You can give liquids and blended food through a naso-gastric tube.
Volume: The total volume should usually be about 2.5 liters a day, if the patient is not getting significant intravenous fluids.
Total protein requirements: about 50 grams a day. The requirements depend on the patients’ weight. Children need about 1 gram/kg/day; adults need 0.5 to 0.75 g/kg/day. However, patients who have fever, some infection, or also have repair needs from tissue damage e.g. after trauma: these need closer to 2 g/kg/day.
Total calories: Calculate the total protein needs, then multiply it by 25. Thus, if a patient needs 50 grams proteins/day, give 1250 calories, in non-diabetics. In diabetics, give the correct amount as calculated, do not give less, but control the blood sugar with insulin. If you give fewer calories than calculated, the proteins you give will not be utilized correctly. Carbohydrates, such as sugar, provide 4 Calories/gram. Thus 5 grams of sugar will provide 20 Calories. Fats provide 9-calories/ gram. Thus a gram of butter will provide 9 calories. Remember give most calories as carbohydrate. You should try to give no more than 30% of total calories as fat; otherwise there are metabolic problems. Also, fats are more expensive. The only use of fat is to provide some vitamins, so I would restrict the fat to not more than a spoon or two of butter or oil. Two egg yellows will do the trick.
How to give proteins: Milk is 3% protein, thus 100 ml of milk will give the patient only 3 g. The protein quality of milk is good. If you give only 2500 ml of milk through the tube, this will provide 75 g of excellent quality protein, usually enough for the patient. Usually you can blend some eggs with the milk or with water, and give them. An egg adds about 6 g of protein. You do not need to boil the eggs, unless worried about bird flu or salmonella, usually not great concerns. There are soya preparations in the market. Add a few spoons of soya: excellent quality protein. Other protein containing compounds are: meat 50% protein by weight, soya 40%, cottage cheese 40%, beans 30%, dal, etc pulses 20% (dry weight, remember), cereals 10%. Obviously, this is a rough guide.
How to give calories:Just add sugar as required to make up the caloric needs. The milk and eggs contain some calories: you can find the exact amount in the net. In addition, if your patient is short on calories, add sugar. Also, add some vitamin tablets. If not giving meat, you may be short on iron: add iron tablets.
Finally, remember, that feeds prepared and kept outside may spoil. Give 200-300 ml at a time through a gastrostomy; 100-150 ml at a time through a nasojejunal tube. A gastrostomy means you will have to give feeds 10-12 times a day, nasojejunal tube feeding requires nearly hourly feeds.