Parenteral Nutrition Made Easy

DR Jon L. SHAFFER

Powerpoint File

Up to one third of hospital patients are affected by moderate or severe malnutrition1. Malnutrition Impairs immunity, organ and Muscle function; it results in weak muscles that fatigue more readily, including muscles of respiration and locomotion. Malnourished patients are withdrawn and apathetic and are less able to co-operate in their management. The restoration of body tissues occurs much more slowly than weight loss, especially in ill or septic patients. Studies have demonstrated increased morbidity and mortality in malnourished patients, and malnutrition is associated with prolonged hospital stay4. Conversely nutritional support under these circumstances has resulted in reduced morbidity, mortality and hospital stay5.

Parental nutrition will be needed when intestinal function is inadequate or the intestine is not available. Patients should not be allowed to starve for more than 7 days, and treatment may be started earlier in the malnourished or stressed patient. When peripheral veins are adequate and

The need for treatment is unlikely to exceed two weeks most nutritional needs can be met using lipid-containing nutrient mixes infused into peripheral veins through small venflons or ultra-fine bore catheters. Prolonged parenteral nutrition will need to be given by a central venous catheter.

A cuffed catheter may be preferred for longer periods of treatment in the mobile patient and when home treatment is envisaged. For HPN the possible use of a subcutaneous port should be discussed with the patient. All parenteral nutrition solutions must be administered through volumetric pumps. Central parenteral nutrition is not commenced until the satisfactory position of the catheter tip has been confirmed radiologically.

Each hospital should have guidelines for artificial nutritional support, for enteral and parenteral feeding in hospital and at home. These protocols should address patient selection, management of treatment, type and amount of nutrients to be infused, and the monitoring of treatment. Care of

infusion catheters is particularly important, to minimise the risk of serious complications such as catheter sepsis and venous thrombosis12. Protocols should also exist for the management of these complications.

Patients should be monitored by clinical, nutritional and laboratory indices according to protocols developed in each hospital. Patients who are receiving parenteral feeding need the most intensive monitoring. This will include measurement of weight, temperature and fluid balance, and biochemical monitoring of glucose, electrolytes and liver function tests. Venous catheters must be inspected daily with reference to the exit site and veins. In the longer term nutritional monitoring by anthropometric measurements is traditionally performed, but this is not likely to provide

information of short term value. Very malnourished patients require intensive monitoring for features of the re-feeding syndrome13; the rapid cellular uptake of phosphate, magnesium, potassium, and other elements, which may accompany a switch of energy source from endogenous lipid to exogenous carbohydrate, can lead to a rapid decline in serum concentrations with important metabolic consequences. Trace element and vitamin status should be measured both in these patients as well as in patients who require prolonged period of nutritional support.

The literature clearly demonstrates that artificial nutritional support is most effective, cost effective and safer, when it is supervised by multidisciplinary nutrition support teams with appropriate management protocols. In the absence of such an approach parenteral nutrition in particular is accompanied by an unacceptable incidence of dangerous and expensive complications. The function and composition of such teams may differ according to local needs.

The group usually includes a nurse, dietician, pharmacist, biochemist, and clinician. Central parenteral nutrition should be restricted to units in which the staff has

experience of this type of treatment. Artificial nutrition support at home should be supervised by a hospital with a major interest and this would usually include a NST. Patients who need home parenteral nutrition should be referred to tertiary centres. All hospitals undertaking artificial nutrition support require adequate laboratory facilities and access to supraregional centres for micronutrient assays.

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