clinical toxicology
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CLINICAL CLINICAL TOXICOLOGYTOXICOLOGY
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LEARNING OBJECTIVESLEARNING OBJECTIVES To understand the general principles of To understand the general principles of
clinical toxicologyclinical toxicology To know general factors that influence To know general factors that influence
toxicitytoxicity To understand the initial approach to the To understand the initial approach to the
poisoned patient in terms of setting poisoned patient in terms of setting immediate prioritiesimmediate priorities
To appreciate the necessity to conduct, as To appreciate the necessity to conduct, as the first order of business, those the first order of business, those procedures that evaluate and preserve procedures that evaluate and preserve vital signsvital signs
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LEARNING OBJECTIVESLEARNING OBJECTIVES To know what aspects of the physical To know what aspects of the physical
examination and what diagnostic tests are examination and what diagnostic tests are to be conducted to evaluate the general to be conducted to evaluate the general type as well as the specifics of the type as well as the specifics of the poisoningpoisoning
To understand the goals of treatment e.g. To understand the goals of treatment e.g. to treat the patient, not the poison, to treat the patient, not the poison, promptlypromptly
To know and understand strategies for To know and understand strategies for treatmenttreatment
To know and understand specific To know and understand specific approaches for reducing the body burden approaches for reducing the body burden of various poisonsof various poisons
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LEARNING OBJECTIVESLEARNING OBJECTIVES To know how to counteract toxicological To know how to counteract toxicological
effects at receptor sites, if possibleeffects at receptor sites, if possible To know and understand important To know and understand important
treatment contraindications that prevent treatment contraindications that prevent serious injury or death of patientsserious injury or death of patients
To be aware of newer approaches and To be aware of newer approaches and treatment modalitiestreatment modalities
To know where to rapidly obtain facts, To know where to rapidly obtain facts, specific antidotes, or other information on specific antidotes, or other information on poison control needed immediately to poison control needed immediately to treat the patienttreat the patient
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Common Causes of Death in the Common Causes of Death in the Acutely Poisoned PatientAcutely Poisoned Patient
Comatose patient:Comatose patient:– Loss of protective reflexesLoss of protective reflexes– Airway obstruction by flaccid tongueAirway obstruction by flaccid tongue– Aspiration of gastric contents into Aspiration of gastric contents into
tracheobronchial treetracheobronchial tree– Loss of respiratory driveLoss of respiratory drive– Respiratory arrestRespiratory arrest
Hypotension – due to depression of Hypotension – due to depression of cardiac contractilitycardiac contractility
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Common Causes of Death in the Common Causes of Death in the Acutely Poisoned PatientAcutely Poisoned Patient
Shock – due to hemorrhage or internal Shock – due to hemorrhage or internal bleedingbleeding
Hypovolemia – due to vomiting, diarrhea Hypovolemia – due to vomiting, diarrhea or vascular collapseor vascular collapse
Hypothermia – worsened by i.v. fluids Hypothermia – worsened by i.v. fluids administered rapidly at room temperatureadministered rapidly at room temperature
Cellular hypoxia – in spite of adequate Cellular hypoxia – in spite of adequate ventilation and Oventilation and O22 admin. – due to CN, CO admin. – due to CN, CO or Hor H22S poisoningS poisoning
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Common Causes of Death in the Common Causes of Death in the Acutely Poisoned PatientAcutely Poisoned Patient
Seizures – may result in pulmonary Seizures – may result in pulmonary aspiration;asphyxiaaspiration;asphyxia
Muscular hyperactivity resulting in Muscular hyperactivity resulting in hyperthermia, muscle breakdown, hyperthermia, muscle breakdown, myoglobinemia, renal failure, lactic myoglobinemia, renal failure, lactic acidosis and hyperkalemiaacidosis and hyperkalemia
Behavioral effects –traumatic injury Behavioral effects –traumatic injury ferom fights, accidents, fall from hih ferom fights, accidents, fall from hih places. Suicides, etcplaces. Suicides, etc
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Common Causes of Death in the Common Causes of Death in the Acutely Poisoned PatientAcutely Poisoned Patient
Massive damage to a specific organ Massive damage to a specific organ system:system:– Liver (acetaminophen; amanita Liver (acetaminophen; amanita
phylloides [poison mushroom]phylloides [poison mushroom]– Lungs (paraquat)Lungs (paraquat)– Brain (demoic acid)Brain (demoic acid)– Kidney (ethylene glycol)Kidney (ethylene glycol)– Heart (cobalt salts)Heart (cobalt salts)
Note: death may occur in 48 – 72 hrsNote: death may occur in 48 – 72 hrs
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APPROACH TO THE POISONED APPROACH TO THE POISONED PATIENTPATIENT
History; Oral statements concerning History; Oral statements concerning details details
Call Poison Control Center re: drug Call Poison Control Center re: drug labeling labeling
Initial physical examinationInitial physical examination Assessment of vital signs Assessment of vital signs Eye examination Eye examination CNS and mental status examinationCNS and mental status examination
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APPROACH TO THE POISONED APPROACH TO THE POISONED PATIENTPATIENT
Examination of the skin Examination of the skin Mouth examination Mouth examination Lab (clinical chemistry and x-ray Lab (clinical chemistry and x-ray
procedures procedures Renal function tests Renal function tests EKG EKG Other screening testsOther screening tests
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TREATMENT OF ACUTE TREATMENT OF ACUTE POISONINGPOISONING
Treat the patient, not the poison", Treat the patient, not the poison", promptlypromptly
Supportive therapy essential Supportive therapy essential Maintain respiration and circulation – Maintain respiration and circulation –
primaryprimary
Judge progress of intoxication by: Judge progress of intoxication by: Measuring and charting vital signs and Measuring and charting vital signs and
reflexes reflexes
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TREATMENT OF ACUTE TREATMENT OF ACUTE POISONINGPOISONING
- 1st Goal - keep concentration of - 1st Goal - keep concentration of poison as low as possible by poison as low as possible by preventing absorption and increasing preventing absorption and increasing elimination elimination
- 2nd Goal - counteract toxicological - 2nd Goal - counteract toxicological effects at effector site, if possible effects at effector site, if possible
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PREVENTION OF ABSORPTION PREVENTION OF ABSORPTION OF POISONOF POISON
Decontamination from skin surfaceDecontamination from skin surface Emesis: indicated after oral ingestion of Emesis: indicated after oral ingestion of
most chemicals; most chemicals; – must consider time since chemical ingestedmust consider time since chemical ingested
Contraindications:Contraindications: ingestion of corrosives such as strong acid or alkali; ingestion of corrosives such as strong acid or alkali; if patient is comatose or delirious; if patient is comatose or delirious; if patient has ingested a CNS stimulant or is if patient has ingested a CNS stimulant or is
convulsing; convulsing; if patient has ingested a petroleum distillate if patient has ingested a petroleum distillate
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PREVENTION OF ABSORPTION PREVENTION OF ABSORPTION OF POISONOF POISON
Induce emesis in the following Induce emesis in the following ways: ways:
mechanically by stroking posterior mechanically by stroking posterior pharynx; pharynx;
use of syrup of ipecac, 1 oz followed by use of syrup of ipecac, 1 oz followed by one glass of water; one glass of water;
use of apomorphine parenterallyuse of apomorphine parenterally
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PREVENTION OF ABSORPTION PREVENTION OF ABSORPTION OF POISONOF POISON
Gastric lavage: insert tube into Gastric lavage: insert tube into stomach and wash stomach with stomach and wash stomach with water or ½ normal saline to remove water or ½ normal saline to remove unabsorbed poisonunabsorbed poison
Contraindications are the same as Contraindications are the same as for emesis except that the for emesis except that the procedure should not be attempted procedure should not be attempted with young childrenwith young children
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PREVENTION OF ABSORPTION PREVENTION OF ABSORPTION OF POISONOF POISON
Chemical Adsorption Chemical Adsorption activated charcoal will adsorb many activated charcoal will adsorb many
poisons thus preventing their absorptionpoisons thus preventing their absorption
do not use simultaneously with ipecac if do not use simultaneously with ipecac if
poison is excreted into bile in active formpoison is excreted into bile in active form
adsorbent in intestines may interrupt adsorbent in intestines may interrupt
enterohepatic circulationenterohepatic circulation
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PREVENTION OF ABSORPTION PREVENTION OF ABSORPTION OF POISONOF POISON
Purgation Purgation Used for ingestion of enteric coated tablets Used for ingestion of enteric coated tablets
when time after ingestion is longer than when time after ingestion is longer than one hour one hour
Use saline cathartics such as sodium or Use saline cathartics such as sodium or magnesium sulfatemagnesium sulfate
Chemical InactivationChemical Inactivation Not generally done, particularly for acids or Not generally done, particularly for acids or
bases or inhalation exposure bases or inhalation exposure For ocular and dermal exposure as well as For ocular and dermal exposure as well as
burns on skin; treat with copious water burns on skin; treat with copious water
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PREVENTION OF ABSORPTION PREVENTION OF ABSORPTION OF POISONOF POISON
Alteration of biotransformation Alteration of biotransformation Interfere with metabolic conversion of Interfere with metabolic conversion of
compound to toxic metabolite compound to toxic metabolite Metabolism of some compounds Metabolism of some compounds
produces highly reactive electrophilic produces highly reactive electrophilic intermediates; if nucleophiles present, intermediates; if nucleophiles present, toxicity is minimal; if nucleophiles toxicity is minimal; if nucleophiles depleted, toxicity results depleted, toxicity results
Increasing urinary excretion by Increasing urinary excretion by acidification or alkalinization acidification or alkalinization
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PREVENTION OF ABSORPTION PREVENTION OF ABSORPTION OF POISONOF POISON
Decreasing passive resorption from Decreasing passive resorption from nephron lumennephron lumen
DiuresisDiuresis CatharticsCathartics Peritoneal dialysis Peritoneal dialysis Hemodialysis Hemodialysis Hemoperfusion Hemoperfusion
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Antagonism of the absorbed poison Antagonism of the absorbed poison
If poisoning is due to agonist acting If poisoning is due to agonist acting at receptors for which specific at receptors for which specific antagonist is available; antagonist antagonist is available; antagonist may be available may be available
Drugs that stimulate antagonistic Drugs that stimulate antagonistic physiologic mechanisms may of little physiologic mechanisms may of little clinical value; titration difficult clinical value; titration difficult
Use of antibodiesUse of antibodies
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Strategies for Treatment of the Strategies for Treatment of the Poisoned PatientPoisoned Patient
Evaluate and stabilize vital signsEvaluate and stabilize vital signs Give supportive therapy, if neededGive supportive therapy, if needed Determine the type and specifics of Determine the type and specifics of
the poisonthe poison Time of exposureTime of exposure Determine the presumed current Determine the presumed current
location of the poisonlocation of the poison Determine Volume of Distribution Determine Volume of Distribution
and Kand Ki i for the poisonfor the poison
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Strategies for Treatment of the Strategies for Treatment of the Poisoned PatientPoisoned Patient
Use the drug dissociation constant, Use the drug dissociation constant, presumed pH based on location and the presumed pH based on location and the Henderson-Hasselbach equation to Henderson-Hasselbach equation to determine the ratio of ionized to non-determine the ratio of ionized to non-ionized poisonionized poison
Determine the immediate (real time) risk Determine the immediate (real time) risk or hazard for absorptionor hazard for absorption
Intiate body burden reduction procedures Intiate body burden reduction procedures or specific antidotes based on the above or specific antidotes based on the above informationinformation
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Strategies for Treatment of the Strategies for Treatment of the Poisoned PatientPoisoned Patient
If volume of distribution is very large; do If volume of distribution is very large; do not waste time on any type of dialysisnot waste time on any type of dialysis
X-ray for location of enteric coated pills X-ray for location of enteric coated pills and use cathartics if in the stomachand use cathartics if in the stomach
Use hypocholesteremics for poisons Use hypocholesteremics for poisons trapped in enterohepatic biliary systemtrapped in enterohepatic biliary system
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SPECIFIC ANTIDOTESSPECIFIC ANTIDOTESPoisonPoison
AcetaminophenAcetaminophenAcetylcholinesterases, Acetylcholinesterases,
OP’s, physostigmineOP’s, physostigmineIron saltsIron salts
Methanol, Ethylene Methanol, Ethylene glycolglycol
Mercury, leadMercury, leadNarcotic drugsNarcotic drugs
Anti/muscarinics-Anti/muscarinics-cholinergicscholinergics
OP anticholinergicsOP anticholinergics
AntidoteAntidoteAcetylcysteineAcetylcysteine
AtropineAtropine
DeferoximeDeferoximeEthanolEthanol
Metal ChelatorsMetal ChelatorsNaloxoneNaloxone
PhysostigminePhysostigminePraladoxime (2-PAM)Praladoxime (2-PAM)
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