Insulin secretion and sensitivity in children on cyclic total parenteral nutrition

Prevention of complications for hospitalized patients receiving parenteral nutrition: A narrative review

Hospitalized patients may benefit from parenteral nutrition to address their compromised nutrition status attributed to limited oral/enteral intake and increased nutrient/energy requirement during acute illness. Parenteral nutrition, however, can be associated with many complications that can negatively impact patient outcomes. In this review, we focus on potential metabolic and catheter-related complications associated with parenteral nutrition use. We report on potential risk factors for such complications and highlight strategies for prevention and early recognition. To optimize outcomes, key findings include the creation and implementation of evidence-based protocols with proven efficacy. For each hospital unit delivering parenteral nutrition to patients, tracking compliance with established protocols and patient outcomes is crucial for ongoing improvement through identification of gaps, proper reeducation and training, and ongoing refinement of care protocols. Establishment of specialized inpatient nutrition support teams should be considered.

Glucose Metabolism and Stress Hyperglycemia in Critically Ill Children

Abnormalities in glucose metabolism and stress hyperglycemia (SH) are commonly seen in critically ill children. While SH may represent an adaptive stress response as a source of fuel for the body during the "fight or flight response" of critical illness, several studies have observed the association of SH with worse outcomes in different disease states. In addition to alterations in glucose metabolism and acquired insulin resistance from inflammation and organ dysfunction, specific intensive care unit (ICU) interventions can also affect glucose homeostasis and SH during critical illness. Common ICU interventions can mediate the development of SH in critical illness. The strategy of tight glucose control combined with intensive insulin therapy (TGC-IIT) has been well studied to improve outcomes in both adult and pediatric critical illness. Though early single-center studies of TGC-IIT observed benefits with better outcomes albeit with greater incidence of hypoglycemia, subsequent larger multicenter studies in both children and adults have not conclusively demonstrated benefits and have even observed harm. Several possible reasons for these contrasting results include differences in patient populations, glycemic control targets, and glucose control protocols including nutrition support, and variability in achieving these targets, measurement methods, and expertise in protocol implementation. Future studies may need to individualize management of SH in critically ill children with improved monitoring of indices of glycemia utilizing continuous sensors and closed-loop insulin administration.

A prospective case-control pilot study to evaluate bone microarchitecture in children and teenagers on long-term parenteral nutrition using HR-pQCT

Long-term parenteral nutrition (PN) may induce bone complications. Tridimensional bone imaging techniques such as high-resolution peripheral quantitative computed tomography (HR-pQCT) allow the assessment of both compartmental volumetric densities and microarchitecture. Our aim was to evaluate these parameters in children and teenagers receiving long-term PN. This cross-sectional, case–control study included children older than 9 years undergoing PN for at least 2 years. They were age-, gender- and puberty-matched with healthy controls (1:2). Evaluation included biological assessment of bone metabolism (serum calcium, phosphate, and albumin; urinary calcium and creatinine; 25-OH vitamin D, osteocalcin and PTH), dual X-ray absorptiometry (DXA) and HR-pQCT at the ultradistal tibia and radius. Results are presented as median [range]. Eleven patients (3 girls) with a median age of 16 [9–19] years were included. Bone parameters assessed by HR-pQCT at the ultradistal radius and tibia were similar in patients and controls. Parathyroid hormone (PTH) levels were higher (14 [7–115] vs 16 [12–27]) and osteocalcin levels were lower (44 [15–65] vs 65 [38–142]) in patients than in controls, although within the normal range. Conclusions: there were no differences for compartmental bone densities and microarchitecture in patients undergoing chronic PN. Further longitudinal studies are required to confirm these quite reassuring preliminary results.

Nutrition Support and Tight Glucose Control in Critically Ill Children: Food for Thought!

Numerous studies have examined the strategy of tight glucose control (TGC) with intensive insulin therapy (IIT) to improve clinical outcomes in critically ill adults and children. Although early studies of TGC with IIT demonstrated improved outcomes at the cost of elevated hypoglycemia rates, subsequent studies in both adults and children have not demonstrated any benefit from such a strategy. Differences in patient populations, variable glycemic targets, and glucose control protocols, inconsistency in attaining these targets, heterogeneous intermittent sampling, and measurement techniques, and variable expertise in protocol implementation are possible reasons for the contrasting results from these studies. Notably, differences in modes of nutrition support may have also contributed to these disparate results. In particular, combined use of early parenteral nutrition (PN) and a strategy of TGC with IIT may be associated with improved outcomes, while combined use of enteral nutrition (EN) and a strategy of TGC with IIT may be associated with equivocal or worse outcomes. This article critically examines published clinical trials that have employed a strategy of TGC with IIT in critically ill children to highlight the role of EN vs. PN in influencing clinical outcomes including efficacy of TGC, and adverse effects such as occurrence of hypoglycemia and hospital acquired infections. The perspective afforded by this article should help practitioners consider the potential importance of mode of nutrition support in impacting key clinical outcomes if they should choose to employ a strategy of TGC with IIT in critically ill children with hyperglycemia.

Renal consequences of parenteral nutrition

Parenteral nutrition (PN) can be described as the "Intravenous administration of nutrients necessary to sustain life in those who would otherwise have died or suffered serious disease". PN is indicated in children who cannot be fully fed by the oral or intestinal route, usually as a result of intestinal failure. Intradialytic parenteral nutrition (IDPN) is rarely indicated in children on dialysis and does not confer a benefit over enteral supplements in the compliant patient with adequate intestinal function. Renal and metabolic consequences of PN are potentially life-threatening and include disorders of glucose homeostasis, acid-base and fluid and electrolyte disturbances, nephrolithiasis, impaired renal function and metabolic bone disease. Many of these complications are avoidable. Adequate clinical and biochemical assessment and monitoring of children receiving PN by a multidisciplinary nutrition support team is recommended to mitigate against the risks of these complications.

Stress hyperglycemia in pediatric critical illness: the intensive care unit adds to the stress!

Stress hyperglycemia (SH) commonly occurs during critical illness in children. The historical view that SH is beneficial has been questioned in light of evidence that demonstrates the association of SH with worse outcomes. In addition to intrinsic changes in glucose metabolism and development of insulin resistance, specific intensive care unit (ICU) practices may influence the development of SH during critical illness. Mechanical ventilation, vasoactive infusions, renal replacement therapies, cardiopulmonary bypass and extracorporeal life support, therapeutic hypothermia, prolonged immobility, nutrition support practices, and the use of medications are all known to mediate development of SH in critical illness. Tight glucose control (TGC) to manage SH has emerged as a promising therapy to improve outcomes in critically ill adults, but results have been inconclusive. Large variations in ICU practices across studies likely resulted in inconsistent results. Future studies of TGC need to take into account the impact of commonly used ICU practices and, ideally, standardize protocols in an attempt to improve the accuracy of conclusions from such studies.

Lower insulin secretory response to glucose induced by artificial nutrition in children: prolonged and total parenteral nutrition

Long-term parenteral nutrition (TPN) in children is associated with sustained hyperinsulinemia due to a high nutriment infusion flow 12 h/24 h, with plausible lipotoxicity secondary to repeated lipid infusions and with changes in incretin hormone release. The aim of this study was to test whether long-term TPN can lead to an alteration in beta-cell function. Thirteen children (age 9.5 +/- 3.9 y) on total TPN without obvious alternation in glucose tolerance were included. beta-Cell function was quantified with an intravenous glucose tolerance test (IVGTT) and a graded glucose infusion. First phase insulin release (FPIR) was low in five patients. The same demonstrated a lower insulin release under graded glucose infusion, although plasma glucose reached values as high as 15 mM. These data emphasize that metabolic conditions induced by TPN can lead to lower insulin secretory response to glucose. Patients who remain dependent on TPN are at risk of developing glucose tolerance disorders.

Short bowel syndrome and intestinal transplantation in children

PURPOSE OF REVIEW

This review summarizes recent knowledge and clinical practice for pediatric patients suffering extensive intestinal resection causing short bowel syndrome. This condition requires the use of parenteral nutrition, as long as intestinal failure persists, and may be, in some selected cases, an indication for intestinal transplantation.

RECENT FINDINGS

Biological evaluation of intestinal failure is becoming possible with the use of plasma citrulline as a marker of intestinal mass. Few epidemiological data are available; some indicate an increased incidence of short bowel syndrome-related gastroschisis and persistent high incidence of necrotizing enterocolitis. Morbidity and mortality data in pediatric patients with short bowel syndrome are limited, while long-term outcome is better documented from recently reported cohorts. Non-transplant surgery is one of the best options for patients with unadapted short bowel syndrome. Isolated liver transplantation may be avoided. The use of trophic factors for enhancing mucosal hyperplasia still remains disappointing.

SUMMARY

The management should include therapies adapted to each stage of intestinal failure, based on a multidisciplinary approach in centers involving pediatric surgery, pediatric gastroenterology, parenteral nutrition expertise, home-parenteral nutrition program, and liver-intestinal transplantation experience. If managed appropriately, the prognosis of short bowel syndrome is excellent, with limited indications for intestinal and/or liver transplantation. Timing for patient referral in specialized centers remains an issue.

Causes and management of intestinal failure in children

Intestinal failure is a condition requiring the use of parenteral nutrition as long as it persists. Causes of severe protracted intestinal failure include short bowel syndrome, congenital diseases of enterocyte development, and severe motility disorders (total or subtotal aganglionosis or chronic intestinal pseudo-obstruction syndrome). Intestinal failure may be irreversible in some patients, thus requiring permanent parenteral nutrition. Liver disease may develop with subsequent end-stage liver cirrhosis in patients with intestinal failure as a consequence of both underlying digestive disease and unadapted parenteral nutrition. Death will occur if combined liver-intestine transplantation is not performed. Catheter-related sepsis and/or extensive vascular thrombosis may impede the continuation of a safe and efficient parenteral nutrition and may also require intestinal transplantation in some selected cases. Thus management of patients with intestinal failure requires an early recognition of the condition and the analysis of its risk of irreversibility. Timing of referral for intestinal transplantation remains a crucial issue. As a consequence, management should include therapies adapted to each stage of intestinal failure based on a multidisciplinary approach in centers involving pediatric gastroenterology, parenteral nutrition expertise, home parenteral nutrition program, pediatric surgery, and liver intestinal transplantation program.

Irreversible intestinal failure

Intestinal failure (IF) can be defined as the reduction of functional gut mass below the minimal amount necessary for digestion and absorption adequate to satisfy the nutrient and fluid requirements for maintenance in adults or growth in children. In developed countries, IF mainly includes individuals with the congenital or early onset of conditions requiring protracted or indefinite parenteral nutrition (PN). Short bowel syndrome was the first commonly recognized cause of protracted IF. The normal physiologic process of intestinal adaptation after extensive resection usually allows for recovery of sufficient intestinal function within weeks to months. During this time, patients can be sustained on parenteral nutrition. Only a few children have permanent intestinal insufficiency and life-long dependency on PN. Non-transplant surgery including small bowel tapering and lengthening may allow weaning from PN in some cases. Hormonal therapy with recombinant human growth hormone has produced poor results while therapy with glucagon-like peptide-2 holds promise. Congenital diseases of enterocyte development such as microvillus inclusion disease or intestinal epithelial dysplasia cause permanent IF for which no curative medical treatment is currently available. Severe and extensive motility disorders such as total or subtotal intestinal aganglionosis (long segment Hirschsprung disease) or chronic intestinal pseudo-obstruction syndrome may also cause permanent IF. PN and home-PN remain are the mainstays of therapy regardless of the cause of IF. Some patients develop complications while receiving long-term PN for IF especially catheter related complications (thrombosis, sepsis) and liver disease. These patients may be candidates for intestinal transplantation. This review discusses the causes of irreversible IF and emphasizes the specific medico-surgical strategies for prevention and treatment of these conditions at several stages of IF.