History and Physical Examination 11 History and Physical Examination Accurate identification of ingestants is particularly important in the patient exposed to agents that have delayed onset of toxic effects, such as acetonitrile, which is metabolized to cyanide, or MAOIs.

Physical Examination The physical examination gives important clues to both the severity and the cause of poisoning. Examples include the respiratory depression of barbiturate or opioid poisoning and the tachycardia and hypertension of poisoning with sympathomimetic agents.

Decontamination The decision to evacuate the GIT or administer activated charcoal should be based on: the type of ingestion estimated quantity size of pill or tablet time since ingestion concurrent ingestions age and size of the patient.

PREVENTION OF ABSORPTION OF POISON Induce emesis in the following ways: mechanically by stroking posterior pharynx; use of syrup of ipecac, 15ml for children and 30ml for adults followed by one glass of water; use of apomorphine parenterally

PREVENTION OF ABSORPTION OF POISON Inducing emesis by Syrup of ipecac is used rarely in the prehospital setting, and virtually never in hospitals. Limited indications for the use of orogastric lavage, nasogastric suction, and whole-bowel irrigation exist.

PREVENTION OF ABSORPTION OF POISON Chemical Adsorption activated charcoal will adsorb many poisons thus preventing their absorption, it used within 1 hour of ingestion. adsorbent in intestines may interrupt enterohepatic circulation.

PREVENTION OF ABSORPTION OF POISON 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 The use of cathartics has never been shown to alter clinical outcome. However, their inappropriate use has been associated with significant morbidity and mortality, and their routine use is no longer recommended.

PREVENTION OF ABSORPTION OF POISON 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

Dermal decontamination is best accomplished with large amounts of water. However, the use of water on skin contaminated with metallic sodium, metallic potassium, or phosphorus (white, yellow) may result in further skin injury owing to heat generation and explosive injury. Irrigation of phenol burns with low molecular weight polyethylene glycol is effective.

Other therapies, such as topical calcium salts for hydrofluoric acid burns, may be indicated following initial water decontamination. Ocular decontamination can be accomplished with water or normal saline irrigation.

Diagnostic Testing serum electrolytes calculated anion gap glucose arterial blood gases serum creatinine liver function tests Electrocardiograms (ECG): cardiac dysrhythmias or conduction delays Routine radiographs: pulmonary injury

Antidotes

Antidotes

Antidotes Digoxin Digoxin-specific antibody fragments (Fab) Digitalis Other cardiac glycosides, e.g., bufodienalides (Bufo toads) Oleander Dimercaprol Arsenic Lead Mercury Ethanol Diethylene glycol Ethylene glycol Methanol Experimental: sodium monofluoroacetate Flumazenil Benzodiazepines Venlafaxine

Antidotes Folic acid/tetrahydrofolic acid (leucovorin) Methanol Methotrexate Fomepizole Ethylene glycol Glucagon Beta-adrenergic receptor antagonists Calcium channel antagonists Hyberbaric oxygen Carbon monoxide Experimental: carbon tetrachloride Cyanide, hydrogen sulfide Methylene blue Methemoglobin-producing agents

Antidotes N-Acetylcysteine Acetaminophen Experimental: carbon tetrachloride, chloroform, pennyroyal oil Naloxone, nalmefene, naltrexone Opioids Physostigmine Anticholinergic agents, e.g., diphenhydramine, Jimsonweed (Datura spp.), scopalamine Pralidoxime Organophosphates Protamine Heparin Pyridoxine Isoniazid Monomethylhydrazine mushrooms (Gyrometra esculenta)

Antidotes Sodium bicarbonate Myocardial sodium channel blockers, e.g., cyclic antidepressants, cocaine, norpropoxyphene, class Ia and Ic antidysrhythmics, piperidine phenothiazines (thioridazine, mesoridazine) Altered tissue distribution/enhanced elimination: chlorophenoxy herbicides, chlorpropamide, formic acid (methanol), methotrexate, phenobarbital, salicylates Neutralization: inhaled chlorine gas, hydrogen chloride, phosgene Succimer Arsenic Lead Mercury Vitamin K Anticoagulants, e.g., warfarin, long-acting anticoagulant rodenticides

Increase Elimination Of Toxic Agents Increasing urinary excretion by acidification or alkalinization Decreasing passive resorption from nephron lumen Diuresis Cathartics Peritoneal dialysis Hemodialysis Hemoperfusion

Forced diuresis and pH alteration It is useful when compounds or active metabolites are eliminated by the kidney and diuresis enhances their excretion. Mannitol and furosemide are generally used. This method is no longer indicated because it increase the excretion of chemical only two fold. Alkaline diuresis is achieved by administration of sodium bicarbonate, 1-2 mEq/kg every 3-4 hr.

The potential uses of urine alkalinization have been with weak acid such as salicylates and phenobarbital. Acid diuresis is possible by using ammonium chloride, 75mg/kg/24hr. Acid diuresis increase the elimination of weak bases, such as amphetamine, phencyclidine, and quinidine. This procedure is no longer recommended.

Dialysis and hemoperfusion Peritoneal Dialysis The procedure is undertaken by inserting a tube through a small incision made in the abdominal area into the peritoneum. The peritoneal membrane serves as the semipermeable (dialyzing) membrane. The dialyzable chemical diffuses from blood across the peritoneal membrane into the dialyzing fluid (from higher concentration to lower concentration).

Peritoneal Dialysis Advantages:- Easy. Lowest risk for complications. Disadvantages:- The least effective method for removing most poisons. It is 5-10 time less efficient than hemodialysis. Not suitable when rapid removal of a toxic substance is needed. Complications include:- abdominal pain, intraperitoneal bleeding, intestinal, bladder, liver, or spleen perforation; peritonitis; water and electrolyte imbalance; and protein loss.

Procedure for peritoneal dialysis

Hemodialysis Two catheters are inserted into the patient’s femoral vein. Blood is pumped from one catheter through the dialysis unit, across the semipermeable membrane, and back through the other catheter. The procedure is continued for 6-8 hr. the solubilized chemical diffuses across the semipermeable membrane into the dialysis solution. Clearance of the toxic agent is based on differences in osmotic and concentration gradients.

Procedure for hemodialysis

Procedure for hemodialysis

Disadvantages The chemical that removed by this way must have a low molecular size. Less effective for drug that are highly protein-bound. Useless for chemicals that are extensively taken by the tissues. Complications include clotting, and seepage of blood from around connections, hypotension, convulsions, arrhythmias, infection, and hematologic defects.

Hemoperfusion The passage of blood through columns of adsorptive material, such as activated charcoal, to remove toxic substances from the blood. It is more effective than peritoneal dialysis and hemodialysis for removing compound that are: Lipid soluble. Protein bound. Poorly dialyzable. Complications include:- trapping of white blood cells and platelets and microembolization. Newer systems solved this problem.

Procedure for hemoperfusion

Pediatric poisoning Approximately 54% of childhood exposures are to xenobiotics that are commonly found around the house, such as cleaning products, cosmetics, plants, hydrocarbons, and insecticides; approximately 46% are to pharmaceuticals. In older children and adolescents, approximately 49% of exposures are to non-pharmaceutical xenobiotics, and approximately 51% are to pharmaceuticals.

Who is more prone to toxicity? Children less than 5 years old. Why?

The environment: includes the area around the home. Children are curious and investigative. Many household products are marked in attractive packages.

4. The natural tendency of children to place everything into their mouth.

5. Taking medication in the presence of children “If I see it, I can do it,” 6. Dosing errors 7. Poisons are often left in easy view and accessible. Poisoning also occur because many products are used in unvented areas. Another factor that increase toxicity is the absence of information about the constituents of many products.

The leading causes of reported exposures in children and adolescents

The leading causes of reported exposures in children and adolescents