GI Decontamination Gastric Lavage Adverse Effects

Poisonings’ treatment Therapeutic Approach to the Poisoned Veterinary Patient Emergency Therapy: Keep the Patient Alive ◼ Emergency Stabilization ◼ • Correct life-threatening conditions. ◼ • Use the ABCs of emergency medicine. ◼ • After attending to the ABCs, move to D, decontamination. ABCs of Emergency Triage AIRWAY ◼ • Is the airway patent? ◼ • Does the animal have a gag reflex? ◼ • Is intubation necessary? BREATHING ◼ • Is the animal breathing spontaneously? ◼ • What colour are the mucous membranes? CIRCULATION ◼ • Pulse rate ◼ • Blood pressure ◼ • Insert venous catheter ◼ • Electrocardiogram (depending upon clinical presentation) ◼ • Treat arrhythmias Supportive Care ◼ FLUID THERAPY ◼ • Intravenous access may be necessary for administration of antidote. ◼ • Protracted vomiting or diarrhea may dehydrate a poisoned patient. ◼ • Normal saline solution or lactated Ringer solution is a good choice ❑ for initial fluid therapy. ◼ • Often fluid volume is more important than fluid composition. ◼ • Diuresis may be needed for increased elimination or to prevent ❑ renal failure. Supportive Care ◼ SEIZURE CONTROL ◼ • Not a common presentation in large animals. ◼ • Diazepam is a good first-choice therapeutic agent. ❑ • small animal: 0.5 mg/kg IV, 1.0 mg/kg rectally ❑ • cattle: 0.5–1.5 mg/kg IV ❑ • horses (adult): 25–50 mg IV ◼ • Phenobarbital ❑ • small animals: 5–20 mg/kg IV to effect ◼ • Pentobarbital ❑ • small animals: 5–15 mg/kg IV to effect ❑ • cattle: 1–2 g IV Supportive Care ◼ MAINTENANCE OF BODY TEMPERATURE ◼ • Hypothermic patient ❑ • warmed fluids ❑ • warm water recirculating pads ❑ • blankets ❑ • close monitoring of circulatory status during rewarming ◼ • Hyperthermic patient ◼ • Initiate evaporative cooling. ❑ Dampen the fur. ❑ Place fans close to the patient. Supportive Care ◼ MAINTENANCE OF BODY TEMPERATURE ◼ • Hyperthermic patient ◼ • Immerse patient in a bathtub if necessary. ◼ • Spray large animals with water from a hose and place them in a shaded enclosure. ◼ • Control seizures, if present. ❑ Reduce heat generated by muscular activity. ◼ • Control shivering. ❑ Do not use chlorpromazine (may lower seizure threshold). ❑ Diazepam may reduce shivering. Decontamination ◼ • Decontamination is the process of removing a toxin from an animal. ◼ • The primary goal of decontamination is to prevent additional toxin exposure. ◼ • Most veterinary intoxications occur through the dermal or oral route. Decontamination ◼ Ocular Decontamination ◼ • If the animal had an ocular exposure to a toxin or irritant, ocular decontamination may be warranted. ◼ • Flush the affected eye with copious volumes of sterile saline solution or water. ◼ • Flush for 10–15 minutes. Decontamination ◼ Ocular Decontamination ◼ • Do not attempt to use fluids (acid or alkaline) to neutralize the toxin. ◼ • Evaluate the cornea and adnexa after complete irrigation. ◼ • Ocular exposure to alkaline substances may require immediate ophthalmic care. Decontamination ◼ Dermal Decontamination ◼ • Animals often are exposed to poisons (pesticides) by the dermal route and may need decontamination to reduce further exposure. ◼ • The hair or fur can serve as a reservoir for continued absorption of a toxin. ◼ • It is critical that the persons performing dermal decontamination be protected from exposure to the toxin during the procedure. ◼ • Wear rubber gloves and a raincoat. Decontamination ◼ Dermal Decontamination ◼ • Wash the animal with a mild shampoo (not insecticidal) or dish soap. ◼ • Rinse completely. ◼ • Repeat the procedure until all traces of odour are removed from the animal. ◼ • A mildly alkaline dip (sodium bicarbonate) may promote hydrolysis of some insecticides. ◼ • Observe animal for any signs of hypothermia or seizure activity. ◼ • Use high-pressure spraying of groups of animals if herd exposure has occurred. Decontamination ◼ GI Decontamination ◼ • Usually comprises the following steps: ❑ • emesis or emetic therapy ❑ • possibly gastric lavage ❑ • whole bowel irrigation ❑ • activated charcoal therapy ❑ • cathartic therapy ❑ • enterotomy or rumenotomy in special cases ◼ • An area of debate among toxicologists who treat humans ◼ • Common in veterinary medicine Decontamination ◼ GI Decontamination ◼ • In veterinary medicine, the patient population does not attempt suicide. ◼ • Intoxications are real, not an attempt to gain attention. ◼ • Many intoxicated veterinary patients benefit from GI decontamination. ◼ • The use of activated charcoal is generally safe and accepted by both veterinary and human toxicologists. GI Decontamination ◼ Emetic Therapy - General ◼ • Emesis is more effective early in intoxication. ◼ • Can be extremely beneficial if induced within minutes of ingestion of toxin. ◼ • May be induced by the owner at home. ◼ • Outer limit of effectiveness is 3–4 hours after ingestion. ❑ varies with toxin ingested and physiologic condition of the animal GI Decontamination ◼ Emetic Therapy – General ◼ • Emetic therapy is useful after ingestion of toxins that are not adsorbed by charcoal. ❑ • example: ethylene glycol, iron ◼ • Emetic therapy should not delay administration of activated charcoal or antidote therapy. GI Decontamination Emetic Agents Not Recommended for Veterinary Patients ◼ COPPER SULFATE ❑ • Ineffective emesis ❑ • Risk of copper intoxication ◼ TABLE SALT ❑ • Ineffective emesis ❑ • Risk of hypernatremia ◼ DRY MUSTARD ❑ • Ineffective emesis ◼ DIRECT DIGITAL PHARYNGEAL STIMULATION ❑ • Ineffective emesis ❑ • Danger to the owner, veterinarian, or technician GI Decontamination Locally Acting Emetic Agents HYDROGEN PEROXIDE (3%) ◼ • Indications ❑ • induction of emesis ❑ • removal of toxin ◼ • General ❑ • Use only 3% hydrogen peroxide (not the hair-bleaching formulation, which is 30%). ❑ • Not reliable enough for use in the clinic — generally administered by the owner. GI Decontamination Locally Acting Emetic Agents HYDROGEN PEROXIDE (3%) ◼ • Mechanism of action ❑ • Direct irritation and stimulation of the mucosa of the pharynx and esophagus ◼ • Contraindications ❑ • same as general contraindications to emesis ◼ • Therapeutic dose ❑ • dogs and cats: 5–25 mL/4.5-5 kg by mouth ❑ • dose may be repeated in 5–10 minutes ◼ • Adverse effects ❑ • ineffective or inconsistent emesis that can delay charcoal therapy GI Decontamination Locally Acting Emetic Agents SYRUP OF IPECAC ◼ • General ❑ • locally and centrally acting emetic agent ❑ • mixture of plant-derived alkaloids ◼ emetine ◼ cephaeline ❑ • supplied as a syrup in 15-mL or 30-mL bottles in all pharmacies ❑ • long-term use by humans, as by persons with bulimia, can cause cardiomyopathy and arrhythmia GI Decontamination Locally Acting Emetic Agents SYRUP OF IPECAC ◼ • Mechanism of action ❑ • locally acting emetic action ◼ direct irritation of the gastric mucosa ❑ • centrally acting emetic action ◼ direct stimulation of the chemoreceptor trigger zone ❑ • emesis generally occurs within 30 minutes ◼ • Indications ❑ • induction of emesis in dogs ❑ • use at home by owners ❑ • not commonly used in veterinary clinics GI Decontamination Locally Acting Emetic Agents SYRUP OF IPECAC ◼ • Contraindications ❑ • same as general contraindications to emesis ❑ • cats may be more sensitive to the possible cardiotoxic effects ◼ • Therapeutic dose ❑ • dogs: 1–2 mL/kg by mouth ◼ some sources suggest not exceeding a 15-mL total dose ◼ follow immediately with 5 mL/kg water ❑ • cats: 5–10 mL by mouth ◼ may have to dilute (50:50) with water ◼ may require use of gastric or nasogastric tube GI Decontamination Locally Acting Emetic Agents SYRUP OF IPECAC ◼ • Contraindications ❑ • same as general contraindications to emesis ❑ • cats may be more sensitive to the possible cardiotoxic effects ◼ • Therapeutic dose ❑ • dogs: 1–2 mL/kg by mouth ◼ some sources suggest not exceeding a 15-mL total dose ◼ follow immediately with 5 mL/kg water ❑ • cats: 5–10 mL by mouth ◼ may have to dilute (50:50) with water ◼ may require use of gastric or nasogastric tube GI Decontamination Locally Acting Emetic Agents SYRUP OF IPECAC ◼ • slower than apomorphine ◼ • less reliable—may delay the onset of charcoal therapy ◼ • Adverse effects ❑ • CNS depression GI Decontamination Centrally Acting Emetic Agents APOMORPHINE ◼ • General ❑ • Apomorphine is a derivative of morphine. ◼ has minimal analgesic properties ◼ has marked emetic activity ❑ • no longer used in human medicine because it causes respiratory depression ❑ • unstable in light and air ◼ becomes discolored ◼ Greenish color indicates partial decomposition. GI Decontamination Centrally Acting Emetic Agents APOMORPHINE ◼ • Availability of apomorphine ❑ • often difficult to obtain ❑ • Consult local pharmacist for assistance. ❑ • Compounding pharmacist may be needed to produce a specific formulation. ◼ • Mechanism of action ❑ • stimulation of dopamine receptors in the chemoreceptor trigger zone ❑ • stimulation, which causes emesis, followed by inhibition GI Decontamination Centrally Acting Emetic Agents APOMORPHINE ◼ • Indications ❑ • emetic agent for dogs ◼ • Contraindications ❑ • same as general contraindications to emesis ❑ • controversial in treatment of cats GI Decontamination Centrally Acting Emetic Agents APOMORPHINE ◼ • Therapeutic dose ◼ • must be made fresh ❑ grind up a tablet and dissolve in water ❑ pass through filter to sterilize before intravenous administration ❑ crush tablets and instill in conjunctival sac GI Decontamination Centrally Acting Emetic Agents APOMORPHINE ◼ • Therapeutic dose ◼ • 0.03 mg/kg IV - immediate (<1 min) onset of emesis ◼ • 0.04–0.08 mg/kg IM or SC - emesis within

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