Vasopressin treatment in hemorrhagic shock

Computer-assisted intravital microscopy (CAIM) was used to study the real-time post-vasopressin microvascular changes in a canine hemorrhagic shock model. The bulbar conjunctiva was used as a readily accessible non-invasive microvascular site in this study. Vasopressin was infused (n=6) as an IV loading bolus followed by a 1-hr infusion. Dogs receiving an equal volume of saline served as controls (n=3). Within minutes after vasopressin treatment, significant (P<0.05) decreases in venular diameter and extensive vasoconstriction resulted, leading to a cessation of blood flow in most (>95%) conjunctival vessels. Post-vasopressin tissue oxygenation values decreased significantly (P<0.05), correlating with the changes in venular diameter and red-cell velocity. There was no significant post-vasopressin improvement in CO.