Toxicologic Emergencies and Infectious Diseases

Introduction to Toxicology and Poisoning

• Definition of Poison: A poison is any substance that impairs health or causes death by its chemical action within the body.

• General Toxicology: Toxicology is the clinical study of toxins and their antidotes. Poisoning can be accidental or intentional (suicide or homicide).

• Overdose: This refers to an emergency involving poisoning by drugs, medications, or alcohol.

• Routes of Exposure:

  • Ingestion: Swallowing the substance (most common route).

  • Inhalation: Breathing in vapors, fumes, or gases.

  • Injection: Substance enters through a break in the skin (needles, bites, stings).

  • Absorption: Entry through the skin or mucous membranes.

• Patient Care Fundamentals: Most treatment for poisoning is supportive. EMTs must monitor mental status, airway, breathing, oxygenation, and circulation ($ABCs$). Be particularly prepared for sudden deterioration or vomiting.

Ingested Poisons

• Prevalence: Poisoning is the leading cause of accidental death among children. Most cases involve household products or medications.

• Common Substances:

  • Over-the-counter and illegal drugs.

  • Household cleaning agents and petroleum products.

  • Insecticides, plants, and spoiled/underprepared foods.

  • Medications taken in conjunction with alcohol.

• Signs and Symptoms:

  • History of ingestion and altered mental status.

  • Swelling, burns, or discoloration of the mucous membranes in the mouth.

  • Nausea, vomiting, diarrhea, and abdominal pain/tenderness.

  • Unusual breath or body odors.

  • Respiratory distress and altered heart rate or blood pressure.

  • Dilated or constricted pupils.

  • Seizures or coma.

• Odors Associated with Specific Toxins:

  • Hydrogen sulfide: Rotten eggs.

  • Naphthalene/Camphor: Moth balls.

  • Cyanide: Bitter almonds.

  • Acetone/Isopropanol: Fruity or sweet.

  • Organophosphates: Garlic.

  • Petroleum distillates: Gasoline.

  • Chloral hydrate: Pears.

  • Methyl salicylate: Mint.

  • Phosgene: Fresh mowed hay.

• Activated Charcoal:

  • Function: Absorbs certain toxins to prevent them from entering the bloodstream.

  • Dosage: Standard dose is $1\,g/kg$ of body weight; typical adult dose is $25\,to\,50\,g$.

  • Administration: Requires an order from medical direction. Place in a cup with a lid and a straw to improve patient compliance. Record the dose and exact time of administration.

  • Note: There is no definitive evidence it improves outcomes, and it must only be used with specific substances.

• Emergency Care: Maintain the airway, protect from aspiration (suction), and assist ventilation with Positive Pressure Ventilation ($PPV$) if breathing is inadequate. Bring the substance container to the hospital for identification.

Inhaled Poisons

• Overview: Poisons are rapidly absorbed into the body through the lungs. Prognosis worsens with longer exposure.

• Common Inhalants:

  • Ammonia, chlorine gas, and sulfur dioxide.

  • Carbon monoxide ($CO$) and Carbon dioxide ($CO_2$).

  • Industrial gases and fumes from liquid sprays or solvents.

• Huffing: Intentional inhalation of propellants or solvents. This can displace oxygen in the lungs and cause permanent damage to the alveoli.

• Signs and Symptoms:

  • Difficulty breathing, chest pain, tightness, or burning in the throat.

  • Cough, stridor, wheezing, crackles, or hoarseness.

  • Confusion, headache, dizziness, and seizures.

  • Soot in sputum/throat or singed nasal hairs (indicators of respiratory tract burns).

  • Paint, glue, or chemical residue on the face.

• Emergency Care:

  • Safety: Rescuers must use Self-Contained Breathing Apparatus ($SCBA$). Move the patient to a toxic-free environment immediately.

  • Oxygen: Administer high-flow oxygen via a nonrebreather mask regardless of the pulse oximeter reading. Assist with $PPV$ if breathing is inadequate.

Injected Poisons

• Sources: Intentional drug injection, and animal/insect bites or stings.

• Effects: Can be local (swelling at the site) or systemic (affecting the whole body). Anaphylaxis is a major risk with insect stings.

• Signs and Symptoms: Needle tracks, pain, redness, swelling, dizziness, chills, fever, nausea, vomiting, euphoria, or sedation.

• Emergency Care: Protect yourself from needles. Maintain airway and be alert for vomiting. Transport rapidly and maintain pulse oximeter saturation $\ge 94\%$.

Absorbed Poisons

• Mechanism: Corrosive or toxic substances that enter through the skin or mucous membranes causing irritation or chemical burns.

• Signs and Symptoms: Traces of powder or liquid on skin, burns, itching, rash, or oozing blisters (common with poisonous plants like oak, ivy, and sumac).

• Emergency Care:

  • Powdered Toxins: Brush dry powder off the patient, then flush with clean water.

  • Liquid Toxins: Flush with clean water for at least $20\,minutes$.

  • Eye Exposure: Irrigate chemical burns of the eye with clean water for a minimum of $20\,minutes$.

  • Safety: Wear gloves and remove contaminated clothing before treatment.

Specific Toxicological Emergencies

• Food Poisoning:

  • Sources: Seafood, eggs, chicken, unpasteurized milk, and untreated water.

  • Pathogens: Salmonella, Campylobacter, Escherichia coli ($E.\,coli$), and Staphylococcus aureus.

  • Signs: Fever, blood in stool, abdominal cramping, and loud bowel sounds.

• Carbon Monoxide ($CO$):

  • Properties: Colorless, odorless, tasteless, and nonirritating gas from incomplete combustion.

  • Pathophysiology: Displaces oxygen on hemoglobin. Note that pulse oximeter readings will be falsely high because the device cannot distinguish between carboxyhemoglobin and oxyhemoglobin.

• Cyanide:

  • Sources: Rodent poisons, silver polish, fruit pits, and burning plastics/silks.

  • Action: Interferes with oxygen utilization at the cellular level despite adequate blood oxygenation.

• Acids and Alkalis:

  • Acids: Low $pH$; burn on contact for $1\,to\,2\,minutes$.

  • Alkalis: High $pH$; burns may be delayed in sensation but can last for hours (e.g., lye).

• Hydrocarbons: Found in kerosene, lighter fluid, and glue. High risk of aspiration pneumonia.

• Methanol: Found in gasoline and antifreeze. Ingestion causes severe metabolic acidosis and blindness.

• Isopropanol (Isopropyl Alcohol): More toxic than ethanol; causes respiratory depression and bloody vomitus.

• Ethylene Glycol: Found in deicers/antifreeze; has a sweet taste. Metabolites damage the Central Nervous System ($CNS$), heart, and kidneys across three clinical stages.

Drug and Alcohol Emergencies

• Drug Abuse Definitions:

  • Tolerance: Larger doses required to achieve the same effect.

  • Dependence: Physical or psychological need for repeated use. Physical withdrawal signs occur when the drug is absent.

• Drug Classifications:

  • Stimulants (Amphetamines, Cocaine): Cause tachycardia, hypertension, paranoia, and seizures.

  • Cannabis (Marijuana, THC): Euphoria, dry mouth, and disorientation.

  • Depressants/Narcotics (Opioids, Heroin, Morphine): Miosis (constricted pupils), bradycardia, and respiratory depression.

  • Hallucinogens (LSD, PCP, PCP): Psychosis, flashbacks, and poor perception of time/distance.

• Alcohol Withdrawal Syndrome:

  • Stage 1: Tremulousness, insomnia, nausea (within $8\,hours$).

  • Stage 2: Hallucinosis (within $8\,to\,72\,hours$).

  • Stage 3: Withdrawal seizures (characterised by rhythmic muscle rigidity; occurring as early as $48\,hours$).

  • Stage 4 (Delirium Tremens): Severe confusion, memory loss, terrifying hallucinations, and extremely high fever. Mortality rate of $5\%\,to\,15\%$. Occurs most commonly $2\,to\,5\,days$ after the last drink.

• Opioid Emergency Management: Administer naloxone intranasally ($2\,mg$ total; $1\,mg$ per nostril) if protocol allows to reverse respiratory depression.

Infectious Diseases

• Hepatitis B: Affects the liver; contracted through blood/fluids. Chronic carriers are the primary source. Signs include Jaundice (yellowing of skin/eyes) and dark urine.

• Hepatitis C: Most common bloodborne infection in the US. $80\%$ of patients are asymptomatic.

• Tuberculosis ($TB$): Found in lungs. Use HEPA/N-95 masks to avoid infected droplets. Symptoms: night sweats and coughing up blood.

• HIV/AIDS: Transmitted via blood, semen, needles, or mother-to-child ($12th\,week$ gestation). Not spread via casual contact.

• West Nile Virus ($WNV$): Mosquito-borne. Severe signs: stiff neck, paralysis, and vision loss.

• Ebola: A viral hemorrhagic fever. Causes severe vomiting/diarrhea and unexplained hemorrhage.

• Zika Virus: Mosquito-borne. Key danger is transmission to pregnant women causing birth defects.

• Multidrug-Resistant Organisms: Pathogens that resist standard antibiotics, including $MRSA$, $VRE$, and $MDRTB$.

COVID-19 Pathophysiology and Management

• Mechanism: The virus enters through nasal passages; spike proteins connect with $ACE2$ receptors. Leads to "pyroptosis" (programmed cell death) and inflammation that fills alveoli with fluid, causing Acute Respiratory Distress Syndrome ($ARDS$).

• Clotting Issues: The inflammatory process causes micro-emboli to form, which can lead to organ failure in the kidneys, brain, and liver.

• Clinical Stages:

  • Stage 1: Asymptomatic ($1\,to\,2\,days$).

  • Stage 2: Upper respiratory symptoms.

  • Stage 3: Alveolar infection and severe inflammatory response.

• Multisystem Inflammatory Syndrome ($MIS$): Rare but serious condition affecting children ($MIS-C$) or adults ($MIS-A$) presenting with fever, chest pain, and hypotension.

• PPE for EMS: Use $N-95$ masks, eye protection, and gowns for aerosol-generating procedures (e.g., $BVM$ ventilation, suctioning, $CPAP$, or Intubation).

• Transport: Notify the hospital in advance. Isolate the driver compartment; use the rear exhaust fan on high to create negative pressure in the patient compartment with ventilation set to non-recirculate.

Questions & Discussion

• Case Study #1: John (2-year-old boy): John was found with lamp oil around his mouth. EMTs prioritized removing his oil-soaked clothes and rinsing him in the bathtub. Poison Control recommended transport due to the potential for hydrocarbon exposure and aspiration, evidenced by his history of coughing.

• Case Study #2: Warren (Traveler): Warren experienced vomiting and diarrhea after a buffet. He had a positive orthostatic tilt test, indicating dehydration. He was treated with IV fluids and anti-nausea medications.

• Case Study #3: Vince (Paint Huffing): Vince was found with gold spray paint on his face and was disoriented (history of schizophrenia). EMTs noted scattered wheezing and an irregular heart rate. They administered $4\,L/min$ of oxygen via nasal cannula.

• How to manage a violent patient?: Use the "talk-down technique." Maintain a nonjudgmental attitude, stay focused on the patient, and use a calm voice to decompress the situation.