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Enteral feeding is increasingly common in both primary and secondary care and a variety of products can be prescribed. Helen Campbell, Peter Turner and John Sexton give an overview of what enteral nutrition involves, the productsavailable and special considerations needed in enterally-fed patients

Basics of enteral nutrition in adults

In 2008, the British Society for Parenteral andEnteral Nutrition (BAPEN) reported that aquarter of patients admitted to NHS hospitalsand a third of residents admitted to carehomes were malnourished or at a high risk ofbecoming so.1 According to a later report,2

about three million people in the UK aremalnourished or are at risk of becoming so, atan estimated cost of £13 billion fromincreased medical and social services. Forthese people, nutritional support is essentialand, in some cases, will take the form ofparenteral or enteral nutrition.

Parenteral nutrition can meet all the needsof adults unable to be fed by the oral orenteral route over prolonged periods and wasdiscussed in a previous CPD article (PJ, 12September 2009, pp275–8). However, mostmalnourished people have a functioninggastrointestinal tract capable of absorbingnutrients and it is desirable for them to be fedorally or, where needed, enterally (through atube placed into the stomach or jejunum).

Pharmacists will come across enterally fedpatients in hospitals but also, increasingly, inthe community, particularly in care homes.They may be required to dispense feeds(although many are delivered direct to homesby manufacturers) or they might be askedabout the administration of medicines viafeeding tubes.

Indications for enteral feeding Nutritional support is of most benefit inadults who are malnourished (or at risk ofthis) and who are unable to obtain sufficientnutrition from food or drink. Typically thismay be caused by or associated with:

• Anorexia • Dysphagia (often due to diseases of the

oesophagus or neuromuscular disorders, orfollowing stroke, upper gastrointestinal tractsurgery or radiotherapy)

• Malabsorption states (these are common inpatients with inflammatory bowel disease orfollowing some gastrointestinal surgery)

• Chronic vomiting or diarrhoea • Excessive nutrient losses or high demands

for nutrients, such as in cachexia (severemuscle wasting, which is seen in severalmedical conditions) or in patients withpressure sores or open wounds

Malnutrition increases morbidity andmortality from disease, surgery and trauma,and in 2006 the National Institute for Healthand Clinical Excellence published guidancerecommending that all patients admitted tohospital or seen in outpatient departments bescreened for malnutrition.3 This guidance alsodefined malnutrition and being at risk ofmalnutrition (see Panel 1; p2).

Patients with malnutrition or at high risk ofit can be identified by using a screening toolsuch as the BAPEN malnutrition universalscreening tool (MUST; available atwww.bapen.org.uk), which is usually adaptedlocally. This tool is not only based on thepatient’s body mass index but also on anyrecent weight loss and medical conditions.Once a risk is identified, nutritional help andadvice should be given. Oral supplementation,enteral tube feeding or parenteral nutritioncan be considered.

Enteral tube feeding is safer and cheaperthan parenteral feeding. It is preferred if thepatient has adequate gastrointestinalabsorptive capacity because it more closelymimics normal feeding, and healthy gutfunction is more likely to be maintained.Enteral tubes can either be placed through thenose (nasogastric or nasojejunal tube) orthrough the abdominal wall (gastrostomy orjejunostomy tubes). Tubes are usually made ofpolyurethane or silicone, which are notaffected by gastric acid.

Nasogastric and nasojejunal tubes Inhospitals, gastrointestinal access for up to sixweeks is usually achieved using fine-bore (ie,less than 9 French gauge) nasogastric ornasojejunal tubes. These cause less irritation tothe nose and oesophagus (and so present

Evaluate Plan

Reflect

Act

REFLECT1 How is malnutrition defined by the National

Institute for Health and Clinical Excellence? 2 What factors affect the type of nutrition

administered through enteral feeding tubes? 3 How should medicines be administered

through feeding tubes?

Before reading on, think about how this articlemay help you to do your job better.

Alison Young

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fewer gastric reflux risks) than the wider-borePVC tubes (sometimes called Ryles tubes)that are typically used for aspirating gastriccontents, and which are sometimes used forfeeding after aspiration.

Nasogastric tubes administer feed directlyinto the stomach. Surgery or swallowingproblems can lead to reflux or delays in gastricemptying. If gastric feeding is difficult orunsafe (due to a risk of aspiration of gastriccontents) and nasojejunal tubes are used,administering feed past the pyloric sphincterof the stomach.

Higher feeding rates are usually bettertolerated and the use of more concentratedfeeds (eg, over 1.5kcal/ml) is possible usingnasogastric tubes.

The insertion of a nasogastric tube involvespassing the tube (with the end lubricated withwater or KY jelly) through the nostril,pharynx and oesophagus, into the stomach.(The patient is instructed to swallow and thetube is advanced as he or she does so.) Thepositioning of the tube in the stomach isconfirmed by testing the pH of aspirate(usually indicated by a pH less than 5.5,unless the patient is on acid suppressants orantacids). The tube is secured in position withtape and usually goes over the ear. Nasojejunaltubes are inserted with the aid of endoscopy.Metoclopramide has been used to aidinsertion.

PEG and JEJ tubes Where feeding isrequired for longer than six weeks (forexample, because the patient is unlikely torecover his or her ability to feed orally in theshort term), gastrostomy or jejunostomy tubesare used (usually following a patientcompatibility trial with a nasogastric ornasojejunal tube). Gastrostomy orjejunostomy tubes are inserted endoscopicallyor surgically. They are more discreet and, ifcared for properly, are more comfortable forthe patient than nasogastric or nasojejunaltubes.

Typically, a percutaneous endoscopicallyplaced gastrostomy (PEG) tube is insertedthrough the abdominal wall into the patient’sstomach (radiologically inserted gastrostomytubs [RIG] are an alternative). Where post-pyloric feeding is indicated, a jejunostomy(JEJ) tube can be placed into the smallintestine. Like nasojejunal tubes, JEJ tubes areuseful in patients at risk of reflux.

Overall, mortality within a few weeks ofPEG tube placement is high but this is usuallydue to the patient’s condition rather than thetube — PEG tubes are sometimes placed(inappropriately) in patients with poorprognoses (eg, following severe stroke).

Feed administrationFeeds can be given intermittently,continuously or as a bolus. Intermittentinfusion (cycled feeding by gravity or via apump system) over 16 to 20 hours has itsproponents but overnight feeding is alsopossible if the patient is not at risk ofaspiration (a complication of tube feedingwhere feed is inhaled into the lungs, withassociated risks of aspiration pneumonia).

Continuous infusion can also be consideredbut, generally, regimens that more closelymimic normal feeding are preferred. There isconflicting evidence that continuous feedingleads to higher gastric pH levels and bacterialovergrowth.

In nasogastric or gastrostomic feedingintermittent or continuous infusion are notessential but they can prevent “dumping” insome patients, where stomach contents aretransported (dumped) into the small intestinetoo quickly. Common symptoms includeabdominal cramps and nausea but dumpingcan also lead to sudden surges of dextrose inthe blood. Continuous infusion or cycledfeeding is also preferred in patients withinsulin-dependent diabetes, who require asteady availability of carbohydrate.

Bolus feeding involves the administrationof 200–400ml of feed down a PEG tube over15–60 minutes at regular intervals. If a patienthas a fine bore nasogastric tube, an enteralsyringe (these are purple) can be used forbolus feeding but this regimen is time-consuming.

In jejunal feeding, the absence of thestomach to act as a reservoir means thatcontinuous or cycled infusions are essential toavoid dumping syndrome.

As mentioned above, continuous orovernight nasogastric or gastrostomy feeds

should not be given to patients at risk ofaspiration (eg, bed-bound patients). The riskof aspiration of feed in bed-bound patientscan be minimised if the patient is propped upat an angle of 30 degrees or more during andfor 30 minutes after feeding.

Tubes should be flushed before and afterfeeds. Normal water can be used for gastricfeeding but for jejunal feeding, where nostomach acid is involved, some cliniciansrecommend sterile bottled or freshly boiledand cooled water.

In general, tube feeds should not be dilutedand nothing should be added to them becausebacterial contamination of the feed increasesthe risk of infection and can give rise to sepsis,pneumonia and gastrointestinal problems.Closed systems are preferred. Feeds shouldnot be decanted and any feed containersshould be discarded after 24 hours.

Nutrient requirements The 2006 NICE guidance3 recommends thathealthy people should be provided with 25–35kcal/kg/day, including calories from protein.More specifically, protein intake should bebetween 0.8–1.5g/kg per day (ie, 0.13–0.24gnitrogen per kg per day, where 6.25g protein =1g nitrogen).3

In seriously ill or injured people feedingshould be started at no more than 50 per centof their estimated energy and protein needsand be built up to meet full needs over 24 to48 hours. Over-feeding can be risky aftermajor surgery, in septic patients and in multi-organ failure because it can lead tocomplications, such as deranged lipid profile,hyperglycaemia and increased carbon dioxideproduction — these types of patient should bereviewed regularly and underfed until theircondition improves and they become anabolic.This is termed “permissive underfeeding”.

Reduced nutrients (and volumes) areinitially required in patients who have noteaten for over five days, but special starterregimens are unnecessary in patients who havehad a reasonable nutritional intake in theprevious week. Dietitians will assess a patient’snutritional status and history and recommenda regimen taking into account the recipient’sneeds and preferences. Where prolongedmalnutrition has led to a risk of refeedingsyndrome (see below), a maximum of10kcal/kg/day should be used initially and onlyincreased slowly to full needs over four toseven days.

Fluid needs can usually be met by giving30–35ml/kg of body weight per day, butpatients’ needs will vary. For example thosewith an ileostomy will require more fluidsbecause of increased losses via the stoma.

Most feeds contain enough electrolytes tomeet typical daily requirements for sodium,potassium, calcium, magnesium, andphosphate. However, patients withmalnourishment or metabolic stress are oftensalt and water overloaded and normal feedsmay not be appropriate. Too much sodiumcan also be a problem in patients with renal orliver problems, or cardiac failure. On the otherhand, where intestinal losses are excessive,additional sodium may be needed.

Check your

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PANEL 1: NICE CRITERIA FORMALNUTRITION

MalnutritionA person is suffering from malnutrition if he orshe has:

• A body mass index is less than 18.5kg/m2

• Unintentional weight loss greater than 10per cent in three to six months

• A BMI less than 20kg/m2 and unintentionalweight loss greater than 5 per cent in thepast three to six months

Risk of malnutritionA person is at risk of malnutrition if he or she:

• Has eaten little or nothing for more than fivedays

• Is likely to eat little or nothing for five daysor longer

• Has poor absorptive capacity or highnutrient losses

• Has increased nutritional needs, such as incatabolic states

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Monitoring Enteral tube feeding is effective and safe butcarries a number of risks that close monitoringcan prevent. Metabolic complications ofenteral tube feeding, in addition to refeedingsyndrome, include hyperglycaemia, electrolytedisturbances, clotting disturbances andoedema due to fluid overload. (In hospitalfluid balance records and regular body weightare useful when assessing fluid status.)Initially, electrolytes and blood glucose need tobe checked daily, and weekly full blood countsand liver function tests are required until thepatient is stable.

Nasogastric and nasojejunal tubes areeasily displaced so their position should bechecked before each feed (testing tube aspiratewith litmus paper). Gastrostomy andjejunostomy sites should be checked daily,both for tube positioning and infection. Thepatency of tubes should also be checked.

Patients should also be monitored foradverse effects. Gastrointestinal problems,such as bloating and diarrhoea, are common

in enterally fed patients, especially initially,due to dumping or the osmotic load of thefeed, gut atrophy or abnormal motility. Inaddition, the absence of normal eatingmechanisms (eg, chewing) can affect gutmotility and absorption.

Once infective causes are excludedchanging the feed from a standard feed, suchas Jevity, to a semi digested peptide feed, suchas Perative, can help, as can a switch tocontinuous infusion, although this should bechanged to intermittent infusion as soon aspossible.

Sometimes diarrhoea can be helped byhaving breaks of four to eight hours infeeding, or changing to a fibre-containingfeed. Many medicines can cause or aggravatediarrhoea, including H2 blockers, protonpump inhibitors, antibiotics, magnesium-containing antacids, antiarrhythmics,antihypertensives and non-steroidal anti-inflammatory drugs. Antibiotics can affectcolonic flora and reduce short-chain fatty acidproduction from insoluble carbohydrates andfibre. Some liquid medicines contain sorbitol,which has laxative properties, while othershave a high osmolality and can cause osmoticdiarrhoea, especially with jejunaladministration. Pharmacists can advise onalternative products and formulations ifdiarrhoea persists.

A motility agent, such as metoclopramide,may be considered for patients with slowgastric emptying.

Choice of feed Choice of feed is influenced bygastrointestinal absorption or motilityproblems and other co-morbidities, such asrenal or liver disease.

Feeds are prescribable (on FP10, GP10and WP10) for disease-related malnutrition,malabsorption states and dysphagia. Allowedfeeds are listed in appendix 7 of the BritishNational Formulary and prescriptions shouldbe endorsed “ACBS” (ie, AdvisoryCommittee on Borderline Substancesapproved for specific indications). Althoughoral sip feeds (eg, Ensure Plus) do not fit intothe narrow definition of enteral feeding somecan be given through feeding tubes so will alsobe considered in this section.

Enteral and sip feeds provide varyingamounts of nutrients and fluid from differingcombinations of fat, carbohydrate and protein.The variety of feeds available include thosethat are nutritionally complete when given inthe recommended amount, and which be usedas a sole source of nutrition, and those thatprovide calories but lack other essential

More potassium, magnesium andphosphate than normal is needed afterstarvation to restore and maintain stores andplasma levels, and to allow protein synthesis toproceed optimally. More potassium is alsorequired in patients receiving diuretics orinsulin. Hypomagnesaemia due to diuretic-induced excretion, stoma losses, fistulae ordiarrhoea can worsen hypokalaemia.Correcting potassium, magnesium andphosphate deficiencies while feeding canreduce or prevent refeeding problems.

Essential vitamins, minerals and traceelements are required for the prevention orcorrection of deficiency states andmaintenance of normal metabolism andantioxidant status. Standard enteral feedsproviding total daily energy needs containdaily recommended micronutrientrequirements but these may not suffice if thereare increased demands due to illness, pre-existing micronutrient deficits, poorabsorption or when full enteral tube feeding isnot tolerated in the initial period of feeding.

Refeeding syndrome, a set of metaboliccomplications seen when feeding is startedafter prolonged malnutrition due to adepletion of certain electrolytes (especiallyphosphates) and water soluble vitamins, canbe life threatening, resulting in cardiac orrespiratory failure or other problems. NICErecommends the prescription of B vitamins,especially thiamine, when starting feeding inthe very malnourished, along with a gentlestart to nutrition.

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Helen Campbell will be available to answerquestions online on the topic of this articleuntil 9 August 2010

PANEL 2: DISEASE SPECIFIC FEEDS

Malabsorption states Predigested feeds can offer advantages for patients with malabsorptionstates, such as those seen in pancreatic insufficiency or short-bowel syndrome. Nitrogen isprovided as peptide chains or free amino acids but most of the energy is still provided ascarbohydrate and lipid, with the ratio of long and medium chain triglycerides varying betweenbrands. Higher osmolality may lead to increased movement of water into the gut and hence higherstomal losses when prescribed for patients with a short gut and no colon. Semi-digested feedsare also available as peptide-based (oligomeric or semi-elemental) feeds (eg, Peptamen, Perative),containing protein as short peptides (2–50 amino acid chains), and elemental (free amino acid)formulae, such as Elemental 028, containing single amino acids.

Kidney or liver disease Renal patients often require modified electrolyte and restricted volumefeeds, such as Nepro. Liver patients may also need low volume and restricted sodium feeds. Itwas thought that patients with hepatic encephalopathy require reduced protein there is noevidence that this practice is beneficial.

Respiratory disease Designed for use in respiratory failure, high lipid formulae such as Pulmocareor Oxepa provide more than 40 per cent of total energy from lipid. The low carbohydrate to fatratio is intended to minimise carbon dioxide production. Avoidance of overfeeding is moreimportant, however, in limiting respiratory demands.

Critical illness Immune modulating formulae, such as Impact, contain substrates (omega-3 fattyacids, arginine or nucleotides) intended to enhance or attenuate immune function in the criticallyill. These have been shown to reduce septic morbidity and bed stays in upper gastrointestinalsurgery and trauma, but may increase mortality in severe sepsis.

Crohn’s disease Modulen IBD is formulated for patients with Crohn’s disease. Because it isnutritionally complete it can be used as a sole source of nutrition replacing all food and drink forsix to eight weeks. It contains the naturally occurring anti-inflammatory cytokine (TGF-b2) and isthought to reduce inflammation and alter intestinal flora, although its use remains controversial.

Enteral syringe used for bolus feeding (Baxa Ltd)

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components of a complete diet so areintended to be used as supplements.

Nutritionally complete feeds commonlyseen include Ensure Plus and Fortisip andthese are suitable for sip feeding or bolusadministration into the stomach via a PEGtube but are not suitable for jejunal feeding.Jevity and Nutrison are examples of completefeeds used in tube feeding only.

Not all patients who are tube fed areunable to eat. Some may be able to eat smallamounts but need enteral feeding to ensuretheir full nutritional requirements are met (ie,these people may be prescribed enteral feedsin addition to dietary and other oralsupplements). Well known feeds that shouldnot be used as a sole source of nutrition andare intended for use as supplements includeEnsure Plus Juce, Fortijuce, Scandishake andVitasavoury Soups. Calogen is a popular fatemulsion that provides high levels of caloriesbut little else.

Most feeds contain a partially hydrolysedstarch as the carbohydrate source, wholeprotein for nitrogen, and long-chaintriglycerides (LCT) to supply lipid. Energysupply can vary from less than 0.9kcal/ml(low) to more than 1.2kcal/ml (high). Verycalorie dense formulae have recently beenmarketed, providing 2kcal/ml or above andthese benefit patients with fluid restriction,such as in chronic kidney disease or cardiacfailure and for adults with early satiety.

Most feeds are available as fibre-containing or fibre-free, and are generallygluten free. Traditionally, enteral feeds werefibre-free because fibre was thought to causetube obstruction, but the normalrecommended fibre intake of 15 to 30g perday can be provided by the enteral feed. Infact, fermentable (soluble) fibre from guargum, pectin and soy polysaccharides, andnon-fermentable fibre (non-soluble), such asoat fibre, are beneficial to maintain gutphysiology, prevent diarrhoea and

constipation, and for glycaemic and lipidcontrol. Fermentable fibre is broken down toshort-chain fatty acids in the colon.

More recently, oligosaccharides, such asinulin, and fructo/galacto-oligosaccharides, arebeing introduced to feed formulations becausethey are also metabolised by gut bacteria,resulting in improved gastrointestinalfunction.

Many feeds are described as “clinicallylactose free”, containing less than 1g lactoseper 100ml of formula. These are suitable forpatients with primary or secondary lactasedeficiency (caused by gut damage due toinflammation, infection, short bowel or rapidsmall bowel transit time) where malabsorptionof lactose would cause diarrhoea.

Soya protein formulae are available forpatients with intolerance to dairy products.

The long-chain omega-3 fatty acids DHA(docosahexaenoic acid) and EPA(eicosapentanoic acid) present in oily fishhave been linked with health — particularlycardiovascular — benefits. Increasing omega-3intake may also have a role in the preventionof dementia. Feeds that include fish oils intheir formulation are now available. Panel 2(p3) describes some disease specific feeds.

There is an increasing range of nutritionalproducts available. These impose a significantacquisition cost implication on purchasers andfor this and clinical reasons patients should beassessed by a dietitian or experienced healthprofessional before and while receiving enteralnutrition in order that only appropriateproducts and quantities are prescribed. Forpatients requiring a vegan or religious diet, thesuitability of individual products should beconfirmed with manufacturers.

When patients are discharged fromhospital on continuing enteral tube feeding,care must be taken to ensure that thearrangements for the supply of feeds andequipment is in place and that all carers arefully informed. Whether the feeds are intendedfor bolus or infusion administration needs tobe specified. Although enteral feeding isusually started in secondary care, GPs canalso refer patients for placement of feedingtubes. Patients are managed by a communitydietitians and may be followed up by hospitalnutrition teams as outpatients. Health careprofessionals should also be aware of thepotential impact of tube feeding on the eatinghabits of carers, who may not botherpreparing proper meals, if they are justcooking for themselves.

MedicinesPharmacists may be asked to advise on theadministration of medicines via feeding tubesas well as possible interactions between drugsand feeds.

Most medicines are not licensed foradministration through enteral tubes. Ingeneral, medicines administered via an enteralfeed tube should be given separate from thefeed, flushing the tube with water before andafter each medicine and only used afterestablishing compatibility with the feed.

The much-reduced bioavailability ofphenytoin is the best known example among

many drug-feed interactions and feed shouldbe stopped for two hours before phenytoin isgiven. Some advice is based onrecommendations given with productsdispensed for oral use so, for example,tetracycline should not be given with milkyfeeds and if penicillin is given, feeds should bestopped for an hour before and after dosing(see Resources for further details).

Dispersible tablets, elixirs or suspensionsare preferable to syrups because of the effectsof high osmolality (eg, diarrhoea).

Blockage of tubes is common if adequateflushing is not performed after eachadministration of both feed and eachmedicine. Crushed tablets, potassium, ironsupplements and sucralfate are particularlylikely to cause blockage problems. Unblockingcan be attempted (usually by nursing staff) byflushing with warm water or an alkalinesolution of pancreatic enzymes, but sometimestubes will need to be replaced.

Summary With an increasing awareness of the potentialmorbidity, mortality, and financial burdensassociated with malnutrition, enteral and oralsip feeds are being increasingly used based ona strong evidence and NICErecommendations. A general knowledge ofenteral feeding is, therefore, of value topharmacists.

Resources•“The handbook of drug administration viaenteral feeding tubes” (R White et al,Pharmaceutical Press) is a practical guide to thesafe administration of medicines via enteralfeeding tubes. It includes information on drugtherapy review, medication formulation choiceand unlicensed medication use as well asguidance on the safe administration of specificdrugs and formulations.

References1 Russell CA, Elia M. Nutrition screening survey inthe UK in 2008. British Association forParenteral and Enteral Nutrition (BAPEN), 2008.

2 Combating Malnutrition: Recommendations forAction BAPEN 2009.

3 Nutrition support in adults. NICE ClinicalGuideline 32, 2006.

CPD articles are commissioned by ThePharmaceutical Journal and are not peerreviewed.

PRACTICE POINTSReading is only one way to undertake CPDand the regulator will expect to see variousapproaches in a pharmacist’s CPD portfolio.

1 Familiarise yourself with sections 7.1 to 7.4of appendix 7 in the British NationalFormulary. Consider typical indications forpatients to be receiving enteral or oralnutrition.

2 Discuss with a colleague what you wouldconsider if asked to recommend amedicine for administration via an enteralfeeding tube.

3 Make sure you can describe thedifferences between the various enteraland oral feeds and supplements available.

Consider making this activity one of your nineCPD entries this year.

Authors

Helen Campbell, DipClinPharm,MRPharmS, is senior pharmacist fornutrition and surgical services, and PeterTurner, MSc, RD, is specialist dietitian fornutritional support at the Royal Liverpooland Broadgreen University Hospitals NHSTrust. John Sexton, MSc, MRPharmS, isprincipal pharmacist lecturer-practitioner atthe Royal Liverpool and BroadgreenUniversity Hospitals NHS Trust andLiverpool John Moores University.

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