Introduction
Organophosphate poisoning is a critical toxicological emergency that may be encountered in both prehospital and hospital settings. Exposure can occur through accidental contact, occupational exposure, or intentional ingestion. These substances are commonly found in many insecticides used in agricultural and household environments.
Facts
Organophosphates are widely used chemical agents in pest control products. Examples of related compounds and products include:
- Acephate (Orthene)
- Diazinon (Basin, Knox Out, Spectracide)
- Malathion (Celthion, Python)
- Carbamates (organophosphate-like compounds)
- Pyrethrins/pyrethroids (found in products such as Raid)
- Warfarin (included in some toxic exposure discussions due to similar poisoning contexts)
Carbamates were developed as alternatives to organophosphates and are also associated with a significant number of poisoning cases, with a notable portion requiring hospitalization.
Mortality rates vary depending on age and exposure severity:
- Adults: approximately 10%
- Pediatrics: up to 50% in severe cases
These compounds may also have structural similarities to agents used in chemical warfare.
Common exposure routes include:
- Intentional ingestion (often in suicide attempts)
- Accidental exposure in agricultural settings
- Occupational exposure during manufacturing or handling
Pathophysiology
Organophosphates affect the autonomic nervous system by disrupting normal neurotransmission at synapses. Acetylcholine is a neurotransmitter responsible for transmitting nerve impulses between cells. Under normal conditions, acetylcholine is broken down by the enzyme acetylcholinesterase into acetate and choline after it has completed its signaling role.
Organophosphates inhibit acetylcholinesterase through phosphorylation of the enzyme, rendering it inactive. As a result, acetylcholine accumulates in synapses and continues to overstimulate nerve receptors. This excessive stimulation leads to continuous activation of both muscarinic and nicotinic receptors, disrupting normal nervous system function.
Signs and Symptoms
Symptoms typically develop within minutes to hours (often within the first 8 hours) following exposure and may include:
Neurologic and CNS Effects
- Anxiety and restlessness
- Headache and dizziness
- Confusion
- Tremors
- Seizures
- Loss of consciousness
Respiratory Effects
- Dyspnea
- Wheezing
- Respiratory depression or failure
Cholinergic Toxicity (SLUDGE/DUMBELS-type symptoms)
- Salivation
- Lacrimation (tear production)
- Urination
- Defecation or diarrhea
- Gastrointestinal cramping
- Emesis (vomiting)
Assessment and Management
Decontamination
Immediate decontamination is essential before transport or extensive patient contact:
- Remove all contaminated clothing
- Place contaminated materials in sealed plastic bags for hazardous waste handling
- Wash patient thoroughly with soap and water when possible
Airway and Breathing
- Establish and maintain a patent airway
- Prepare for advanced airway management if needed
- Suction airway secretions due to excessive salivation or vomiting
- Provide oxygen to maintain SpO₂ ≥ 95%
- Monitor EtCO₂ and oxygen saturation closely
Circulation
- Continuous cardiac monitoring (4-lead ECG)
- Watch for bradycardia and dysrhythmias
- Establish IV access for medication and fluid administration
Medications (follow local protocols)
- Atropine: 0.1 mg IV push repeated every 3–5 minutes until symptoms improve
- Pralidoxime (2-PAM): 1–2 g IV infusion over 5–10 minutes with normal saline
Transport and Notification
Rapid transport to an appropriate medical facility is essential. Early notification to the receiving hospital is critical so that antidotes, decontamination resources, and intensive care support can be prepared in advance.
Organophosphate poisoning is a true time-sensitive emergency, and early recognition, decontamination, and antidotal therapy significantly improve patient outcomes.