Small bowel review: part I

The effects of long-term total parenteral nutrition on gut mucosal immunity in children with short bowel syndrome: a systematic review

BACKGROUND: Short bowel syndrome (SBS) is defined as the malabsorptive state that often follows massive resection of the small intestine. Most cases originate in the newborn period and result from congenital anomalies. It is associated with a high morbidity, is potentially lethal and often requires months, sometimes years, in the hospital and home on total parenteral nutrition (TPN). Long-term survival without parenteral nutrition depends upon establishing enteral nutrition and the process of intestinal adaptation through which the remaining small bowel gradually increases its absorptive capacity. The purpose of this article is to perform a descriptive systematic review of the published articles on the effects of TPN on the intestinal immune system investigating whether long-term TPN induces bacterial translocation, decreases secretory immunoglobulin A (S-IgA), impairs intestinal immunity, and changes mucosal architecture in children with SBS. METHODS: The databases of OVID, such as MEDLINE and CINAHL, Cochran Library, and Evidence-Based Medicine were searched for articles published from 1990 to 2001. Search terms were total parenteral nutrition, children, bacterial translocation, small bowel syndrome, short gut syndrome, intestinal immunity, gut permeability, sepsis, hyperglycemia, immunonutrition, glutamine, enteral tube feeding, and systematic reviews. The goal was to include all clinical studies conducted in children directly addressing the effects of TPN on gut immunity. RESULTS: A total of 13 studies were identified. These 13 studies included a total of 414 infants and children between the ages approximately 4 months to 17 years old, and 16 healthy adults as controls; and they varied in design and were conducted in several disciplines. The results were integrated into common themes. Five themes were identified: 1) sepsis, 2) impaired immune functions: In vitro studies, 3) mortality, 4) villous atrophy, 5) duration of dependency on TPN after bowel resection. CONCLUSION: Based on this exhaustive literature review, there is no direct evidence suggesting that TPN promotes bacterial overgrowth, impairs neutrophil functions, inhibits blood's bactericidal effect, causes villous atrophy, or causes to death in human model.The hypothesis relating negative effects of TPN on gut immunity remains attractive, but unproven. Enteral nutrition is cheaper, but no safer than TPN. Based on the current evidence, TPN seems to be safe and a life saving solution.

A novel technique of hypothermic luminal perfusion for small bowel preservation

BACKGROUND

This study improved small bowel preservation using University of Wisconsin (UW) solution in conjunction with hypothermic luminal perfusion.

METHODS

Small bowels from Sprague-Dawley rats (n=4) were flushed vascularly with modified UW solution and flushed luminally: group 1, none (clinical control); group 2, UW solution; group 3, 1-hr oxygenated perfusion then static storage with UW; and group 4, 24-hr continuous oxygenated perfusion with UW. Energetics, lipid peroxidation, and histology were assessed during 24 hr at 4 degrees C.

RESULTS

After 12 hr, adenosine triphosphate ranged from 0.5 to 0.8 micromol/g in groups 1 to 3 compared with 1.5 micromol/g in group 4. Even after 24 hr, levels in group 4 were more than twofold greater than levels in groups 1 to 3. Energy charge values ([adenosine triphosphate+adenosine diphosphate/2]/total adenylates) decreased from fresh tissue values of 0.69 in all groups except group 4 throughout 24-hr perfusion. Malondialdehyde (MDA; a product of lipid peroxidation) doubled within 4 hr in group 1 and remained high throughout storage. In groups 3 and 4, MDA levels increased as the time of perfusion increased; group 2 showed no elevated MDA levels at any time. After 12 hr, histologic integrity was superior in groups 3 and 4; however after 24 hr, the best Park's grade was observed in group 3 (median grade 4) compared with groups 1 (grade 7) and 4 (grade 6).

CONCLUSIONS

Our data indicate that perfusion clearly improves tissue energetics; however, mucosal integrity is superior with only a brief 1-hr period of luminal perfusion, despite limited improvements in energetics.