Clinical Toxicology Lecture Notes PDF

# CLINICAL TOXICOLOGY - **Fifth stage** 2024-2025 - **Lecturer** Salim Dawood - **Lec.1+2** ## Learning Objectives - To understand the general principles of clinical toxicology - To know general factors that influence toxicity - To understand the initial approach to the poisoned patient in terms...

# CLINICAL TOXICOLOGY - **Fifth stage** 2024-2025 - **Lecturer** Salim Dawood - **Lec.1+2** ## Learning Objectives - To understand the general principles of clinical toxicology - To know general factors that influence toxicity - To understand the initial approach to the poisoned patient in terms of setting immediate priorities. - To appreciate the necessity to conduct, as the first order of business, those procedures that evaluate and preserve vital signs - To know what aspects of the physical examination and what diagnostic are to be conducted to evaluate the general type as well as the specifics of the poisoning. - To understand the goals of treatment e.g. to treat the patient, not the poison, promptly. - To know and understand strategies for treatment. - To know and understand specific approaches for reducing the body burden of various poisons. - To know how to counteract toxicological effects at receptor sites, if possible. - To know and understand important treatment contraindications that prevent serious injury or death of patients. - To be aware of newer approaches and treatment modalities - To know where to rapidly obtain facts, specific antidotes, or other information on poison control needed immediately to treat the patient. ## Common Causes of Death in the Acutely Poisoned Patient - **Comatose patient:** - Loss of protective reflexes - Airway obstruction by flaccid tongue - Aspiration of gastric contents into tracheobronchial tree - Loss of respiratory drive - Respiratory arrest - **Hypotension - due to depression of cardiac contractility** - **Shock - due to hemorrhage or internal bleeding** - **Hypovolemia - due to vomiting, diarrhea or vascular collapse** - **Hypothermia - worsened by i.v. fluids administered rapidly at room temperature** - **Cellular hypoxia - in spite of adequate ventilation and O₂ admin. - due to CN, CO or H₂S poisoning** ## Approach to the Poisoned Patient - History; Oral statements concerning details - Call Poison Control Center re: drug labeling - Initial physical examination - Assessment of vital signs - Eye examination - CNS and mental status examination - Examination of the skin - Mouth examination - Lab (clinical chemistry and x-ray procedures - Renal function tests - EKG - Other screening tests ## Treatment Of Acute Poisoning - Treat the patient, not the poison", promptly - Supportive therapy essential - Maintain respiration and circulation - primary - Judge progress of intoxication by: - Measuring and charting vital signs and reflexes - 1st Goal - keep concentration of poison as low as possible by preventing absorption and increasing elimination - 2nd Goal - counteract toxicological effects at effector site, if possible ## Prevention of Absorption of Poison - Decontamination from skin surface - Emesis: indicated after oral ingestion of most chemicals; - must consider time since chemical ingested - Contraindications: - ingestion of corrosives such as strong acid or alkali; - if patient is comatose or delirious; - if patient has ingested a CNS stimulant or is convulsing; - if patient has ingested a petroleum distillate - Induce emesis in the following ways: - mechanically by stroking posterior pharynx; - use of syrup of ipecac, 1 oz followed by one glass of water; - use of apomorphine parenterally - Gastric lavage: insert tube into stomach and wash stomach with water or 1/2 normal saline to remove unabsorbed poison - Contraindications are the same as for emesis except that the procedure should not be attempted with young children - Chemical Adsorption - activated charcoal will adsorb many poisons thus preventing their absorption - do not use simultaneously with ipecac if poison is excreted into bile in active form - adsorbent in intestines may interrupt enterohepatic circulation - Use saline cathartics such as sodium or magnesium sulfate - Purgation - Used for ingestion of enteric coated tablets when time after ingestion is longer than one hour - Use saline cathartics such as sodium or magnesium sulfate - Chemical Inactivation - Not generally done, particularly for acids or bases or inhalation exposure - For ocular and dermal exposure as well as burns on skin; treat with copious water - Alteration of biotransformation - Interfere with metabolic conversion of compound to toxic metabolite - Metabolism of some compounds produces highly reactive electrophilic intermediates; if nucleophiles present, toxicity is minimal; if nucleophiles depleted, toxicity results - Increasing urinary excretion by acidification or alkalinization - Decreasing passive resorption from nephron lumen - Diuresis - Cathartics - Peritoneal dialysis - Hemodialysis - Hemoperfusion ## Strategies for Treatment of the Poisoned Patient - Evaluate and stabilize vital signs - Give supportive therapy, if needed - Determine the type and specifics of the poison - Time of exposure - Determine the presumed current location of the poison - Determine Volume of Distribution and Ki for the poison