Vagotomy alters the hemodynamic response of dogs in hemorrhagic shock

We examined the hemodynamic response of severely hemorrhaged dogs to vagotomy to further define the role of vagal innervation in circulatory control during severe hemorrhage. When the cervical vagi were severed in severely hemorrhaged, pentobarbital-anesthetized dogs, MAP decreased immediately after vagotomy and remained lower than in vagal-intact dogs. Cardiac output (CO) and heart rate (HR) also remained lower in the vagotomized dogs. When 45 ml/kg of 0.9% NaCl was administered to vagal-intact or vagotomized, severely hemorrhaged dogs, the MAP and CO increases were attenuated by vagotomy. Blood flow increases in the renal and splanchnic, but not femoral, vascular beds were inhibited by vagotomy. Vagotomy attenuates the hemodynamic response of severely hemorrhaged dogs, limits the effectiveness of isotonic fluid therapy, and exerts a differential effect on blood flow distribution.