Valentovic - Poisoning and Overdose Flashcards
For the initial exam, the following should be determined first:
- Identify toxins
- Estimate dose
- Determine status of respiration and circulation
(worsened with a previous disease state!)
Deaths from acute poisoning are usually due to ___________ and ____________
Cardiovascular complications (cocaine, methamphetamine) and depressed respiration (barbiturates, opiates, alcohol)
Most common poisonings in children < 5 years of age:
-
-
-
-
- Fe containing vitamins
- Pesticides
- OTC cold remedies
- Cleaning supplies
Most common poisonings in people >18 years of age:
-
-
-
-
-
- Analgesics
- Sedatives/hypnotics
- Substance abuse
- Antidepressants
- Alcohol
* or combination of the above
Supportive care:
- Essential to maintain ______ and _____
- People die from respiratory depression (HYPOXIA!) - respiration further decreased by mixing: _____, _____, ____ or _____ (respiratory depressants)
- Circulation can be modified by: ____, ____, ____
- Circulation and respiration
- Barbiturates (relax vascular smooth muscle so dec BP), Opiates, Benzodiazepines, or Alcohol
- Cocaine, Carbon Monoxide, Opiates (dec HR)
Need to remove toxin to prevent further absorption into the body - e.g. most common exposures:
- carbon monoxide - ________
- drugs - ________
- Solvents, pesticides - ________
Enhance elimination - alkalinize urine for acidic drugs
Use antidote or antagonist
- Inhalation
- Ingestion
- Dermal (industrial accidents)
What method for terminating exposure to a toxin:
- Mechanical (finger, spoon) is not effective for removing stomach contents –> only gives you a gag reflex
- Use syrup of Ipecac**
- For ingestion of acetaminophen, ASA, antihistamines, vitamins, cold remedies, benzodiazepines, pesticides [Paraquat]
Emesis
What is the mechanism of action of Syrup of Ipecac?
- Irritates the stomach
- Rapidly absorbed, stimulates the CTZ (chemoreceptor trigger zone) in the Brain
- results in nausea and vomiting
* Occurs within ~30 minutes
What are some contraindications for emesis?
****Don’t use emesis when toxin is more dangerous when aspirated!
- Corrosive agents (Drain cleaner, ammonia or electric dishwasher cleaner)
- Loss of gag reflex (can aspirate)
- Comatose (can aspirate)
- Sharp objects - e.g. glass (do surgery!)
- Agents associated with seizures
- TCAs, GHB, Strychnine [all lower the seizure threshold]
- Ingestion of hydrocarbons (furniture polish)
What method for terminating exposure to a toxin:
- Agent is activated and added to lavage fluid to enhance removal of toxins
- Adsorbs drugs, then the mixture is removed by lavage or through feces
- Uses: acetaminophen, aspirin, amphetamines, benzodiazepines, digoxin, opiates, malathion, nicotine, syrup of ipecac
***Use syrup of ipecac first, then add this method on.
Lavage and Activated Charcoal
Lavage and activated charcoal are not used for what toxins?
- Corrosives (draino, ammonia)
- Caustic agents
- Acids, Alkali, Most metals or Petroleum distillates
- Alcohols
What antagonist?
- For opiate overdose (codeine, heroin, morphine)
- Competitive, reversible antagonist at mu receptor
- short half-life, so sometimes have to give multiple times
- To reverse respiratory depression of opiates****
Naloxone
What antagonist?
- Benzodiazepine overdose (diazepam, oxazepam, etc)
- Competitive, reversible antagonist at benzo receptor
- Reverse respiratory depression so individual won’t die from hypoxia
Flumazenil
________: used to alkalinize urine, to enhance the excretion of acidic drugs
- e.g. Barbiturates, ASA (salicyclic acid)
**** Acidification of urine for alkali drugs is not effective bc body compensates to easily.
Sodium Bicarbonate
What toxin?
- Major target is aspiration into lungs –> chemical-induced pneumonitis
-
Poisonings mostly in children < 3 years old
- Most common: household solvents - gasoline, mineral spirits (paint thinner), furniture polish, kerosene
Petroleum distillates
Risk of aspiration is dependent upon what 3 factors?
******Which one is the best determinant of aspiration potential of petroleum distillates?
- Viscosity - best determinant******, expressed in SUS units
- Volatility
- Surface tension
******Viscosity and aspiration risk are inversely related
(low viscosity or SUS unit = high aspiration risk)
What determinant of aspiration potential?
A. Low levels allows for spread from mouth to trachea and lungs (e.g. siphoning gasoline)
B. Displaces oxygen from alveoli, leads to hypoxia
movement from liquid to gas
A. Surface Tension
B. Volatility
What type of abuse?
- Inhalation of paint, glue, spray cooking oil, lighter fluid, gasoline, toluene
- Death due to cardiac arrest or hypoxia –> Permanent brain damage [affects membrane fluidity]
- Solvents are absorbed through your lungs –> get in to blood stream to your heart –> effect membrane fluidity –> effecting muscle contractility of the heart –> speeds up heart –> arrhythmia and cardiac arrest
- May cause rash!***** (from solvents around the face)
Huffing - abuse of aerosol propellants
Acetaminophen toxicity -
- First 24 hours have minor GI upset, nausea
- After 24-48 hours, hepatic damage appears
- Excellent correlation of acetaminophen blood levels with ___________
Time expired since ingestion and prediction of toxicity
Alcohol ——> ____________ —> _____________
*What enzymes, what products?
Alcohol——> Acetaldehyde (via Alcohol dehydrogenase)
Acetaldehyde —> Acetate (via Aldehyde dehydrogenase)
** Acetate to Krebs Cycle
Aspirin is converted to the toxic agent, __________
- Can then be converted to:
- Acyl glucuronides, Phenyolic glucuronides
- Salicyluric acid (glycine conjugate)
- Gentisic acid –> Gentisuric acid
Bonus: What order kinetics does toxicity follow?
Salicylic Acid
Bonus: Zero order!
bc no P450 metabolism, the conjugation reactions become saturated
and that’s why you go to zero order in overdose.
*****What do you measure for determining salicylate toxicity on a nomogram?
* Good correlation with time of ingestion and prediction of severity of toxicity
PLASMA SALICYLATE CONCENTRATION! ******
