Vagus nerve stimulation regulates hemostasis in swine

The central nervous system regulates peripheral immune responses via the vagus nerve, the primary neural component of the cholinergic anti-inflammatory pathway. Electrical stimulation of the vagus nerve suppresses proinflammatory cytokine release in response to endotoxin, I/R injury, and hypovolemic shock and protects against lethal hypotension. To determine the effect of vagus nerve stimulation on coagulation pathways, anesthetized pigs were subjected to partial ear resection before and after electrical vagus nerve stimulation. We observed that electrical vagus nerve stimulation significantly decreased bleeding time (pre-electrical vagus nerve stimulation = 1033 +/- 210 s versus post-electrical vagus nerve stimulation = 585 +/- 111 s; P < 0.05) and total blood loss (pre-electrical vagus nerve stimulation = 48.4 +/- 6.8 mL versus post-electrical vagus nerve stimulation = 26.3 +/- 6.7 mL; P < 0.05). Reduced bleeding time after vagus nerve stimulation was independent of changes in heart rate or blood pressure and correlated with increased thrombin/antithrombin III complex generation in shed blood. These data indicate that electrical stimulation of the vagus nerve attenuates peripheral hemorrhage in a porcine model of soft tissue injury and that this protective effect is associated with increased coagulation factor activity.