Predicting energy needs in ventilator-dependent critically ill patients: effect of adjusting weight for edema or adiposity.

Predicting energy needs in critical illness can be difficult because of uncertainties about the influence of multiple factors on energy expenditure. Understanding these components is important to avoid limiting optimal outcome by underfeeding and to avoid complications of overfeeding. Prediction strategies often use a patient's weight to estimate needs. For overweight patients, there is controversy as to whether actual or modified weight should be used in predictions. This study was designed to evaluate a proposed technique to improve the accuracy of predicting energy needs in critically ill, overweight subjects. Subjects' energy needs were predicted [with Harris-Benedict equation (HBE) and kilojoules per kilogram (KPK) strategies] by using both actual weight and an adjusted weight developed to attempt to more accurately reflect lean mass. Results were compared with measured energy expenditure determined by indirect calorimetry. Results indicated that use of actual weights in predictions for overweight subjects may lead to overfeeding. Use of adjusted weights led to more accurate energy predictions with the KPK than with the HBE strategy. Adjusted-weight strategies could explain > 45% of the variability of resting energy expenditure in subjects 130-159% of ideal body weight. Results of this study suggest that using adjusted weights with the KPK prediction strategy may be preferable for this population, particularly for patients > or = 130% of ideal body weight. This study also indicated that multiple diagnoses may not lead to increased energy requirements.

A survey of management tasks completed by clinical dietitians in the practice setting.

OBJECTIVE: To investigate clinical dietitians' involvement in completing management tasks in a practice setting. DESIGN: A random sample of 1,599 self-designated clinical dietitians was selected to receive the survey. The survey instrument consisted of 54 management tasks divided into four management categories: personnel, materials, financial, and organizations. For each task, the respondent was to indicate frequency of task completion and setting that contributed the most in providing competency for task completion. STATISTICAL ANALYSIS: A 38% response rate was achieved and 526 surveys were submitted for data analysis. Responses for number of respondents completing each task, frequency of task completion, and training setting were generated for position title, number of years as a registered dietitian, number of employees supervised, and size of hospital. chi 2 Analysis was used to determine degree of association among variables. RESULTS: Every task listed on the survey was completed by at least some of the respondents. Financial management tasks had the lowest incidence of response. Clinical dietitians were found to be assuming management responsibilities to varying degrees in the practice setting; 50% or more of the respondents performed tasks in the personnel area. The position title of the dietitian influenced which tasks were completed in the practice setting but was independent of frequency of task completion. Work experience was the setting that contributed the most to attaining skills needed for task completion. CONCLUSIONS: Management is a viable component of clinical dietitians' responsibility. Knowledge of activities and requirements of the workplace is essential if dietitians are to be competitive in the professional job market. With the current drive for cost-effective, quality patient care, clinical dietitians will be expected to have competent management skills.

Influence of age and magnesium on calcium metabolism in rats.

This study evaluates the effect of dietary magnesium concentration on calcium metabolism in rats of differing ages. Young (3 wk) and old (18 mo) Fischer 344 rats were fed the AIN-76A diet modified to contain either low (218 mg/kg) or adequate (419 mg/kg) Mg for 4 wk. Some rats subsequently underwent a metabolic balance study (12 d duration). Other rats were gavaged with approximately 220 KBq (6 microCi) of 47Ca; daily fecal and urine collections were made and periodic whole body radioactivity determined. Femurs were removed and analyzed. Calcium retention and balance were not affected by Mg in young rats. In old rats low Mg intake increased apparent Ca balance. Young rats retained about 3.25 times more of the original dose of 47Ca than did old rats. Young rats retained more 47Ca in the femur than did old rats; Mg intake had little effect. Aging accelerated Ca turnover rate, and whole body retention data suggest that adequate Mg does not significantly reduce Ca turnover.

Consequences of utilizing reduced nutrient data bases for estimating dietary adequacy.

The USDA Nutrient Data Base (NDB) used to calculate dietary intake in the Nationwide Food Consumption Survey of Individuals 1977-1978 (NFCS) was reduced to two levels. Both reduced data bases were used in analysis of 3-day dietary records collected on 7,914 individuals during the first quarter of that survey. Baseline nutrient intake values for energy and 14 nutrients for 22 sex-age groups were calculated prior to NDB reduction. After reduction, nutrient intake values were again calculated. The magnitude of variation was determined, and ANOVA was used to evaluate those variations at both substitution levels. The NDB reductions resulted in significant alterations in calculated nutrient intake and interactions between NDB type and various sex-age groups. However, the magnitude of the differences in calculated nutrient levels between the original and reduced data bases was, generally, quite small. The notable exception was in the under-1-year sex-age group. On the basis of this study, predictions of nutritional adequacy for the NFCS using the smaller data bases would show essentially the same trends as obtained from the original data base.

Effect of zinc intake on copper excretion and retention in men.

To determine the influence of zinc intake on copper excretion and retention, nine men consumed diets containing 2.6 mg of copper/day and 1.8, 4.0, 6.0, 8.0, 18.5 or 20.7 mg of zinc/day for one- or two-week periods in a 63-day study. Copper and zinc in the diet and copper in plasma were determined weekly; fecal copper was determined daily and averaged within each week. The weekly mean (+/-SEM) plasma copper concentrations (81 +/- 3.3 to 100 +/- 5.8 micrograms/dl) remained within the normal range throughout the study. Fecal copper and apparent copper retention were influenced by the level of dietary zinc and the duration it was fed. When 18.5 mg of zinc/day was fed for two consecutive weeks following a lower zinc intake, fecal copper was elevated and apparent copper retention was reduced after a one-week lag. Thus, an intake of zinc only 3.5 mg/day above the RDA for men reduced apparent retention of copper at an intake of 2.6 mg/day.

Effect of dietary chromium on glucose tolerance and serum cholesterol in guinea pigs.

The effects of feeding three levels of dietary chromium (Cr) to non-pregnant guinea pigs, guinea pigs during pregnancy and lactation and F-1 offspring guinea pigs on weight gain, glucose tolerance, glucose peak time value and serum cholesterol concentration has been investigated. Dietary levels of Cr were: Basal Diet (B) = 0.125 ppm; B supplemented with 0.5 ppm Cr (S1 Diet) and B supplemented with 50 ppm Cr (S2 Diet). All groups had similar weight gain patterns and daily feed intake levels. Parent generation guinea pigs fed the B diet consumed less than 10 mug Cr/kg body weight/day while F-U guinea pigs consumed more than this amount. Mortality rates during pregnancy were greater in guinea pigs fed the B diet than in the Cr supplemented groups suggesting a possible protective effect by Dr. Glucose tolerance, glucose peak time values and serum cholesterol appeared to be more affected by pregnancy and generation of guinea pigs than by the level of dietary Cr. Results suggest that species differences may exist between Cr requirements of guinea pigs and rodents for avoiding glucose tolerance.