TPN may be the only feasible option for patients who do not have a functioning GI tract or who have disorders requiring complete bowel rest, such as the following:
Some stages of ulcerative colitis
Short bowel syndrome due to surgery
Nutritional content: TPN requires water (30 to 40 mL/kg/day), energy (30 to 45 kcal/kg/day, depending on energy expenditure), amino acids (1.0 to 2.0 g/kg/day, depending on the degree of catabolism), essential fatty acids, vitamins, and minerals. Children who need TPN may have different fluid requirements and need more energy (up to 120 kcal/kg/day) and amino acids (up to 2.5 or 3.5 g/kg/day).
Basic TPN solutions are prepared using sterile techniques, usually in liter batches according to standard formulas. Normally, 2 L/day of the standard solution is needed. Solutions may be modified based on laboratory results, underlying disorders, hyper metabolism, or other factors. Most calories are supplied as carbohydrate. Typically, about 4 to 5 mg/kg/min of dextrose is given. Standard solutions contain up to about 25% dextrose, but the amount and concentration depend on other factors, such as metabolic needs and the proportion of caloric needs that are supplied by lipids. Commercially available lipid emulsions are often added to supply essential fatty acids and triglycerides; 20 to 30% of total calories are usually supplied as lipids. However, withholding lipids and their calories may help obese patients mobilize endogenous fat stores, increasing insulin sensitivity. Solutions: Many solutions are commonly used. Electrolytes can be added to meet the patient's needs.
For renal insufficiency not being treated with dialysis or for liver failure: Reduced protein content and a high percentage of essential amino acids
For heart or kidney failure: Limited volume (liquid) intake
For respiratory failure: A lipid emulsion that provides most of nonprotein calories to minimize CO2 production by carbohydrate metabolism
For neonates: Lower dextrose concentrations (17 to 18%)
Beginning TPN administration: Because the central venous catheter needs to remain in place for a long time, strict sterile technique must be used during insertion and maintenance. The TPN line should not be used for any other purpose. External tubing should be changed every 24 h with the first bag of the day. Dressings should be kept sterile and are usually changed every 48 h using strict sterile techniques. If TPN is given outside the hospital, patients must be taught to recognize symptoms of infection, and qualified home nursing must be arranged. The solution is started slowly at 50% of the calculated requirements, using 5% dextrose to make up the balance of fluid requirements. Energy and nitrogen should be given simultaneously. The amount of regular insulin given (added directly to the TPN solution) depends on the plasma glucose level; if the level is normal and the final solution contains 25% dextrose, the usual starting dose is 5 to 10 units of regular insulin/L of TPN fluid.
Monitoring: Weight, CBC, electrolytes, and BUN should be monitored often (eg, daily for inpatients). Plasma glucose should be monitored every 6 h until patients and glucose levels become stable. Fluid intake and output should be monitored continuously. When patients become stable, blood tests can be done much less often. Liver function tests should be done. Plasma proteins (eg, serum albumin,), prothrombin time, plasma and urine osmolality, and Ca, Mg, and phosphate should be measured twice/wk.
■ Monitor vital signs, observing for signs of infection…