Management of short bowel syndrome in infancy
Introduction
The main function of the intestinal tract is to absorb fluids, electrolytes and nutrients to sustain normal metabolic function and enable tissue accretion and growth. Intestinal failure (IF) is the inability to perform this role. There are many potential aetiologies and management is complex including the need for parenteral nutrition (PN) for survival. For epidemiological purposes it is defined as need for parenteral nutrition for more than 27 days.
The term ‘short bowel syndrome’ was used by Irving et al. to describe their patients on long term PN, with a reduction of functional gut mass below the minimum needed for digestion and absorption [1]. Previously with surgical resection being the commonest cause it was defined mainly in terms of length of residual bowel, although bowel quality is clearly relevant in particular the site of gut resected and presence or absence of the ileocaecal valve [2].
The severity of short bowel syndrome can be defined in terms of faecal energy loss, energy absorption being one of the important functions of the gut [3]. Various biological markers have also been proposed to define functional activity of enterocytes. The most promising amongst these is citrulline, a non essential amino acid produced mainly by the enterocytes with plasma concentration shown to correlate with the functional enterocyte mass independently of nutritional and inflammatory status [4].
Over the last few decades the development of parenteral nutrition has revolutionised treatment of IF. The initial attempts to provide intravenous nutrition were with infusion of electrolytes and milk in patients with cholera in 1830s [5]. Over the 20th century there was development of techniques which allowed the addition of various macronutrients including amino acids and fat. In 1968, Dudrick and his co workers were able to demonstrate growth in beagle puppies by providing all nutrition intravenously [6]. Intravenous nutrition was first used in infants with short bowel syndrome in 1967. Since then there has been increasing use with significantly improved outcomes [7]. The development of solid organ transplantation has led to further advances. Transplantation was perfected in dogs by Starzl and Lillehi (Minnesota) who were able to demonstrate that the intestine could tolerate preservation outside the body and would then function adequately following re-implantation [8]. The first long term survivor of small bowel transplant with enteral autonomy was reported in 1990 by Grant [9]. The first child to have small bowel transplant in the UK was in 1993 (Birmingham) and since then there has been a dramatic improvement in outcome with increasing experience of the multidisciplinary medical, surgical and allied health professional team.
Section snippets
Short bowel syndrome
Short bowel syndrome (SBS), where there is insufficient bowel length of sufficient quality for enteral autonomy, is the most common cause of IF in children accounting for 44% of the cases [10]. In a large population-based study, the overall incidence of SBS was 22.1 per 1000 neonatal intensive care unit (NICU) admissions and 24.5 per 100,000 live births, with a much greater prevalence in premature infants. The mortality rate of the condition is high with reported survival rates in paediatric
Necrotizing enterocolitis (NEC)
This is the commonest reason for surgical resection leading to SBS. Incidence varies between 0.3 and 2.4 infants/1000 births and between 7 and 11% amongst infants of less than 1500 g [12]. Factors associated with increased risk include prematurity, low birth weight, formula feeding and associated co morbidities. With increased survival of premature infants, there is an increase in incidence of NEC.
Gastroschisis
This is the second most important case of SBS with an incidence of approximately 2.4 infants per
Predictors of severity and outcome
The various predictors of outcome in children with SBS include (Table 1):
Pathophysiology
The primary defect in SBS is the reduced absorptive surface due to loss of bowel length. There are various mechanisms which affect intestinal function and add to the severity of malabsorption.
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There is a reduction in mucosal brush border hydrolases responsible for carbohydrate digestion and absorption. This potentially results in carbohydrate malabsorption increasing faecal energy loss with undigested carbohydrates causing diarrhoea due to the osmotic effect.
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There is an increased gastric acid
Management of short bowel syndrome
The main aims in management of intestinal failure are
- 1.
Maintaining growth and development
- 2.
Promoting intestinal adaptation
- 3.
Preventing complications.
There are three phases of nutritional management in infants with SBS (Fig. 2) [25].
In the early stages after bowel resection there are increased losses of fluids and electrolytes which can lead to significant electrolyte imbalance and dehydration. Early restoration of fluid and electrolyte homeostasis is therefore required and necessitates aggressive
Practical issues in management of SBS
Management of intestinal failure requires a multidisciplinary team involving paediatricians, nurses, dieticians and pharmacists. Access to a well established nutritional support team has a positive influence on the outcome of these children [27].
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Vascular access — This is dependent on the amount and duration of PN required. Peripherally inserted central lines are very effective means of providing PN over a short to medium term. Infants requiring prolonged duration of PN require more definitive
Enteral nutrition
Choice of feed — It is important to provide a maximum possible proportion of nutrition by the enteral route by choosing a feed that is well tolerated and promotes adaptation.
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There is a paucity of evidence in favouring one type of feed over the other in this setting although breast milk should be used when tolerated as it helps promote adaptation [38].
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In general monomeric feeds that contain predigested proteins, simple carbohydrates and a mix of medium and long chain fatty acids are better
Home parenteral nutrition
In infants who do not need hospitalisation but are dependent on long-term PN, home parenteral nutrition (HPN) is an alternative. HPN can be used for children with irreversible intestinal failure or those who are expected to achieve the transition from PN to full enteral nutrition over weeks to months rather than a shorter time period. Patients eligible for HPN should be in a stable condition.
Intestinal failure associated liver disease
Liver disease is the most frequent and severe complication of IF developing in 40% to 60% of infants. The clinical spectrum includes hepatic steatosis, cholestasis, cholelithiasis, and hepatic fibrosis. Progression to biliary cirrhosis and the development of portal hypertension and liver failure occur in a small proportion.
The aetiology of intestinal failure-associated liver disease (IFALD) is multifactorial and risk factors include [24].
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Prematurity and low birth weight
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Duration of PN
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Underlying
Surgical management of short bowel syndrome
Surgical procedures for short bowel syndrome fall into two categories:
Those designed to prolong intestinal transit time and others to increase functional intestinal absorptive surface area. Transit time can be increased by the following procedures but as there is high risk of serious side effects associated they are not used on regular basis:
- 1.
Anastomosing a reversed segment of small or large bowel in continuity with the small bowel to serve as an antiperistaltic segment
- 2.
Creating recirculating
Intestinal transplantation
Increasing number of children are having intestinal transplantation for irreversible intestinal failure associated with SBS. The main indications for transplant include
- 1.
Intestinal failure liver disease
- 2.
Frequent or life threatening central venous catheter infections
- 3.
Loss of vascular access.
The survival post-transplant has significantly improved over the last 10 years with an increased experience and improved immunosuppression.
Outcome in children with SBS
Outcome in SBS is dependent on many factors including the primary condition leading to resection. There is very little specific outcome data most of which is based on definitions, cohort experience and relatively low numbers. Data available from a single centre in UK showed 91% of children with IF were able to achieve intestinal autonomy by 2 years [48]. Data recorded by aetiology showed that Infants who developed SBS secondary to volvulus were more likely to be weaned off PN than those with SBS
Conclusions
The management of short bowel syndrome is multifaceted and multidisciplinary and presents considerable challenges. There are many aspects of the medical and surgical management which are controversial and difficult. There is a need for clinicians to ensure these rare and complex infants are managed in the best possible environment by multidisciplinary teams and that there is national and international collaboration to ensure individuals get the best possible management through a coordinated and
Conflict of interest
The author has no conflicts of interest to declare.
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