Intravenous hyperalimentation. An important adjunct in the treatment of combat casualties

Trial Design in Critical Care Nutrition: The Past, Present and Future

The specialty of nutrition in critical care is relatively modern, and accordingly, trial design has progressed over recent decades. In the past, small observational and physiological studies evolved to become small single-centre comparative trials, but these had significant limitations by today’s standards. Power calculations were often not undertaken, outcomes were not specified a priori, and blinding and randomisation were not always rigorous. These trials have been superseded by larger, more carefully designed and conducted multi-centre trials. Progress in trial conduct has been facilitated by a greater understanding of statistical concepts and methodological design. In addition, larger numbers of potential study participants and increased access to funding support trials able to detect smaller differences in outcomes. This narrative review outlines why critical care nutrition research is unique and includes a historical critique of trial design to provide readers with an understanding of how and why things have changed. This review focuses on study methodology, population group, intervention, and outcomes, with a discussion as to how these factors have evolved, and concludes with an insight into what we believe trial design may look like in the future. This will provide perspective on the translation of the critical care nutrition literature into clinical practice.

Effects of growth hormone and insulin-like growth factor-1 on protein metabolism, gut morphology, and cell-mediated immunity in burned rats

The effects of recombinant human growth hormone (GH) and insulin-like growth factor-1 (IGF-1) were investigated in burned rats. Sprague-Dawley rats were fed exclusively by total parenteral nutrition and were subjected to 20% third-degree scald burns. The rats were then divided into the following three groups: (1) the GH group received GH at a dose of 1 IU.kg-1.d-1 for 2d (n = 10); (2) the IGF group received IGF-1 at a dose of 4 mg.kg-1.d-1 for 2d (n = 19); and (3) the control group received saline (n = 17). Cumulative nitrogen balance increased significantly in the GH (P < 0.01) and IGF (P < 0.01) groups as compared with the control group. There were no differences in nitrogen balance between the GH and IGF groups. Blood glucose was decreased in the IGF group (P < 0.01) and increased in the GH group (P < 0.05) as compared with the control group. The intestinal villus height and wall thickness of the GH and IGF groups were significantly greater than those of the control group. Delayed-type hypersensitivity was enhanced in both the GH and the IGF groups as compared with the control group (both P < 0.01). Furthermore, the increase in the IGF group was significantly greater than that in the GH group (P < 0.05). It was concluded that both GH and IGF-1 improve protein metabolism and immune responsiveness, as well as promote proliferation of the intestinal mucosa.

Effect of parenteral nutrition on cold-induced vasogenic edema in cats

The effect of standard parenteral nutritional formulas on cold-induced vasogenic edema formation in cats was examined and compared to the effects of 5% dextrose, 0.9% saline, and 40.5% mannitol. The amount of vasogenic edema formed during a 3-hour period of fluid infusion following cold injury was quantified by a computerized graphics tablet determination of the volume of Evans blue-dyed white matter. Specific gravity measurements were taken as a measure of white matter water content. Serum osmolality, urine output, arterial blood gases, hematocrit, body temperature, and systolic blood pressure were measured periodically throughout the infusion period. Parenteral nutritional formulas and a 40.5% mannitol solution produced greater changes in serum osmolality than did 5% dextrose or 0.9% saline. Greater changes in serum osmolality were associated with larger calculated volumes of edema in the injured hemisphere and lower water contents in the uninjured hemisphere. The data indicate that hyperosmolar solutions may potentiate vasogenic edema formation when the blood-brain barrier is open.

Total parenteral nutrition, An important therapeutic advance

Total parenteral nutrition (TPN) is a potent form of therapy. It is particularly useful in patients who must undergo surgery or those with conditions that preclude normal feeding. The procedure is not without risk, but better understanding of the basic principles involved, refinements in technique, and experience with its use in different situations have combined to improve the results of therapy over those first obtained. TPN represents an important therapeutic advance and emphasizes the need for an undertanding of nutritional principles by physicians and for a team approach to the management of complicated conditions.