Prolonged enteral nutrition in malnourished patients with nonelemental feeding. Reappraisal of surgical technique, safety, and costs

Enteral nutrition and the critically ill

Critically ill patients invariably require nutritional intervention. Traditionally, enteral nutrition has not been widely employed in this patient population. This is due in part to the success of present-day parenteral nutrition, and to difficulties encountered with enteral feeding. Recent evidence has demonstrated that enteral is preferable to parenteral nutrition in terms of cost, complications, gut mucosal maintenance, and metabolic and immune function. Enterally administered nutritional support can and should be utilised as the preferred route of nourishment for the critically ill. The appropriate choice of access and formula, as well as a rational strategy for implementation, should improve the likelihood of success. This article describes the unique features of critical illness as they pertain to nutritional support, the benefits of enteral nutrition, and the obstacles to success, and offers suggestions which may improve the ability to provide nutrients adequately via the intestinal tract.

Clinical comparison of tolerance to elemental or polymeric enteral feedings in the postoperative patient

Thirty consecutive patients (19-71 years of age) undergoing abdominal operations and having feeding catheter jejunostomy tubes placed, were prospectively randomized and studied for tolerance to elemental (amino acid) or polymeric (intact protein isolates) dietary formulas. The groups were matched for sex, age, height, weight, operations, and caloric goal. Nutritional profiles of the patients were similar preoperatively. The number of stools/day and stool consistency were direct indicators of tolerance; nutrient intake was an indirect indicator. Diarrhea is defined as greater than or equal to five stools/day. We found no significant difference between the groups. There were no patients with diarrhea on days 1 or 2. Formula intake as an indirect measure of tolerance was not significantly different for the two groups from days 1-4. On day 5, intake of the elemental group exceeded that of the polymeric group (p less than 0.02). Enteral caloric intake as percent of caloric goal did not differ. Nitrogen intake, urinary nitrogen, serum prealbumin, body weight, serum sodium, and serum potassium did not differ significantly between the two groups throughout the study. Serum chloride decreased significantly (105 to 99.8 mEq/L) in the elemental group (p less than 0.03). Our study shows that patients undergoing routine gastrointestinal operations will tolerate early enteral feedings (day 1) and that there is no significant difference in tolerance to elemental or polymeric dietary formulas.

Enteral alimentation: administration and complications

Tube feeding is commonly used for providing essential calories and nutrients to the patient otherwise unable to eat. In the last two decades there has been significant expansion in the number and quality of enteral formulas. In this review, we evaluate the indications for each major class of formula, and survey complications associated with formulas and devices that deliver formula. Recommendations for future research are listed.

Protein and carbohydrate absorptive efficiency of chronically malnourished and well-nourished patients during enteral feeding initiation

To investigate the efficiency of protein and carbohydrate absorption, we studied malnourished and well-nourished subjects during the first 72 hours of tube feeding. We furthermore investigated whether differences in absorptive efficiency existed between malnourished patients with and without nongastrointestinal malignancy. Twenty-one subjects starting tube feeding without edema or major organ failure and not on antibiotics (well-nourished controls = 7; malnourished = 7; malnourished with nongastrointestinal malignancy = 7) received 50 kcal/hr Osmolite continuously for 72 hours. Twelve of these subjects completed an additional 48 hours of study where they received 125 kcal/hr continuously. We performed hydrogen breath tests to assess carbohydrate absorption and determined stool nitrogen content to assess protein absorption. We also measured frequency of defecation, stool weight, and stool moisture content. The results of these tests failed to reveal statistically significant differences between the three groups in terms of protein and carbohydrate absorption, as well as failed to demonstrate the presence of diarrhea. We conclude that patients receiving an isoosmolar diet who are malnourished, or malnourished with nongastrointestinal malignancy, absorb carbohydrate and protein as well as well-nourished patients during enteral hyperalimentation.

Isotonic tube feeding formula induces liquid stool in normal subjects: reversal by pectin

Diarrhea is one of the most common complications in patients who receive tube-feeding formulas. Since the colon is the final site of water and electrolyte absorption and ultimately determines fecal composition, diarrhea during tube feeding may result from altered colonic function. The lack of dietary fiber, such as pectin, in tube-feeding formulas may be one of the means by which colonic function is affected. The purpose of this study was to determine the effect of a standard, liquid, commercially available, isotonic tube-feeding formula (ITFF) and the effects of supplementing the ITFF with pectin on colonic function as measured by stool consistency and colonic fluid composition in 13 normal adults. Data were obtained when subjects consumed their regular diet, ITFF, and ITFF supplemented with pectin using the technique of in vivo dialysis of colonic fluid. Ingestion of the ITFF resulted in a significant increase in the percentage of liquid stools compared to a regular diet [median (interquartile range) = 0% (0), 60% (64); p less than 0.01]. Ingestion of the ITFF also resulted in significant decreases in the concentrations of sodium, potassium, and short-chain fatty acids, and increases in pH and osmotic gap in colonic fluid compared to the subjects' regular diet. Supplementing the ITFF with pectin significantly reduced the incidence of liquid stools [0% (0)] and promoted a normalization of colonic fluid composition. The results suggest that the addition of pectin may enhance tolerance to ITFFs.

Needle catheter jejunostomy: an unappreciated and misunderstood advance in the care of patients after major abdominal operations

We evaluated the use of a needle catheter jejunostomy in 83 consecutive patients who underwent complicated abdominal operations. We used the needle catheter jejunostomy to deliver immediate postoperative nutrition (mean, 1,700 kcal/day) in 66 patients for a range of 4 to 80 days. In addition, the needle catheter jejunostomy was used to provide all maintenance fluid and electrolyte needs and to administer almost all required medications. No serious complications were related to use of the needle catheter jejunostomy, although easily controlled diarrhea occurred in 16 patients (19%). We concluded that the needle catheter jejunostomy is a safe and cost-effective means of delivering postoperative nutrition, fluid and electrolytes, and most medications in selected patients undergoing high-risk abdominal operations.

Indications for needle catheter jejunostomy in elective abdominal surgery

Needle catheter jejunostomy for postoperative nutritional support is now employed worldwide. However, there is a large discrepancy regarding indications for this technique which this study attempts to rectify. The need for nutritional support after elective abdominal procedures in 464 patients was analyzed and compared with the experience with needle catheter jejunostomy in 42 patients. The results show that needle catheter jejunostomy is indicated after extensive operations of the upper gastrointestinal tract, for example, esophagectomy, total gastrectomy, and the Whipple procedure. With minor upper gastrointestinal operations, or procedures of the lower gastrointestinal tract, needle catheter jejunostomy should be performed only in patients with poor nutritional status or in the presence of postoperative chemotherapy or radiotherapy. In an unclear situation, liberal insertion of the needle catheter jejunostomy and a postponed decision on enteral feeding is recommended, as there is no significant catheter-related morbidity.

Development of a chronic canine model for measurement of absorption by substrate appearance in portal venous blood

Research in absorption physiology requires animal models which closely resemble the in vivo situation. The description of a new canine model satisfying these requirements is the objective of this report. Dogs were instrumented with indwelling portal vein and carotid artery catheters, a catheter jejunostomy and an electromagnetic flow measuring probe around the portal vein enabling continuous flow recordings. Following intrajejunal infusion of nutritive substrates in the conscious animal, absorption was measured as the product of porto-arterial substrate difference and portal venous flow. The model was validated in five mongrel dogs: (1) Catheters and flow measuring device function over several months. (2) The sensitivity of the method was evaluated following intrajejunal infusion of l-glycine-l-tyrosine and its constituent amino acids. A significant portoarterial concentration difference of both amino acids enabling quantitative measurement of absorption resulted when the peptide was infused at 4 mmoles/hour (20 mM solution, 200 ml/h). (3) Infusion of complete nutritive formulas caused a significant increase in portal venous flow whereas neither saline nor the amino acids or the peptides investigated had a comparable effect. (4) A validation experiment by implantation of a second flow probe distal to the chronically implanted device provided evidence that granulomatous tissue forming around the probe does not alter the accuracy of the flow recording. In summary, this method permits for the first time quantitative measurement of absorption by appearance rates in portal venous blood instead of by disappearance from the intestinal lumen.