EHS 202 Pharmacology Week 6

EHS 202 Pharmacology for EMS - Week 6

• Poisonings and overdoses are a significant portion of EMS responses
• Overdoses can be associated with trauma, suicide attempts, psychiatric illness, or other medical emergencies.
• Objectives of the lecture include defining overdose in paramedic practice, assessment and management of common toxins, physiological effects of overdose toxins, and clinical guidelines for overdose management.
• Toxicological emergencies are a common reason for ambulance calls and can present unique challenges.
• Not all overdose and poisoning cases are reported, especially intentional or illegal incidents.
• Management of toxicological emergencies requires paramedics to think critically about safety, the source of the substance, differential diagnosis, and treatment plans.
• Toxicological emergencies may not always be drug-related. Paramedics need a solid understanding of substances and medications, pharmacokinetics, and pharmacodynamics in pre-hospital settings.
• Exposure can be via ingestion, inhalation, topical, absorption, injection, inoculation, or radiation.
• Accidental overdoses are common among young children, often due to inadequate supervision.
• Intentional overdoses are commonly associated with self-harm, suicide attempts, psychiatric illness, or other medical emergencies.
• Toxicology is the study of toxic or poisonous substances.
• A poison is a substance that damages structures or reduces normal body function, even in small amounts.
• A drug has therapeutic effects (e.g., pain relief, fighting infection), but in excess, it can become poisonous.
• A toxin is a harmful substance naturally produced by a living organism (e.g., bacteria, plants, animals).
• Overdose occurs when a drug or substance is taken in excess, whether legal or illegal.
• The severity and outcome of overdoses/poisonings depend on the patient's age, weight, the toxicity of the substance, quantity, route of exposure, and co-morbidities.
• Common overdose types include over-the-counter or prescribed medications, alcohol, and opiates. Paramedics must be familiar with these various presentations and treatment strategies.

Case Study

• A collapsed male patient, unconscious, was reported to EMS by police.
• The patient was approximately 30 years old, lying prone, unresponsive except to pain.
• Respiratory rate was 10, with shallow breathing; reduced tidal volume.
• Blood pressure was 110/72, heart rate 120 bpm.
• The patient showed signs of intoxication (needle marks and scars on arms).
• Drug paraphernalia, needles, and an unknown brown substance (believed to be heroin) were present.

Scene Safety

• Personal and environmental safety are paramount at emergency calls.
• Paramedics have a duty of care to provide safe environments for patients and others involved.
• Balancing patient care with safety concerns is a critical ethical consideration.

Approach to Every Scene

• Paramedics need to assess danger, response, airway, breathing, and circulation.
• Risk factors should be considered during the reassessment.
• Additional risk factors like violence, sharps injuries, exposure to blood-borne infections like hepatitis and HIV must be considered.

Common Drugs of Abuse

• Commonly abused drugs include Narcotics (opiates and opioids), Sedatives/Hypnotics/Central Nervous System depressants, Sympathomimetics/Central Nervous System stimulants, and Anticholinergics.
• Prescription drugs associated with overdose include opiates (morphine, codeine, oxycodone, fentanyl, tramadol), antidepressants (amitriptyline, seroxat, citalopram, sertraline) and benzodiazepines (diazepam, tamazepam, midazolam); non-benzodiazepines (zopidem, zopiclone, zaleplon) and gabapentinoids (gabapentin & pregablin).

Narcotic, Opioid, Overdose

• Overdose can result from any opiate in any setting.
• Opiates depress the respiratory and circulatory systems, resulting in reduced consciousness or hypotension and respiratory depression.
• Paramedics must focus on airway, breathing, and circulation management when dealing with suspected opiate overdose.
• Heroin is a common causative agent in opiate-related overdoses, can be injected, snorted or inhaled.

Opiate Overdose Management

• Determining the cause of altered consciousness (ruling out other metabolic conditions), and administering naloxone.
• Naloxone is a competitive antagonist that binds to opiate receptors, preventing their effects.
• Naloxone is administered intravenously, intramuscularly, intraosseously, or subcutaneously.
• Rapid administration or excessive dosages can lead to violent withdrawal reactions, agitation, and vomiting, impacting airway compromise and increasing safety risks.
• Dosage guidelines for adults (>= 12 years) and children ( <12 years) are provided separately.

Central Nervous System (CNS) Depressants

• Common CNS depressants are benzodiazepines, barbiturates, anesthetic agents, inhalational solvents, and alcohol.
• Overdose results in CNS depression causing drowsiness, confusion, loss of coordination, decreased blood pressure and respiration.
• Benzodiazepine intoxications are less severe than barbiturate overdoses.
• Flumazenil is a benzodiazepine antagonist used to reverse the sedation and respiratory depression caused by benzodiazepine overdose.
• Activated charcoal is useful in barbiturate overdoses.

Alcohol Intoxication Management

• Intoxication can affect body temperature, breathing, heart rate, and gag reflex.
• Patients with reduced GCS risk aspiration and may not be able to consent to treatment.
• Alcohol withdrawal can lead to seizures and delirium tremens.

CNS Stimulants (Methamphetamine & Cocaine Intoxication)

• These drugs are chemically similar to the body's natural catecholamines (adrenaline, noradrenaline and dopamine).
• Overdose leads to sympathomimetic effects (hypertension, tachycardia, cardiac arrhythmias, dilated pupils, increased activity, restlessness, seizures, and excess body temperature, mood swings, violence).

CNS Stimulant Intoxication Management

• Includes tachycardia, hypertension, chest pain, and myocardial ischemia.
• If ischemic chest pain is present, management needs oxygen, aspirin, GTN, and a 12-lead ECG.
• Diazepam should be administered for severe chest pain (following local guidelines).
• Benzodiazepines are used for seizures.

Activated Charcoal

• Should be the first intervention for oral overdoses and poisonings.
• Reduces poison absorption and may induce vomiting.
• Follow appropriate risk assessments before administering.
• It's not applicable in all ingestion cases as some ingested substances are not affected by charcoal.
• Contraindicated in cyanide, petroleum distillates, lithium, iron, ethanol, and corrosive substances.

Paracetamol (Acetaminophen) Overdose

• Paracetamol (Panadol, Tylenol) overdose can lead to significant liver and kidney damage.
• Patients with pre-existing liver conditions or heavy alcohol use are more vulnerable.
• Typical symptoms in overdose include right upper quadrant pain, nausea, vomiting, jaundice, confusion or loss of consciousness.
• Clinical symptoms may not be immediately apparent.
• Initial care is the same as for other ill/injured patients (maintain airway, administer oxygen, place IV line)
• Treat hypotension with IV sodium chloride and consider activated charcoal (if ingestion occurred within the hour).
• Consider naloxone if respiratory depression is present.

Cyclic Antidepressant Overdose

• Overdoses of cyclic antidepressants are dangerously severe, especially in children.
• Manifestations include CNS excitability, fever, pupil dilation, seizures and loss of consciousness, arrhythmias, tachycardia, and respiratory depression.
• Initial care is supportive; activated charcoal may be administered (if allowed), and cardiac arrhythmias are a serious concern.
• IV fluids may not be enough for severe hypotension. Vasopressors may be needed.
• ECG monitoring and seizure management are crucial.

Beta-Blocker Overdose

• Beta-blockers slow down heart rate by blocking adrenaline hormones.
• Common uses include treating high blood pressure.
• Overdose leads to bradycardia, heart block, and hypotension
• Beta-blocker overdoses can result in severe delirium, seizures, and coma.
• Symptoms typically appear within 6 hours of ingestion.

Delirium

• Is an acute disturbance of the mind, marked by a sudden onset and diverse causes.
• Symptoms such as euphoria, confusion, hallucinations, restlessness, agitation, lethargy, and irritability or anger are possible.
• Causes include underlying illness, metabolic problems, medications, infections, alcohol or drug use/withdrawal.

Beta-Blocker Overdose Management

• Focus on restoring tissue perfusion using atropine and IV fluids.
• Atropine alone often insufficient; other causes need to be addressed.
• Atropine dosage varies by age; consult local guidelines.
• Sodium chloride (IV fluids) may be required and maximum dose should also be based on patient's age and conditions

Toxins (Organophosphates/Nerve Agents)

• Organophosphates are found in insecticides and fertilizers (and can be altered for use as nerve agents).
• Exposure can occur through inhalation, ingestion, or skin absorption.
• These toxins inhibit the enzyme acetylcholinesterase, affecting acetylcholine breakdown, causing an overstimulation of the parasympathetic and sympathetic nervous systems.
• Symptoms (muscarinic effects) include diarrhea, urination, miosis, bradycardia, bronchospasm, and vomiting; other symptoms (nicotinic effects) include mydriasis, tachycardia, weakness, hypertension, and fasciculations.
• Overdoses cause symptoms within minutes and the most dangerous symptoms include excessive respiratory secretions (bronchorrhea), bronchospasm, and respiratory insufficiency.
• Proper patient assessment (airway and breathing) is crucial for treatment, along with atropine given as an adjunct to oxygen. Atropine dosage varies by age; see local guidelines.
• DuoDote auto-injector (atropine combined with pralidoxime) is available for rapid administration. Protective personal equipment (PPE) should be used for protection.

Paraquat Poisoning

• Paraquat is a toxic herbicide, primarily found in liquid form, used in weed and grass control.
• Ingesting larger amounts primarily affects the lungs, liver, and kidneys.
• Symptoms include gastrointestinal issues (nausea, vomiting), dehydration, hypotension.
• Management includes considering activated charcoal if ingestion is recent.
• Supplemental oxygen may be unnecessary unless there are signs of hypoxia.

Medications Review (Next Week's Class)

• GTN, Morphine, Clopidogrel are listed for review next week.