SPECIAL FEEDING METHODS
1. The special feeding methods depend on the type of disease, the patient's conditions and his tolerance to food. The different modes of feeding patients are 1.Enteral 2. Parenteral
By definition enteral means 'within or by the way of the gastrointestinal tract.' As for as possible, the patient should be encouraged to ingest food through the oral route. Supplements may be added whenever necessary. The foods are administered via a tube and hence enteral feeding in also called tube feeding.
Tube feeding may be advised where the patient is unable to eat but the digestive system is functioning normally. Full fluid diets or commercial formulas may be administered through this route.
The tube may be passed through the nose into the stomach (nasogastric), duodenum (nasoduodenal) or jejunum (nasojejunal).
When there is an obstruction in the oesphagus, enteral feeding is done by passing a tube surgically through an incision in the abdominal wall into the stomach (gastrostomy), duodenum (duodenostomy) or jejunum (jejunostomy).
Indications for tube feeding
1. Inability to swallow due to paralysis of muscles of swallowing (diptheria, poliomyelites)
2. Unwillingness to eat.
3. Persistent anorexia requiring forced feeding.
4. Semiconcious or unconscious patients.
5. Severe malabsorption requiring administration of unpalatable formula.
6. Short bowel syndrome.
Babies of very low birth weight.
For enteral feeding for a short period of time locally available thin bore nasogastric tubes are usually adequate. For prolonged use, specially prepared thin bore, soft, flexible tubes are desirable.
The preparations to be administered are kept in bottles marked 'For intragastric use'. They are connected to the tube and allowed to drip into the stomach by gravity. Feeding is started as a continuous drip of 50 ml per hour, increased by 20 ml every 24 hours until the required rate is achieved (usually 100 to 120 ml per hour). There is evidence that giving intermittent boluses of feeds every two hours improves metabolism, compared to feeding by continuous drip.
The types of feeds that can be administered though a tube include:
1. Blenderized food
This is prepared for patients who cannot chew and swallow due to cancer of the oral cavity, larynx or oesophagus.
Ordinary food items which cannot be swallowed are cooked well and blenderized to make them liquid for feeding through a nasogastric tube.
2. Polymeric mixtures
Polymeric mixtures contain intact protein, fat and carbohydrate of high molecular weight and are thus lower in osmolarity and require normal digestive juices.
3. Elemental diets
Elemental diets are commercially predigested mixtures of amino acids, dextrins, sugars, electrolytes, vitamins and minerals with small amounts of fat. They are free of lactose and can be easily administered.
The main indication for elemental diets is short bowel syndrome, till functional regeneration occurs in the residual bowel. These diets are used as alternatives to intravenous feeding. The disadvantages of this diet are high cost and unpleasant taste and sometimes high osmolarity. Therefore, easily digestible and more palatable preparations of casein and egg albumin are preferred.
To prevent essential fatty acid deficiency enteral feeds should provide 4% of total calories as essential fatty acids.
Commercial enteral mixtures of varying osmolarity, digestibility, energy supply, lactose content, viscosity and fat content are available Eg: Ensure, Ensure plus, osmolite, Triosorbon, Isocal.
Methods of administration
The three common methods of tube feeding administration are
1. Continuous drip
2. Intermittent drip
This is the most common form of administration. The drip rate is adjusted in increments to prevent cramping, nausea, diarrhoea or distention. Feedings are started at 30 to 50 ml/hr every 8 or 12 hrs until the final rate is attained
In this 4-6 feeds are given with regular periods of interruption example : 4 hours on and 4 hours off.
In this method large volumes are given in a short time. For example, 200 ml is administered in a minimum time of ten minutes.
The delivery of nutrients directly into the circulation through the peripheral or central vein is termed as parenteral nutrition. This can be total or supplemental.
The total sustenance of increased nutritional requirements through intravenous feeding has been termed Total Parenteral Nutrition (TPN). When parenteral nutrition provides 30-50% of the total daily nutrients it is termed partial parentral nutrition. Intravenous feeding is best used in conditions when the patient cannot eat, will not eat, should not eat, cannot eat enough or cannot be fed adequately by tube feeding.
Conditions which necessitate parenteral feeding include
2. Inflammatory bowel disease
3. Short-bowel syndrome
4. Preoperative patients
5. Gastrointestinal fistulae.
Parenteral feed solutions
The peripheral vein solution should be of less than 600 mOsm, as higher osmolarity results in thrombosis and inflammation of the vein. The parenteral feed solutions contain;
2. emulsified fat
3. crystalline amino acids
5. electrolyes - Sodium, chlorine, phosphorus, potassium, calcium and magnesium
6. trace elements - zinc, copper, chromium, manganese and iodine
Advantages of enteral feeding over intravenous feeding
1. Convenient to administer.
3. No hospitalization.
4. No sterlization of tubes or nutrient.
5. Expert supervision not necessary.
6. Easily tolerated.
7. Avoids catheter related sepsis and infections.
8. Avoids metabolic disturbances.
Intestinal mucosa regenerates more rapidly as in case of short bowel syndrome.