Dopexamine attenuates microvascular perfusion injury of the small bowel in pigs induced by extracorporeal circulation

Background. Cardio-thoracic surgery with the use of extracorporeal circulation may lead to an impairment of splanchnic perfusion. The aim of this study was to investigate the effect of dopexamine on gastrointestinal microvascular perfusion failure due to extracorporeal circulation. Methods. Twenty landrace pigs served as laboratory animals. A loop of the terminal ileum was exteriorized for microscopic observation. In 13 animals a partial left-heart bypass (pLHB), with a non-pulsatile pump flow of approximately 50% of the cardiac output, was established for 2 h. Seven animals received a continuous i.v. infusion of 3 mug kg(-1) min(-1) dopexamine from the beginning of pLHB to the end of the experiment. Seven sham-operated animals served as controls. The microcirculatory network was analysed by means of intra-vital microscopy prior to, during pLHB, and 2 h after bypass. Results. Despite normal haemodynamics measured by arterial pressure and cardiac output, pLHB led to significant impairment of microvascular perfusion characterized by arteriolar vasoconstriction, reduction of functional capillary density (FCD) to 30% 2 h after weaning off bypass and diminished blood-cell velocities in submucous venules. Dopexamine attenuated this perfusion impairment, preventing arteriolar vasoconstriction. FCD remained normal. Conclusion. Our data demonstrate that treatment with the vasoactive drug dopexamine leads to a significant reduction of the perfusion injury of the small bowel.