Parenteral Nutrition

Intestinal failures in patients cause malnutrition and even in serious conditions it may cause death due to starvation. Such failures include reduced absorption or failure in digestion. The most common problem is insufficient net absorption of electrolytes and water. The outcome of this is electrolyte imbalance and dehydration. It is not possible for such patients to feed normally through the gastrointestinal tract. The only alternative method for meeting the nutritional needs of the person is by direct administration of nutrients into the bloodstream. The method involves the use of nutritional solutions tailored as per the patients’ requirements. The solution is, most of the time, administered through an indwelling catheter. This method, first reported in 1968, has various unfounded concerns pertaining its indications, safety, benefits and complications.

Parenteral nutrition also called parenteral feeding is the method of providing nutrition intravenously into the bloodstream of patients with problems of indigestion or absorption. This method bypasses the normal digestive system. Parenteral nutrient solutions are properly formulated to meet all of an individual's requirements in the form of protein, carbohydrates energy, fats, electrolytes, trace elements and water. There are standard solutions for most patients, but most of the time nutrients solutions are specially and individually prepared to meet a patient’s needs (Howard, 1995). A pharmacist or a dietitian designs the formulation balancing the parenteral nutrient solutions for the intestinal failure patients.

There are various formulas used in determining the individual requirements. For instance, Harris-Benedict or Schofield formula equations determine a person’s energy requirements (ASPEN, 2002). The standard source of carbohydrate energy is hypersmolar glucose solution. Amino acids provide for nitrogen usually administered increasingly to promote protein synthesis. Nitrogen parenteral solutions are, usually, increasingly administered in the form of amino acids. Isomolar lipid solutions consisting of triglycerides and essential fatty acids also provide 40 to 50 percent of non protein energy (ASPEN, 2002). Water and electrolyte loss through diarrhea, vomiting and fistulae, require parenteral replacement using magnesium saline solutions. Other parenteral solutions may contain Immune-nutrients and immune-modulators such as arginine, glutamine and omega-3 fatty acids for critically ill patients. When administering these solutions, one should be careful not to exceed the required amounts to avoid related metabolic complications (Cowl & Weinstock, 2000). Such problems include acidosis due to overfeeding, liver dysfunction and hyperglycemia due to excess glucose energy (Cowl & Weinstock, 2000). Pancreatitis complications may also arise in patients with hypertriglyceridemia after administering lipid emulsions.

There are various routes of administering parenteral solutions into the blood stream. The choice of the route depends on the parenteral nutrition. These venous routes include subclavian, internal jugular, and antecubital fossa for central parenteral nutrition and antecubital fossa or vein on the back of hand for peripheral parental nutrition. Subclavian silicon rubber catheters are the most commonly used method of administration in most patients (Anderson, 2003). They are advantageous in that they are convenient and comfortable with most patients (Anderson, 2003).

This method is, most of the time, indicated for persons with under-nutrition with nonfunctional or inadequately functioning intestinal tract for a prolonged period (Anderson, 2003). Such indications include persons with inadequate bowel length, failure of intestinal motility or severe mucosal inflammation. Indications also include for patients where enteral feeding was not successful or failed to meet the nutritional requirements. In addition, patients who have undergone intestinal surgery and the bowel requires a period of “bowel rest” or in persons who require some time to allow an intestinal fistula to heal (Anderson, 2003). There are persons who require parenteral nutrition due to irreversible causes of intestinal failures such as intestinal pseudo-obstruction or short bowel syndrome.

There are many concerns raised over the complications related to parenteral feeding. Most of the complications arise from the line of administration of solutions or metabolic complications. It is essential to assess and monitor the whole procedure and process to confirm the efficacy of the process and examine the development of complications. Catheter related complications are the most common. They range from complications related to central vein cannulation to mechanical problems. Some of these include Pneumothorax, thoracic duct damage, arterial puncture, nerve injury, malposition of catheter. These relate to subclavian and jugular vein cannulation. They have higher frequencies than other complications.

 Catheter-related sepsis is of serious concern since it is one of the causes of diseases and death related to parenteral nutrition. Infection occurs either at the exit or internally inside the subcutaneous tunnel. The source of infection can be the catheter or migration of bacteria from another infection to the catheter. The main organisms include Staphylococcus aureus, Staphylococcus epidermidis, Enterococci, Candida albicans and Klebsiella pneumonia (Cowl & Weinstock, 2000). The symptoms may include fevers, local pain at the point of exit, discharge, erythema among others.

Other serious complications are the Central vein thrombosis and thrombophlebitis. Central vein thrombosis has a frequency of 5 to 28 percent and, also, causes morbidity and mortality (Cowl & Weinstock, 2000). Conditions such as swellings around the neck and on arms may suggest thrombosis. It arises mostly due to risk factors such as catheter infection, malposition of the catheter tip, dehydration or hyperosmolar feeds. Thrombophlebitis is common with peripherally inserted catheters. Catheter occlusion may also occur. It arises when there is back flow of blood or nutrients components into the lumen. Resistance to flushing and failure to aspirate also constitute incomplete occlusion. Mechanical catheter fracture and distal embolization are other catheter related problems (Cowl & Weinstock, 2000).

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