CHOLINESTERASE ACTIVITY IN POSTMORTEM BLOOD AS A SCREENING-TEST FOR ORGANOPHOSPHATE CHEMICAL WEAPON EXPOSURE

This study was undertaken to determine whether postmortem blood cholin sterase activity could be used as a screening test for exposure to ner ve agents. Whole blood cholinesterase activity at 25-degrees-C was ana lyzed for a one week period in order to simulate the battle field coll ection problems of: hemolyzed blood samples, delayed recovery of the s pecimen, and unrefrigerated transfer to the testing facility. A total of 53 nonpreserved postmortem whole blood specimens were analyzed in t riplicate for cholinesterase activity by the DELTA pH method of Michel . There was a negligible loss of cholinesterase activity by the sevent h day of the study. The enzyme activities of the specimens had a mean value (range) of 0.48 (0.20 to 0.74) initially and 0.45 (0.07 to 0.70) pH units after one week. Whole blood from five healthy adults remaine d essentially unchanged during this period, with an initial value 0.59 (0.52 to 0.67) and a final value of 0.52 (0.46 to 0.62) pH units. To compare postmortem and simulated nerve agent values, aliquots from 18 of the original 53 postmortem specimens were frozen during day one of the study, thawed on day seven and a cholinesterase inhibitor added. T hese specimens were then analyzed with the other specimens. All values from inhibited specimens were essentially zero (0.0 to 0.01) pH units compared to a range of 0.07 to 0.61 pH units for matched. uninhibited , day seven postmortem specimens. Fifteen actual nonpreserved specimen s from the battlefield were analyzed as verification of screen perform ance. Their results fell within the uninhibited postmortem range above . All of the 53 day one postmortem, day seven postmortem, and 13 of 15 battlefield specimen cholinesterase activities were significantly gre ater than the levels found in the 18 specimens exposed to the cholines terase inhibitor. We conclude that the cholinesterase activity in post mortem specimens collected within a one week period of death can be us ed as a screen for possible nerve agent exposure.