Hemorrhagic Shock Models in Swine
Swine have long been used as models for the study of hemorrhagic shock. In recent years there has been a resurgence of interest in the pathogenesis and treatment of hemorrhagic shock due to the ongoing conflicts associated with combating terrorism. Hemorrhage associated with trauma is a complex issue in humans because of the usual multiple system injuries that accompany it. This manuscript will discuss hemorrhagic shock as a primary issue and trauma models will be addressed in a separate manuscript.
Hemorrhagic shock leads to decreased cardiac output, stroke volume, and increased heart rate. These decreases lead to the reduced tissue perfusion that will result in multiple organ failure over time at fatal hemorrhage levels. Complete reviews of the effects of various hemorrhagic shock models on physiologic function have been published.Complete physiologic parameters of the various pigs used for these types of studies have been published. These values may vary considerably between breeds and ages of pigs within the same breed. For example the circulating blood volume ranges from 58.1-73.9 ml/kg. It is best to calculate the baseline values for the pigs used in the study at the time they are entered into the protocol.
M. Michael Swindle, DVM, Professor and Chairman, Department of Comparative Medicine, Medical University of SC, Charleston, SC 29425