What happens in the intestines

The intestine is a muscular tube lined by cells with an absorptive function. It is divided into two main parts – the small intestine and the large intestine. Most of the processes of digestion and absorption of food take place in the small intestine.

The large intestine’s predominant function is the absorption of water and the fermentation of dietary fibre by gut bacteria, resulting in the production of short chain fatty acids, which are important for colonic health.

An average meal generally consists of fat, protein, carbohydrate and water. Additional ingredients may include electrolytes, eg potassium and sodium, minerals, eg calcium and phosphate, trace elements, for example zinc and selenium and vitamins.

Digestion refers to the process by which ingested food is broken down into components that may be easily absorbed.

Digestion begins in the mouth, where foods are broken down into smaller pieces while also being degraded by chemicals contained in saliva. The partially digested food then passes down the oesophagus into the stomach. In the stomach, partially digested food is combined with acid secreted by the stomach along with enzymes which break down proteins.

After a number of hours the stomach gradually releases liquidised food into the small intestine where it mixes with digestive enzymes secreted by the pancreas and bile produced by the liver resulting in the further degradation of ingested food into simpler dietary components.

These simple dietary components are then exposed to the lining of the small intestine and absorbed into the blood stream where they contribute to a wide variety of the body’s metabolic needs resulting in the maintenance of a normal nutritional state.

What is intestinal failure (IF)?

A large number of diseases affect the intestinal tract of varying severity. A proportion of these diseases may significantly reduce the digestive and absorptive function of the intestine, resulting in weight loss and even profound malnutrition.

The most severe diseases affecting the intestine may result in a syndrome called intestinal failure (IF). IF comprises a group of disorders with many causes, all of which are characterised by an inability to maintain adequate nutrition via the intestines. IF often occurs due to the requirement to surgically remove a large length of diseased small bowel resulting in an insufficient remaining surface area of small bowel to absorb ingested food.

Whatever the cause, patients with IF can only survive with the administration of long-term intravenous feeding with a solution called parenteral nutrition (PN). PN is a synthetic mixture of all the nutrients that the human body requires to maintain a normal nutritional state: water, carbohydrates, protein, fat, minerals electrolytes and vitamins.

Without long-term intravenous feeding patients with IF cannot sustain life. PN must be administered into a large central vein, therefore patients receiving PN require a long-term indwelling catheter, the tip of which usually sits within one of the body’s largest veins.

What is the current situation in the Republic of Ireland for patients with intestinal failure?

Each year in the Republic, there are between 80 and 100 patients with IF, all of whom require highly specialised care. If correctly managed, within a specialist facility, a minority of these patients will avoid a long-term requirement for PN. A majority, however, will require long-term PN, which ideally should be provided in their own home.

These patients, receiving PN at home, continue to require the support of a specialist service to avoid serious complications, including infections, which may result in frequent emergency hospital admissions and even death.

Currently within the Irish healthcare system, there is no specialist service available for IF patients. This means that there is no tertiary referral centre for the highly complex hospitalised patients who develop severe IF each year, nor is there a single specialist unit to manage the existing adult patients receiving PN at home.

In addition, there is no adult unit available to take over the care of paediatric patients with IF ready to transition to adult services from the national paediatric unit at Our Lady's Children's Hospital, Crumlin.

The absence of a specialist IF service in the Republic has been shown to be associated with significantly higher complication rates and hospital admissions for IF patients compared to international data.

There are a significant number of avoidable deaths of IF patients occurring each year due to the lack of specialist services.

The absence of an adult IF unit in the Republic is in stark contrast to the situation on mainland Europe, the United Kingdom and Northern Ireland – there is a 12-bedded IF failure unit in Belfast. IrSPEN is calling on the HSE to immediately establish a dedicated national IF unit in the Republic of Ireland so that this complex and vulnerable patient group can access care which meets minimum international standards and provides them the opportunity to achieve good outcomes from this serious and challenging condition.

IrSPEN (Irish Society for Clinical Nutrition & Metabolism) is holding their bi-annual conference and policy seminar today, March 28th, in Dublin. Nutrition and metabolism in disease management: a new era in medicine will cover key topics such as; tackling complex obesity (prevention vs treatment), the unmet need for Bariatric surgery in Ireland, home enteral nutrition guidelines for Irish patients and a national programme for intestinal failure.