1
Third stage
Medicine
Lec-3
د
.
وائل
1/1/2014
Under-nutrition and hospital nutrition
There remain regions of the world, particularly rural Africa, where under-nutrition due to
famine is endemic, the prevalence of BMI < 18.5 kg/m2 in adults is as high as 20%, and
growth retardation due to under-nutrition affects 50% of children.
under-nutrition is defined as BMI<18.5,and can be graded to 3 stages:
Mild:BMI 17-18.5
Moderate:16-17
Severe : less than 16
Causes of under-nutrition and weight loss in adults:
A) Decreased energy intake:
Famine
Persistent regurgitation or vomiting
Anorexia, including anorexia nervosa
Malabsorption (e.g. small intestinal disease)
Maldigestion (e.g. pancreatic exocrine insufficiency)
B) Increased energy expenditure:
Increased BMR (thyrotoxicosis, trauma, fever, cancer cachexia)
Excessive physical activity (e.g. marathon runners)
Energy loss (e.g. glycosuria in diabetes)
Impaired energy storage (e.g. Addison's disease, phaeochromocytoma) .
Clinical features:
weight loss
thirst, craving for food, weakness and feeling cold
nocturia, amenorrhoea or impotence
lax, pale, dry skin with loss of turgor and, occasionally, pigmented patches
cold and cyanosed extremities, pressure sores
hair thinning or loss (except in adolescents)
muscle-wasting, best demonstrated by the loss of the temporalis and periscapular
muscles and reduced mid-arm circumference
loss of subcutaneous fat, reflected in reduced skinfold thickness and mid-arm
circumference
hypothermia, bradycardia, hypotension and small heart
oedema, which may be present without hypoalbuminaemia ('famine oedema')
distended abdomen with diarrhoea
diminished tendon jerks
apathy, loss of initiative, depression, introversion, aggression if food is nearby
2
susceptibility to infections: Gastroenteritis and Gram-negative
septicaemia,Respiratory infections, especially bronchopneumonia,Certain viral
diseases, especially measles and herpes simplex,Tuberculosis,Streptococcal and
staphylococcal skin infections,Helminthic infestations .
laboratory investigations: severe cases:
plasma free fatty acids are increased and there is ketosis and a mild metabolic
acidosis.
Plasma glucose is low but albumin concentration is often maintained because the
liver still functions normally.
Insulin secretion is diminished, glucagon and cortisol tend to increase, and reverse T3
replaces normal triiodothyronine
The resting metabolic rate falls, partly because of reduced lean body mass and partly
because of hypothalamic compensation.
There may be mild anaemia, leucopenia and thrombocytopenia.
The erythrocyte sedimentation rate is normal unless there is infection.
The electrocardiogram shows sinus bradycardia and low voltage..
Management:
Whether in a famine or in wasting secondary to disease, the severity of under-
nutrition is graded according to BMI. People with mild starvation are in no danger;
those with moderate starvation need extra feeding; those who are severely
underweight need hospital care.
In severe starvation, there is atrophy of the intestinal epithelium and of the exocrine
pancreas, and the bile is dilute. When food becomes available, it should be given by
mouth in small, frequent amounts at first, using a suitable formula preparation .
Individual energy requirements can vary by 30%. During rehabilitation, more
concentrated formula can be given with additional food that is palatable and similar
to the usual staple meal.
Salt should be restricted and micronutrient supplements may be essential (e.g.
potassium, magnesium, zinc and multivitamins). Between 6.3 and 8.4 MJ/day (1500-
2000 kcal/day) will arrest progressive under-nutrition, but additional energy may be
required for regain of weight.
During refeeding, a weight gain of 5% body weight per month indicates satisfactory
progress. Other care is supportive, and includes attention to the skin, adequate
hydration, treatment of infections, and careful monitoring of body temperature since
thermoregulation may be impaired
Under-nutrition in hospital:
Under-nutrition is a common problem in the hospital setting. In the UK,
approximately one-third of patients are affected by moderate or severe under-
nutrition on admission. The elderly are particularly at risk (Box 5.34). Once in
hospital, many patients lose weight due to factors such as poor appetite, poor dental
3
health, concurrent illness and even being kept 'nil by mouth' for investigations.
Under-nutrition is poorly recognised in hospital and has serious consequences.
Nutritional support of the hospital patient:
Normal diet: As a first step, patients should be encouraged to eat a normal and
adequate diet. This is often neglected and there is evidence of substantial wastage in
hospital food. In patients at risk of under-nutrition ,quantities eaten should be
recorded on a food chart. Hospital staff must identify and overcome barriers to
adequate food intake, such as unpalatability of food, cultural and religious factors
influencing acceptability of food, difficulty with hand dexterity (arthritis, stroke),
immobility in bed, or poor oral health. Hospital catering departments have an
important role in providing acceptable and adequate meals.
Dietary supplement: If sufficient nutritional intake cannot be achieved from normal
diet alone, then dietary supplements should be used. These are drinks with high
energy and protein content, and are available in cartons as manufactured, flavoured
products or made in the hospital kitchen from milk products and egg. They should be
prescribed, and administered by nursing staff, to ensure that they are taken
regularly. Dietary supplements do not significantly affect the patient's consumption
of normal food.
Enteral tube feeding: Patients who are unable to swallow may require artificial
nutritional support: for example, after acute stroke or throat surgery or with long-
term neurological problems such as motor neuron disease and multiple sclerosis. The
enteral route should always be used if possible, since feeding via the gastrointestinal
tract preserves the integrity of the mucosal barrier. This prevents bacteraemia and, in
intensive care patients, reduces the risk of multi-organ failure .
Parenteral nutrition:
Intravenous feeding should only be used when enteral feeding Is impossible.
Parenteral feeding is expensive and carries higher risks of complications. There is little
benefit if parenteral feeding is required for less than 1 week.
There are a number of possible routes for parenteral nutrition:
Peripheral venous cannula. This can only be used for low-osmolality solutions due to
the development of thrombophlebitis, and is unsuitable for patients with high
nutritional requirements.
Peripherally inserted cannula (PIC). A 20 cm cannula is placed in a mid-arm vein.
Once again, hyperosmolar solutions cannot be used.
Peripherally inserted central catheter (PICC). A 60 cm cannula is inserted into a vein
in the antecubital fossa. The distal end lies in a central vein, allowing hyperosmolar
solutions to be used.
Central line. The subclavian route is preferred to the internal jugular vein, due to
lower infection rates. Hyperosmolar solutions can be used without difficulty. Lines
4
need to be handled with strict aseptic technique, and a single lumen tube is
preferred, to prevent infection.
If access has been gained to a central vein, nutritional support is usually given as an
'all in one' mixture. The main energy source is provided by carbohydrate, usually as
glucose. The solution also contains amino acids, lipid emulsion, electrolytes, trace
elements and vitamins. These are mixed as a large bag in a sterile environment, with
the constituents adjusted according to the results of regular blood monitoring.
Relevant tests include:
daily: urea and electrolytes, glucose
twice weekly: liver function tests, calcium, phosphate, magnesium
weekly: full blood count, zinc, triglycerides
monthly: copper, selenium, manganese