and 56 children admitted for acute poisoning • 1994-1998, 339 patients died of poisoning. Causes: therapeutics (34.8%); CO + LPG (21.5%); pesticides (16.2%); illicit drug (11.8%) and household products (6.5%) • Mortality: 4.8% at 1994  9.9% at 2002

  21. Poisoning with ICU admission • Consecutive adult patients admitted for acute poisoning from January 2000 to May 2008 • 7796 admissions, 265 poisoning cases (3.4%) • BDZ 25%; alcohol 23%; TCA 17%; CO 15%; household products 6.4% • 65.3% admitted due to altered mental state; 11% with rhabdomyolysis; 7.9% with CVS complication; 3.7% with ARF requiring CRRT • 3% hospital mortality Dr Grace SM Lam, PYNEH

  22. Indication for ICU admission • Unsecured airway • Cardiac support: shock/ arrhythmia • Status epilepticus • Risky/ sophisticated intervention for exposure to life-threatening poisoning e.g. dialysis; anti-venom for snake bite • Critical toxidrome e.g. NMS, Serotonin • Unknown cause for workup

  23. Clinical toxicology—history • Toxic substance related • What is the agent • What form and what route of exposure • When and How much • Any other people involved • Symptoms related • The symptoms and temporal sequence • Attempted self-treatment • PMH

  24. Clinical toxicology—examination • BP shock (Inderal) vs. hypertension (Ice) • Pulse brady (Digoxin) vs. tachy (Nuelin) • Temperature hypo (OHA) vs. fever (ASA) • RR hypo (Opioid) vs. hyper (CH3OH) • H’stix hypo (OHA) vs. hyper (CCB) • SaO2 desaturation (MetHb) vs. 100 (CO) • Neurological pupil, central, motor

  25. Examination  form toxidrome • Opioid: miosis; ileus, coma; apnea; • Symathomimetic: BP and HR; agitation • Anticholinergic: mydriasis; delirium; AROU • Cholinergic toxidrome: SLUDGE + kill “B” • Special syndromes Serotonin syndrome Neuroleptic malignant syndrome

  26. Specific treatment ICU is involved Antidote Decontamination Supportive care Exposure termination Management pyramid

  27. Intervention—ask yourself first • Is exposure confirmed? • Is substance potentially toxic? • Is toxicity potentially lethal? • Can we stop the absorption? • Can we enhance elimination? • Is there any effective antidote? • Is our intervention potentially kill? All procedures can kill

  28. Decontamination-Gastric lavage • Orogastric lavage with large-bore tube • With airway protected • Head down and lie lateral decubitus • Adequate volume until clear return • Best to be done within one hour • Drug with delayed gastric emptying: TCA/ narcotics/ carbamazepin • Never use in caustic injury and large FB

  29. Position statement on GL 2004 • American academy of clinical toxicology • “Gastric lavage should not be employed routinely. In experimental studies, the amount of marker removed was highly variable” • “Lack of beneficial effects in clinical studies” • “Serious risks of procedure include aspiration; laryngospasm; perforation ”

  30. Facts about activated charcoal • Toxins adsorbed to pores of charcoal • Optimum dose: 10 to 1 charcoal to drug ratio by weight. Unknown quantity of poison  dose depends on tolerability • Some agents are adsorbed poorly, including iron/ lithium and alcohols • Warning: coma/ poor gut mobility/ caustic substance

  31. How activated charcoal works

  32. Multi-dose activated charcoal (MDAC) • Abolish enterohepatic circulation • Enteroenteric removal e.g. aminophylline • Dose: 1mg/kg BW for 3 doses Q6 hours • NOT if caustics; in IO; drugs not bound • Aaminophylline (aspirin) Bbarbiturates Ccarbamazepine Ddigoxin; dapsone Qqunine

  33. Whole bowel irrigation • PEG via RT 1-2L/ hour • Until rectal output as clear as RT input • +/- erythromycin and maxolon • Indications • Toxin not bound by AC e.g. Li, Fe • Sustain release preparation • Bodypacker

  34. Delayed absorption kill suddenly A 51 year old man took a mixed overdose including 1.8–3.6 g of Herbesser SR, Panadol, aspirin, Isordil, and alcohol. Presented to hospital after six hours with mild hypotension and was treated with activated charcoal and IVF. Stayed at ‘O’ room. Eighteen hours after DO he had two generalised tonic-clonic seizures. The patient remained unresponsive with junctional bradycardia, unrecordable BP, and then developed asystolic. He was resuscitated with total 13.5 g IV calcium. He required inotropic support and temporary pacing over the next 48 hours. The case highlights the problems with delayed toxicity due to SR preparation when WBI was not delivered promptly Emerg Med J 2002; 19:355-357

  35. Compare decontaminations

  36. Enhanced elinimationalkaline diuresis • Increased alkali content in filtrate will favor dissociation of hydrogen ion from any weak acid • Ionized acid will not be reabsorbed, therefore being excreted in urine

  37. Alkaline diuresis application • CAMP: Chlorpropamide; Aspirin/ Methotrexate; Phenobarbitone • Aim at urine pH > 7.5 • Bolus: 1-2 mEq/ kg NaHCO3 • Infusion: 150 mEq NaHCO3 in 1L D5, rate at 2x normal maintenance (100-150ml/ hr) • Continuous K supplement • Stop if serum pH > 7.55 or APO

  38. Sleeping beauty • 32 yrs old • Good past health, came from Shanghai • Found dull-looking and sitting in street, with 2 empty bottles of 葡萄糖酸鈣片 • E1V1M5 in AED • Intubated • Admitted ICU

  39. Progress in ICU • Remained E1VTM1 without sedation • Bilateral pupils fixed and dilated, absent gag and cough reflexes, absent doll’s eye reflex • No limb/facial movement to painful stimuli, generalized hyporeflexia, absent plantar response • Urgent CT brain & MRI unremarkable • LP result not suggestive of CNS infection

  40. Serum toxicology result A/V on D5 Phenobarbitone level >1000 (non-toxic range: 43-172 μmol/L)

  41. ICU Treatment • Multiple dose activated charcoal • Activated charcoal 50gm q8h x 4doses • Stopped due to intestinal obstruction • Forced alkaline diuresis • 2LH20+300ml 8.4%NaHCO3 iv 100ml/hr • Charcoal haemoperfusion x 2 session • Complicated by thrombocytopenia • High flux intermittent haemodialysis x 4

  42. Progress • Pupils reactive on D7 • Gradual neurological recovery, E4VTM4 on D9 and extubated • Platelet count returned to normal • Full neurological recovery and transferred to medical ward on D11

  43. Haemoperfusion/haemodialysis • Most patients with phenobarbital overdose can be adequately treated with supportive care, cathartics, activated charcoal and forced alkaline diuresis. • In severely compromised patients, both haemodialysis and haemoperfusion have been used to enhance elimination of the drug. • Haemoperfusion is generally considered to be more effective because phenobarbital has significant protein binding.

  44. 2nd charcoal haemoperfusion 1st charcoal haemoperfusion 1st HD 2nd HD 3rd HD

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