Toxicology: A Paramedic Study Guide

Structured Management of the Poisoned Patient

Safe & Effective Basic Life Support (BLS)

Poisoning incidents require a heightened awareness of scene safety and specific modifications to standard BLS to protect both the patient and the practitioner.

Danger & Decontamination: Always assume the toxin is still present. Ensure adequate ventilation in confined spaces (e.g., carbon monoxide, chemical fumes). If cutaneous exposure is suspected, perform gross decontamination (remove clothing, dry brush powders, irrigate liquids) prior to transport to prevent secondary contamination of the ambulance.
Airway Protection: Poisoned patients have a high risk of vomiting and reduced GCS. Prioritize lateral positioning (recovery position) early if the patient is unconscious to prevent aspiration of toxic gastric contents.
Breathing: Monitor for hypoventilation (opioids/sedatives) or hyperventilation (salicylates attempting to blow off acid). Provide positive pressure ventilation via BVM if respiratory drive fails.
Circulation: Initiate chest compressions if required, but avoid mouth-to-mouth resuscitation (use a BVM with a viral filter) to prevent provider exposure to the toxin.

The Structured Assessment Approach

While the exact toxin may be unknown, a systematic approach ensures life threats are caught early. We treat the patient, not just the poison.

Resuscitation (ABCDE): Address immediate life threats. Support airway, ventilation, and perfusion.
Risk Assessment: Gather history. What was taken? How much? When? Route? Intentional or accidental? Co-ingestions? Bring containers/pill bottles to the hospital.
Supportive Care & Monitoring: Continuous ECG, SpO2, EtCO2, Blood Glucose (crucial to rule out hypoglycemia as a cause of AMS), and temperature monitoring.
Specific Antidotes / Investigations: e.g., Naloxone for opioids, Midazolam for toxin-induced seizures. Contact the Poisons Information Centre (13 11 26) early for expert toxicologist advice.

The 4 Common Toxidromes

A toxidrome (toxic syndrome) is a constellation of clinical signs and symptoms that suggest a specific class of poisoning. Recognizing these patterns guides empiric treatment when the exact agent is unknown.

Table: Recognition of Toxidromes

Based on Cameron et al., 'Textbook of Paediatric Emergency Medicine'

Toxidrome	Agents Associated	Clinical Features
Anticholinergic	Antihistamines Tricyclic antidepressants (TCAs) Antipsychotics Atropine Carbamazepine Anticholinergic plants (e.g., Datura)	Agitated delirium / Sedation Mydriasis (dilated pupils) Tachycardia Dry mouth and skin Hyperthermia Ileus (reduced bowel sounds) Urinary retention
Cholinergic	Organophosphate pesticides Carbamate insecticides Chemical warfare nerve agents Dementia drugs (e.g., donepezil) Myasthenia drugs (e.g., neostigmine)	Agitation, coma, seizures Muscle fasciculation, weakness, paralysis Salivation, lacrimation, diaphoresis Bronchorrhoea (excessive airway secretions - usually the cause of death), vomiting, diarrhoea Miosis (pinpoint pupils) Bradycardia or tachycardia
Serotonin Syndrome	SSRIs / SNRIs MAOIs St John's wort Tramadol TCAs Amphetamines	Mental status changes: anxiety, agitation, confusion Autonomic stimulation: hyperthermia, tachycardia, hypertension, mydriasis Neuromuscular excitation: increased tone (lower limbs > upper limbs), hyperreflexia, clonus, tremor, rigidity
Sympathomimetic	Catecholamines Amphetamines Cocaine Xanthines (e.g., theophylline, caffeine) MAOIs Noradrenaline reuptake inhibitors (e.g., venlafaxine)	Tachycardia / Hypertension Hypotension (in severe, late cases) Hyperthermia Agitation, delirium, seizures, coma Mydriasis (dilated pupils) Metabolic acidosis

Paediatric Considerations in Poisoning

How Does Paediatric Management Differ?

While the fundamental requirement to save a life remains the same, the execution differs dramatically in paediatrics due to anatomy, physiology, and pharmacology.

Pharmacokinetics & Susceptibility: Children have a larger surface-area-to-mass ratio, faster metabolisms, and immature hepatic/renal clearance pathways. A dose that is harmless to an adult (e.g., "One pill can kill" concept with calcium channel blockers or sulfonylureas) can be lethal to a toddler.
Weight-Based Management: All fluid resuscitation, antidote dosing (e.g., Naloxone, Midazolam), and equipment sizes (BVM, airways) must be strictly calculated based on the child's weight, requiring cognitive offloading tools like Broselow tapes or pediatric reference cards.
Baseline Vital Signs: Normal physiological parameters vary drastically by age. Recognizing tachycardia or hypotension requires age-specific knowledge. Children compensate well but decompensate rapidly.

Does the Systematic Approach Apply?

Yes. The systematic approach (Danger, Response, ABCDE) applies universally. However, the threshold for intervention is lower in paediatrics. For example, aggressive airway management and oxygenation are prioritized because the primary cause of cardiac arrest in children is hypoxia (which can rapidly develop from central nervous system depression caused by a toxin), rather than a primary cardiac event.

Beyond Clinical Care: Professional Responsibilities

Epidemiology & Context of Paediatric Poisoning

Understanding why the poisoning happened dictates the broader approach to care. Paediatric poisonings generally fall into distinct epidemiological categories:

Toddlers (1-4 years): Usually accidental, exploratory ingestions. Driven by curiosity and inadequate safe-storage of household chemicals or grandparents' medications.
Adolescents (12-18 years): More likely to be intentional overdoses related to self-harm, mental health crises, or recreational substance abuse.
Infants/All Ages: Highly rarely, but critically, can be due to deliberate harm by a caregiver (e.g., Munchausen syndrome by proxy or malicious intent).

Other Domains of Care: The Psychosocial Element

When presented with a poisoned paediatric patient, clinical treatment is only one facet. Another critical domain of care is the Psychosocial and Environmental domain.

Family Support: Parents will likely be in extreme distress, experiencing profound guilt (if accidental) or shock (if intentional self-harm). Effective, empathetic communication and family-centered care are essential to calm the scene and gather an accurate history.
Environmental Safety Assessment: Observing the living conditions. Are medications left out? Is the home environment safe? This informs future prevention.

Professional & Legal Responsibilities

As a registered health practitioner, you possess significant responsibilities outside of pure medical intervention:

Mandatory Reporting: If the poisoning appears to be the result of severe neglect, inadequate supervision, or intentional harm/abuse, paramedics have a legal and ethical duty to report these concerns to child protection services (e.g., FACS/DCJ) and police.
Mental Health Act / Risk Assessment: For adolescents who have intentionally overdosed, paramedics must conduct a mental health risk assessment. You have a duty of care to ensure they are transported for psychiatric evaluation, even if they refuse, utilizing relevant mental health legislation if they lack capacity.
Education & Prevention: Taking the opportunity (when appropriate) to educate parents gently on safe storage, the use of child-resistant containers, and providing the Poisons Information Centre contact details.
Thorough Documentation: In cases of suspected abuse or neglect, clinical records become vital legal documents. Documentation must be objective, factual, and detailed regarding the scene, the history provided, and the presentation of the child.