Toxicology Flashcards
What is the impact of epidemiology of poisoning on clinical decisions?
It informs the approach to treatment and management of poisoned patients.
What should be obtained from a poisoned patient to aid in treatment?
A thorough history, understanding its limitations.
Define ‘toxidrome’.
A group of signs and symptoms and/or characteristic effects associated with exposure to a particular substance or class of substances.
What are the signs of Opioid Toxidrome?
- Tiny pupils
- Respiratory and CNS depression
- Hypoactive bowel sounds
What is the recommended treatment for Opioid Toxidrome?
Naloxone (NARCAN™️)
List the symptoms of Anticholinergic Toxidrome.
- Psychosis
- Dry mucous membranes, urinary retention
- Elevated temperature
- Flushed skin
- Mydriasis
What is the treatment for Anticholinergic Toxidrome?
Physostigmine (use with caution)
What is the Cholinergic (Muscarinic) Toxidrome?
A toxidrome characterized by symptoms such as diarrhea, urination, miosis, bronchorrhea, emesis, lacrimation, and salivation.
What is the treatment for Cholinergic Toxidrome?
Atropine and Pralidoxime
What age group accounts for half of all poisonings?
Children age 1-5
Differentiate between poisoning, intoxication, and overdose.
- Poisoning: Exposure to harmful agents
- Intoxication: Ill-defined term often confused with inebriation
- Overdose: Exposure to pharmacologic substances in suprapharmacologic doses
What routes of exposure may allow for gastrointestinal decontamination?
- Oral
- Transcutaneous
- Inhaled
- Intravenous
- Transmucosal
What are five methods of gastrointestinal decontamination?
- Induced emesis (Syrup of Ipecac)
- Gastric lavage
- Activated charcoal
- Whole bowel irrigation
- Cathartics
What should be considered when deciding on gastrointestinal decontamination?
- Polypharmacy overdoses
- Overdose of substances without specific antidote
- Known or suspected lethal ingestions
What is the survival rate for poisoning cases?
99.8%
True or False: Gastric lavage should be used for all poisonings.
False
What are the risks associated with gastric lavage?
- Aspiration
- Esophageal or gastric perforation
- Decreased oxygenation
- Pneumomediastinum/mediastinitis
What is activated charcoal considered?
The best approximation of a ‘universal antidote’
What are the contraindications for activated charcoal?
- Absent gut motility or perforation
- Caustic ingestions
- Xenobiotics that do not adsorb to charcoal
What are the complications associated with activated charcoal?
- Fatal aspiration
- Small bowel obstruction
- Interference with oral antidotes
What factors indicate ongoing absorption of toxins?
- Recognized high-risk ingestions such as cyanide, colchicine, chloroquine, aspirin, cyclic antidepressants, verapamil, paraquat
Fill in the blank: The removal or binding of a toxin in the GI tract is called _______.
Gastrointestinal decontamination
What are some rare complications of activated charcoal?
- Fatal aspiration
- Small bowel obstruction
- Pneumonitis
- Interference with oral antidotes
- Interference with oral maintenance medications
Complications may arise from activated charcoal administration, particularly in cases of overdose or improper use.
What is a small bowel charcoal bezoar?
A bezoar causing small bowel obstruction after repeated activated charcoal administration
This condition can occur when activated charcoal accumulates in the gastrointestinal tract.
What does MDAC stand for?
Multiple Dose Activated Charcoal
MDAC is a method used to enhance the elimination of certain toxins from the body.
What is the mechanism behind MDAC?
Substances that have already entered the systemic circulation may be pulled back into the gut by activated charcoal if they undergo enterohepatic or enteroenteric circulation, are present in significant amounts in circulating blood, and can be absorbed by charcoal
This process allows for the re-absorption of toxins that might otherwise remain in the bloodstream.
What drug’s toxicity has proven efficacy with MDAC?
Theophylline
Theophylline is known for its narrow therapeutic window and can cause significant toxicity.
What are common symptoms of Theophylline toxicity?
- Agitation
- Delirium
- Tachycardia
- Hypertension
- Tremulousness
These symptoms represent the toxidrome associated with Theophylline overdose.
What is Whole Bowel Irrigation (WBI)?
Mechanical cleansing of the entire GI tract by the instillation of large volumes of fluid
WBI is used to eliminate toxins that charcoal cannot effectively absorb.
What is the preferred solution for WBI and why?
Polyethylene Glycol (PEG or Golytely™) because it does not cause electrolyte disturbances
This makes PEG safer for patients undergoing bowel irrigation.
What are indications for Whole Bowel Irrigation?
- Potentially toxic ingestion of a substance not well absorbed by charcoal
- Substances with prolonged absorption phase
- Rising drug levels despite gastric emptying
WBI is particularly useful in cases where traditional methods of decontamination have failed.
What are the contraindications for Whole Bowel Irrigation?
- Absent bowel sounds
- Bowel obstruction
- Persistent vomiting
- Unprotected airway
- Signs of leakage of body packers’ packets
Contraindications highlight the risks of performing WBI in certain clinical situations.
What are common cathartics used in conjunction with activated charcoal?
- Magnesium
- Sorbitol
These substances can assist in expelling toxins from the gastrointestinal system.
What is a reasonable take-home message regarding GI decontamination?
GI decontamination is dangerous and should be used for patients with life-threatening ingestions
It has not consistently shown to change outcomes, but early intervention is preferred.
True or False: GI decontamination has consistently shown to improve patient outcomes.
False
The effectiveness of GI decontamination in changing outcomes has not been conclusively demonstrated.
What is the primary learning objective regarding acid and alkali ingestions?
Differentiate the pathophysiology and prognosis between acid and alkali ingestions
What are the common signs of caustic ingestions?
Nausea, vomiting, drooling, pain
Ominous signs include stridor, respiratory distress, lethargy, hematemesis, peritonitis
What is a caustic?
A substance that causes both functional and histologic damage on contact with tissue surfaces
How are caustics typically classified?
Acid, alkali, other
What type of necrosis is produced by acids?
Coagulation necrosis
What type of necrosis is produced by alkalis?
Liquefaction necrosis
What factors influence the extent of injury from caustic ingestions?
Extremes of pH, duration of contact, volume, concentration
What imaging should be obtained early in serious caustic ingestions?
CT scanning
What are the benefits of CT scanning in caustic ingestions?
More sensitive for evaluation of viscous perforation than plain films
What is the recommended management approach for caustic ingestions?
Multi-disciplinary approach involving anesthesia, ENT, gastroenterology, pulmonary/critical care, and surgery
What is the controversy regarding the use of steroids in caustic ingestions?
Theoretical benefit to prevent strictures, but their use is controversial and not recommended
What are the predictors of grade IIb and III injury in caustic ingestions?
2 or more of the following: stridor, pain, vomiting, drooling, dysphagia, oral burns
What is the significance of button battery ingestion?
True emergency if impacted; can cause necrosis in 6 hours
What are the common clinical features of foreign body ingestion?
Pain, drooling, vomiting, inability to drink
What is the recommended management for impacted esophageal foreign bodies?
Emergent endoscopic removal
Fill in the blank: Acids cause _______ necrosis.
coagulation
Fill in the blank: Alkalis cause _______ necrosis.
liquefaction
What is the diagnostic modality of choice for foreign body ingestion?
CT scan
What is the management for button batteries that have passed the pylorus?
Expectant management with follow-up mandatory in 24 hours
True or False: Caustic oral lesions predict distal injury.
False
What should be avoided in the management of caustic ingestions?
GI decontamination and neutralization
What is the primary cause of complications from button battery ingestion?
Pressure causing ischemia, chemical leakage, electrical current
What should be done if a button battery is lodged at the cricopharyngeus?
Immediate endoscopic removal
What is the significance of visible lesions in children after caustic ingestion?
May allow omission of endoscopy in completely negative pediatric patients
What is a common complication of foreign body ingestion?
Aspiration, erosion, perforation, strictures, hemorrhage
What is the mainstay of therapy for most cases of ingested foreign bodies?
Endoscopic removal
What routes of exposure may be amenable to irrigation
transcutaneous only
what routes of exposure may be amenable to GI decontamination
oral only
what routs of exposure may be amenable to hemodialysis
inhaled agents; intravenous; transmucosal
What drug should only be used for KNOWN iatrogenic overdoses?
Flumazenil: benzodiazepine
what is the most important question to ask a pt. when GI poisoning or OD are suspected
WHEN?
what question is especially important for pediatric pts. when GI poisoning or OD are highly suspceted
WHERE?
what poisons can be detected on Plain films
hydrocarbons; heavy metal exposures; iron, isoniazide; solvents; enteric coated pills; haloperidol
medically induced gastric emptying should be implicated for potentially lethal ingestions; List the high-risk agents.
cyanide; chloroquine; aspirin; TCAs; verapamil; colchicine
Lethal Ingestion of which substances would not be very effectively removed due to rapid absorption into the blood stream
ethanol
acetaminophen
drugs with delayed absorption can be implicated for gastric emptying; which ones are pertinent for your upcoming exam
Anticholinergics; sedatives; opioids
gastric lavage should only be implicated under what circumstances
the lethal ingestion is known
exposure < 1hr. ago
If TCA OD is ascertained what technique could be applied due to rapid deterioration of OD
gastric lavage
Gastric lavage can also be implicated for drugs in which case even the slightest decrease in exposure may be critical; what ones will be on your exam next week?
CCBs
Colchicine
Lithium
what substances will not be absorbed by charcoal
strong acids & bases; alcohols; iron; lithium
what pharmacokinetic profiles are the most ideal for MDAC
concretion
low volume of distribution
low-protein binding
long half-life
body packers can be implicated for WBI unless what has transpired
leakage of the body pack contents in which case requires surgery instead
what OTC chemical solution is the most common cause of Alkali poisoing
drain cleaners
