Splanchnic blood flow and oxygen consumption: effects of enteral nutrition and dopexamine in the elderly cardiac surgery patient.

Background: After cardiac surgery, patients are at risk of organ dysfunction because of decreased perfusion. Different measures have been used to increase the splanchnic blood flow. We compared the effects of enteral nutrition and dopexamine on the cardiac output, splanchnic blood flow and oxygen consumption.

Methods: Sixteen patients undergoing cardiac surgery were included. Indocyanine green extraction and thermodilution were used for repeated measurements of the splanchnic blood flow and cardiac output. On the first post-operative day, indocyanine green infusion was started. Patients were randomized to start with dopexamine (Dpx group) or enteral nutrition (EN group). After 180 min, both groups received a combination of dopexamine and enteral nutrition. Blood gases from the hepatic vein and pulmonary and radial arteries were analysed repeatedly.

Results: In the Dpx group, the cardiac index increased with dopexamine infusion, but not when enteral nutrition was added. In the EN group, enteral nutrition alone did not increase the cardiac index, but dopexamine addition increased the cardiac index in this group. The splanchnic blood flow increased initially in the Dpx group, but then returned to baseline and remained constant on addition of enteral nutrition. In the EN group, the splanchnic blood flow initially remained at baseline, but increased after dopexamine addition. There was no difference between the groups with regard to systemic or splanchnic oxygen consumption or the oxygen extraction ratio. In the Dpx group, lactate increased from baseline with no further increase on addition of enteral nutrition. Lactate was unchanged in the EN group.

Conclusions: Dopexamine and enteral nutrition caused no adverse effects on oxygen consumption or the oxygen extraction ratio. Enteral nutrition did not increase the splanchnic blood flow or cardiac index. Dopexamine increased the systemic blood flow with only a transient effect on the splanchnic blood flow. Dopexamine increased the lactate concentration, possibly indicating a more ischaemic condition.