Measured versus predicted oxygen consumption in children with congenital heart disease. (1/799)

OBJECTIVE: To compare measured and predicted oxygen consumption (VO2) in children with congenital heart disease. DESIGN: Retrospective study. SETTING: The cardiac catheterisation laboratory in a university hospital. PATIENTS: 125 children undergoing preoperative cardiac catheterisation. INTERVENTIONS: VO2 was measured using indirect calorimetry; the predicted values were calculated from regression equations published by Lindahl, Wessel et al, and Lundell et al. Stepwise linear regression and analysis of variance were used to evaluate the influence of age, sex, weight, height, cardiac malformation, and heart failure on the bias and precision of predicted VO2. An artificial neural network was trained and used to produce an estimate of VO2 employing the same variables. The various estimates for VO2 were evaluated by calculating their bias and precision values. RESULTS: Lindahl's equation produced the highest precision (+/- 42%) of the regression based estimates. The corresponding average bias of the predicted VO2 was 3% (range -66% to 43%). When VO2 was predicted according to regression equations by Wessel and Lundell, the bias and precision were 0% and +/- 44%, and -16% and +/- 51%, respectively. The neural network predicted VO2 from variables included in the regression equations with a bias of 6% and precision +/- 29%; addition of further variables failed to improve this estimate. CONCLUSIONS: Both regression based and artificial intelligence based techniques were inaccurate for predicting preoperative VO2 in patients with congenital heart disease. Measurement of VO2 is necessary in the preoperative evaluation of these patients.  (+info)

Comparison of indirect calorimetry, the Fick method, and prediction equations in estimating the energy requirements of critically ill patients. (2/799)

BACKGROUND: Accurate measurement of resting energy expenditure (REE) is helpful in determining the energy needs of critically ill patients requiring nutritional support. Currently, the most accurate clinical tool used to measure REE is indirect calorimetry, which is expensive, requires trained personnel, and has significant error at higher inspired oxygen concentrations. OBJECTIVE: The purpose of this study was to compare REE measured by indirect calorimetry with REE calculated by using the Fick method and prediction equations by Harris-Benedict, Ireton-Jones, Fusco, and Frankenfield. DESIGN: REEs of 36 patients [12 men and 24 women, mean age 58+/-22 y and mean Acute Physiology and Chronic Health Evaluation II score 22+/-8] in a hospital intensive care unit and receiving mechanical ventilation and total parenteral nutrition (TPN) were measured for > or = 15 min by using indirect calorimetry and compared with REEs calculated from a mean of 2 sets of hemodynamic measurements taken during the metabolic testing period with an oximetric pulmonary artery catheter. RESULTS: Mean REE by indirect calorimetry was 8381+/-1940 kJ/d and correlated poorly with the other methods tested (r = 0.057-0.154). This correlation did not improve after adjusting for changes in respiratory quotient (r2 = 0.28). CONCLUSIONS: These data do not support previous findings showing a strong correlation between REE determined by the Fick method and other prediction equations and indirect calorimetry. In critically ill patients receiving TPN, indirect calorimetry, if available, remains the most appropriate clinical tool for accurate measurement of REE.  (+info)

Physical activity assessment in American Indian schoolchildren in the Pathways study. (3/799)

The objective of the Pathways physical activity feasibility study was to develop methods for comparing type and amount of activity between intervention and control schools participating in a school-based obesity prevention program. Two methods proved feasible: 1) a specially designed 24-h physical activity recall questionnaire for assessing the frequency and type of activities and 2) use of a triaxial accelerometer for assessing amount of activity. Results from pilot studies supporting the use of these methods are described. Analyses of activity during different segments of the day showed that children were most active after school. The activities reported most frequently (e.g., basketball and mixed walking and running) were also the ones found to be most popular in the study population on the basis of formative assessment surveys. Both the physical activity recall questionnaire and the triaxial accelerometer methods will be used to assess the effects of the full-scale intervention on physical activity.  (+info)

Energy and substrate metabolism in patients with active Crohn's disease. (4/799)

The aim of the study was to evaluate the possible contribution of changes in energy metabolism and substrate oxidation rates to malnutrition in Crohn's disease and to assess the effect of enteral nutrition on these parameters. Energy metabolism was evaluated by indirect calorimetry in 32 patients with active Crohn's disease and 19 age- and sex-matched healthy individuals. Measurements were done in the postabsorptive state. Seven out of 32 patients received enteral nutrition via a nasogastric tube. In these patients, resting energy metabolism was determined at d 0 (postabsorptive), 7, 14 (during full enteral nutrition) and 15 (postabsorptive). Resting energy expenditure was not significantly different between patients and controls, whereas the respiratory quotient (RQ) was lower in patients (0.78 +/- 0.05 vs. 0.86 +/- 0.05; P < 0.05). During enteral nutrition in 7 patients with Crohn's disease, the RQ increased on d 7 compared with d 0 and remained high even after cessation of enteral nutrition (d 0, 0.78 +/- 0.03; d 7, 0.91 +/- 0.04; d 15, 0. 84 +/- 0.05; P < 0.05; d 7 and 15 vs. d 0). No effects of enteral nutrition on resting energy expenditure were found. Active Crohn's disease is associated with changes in substrate metabolism that resemble a starvation pattern. These changes appear not to be specific to Crohn's disease but to malnutrition and are readily reversed by enteral nutrition. Enteral nutrition did not affect resting energy expenditure. Wasting is a consequence of malnutrition but not of hypermetabolism in Crohn's disease.  (+info)

Acute effect of ephedrine on 24-h energy balance. (5/799)

Ephedrine is used to help achieve weight control. Data on its true efficacy and mechanisms in altering energy balance in human subjects are limited. We aimed to determine the acute effect of ephedrine on 24-h energy expenditure, mechanical work and urinary catecholamines in a double-blind, randomized, placebo-controlled, two-period crossover study. Ten healthy volunteers were given ephedrine (50 mg) or placebo thrice daily during each of two 24-h periods (ephedrine and placebo) in a whole-room indirect calorimeter, which accurately measures minute-by-minute energy expenditure and mechanical work. Measurements were taken of 24-h energy expenditure, mechanical work, urinary catecholamines and binding of (+/-)ephedrine in vitro to human beta1-, beta2- and beta3-adrenoreceptors. Twenty-four-hour energy expenditure was 3.6% greater (8965+/-1301 versus 8648+/-1347 kJ, P<0.05) with ephedrine than with placebo, but mechanical work was not different between the ephedrine and placebo periods. Noradrenaline excretion was lower with ephedrine (0.032+/-0.011 microg/mg creatinine) compared with placebo (0.044+/-0.012 microg/mg creatinine) (P<0.05). (+/-)Ephedrine is a relatively weak partial agonist of human beta1- and beta2-adrenoreceptors, and had no detectable activity at human beta3-adrenoreceptors. Ephedrine (50 mg thrice daily) modestly increases energy expenditure in normal human subjects. A lack of binding of ephedrine to beta3-adrenoreceptors and the observed decrease in urinary noradrenaline during ephedrine treatment suggest that the thermogenic effect of ephedrine results from direct beta1-/beta2-adrenoreceptor agonism. An indirect beta3-adrenergic effect through the release of noradrenaline seems unlikely as urinary noradrenaline decreased significantly with ephedrine.  (+info)

Effects of insulin and amino acids on glucose and leucine metabolism in CAPD patients. (6/799)

This study investigates the basal and insulin-stimulated glucose metabolism, substrate utilization, and protein turnover in eight patients maintained on continuous ambulatory peritoneal dialysis (CAPD) (mean age 39+/-5 yr, body mass index [BMI] 108+/-6) and 14 control subjects (mean age 33+/-4 yr, BMI 103+/-3). Euglycemic insulin clamp studies (180 min) were performed in combination with continuous indirect calorimetry and 1-14C leucine infusion (study I). Postabsorptive glucose oxidation was higher (1.75+/-0.18 versus 1.42+/-0.14 mg/kg per min) and lipid oxidation was lower (0.43+/-0.09 versus 0.61+/-0.12 mg/kg per min) in CAPD patients than in control subjects (P<0.05 versus control subjects). During the last 60 min of euglycemic hyperinsulinemia, the total rate of glucose metabolism was similar in CAPD and control subjects (6.33+/-0.51 versus 6.54+/-0.62 mg/kg per min). Both insulin-stimulated glucose oxidation (2.53+/-0.27 versus 2.64+/-0.37 mg/kg per min) and glucose storage (3.70+/-0.48 versus 3.90+/-0.58 mg/kg per min) were similar in CAPD and control subjects. Basal leucine flux (an index of endogenous proteolysis) was significantly lower in CAPD patients than in control subjects (1.21+/-0.15 versus 1.65+/-0.07 micromol/kg per min). Leucine oxidation (0.13+/-0.02 versus 0.26+/-0.02 micromol/kg per min) and nonoxidative leucine disposal (an index of protein synthesis) (1.09+/-0.16 versus 1.35+/-0.05 micromol/kg per min) were also reduced in CAPD compared with control subjects (P<0.01 versus control subjects). In response to insulin (study I), endogenous leucine flux decreased to 0.83+/-0.08 and 1.05+/-0.05 micromol/kg per min in CAPD and control subjects, respectively (all P<0.01 versus basal). Leucine oxidation declined to 0.06+/-0.01 and to 0.19+/-0.02 micromol/kg per min in CAPD and control subjects, respectively (P<0.01 versus basal). A second insulin clamp was performed in combination with an intravenous amino acid infusion (study II). During insulin plus amino acid administration, nonoxidative leucine disposal rose to 1.23+/-0.17 and 1.42+/-0.09 micromol/kg per min in CAPD and control subjects, respectively (both P<0.05 versus basal, P = NS versus control subjects), and leucine balance, an index of the net amino acid flux into protein, become positive in both groups (0.30+/-0.05 versus 0.40+/-0.07 micromol/kg per min in CAPD and control subjects, respectively) (both P<0.01 versus basal, P = NS versus control subjects). In summary, in CAPD patients: (1) basal glucose oxidation is increased; (2) basal lipid oxidation is decreased; (3) insulin-mediated glucose oxidation and storage are normal; (4) basal leucine flux is reduced; (5) the antiproteolitic action of insulin is normal; and (6) the anabolic response to insulin plus amino acid administration is normal. Uremic patients maintained on CAPD treatment show a preferential utilization of glucose as postabsorptive energy substrate; however, their anabolic response to substrate administration and the sensitivity to insulin are normal.  (+info)

Endogenous thermoregulatory rhythms of squirrel monkeys in thermoneutrality and cold. (7/799)

Whole body heat production (HP) and heat loss (HL) were examined to determine if the free-running circadian rhythm in body temperature (Tb) results from coordinated changes in HP and HL rhythms in thermoneutrality (27 degrees C) as well as mild cold (17 degrees C). Squirrel monkey metabolism (n = 6) was monitored by both indirect and direct calorimetry, with telemetered measurement of Tb and activity. Feeding was also measured. Rhythms of HP, HL, and conductance were tightly coupled with the circadian Tb rhythm at both ambient temperatures (TA). At 17 degrees C, increased HP compensated for higher HL at all phases of the Tb rhythm, resulting in only minor changes to Tb. Parallel compensatory changes of HP and HL were seen at all rhythm phases at both TA. Similar time courses of Tb, HP, and HL in their respective rhythms and the relative stability of Tb during both active and rest periods suggest action of the circadian timing system on Tb set point.  (+info)

Effect of protein intake and physical activity on 24-h pattern and rate of macronutrient utilization. (8/799)

Effects of moderate physical activity (90 min at 45-50% of maximal O2 uptake 2 times daily) and "high" (2.5 g protein. kg-1. day-1, n = 6) or "normal" protein intake (1.0 g protein. kg-1. day-1, n = 8) on the pattern and rate of 24-h macronutrient utilization in healthy adult men were compared after a diet-exercise-adjustment period of 6 days. Energy turnover (ET) was determined by indirect and direct (suit) calorimetry, and "protein oxidation" was determined by a 24-h continuous intravenous infusion of [1-13C]leucine. Subjects were in slight positive energy balance during both studies. Protein contributed to a higher (22 vs. 10%) and carbohydrate (CHO) a lower (33 vs. 58%) proportion of total 24-h ET on the high- vs. normal-protein intake. The highest contribution of fat to ET was seen postexercise during fasting (73 and 61% of ET for high and normal, respectively). With the high-protein diet the subjects were in a positive protein (P < 0.001) and CHO balance (P < 0.05) and a negative fat balance (P < 0.05). The increased ET postexercise was not explained by increased rates of urea production and/or protein synthesis.  (+info)