The effects of soman poisoning in combination with hypovolemic shock

Hemorrhage is a cause of death in both combat and civilian injuries. The specific objectives of this research were: (1) to determine the pathophysiologic effects of combined injuries from sublethal amounts of an organophosphate (soman) along with hypovolemic shock, and (2) to determine the efficacy of atropine sulfate and pralidoxime (2-PAM) therapy for organophosphate poisoning when combined injuries occur. Four groups of six beagle dogs/group were used: Group V/H, vehicle administration followed by hemorrhage; Group S/H, soman administration followed by hemorrhage; Group S/A/H, soman followed by antidote (atropine and 2-PAM) and then hemorrhage; and Group S, soman only. Acetylcholinesterase (AChE) activity, hemodynamic parameters, regional blood flow, plasma enzyme, and hematological changes were monitored. Soman rapidly decreased AChE activity in RBCs, plasma, and brain tissue. Treatment with atropine and 2-PAM resulted in only slight reactivation of AChE; they helped maintain blood gases, cortisol, plasma enzymes, inspiratory volume, and blood pressure nearer baseline values. The effects of combined injuries appear to be greater than those of either injury alone. This was indicated by increased plasma lactate, plasma enzymes indicative of tissue damage (aspartate amine transferase and creatine kinase), and increased lethality in dogs subjected to both soman and hemorrhage (5/12 died). All dogs subjected to only one insult survived the 6-hr experiment.