Department of Child Health, King's College Hospital, London, United Kingdom

Abstract

Intestinal failure (IF) occurs when the body is unable to sustain its energy and fluid requirements without support, due to loss of functional small bowel. Prolonged IF is seen after large intestinal resection and described as short bowel syndrome (SBS). The hallmark of the management is parental nutrition (PN), which is costly and may be associated with the well-recognized problems of parental nutrition associated liver disease (PNALD) and line related sepsis. Cessation of PN at the earliest possible stage is desirable but for this enteral autonomy has to be achieved first. Intestinal adaptation occurs when the remaining gut goes through morphological changes increasing its absorptive capacity. Factors such as intraluminal nutrients, gastrointestinal secretions and hormones facilitate adaptation. Enteral feeds are a potent stimulant to adaptation, and should be started as soon as the clinical situation permits. Some drugs are thought to increase intestinal adaptation. These include glutamine, growth hormone and glucagon like peptide- 2, but there is a paucity of pediatric data to guide their use. In some cases surgical bowel lengthening procedures can be performed to increase the absorptive surface area. An isolated liver transplantation may be required if the liver has sustained irreversible damage but intestinal autonomy seems achievable. When prolonged PN is either unsustainable or associated with unacceptable side effects, small bowel transplantation should be considered as a treatment option.

Keywords: Intestinal failure; Short bowel syndrome; Intestinal adaptation; Parenteral nutrition

Intestinal failure (IF) is defined as the reduction of functional small bowel mass and absorptive surface area below a minimum needed for absorption of nutrients and fluids to maintain baseline energy requirements, fluid requirements and electrolyte homeostasis. In simpler terms it is the inability to maintain nutritional and fluid balance without support. A transient and usually reversible form of IF is commonly seen in gastroenteritis. Infective diarrhea is the commonest form of IF in the developing world. A variety of diseases cause prolonged IF and despite different pathophysiology they have a requirement for treatment with parenteral nutrition (PN) in common.

Causes for prolonged IF are large intestinal resection, congenital enterocyte abnormalities such as microvillous inclusion disease and gastrointestinal motility disorders such as long segment Hirschsprung's disease or intestinal pseudo-obstruction syndrome.[1] The entity of IF after intestinal resection is referred to as short bowel syndrome (SBS). The underlying processes leading to intestinal resection are many. These include antenatal problems such as intestinal atresias, abdominal wall defects such as gastroschisis, malrotation and volvulus and necrotizing enterocolitis (NEC) in the neonatal period, predominantly in premature infants.

There are different definitions of SBS. Some are based on the need for intervention, for example PN dependency for more than 1- 3 months post resection. Other definitions are based on residual bowel length. For instance, a residual small bowel length of less than 25% of the expected for age and gestation is considered as SBS.[2] A working group studying Canadian neonatal units has estimated the incidence of SBS as 1 per 4000 live births and the mortality rate as 37.5 %.[3] The major predictors for mortality are PN associated liver disease and length of remaining small intestine.[4] The aim in the management of IF is to achieve intestinal autonomy. For this the gut remnant undergoes changes to compensate for the loss of absorptive surface area known as intestinal adaptation. Positive predicting factors of achieving intestinal autonomy and successfully weaning PN are generally said to be the age- adjusted percentage of the remaining small bowel and the presence of the ileocecal valve (ICV).