Download basics of enteral nutrition in adults

PJ, LandD online only July 2010_Layout 1 7/15/2010 11:46 AM Page 1
PJ Online 1
CPD
Basics of enteral nutrition in adults
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 products
available and special considerations needed in enterally-fed patients
Reflect
Plan
Evaluate
Act
REFLECT
1 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 article
may help you to do your job better.
Alison Young
In 2008, the British Society for Parenteral and
Enteral Nutrition (BAPEN) reported that a
quarter of patients admitted to NHS hospitals
and a third of residents admitted to care
homes were malnourished or at a high risk of
becoming so. 1 According to a later report,2
about three million people in the UK are
malnourished or are at risk of becoming so, at
an estimated cost of £13 billion from
increased medical and social services. For
these people, nutritional support is essential
and, in some cases, will take the form of
parenteral or enteral nutrition.
Parenteral nutrition can meet all the needs
of adults unable to be fed by the oral or
enteral route over prolonged periods and was
discussed in a previous CPD article (PJ, 12
September 2009, pp275–8). However, most
malnourished people have a functioning
gastrointestinal tract capable of absorbing
nutrients and it is desirable for them to be fed
orally or, where needed, enterally (through a
tube placed into the stomach or jejunum).
Pharmacists will come across enterally fed
patients in hospitals but also, increasingly, in
the community, particularly in care homes.
They may be required to dispense feeds
(although many are delivered direct to homes
by manufacturers) or they might be asked
about the administration of medicines via
feeding tubes.
Indications for enteral feeding
Nutritional support is of most benefit in
adults who are malnourished (or at risk of
this) and who are unable to obtain sufficient
nutrition from food or drink. Typically this
may be caused by or associated with:
• Anorexia
• Dysphagia (often due to diseases of the
oesophagus or neuromuscular disorders, or
following stroke, upper gastrointestinal tract
surgery or radiotherapy)
• Malabsorption states (these are common in
patients with inflammatory bowel disease or
following some gastrointestinal surgery)
• Chronic vomiting or diarrhoea
• Excessive nutrient losses or high demands
for nutrients, such as in cachexia (severe
muscle wasting, which is seen in several
medical conditions) or in patients with
pressure sores or open wounds
Malnutrition increases morbidity and
mortality from disease, surgery and trauma,
and in 2006 the National Institute for Health
and Clinical Excellence published guidance
recommending that all patients admitted to
hospital or seen in outpatient departments be
screened for malnutrition.3 This guidance also
defined malnutrition and being at risk of
malnutrition (see Panel 1; p2).
Patients with malnutrition or at high risk of
it can be identified by using a screening tool
such as the BAPEN malnutrition universal
screening tool (MUST; available at
www.bapen.org.uk), which is usually adapted
locally. This tool is not only based on the
patient’s body mass index but also on any
recent weight loss and medical conditions.
Once a risk is identified, nutritional help and
advice should be given. Oral supplementation,
enteral tube feeding or parenteral nutrition
can be considered.
Enteral tube feeding is safer and cheaper
than parenteral feeding. It is preferred if the
patient has adequate gastrointestinal
absorptive capacity because it more closely
mimics normal feeding, and healthy gut
function is more likely to be maintained.
Enteral tubes can either be placed through the
nose (nasogastric or nasojejunal tube) or
through the abdominal wall (gastrostomy or
jejunostomy tubes). Tubes are usually made of
polyurethane or silicone, which are not
affected by gastric acid.
Nasogastric and nasojejunal tubes In
hospitals, gastrointestinal access for up to six
weeks is usually achieved using fine-bore (ie,
less than 9 French gauge) nasogastric or
nasojejunal tubes. These cause less irritation to
the nose and oesophagus (and so present
July 2010
www.pjonline.com
PJ, LandD online only July 2010_Layout 1 7/15/2010 11:46 AM Page 2
2 PJ Online
Learning & development
fewer gastric reflux risks) than the wider-bore
PVC tubes (sometimes called Ryles tubes)
that are typically used for aspirating gastric
contents, and which are sometimes used for
feeding after aspiration.
Nasogastric tubes administer feed directly
into the stomach. Surgery or swallowing
problems can lead to reflux or delays in gastric
emptying. If gastric feeding is difficult or
unsafe (due to a risk of aspiration of gastric
contents) and nasojejunal tubes are used,
administering feed past the pyloric sphincter
of the stomach.
Higher feeding rates are usually better
tolerated and the use of more concentrated
feeds (eg, over 1.5kcal/ml) is possible using
nasogastric tubes.
The insertion of a nasogastric tube involves
passing the tube (with the end lubricated with
water or KY jelly) through the nostril,
pharynx and oesophagus, into the stomach.
(The patient is instructed to swallow and the
tube is advanced as he or she does so.) The
positioning of the tube in the stomach is
confirmed by testing the pH of aspirate
(usually indicated by a pH less than 5.5,
unless the patient is on acid suppressants or
antacids). The tube is secured in position with
tape and usually goes over the ear. Nasojejunal
tubes are inserted with the aid of endoscopy.
Metoclopramide has been used to aid
insertion.
PEG and JEJ tubes Where feeding is
required for longer than six weeks (for
example, because the patient is unlikely to
recover his or her ability to feed orally in the
short term), gastrostomy or jejunostomy tubes
are used (usually following a patient
compatibility trial with a nasogastric or
nasojejunal tube). Gastrostomy or
jejunostomy tubes are inserted endoscopically
or surgically. They are more discreet and, if
cared for properly, are more comfortable for
the patient than nasogastric or nasojejunal
tubes.
Typically, a percutaneous endoscopically
placed gastrostomy (PEG) tube is inserted
through the abdominal wall into the patient’s
stomach (radiologically inserted gastrostomy
tubs [RIG] are an alternative). Where postpyloric feeding is indicated, a jejunostomy
(JEJ) tube can be placed into the small
intestine. Like nasojejunal tubes, JEJ tubes are
useful in patients at risk of reflux.
Overall, mortality within a few weeks of
PEG tube placement is high but this is usually
due to the patient’s condition rather than the
tube — PEG tubes are sometimes placed
(inappropriately) in patients with poor
prognoses (eg, following severe stroke).
PANEL 1: NICE CRITERIA FOR
MALNUTRITION
Malnutrition
A person is suffering from malnutrition if he or
she has:
• A body mass index is less than 18.5kg/m2
• Unintentional weight loss greater than 10
per cent in three to six months
• A BMI less than 20kg/m2 and unintentional
weight loss greater than 5 per cent in the
past three to six months
Risk of malnutrition
A person is at risk of malnutrition if he or she:
• Has eaten little or nothing for more than five
days
• Is likely to eat little or nothing for five days
or longer
• Has poor absorptive capacity or high
nutrient losses
• Has increased nutritional needs, such as in
catabolic states
Continuous infusion can also be considered
but, generally, regimens that more closely
mimic normal feeding are preferred. There is
conflicting evidence that continuous feeding
leads to higher gastric pH levels and bacterial
overgrowth.
In nasogastric or gastrostomic feeding
intermittent or continuous infusion are not
essential but they can prevent “dumping” in
some patients, where stomach contents are
transported (dumped) into the small intestine
too quickly. Common symptoms include
abdominal cramps and nausea but dumping
can also lead to sudden surges of dextrose in
the blood. Continuous infusion or cycled
feeding is also preferred in patients with
insulin-dependent diabetes, who require a
steady availability of carbohydrate.
Bolus feeding involves the administration
of 200–400ml of feed down a PEG tube over
15–60 minutes at regular intervals. If a patient
has a fine bore nasogastric tube, an enteral
syringe (these are purple) can be used for
bolus feeding but this regimen is timeconsuming.
In jejunal feeding, the absence of the
stomach to act as a reservoir means that
continuous or cycled infusions are essential to
avoid dumping syndrome.
As mentioned above, continuous or
overnight nasogastric or gastrostomy feeds
Feed administration
Feeds can be given intermittently,
continuously or as a bolus. Intermittent
infusion (cycled feeding by gravity or via a
pump system) over 16 to 20 hours has its
proponents but overnight feeding is also
possible if the patient is not at risk of
aspiration (a complication of tube feeding
where feed is inhaled into the lungs, with
associated risks of aspiration pneumonia).
July 2010
www.pjonline.com
Check your
learning
available online until 16 August 2010
w w w. p j o n l i n e . c o m
should not be given to patients at risk of
aspiration (eg, bed-bound patients). The risk
of aspiration of feed in bed-bound patients
can be minimised if the patient is propped up
at an angle of 30 degrees or more during and
for 30 minutes after feeding.
Tubes should be flushed before and after
feeds. Normal water can be used for gastric
feeding but for jejunal feeding, where no
stomach acid is involved, some clinicians
recommend sterile bottled or freshly boiled
and cooled water.
In general, tube feeds should not be diluted
and nothing should be added to them because
bacterial contamination of the feed increases
the risk of infection and can give rise to sepsis,
pneumonia and gastrointestinal problems.
Closed systems are preferred. Feeds should
not be decanted and any feed containers
should be discarded after 24 hours.
Nutrient requirements
The 2006 NICE guidance3 recommends that
healthy people should be provided with 25–
35kcal/kg/day, including calories from protein.
More specifically, protein intake should be
between 0.8–1.5g/kg per day (ie, 0.13–0.24g
nitrogen per kg per day, where 6.25g protein =
1g nitrogen).3
In seriously ill or injured people feeding
should be started at no more than 50 per cent
of their estimated energy and protein needs
and be built up to meet full needs over 24 to
48 hours. Over-feeding can be risky after
major surgery, in septic patients and in multiorgan failure because it can lead to
complications, such as deranged lipid profile,
hyperglycaemia and increased carbon dioxide
production — these types of patient should be
reviewed regularly and underfed until their
condition improves and they become anabolic.
This is termed “permissive underfeeding”.
Reduced nutrients (and volumes) are
initially required in patients who have not
eaten for over five days, but special starter
regimens are unnecessary in patients who have
had a reasonable nutritional intake in the
previous week. Dietitians will assess a patient’s
nutritional status and history and recommend
a regimen taking into account the recipient’s
needs and preferences. Where prolonged
malnutrition has led to a risk of refeeding
syndrome (see below), a maximum of
10kcal/kg/day should be used initially and only
increased slowly to full needs over four to
seven days.
Fluid needs can usually be met by giving
30–35ml/kg of body weight per day, but
patients’ needs will vary. For example those
with an ileostomy will require more fluids
because of increased losses via the stoma.
Most feeds contain enough electrolytes to
meet typical daily requirements for sodium,
potassium, calcium, magnesium, and
phosphate. However, patients with
malnourishment or metabolic stress are often
salt and water overloaded and normal feeds
may not be appropriate. Too much sodium
can also be a problem in patients with renal or
liver problems, or cardiac failure. On the other
hand, where intestinal losses are excessive,
additional sodium may be needed.
PJ, LandD online only July 2010_Layout 1 7/15/2010 11:46 AM Page 3
PJ Online 3
CPD
PANEL 2: DISEASE SPECIFIC FEEDS
Malabsorption states Predigested feeds can offer advantages for patients with malabsorption
states, such as those seen in pancreatic insufficiency or short-bowel syndrome. Nitrogen is
provided as peptide chains or free amino acids but most of the energy is still provided as
carbohydrate and lipid, with the ratio of long and medium chain triglycerides varying between
brands. Higher osmolality may lead to increased movement of water into the gut and hence higher
stomal losses when prescribed for patients with a short gut and no colon. Semi-digested feeds
are 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 volume
feeds, such as Nepro. Liver patients may also need low volume and restricted sodium feeds. It
was thought that patients with hepatic encephalopathy require reduced protein there is no
evidence that this practice is beneficial.
Respiratory disease Designed for use in respiratory failure, high lipid formulae such as Pulmocare
or Oxepa provide more than 40 per cent of total energy from lipid. The low carbohydrate to fat
ratio is intended to minimise carbon dioxide production. Avoidance of overfeeding is more
important, however, in limiting respiratory demands.
Critical illness Immune modulating formulae, such as Impact, contain substrates (omega-3 fatty
acids, arginine or nucleotides) intended to enhance or attenuate immune function in the critically
ill. These have been shown to reduce septic morbidity and bed stays in upper gastrointestinal
surgery and trauma, but may increase mortality in severe sepsis.
Crohn’s disease Modulen IBD is formulated for patients with Crohn’s disease. Because it is
nutritionally complete it can be used as a sole source of nutrition replacing all food and drink for
six to eight weeks. It contains the naturally occurring anti-inflammatory cytokine (TGF-b2) and is
thought to reduce inflammation and alter intestinal flora, although its use remains controversial.
in enterally fed patients, especially initially,
due to dumping or the osmotic load of the
feed, gut atrophy or abnormal motility. In
addition, the absence of normal eating
mechanisms (eg, chewing) can affect gut
motility and absorption.
Once infective causes are excluded
changing the feed from a standard feed, such
as Jevity, to a semi digested peptide feed, such
as Perative, can help, as can a switch to
continuous infusion, although this should be
changed to intermittent infusion as soon as
possible.
Sometimes diarrhoea can be helped by
having breaks of four to eight hours in
feeding, or changing to a fibre-containing
feed. Many medicines can cause or aggravate
diarrhoea, including H 2 blockers, proton
pump inhibitors, antibiotics, magnesiumcontaining antacids, antiarrhythmics,
antihypertensives and non-steroidal antiinflammatory drugs. Antibiotics can affect
colonic flora and reduce short-chain fatty acid
production from insoluble carbohydrates and
fibre. Some liquid medicines contain sorbitol,
which has laxative properties, while others
have a high osmolality and can cause osmotic
diarrhoea, especially with jejunal
administration. Pharmacists can advise on
alternative products and formulations if
diarrhoea persists.
A motility agent, such as metoclopramide,
may be considered for patients with slow
gastric emptying.
Choice of feed
More potassium, magnesium and
phosphate than normal is needed after
starvation to restore and maintain stores and
plasma levels, and to allow protein synthesis to
proceed optimally. More potassium is also
required in patients receiving diuretics or
insulin. Hypomagnesaemia due to diureticinduced excretion, stoma losses, fistulae or
diarrhoea can worsen hypokalaemia.
Correcting potassium, magnesium and
phosphate deficiencies while feeding can
reduce or prevent refeeding problems.
Essential vitamins, minerals and trace
elements are required for the prevention or
correction of deficiency states and
maintenance of normal metabolism and
antioxidant status. Standard enteral feeds
providing total daily energy needs contain
daily recommended micronutrient
requirements but these may not suffice if there
are increased demands due to illness, preexisting micronutrient deficits, poor
absorption or when full enteral tube feeding is
not tolerated in the initial period of feeding.
Refeeding syndrome, a set of metabolic
complications seen when feeding is started
after prolonged malnutrition due to a
depletion of certain electrolytes (especially
phosphates) and water soluble vitamins, can
be life threatening, resulting in cardiac or
respiratory failure or other problems. NICE
recommends the prescription of B vitamins,
especially thiamine, when starting feeding in
the very malnourished, along with a gentle
start to nutrition.
Enteral syringe used for bolus feeding (Baxa Ltd)
Monitoring
Enteral tube feeding is effective and safe but
carries a number of risks that close monitoring
can prevent. Metabolic complications of
enteral tube feeding, in addition to refeeding
syndrome, include hyperglycaemia, electrolyte
disturbances, clotting disturbances and
oedema due to fluid overload. (In hospital
fluid balance records and regular body weight
are useful when assessing fluid status.)
Initially, electrolytes and blood glucose need to
be checked daily, and weekly full blood counts
and liver function tests are required until the
patient is stable.
Nasogastric and nasojejunal tubes are
easily displaced so their position should be
checked before each feed (testing tube aspirate
with litmus paper). Gastrostomy and
jejunostomy sites should be checked daily,
both for tube positioning and infection. The
patency of tubes should also be checked.
Patients should also be monitored for
adverse effects. Gastrointestinal problems,
such as bloating and diarrhoea, are common
Choice of feed is influenced by
gastrointestinal absorption or motility
problems and other co-morbidities, such as
renal or liver disease.
Feeds are prescribable (on FP10, GP10
and WP10) for disease-related malnutrition,
malabsorption states and dysphagia. Allowed
feeds are listed in appendix 7 of the British
National Formulary and prescriptions should
be endorsed “ACBS” (ie, Advisory
Committee on Borderline Substances
approved for specific indications). Although
oral sip feeds (eg, Ensure Plus) do not fit into
the narrow definition of enteral feeding some
can be given through feeding tubes so will also
be considered in this section.
Enteral and sip feeds provide varying
amounts of nutrients and fluid from differing
combinations of fat, carbohydrate and protein.
The variety of feeds available include those
that are nutritionally complete when given in
the recommended amount, and which be used
as a sole source of nutrition, and those that
provide calories but lack other essential
Helen Campbell will be available to answer
questions online on the topic of this article
until 9 August 2010
Ask the
expert
www.pjonline.com
July 2010
www.pjonline.com
PJ, LandD online only July 2010_Layout 1 7/15/2010 11:46 AM Page 4
4 PJ Online
Learning & development
components of a complete diet so are
intended to be used as supplements.
Nutritionally complete feeds commonly
seen include Ensure Plus and Fortisip and
these are suitable for sip feeding or bolus
administration into the stomach via a PEG
tube but are not suitable for jejunal feeding.
Jevity and Nutrison are examples of complete
feeds used in tube feeding only.
Not all patients who are tube fed are
unable to eat. Some may be able to eat small
amounts but need enteral feeding to ensure
their full nutritional requirements are met (ie,
these people may be prescribed enteral feeds
in addition to dietary and other oral
supplements). Well known feeds that should
not be used as a sole source of nutrition and
are intended for use as supplements include
Ensure Plus Juce, Fortijuce, Scandishake and
Vitasavoury Soups. Calogen is a popular fat
emulsion that provides high levels of calories
but little else.
Most feeds contain a partially hydrolysed
starch as the carbohydrate source, whole
protein for nitrogen, and long-chain
triglycerides (LCT) to supply lipid. Energy
supply can vary from less than 0.9kcal/ml
(low) to more than 1.2kcal/ml (high). Very
calorie dense formulae have recently been
marketed, providing 2kcal/ml or above and
these benefit patients with fluid restriction,
such as in chronic kidney disease or cardiac
failure and for adults with early satiety.
Most feeds are available as fibrecontaining or fibre-free, and are generally
gluten free. Traditionally, enteral feeds were
fibre-free because fibre was thought to cause
tube obstruction, but the normal
recommended fibre intake of 15 to 30g per
day can be provided by the enteral feed. In
fact, fermentable (soluble) fibre from guar
gum, pectin and soy polysaccharides, and
non-fermentable fibre (non-soluble), such as
oat fibre, are beneficial to maintain gut
physiology, prevent diarrhoea and
PRACTICE POINTS
Reading is only one way to undertake CPD
and the regulator will expect to see various
approaches in a pharmacist’s CPD portfolio.
1 Familiarise yourself with sections 7.1 to 7.4
of appendix 7 in the British National
Formulary. Consider typical indications for
patients to be receiving enteral or oral
nutrition.
2 Discuss with a colleague what you would
consider if asked to recommend a
medicine for administration via an enteral
feeding tube.
3 Make sure you can describe the
differences between the various enteral
and oral feeds and supplements available.
Consider making this activity one of your nine
CPD entries this year.
July 2010
www.pjonline.com
constipation, and for glycaemic and lipid
control. Fermentable fibre is broken down to
short-chain fatty acids in the colon.
More recently, oligosaccharides, such as
inulin, and fructo/galacto-oligosaccharides, are
being introduced to feed formulations because
they are also metabolised by gut bacteria,
resulting in improved gastrointestinal
function.
Many feeds are described as “clinically
lactose free”, containing less than 1g lactose
per 100ml of formula. These are suitable for
patients with primary or secondary lactase
deficiency (caused by gut damage due to
inflammation, infection, short bowel or rapid
small bowel transit time) where malabsorption
of lactose would cause diarrhoea.
Soya protein formulae are available for
patients with intolerance to dairy products.
The long-chain omega-3 fatty acids DHA
(docosahexaenoic acid) and EPA
(eicosapentanoic acid) present in oily fish
have been linked with health — particularly
cardiovascular — benefits. Increasing omega-3
intake may also have a role in the prevention
of dementia. Feeds that include fish oils in
their formulation are now available. Panel 2
(p3) describes some disease specific feeds.
There is an increasing range of nutritional
products available. These impose a significant
acquisition cost implication on purchasers and
for this and clinical reasons patients should be
assessed by a dietitian or experienced health
professional before and while receiving enteral
nutrition in order that only appropriate
products and quantities are prescribed. For
patients requiring a vegan or religious diet, the
suitability of individual products should be
confirmed with manufacturers.
When patients are discharged from
hospital on continuing enteral tube feeding,
care must be taken to ensure that the
arrangements for the supply of feeds and
equipment is in place and that all carers are
fully informed. Whether the feeds are intended
for bolus or infusion administration needs to
be specified. Although enteral feeding is
usually started in secondary care, GPs can
also refer patients for placement of feeding
tubes. Patients are managed by a community
dietitians and may be followed up by hospital
nutrition teams as outpatients. Health care
professionals should also be aware of the
potential impact of tube feeding on the eating
habits of carers, who may not bother
preparing proper meals, if they are just
cooking for themselves.
Medicines
Pharmacists may be asked to advise on the
administration of medicines via feeding tubes
as well as possible interactions between drugs
and feeds.
Most medicines are not licensed for
administration through enteral tubes. In
general, medicines administered via an enteral
feed tube should be given separate from the
feed, flushing the tube with water before and
after each medicine and only used after
establishing compatibility with the feed.
The much-reduced bioavailability of
phenytoin is the best known example among
many drug-feed interactions and feed should
be stopped for two hours before phenytoin is
given. Some advice is based on
recommendations given with products
dispensed for oral use so, for example,
tetracycline should not be given with milky
feeds and if penicillin is given, feeds should be
stopped for an hour before and after dosing
(see Resources for further details).
Dispersible tablets, elixirs or suspensions
are preferable to syrups because of the effects
of high osmolality (eg, diarrhoea).
Blockage of tubes is common if adequate
flushing is not performed after each
administration of both feed and each
medicine. Crushed tablets, potassium, iron
supplements and sucralfate are particularly
likely to cause blockage problems. Unblocking
can be attempted (usually by nursing staff) by
flushing with warm water or an alkaline
solution of pancreatic enzymes, but sometimes
tubes will need to be replaced.
Summary
With an increasing awareness of the potential
morbidity, mortality, and financial burdens
associated with malnutrition, enteral and oral
sip feeds are being increasingly used based on
a strong evidence and NICE
recommendations. A general knowledge of
enteral feeding is, therefore, of value to
pharmacists.
Resources
• “The handbook of drug administration via
enteral feeding tubes” (R White et al,
Pharmaceutical Press) is a practical guide to the
safe administration of medicines via enteral
feeding tubes. It includes information on drug
therapy review, medication formulation choice
and unlicensed medication use as well as
guidance on the safe administration of specific
drugs and formulations.
References
1 Russell CA, Elia M. Nutrition screening survey in
the UK in 2008. British Association for
Parenteral and Enteral Nutrition (BAPEN), 2008.
2 Combating Malnutrition: Recommendations for
Action BAPEN 2009.
3 Nutrition support in adults. NICE Clinical
Guideline 32, 2006.
CPD articles are commissioned by The
Pharmaceutical Journal and are not peer
reviewed.
Authors
Helen Campbell, DipClinPharm,
MRPharmS, is senior pharmacist for
nutrition and surgical services, and Peter
Turner, MSc, RD, is specialist dietitian for
nutritional support at the Royal Liverpool
and Broadgreen University Hospitals NHS
Trust. John Sexton, MSc, MRPharmS, is
principal pharmacist lecturer-practitioner at
the Royal Liverpool and Broadgreen
University Hospitals NHS Trust and
Liverpool John Moores University.