Influence of enteral and parenteral nutrition on splanchnic hemodynamics in septic patients.

BACKGROUND

Enteral nutrition is believed to augment splanchnic perfusion, thereby preserving splanchnic integrity, whereas parenteral nutrition does not offer this benefit. In an effort to study this, we compared splanchnic oxygen exchange and blood flow in critically ill, septic patients to normal controls during enteral or total parenteral nutrition.

METHODS

Splanchnic oxygen exchange and hepatic blood flow characteristics in 14 critically ill, septic patients were compared to 19 normal controls while fasting and during nutrient administration. Nutrients were delivered as intraduodenal feedings or parenteral nutrition. Splanchnic hemodynamics were measured at baseline, 90 min, and 210 min during nutrient administration. Hepatic blood flow index (HBFI) by indocyanine green dye (ICG) clearance, splanchnic oxygen consumption index (SplVO(2)I), and hepatic venous oxygen saturation (ShvO(2)) were measured using hepatic venous catheterization. Plasma volume (PV) was measured from the volume of ICG distribution. Results were analyzed using population means (+/-SD) and one-way analysis of variance.

RESULTS

There was no statistical change in HBFI, SplVO(2)I, PV or ShvO(2) over the study time interval within any group (p < 0.05), irrespective of whether enteral or parenteral nutrition was the nutrient source. Septic patients, whether fasting or receiving nutrition, demonstrated higher HBFI and SplVO(2)I levels, whereas ShvO(2) levels were uniformly lower throughout the study compared to normal controls.

CONCLUSIONS

Critically ill patients exhibited a hyperdynamic splanchnic state as indicated by the marked increase in HBFI and SplVO(2)I. However, neither nutrient regimen at clinically relevant rates altered splanchnic hemodynamics over the course of study. Thus, enteral nutrients do not appear to offer hemodynamic protection to the splanchnic system in critically ill patients.