Nutritional Support: Route (Total Parenteral versus Total Enteral) (UPDATE IN PROCESS)

I. Statement of the Problem

The metabolic response to injury mobilizes amino acids from lean tissues to support wound healing, immunologic response and accelerated protein synthesis. The goal of aggressive early nutrition is to maintain host defenses by supporting this hypermetabolism and preserve lean body mass. The route of nutrient administration affects these responses, and the benefits of early enteral feeding have been clearly shown. Laboratory and clinical studies reveal beneficial affects of early nutrition on the gut mucosa, immunologic integrity, survival of septic peritonitis, pneumonia, and abscess formation.

Therefore the question arises as to the route to deliver nutrition to the traumatized hypermetabolic patient with multisystem injuries including severe head injuries, burns, and blunt and penetrating mechanisms. There are certainly risks and benefits to enteral and parenteral nutrition in this complicated patient population. The purpose of this review is to determine the benefits and the risks of the route of nutrition in the severely injured patient through peer reviewed publications over the past 25 years and to develop recommendations and guidelines from the conclusions of these studies based on the scientific methodology of these studies.

II. Process

A. Identification of References

References were identified from a computerized search of the National Library of Medicine for English language citations between 1976 and 2000. Keywords included nutrition, enteral, parenteral, trauma, injury, and burn. The bibliographies of the selected references were reviewed for relevant articles not found in the computerized search. Literature reviews, case reports, and editorials were excluded. Twenty-eight articles were identified.

B. Quality of the References

The quality assessment instrument applied to the references was developed by the Brain Trauma Foundation and subsequently adopted by the EAST Practice Management Guidelines Committee. Articles were classified as Class I, II, or III according to the following definitions:

Class I: A prospective, randomized clinical trial. Fourteen articles were chosen and analyzed.

Class II: A prospective, non-comparative clinical study or a retrospective analysis based on reliable data. Ten articles were chosen and analyzed.

Class III: A retrospective case series or database review. Four articles were chosen and analyzed.

III. Recommendations

A. Level I

Patients with blunt and penetrating abdominal injuries should, when feasible, be fed enterally because of the lower incidence of septic complications compared with parenterally fed patients.

B. Level II

Patients with severe head injuries should preferentially receive early enteral feeding, since outcomes are similar compared with parenterally-fed patients. If early enteral feeding is not feasible or not tolerated, parenteral feedings should be instituted.

C. Level III

1. In severely injured patients, TPN should be started by day 7 if enteral feeding is not successful.
2. Patients who fail to tolerate at least 50% of their goal rate of enteral feedings by post-injury day 7 should have TPN instituted but should be weaned when > 50% of enteral feedings are tolerated.

IV. Scientific Foundation

Moore and Jones^[1] reported the benefits of enteral feedings using immediate jejunal feedings in 1986. The patients in this study had laparotomy for severe abdominal injuries (abdominal trauma index [ATI] >15). Nutritional parameters and overall complications were not different between the enterally and parenterally fed groups; the septic morbidity was higher in the parenterally fed group (p <0.025). Peterson et al.^[2] further evaluated this effect and reported that acute phase proteins increased from baseline to a higher extent in the TPN group compared with TEN in patients suffering abdominal trauma with an ATI >15, <40. The TPN group reached a nadir in constitutive proteins at day 10, while the TEN group had a rise in serum albumin and retinol-binding protein (p <0.05). In 1989, Moore et al.^[3] reported further evidence of the reduced septic complications in patients (ATI >15, <40) fed enterally versus parenterally. A meta-analysis of eight prospective, randomized trials attests to the feasibility of early postoperative enteral feedings in high-risk surgical patients. These patients had reduced septic morbidity rates compared with patients fed parenterally.^[4] In 1992 and 1994, Kudsk et al.^{[5] [6]} showed further evidence of the effectiveness of enteral nutrition over parenteral nutrition. In the earlier study, the rate of septic complications including pneumonia, intra-abdominal abscess, and line sepsis were significantly reduced in the enterally fed group of patients with an ATI >15. Furthermore, the sicker patient (ATI >24, ISS >20, transfusions >20 units, and re-operation) had significantly fewer infections. The latter study confirmed the previous report of Peterson et al.^[2] concluding that enteral feeding produces greater increases in constitutive proteins and greater decreases in acute-phase proteins after severe trauma. This is primarily caused by reduced septic morbidity with enteral feeding. Other factors involved in the reduced septic complications include bacterial translocation, endotoxin, interleukins 1, 2, 6, 11, and 12, and macrophage stimulation. These effects are beyond the scope of this review.

One potential disadvantage regarding the enteral approach to nutrition of the trauma patient is the concern that adequate amounts of protein and calories cannot be delivered via this route, due to frequent interruptions in feeding because of multiple operative procedures. Moncure and coworkers have recently shown that, in selected patients, enteral feedings can be safely administered up to the time of transport to the operating room. This approach facilitated delivery of greater amounts of protein and calories without an increase in peri-operative aspiration events.^[7]

In the head-injured patient, the optimal route of administration remains controversial as both routes are effective and each has advantages and disadvantages. One of the earliest studies to show a benefit to the early use of parenteral feedings was by Rapp et al.^[8] in 1983. Patients with severe head injury were randomly assigned to receive enteral or parenteral nutrition. Patients receiving TPN within 72 hours of admission had a lower mortality rate (p<0.0001). Haussman and colleagues^[9] found that combined parenteral and enteral feeding was comparable to parenteral feeding alone with regard to mortality, nitrogen-balance, creatinine, and 3­methylhistidine excretions, but noted that brain-injured patients with impaired gastric function (as evidenced by high gastric residuals), were better treated with parenteral nutrition. Hadley and others^[10] further demonstrated the equal effectiveness of each route. Although the parenteral nutrition group had higher mean daily nitrogen intakes (p<0.01) and mean daily nitrogen losses (p<0.001), there were no significant differences in serum albumin levels, weight loss, incidence of infection, nitrogen balance, and final outcome. A series of studies performed by Young and others^{[11] [12]}, and Ott and colleagues^[13]further defined nutritional support in the head-injured patient. In the laboratory, intravenous hyperosmolar solutions were found to potentiate cerebral edema following head injury. In 1987, Young et al.^[11] reported no significant difference in peak ICP, failed therapy of ICP, serum osmolality, morbidity or mortality, and patient outcome in patients receiving parenteral compared with enteral nutrition. Young et al.^[12] then reported on 51 brain-injured patients in a prospective, randomized trial of parenteral versus enteral nutrition. Not only did the parenteral support patients have better outcomes at 3, 6, and 12 months, but the enteral group had a higher septic complication rate (p<0.008), believed to be due to lower total protein intake, cumulative caloric balance, and negative nitrogen balance. The enterally fed group did not tolerate feedings until a mean of 9 days, and received fewer calories and less protein. Ott et al.^[13] studied enteral feeding intolerance in head-injured patients. They noted that gastric emptying was biphasic and that a majority of brain-injured patients displayed delayed gastric emptying during the post-injury week 1. This delayed and biphasic response persisted through the second week in >50% of the patients. By week 3, most patients exhibited rapid gastric emptying, and all patients tolerated full volume enteral feedings by day 16. Borzotta and colleagues^[14] confirmed the efficacy of enteral and parenteral support using early jejunal feedings in the enteral group and delayed gastric feeding (day 5-9) in the parenteral group. No difference was found regarding measured energy expenditure, protein intake, albumin, transferrin, nitrogen balance, infectious rates, or hospital costs. Thus it appears that, in the head-injured patient, establishment of early and consistent enteral feeding may obviate the need for parenteral nutrition in this patient population. These related issues of timing (early versus late) and site (gastric versus jejunal) of enteral feeding are discussed in greater detail later in this report. Much of this information has been summarized recently in an excellent review published by the Cochrane Library .^[15]

The relative superiority of enteral over parenteral nutrition in the trauma patient should not be used as an excuse for delaying appropriate nutritional support. Total starvation for less than 2 to 3 days in healthy adults causes only glycogen and water losses and minor functional consequences. Functional deficits are evident in healthy normal weight adults who voluntarily restrict food intake after about 15 days of semi-starvation. Many trauma patients are hypermetabolic, and depletion of nutrient stores proceeds more rapidly in the case of total starvation than it does in healthy adults. The functional consequences of total or partial starvation thus evolve more rapidly in the stressed and catabolic patient than in healthy individuals. For these reasons, most investigators recommendachievement of the severely injured patient’s nutritional support goals by post-injury day 7, whether by enteral or parenteral means, or some combination of the two.^[16]

V. Summary

Although the evidence is not abundant, there is scientific support that patients with blunt and penetrating abdominal injuries sustain fewer septic complications when fed enterally as opposed to parenterally. The surgeon must be aware of the potential benefits of enteral feedings in these severely injured patients. The trauma surgeon caring for patients with head injury must weigh the benefits and the risks of the route of nutrient administration, as patients with severe head injuries have similar outcomes whether fed enterally or parenterally. As determined in studies of malnutrition and starvation, the hypermetabolic state of the severely injured patient requires that calorie and protein goals should be achieved by day 7. Patients who fail to tolerate at least 50% of their goal rate of enteral feedings by this time should have TPN instituted.

VI. Future Investigation

Many of the issues related to the route of nutrition in the trauma patient are far from settled. Although the benefits of enteral nutrition in the severely injured patient with abdominal trauma are well documented, the mechanisms (immunologic and physiologic) remain unclear. The route of administration of enteral feedings, the nutrient composition, and the long-term outcome of trauma patients are still areas for future evaluation by clinicians and scientists. The effectiveness of nutritional support in the severely head-injured patient remains a difficult area to evaluate, as the injury itself remains the most significant factor in the outcome of the patient. Prospective studies of nutritional support evaluating long-term outcomes are still required. Previous work has demonstrated the safety and efficacy of enteral and parenteral nutrition in head-injured patients, but their exact roles or the preference of either route has not been demonstrated. Further study is required to determine a cost-effective approach to nutritional support that may improve outcome in severely head-injured patients.

References

1. Moore EE, Jones TN. Benefits of immediate jejunostomy feeding after major abdominal trauma: a prospective randomized study. J Trauma. 1986;26:874-881.
2. Peterson VM, Moore EE, Jones TN, et al. Total enteral nutrition versus total parenteral nutrition after major torso injury: attenuation of hepatic protein synthesis. Surgery. 1988;104:199-207.
3.  Moore FA, Moore EE, Jones TN, McCroskey BL, Peterson VM. TEN versus TPN following major abdominal trauma - reduced septic morbidity. J Trauma. 1989;29:916-922.
4. Moore FA, Feliciano DV, Andrassy RJ, et al. Early enteral feeding, compared with parenteral, reduces postoperative septic complications. The results of a meta-analysis. Ann Surg.1992;216:172-183.
5. Kudsk KA, Croce MA, Fabian TC, et al. Enteral versus parenteral feeding. Effects on septic morbidity after blunt and penetrating abdominal trauma. Ann Surg. 1992;215:503-513.
6. Kudsk KA, Minard G, Wojtysiak SL, Croce M, Fabian T, Brown RO. Visceral protein response to enteral versus parenteral nutrition and sepsis in patients with trauma. Surgery. 1994;116:516-523.
7. Moncure M, Samaha E, Moncure K, et al. Jejunostomy tube feedings should not be stopped in the perioperative patient. J Parenter Enteral Nutr. 1999;;23:356-359.
8. Rapp RP, Young B, Twyman D, et al. The favorable effect of early parenteral feeding on survival in head injured patients. J Neurosurg. 1983;58:906-912.
9. Hausmann D, Mosebach KO, Caspari R, Rommelsheim K. Combined enteral-parenteral nutrition versus total parenteral nutrition in brain-injured patients. A comparative study. Intensive Care Med. 1985;11:80-84.
10. Hadley MN, Grahm TW, Harrington T, Schiller WR, McDermott MK, Posillico DB. Nutritional support and neurotrauma: a critical review of early nutrition in forty-five acute head injury patients. Neurosurgery. 1986;19:367-373.
11. Young B, Ott L, Haack D, et al. Effect of total parenteral nutrition upon intracranial pressure in severe head injury. J Neurosurg. 1987;67:76-80.
12. Young B, Ott L Twyman D, et al. The effect of nutritional support on outcome from severe head injury. J Neurosurg. 1987;67:668-676.
13. Ott L, Young B, Phillips R, et al. Altered gastric emptying in the head-injured patient: relationship to feeding intolerance. J Neurosurg. 1991;74:738-742.
14. Borzotta AP, Pennings J, Papasadero B, et al. Enteral versus parenteral nutrition after severe closed head injury. J Trauma. 1994;37:459-468.
15. Yanagawa T, Bunn F, Roberts I, Wentz R, Pierro A. Nutritional support for head-injured patients. [Review] Cochrane Database of Systematic Reviews [computer file] 2000;(2):CD001530.
16. ASPEN Board of Directors. Guidelines for the use of parenteral and enteral nutrition in adult and pediatric patients. J Parenter Enteral Nutr. 1993;17:20SA.
17. Kalfarentzos F, Kehagias J, Mead N, Kokkinis K, Gogos CA. Enteral nutrition is superior to parenteral nutrition in severe acute pancreatitis: results of a randomized prospective trial. Br J Surg. 1997;84:1665-1669.
18. Heyland D, Cook DJ, Winder B, Brylowski L, Van demark H, Guyatt G. Enteral nutrition in the critically ill patient: a prospective survey. Crit Care Med. 1995;23:1055-1060.
19. Raff T, Hartmann B, Germann G. Early intragastric feeding of seriously burned and long-term ventilated patients: a review of 55 patients. Burns. 1997;23:19-25.
20. Spapen H, Duinslaeger L, Diltoer M, Gillet R, Bossuyt A, Huyghens LP. Gastric emptying in critically ill patients is accelerated by adding cisapride to a standard enteral feeding protocol: results of a prospective, randomized, controlled trial. Crit Care Med. 1995;23:481-485.
21. Hadfield RJ, Sinclair DG, Houldsworth PE, Evans TW. Effects of enteral and parenteral nutrition on gut mucosal permeability. Am J Resp Crit Care Med. 1995;152:1545-1548.
22. Adams S, Dellinger EP, Wertz MJ, Oreskovich MR, Simonowitz D, Johansen K. Enteral versus parenteral nutritional support following laparotomy for trauma: a randomized prospective trial. J Trauma. 1986;26:882-891.
23. Bethel R, Jansen RD, Heymsfield SB, Ansley JD, Hersh T, Rudman D. Nasogastric hyperalimentation through a polyethylene catheter: an alternative to central venous hyperalimentation. Am J Clin Nutr. 1979;32:1112-1120.
24. Page CP, Carlton PK, Aandrassy RJ, Feldtman, RW, Shield CF. Safe, cost-effective postoperative nutrition. Defined formula diet via needle-catheter jejunostomy. Am J Surg.1979;138:939-945.
25. Eyer SD, Micon LT, Konstantinides FN, et al. Early enteral feeding does not attenuate metabolic response after blunt trauma. J Trauma. 1993;34:639-644.
26. Jones TN, Moore FA, Moore EE, McCroskey BL. Gastrointestinal symptoms attributed to jejunostomy feeding after major abdominal trauma: a critical analysis. Crit Care Med.1989;17:1146-1150.
27. Norton JA, Ott LG, McClain C, et al. Intolerance to enteral feeding in the brain-injured patient. J Neurosurg. 1988;68:62-66.
28. Grahm TW, Zadrozny DB, Harrington T. Benefits of early jejunal hyperalimentation in the head-injured patient. Neurosurgery. 1989;25:729-735.

Table

Route of Nutritional Support Evidentiary Table