Vasopressor agents after experimental brain death: effects of dopamine and vasopressin on vitality of the small gut.

Background: Both congenital and acquired short bowel syndrome frequently leads to the necessity for long-term parenteral nutrition, which in turn may lead to any of several complications or death. Transplantation of the small bowel from brain-dead organ donors has been successfully performed over the last years. However, systemic blood pressure and blood perfusion to the splanchnic area decrease rapidly after brain death, which comprises the vitality of the small bowel.

Objective: To evaluate the differences between dopamine and low-dose vasopressin on perfusion and vitality of the small bowel after brain death.

Methods: Fifteen pigs were randomized into 3 groups: vasopressin (n = 6), dopamine (n = 6), or control (n = 3). Brain death was induced via stepwise filling of an epidural balloon. When the hypotensive phase was achieved, vasopressin, maximum dose of 0.04 IU/kg/h, or dopamine, maximum dose of 20 μg/kg/min, was administered for 5 hours with the objective of increasing mean arterial blood pressure by 15 mm Hg.

Results: Target blood pressure was achieved in the vasopressin group but not the dopamine group. Vasopressin reduced cardiac output, superior mesenteric artery (SMA) blood flow and oxygen delivery, and systemic oxygen delivery and consumption, and increased oxygen extraction. Dopamine increased SMA blood flow, and had no effect on systemic oxygen delivery or consumption.

Conclusions: Vasopressin reversed hypotension but compromised both the systemic and SMA blood flow. Vasopressin was associated with inadequate oxygen delivery, estimated from decreased oxygen delivery and increased oxygen extraction. These adverse effects were not observed with dopamine.