Patients admitted to critical care units have life-threatening illnesses and injuries. According to the 2009 journal article in "RN," acute illness further exacerbates patients' poor nutritional status by increasing their metabolic rate and impairing the allocation of nutritional substrates. Underfeeding these patients can result in a loss of lean body mass and death.
Considerations
The journal article in "RN" indicates that historically the intensive care unit population has been routinely malnourished. One explanation is that nutritional issues are often not initially explored because of the more obvious illness or injuries. The immediate complications, such as low blood pressure, chest pain, shortness of breath or unresponsiveness, require prompt attention. The effects of malnutrition may not be seen clinically for several days.
Complications
Malnutrition in the critically ill increases the risk of infection and causes muscular fatigue. If a patient is on a breathing machine, it may be harder to wean him off the machine due to reduced muscle endurance and weakness. As noted in "RN," one nutrient, protein, is especially vital in critical illness. Without adequate protein intake, the pressure gradient between blood vessels and tissues is disrupted and fluid will leak into the tissues, causing edema. Edema can further increase already existing complications, such as high blood pressure and fluid in the lungs. Decreased protein intake depletes the body's nitrogen reserve, which will result in weight loss. Other nutrients such as magnesium and phosphorus are important for wound healing.
When to Feed
According to "Nutrition and Diet Therapy," when to start nutritional feedings of the critical patient is under debate. Some physicians will not allow anything by mouth for the first 24 to 72 hours in the critical care unit. If the patient is not able to eat, tube feedings or intravenous feedings may be started within the first 24 hours of admission. Tube feedings can be used if peristalsis, the wavelike motion that propels food through the gastrointestinal tract, is present. If the gastrointestinal tract is not working, feeding through an intravenous, called total parental nutrition may be necessary.
TEN or TPN
Total enteral nutrition, or TEN, can be used when the patient has a functioning gastrointestinal tract but cannot eat enough to maintain nutrition. A tube can be placed through the nose into the stomach to use for feedings. TEN allows the gastrointestinal tract to function more normally. Total parental nutrition, or TPN, is a feeding given directly into the blood through a intravenous catheter. The difference between the two feedings is the degree of invasiveness, which is greater with TPN. TPN has a higher risk of infection associated with the intravenous site. Both TPN and TEN feedings contain nutrients such as salt and glucose, amino acids, vitamins and lipids necessary for to meet nutritional needs.
References
- "RN"; Nutrition in the ICU; Marian Racco, January 2009
- "Nutrition and Diet Therapy"; Carroll Lutz, Karen Przytulski; 2011
- "Nursing 2006"; Supporting Nutrition with TEN or TPN; Taiga Sudakin; 2006
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