Efficacy and Mechanisms of GLN Dipeptide in the SICU

Relative glutamine (GLN) deficiency may contribute to morbidity and mortality in surgical intensive care unit (SICU) patients. During critical illness, GLN utilization by the immune system, gut mucosa and other tissues exceeds endogenous production and plasma GLN concentrations decrease, which may contribute to cellular dysfunction and increase nosocomial infection risk and mortality. Conventional GLN-free parenteral nutrition (PN) has a limited impact on SICU outcomes and does not repair the GLN deficit. Recent pilot data show that GLN dipeptide-supplemented PN decreases nosocomial infections and improves clinical outcomes in SICU patients. The process of benefit is poorly understood, but animal and human data suggest that GLN treatment correlates with a) up-regulation of cytoprotective molecules in blood and tissues [e.g, GSH, specific heat shock proteins (HSPs) and GLN]; and b) improved epithelial barrier defenses and immune cell number and function. Properties of L-GLN limit provision in solution, but the GLN dipeptide alanyl-GLN (AG) confers stability and solubility in PN (AG-PN). Investigators propose a multicenter, double-blind, randomized, controlled phase III trial based on our pilot data to test the hypothesis that AG-PN improves clinical outcomes in SICU patients requiring PN after cardiac, vascular or colonic operations. Subjects will receive either standard GLN-free PN or isocaloric, isonitrogenous, AG-PN until enteral feeds are established. Specific Aim 1 is to determine whether AG-PN decreases hospital mortality, nosocomial infection and other important indices of morbidity. Specific Aim 2 is to obtain novel, mechanistically relevant observational data in the Aim 1 subjects on whether AG-PN a) increases serial blood levels of GSH, HSP-70 and -27, and GLN; b) decreases the presence in serum of the bacterial products flagellin and LPS and the adaptive immune response to these mediators; and c) improves key indices of innate/adaptive immunity. This study is designed to delineate the clinical benefit of a major new nutrition support strategy in high-risk SICU patients. .

Inclusion criteria: 1) A signed informed consent is in place on the patient's chart; 2) The patient is at least 18 but not more than 90 years of age at time of surgery; 3) The patient has a body mass index (BMI) 2.5 mg/dL and is not receiving continuous renal replacement therapy (CRRT) or the patient requires acute hemodialysis postoperatively; 8) The patient has a concomitant burn or trauma injury; 9) The patient has previously undergone an organ transplantation;10) the patient has a history of HIV/AIDS; 11) The patient has received any investigational drug within 60 days prior to study entry; 12) The patient has received enteral or parenteral enteral feedings enriched in arginine and/or glutamine within 30 days prior to study entry; and 13) The patient is unable or unwilling to participate in study procedures such as longitudinal blood draws and out patient follow-up visits, etc. *Encephalopathy for GLND can be diagnosed only in non-chemically sedated patients by the primary critical care physicians or neurologist consultants and is defined as either a comatose state OR severe abnormalities diagnosed by electroencephalogram (EEG), OR if all of the following criteria are met: a) patient goes to sleep but is arousable to verbal and painful stimuli; does not open eyes spontaneously (decreased level of consciousness); b) patient exhibits severe confusion or complete disorientation when aroused (disorientation); c) patient exhibits severe lethargy or bizarre behavior (behavioral dysfunction); and d) patient exhibits inability to cooperate, asterixis, ataxia, clonus, decortication, decerebration, seizures, or rigidity (severe neuromuscular dysfunction). † Patients with malignant metastasis and terminal untreatable carcinoma will be excluded as per the operational definition agreed upon by the Data Safety and Monitoring Board (DSMB). ≠ Please note that the patient should be in the SICU at the initial PN hang time.