Nutritional requirements, assessment

After performing a nutrition assessment and estimating nutritional requirements, determine the optimal route to provide specialized nutrition support (e.g., oral, enteral, or parenteral). If PN is deemed necessary, venous access (i.e., peripheral or central see below) for PN infusion must be obtained. Finally, formulate a PN prescription, and administer PN according to proper safety guidelines. 

Assess the patient s condition to estimate the amount of time he or she is expected to be unable to eat adequately to meet nutritional requirements. If inadequate intake has occurred or is anticipated for 7 to 14 days, start SNS. The threshold for starting SNS is lower for previously malnourished patients than for previously well-nourished patients. 

Choose an appropriate feeding formula based on patient-specific factors. This necessitates assessing the patient s nutritional requirements. Standard polymeric formulas are appropriate for the majority of patients. 

See Chap. 143, Assessment of Nutrition Status and Nutrition Requirements, authored hy Katherine Hammond Chessman and Vanessa J. Kumpf, for a more detailed discussion of this topic. 

The effects of exercise on nutritional requirements can be assessed against the likelihood of substantial changes in one or more of these functions. 

An initial nutrition assessment and determination of nutrition requirements only defines an empirical starting point for a nutrition care plan. Close monitoring is required so that timely adjustments to the nutrition care plan can be made based on patient-specific responses to ensure appropriate nutrition-related outcomes. 

A comprehensive nutrition assessment should include a nutrition-focused medical and dietary history, a physical examination including anthropometric measmements and laboratory measurements, and provides a basis for determining the patient s nutrition requirements and the optimal type and timing of nutrition intervention. 

CHAPTER 135 ASSESSMENT OE NUTRITION STATUS AND NUTRITION REQUIREMENTS 2561... 

Better markers of nutrition status and methods for determining patient-specific nutrition requirements are needed to allow further refinement of estimates of individual nutrition needs. Functional tests and simple, noninvasive tests for body composition analysis hold promise for the future. However, until better methods of assessment become available clinically and are demonstrated to be cost-effective, the currently available battery of tests will continue to be the mainstay of nutrition assessment. 

Considerable uncertainty and controversy exists concerning the folate requirement for humans. Hie review of data concerning the human folate requirement by the Food and Nutrition Board (1989) suggests that the daily maintenance requirement is 100-200 fig of avaUable folic acid equivalents. The 1989 RDAs were reduced to 200 and 180 fig for adult men and women, respectively, from the previous RDA of 400 on the basis of such evidence (Food and Nutrition Board, 1989). Similarly, the Canadian RDA for folate was set at 3 /ig/kg body wt or 210 fig for a 70-kg individual. These lower RDAs may be inadequate for certain population groups, however (Sauberlich, 1990 Bailey, 1992 McPartlin etai, 1 3). It is currently difficult or impossible to predict the quantitative effect on folate nutritional status of factors such as (a) changes in folate intake, (b) differences in folate bioavailability, (c) effects of pregnancy and lactation on folate requirements, and (d) pharmaceuticals with antifolate properties. In addition, the development of mathematical models would improve our ability to evaluate methods of nutritional status assessment for this vitamin. 

Children have a higher calcium requirement than adults, owing to demands for skeletal growth, and their minimum requirement, assessed in the same manner as that of adults, varies with age and in adolescence with sex. The Recommended Dietary Allowances of the Food Nutrition Board (1945) give the following scale for children up to and including 9 years of age,... 

In assessing nutritional requirements, a distinction needs to be made between physiological requirements and dietary requirements. The primary task is to try to estimate physiological requirements that is, the need for the substance or substances within the body for essential metabolic functions. Dietary requirements will normally be greater than this because of the need to take into account the fact that absorption is normally less than 100% efficient and there are subsequent losses in metabolic pathways. 

Generation of data on the nutrient content of agricultural products and foods forms the basis for estimating nutrient intakes of populations via dietary surveys, nutritional labelling for consumer protection, nutrition education for consumer food choice, home and institution menu planning and food purchase, and for research in nutrient requirements and metabolism, toxicant chemical composition is used to assess effects of farm management practices, crop culture, and food processing on chemical content and implications for human health. 

Proceedings of the BEM and BERM symposia have been used to assess emerging trends in the development of RMs to meet Analytical Quality Control requirements for clinical, food, nutrition, and environmental health areas. (Iyengar and Wolf 1998) ... 

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