Poisoning and Overdose Overview

Poisoning & Overdose Definitions

• Poison: any substance that impairs normal metabolic processes upon contact or introduction into an organism, altering organ and tissue function.
  • "Everything is a poison, it is a matter of dose." (Alchemist’s Rule)
• Overdose: excessive use of any drug causing acute adverse physical or mental effects.
  • Can be deliberate or accidental, lethal or non-lethal.

Routes of Entry

• Inhalation: Airborne substances breathed in, including gases, vapors, smoke, fog, dust, mists, and fumes. (rapid absorption)
• Absorption (Skin and Mucous Membranes): Includes the eyes, generally slower than inhalation. Intact skin provides a barrier to some, but not all, poisons.
  • Affected by blood flow and temperature to the area.
  • Lipid-soluble chemicals (organophosphates) readily absorb through skin.
• Ingestion: Patient must have been awake to take the substance.
  • Intentional: suicide or poisoning by another.
  • Unintentional: improper hand washing, smoking, eating, swallowing concentrated solids or liquids, or inhaling aerosols.
  • Most common in children.
• Injection: Subcutaneous, intramuscular, or intravenous.
  • IV drug use, accidental high-pressure injection, lacerations, prescribed medication.

Degree of Poisoning

• Factors affecting the degree of poisoning include:
  • Concentration of the substance
  • Exposure time
  • The substance's affinity for tissue
  • Sensitivity of the exposed tissue
  • Route of entry
  • Age
  • Liver function.

Alcohol

• Isopropanol, methanol, and ethanol (ETOH) are common alcohol types.
• Ethanol Withdrawal: Can be fatal.

Alcohol ADME

• Usually ingested, but can be absorbed parenterally through inhalation, rectal, or IV administrations.
• Distributed equally through all water-carrying potential spaces.
• Metabolized primarily through 2 enzymes:
  • Alcohol dehydrogenase: Converts ethanol to Acetaldehyde.
  • Aldehyde dehydrogenase: Converts Acetaldehyde to ketones.
• 95% is metabolized, the remaining 5% excreted through sweat, urine, and respiration.

Alcohol MOA

• Binds to GABA receptors, a receptor protein causing CNS depression.
• Continuous GABA stimulation increases the stimulus threshold.
• More ETOH is needed to achieve the same effect as dependency increases.
• Subclinical symptoms are caused by depression of specific areas of the brain responsible for coordination, memory, logic, consciousness, respiration, and airway protection.

Household Poisons

• CO and Cyanide: Failure of cells to carry out aerobic respiration, leading to lactic acidosis, cell death, MODS, and patient death.
  • Tx: 100% oxygen, hyperbaric chamber, cyanocobalamin (vitamin B12).
• Food Poisoning: Bacteria in food causes gastroenteritis, generally self-limiting. Risk of hypovolemia from excessive vomiting may require IV fluids.
• Blister Agents: Chemicals like Ammonia Cleaner and Chlorine Bleach cause direct trauma to the respiratory system, leading to inflammation, pulmonary edema, hypoxia, and death.
  • Tx: High-flow oxygen and rapid transport before tissue damage overwhelms basic life support (BLS) airway management.
• Do not enter a potentially unsafe scene before the scene is cleared or the patient is brought outside.

Rx Drugs - Salicylates

• Used primarily to treat inflammation (ASA, Bengay, Oil of Wintergreen, Pepto Bismol).
• Fatal dose for an average 14kg toddler:
  • 21 adult ASA tablets
  • 1 teaspoon Oil of Wintergreen
  • 1 bottle Pepto Bismol

Rx Drugs - Salicylates

• Salicylates cause damage through two primary mechanisms:
  • Direct neural tissue poisoning.
  • Dramatically increased metabolism and breakdown of fuel sources in the body while inhibiting aerobic respiration.
• S/S by stage:
  • Early: 4-12 hours: Tinnitus, nausea/vomiting/diarrhea, diaphoresis, respiratory alkalosis.
  • Transitionary: ~24 hours: Worsening symptoms, agitation, delirium, hyperthermia, dehydration.
    • Pediatric: ~4 hours: metabolic acidosis, rhabdomyolysis.
  • Late: Seizures, coma.

ASA (Acetylsalicylic Acid)

• Tx: Supportive care, airway management during seizures, manage hyperthermia, rapid transport for gastric lavage if acute ingestion.

Rx Drugs - Acetaminophen

• Anti-inflammatory and antipyretic.
• Death occurs due to direct liver damage, occurring ~12 hours post-ingestion.
• With early treatment (< 8 hours), minimal damage occurs.
• Lethal Dose: 150mg/kg or 10g adults
• Toxic Dose (Acute Ingestion): Tylenol extra strength - 20 tablets

Rx Drugs - Acetaminophen

• Acetaminophen Toxicity: Large amounts of acetaminophen overwhelm normal metabolism and take a side pathway creating a toxic metabolite, eventually causing liver damage.
• Tx: N-Acetylcysteine (NAC): given within 8 hours at the hospital to join with the toxic metabolite to create a safe metabolite that can be excreted by the body.

Rx Drugs - Cholinergics-Organophosphates

• Organophosphate poisoning causes overstimulation of cholinergic receptors, leading to problems with the muscarinic and nicotinic junctions.

Organophosphate Poisoning

• Muscarinic Effects (SLUDGEM):
  • Salivation
  • Lacrimation
  • Urination
  • Defecation
  • Gastrointestinal distress
  • Emesis
  • Miosis
  • Bradycardia
  • Bronchospasm
  • Emesis
  • Lacrimation
  • Salivation
• Nicotinic Effects (MTHWF):
  • Mydriasis (pupil dilation)
  • Tachycardia
  • Weakness
  • Hypertension, hyperglycemia
  • Fasciculations

Organophosphate Poisoning

• Immediate danger: Respiratory paralysis and seizures due to constant stimulation by Ach at the neuromuscular junction.
• Characteristic Sign: Muscle fasciculations at 22 seconds

Organophosphate Poisoning

• Tx: Standard care, airway management, oxygenation, aggressive fluid boluses to maintain blood pressure (systolic 90, or MAP 65), Atropine, Versed.

Anticholinergic Poisoning

• Decreases the strength of acetylcholine (Ach) at the muscarinic junction through increased acetylcholinesterase (AchE) or competitive inhibition.
• Clinical Manifestations:
  • Dry As A Bone: dry skin, eyes, mouth, and mucous membranes.
  • Red As A Beet: flushing and fever
  • Mad As A Hatter: Confusion and delirium.
  • Hot As A Hare: Hyperthermia
  • Blind As A Bat: Mydriasis (dilated pupils)

Treatment for Poisoning

• Ensure scene safety.
• Decontamination is paramount:
  • Begin before initial medical management.
  • Remove all clothing and irrigate exposed areas to remove residual material from the skin.
  • Treat the patient in a well-ventilated room or outside.
  • Maintain appropriate barrier protection and ventilation to prevent secondary casualties.
  • Decontaminate yourself AND your truck.

Treatment for Poisoning

• Airway management.
• Oxygen.
• Contact poison control.
• IV therapy.
• ECG.
• ALS backup.
• Notify receiving treatment center so a secondary decontamination area can be set up.

Management of Overdose Patient

• Scene safety.
• Level of consciousness (LOC) assessment. (Must be continually reassessed.)
• Airway management.
• Oxygen.
• IV therapy.
• ECG.
• Continual reassessment and symptom management.
• Assess for any other injuries.

Explore the critical concepts of poisoning and overdose, focusing on definitions, routes of entry, and implications. Understand how different substances affect the body and the various methods they can enter the system. This quiz will enhance your knowledge of toxicology basics.