EVALUATION OF A CARBOHYDRATE-FREE DIET FOR PATIENTS WITH SEVERE HEAD-INJURY

Hyperglycemia, which may be caused or exacerbated by conventional diet s, may worsen the neurological outcome from severe head injury, especi ally if secondary ischemic insults occur. The purpose of this study wa s to evaluate an experimental diet intended to replace systemic calori c and protein requirements without producing hyperglycemia. In initial studies in the laboratory, 5 experimental diets were employed in a mi ddle cerebral artery temporary occlusion model. The effects of the die ts on blood biochemistry and on infarction volume were compared in fas ted animals and in animals fed a control diet. Animals fed the experim ental diets had a significantly lower preischemia blood glucose concen tration, a higher blood concentration of ketone bodies, and a smaller infarct volume than the animals fed a control diet. One diet chosen fr om the laboratory study was then evaluated in a clinical study as a ra ndomized, open-label trial. Twenty severely head-injured patients were randomly assigned to be fed the experimental diet, EN-9305, or the co ntrol diet, Osmolyte HN, for the first 2 weeks after injury. Both trea tment groups had similar blood glucose concentrations, averaging 6.33 +/- 0.21 mu mol/mL (114 +/- 4 mg/dL), on day 1 prior to starting the a ssigned diet. Blood glucose concentration increased in the control die t group to a peak of 8.37 +/- 0.94 mu mol/mL (151 +/- 17 mg/dL) on day 7 as the infusion rate of the diet was increased to the final rate. I n the experimental diet group, the blood glucose concentration remaine d unchanged from fasting levels as the diet was advanced. Blood lactat e concentration was lower, and blood ketone body concentrations were h igher in the patients fed the experimental diet. Urinary nitrogen bala nce was better in the experimental diet group, but measures of viscera l protein sparing, including serum albumin, plasma retinol binding pro tein, and total lymphocyte count, were not significantly different in the 2 treatment groups. Measures of cerebral anaerobic metabolism, inc luding CSF lactate concentration and cerebral lactate production, were not significantly different in the 2 treatment groups. These studies suggest that a carbohydrate-free diet such as EN-9305 might have advan tages for patients with severe head injury by replacing systemic calor ic and protein requirements without producing hyperglycemia.