Enteral versus parenteral feeding. Effects on septic morbidity after blunt and penetrating abdominal trauma

Enteral nutrition support in acute pancreatitis

OBJECTIVE

To review the controversies surrounding the use of nutritional interventions, particularly enteral support, in patients with acute pancreatitis.

DATA SOURCES

Articles were obtained through a MEDLINE search (1966-June 1999). Additionally, several textbooks containing information on the diagnosis and management of acute pancreatitis were reviewed. The bibliographies of retrieved publications and textbooks were reviewed for additional references.

STUDY SELECTION

All original investigations in humans pertaining to the use of enteral nutritional support in acute pancreatitis were reviewed for inclusion. Studies that investigated parenteral nutrition in acute pancreatitis were also reviewed, with preference given to controlled comparisons with enteral regimens or no nutritional support.

DATA EXTRACTION

The primary outcomes extracted from the literature were time to oral feeding tolerance, complications (e.g., infection) associated with nutritional support, and length of stay.

DATA SYNTHESIS

The duration of pancreatitis and time to oral feedings is similar whether patients receive enteral (i.e., jejunal tube feedings) or parenteral nutrition. Additionally, complications, length of stay, and costs are either similar or decreased with enteral versus parenteral nutrition.

CONCLUSIONS

Current evidence suggests that the enteral rather than parenteral route should be used to provide nutrition to patients with acute pancreatitis. Parenteral nutrition should be reserved for patients in whom nasojejunal feeding is not possible.

Maximizing tolerance of enteral nutrition in severely injured trauma patients: a comparison of enteral feedings by means of percutaneous endoscopic gastrostomy versus percutaneous endoscopic gastrojejunostomy

BACKGROUND

Intolerance of enteral nutrition interrupts caloric balance and increases hospital costs. This study proposes that enteral feeding by percutaneous endoscopic gastrojejunostomy (PEGJ) provides continuous uninterrupted nutrition with greater consistency than percutaneous endoscopic gastrostomy (PEG).

METHODS

This prospective nonrandomly assigned study was conducted at a Level I trauma center from December of 1997 through October of 1998. All feeding tubes were placed by trauma/critical care surgeons for nutritional support. Feeding course was monitored for 14 days from time of tube placement. Demographic data and outcome variables compared were age, sex, Injury Severity Score, Abbreviated Injury Score, hospital length of stay, number of days to reach nutritional goal feedings, caloric goal, protein goal, cc/hr at goal, total parenteral nutrition usage, complications, and hospital charges. Statistical analyses used the independent samples t test, Cox regression, and Pearson chi2 with significance level set at 0.05.

RESULTS

Patients receiving enteral nutrition by PEGJ reached nutritional goal sooner than patients who received enteral nutrition by PEG (p = 0.02). Thirty-seven of 46 PEGJ patients (80%) were at goal rate at day 3, whereas 28 of 43 PEG patients (65%) were at goal on day 3. Nine of 43 PEG patients (21%) and 3 of 46 PEGJ patients (7%) failed to reach goal within 14 days.

CONCLUSION

This study suggests that enteral nutrition delivered by means of PEGJ is better tolerated than enteral nutrition delivered by means of PEG in trauma patients with no abdominal conditions that preclude percutaneous feeding tube placement.

Sequential single doses of cisapride, erythromycin, and metoclopramide in critically ill patients intolerant to enteral nutrition: a randomized, placebo-controlled, crossover study

OBJECTIVE

To evaluate the comparative efficacy of enteral cisapride, metoclopramide, erythromycin, and placebo for promoting gastric emptying in critically ill patients with intolerance to gastric enteral nutrition (EN).

DESIGN

A randomized, crossover study.

SETTING

Adult medical intensive care unit at a university-affiliated private hospital and trauma intensive care unit at a university teaching hospital.

PATIENTS

Ten adult, critically ill, mechanically ventilated patients not tolerating a fiber-containing EN product defined as a single aspirated gastric residual volume >150 mL or two aspirated gastric residual volumes >120 mL during a 12-hr period.

INTERVENTIONS

Patients received 10 mg of cisapride, 200 mg of erythromycin ethylsuccinate, 10 mg of metoclopramide, and placebo as 20 mL of sterile water every 12 hrs over 48 hrs. Acetaminophen solution (1000 mg) was administered concurrently. Gastric residual volumes were assessed, and plasma acetaminophen concentrations were serially determined by TDx between 0 and 12 hrs to evaluate gastric emptying.

MEASUREMENTS AND MAIN RESULTS

Gastric residual volumes during the study were not significantly different between agents. No differences in area under the concentration vs. time curve or elimination rate constant were identified between agents. Metoclopramide and cisapride had a significantly shorter mean residence time of absorption than erythromycin (6.3+/-4.5 [SEM] mins and 10.9+/-5.8 vs. 30.1+/-4.5 mins, respectively [p<.05]). Metoclopramide (9.7+/-15.3 mins) had a significantly shorter time to peak concentration compared with erythromycin and placebo (60.7+/-8.1 and 50.9+/-13.5 mins, respectively [p<.05]). The time to onset of absorption was significantly shorter for metoclopramide vs. cisapride (5.7+/-4.5 vs. 22.9+/-5.7 mins [p<.05]).

CONCLUSION

In critically ill patients intolerant to EN, single enteral doses of metoclopramide or cisapride are effective for promoting gastric emptying in critically ill patients with gastric motility dysfunction. Additionally, metoclopramide may provide a quicker onset than cisapride.

Gastrointestinal surgical patients' outcomes influenced by nutrition

Nutritional support differs for patients electing to have gastrointestinal surgical procedures and patients with abdominal trauma injuries. Trauma patients can rehabilitate more quickly than patients undergoing gastrointestinal surgeries, despite the traumatic injuries that require surgical intervention. This literature review examines and evaluates the clinical practice and management of these patients and the consequences of surgical nutritional deprivation.

Trauma intensive care

Management of the traumatically injured patient in the intensive care unit is a complex and challenging area of general surgery. The problems encountered in the intensive care unit are the source of exciting clinical and basic science research. The future of caring for the severely injured patient suffering from the complications of trauma will undoubtedly further bond the art of clinical medicine to the accomplishments of developing technology and molecular biology.

Bombesin recovers gut-associated lymphoid tissue and preserves immunity to bacterial pneumonia in mice receiving total parenteral nutrition

OBJECTIVE

To study the ability of bombesin (BBS) to recover gut-associated lymphoid tissue (GALT) and preserve immunity in a lethal model of Pseudomonas aeruginosa (Ps) pneumonia in mice receiving total parenteral nutrition (TPN).

SUMMARY BACKGROUND DATA

TPN causes depression of mucosal immunity compared with enterally fed animals, which may explain the increased incidence of pneumonia in parenterally fed trauma patients. BBS prevents this TPN-induced GALT atrophy, depressed gastrointestinal and respiratory tract IgA levels, and impaired antiviral IgA-mediated mucosal immunity. The authors examined whether some supplement could be added to TPN to avoid this GALT atrophy and lower the incidence of infectious complications in the parenterally fed animal.

METHODS

Male mice were randomized to chow or intravenous (IV) TPN. After 5 days of IV TPN, mice received 0, 1, 2, or 3 days of BBS IV three times a day and then were killed to harvest Peyer's patch, intraepithelium, and lamina propria for cell yields. Gastrointestinal and respiratory tract IgA levels were analyzed by enzyme-linked immunosorbent assay. Next, mice underwent intranasal inoculation with liposomes alone (nonimmune) or liposome-containing Ps polysaccharide. Ps immune mice were catheterized and randomized to chow, IV TPN, or IV TPN + BBS. The liposome group received chow but no IV catheter. These mice were given an LD90 dose of intratracheal Ps, and death rates were recorded.

RESULTS

GALT and gastrointestinal and respiratory tract IgA levels improved to those in chow-fed mice after 3 days of BBS. Immunization reduced the death rate from 92% in chow-fed liposome-only animals to 20% in immunized animals. TPN-fed animals lost their mucosal immunity, with a death rate of 86% compared with 21% in the TPN + BBS group.

CONCLUSION

The results demonstrate that BBS reverses TPN-induced changes in GALT and preserves mucosal immunity. Ps immunization reduces the death rate in a gram-negative pneumonia model and maintains gastrointestinal and respiratory immunity in Ps immune mice receiving IV TPN.

The role of the gastrointestinal tract in postinjury multiple organ failure

Despite intensive investigation, the pathogenesis of postinjury multiple organ failure (MOF) remains elusive. Laboratory and clinical research strongly implicate that the gastrointestinal tract plays a pivotal role. Shock with resulting gut hypoperfusion appears to be one important inciting event. While early studies persuasively focused attention on bacterial translocation as a unifying mechanism to explain early and late sepsis syndromes that characterize postinjury MOF, subsequent studies suggest that other gut-specific mechanisms are operational. Based on our Trauma Research Center observations and those of others, we conclude that: 1) bacterial translocation may contribute to early refractory shock; 2) for patients who survive shock, the reperfused gut appears to be a source of proinflammatory mediators that may amplify the early systemic inflammatory response syndrome; and 3) early gut hypoperfusion sets the stage for progressive gut dysfunction such that the gut becomes a reservoir for pathogens and toxins that contribute to late MOF.

New concepts in the management of patients with penetrating abdominal wounds

In the future, trauma research and care will have to become better, faster, and less expensive. Surgeons in the next millennium must be able to diagnose wounds, initiate correct procedures, and anticipate complications more accurately than before. Violent crime will not abate, nor will the proliferation of more powerful arms; these trends translate into graver traumatic wounds, giving the operating team less time to stabilize patients. Time management and team coordination are becoming key elements for patient survival, especially for patients with potentially fatal wounds, such as those to the heart. The authors have reduced the time from arrival to surgery to a few minutes. The keys to this feat are readiness, team coordination, and high morale. Financial resources will continue to be limited and allocated on a need-first basis. In the future, trauma centers will compete for dwindling funds. Technology is and always will be just a tool, whereas qualified trauma surgeons are irreplaceable, much more so than in any other surgical specialty. Observation, diagnosis, and surgery are, of course, greatly facilitated by ever-evolving technology, but since the time of Hippocrates, split-second decisions can ultimately be made only by the caregiver in the white smock. Trauma surgeons in the next millennium will have to exercise judgment based on knowledge, surgical skills, and contact with patients. To err is human, but in surgery, errors often cause death, and no machine will ever relieve surgeons of that burden.

Complications of surgical feeding jejunostomy in trauma patients

OBJECTIVE

To determine the complication rate of feeding jejunostomy (FJ) performed as an adjunct to trauma celiotomy.

METHODS

Retrospective analysis of 222 patients from January of 1988 to May of 1998.

RESULTS

Thirty-seven total FJ-related complications occurred in 22 patients (10%). Major FJ-related complications occurred in nine patients (4%): two small bowel perforations, two small bowel volvuli with infarction, two intraperitoneal leaks, and three small bowel necroses. Patients suffering major FJ-related complications were similar to those without complications, except for the FJ type. Patients with major FJ-related complications were more likely to have had a Witzel tube jejunostomy than a needle catheter jejunostomy (p = 0.03). Three deaths were related to major FJ complications, for a FJ-related mortality rate of 1.4%.

CONCLUSIONS

FJ has a major complication rate of 4% in severely injured patients. Major complications occur more frequently with larger, Witzel-type tubes. Needle catheter jejunostomy appears to be a safer method of surgical jejunal access in trauma patients.

Prevention of multiple organ failure

Physicians are still largely ignorant of the underlying biology of SIRS and multiple organ failure. Nonetheless, strategies to prevent multiple organ failure are possible. These include aggressive resuscitation of hemodynamically unstable patients, careful assessment to avoid missing clinically significant injuries, early operative treatment of all possible injuries with debridement of all nonviable tissue, early nutritional support, and the early diagnosis and prompt treatment of infectious complications. Treatment of patients with established multiple organ failure is still largely supportive and has made little impact on the patient mortality rate over the past 20 years. Future treatment strategies must focus on multimodality combination therapy aimed at specifically suppressing excessive activation of the inflammatory response while preserving immune competence and normal antimicrobial defenses. Only then are physicians likely to begin to see a reduction in the mortality rate of patients with this complex and challenging condition.

Intestinal obstruction secondary to enteral feedings in burn trauma patients

BACKGROUND

Enteral feeding is preferred for maintaining gut integrity and providing nutrition in trauma patients. Recent reports suggest that use of early enteral feeds is successful and that complications are rare. A recent burn patient, who suffered apparent bowel obstruction and perforation secondary to enteral feedings, led us to review our experience with mechanical complications of tube feedings.

METHODS

We searched our registry of patients treated for acute burn trauma injury and identified patients treated for acute bowel obstruction in the past 3 years.

RESULTS

Four patients were identified, ages 22 to 44, with burns of 6 to 92% total body surface area. Each required intubation and ventilatory support during initial treatment, complicated by adult respiratory distress syndrome and sepsis. We began enteral feeds 1 to 3 days after admission. At approximately 14 days after admission, each patient deteriorated clinically, which led to emergent abdominal exploration; the tube feedings caused bowel obstruction and associated complications. Each patient improved with laparotomy.

CONCLUSION

Bowel obstruction, ischemic necrosis, or both, secondary to early and aggressive nutrition with a fiber supplemented enteral feeding is an uncommon, life-threatening complication. Understanding and early recognition of this potential complication are essential to prevention or successful treatment.

Gastric emptying of liquids and postprandial pancreatobiliary secretion are temporarily impaired during endotoxemia

The aims of our study were to determine mechanisms by which pancreatobiliary secretion is altered during endotoxemia. Dogs underwent placement of duodenal perfusion and aspiration catheters and antral manometry catheters. Gastric emptying of liquids, antral motility, output of bile acids and amylase, and serum levels of enteric hormones were determined after ingestion of a 360-kcal mixed-nutrient liquid meal. Each dog was then given a single dose of E. coli lipopolysaccharide (200 microg/kg, intravenously) and the studies repeated for the next three days. Endotoxin slowed gastric emptying of liquids and decreased amylase output for two days. Bile acid output was decreased on postendotoxin day 1. Pancreatic polypeptide alone was decreased on postendotoxin day 1. We conclude that the decrease in pancreatobiliary output is probably due to decreased nutrient flow into the duodenum and not due to decreased production of hormones that influence pancreatobiliary secretion. The delayed gastric emptying, decreased pancreatobiliary output, and decreased postprandial levels of pancreatic polypeptide suggest diminished vagal output as a possible explanation for the effects of endotoxin on upper gut function.

A prospective, randomized clinical trial on perioperative feeding with an arginine-, omega-3 fatty acid-, and RNA-enriched enteral diet: effect on host response and nutritional status

BACKGROUND

The use of immune-enhancing enteral diets in the postoperative period has given contrasting results. The purpose of this prospective, randomized, double-blinded clinical study was to evaluate the effect of immunonutrition given perioperatively on cytokine release and nutritional parameters.

METHODS

Patients with cancer of the stomach or colo-rectum were eligible. Subjects consumed 1 L/d of either a control enteral formula (n = 25; control group) or a formula supplemented with arginine, omega-3 fatty acids, and RNA (n = 25; verum group) for 1 week before surgery. Both formulas were given by mouth. Six hours after the operation, jejunal infusion with the same diets was started and maintained for 7 days. Blood was drawn at different time points to assess albumin, prealbumin (PA), transferrin, cholinesterase activity, retinol binding protein (RBP), interleukin-2 receptors alpha (IL-2Ralpha), IL-6, and IL-1 soluble receptors (IL-1RII). The composite score of delayed hypersensitivity response (DHR) to skin test also was determined (the higher the score, the lower the immune response).

RESULTS

During the 7 days of presurgical feeding, none of the above parameters changed in either group. Eight days after operation, in the control group, the concentration of PA and RBP was lower than in the verum group (0.18 vs 0.26 g/L for PA and 30.5 vs 38.7 mg/L for RBP; p < .05). IL-2Ralpha concentration was 507 pg/mL in the verum group vs 238 pg/mL in the control group (p < .001), whereas IL-6 and IL-1RII were higher in the control group than in the verum group (104 vs 49 and 328 vs 183 pg/mL, respectively; p < .01). The DHR score was 0.68 in the control group vs 0.42 in the verum group (p < .05).

CONCLUSIONS

Perioperative feeding with a supplemented enteral diet modulates cytokine production and enhances cell-mediated immunity and the synthesis of short half-life proteins.

Jejunostomy tube feedings should not be stopped in the perioperative patient

BACKGROUND

Anesthetic standard of care is to restrict oral intake for 8 hours before elective surgery. There is no research addressing appropriate preoperative discontinuation of jejunostomy tube (J-tube) feedings. We hypothesized that patients could be fed safely, via a J-tube, until the time of surgery.

METHODS

Patients admitted to a Level I Trauma Center, having J-tubes and undergoing a nonabdominal operation, were prospectively evaluated. Group I patients received J-tube feedings until transport to the operating room. Group II patients had tube feedings discontinued for at least 8 hours before surgery. Data were compared using the Student's t test and contingency table analysis.

RESULTS

There were 46 patients in group I and 36 in group II. There was no incidence of aspiration. Patient groups did not differ in age, mortality, length of stay, injury severity score, or ventilator days. Group I patients had tube feedings discontinued for fewer hours before and after surgery than group II patients (before surgery: 1.40 +/- 1.20 vs 11.61 +/- 5.01, respectively; p < .001; after surgery: 2.99 +/- 7.49 vs 7.11 +/- 9.03, respectively; p = .043); received more kilocalories/ grams of protein on the day of surgery (group I vs group II, 1676.15/89.57 +/- 1133.21/38.04 vs 791.14/57.58 +/-498.66/79.87, respectively; p = .001/p = .032) and more kilocalories/grams of protein on the first postoperative day (group I vs group II, 1580.74/92.57 +/- 600.53/37.96 vs 1152.47/63.53 +/- 733.96/39.40, respectively; p = .006/p = .001).

CONCLUSIONS

Patients receiving J-tubes who are undergoing nonabdominal operations may safely continue enteral nutrition at maximum protein and caloric intake until surgery.

Gastrointestinal flora and its alterations in critical illness

The normal indigenous flora of the human gastrointestinal tract comprises a remarkably complex yet stable colony of more than 400 separate species, living in a symbiotic relationship with the human host. Stability of that flora is accomplished by multiple mechanisms including gastric acidity, gut motility, bile, products of immune cells in the gut epithelium, and competition between microorganisms for nutrients and intestinal binding sites. The indigenous flora influences multiple aspects of physiologic homeostasis and forms a key component of normal host defenses against infection by exogenous pathogens. Critical illness is associated with striking changes in patterns of microbial colonization, best described in the oropharynx and upper gastrointestinal tract. Pathological colonization occurs with the same species that is predominate in nosocomial infections, and descriptive studies suggest that such colonization is a risk factor for infection. Moreover, prophylactic measures that prevent pathological gut colonization in experimental circumstances reduce rates of nosocomial infection in critically ill patients and, in the case of selective decontamination of the digestive tract, reduce mortality risk. Conventional approaches to infectious diseases have conceptualized microorganisms as inimical and focused on eradicating them as rapidly and fully as possible. Insights from the study of critically ill patients suggest that that relationship is better understood as a symbiotic one and that preservation, rather than elimination, of the indigenous flora provides the greatest promise of clinical benefit to this vulnerable population.

Enteral nutrition in patients with pancreatitis

Nutritional support in the form of total parenteral nutrition (TPN) or enteral nutrition (EN) is successfully used in patients with pancreatitis, in whom the goal is to provide optimal nutrition while minimizing pancreatic exocrine activity. Controversy continues as to whether TPN or EN is more appropriate. Although TPN is traditionally preferred in acute pancreatitis, EN offers some advantages, being more physiologic, safer, and more cost-effective. A review of available animal and human studies suggests that elemental diets may be effective in patients with mild acute pancreatitis. In patients who have no clinical indication for restricting the gastrointestinal tract, EN may be preferred.

Nutritional and metabolic aspects of gastrointestinal cancer

The profound impact of nutrition and nutritional support on the development and clinical outcome of gastrointestinal cancer is undeniable. However, scientific investigation into this area is recent, and many questions remain unanswered. While the importance of 'good nutrition' is unchallenged, details relating to which patients should receive nutritional support, when they should receive it, and what type of support they should receive are not known. Recent prospective randomized clinical trials and meta-analysis have provided conflicting results. This review summarizes the results of the published studies that have addressed these issues, and provides specifics regarding the current role of nutritional support in clinical care, and the prospects for future research.

Infusion protocol improves delivery of enteral tube feeding in the critical care unit

BACKGROUND

Numerous factors may impede the delivery of enteral tube feedings (ETF) in the intensive care unit (ICU). We designed a prospective study to determine whether the use of an infusion protocol could improve the delivery of ETF in the ICU.

METHODS

In a prior prospective study, we monitored all patients admitted to the medical intensive care unit (MICU) or cardiac care unit (CCU) who were made nil per os and placed on ETF (control group). We found that critically ill patients received only 52% of their goal calories, primarily due to physician underordering (66% of goal), frequent cessations of ETF (22% of the time), and slow advancement (14% at goal by 72 hours). Based on these findings, we developed an ETF protocol that incorporated standardized physician ordering and nursing procedures, rapid advancement, and limited ETF interruption. After extensive educational sessions, the ETF protocol was begun. Again, all patients admitted to the MICU or CCU who were made nil per os and placed on ETF were prospectively followed (protocol group).

RESULTS

Thirty-one patients in the protocol group were followed during 312 days of ETF and compared with the control group (44 patients with 339 days of ETF). Despite efforts by the nutritional support team, the infusion protocol was used in only 18 patients (58%). The main reasons for noncompliance with the protocol were physician preference and system failure (ETF order sheet not placed in chart). When used, the infusion protocol improved physician ordering (control 66% of goal volume, noncompliant 68%, compliant 82%, p < .05); delivery of calories (control 52% of goal, noncompliant 55%, compliant 68%, p < .05); and advancement of ETF (control 14% at goal by 72 hours, noncompliant 31%, compliant 56%, p < .05). Although significant reduction in ETF cessation due to nursing care was noted, it represented only a fraction of the total time ETF were stopped. Cessation due to residual volumes, patient tolerance, and procedure continued to be a frequent occurrence and was often avoidable.

CONCLUSIONS

An evidence-based infusion protocol improved the delivery of ETF in the ICU, primarily because of better physician ordering and more rapid advancement. The nursing staff rapidly assimilated these changes. However, physicians' reluctance to use the protocol limited its efficacy and will need continued educational efforts.

Gut origin of sepsis: a prospective study investigating associations between bacterial translocation, gastric microflora, and septic morbidity

AIMS

To investigate the "gut origin of sepsis" hypothesis.

METHODS

Prospective controlled study of 279 surgical patients in which cultures of nasogastric aspirates were compared with those obtained from mesenteric lymph nodes taken at laparotomy and the organisms cultured from subsequent septic complications. Bacterial translocation was confirmed if positive cultures were obtained from mesenteric lymph nodes. Postoperative sepsis was defined as any positive culture in the postoperative period. Bacterial species obtained in gastric microflora, mesenteric lymph nodes, and postoperative septic complications were compared.

RESULTS

Only 85/279 patients (31%) had a sterile nasogastric aspirate; the most frequently identified organism was Candida spp. (54%) and the most common enteric organism cultured was E coli (20%). Multiple organisms were isolated in 39% and occurred more frequently in patients aged over 70 years, those undergoing non-elective surgery, and in those requiring proximal gastrointestinal surgery. Postoperative sepsis was more common in these patients. Bacterial translocation occurred in 21% and was significantly more frequent in those with multiple organisms in their nasogastric aspirates. E coli was the commonest organism isolated from the lymph node specimens (48%) and septic foci (53%). Fungal translocation did not occur. An identical genus was identified in the nasogastric aspirate and the septic focus in 30% of patients, in the nasogastric aspirate and the lymph node in 31%, and in the lymph node and a postoperative septic focus in 45%.

CONCLUSIONS

Proximal gut colonisation is associated with both increased bacterial translocation and septic morbidity. The commonality of organisms identified supports the gut origin of sepsis hypothesis.

Enteral nutrition-related gastrointestinal complications in critically ill patients: a multicenter study. The Nutritional and Metabolic Working Group of the Spanish Society of Intensive Care Medicine and Coronary Units

OBJECTIVE

To evaluate the frequency of gastrointestinal complications (GICs) in a prospective cohort of critically ill patients receiving enteral nutrition and to assess its effect on nutrient administration and its relationship to the patient's outcome.

DESIGN

Multicenter, prospective cohort study.

SETTING

Thirty-seven multidisciplinary intensive care units (ICUs) in Spain.

PATIENTS

Prospective cohort of 400 consecutive patients admitted to the ICU and receiving enteral nutrition.

INTERVENTIONS

Noninterventional, follow-up study.

MEASUREMENTS AND MAIN RESULTS

Enteral nutrition-related GICs and their management were defined by consensus before data collection. A set of variables related to enteral nutrition administration and the presence of GICs was recorded. During the 1-month study period, 400 patients were enrolled, and a total of 3,778 enteral feeding days were analyzed. The mean time of enteral nutrition was 9.6+/-0.4 days. Mean elapsed time from ICU admission to the start of enteral feeding was 3.1+/-0.2 days. A total of 265 patients (66.2%) received a standard polymeric formula, and 132 (33.8%) received a disease-specific one. Enteral feeds were administered mainly through a nasogastric tube (91%). One or more GICs were presented by 251 patients (62.8%) during the feeding course. The frequency of each particular GIC was as follows: high gastric residuals, 39%; constipation, 15.7%; diarrhea, 14.7%; abdominal distention, 13.2%; vomiting, 12.2%; and regurgitation, 5.5%. Enteral nutrition withdrawal as a consequence of noncontrollable GICs occurred in 15.2% of patients. The volume ratio (expressed as the ratio between administered and prescribed volumes) was calculated daily and was used as an index of diet administration efficacy. Patients with GICs had a lower volume ratio than did patients without GICs (63.1+/-1.20% vs. 93.3+/-0.3%) (p < .001), a longer length of stay (20.6+/-1.2 vs. 15.2+/-1.3 days) (p < .01), and higher mortality (31% vs. 16.1%) (p < .001).

CONCLUSIONS

The frequency of enteral nutrition-related GICs in critically ill patients is high. High gastric residuals is the most frequent GIC. These complications decreased nutrient intake and, if persistent, could expose the patients to undernutrition. Enteral feeding gastrointestinal intolerance seems to have an evolutive effect in prolonging the ICU stay and increasing patient mortality.

Enteral tube feeding in the intensive care unit: factors impeding adequate delivery

OBJECTIVE

To evaluate those factors that impact on the delivery of enteral tube feeding.

DESIGN

Prospective study.

SETTING

Medical intensive care units (ICU) and coronary care units at two university-based hospitals.

PATIENTS

Forty-four medical ICU/coronary care unit patients (mean age, 57.8 yrs; 70% male) who were to receive nothing by mouth and were placed on enteral tube feeding.

INTERVENTIONS

Rate of enteral tube feeding ordered, actual volume delivered, patient position, residual volume, flush volume, presence of blue food coloring in oropharynx, and stool frequency were recorded every 4 hrs. Duration and reason for cessation of enteral tube feeding were documented.

MEASUREMENTS AND MAIN RESULTS

Physicians ordered a daily mean volume of enteral tube feeding that was 65.6% of goal requirements, but an average of only 78.1% of the volume ordered was actually infused. Thus, patients received a mean volume of enteral tube feeding for all 339 days of infusion that was 51.6% of goal (range, 15.1% to 87.1%). Only 14% of patients reached > or = 90% of goal feeding (for a single day) within 72 hrs of the start of enteral tube feeding infusion. Of 24 patients weighed before and after, 54% were noted to lose weight on enteral tube feeding. Declining albumin levels through the enteral tube feeding period correlated significantly with decreasing percent of goal calories infused (p = .042; r2 = .13). Diarrhea occurred in 23 patients (52.3%) for a mean 38.2% of enteral tube feeding days. In >1490 bedside evaluations, patients were observed to be in the supine position only 0.45%, residual volume of >200 mL was found 2.8%, and blue food coloring was found in the oropharynx 5.1% of the time. Despite this, cessation of enteral tube feeding occurred in 83.7% of patients for a mean 19.6% of the potential infusion time. Sixty-six percent of the enteral tube feeding cessations was judged to be attributable to avoidable causes.

CONCLUSIONS

The current manner in which enteral tube feeding is delivered in the ICU results in grossly inadequate nutritional support. Barely one half of patient caloric requirements are met because of underordering by physicians and reduced delivery through frequent and often inappropriate cessation of feedings.

Effect of nutritional route on colonic anastomotic healing in the rat

Although early enteral feeding has been shown to benefit cutaneous healing when compared to parenteral feeding, the effect of the route of nutritional support in gastrointestinal anastomotic healing has not been defined. The aim of the present study was to determine whether the route of nutritional support influences colonic anastomotic healing. Twenty male Sprague-Dawley rats weighing 270 to 290 grams underwent identical surgical manipulation consisting of central venous catheterization, gastrostomy insertion, and distal colonic anastomosis (single-layer, inverted). Identical nutrient infusates composed of 4.25% amino acids, 25% dextrose, and vitamins were administered, with half the animals receiving the infusions via the gastrostomy and the other half via the venous catheter. Animals were killed 5 days after surgery. There were no differences in nutritional parameters between the parenterally and enterally fed groups. Colonic anastomotic bursting pressure was significantly higher in the enterally fed group (180 +/- 6 vs. 150 +/- 11 mm Hg; P <0.01). The measured insoluble collagen and total protein content in anastomotic tissue were enhanced in the enterally supported group. The fraction of soluble (newly synthesized) collagen did not differ between the two groups. The data demonstrate that the route of nutrient administration influences colonic anastomotic healing. The preservation of colonic structural collagen in the enteral group may improve the ability of the gut to hold sutures and thus enhance anastomotic healing.

Glutamine-enriched total parenteral nutrition preserves respiratory immunity and improves survival to a Pseudomonas Pneumonia

BACKGROUND

Addition of 2% glutamine (GLN), a specific lymphocyte fuel, prevents deleterious effects of TPN on gut-associated lymphoid tissue and IgA while preserving IgA-mediated upper respiratory immunity to influenza virus. We examined whether a 2% GLN-enhanced TPN solution preserves respiratory immunity to a lethal and clinically relevant pneumonia challenge.

MATERIALS AND METHODS

Male ICR mice were randomized to chow (n = 20), TPN (n = 20), or an isonitrogenous, isocaloric TPN-2% GLN solution (n = 17). All groups were immunized 10 days before surgery with Pseudomonas polysaccharide-containing liposomes (LIP) to confer immunity except for a nonimmune chow-fed LIP control group (n = 21) which received LIP without Pseudomonas. Mice received 5 days of diet and then were given an LD90 dose of 1.2 x 10(8) intratracheal Pseudomonas bacteria, and mortality was recorded.

RESULTS

Immunization reduced mortality compared with LIP alone. TPN impaired immunity and reduced survival while GLN maintained immunization effectiveness.

CONCLUSIONS

Pseudomonas immunization reduces mortality to Pseudomonas pneumonia, but this immunity is lost with TPN. Addition of 2% GLN to TPN preserves immunity in the respiratory tract and reduces mortality to a lethal bacterial challenge compared with standard TPN.

The gut's role in metabolism, mucosal barrier function, and gut immunology

The gastrointestinal tract functions not only to absorb nutrients, it also plays an important immunologic role during health and critical illness. Under experimental and certain clinical conditions, stimulating the gut attentuates the stress response and avoids mucosal atrophy and increases permeability. Gut stimulation prevents atrophy of the gut-associated lymphoid tissue, the body's major defender of moist mucosal surfaces. A better understanding of gut function and improved nutrient delivery has clinical implications in the treatment of critically ill patients.

Route and type of nutrition influence IgA-mediating intestinal cytokines

OBJECTIVE

To examine the levels of a Th1 IgA-inhibiting cytokine (interferon gamma) and the Th2 IgA-stimulating cytokines (interleukin [IL]-4, IL-5, IL-6, and IL-10) within the intestine of animals manipulated with enteral or parenteral nutrition, and to correlate these cytokine alterations with intestinal IgA levels.

SUMMARY BACKGROUND DATA

Enteral feeding significantly reduces the incidence of pneumonia in critically injured patients compared with intravenous total parenteral nutrition (IV TPN) or no nutritional support. Experimentally, complex diets prevent impairments in mucosal immunity induced by IV TPN. These impairments include decreases in intestinal and respiratory tract IgA levels, impaired IgA-mediated antiviral defenses, and increases in the mortality rate against established immunity to Pseudomonas pneumonia. Intragastric (IG) TPN maintains antiviral defenses but only partially preserves protection against Pseudomonas pneumonia. Because IgA levels depend on interactions between Th1 IgA-inhibiting and Th2 IgA-stimulating cytokines, the authors postulated differences in gut cytokine balance in enterally and parenterally fed mice.

METHODS

Sixty-one mice were randomized to receive chow, IV TPN, IG TPN, or an isocaloric, complex enteral diet. After 5 days of feeding, animals were killed and supernatants from samples of intestine were harvested, homogenized, and assayed for Th1 and Th2 cytokines by enzyme-linked immunosorbent assay.

RESULTS

The Th2 cytokines, IL-5 and IL-6, and the Th1 cytokine, interferon gamma, remained unchanged by diet. IL-4 levels decreased significantly in both IV and IG TPN groups versus the chow or complex enteral diet groups, whereas IL-10 decreased only in IV TPN mice. Decreases in Th2 cytokines correlated with intestinal IgA levels.

CONCLUSION

Chow and complex enteral diets maintain a normal balance between IgA-stimulating and IgA-inhibiting cytokines while preserving normal antibacterial and antiviral immunity. The IgA-stimulating cytokine IL-4 drops significantly in mice receiving IG and IV TPN in association with reduced IgA levels, whereas IL-10 decreases significantly only in mice receiving IV TPN. These data are consistent with severely impaired mucosal immunity with IV TPN and partial impairment with IG TPN and provide a cytokine-mediated explanation for reduction in diet-induced mucosal immunity.

Preoperative issues in clinical nutrition

Allowing a patient's nutritional state to deteriorate through the perioperative period adversely affects measureable outcome related to nosocomial infection, multiple organ dysfunction, wound healing, and functional recovery. Careful preoperative nutritional assessment should include a determination of the level of stress, an evaluation of the status of the GI tract, and the development of specific plans for securing enteral access. Patients already demonstrating compromise of nutritional status (defined by > 10% weight loss and serum albumin level < 2.5 g/dL) should be considered for a minimum of 7 to 10 days of nutritional repletion prior to surgery. Widespread use of total parenteral nutrition in unselected patients is unwarranted, may actually worsen outcome, and should be reserved for preoperative nutritional support only in severely malnourished patients in whom the GI tract is unavailable. Compared with the parenteral route, use of perioperative enteral feeding has been shown to provide more consistent and beneficial results, and can be expected to promote specific advantages in long-term morbidity and mortality.

Appropriate use, complications and advantages demonstrated in 500 consecutive needle catheter jejunostomies

BACKGROUND

The ability to deliver nutrition enterally after operation has been a significant advance in managing patients after major intra-abdominal operations.

METHODS

The experience of a single surgeon at a tertiary referral hospital over a 10-year period with insertion and use of 500 consecutive needle catheter jejunostomies (NCJs) was reviewed critically from prospectively collected data.

RESULTS

The NCJ was used to deliver nutrition in 93 per cent, fluid and electrolytes in 95 per cent, and various medications in the postoperative period in the majority of patients. There were three major complications: small bowel obstruction and pneumatosis intestinalis in one and two patients respectively. Minor complications included diarrhoea (15 per cent), abdominal distension (15 per cent), abdominal cramps (3 per cent), subcutaneous infection at the insertion site (1 per cent) and catheter occlusion precluding use (1 per cent). In 16 patients, the NCJ was replaced percutaneously with a larger-bore catheter for more prolonged enteral feeding at home after discharge.

CONCLUSION

Through the experience gained, indications are offered for the placement of NCJs and cautions are provided concerning appropriate use of an NCJ to provide nutritional support, fluid and electrolyte replacement or maintenance, and safe enteral administration of medication. Overall, an NCJ appears to allow safer, cheaper and equally effective delivery of nutrition compared with total parenteral nutrition after major intra-abdominal operations.

Metabolic and monetary costs of avoidable parenteral nutrition use

BACKGROUND

We prospectively collected data on in patients receiving parenteral nutrition to determine the magnitude of potentially preventable metabolic and monetary costs associated with parenteral nutrition.

METHODS

Parenteral nutrition was prescribed by the treating physicians with optional consultation from a multidisciplinary metabolic support service. Days on parenteral nutrition, appropriateness of parenteral nutrition, metabolic complications, and avoidable parenteral nutrition charges were determined. Parenteral nutrition use was considered "indicated" or "not indicated" based on the American Society for Parenteral and Enteral Nutrition guidelines and "preventable" if the gastrointestinal tract was functional but not accessed when possible.

RESULTS

Of the 209 parenteral nutrition starts, 62% were indicated, 23% were preventable, and 15% were not indicated. Parenteral nutrition starts were deemed indicated in 82% of instances in which a metabolic support service consult was obtained, compared with 56% in which a consultation was not obtained (p = .004). Hyperglycemia was the most common metabolic complication, with an overall incidence of 20%. Metabolic complications occurred less frequently in patients who received a metabolic support service consultation compared with patients who did not (34% vs 66% of parenteral nutrition days, respectively; p = .004). Parenteral nutrition use of < or =5 days duration was significantly less frequent among patients who received metabolic support service consultation (16% vs 35%; p = .002). Parenteral nutrition that was not indicated or preventable resulted in excess annualized patient charges of more than one half million dollars not accounting for charges related to treatment of potentially avoidable parenteral nutrition complications.

CONCLUSIONS

This study illustrates that not-indicated and preventable parenteral nutrition initiation, short-term parenteral nutrition use, and metabolic complications are less likely when patients receive consultation by a multidisciplinary team with expertise in nutrition and metabolic support. Furthermore, the avoidance of inappropriate parenteral nutrition use translates into substantial cost savings.

Glutamine supplementation in catabolic patients

OBJECTIVE

To evaluate the safety and efficacy of parenteral and enteral glutamine supplementation in patients who are catabolic.

DATA SOURCES

English-language clinical trials and review articles identified by MEDLINE searches (January 1970-December 1997) and from bibliographies of selected articles were considered for possible inclusion. Key words used in the search strategy were glutamine, critical illness, stress, catabolism, injury, enteral nutrition, and parenteral nutrition.

STUDY SELECTION AND DATA EXTRACTION

Inclusion was restricted to pertinent studies that evaluated the safety of glutamine supplementation, as well as effects of glutamine on amino acid metabolism, immune function, and patient outcome. Data from 18 clinical trials and multiple review articles were compiled into a review format.

DATA SYNTHESIS

Glutamine is an important metabolic fuel for intestinal enterocytes, lymphocytes and macrophages, and metabolic precursors such as purines and pyrimidines. Although originally considered a nonessential amino acid, experimental work suggests that glutamine is essential for maintaining intestinal function, immune response, and amino acid homeostasis during periods of severe stress. In the past decade, clinical trials conducted in metabolically stressed patients indicate that glutamine improves nitrogen balance, increases cellular proliferation, decreases the incidence of infection, and shortens hospital stay in some catabolic patients.

CONCLUSIONS

Glutamine has been studied extensively over the past decade for its role during critical illness. Clinical trials conducted in humans demonstrate glutamine to be well tolerated without adverse consequences, even during times of stress. Although glutamine has shown promise in select groups of catabolic patients, additional studies are needed to define which patient populations derive the greatest benefit from supplemental glutamine and the mechanisms by which these effects are exerted.

Route and type of nutrition influence mucosal immunity to bacterial pneumonia

OBJECTIVE

To develop a model of established respiratory immunity against Pseudomonas aeruginosa pneumonia and to investigate the effects of route and type of nutrition on this immunity.

SUMMARY BACKGROUND DATA

Diet influences the ability of gut-associated lymphoid tissue (GALT) to maintain mucosal immunity. Complex enteral diets and chow maintain normal GALT populations against established IgA-mediated antiviral respiratory immunity. Both intravenous and intragastric total parenteral nutrition (TPN) produce GALT atrophy, but only intragastric TPN preserves established antiviral immunity. The authors hypothesized that both GALT-depleting diets (intragastric and intravenous TPN) would impair immunity against bacterial pneumonia.

METHODS

P. aeruginosa was administered intratracheally to determine the mortality rate at increasing doses, and liposomes containing P. aeruginosa antigens were used to generate effective respiratory immunization. In the final experiment, mice received liposomes containing P. aeruginosa antigens to establish immunity and then were randomized to chow, complex enteral diets, intragastric TPN, or intravenous TPN. After 5 days of diet, mice received live intratracheal P. aeruginosa, and the death rate was recorded at 24 and 48 hours.

RESULTS

The LD50 and LD100 were 9 x 10(7) and 12 x 10(7), respectively. Immunization reduced the mortality rate from 66% to 12%. This immunization was maintained in mice fed chow or a complex enteral diet and was lost in animals receiving intravenous TPN. Intragastric TPN partially preserved this respiratory immunity.

CONCLUSIONS

Protection against bacterial pneumonia can be induced by prior antigenic immunization. This protection is lost with intravenous TPN, partially preserved with a chemically defined enteral diet, and completely preserved with chow or complex enteral diets. Both route and type of nutrition influence antibacterial respiratory tract immunity.

Endoscopic placement of nasoenteric feeding tubes in critically ill patients: a reliable alternative

Spontaneous transpyloric passage of nasoenteric feeding tubes is often unsuccessful in critically ill patients due to gastric ileus. The purpose of this study was to evaluate the success rate of endoscopic placement of postpyloric nasoenteric tubes and the time required to achieve goal enteral nutritional support in critically ill patients with gastric ileus. Surgical ICU patients with gastric ileus, documented by recorded high gastric residual volumes via a nasogastric tube, were identified for placement of a nasoenteric postpyloric tube via esophagogastroduodenoscopy (EGD). EGD was performed bedside in the ICU, using intravenous sedation, for placement of a 43-inch (109 cm) 8 French tungsten-weighted nasoenteric tube with an inner stylet into the duodenum, and the tube was advanced as far distally as possible. Abdominal radiograph was obtained to confirm final tube position postprocedure. Enteral feedings were initiated immediately with a full-strength formula and increased to the goal enteral feeding rate as tolerated. Thirty-four patients underwent successful placement of postpyloric nasoenteric tubes by EGD. One procedure was aborted in a patient with adult respiratory distress syndrome (ARDS) who developed hypoxemia with gastric insufflation during the EGD. The mean time to achievement of goal enteral nutritional support was 20.8 hours. Tubes remained in place for a range of 6 to 37 days. Endoscopic placement of postpyloric enteral feeding tubes is highly successful, and allows for prompt achievement of goal enteral nutritional requirements. It has two main advantages: it eliminates the risk of patient travel to radiology for fluoroscopic placement, and allows for earlier initiation of enteral feedings because spontaneous passage of weighted nasoenteric tubes into the duodenum in critically ill patients is often unsuccessful.

Are patients fed appropriately according to their caloric requirements?

BACKGROUND

Specific morbidity related to underfeeding and overfeeding necessitates the design of nutrition support regimens that provide calories equal to those required on the basis of energy expenditure. This prospective multicenter trial was designed to determine what percent of patients in long-term acute care facilities receive feeding appropriate to their needs and whether accuracy of feeding has an impact on patient clinical status.

METHODS

Patients on mechanical ventilation who were hospitalized at 32 Vencor Hospitals over a 9-week period and who were receiving only enteral nutrition by continuous infusion at a presumed goal rate were evaluated once by indirect calorimetry (IC) while on feeding. Caloric intake over the preceding 24 hours was determined by physician orders and by patient intake/output (I/O) record. Caloric requirements were defined by measured resting energy expenditure (REE) + 10% for activity. Degree of metabolism was defined by the ratio: (measured REE/Harris-Benedict predicted REE) x 100, and the degree of feeding by the ratio: (calories provided/calories required) x 100.

RESULTS

IC was performed on 335 patients (mean, 11.2 patients per center; range, 1 to 32), of which 72 were excluded for nonphysiological results or failure to achieve steady state, 21 for receiving parenteral nutrition, and 29 for not being on mechanical ventilation at time of testing. The 213 study patients were 58.7% male with mean age 70.1 years (range, 20 to 90 years). Measured REE was <25 kcal/kg in 66.2% of patients and 25 to 35 kcal/kg in 28.6%. Barely half (48.4%) of this patient population was hypermetabolic. Based on physician orders, the majority of patients (58.2%) were overfed, receiving >110% of required calories, and 12.2% were underfed, receiving <90% of requirements. Discrepancies based on I/O records, however, suggested that 36.1% of patients received <90% of those calories ordered. By either basis, only about 25% of patients received feeding within 10% of required calories. The percent of patients being overfed varied between centers, ranging from 32.2% to 92.8%, and was not affected by years of facility IC experience or volume of IC studies per month. The pattern of caloric provision as measured by degree of feeding correlated inversely to degree of metabolism (p < .0001, R2 = .24). Accuracy of feeding had an impact on ventilatory status, as degree of feeding correlated inversely with minute ventilation (p = .001, R2 = .05). Degree of overfeeding also led to significant increases in azotemia (p = .033, R2 = .02). Extrapolating study data over 1 year, reduction in excess volume of enteral formula would have resulted in a cost savings of up to $1.3 million for the Vencor system.

CONCLUSIONS

Because energy expenditure is difficult to predict on the basis of conventional equations, patients in long-term acute care facilities routinely are overfed and underfed, with only 25% receiving calories within 10% of required needs. Measuring a patient's energy requirement at least once by IC is important, because the degree of metabolism predicts how easily a patient will be underfed or overfed. The amount of infused calories should be compared with caloric requirements measured by IC, because the accuracy or degree of underfeeding or overfeeding has an impact on ventilatory status and the likelihood for developing azotemia. Although physician practice or bias may reduce the optimal clinical effect, the use of IC to determine caloric requirements may result in significant cost savings.

Critical care nutrition: routes of feeding

Nutrition is an integral part of the management of the critically ill patient. Nutritional support can be provided by either parenteral or enteral routes. Whenever possible, enteral nutrition is the method of choice, as it reduces complication rates and improves outcome. Potential choices for enteral feeding include nasoesophageal, esophagostomy, gastrostomy, jejunostomy, and transpyloric feeding tubes. The modes of parenteral and enteral nutrition are reviewed individually, including indications and selection of appropriate routes of feeding, methods of tube placement, and benefits and risks associated with each feeding approach.

Immunonutrition in gastric cancer surgical patients

The aim of this study was to evaluate the potential advantages of perioperative versus postoperative administration of an enteral immune-enhancing diet on host defense and protein metabolism. Thirty subjects, candidates for gastrectomy for cancer, were randomly allocated into two groups. The first group (n = 15) received an enteral formula enriched with arginine, omega-3 fatty acids, and RNA 7 d before and 7 d after surgery; the second group (n = 15) received the same diet but only 7 d after surgery. Postoperative immune and inflammatory responses were investigated by phagocytosis ability of polymorphonuclear cells, interleukin-2 receptors (IL-2R), lymphocyte subsets, interleukin-6 (IL-6), and delayed hypersensitivity response (DHR). Prealbumin (PA), retinol binding protein, albumin, and transferrin were determined as protein synthesis indicators. Perioperative immunonutrition prevented the early postoperative impairment of phagocytosis, DHR, total number of lymphocytes, and CD4/CD8 ratio (P < 0.05 versus postoperative group). The IL-2R levels were significantly higher in the perioperative group (P < 0.05 versus postoperative on postoperative day [POD] 4 and 8). Perioperative group also showed lower levels of IL-6 (P < 0.05 versus postoperative on POD 1, 4, and 8) and higher levels of PA (P = 0.04 versus postoperative on POD 8). The perioperative administration of immunonutrition ameliorated the host defense mechanisms, controlled the inflammatory response, and improved the synthesis of short half-life constitutive proteins.

Interventional nutrition for the critical care patient: optimal diets

The classic goals of nutritional support have been to provide for the patient's ongoing nutritional needs and to preserve endogenous tissues from further catabolism. It is becoming increasingly clear that it also is possible to modulate metabolic and pathologic processes through the use of specific nutrients and metabolites and even the route by which nutrition is provided. This article discusses what is and is not known about the nutritional requirements of critically ill dogs and cats and some of the specific nutrients that are being used to enrich formulas for critically ill patients.