General Principles of Management of Toxicoses Flashcards
Tox
What are some typical scenarios in which an animal is suspected for toxicosis?
i. The animal has been exposed to a known
toxicant
ii. The animal has been exposed to an unknown
substance that may be a toxicant
iii. The animal displays signs of disease of an
undetermined cause for which toxicosis must be
considered as part of the differential diagnosis
How do you approach making a diagnosis when you suspect toxicosis?
- Obtain a complete history
- time of onset of clinical signs and linking to particular toxicant
- treat life-threteaning problems
- description of home environment
- information about toxic agent
- was animal indoors, outdoors? when toxicosis occured. MUST remove from environment to prevent re-exposure/exposure to others.
- Trade name of product/medication, active and inactive ingredients, ingredient concentrations, contact information from packaging if available. - Perform a complete physical examination
- Perform an exposure assessment: dose-response assessment and exposure assessment calculations
- Consider clinical signs and clinical pathologic findings
- Sample collection and toxicology testing
– Hold toxicologic samples until the results of other tests (e.g., clinical pathology, histopathology, and bacteriology) are
available to allow for focused toxicologic testing - If needed, Postmortem examination and sampling
- Occasionally a bioassay may be done
What condition should gastric contents and fecal material be stored in? This sample is considered?
frozen
Diagnostically useful
What condition should urine be stored in? This sample is considered?
frozen
Diagnostically useful
What condition should serum be stored in? This sample is considered?
separated from clot promptly and frozen
Diagnostically useful
What condition should blood be stored in?
Refrigerated
What condition should liver be stored in?
frozen
What condition should kidney be stored in?
frozen
What condition should brain be stored in?
Frozen
What condition should lung be stored in?
frozen
What condition should food and source material be stored in?
Dry material should be kept dry at room temp. moist material should be frozen
What condition should water be stored in?
refrigerated
CSF and tissue samples may also be useful for diagnostic purposes.
What are ABC’s of emergency care?
- A = Airway: Check for airway patency/obstruction. Most common factors contributing ot death from poisoning is loss of airway protective reflexes with subsequent airway obstruction caused by flaccid tongue, permanent aspiration of gratric contents, or respiratory arrest.
- B = Breathing: Check for signs of ineffective
breathing, e.g., apnea, stertor = high pased breathing sound caused by disrupted airflow due to obstruction in pharynx or trachea, stridor = noise from vibration of pharyngeal tissues due to significant UR obstruction and subsequent turbulent airflow downstream in upper airway, hyperpnea, hypopnea, agonal breathing (gasping) - C = Circulation: Assess mucous membrane color, capillary refill time, heart rate, pulse quality & rhythm, and peripheral temperature
How do you triage a patient when you suspect them for toxicoses?
- Triage: involves a quick evaluation of four major
organ systems to determine whether the patient
can be categorized as stable or unstable = experiencing life threatening signs and requires quick judgement and timely action. Should take less than 5 minutes.
– Cardiovascular: heart rate, mucous membrane color, capillary refill time, pulse quality & rhythm
– Respiratory: airway patency, respiration rate
– Central nervous system: gait, level of consciousness, pupil size, and position - Levels of consciousness are: alert = normal, depressed = quiet, unwilling to perform normal function but responds to env stimuli, obtunded = minimally responsive to auditory or tactile stimuli, stuporous = unresponsive to environmental stimuli but responds to painful stimuli or comatose = not responding to environmental or painful stimuli
– Renal: assessed by abdominal palpation for renal obstruction, other emergencies of renal are identified while assessing cardiovascular status
– Obtain an abbreviated history
How do you medically manage a patient suffering from toxicsosis?
- Control seizures, muscle tremors
– Diazepam, pentobarbital, methocarbamol - Control exsanguinating hemorrhage
- Assess metabolic derangements
– Correcting Acid-base and electrolyte imbalances → which can cause acidosis or alkalosis - Perform decontamination
- Provide supportive and symptomatic care
- Antidote therapy if antidote is available
What is decontamination?
Important step in treating toxicosis
* Decontamination may be required for oral,
inhalation, dermal, and ocular exposures
* The goal of decontamination is to minimize
exposure to potentially toxic substances
– Prevents or minimizes absorption
– Enhances elimination
* While performing decontamination, Wear personal protective equipment (PPE)
– Gloves, apron or other water-resistant clothing, and eye protection
What is oral decontamination?
Induction of Vomiting (Emesis)
* Removes potentially harmful substances from the
stomach
– Most useful within 30-90 min of the ingestion
* Emesis contraindications
– Weakened or severely ill patients
– Ingestions of caustic substances or hydrocarbons b/c folllowing ingestion of thse could aspirate into respiraotyr tract if vomiting occurs.
– Patients with altered level of consciousness (hyperactivity or depression/coma)
– Ingestions that took place a long time ago
– Unknown toxicant
– Animals that do not vomit
What are emetics used in dogs?
– Hydrogen peroxide (3%)
– Apomorphine
What are emetics used in cats?
– Xylazine
– Dexmedetomidine
– Midazolam/hydromorphone
What is not recommended to use as an emetic?
Not recommended: liquid dishwashing detergent,
powdered mustard = GI irritation, syrup of ipecac, salt = animal at risk for sodium ion toxicosis
How does water act as a diluent?
Water: works by diluting and making ingested
compounds less irritating
How does milk and liquid antacids act as diluents?
Milk and liquid antacids: sooth and coat damaged
mucous membrane surfaces
Why do you have to limit the amount of diluent given to a patient?
Reduces the risk of excessive distention of the
stomach leading to vomiting and aspiration
What is activated charcoal?
Wildly used in the treatment of toxicosis
* An adsorbent
* Binds most organic compounds, reducing their
absorption and facilitating their elimination in
feces
* Available in powder, gel or liquid
* Repeated doses are necessary for toxicants that
undergo enterohepatic recirculation
What are cathartics?
Enhance elimination of toxicants by moving
them through the GI tract more quickly.
What are bulk cathartics?
i). Bulk cathartics, e.g., psyllium (Metamucil), canned pumpkin or whole grain breads
* Have high fiber content to retain water in the lower GI tract and produce bulkier stools
What are osmotic cathartics?
ii). Osmotic cathartics, e.g., sorbitol
* Pull free body water into the GI tract
* Decrease total GI transit time
* Often combined with activated charcoal
What are saline cathartics?
iii). Saline cathartics, e.g., sodium sulfate
(Glauber’s salts) and magnesium sulfate (Epsom
salts)
– Stimulate GI motility
Cathartics should not be administered to
animals with:
– Pre-existing dehydration
– Electrolyte imbalances
– Diarrhea
What are enemas?
Enemas, e.g., warm soapy water or dioctyl
sodium sulfosuccinate (DSS)
– Eliminate toxicants from the lower GI tract
What is a gastric lavage?
Gastric lavage
- aims to empty stomach of toxic substance by sequential administration and aspiration of small vol of fluid via an orogastric tube.
– Requires general anesthesia and the use of a cuffed endotracheal tube
– May be necessary in potentially life-threatening oral exposures
– Activated charcoal can be instilled after the lavage
What is an enterogastric lavage?
Enterogastric lavage (through-and-through)
– Essentially Gastric lavage combined with retrograde high enema
– Stomach tube and endotracheal tube are placed and then an enema solution is instilled until it passes out from the stomach tube
What is a whole-bowel irrigation?
GI tract is cleaned by enteral administration of large volumes of osmotically balanced polyethylene glycol electrolyte solution (PEG-ES) until a clear liquid stool is achieved.
What is the function of a low enema? High enema?
Regular (low )enema washes out fecal matter from the area near the rectum, a high enema cleans out most of the colon
What is dermal decontamination?
- Wash the affected area or bathe entire animal
– Liquid hand dishwashing detergent is safe to use
– Repeated baths may be needed for heavily
contaminated animals - Vacuuming or combing to remove powders and
other dry compounds from skin - Shaving or clipping
- Mineral oil, vegetable oils, and peanut butter
can be used to remove items such as glue traps,
asphalt, and tree sap
How do you decontaminate inhalation exposures?
- Move patient to fresh air
- Administer supplemental oxygen and IV fluid
How do you decontaminate ocular exposures?
- Flush eyes with sterile saline solution or clean
room temperature water
– Sterile eye wash solutions are available in small
handheld bottles
– Bagged or bottled intravenous solutions can be used
What are some examples of Enhanced elimination procedures?
Gastrotomy and removal of toxicant (e.g., iron bezoar)
Urinary manipulation
Intravenous lipid emulsion (ILE)
Dialysis
- Urinary manipulation
– Forced diuresis - Administer a fluid overload and a diuretic concurrently or give a diuretic separately, e.g., mannitol or furosemide
- Useful for toxicants with high levels of renal excretion
– Ion trapping - Useful for weak acids and bases excreted predominantly unchanged through the kidneys. It is Achieved by urine acidification(ammonium chloride/DL-methionine) or alkalinization (potassium citrate)
- Intravenous lipid emulsion (ILE)
– For lipid-soluble toxicants - xenobiotics are ? and unavaioable for binding at site of action or target organs.
- Dialysis: hemodialysis, peritoneal dialysis, pleural dialysis, hemoperfusion
What are antidotes? What is their purpose? Explain how.
Antidotes counteract poisons. They prevent,
reverse, or decrease the action of a poison
– Limit absorption
– Sequester the toxicant
– Inhibit metabolism to a toxic metabolite
– Promote distribution from tissues
– Compete with poison for a receptor
– Counteract the toxic effect
– Enhance detoxification
What should you be mindful of when administering antidotes?
- There are no specific antidotes for the vast majority of the toxicoses
– Thus, treatment for most toxicoses is symptomatic and supportive: “Treat the patient not the poison” - Patient stabilization is the priority: Follow the ABC’s
- Antidotes are often expensive and unavailable
– Not enough profit to be made by manufacturers - Antidotes themselves can cause poisoning or
adverse reactions
What are chemical antidotes?
- Chemical antidotes
– Act directly on a toxicant to decrease toxicity or to increase excretion
– Include chelators, antibodies, and enzyme inhibitors
What are pharmacological antidotes?
- Pharmacological antidotes
– Antagonize or compete with the toxicant at its receptor site or through other macromolecules
– Can bind to the toxicant or target site to prevent toxicant from binding
What are functional antidotes?
- Functional antidotes
– Treat the symptoms caused by the toxicant (symptomatic care)
Antidotes can be in different classification groups
depending on the toxicosis they are used to treat
What are chelators?
What are antibodies?
- Comprise antitoxin-specific serum and
monoclonal antibodies. Include:
– Antivenin for some snakes (such as pit vipers and coral snakes)
– Antivenin for black widow spider
– Digoxin Specific Antibody Fragments (DigiFab) which binds to directly to it and inactivates it.
– Botulinum and tetanus antitoxins - They decrease the free form and tissue
concentration of the toxin, and increase its
elimination
What are enzyme inhibitors?
- Inhibit formation of toxic metabolites by either
competitive or irreversible inhibition
– Ethanol: competitive inhibitor of alcohol
dehydrogenase. Used to treat ethylene glycol
(antifreeze) toxicosis
– Fomepizole (4-methylpyrazole, 4-MP): competitive inhibitor of alcohol dehydrogenase for treatment of ethylene glycol toxicosis - Expensive and approval of the vet product (Antizol-vet ®) was withdrawn in 2015 at the request of the manufacturer
- Human product and compounded versions are available which can be used.
What is respiratory supportive care?
- Respiratory: artificial respiration, oxygen therapy
What is cardiovascular supportive care?
- Cardiovascular: antiarrhythmics, cardiovascular
drugs, IV fluids
What is neurologic supportive care?
- Neurologic: support respiration and circulation,
give sedatives or tranquilizers
What is GI supportive care?
- Gastrointestinal: antiemetics, GI protectants
(e.g., PPIs, H2RAs histamine recptor antagonists, sucralfate, misoprostol)
What is renal supportive care?
- Renal: maintain blood flow and urine output,
manipulate urine pH to hasten excretion of
toxicants
What is temperature supportive care?
Temperature: rewarm or cool patient
What is hepatic supportive care?
- Hepatic: administer hepatoprotectants [e.g., S-
adenosyl-L-methionine (SAMe), N-acetyl cysteine
(NAC), silymarin, vit C/E]
What is hematological supportive care?
- Hematological: correct electrolyte imbalances,
acid-base balance, blood volume (IV fluids or
blood transfusion), coagulation defects, oncotic
pressure
What is nutritional supportive care?
- Nutritional: enteral and/or parenteral nutrition
