There are no final, prospective, randomized studies to demonstrate outcomes are superior when great attention is paid to assure that patients receive nutritional support. A study by the Canadian Collaborative Study Group, published to date only in abstract form, demonstrated that when nutrition was started early, preferably via the gut and by TPN only if absolutely required (i.e. absolute contraindication to enteral feeding or initial failure to feed by gut), mortality and length of stay decreased.

In our ICU, we have adapted this general strategy. Enteral (NGT) feeding is started in the first 24 hours unless contraindicated (i.e. unable to keep head of bed 30° secondary to shock OR primary gut pathology in which enteral feeding is contraindicated). Hyperalimentation is only used if patients cannot be fed enterally and is started in the first 48 hours. We follow pre-albumin concentrations twice/week to assure proper feeding and tube feeds are regulated by a protocol that titrates them to full caloric needs rapidly and does not stop tube feeds needlessly. This is a nursing protocol (all that is required is a physician's order to begin tube feeds at a given rate and move to the target rate (which should be stated) derived from the nutritionist's note or computed by Harrison-Benedict) "as per protocol." They generally hold tube feeds only when residuals are in excess of 200 ml, after which they try pro-kinetic agents (Reglan) with resumption of feeding as tolerated.

• How to compute proper caloric needs:
  • Harrison Benedict: males: 66+(13.7)wt+(5)ht-(6.8)age
  • females: 655+(9.6)wt+(1.8)ht-(4.7)age
• How to choose feedings. Most of the formulations are 1 kcal/ml. It is best to use the Harrison Benedict equation to compute your patients' needs. However, as a general rule 2000-2500 kcal/D, with 1/3 fat, 1/3 protein, 1/3 carbohydrate is reasonable for most patients until the nutritionist can formulate more customized diets when needed. That means if you target 80 ml/H for most patients, you'll be "in the ball-park" 90% of the time. Patients with renal failure receive a more concentrated 2 kcal/ml formula so you just need to cut everything in half (i.e. initial goal of 40 ml/kg).