Cholinesterases sarin poisoning

Sarin poisoning is associated with a marked decrease in plasma cholinesterase. In the Mat-sumoto sarin attack, Okudera (2002) documented that mean standard values (midpoint of the upper and lower levels) for plasma cholinesterase levels and the mean pupil diameters were < 50% and 0.9 mm in severe cases, 50-100% and 1.3 mm in moderate cases, and > 100% and 2.2 mm in mild cases, respectively. 

At the same time, doctors and nurses from the Self Defense Force Central Hospital also suspected sarin poisoning and brought various documents and supplies to St. Luke s International Hospital. By the time most of the patients with cardiopulmonary or respiratory arrest had been resuscitated, results of laboratory tests revealed decreased plasma cholinesterase. Based on the various medical data, clinical and test findings, sarin poisoning was diagnosed with relative ease. 

Given the earlier Matsumoto sarin attack experience, sarin poisoning was diagnosed relatively smoothly based on the symptoms and laboratory findings (particularly assays of plasma cholinesterase). 

Organophosphate and carbamate cholinesterase inhibitors (see Chapter 7) are widely used to kill insects and other pests. Most cases of serious organophosphate or carbamate poisoning result from intentional ingestion by a suicidal person, but poisoning has also occurred at work (pesticide application or packaging) or, rarely, as a result of food contamination or terrorist attack (eg, release of the chemical warfare nerve agent sarin in the Tokyo subway system in 1995). 

A special issue from this Japanese experience are ocular effects of poisoning with sarin and their treatment. Some authors unsuccessfully treated strong miosis and consequential visual darkness with systemic atropine [15, 29], Others used 0.25% or 1.0% atropine sulphate eye drops, but these patients complained of atropine-induced photophobia and poor focusing [25], Our suggestion for optimal treatment of ocular manifestations of intoxication with organophosphorus cholinesterase inhibitors is topical use of pralidoxime chloride eye drops instead of atropine [42], Ocular pain should be treated with tropicamide 0.5% [28],... 

PHBA (11), which can cross the blood-brain barrier, has been proposed as a reactivator of phosphorylated cholinesterases for the treatment of poisoning due to organophosphates (sarin, soman, etc.) [67]. This quality was known before PHBA was detected in a marine fungus. 

Organophosphorus compounds and carbamates, also known more generally as cholinesterase inhibitors, are widely used pesticides that may cause poisonings after accidentai or suicidal exposure. Poisonings are particularly common in rural areas and third-world countries where more potent agents are widely available. Several chemical warfare agents (eg, GA [Tabun], GB [Sarin], GD [Soman], GF, and VX) are extremely potent cholinesterase inhibitors (see p 372 and Table 11-57). Household insect sprays often contain low-potency cholinesterase inhibitors. (Many commercial products also contain solvents such as toluene or xylene that can themselves produce toxic effects in an overdose see p 357). 

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