Identifying patients at risk^[3]

• All hospital inpatients on admission and all outpatients at their first clinic appointment should be screened. Screening should be repeated weekly for inpatients and, when there is clinical concern, for outpatients.
• Nutritional support should be considered in people who are malnourished, as defined by any of the following:
  • A body mass index (BMI) of less than 18.5 kg/m².
  • Unintentional weight loss greater than 10% within the last 3-6 months.
  • A BMI of less than 20 kg/m² and unintentional weight loss greater than 5% within the last 3-6 months.
• Nutritional support should be considered in people at risk of malnutrition, defined as those who have:
  • Eaten little or nothing for more than 5 days and/or are likely to eat little or nothing for 5 days or longer.
  • A poor absorptive capacity.
  • High nutrient losses.
  • Increased nutritional needs from causes such as catabolism.

Improving nutrition

• Antiemetics for nausea.
• Sloppy or liquid meals for patients with dysphagia from oesophageal stricture.
• Swallowing disorders from neurological causes benefit from more viscous liquids.
• Adequate pain relief may improve appetite.
• Dedicating time to feeding by nurses, healthcare assistants or relatives can help with the weak and elderly.
• When these measures are inadequate, oral supplements may be added.
• If these fail, enteral or parenteral nutrition may be required, eg for patients with prolonged unconsciousness, inability to swallow or intestinal failure. These may also be needed following major gastrointestinal (GI) surgery, in aggressive chemotherapy with severe inflammation of the mouth.
• Where possible, oral or enteral nutrition should be preferred to parenteral because it is cheaper, simpler and has other benefits, eg it maintains the integrity of the gut barrier.

Specific indications for parenteral nutrition

• Complete mechanical intestinal obstruction.
• Ileus or intestinal hypomotility.
• Severe uncontrollable diarrhoea.
• Severe acute pancreatitis.
• High-output fistulae.
• Shock.

In patients who require immediate support but are expected to improve within 1-2 weeks, peripheral vein nutritional support can be given via standard intravenous (IV) lines. Nutritional support needs to include lipid, dextrose with amino acids.

Nutritional requirements

• Water:
  • For most patients, allow 1,500 ml for the first 20 kg of body weight plus 20 ml for every kg after this, and replace additional losses as they occur.
  • In an average-sized adult, approximate needs are 30-35 ml/kg or 1 ml/kcal of energy.
• Energy:
  • This can be estimated by multiplying body weight in kg by 30-35 kcal (in obese patients, use ideal body weights).
• Protein:
  • If there are adequate calories, most patients need 0.8-1.2 g of protein/kg/day.
  • In moderate-to-severe stress, up to 1.5 g/kg/day are required.
  • Use ideal weight for patients with significant obesity.
• Electrolytes and minerals:
  • There is a large number of essential electrolytes and daily requirements will need to be tailored to the individual patient.
  • There is also a need for adequate vitamins and trace minerals, usually supplied by premixed enteral solutions (lower quantities are needed in parenteral nutrition).
• Essential fatty acids:
  • 2.4% of total calories should be given as linoleic acid.
  • In parenteral nutrition, give at least 250 ml 20% intravenous fat 2-3 x weekly.

Parenteral nutritional support systems

See separate article Parenteral Feeding.

• Basic solution comprises dextrose, amino acids and water.
• Typical solution contains 25-35% dextrose and 2.75-6% amino acids, together with minerals, vitamins and trace elements and fat emulsion (20%).
• Usually given at 30 ml/hour on day one and 60 ml/hour on day two.
• Provides adequate protein but usually inadequate energy that must be supplemented with intravenous lipids, as described earlier.
• IV fat is increasingly used in patients with large energy requirements, to prevent excess administration of dextrose.

Complications of parenteral nutrition

• Malposition of central venous catheter and possible pneumothorax.
• Catheter blockage from reflux of blood into the catheter or coagulation of the feed - consider routine heparin solution. Remove the clot with gentle suction or urokinase, hydrogen chloride or alcohol for lipid blockage.
• Infections: typically skin organisms. Needs to be inserted under aseptic conditions and not used for any other purpose.
• Fluid and electrolyte abnormalities:
  • These are common, eg hyperglycaemia, especially if the rate of infusion is not properly regulated.
  • Abnormal LFTs, deficiencies of phosphate and essential fatty acids, hyperlipidaemia, hyperammonaemia, uraemia, mineral and vitamin deficiency, respiratory distress, intestinal atrophy, metabolic bone disease.

Enteral feeding

See separate article Enteral Feeding.

• Patients who are able to sit up in bed and can protect their airways, can be fed into the stomach.
• Feeding tubes can be placed directly into the GI tract, using tube enterostomies for long-term enteral nutritional support.
• Gastrostomies allow bolus feeding but jejunostomies need continuous infusion.

Enteral nutritional support systems

• A wide range of commercially prepared solutions is available.
• In most cases, isotonic solutions containing no lactose or fibre are preferred.
• They generally contain 1,000 kcal and 37-45 g of protein/litre.
• Preparations also available with elemental solutions containing hydrolysed proteins or crystalline amino acids without significant fat content for patients with malabsorption, especially pancreatic insufficiency. They are highly hypertonic and can cause severe diarrhoea.

Complications of enteral nutrition

• The most common complications are nausea or vomiting, abdominal bloating and cramps, diarrhoea and constipation.
• Unconsciousness and impaired swallowing or vomiting may cause aspiration pneumonia, also caused by reflux. This can be prevented by giving feed directly into the small intestine via a nasogastric tube placed directly into the small intestine. Feed is controlled by infusion pump to prevent flooding.
• To prevent diarrhoea, avoid contamination of feed with bacteria, control the rate of infusion, give codeine phosphate or loperamide.
• Metabolic disturbances can occur, eg rebound hypoglycaemia after sudden withdrawal, hypokalaemia, hypophosphataemia during re-feeding.
• Blocked tubes: flush with water, warm solution of sodium bicarbonate, pancreatic enzymes. Consider using fizzy cola drinks.

Monitoring body weight

• Hydration state and overall clinical status needs daily assessment, with nutrition adjusted accordingly.
• There is also the need to measure electrolytes, serum glucose, phosphorus, magnesium, calcium and creatinine and urea daily until stabilised.