Mospel (Organophosphate) Poisoning - Management

Mechanism of Toxicity

Clinical Presentation - The Cholinergic Toxidrome

• Salivation
• Lacrimation
• Urination
• Diarrhea / Diaphoresis
• Gastrointestinal cramps
• Emesis

• Bradycardia
• Bronchorrhea
• Bronchospasm

The majority of severely poisoned patients will have altered mental status, pinpoint pupils, excessive sweating, and difficulty breathing.

Diagnosis

• Clinical - based on history + cholinergic toxidrome. Do not delay treatment while awaiting labs.
• Plasma butyrylcholinesterase - easier to assay, decreases first; may be reduced up to 50% in asymptomatic patients
• Red cell acetylcholinesterase - more accurate indicator; reduced to 10-20% of normal in moderate poisoning, <10% in severe
• ECG: QTc prolongation, ST changes, torsades de pointes, AV block
• CXR: Pulmonary edema in severe cases
• Bloods: Pancreatitis, hypo/hyperglycemia, leukocytosis, abnormal LFTs possible

Management - Four Goals

1. Decontamination
2. Supportive care with respiratory stabilization
3. Reversal of acetylcholine excess (antidotes)
4. Reversal of toxin binding at cholinesterase

Step 1: Scene Safety & Decontamination

• PPE for staff: Level C protection - full-face air purifier mask, eye shield, chemical-resistant suit, nitrile/butyl rubber gloves (NOT latex)
• Remove all clothing - place in plastic bags and treat as hazardous waste
• Wash skin thoroughly with copious water and mild detergent (soap/dishwashing liquid); include scalp, hair, fingernails, skin folds, conjunctivae
• Eye exposure: Flush with water for at least 15 minutes
• Inhalation: Remove to fresh air immediately
• Ingestion: Gastric lavage and activated charcoal have no proven benefit - vomiting/diarrhea already flush GI tract; rapid absorption negates benefit
• Contain and dispose of runoff water as hazardous material

Step 2: Airway & Supportive Care

• 100% oxygen via non-rebreather mask - optimize oxygenation before atropine to minimize dysrhythmia risk
• Intubation if: coma, seizures, respiratory failure, severe bronchospasm/bronchorrhea
  • Preferred paralytic: Rocuronium 1 mg/kg (non-depolarizing, not metabolized by cholinesterases)
  • Avoid succinylcholine if possible - metabolized by cholinesterases; in OP poisoning, duration may extend to 4-6 hours
• Suction airway secretions aggressively
• Cardiac monitoring + pulse oximetry + ECG
• IV access with baseline bloods including cholinesterase levels
• Avoid beta-blockers for tachycardia - treat the underlying cholinergic excess instead

Step 3: Antidote Therapy

A. Atropine (Muscarinic Antagonist) - FIRST-LINE

• Dry chest on auscultation (secretions cleared)
• Heart rate >80 bpm
• Systolic BP >80 mmHg
• Respiratory rate normalizing

Note: Atropine requirements can exhaust hospital supplies. Alternative anticholinergics if atropine unavailable: IV glycopyrrolate (does not cross BBB - no CNS effect) or nebulized ipratropium bromide for pulmonary muscarinic effects.

B. Pralidoxime / 2-PAM (Oxime - Cholinesterase Reactivator) - SECOND-LINE

Pralidoxime is most effective when given early. Once "aging" of the OP-AChE bond occurs (varies by compound), it is no longer effective. Aging for most agricultural OP compounds occurs over hours to days; nerve agents like soman age within minutes.

C. Benzodiazepines (for Seizures)

• Diazepam 5-10 mg IV (repeat as needed) - first-line for seizures
• Other benzodiazepines (lorazepam, midazolam) are also appropriate
• Benzodiazepines should be given after airway is secured

Step 4: Manage Complications

Step 5: Enhanced Elimination

• No role for hemodialysis or other extracorporeal elimination techniques.

Intermediate Syndrome

• Proximal limb weakness, neck flexor weakness
• Respiratory muscle paralysis (can cause respiratory failure)
• Cranial nerve palsies
• Managed with respiratory support; usually resolves within 7 days

Delayed Neuropathy (Organophosphate-Induced Delayed Neuropathy - OPIDN)

• Appears weeks after exposure
• Symmetrical sensorimotor axonopathy - leg cramps, weakness, can mimic Guillain-Barré syndrome
• Cognitive dysfunction, autonomic dysfunction, peripheral neuropathy, extrapyramidal signs
• No specific antidote; supportive management

Disposition

• All symptomatic patients require hospital admission for monitoring and treatment
• Severe cases require ICU-level care
• Asymptomatic patients with confirmed significant exposure should be observed for at least 6-8 hours

Summary Algorithm

MOSPEL (OP) POISONING
│
├── SCENE SAFETY → PPE for all staff
├── DECONTAMINATION → Remove clothes, wash skin with soap & water
│
├── AIRWAY → O2, intubate if needed (use rocuronium, not succinylcholine)
├── MONITORING → Cardiac monitor, SpO2, ECG, IV access
│
├── ANTIDOTES:
│   ├── ATROPINE → 1.2-3 mg IV, double q5min → atropinize → then infusion 10-20%/hr
│   ├── PRALIDOXIME → 30 mg/kg IV over 5-10 min → 8 mg/kg/hr x 24-48h
│   └── BENZODIAZEPINES → Diazepam 5-10 mg IV for seizures
│
└── COMPLICATIONS → Treat seizures, arrhythmias, rhabdomyolysis, hyperthermia

• Rosen's Emergency Medicine: Concepts and Clinical Practice, Chapter 152
• Tintinalli's Emergency Medicine: A Comprehensive Study Guide, Chapter 201
• Morgan & Mikhail's Clinical Anesthesiology, 7e
• Lippincott Illustrated Reviews: Pharmacology