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 (SplVO2I), and hepatic venous oxygen saturation
(ShvO2) 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, SplVO2I, PV or ShvO2 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 SplVO2I levels, whereas ShvO2 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 SplVO2I. 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.
