ENTERAL FEEDING IMPROVES OUTCOME AND PROTECTS AGAINST GLYCEROL-INDUCED ACUTE-RENAL-FAILURE IN THE RAT

Acute renal failure is a common cause of morbidity and mortality in cr itically ill patients and frequently results from vasoconstrictive isc hemic injury to the kidney. Protein and amino acids can vasodilate ren al blood vessels. Thus, we tested the hypothesis that enteral feeding could prevent renal ischemic injury using an experimental model in whi ch renal vasoconstriction is believed to cause ischemic renal injury. This study was performed using male Sprague-Dawley rats, and renal inj ury was induced by glycerol injection into the hind limbs. The resulti ng muscle necrosis (rhabdomyolysis) causes acute renal injury. In the first part of the study, 35 animals were randomized to a peptide-based enteral diet or water via a duodenal feeding tube and subsequently in jected with glycerol. Seventy-eight percent (14 of 18) of the animals receiving the enteral diet survived 3 d compared with 35% (six of 17) of the water-fed animals (p < 0.05). Blood urea nitrogen (47 +/- 8 ver sus 137 +/- 27 mg/dl) and creatinine (0.8 +/- 0.1 versus 2.0 +/- 0.3 m g/dl) were significantly lower in the enteral survivors than in the wa ter survivors. In the second part of the study, renal plasma flow (par a-aminohippurate clearance) and glomerular filtration rate (inulin cle arance) were measured in similarly treated animals (n = 14) 1 d after injury. Renal plasma flow (4.83 +/- 0.65 versus 2.37 +/- 0.62 ml/min) and glomerular filtration rate (2.05 +/- 0.27 versus 0.89 +/- 0.22 ml/ min) were significantly higher in the enteral group than in the water group. These data indicate that enteral feeding can prolong survival a nd decrease renal injury after glycerol-induced rhabdomyolysis. The me chanism for the protection is partly related to maintenance of renal b lood flow.