These compounds are divided into the militarized agents GA (tabun), GB (sarin), GD (soman), and VX and the nonmilitarized or agricultural agents parathion, malathion, diazinon, and many other derivatives. The latter are considered less potent, but with a large dose they can be formidable substances.21,22
Organophosphates are toxic by all routes of exposure. Regardless of the route of exposure, signs and symptoms are cholinergic in nature and will be muscarinic or nicotinic. Salivation, lacrimation, urination, defecation, gastrointestinal symptoms, and emesis form the acronym SLUDGE to assist in remembering the basic signs and symptoms. Pinpoint pupils, chest tightness, shortness of breath, excessive sweating, muscle twitching, confusion, seizures, paralysis, coma, respiratory paralysis, and death may also occur. With the more potent military agents, the incapacitating effects can occur within 1 minute and fatal effects can occur within 1 to 10 minutes. Fatigue, irritability, nervousness, and memory defects may persist for as long as 6 weeks after recovery from an exposure episode.21,23
As a result of the rapid onset of severe signs and symptoms, nerve agents are stored and shipped differently than other treatments found in the SNS. As previously stated, they are stored under CHEMPACK. CHEMPACK is a voluntary program of the SNS operated by the CDC for the benefit of the US civilian population. Its mission is to provide state and local governments a sustainable nerve agent antidote cache. The CHEMPACK only contains materials for a nerve agent exposure and does not contain any other materials.
In the event of an organophosphate (OP) poisoning, three agents need to be readily available (atropine, pralidoxime, and diazepam). Atropine will be used to counter the muscarinic effects commonly seen. However, it has little affinity for nicotinic receptors and will not reverse respiratory paralysis, fasciculation, or general muscle weakness.23 Pralidoxime will be used to reverse the binding of the OP to the acetylcholinesterase as long as aging has not occurred. Aging is the process by which the OP covalently binds the acetylcholinesterase rending it useless. Aging can occur in <12 hours with some of the militarized OPs, this is the principal reason for the CHEMPACK. Diazepam will be used to prevent or treat seizures.21,22,23
- Adult: 2 to 6 mg (0.02-0.04 mg/kg) repeated every 2 to 30 minutes.
- Pediatric: 0.05 to 0.1 mg/kg bolus every 2 to 30 minutes.
- Adult: 1 to 2 g in 100 mL of 0.9% NS, IV, over 15 to 30 minutes followed by a continuous infusion of 500 mg/h. The infusion should be continued until symptoms have resolved for at least 24 hours.
- Pediatric: 20 to 40 mg/kg in 100 mL of 0.9% NS over 30 minutes up to a maximum of 1 g followed by a continuous infusion of 10 to 20 mg/kg/h. The infusion should be continued until symptoms have resolved for at least 24 hours.
CNS damage from OP poisoning is currently thought to be due to seizure activity rather than a direct toxic effect. Prevention and treatment of seizures with diazepam is an important aspect of patient management. Seizures are more common in pediatric poisoning with cholinesterase inhibitors.21,22,23
- Adult: 5 to 10 mg, IV, every 5 to 10 minutes (one, 10-mg autoinjector, every 10 minutes − 3 maximum)
- Pediatric: 0.2 mg/kg, IV, every 5 to 10 minutes.
aDosing until someone has tachycardia, mydriasis, and dry membranes should be avoided. Clinically significant control is best described as a
decrease in bronchorrhea and bronchoconstriction with a corresponding increase in oxygenation and ventilation.21,22,23
aDosing until someone has tachycardia, mydriasis, and dry membranes should be avoided. Clinically significant control is best described as a decrease in bronchorrhea and bronchoconstriction with a corresponding increase in oxygenation and ventilation.21,22,23