Anticholinesterase Poisoning

Anticholinesterase Poisoning General Information

Anticholinesterase is the general name given to a substance that acts by inhibiting the action of the cholinesterase enzyme. This enzyme is used by the body to destroy a neurotransmitter, namely acetylcholine, which has the role of transmitting certain impulses within the parasympathetic nervous system – the secretion regulating impulses, those coordinating the contractions of the smooth muscles and the dilation of the blood vessels. As the enzyme is inhibited, the acetylcholine accumulates in large quantities and continuously stimulates the parasympathetic nervous system, leading to contractions of the smooth muscles, increased secretion, low blood pressure and a general slowing down of the heart.

Anticholinesterase Poisoning results from a large quantity of such substances entering the body by inhalation, ingestion or skin or eye contact. While these substances are present in nature, under the form of venom from certain species, they are mainly encountered in human activity, as their high effectiveness caused them to be largely employed as pesticides (substances such as Parathion or Malathion are very common agricultural insecticides, for example) and even as chemical weapons (under the form of nerve gases: tabun, sarin and soman, to name a few). As a result, Anticholinesterase Poisoning is mostly encountered in areas of the human activity that deal with these substances on a regularly basis.

There are some medical uses for such substances, however they are not common. They are employed in the treatment of such affections as obstructions of the intestines, myasthenia gravis or Alzheimer’s disease, and also as an antidote to some cases of poisoning (mainly in cases of anticholinergic poisoning).

Anticholinesterase Poisoning Symptoms

Anticholinesterase Poisoning is caused by the substances entering the body either by ingestion, inhalation, or skin contact. Currently, most cases of poisoning are caused by accidental exposure to pesticides, either by applying the substance while farm workers are still in the field, or by re-entering exposed areas before the safety levels drop back to normal, as well as accidents manufacturing or transporting the substances. There have been cases of poisoning by coming in contact with people that have been exposed to the substance, thus secondary transmitted poisoning is possible.

Whether due to exposure to pesticides or to chemical weapons, Anticholinesterase Poisoning may have a quick and fatal effect or a long-term latent one, and of course there are several intermediary stages. The symptoms may vary depending on the type of poisoning, but generally such symptoms as drowsiness and disorientation, sweats, salivation, bradycardia, diarrhea, vomiting, nausea and bronchial obstruction are noted. The conditions may be mild to severe, and also may be accompanied by muscular twitching, cramps or even paralysis in the case of severe poisoning. Symptoms may also affect the heart, and in such cases tachycardia and a rise in blood pressure has been documented. Untreated poisoning will lead to coma and death.

Severe cases of Anticholinesterase Poisoning result in death due to cardiac arrest, as the muscles paralyze and the nervous impulses are blocked, while the bronchial secretions are stimulated and worsen the respiratory failure. Death is preceded by seizures and a loss of consciousness. Even if the poisoning is treated in time, it can cause long term neural damage leading to further disorders and affections.

Anticholinesterase Poisoning Treatment

First and foremost, in cases of Anticholinesterase Poisoning it is highly advised that the patient is only treated by qualified health care specialists. Immediately contact the local Poisons Center and the emergency medical service, and proceed with decontamination of the victim, after ensuring that you are protected from accidental contamination. Also you need to ensure that the victim’s breathing is not impaired in any way – however mouth-to-mouth or mouth-to-nose artificial breathing is not advised.

As in most cases of poisoning, the primary measure that needs to be taken when suspecting Anticholinesterase Poisoning is to remove the patient from the exposed environment and to thoroughly wash any body part that may have come in contact with the substance. Contaminated clothes must be removed and will need to be laundered before being reused. Any leather items must be discarded as they are no longer suitable to wear. If ingestion is suspected, gastric lavage should be employed, in an attempt to remove any quantity of the substance that may be present. It is very important that the decontamination is performed immediately and thoroughly, ensuring that the victim is no longer exposed to any remains of the hazardous substance.

Anticholinesterase Poisoning victims should be treated only by dedicated health care personnel, as there is a high risk of the contamination being transmitted to secondary victims. Furthermore, the health care specialists should always use proper skin and respiratory protection when treating such cases, and while the decontamination is performed the next steps for the treatment should be set up, as time can be invaluable in saving the patient’s life. At all times, the respiratory tract must be maintained and protected, supplementary oxygen provided if necessary.

After the decontamination is complete medication treatment for the Anticholinesterase Poisoning can be employed. Typically this consists of atropine administered doses of 2 to 5 mg IV every 15 minutes, in order to suppress some of the most dangerous symptoms, coupled with Pralidoxime or Obidoxime, general cholinesterase reactivators, in moderate doses as in some cases these may cause muscular blocking by partially inhibiting cholinesterase. A dosage of 1 to 2 g over 10 minutes, repeated after 1 – 2 hours and again at intervals of 10 to 12 hours should be sufficient, or alternatively this drug can be administered via continuous IV infusion of 10-20 mg/kg/hr over 24 hours. Supplementary medication for pulmonary symptoms control can be employed, such as Furosemide IV in doses of 40 to 160 mg. In case of seizures, benzodiazepines can be administered to control the symptoms – an effective example is diazepam (Valium) in 5-10 mg doses, slowly injected IV and repeated every 5-10 minutes. Anticholinesterase Poisoning can be prevented by proper safety training of the people that can come in contact with the substances. Most of the time, such cases come as a result to insufficient information regarding handling and exposure to the substances and with proper training they could be avoided.