Mary Hise

How Accurate Are Resting Energy Expenditure Prediction Equations in Obese Trauma and Burn Patients

BACKGROUND While the prevalence of obesity continues to increase in our society, outdated resting energy expenditure (REE) prediction equations may overpredict energy requirements in obese patients. Accurate feeding is essential since overfeeding has been demonstrated to adversely affect outcomes. OBJECTIVES The first objective was to compare REE calculated by prediction equations to the measured REE in obese trauma and burn patients. Our hypothesis was that an equation using fat-free mass would give a more accurate prediction. The second objective was to consider the effect of a commonly used injury factor on the predicted REE. METHODS A retrospective chart review was performed on 28 patients. REE was measured using indirect calorimetry and compared with the Harris-Benedict and Cunningham equations, and an equation using type II diabetes as a factor. Statistical analyses used were paired t test, +/-95% confidence interval, and the Bland-Altman method. RESULTS Measured average REE in trauma and burn patients was 21.37 +/- 5.26 and 21.81 +/- 3.35 kcal/kg/d, respectively. Harris-Benedict underpredicted REE in trauma and burn patients to the least extent, while the Cunningham equation underpredicted REE in both populations to the greatest extent. Using an injury factor of 1.2, Cunningham continued to underestimate REE in both populations, while the Harris-Benedict and Diabetic equations overpredicted REE in both populations. CONCLUSIONS The measured average REE is significantly less than current guidelines. This finding suggests that a hypocaloric regimen is worth considering for ICU patients. Also, if an injury factor of 1.2 is incorporated in certain equations, patients may be given too many calories.

Bloodstream Infections in Patients Receiving Manufactured Parenteral Nutrition With vs Without Lipids Is the Use of Lipids Really Deleterious

BACKGROUND This study compared overall bacterial and bloodstream infection rates in patients receiving premixed parenteral nutrition (PN) with vs without lipid emulsion. METHODS Data from hospitalized patients who were ≥18 years of age and receiving premixed PN between 2005 and 2007 were extracted from the Premier Perspective database. Data were categorized into 2 groups: patients who received premixed PN only and those receiving premixed PN with lipids. Multiple logistic regression was used to adjust for risk factors and potential confounders, reporting the probability of risk for an infection. RESULTS The group without lipids was observed to have lower rates of both overall bacterial infection (43.5% vs 53.5%) and bloodstream infection (14.5% vs 18.9%). However, after adjusting for baseline characteristics, there were no significant differences in overall risk of bacterial infections (51.4% vs 53.5%; odds ratio [OR] = 1.11; 95% confidence interval [CI], 0.96-1.27) or bloodstream infections (19.6% vs 19.2%; 0.97; 0.81-1.16). In a subset of patients in the intensive care unit for ≥3 days, lower overall bacterial infection rates (58.3% vs 67.3%) and bloodstream infection rates (31.0% vs 37.0%) were observed in the group without lipids. After adjustment, there were no significant differences in risk of overall bacterial infection (OR = 0.95; 95% CI, 0.75-1.22) or bloodstream infection (0.92; 0.71-1.19) between the 2 groups. CONCLUSIONS When administered with premixed PN, lipid emulsion was not significantly associated with an increase in the risk of infectious morbidity when compared to omitting lipids from therapy.

Number of days, number of subjects, and sources of variation in longitudinal intervention or crossover feeding trials with multiple days of measurement

Dietary studies are often conducted as longitudinal intervention or crossover trials using multiple days of measurement on each subject during each of several measurement periods, and determining the required numbers of days and subjects is important in designing these studies. Linear mixed statistical models were used to derive equations for precision, statistical power and sample size (number of days and number of subjects) and to obtain estimates of between-subject, period-to-period, and day-to-day variation needed to apply the equations. Two cohorts of an on-going exercise intervention study, and a crossover study of Olestra, each with 14 d of measurement/subject per period, were used to obtain estimates of variability for energy and macronutrient intake. Numerical examples illustrate how the equations for calculating the number of days or number of subjects are applied in typical situations, and sample SAS code is given. It was found that between-subject, period-to-period, and day-to-day variation all contributed significantly to the variation in energy and macronutrient intake. The ratio of period-to-period and day-to-day standard deviations controls the trade-off between the number of days and the number of subjects, and this remained relatively stable across studies and energy and macronutrient intake variables. The greatest gains in precision were seen over the first few measurement days. Greater precision and fewer required days were noted in the study (Olestra) that exerted greater control over the subjects and diets during the feeding protocol.

Systemic Inflammatory Mediators and Bone Homeostasis in Intestinal Failure

BACKGROUND A proinflammatory state has been described in patients with intestinal failure. The prevalence of metabolic bone disease in this group is considerable. It is not known whether this proinflammatory state is related to bone parameters, though bone disease is recognized as a proinflammatory process in postmenopausal women. The purpose of this study was to examine whether inflammation was related to bone disease. METHODS Eight patients with parenteral nutrition (PN)-dependent intestinal failure but no recent infections or immunosuppressive medications had serum assayed for interleukin-6 (IL-6), tumor necrosis factor (TNF)-alpha, and its receptors (TNFR-I and TNFR-II), C-reactive protein, and whole blood for lymphocyte proliferation. Routine clinical laboratory measures of vitamin D, parathyroid hormone, serum calcium, and phosphorus within 3 months of the inflammatory measures were compared by Pearsons correlation to the inflammatory measures. RESULTS Mean values for calcium, phosphorus, and albumin were normal, but 25-hydroxy vitamin D was reduced and parathyroid hormone and alkaline phosphatase elevated. Serum total calcium was negatively related to TNFR-II, TNF-alpha and positively to T-helper cells. Longer PN dependence was associated with inflammation and negatively with T-helper cells. CONCLUSIONS These preliminary findings are hypothesis generating only but support an association of low calcium and longer duration of PN with inflammation in patients with intestinal failure. Whether the inflammation results from vitamin D deficiency or the vitamin D deficiency develops secondary to excessive use of activated vitamin D to modulate inflammation from some other cause, such as a component of PN or repeated infectious challenge, requires further study.

Inflammatory Mediators and Home Parenteral Nutrition

Individuals who have sustained intestinal failure due to trauma or disease are able to survive through the use of parenteral nutrition (PN). Although home PN (HPN) is a lifesaving therapy, patients may, over the long term, be at risk for liver, bone, and immune dysfunction. A limited number of human studies and a large number of animal studies suggest that there may be a chronic inflammatory condition and additionally a potentially lower T-lymphocyte immune function associated with PN administration. This article will primarily focus on a review of the limited clinical literature that examines the effect of long-term PN on the occurrence of inflammatory mediators in HPN patients, and will discuss the factors that are currently hypothesized to contribute to the potential inflammatory sequelae.