CURRENT Essentials of Critical Care.pdf

238 Current Essentials of Critical Care■■■Organophosphate PoisoningEssentials of Diagnosis• Peripheral muscarinic effects: salivation, lacrimation, urinary incontinence,diarrhea, (SLUD syndrome); bronchospasm, bronchorrhea,nausea, vomiting, miosis, blurred vision, diaphoresis• Peripheral nicotinic effects: muscle fasciculations, weakness,ataxia, paralysis.• CNS effects: headache, slurred speech, confusion, seizures,coma, depressed ventilatory drive• Death from respiratory center depression, respiratory muscleweakness, bronchospasm, and bronchial secretions• Found in insecticides and herbicides; exposure due to dermalexposure or ingestion; inactivation of acetylcholinesterases withexcessive stimulation of cholinergic receptors• No definitive laboratory test available; diagnosis based on clinicalsyndrome and response to therapy; cholinesterase activitylevel can be obtained, but may take days for resultsDifferential Diagnosis• Myasthenia gravis with cholinergic crisisTreatment• Irrigate areas of dermal exposure copiously• Gastric lavage if ingestion within one hour, followed by activatedcharcoal• Intubation and ventilatory support should be considered early• Atropine to reverse peripheral muscarinic effects; does not reverseskeletal nicotinic effects• Atropine for diagnostic testing: 1 mg IV; watch for papillary dilatationand increase in heart rate; if no response, cholinergictoxicity suggested• Atropine for treatment: 2–4 mg intravenously every 10–15 minutesuntil drying of secretions• Pralidoxime reverses nicotinic muscle effects; give with atropinein dose of 25–50 mg/kg over 5–15 minutes; observe for increasedmuscle strength; can repeat every 4–12 hours as needed■ PearlChemical weapons known as nerve agents are a very toxic group oforganophosphates; these should be considered in a chemical attack.ReferenceLeikin JB et al: A review of nerve agent exposure for the critical care physician.Crit Care Med 2002;30:2346. [PMID: 12394966]