How nutrition intervention changes what getting sick means

Measured versus estimated energy expenditure in mechanically ventilated critically ill patients

Accurate determination of energy expenditure is essential in patients receiving nutritional support to meet metabolic needs. The purpose of this study was to assess and compare the energy expenditure as measured by indirect calorimetry (MEE) and estimated by 5 equations in the mechanically ventilated critically ill patients. Forty-six patients were divided into either enteral nutrition (EN) (n=l2), total parenteral nutrition (TPN) (n=16) or combined (EN plus TPN) (n=l8) groups. Patients' energy expenditure was measured by indirect calorimetry on two occasions. Anthropometric and biochemical measurements, energy expenditure and medical status (APACHE II score) were also assessed in the intensive care unit (ICU) of Taichung Veteran General hospital. No significant difference was found in the MEE among the 3 groups. The type of nutritional support did not affect MEE. Energy expenditure calculated by using Harris- Benedict, Kleiber and Liu equations times the estimated stress factor did not significantly different than the values of MEE in all groups. There were significant correlations (P<0.01) between MEE and patients' sex (r=-0.499), age (r=-0.402), height (r=0.533), knee height (r=0.431), current body weight (r=0.379), usual body weight (r=0.407), ideal body weight (r=0.466) and urinary urea nitrogen (r=0.383) in the pooled group. Results demonstrated that energy expenditure could be estimated in most critically ill patients by using Harris-Benedict, Kleiber and Liu equations if the estimated stress factor is in the reasonable value.

Nutritional status of mechanically ventilated critically ill patients: comparison of different types of nutritional support

Malnutrition is a common problem in hospitalized patients. Early assessment of nutritional status may help in identifying patients for whom nutritional interventions are needed. The purpose of this study was to assess and compare the nutritional status of mechanically ventilated critically ill patients who were receiving nutritional support. Forty-nine patients were divided into either enteral nutrition, total parenteral nutrition or combined (enteral plus total parenteral nutrition) groups. Anthropometric and biochemical measurements, and medical status (APACHE II score) were assessed at the 1st day and 14th day of admission in the intensive care unit (ICU) of Taichung Veteran General Hospital. The length of ventilator dependency was significantly positively correlated with calorie and carbohydrate intake in the pooled group. Patients receiving enteral and combined nutrition showed significantly lower anthropometric measurements at the 14th day after admission. Patients in all groups had abnormal mean biochemical values at the 1st day of admission. Subjects in the combined group showed a significant increase in prealbumin and the Maastricht Index levels after 14 days. Patients in all three groups were malnourished when admitted to the ICU. Patients showed a slightly improvement of nutritional status after receiving nutritional support for 14 days.

Preoperative issues in clinical nutrition

Allowing a patient's nutritional state to deteriorate through the perioperative period adversely affects measureable outcome related to nosocomial infection, multiple organ dysfunction, wound healing, and functional recovery. Careful preoperative nutritional assessment should include a determination of the level of stress, an evaluation of the status of the GI tract, and the development of specific plans for securing enteral access. Patients already demonstrating compromise of nutritional status (defined by > 10% weight loss and serum albumin level < 2.5 g/dL) should be considered for a minimum of 7 to 10 days of nutritional repletion prior to surgery. Widespread use of total parenteral nutrition in unselected patients is unwarranted, may actually worsen outcome, and should be reserved for preoperative nutritional support only in severely malnourished patients in whom the GI tract is unavailable. Compared with the parenteral route, use of perioperative enteral feeding has been shown to provide more consistent and beneficial results, and can be expected to promote specific advantages in long-term morbidity and mortality.

Indirect calorimetry: can this technology impact patient outcome?

This review of 23 papers involving indirect calorimetry published over the past 18 months shows how our understanding of the metabolic response to injury has changed, highlights the problems introduced by use of predictive equations and alterations in indirect calorimetry testing protocol, and emphasizes the need to monitor cumulative energy balance by comparing daily caloric intake to energy expenditure.

Nutritional support of the hospitalized patient

Comprehensive care of patients in hospitals includes assessment of nutritional status and provision of appropriate support. This approach is facilitated by knowledge of the essential differences in metabolism between starved and stressed states. Nutritional assessment and care of patients in a hospital are based on answers to the following questions: Who gets it? When do they get it? How much do they get? What route is used to administer it? What kind do they get? What are common complications of enteral and parenteral support? What nutritional aspects are pertinent to common diseases?

Nutrition and the immune system

Malnutrition frequently contributes to the immunocompromise seen in hospitalized patients. Nutritional support corrects malnutrition and can reverse the associated immunocompromise. Developing an understanding of nutritional needs and the role of nutrition in immune function is essential to prevention and treatment of nutrition-related immunocompromise. Current research is defining the role of specific nutrients in immune function. Recent evidence also suggests that the route (enteral versus parenteral) of providing nutritional support can affect immune competence. Intervention trials may show a role of key nutrients in not only maintaining normal immune competence, but also in modulating immunologic outcomes in critically ill patients.

Parenteral nutrition: hospital to home

Parenteral nutrition support is the provision of essential nutrients intravenously, bypassing the intestinal tract. It is used in a variety of clinical settings and medical conditions. Parenteral nutrition is a complex technology that requires the input of many professionals, including dietitians. The role of the dietitian in parenteral nutrition support involves direct patient care, consultative services, education, program development, and research. Even though this field of practice is still developing, some common practices can be described. Nutrition assessment determination of macronutrient and micronutrient requirements, and monitoring are vital aspects of the provision of parenteral nutrition support that benefit from the knowledge and experience of a dietitian. The future of parenteral nutrition includes identification of preferred fuels for specific disease states, development of new lipid emulsions, and identification of conditionally essential nutrients.

Nutrient modulation of inflammatory and immune function

The metabolic response to injury occurs after a diverse group of surgical injuries including major surgical intervention, shock, infection, and sources of inflammation such as pancreatitis. The response is mediated by the macroendocrine system, the autonomic nervous system, and the cell-cell communication system. The clinical manifestations include now well-described clinical, physiologic, and metabolic characteristics. The approach of aggressive source control, invasive circulatory resuscitation, and nutrition/metabolic support has been associated with an overall reduction in morbidity and mortality. In those patients who do not respond to this approach, the disease process progresses to multiple organ failure syndrome with its associated high mortality. Altering the route of feeding, preventing single nutrient and generalized nutrient deficiency, and reducing nosocomial infections with selective gut decontamination have not significantly altered the course or outcome of the disease process in this latter group of patients with persistent hypermetabolism. The available data support the position that this persistent hypermetabolism represents abnormal metabolic regulation resulting in persistence of the inflammatory response with associated suppression of the immune defenses. A number of research approaches are being taken to understand and modulate this abnormal state of regulation. Because of the role of specific nutrients in these regulatory processes, beyond their role in classic nutrition support, nutrients such as arginine n-3 polyunsaturated fatty acids, and RNA are being evaluated for their ability to modulate inflammation and to improve immune function. Preliminary results are encouraging.