机械通气患者静息能量消耗测定

目的探讨机械通气治疗患者能量消耗与疾病严重程度的相关性,比较间接能量消耗测定仪测定的能量消耗与Harris—Benedict公式推导的能量消耗差异。方法以24例采用机械通气治疗的普外科重症监护病房患者为研究对象,收集采用机械通气72h时的相关数据计算急性生理与既往健康状况评分Ⅱ（APACHEⅡ）和MarshaⅡ评分。机械通气72h时,采用MedGraphicsCCM／DSystem能量测定系统测定静息能耗值（MREE）;采用Harris—Benedict公式计算基础能耗值,再乘以相应应激系数得出预测静息能耗值（PREE）。结果机械通气72h时,所有患者的平均APACHEⅡ评分和MarshaⅡ评分分别为（14±5）和（6±3）分,MREE和PREE分别为（6793．64±1197．15）和（8041．02±1971．54）kJ／d。MREE与PREE间无相关性（r^2=0．28,P=0．07）,差异有统计学意义（t=7．62,P=0．04）。MREE与APACHEⅡ评分（r^2=0．14,P=0．08）和MarshaⅡ评分（r^2=0．08,P=0．63）间、PREE与APACHEⅡ评分（r^2=0．05,P=0．65）和MarshaⅡ评分（r^2=0．03,P=0．87）间均无显著相关性。结论机械通气患者能量消耗与疾病严重程度无相关性。采用校正Harris—Benedict公式推导的PREE过高估计了机械通气患者的能耗水平。     

Energy expenditure and substrate utilization in mechanically ventilated children.

The objective of the study was to determine the value of indirect calorimetry and nitrogen balance (N balance) in order to evaluate the current feeding protocols of mechanically ventilated children. The study was designed as a cross-sectional prospective study. In 36 mechanically ventilated children energy expenditure was measured by indirect calorimetry, and total urinary nitrogen excretion (TUN) was determined. Substrate utilization and respiratory quotient (RQ) were calculated from the measured values of oxygen consumption (VO2), carbon dioxide production (VCO2), and TUN. The RQ was compared with the RQ of the macronutrients administered (RQmacr) according to the modified criteria of Lusk. In results, the total measured energy expenditure (TMEE) showed a wide variation (range 155-272 kJ.kg-1.d-1). The N balance was positive in 20 and negative in 16 patients. The ratio of caloric intake/TMEE was significantly higher in patients with a positive N balance (1.50 +/- 0.06) as compared with those with a negative N balance (0.8 +/- 0.1, P < 0.001). There was a significant relationship between the difference of RQ-RQmacr versus the ratio caloric intake/TMEE (r = 0.72, P < 0.001). Carbohydrate and fat utilization were not significantly different in patients with a positive or negative N balance. Protein utilization was significantly higher in those patients with a negative N balance. We concluded that measurement of TMEE with indirect calorimetry results in accurate determination of energy needs in critically ill mechanically ventilated children. Feeding according to or in excess of the TMEE is correlated with a positive N balance. A combination of the RQ and the RQmacr can be helpful in differentiating under- or overfeeding.     

Assessment of resting energy expenditure in mechanically ventilated patients

BACKGROUND: Usual equations for predicting resting energy expenditure (REE) are not appropriate for critically ill patients, and indirect calorimetry criteria render its routine use difficult. OBJECTIVE: Variables that might influence the REE of mechanically ventilated patients were evaluated to establish a predictive relation between these variables and REE. DESIGN: The REE of 70 metabolically stable, mechanically ventilated patients was prospectively measured by indirect calorimetry and calculated with the use of standard predictive models (Harris and Benedict's equations corrected for hypermetabolism factors). Patient data that might influence REE were assessed, and multivariate analysis was conducted to determine the relations between measured REE and these data. Measured and calculated REE were compared by using the Bland-Altman method. RESULTS: Multivariate analysis retained 4 independent variables defining REE: body weight (r(2) = 0.14, P < 0.0001), height (r(2) = 0.11, P = 0.0002), minute ventilation (r(2) = 0.04, P = 0.01), and body temperature (r(2) = 0.07, P = 0.002): REE (kcal/d) = 8 x body weight + 14 x height + 32 x minute ventilation + 94 x body temperature - 4834. REE calculated with this equation was well correlated with measured REE (r(2) = 0.61, P < 0.0001). Bland-Altman plots showed a mean bias approaching zero, and the limits of agreement between measured and predicted REE were clinically acceptable. CONCLUSION: Our results suggest that REE estimated on the basis of body weight, height, minute ventilation, and body temperature is clinically more relevant than are the usual predictive equations for metabolically stable, mechanically ventilated patients.     

Comparison between measured and predicted resting energy expenditure in mechanically ventilated patients with COPD

The aim of this study was to compare resting energy expenditure (REE) obtained by indirect calorimetry (IC) and Harris-Benedict (H-B) equations, and to examine whether hypocaloric nutrition support could improve protein nutritional status in mechanically ventilated patients with chronic obstructive pulmonary disease (COPD). Thirtythree COPD patients (20 males, 13 females) were recruited and REE was measured by IC. Measured REE (REEm) was compared to predictive REE by H-B equations (REEH-B) and its corrected values. Correlation between REEm and APACHE II score was also analyzed. Patients were randomly divided into hypocaloric energy group (50%-90% of REEm, En-low) and general energy group (90%-130% of REEm, En-gen) for nutrition support. The differences of albumin, prealbumin, transferrin, hemoglobin, and lymphocyte count before and after 7 days nutrition support were observed. Results show that REEH-B and REEH-B×1.2 were significantly lower than REEm (p<0.01). REEm positively correlated with APACHE II score (p<0.05 or p<0.01). After nutrition support, hemoglobin decreased significantly in En-gen group (p<0.05); lymphocyte count in both groups, and transferrin and prealbumin in the En-low group increased significantly (p<0.05 or p<0.01). Our data suggest that 1) these patients' REE were increased; 2) since IC is the best method to determine REE, in the absence of IC, H-B equations (with standard body weight) can be used to calculate REE, but the value should be adjusted by correction coefficients derived from APACHE II; 3) low energy nutrition support during mechanical ventilation in COPD patients might have better effects on improving protein nutritional status than high energy support.     

Clinical implications of continuous measurement of energy expenditure in mechanically ventilated patients

Energy expenditure was monitored in 20 critically-ill mechanically ventilated patients using the Siemens-Elema Oxygen Consumption Calculator (OCC 980). Energy expenditure was measured continuously over the 24-h period in all patients (altogether, over 2500 patient hours; range 48-288 h). A predicted energy expenditure was calculated for each patient from standard tables for basal metabolic rates modified according to previously published reports on the influence of trauma, infection and elevated body temperature. For all patients combined, the agreement between the predicted and the measured energy expenditure was good. However, in individual patients the measured energy expenditure varied between 48 and 148% of the predicted value. The measured energy expenditure in surviving traumatized and/or septic patients correlated well (95-100%) with the predicted value at the time when weaning off the ventilator could be initiated. On the first day of measurements, the energy expenditure (in % of the predicted value) in the six patients who later died was significantly lower than in surviving patients (84 +/- 6 vs 107 +/- 2%; p < 0.01). Over a 24-h period, energy expenditure, defined as the value noted during a stable 30-40-min period of measurement, varied between 12 and 50% in the individual patients. This study shows that energy expenditure cannot be accurately predicted in the individual patient, that an energy expenditure below predicted values appears to be indicative of a poor prognosis and that short periods of energy expenditure monitoring may fail to reflect 24-h conditions.     

Energy expenditure measurements in ventilated critically ill children: within- and between-day variability.

BACKGROUND: Energy expenditure measurement (EEM) by indirect calorimetry is used as a research and clinical tool in pediatric intensive care units. The aims of the study were to determine if a 30-minute EEM is representative of a 24-hour EEM (within-day variation); to determine if there is any diurnal variation during the 24-hour period of EEM; and to determine if there is a clinically significant between day variation of EEMs. METHODS: To determine within-day variation, energy expenditure was measured for a period of 24 hours for each subject (n = 11). The 24-hour period was then divided into 30-minute periods. The 30-minute means were compared with the 24-hour means. To determine between-day variation, EEMs were made daily for 30 minutes. RESULTS: In the within-day study, the overall mean percent coefficient of variation of the 30-minute measurements was 7.2% +/- 4.5%. There was no significant difference between the 30-minute means and the 24-hour means for each patient (p < .691). In 8 subjects the 30-minute means did not differ from the 24-hour mean by more than 20%. No diurnal variation was observed. The mean percent variation of between day EEM was 21% +/- 16%; the range was 1% to 69%. CONCLUSION: In critically ill ventilated children, clinically relevant within-day variations in EEM are uncommon and a single 30-minute EEM gives an acceptable guide to the level of nutrition support required. Between-day variations can, however, be large and daily EEMs are required.     

Use of infrared thermographic calorimetry to determine energy expenditure in preterm infants

BACKGROUND: Measurement of infant energy expenditure in the clinical setting is difficult and is rarely done. Both indirect and direct calorimetry require long measurement periods and frequent calibration. OBJECTIVE: The objective of this study was to validate in infants a newly developed method of determining energy expenditure, infrared thermographic calorimetry (ITC), against an established method, respiratory indirect calorimetry (IC). ITC measures mean infant body surface temperature. ITC was used in conjunction with heat loss theory to calculate radiant, convective, evaporative, and conductive heat losses and thereby determine total energy expenditure. DESIGN: Ten healthy preterm infants were studied by obtaining concurrent ITC and IC measurements over a 3.5-5.5-h study period. Continuous IC measurements were compared with ITC measurements taken every 10 min during study periods. IC values were summed over 10-min intervals covering the 5 min before and 5 min after each ITC measurement, to allow comparisons between the 2 methods. RESULTS: Comparison of paired ITC and IC mean measurements for all 10 infants over the entire study period showed no significant difference between the 2 methods. However, individual paired IC and ITC values were significantly different for 7 of 10 infants. The overall mean difference between the 2 methods was 1.3%. CONCLUSIONS: ITC is an accurate, noninvasive method for measurement of heat loss and energy expenditure in healthy preterm infants, and therefore it may be a useful clinical and research tool.     

Repeatability of 24-h energy expenditure measurements in humans by indirect calorimetry

To estimate sources and extent of variation in energy expenditure (EE), as measured by indirect calorimetry in a room-sized human calorimeter, a number of 24-h measurements were compiled. Measured oxygen consumption and carbon dioxide production from alcohol combustion experiments averaged 101.5% of the theoretical value with a coefficient of variation (CV) of 1.4%. Experiment 1 consisted of four men who had the following averages: age, 41 y; height, 179 cm; weight, 84.6 kg; and fat, 23.5%. Five measurements, separated by 1 d, were made on each subject. Daily and basal EE averaged 2852 and 1691 kcal/d, respectively, with a within-subject CV of 2.7% and 2.4%, respectively. Experiment 2 consisted of five men who had the following averages: age, 48 y; height, 181.6 cm; weight, 87 kg; and fat, 23%. Five measurements made on each subject were separated by 1-3 wk. Daily and basal EE averaged 2619 and 1837 kcal/d, respectively, with a within-subject CV of 4.6% and 2.9%, respectively.     

Indirect calorimetry: comparison of hood and mask systems for measuring resting energy expenditure in healthy volunteers

Controversy exists as to the validity and reliability of hood and mask systems in measuring indirect calorimetry. The purpose of this study was to evaluate the accuracy and reproducibility of repeat measurements of resting energy expenditure (REE) in volunteers. Paired REE measurements were performed in 23 subjects after an overnight fast using hood and mask systems. Lean body mass was calculated from four skinfold measurements and body weight determinations. Data were normalized to body weight and lean body mass and were calculated as percent predicted REE in paired tests taken within 5 minutes on the same subject. No significant difference in mean REE was noted between hood and mask systems. Linear regression analysis showed a strong positive correlation (r = 0.91, p less than 0.001) between hood and mask measurements of REE.     

Indirect calorimetry protocol development for measuring resting metabolic rate as a component of total energy expenditure in free-living postmenopausal women

An objective measure of energy intake is needed in epidemiologic studies to evaluate random and systematic error associated with dietary self-report tools. Total energy expenditure in weight-stable humans is accepted as a measure of energy intake, but doubly labeled water remains cost prohibitive for large studies. Our purpose was to develop a practical indirect calorimetry (IC) protocol for estimating resting metabolic rate (RMR) in free-living, postmenopausal women. We conducted duplicate IC measures 1 wk apart using a canopy system on 102 women ages 50-79 y from the Seattle area. We compared RMR for 0-5, 5-10, 5-15, 5-20, 5-25, 5-30, and 0- to 30-min IC segments and segments meeting stability criteria. The mean RMR for the first 5 min was significantly higher than other time segments (P = 0.001). Correlation coefficients between duplicate measures were high (r = 0.90). Use of defined stability criteria produced RMR measures that were 10-30 kcal (42-126 kJ) higher than the 5- to 10-min RMR measures and 40-60% of subjects did not achieve these stability criteria. For protocols including IC to assess RMR as a component of total energy expenditure in free-living, postmenopausal women, a single 10-min canopy study, excluding the first 5 min of data, produces reliable results with minimal subject burden.     

Resting energy expenditure in children and adolescents: agreement between calorimetry and prediction equations

BACKGROUND AND AIMS: To assess the degree of agreement between indirect calorimetry and five equations commonly used to predict resting energy expenditure (REE) in obese and non-obese children and adolescents. METHODS: In 116 children and adolescents (57 obese and 59 non-obese) aged between 7.8 and 16.6 years, REE was measured (MREE) by open-circuit indirect calorimetry under standardized conditions. REE was predicted (PREE) in all subjects with equations from the Food and Agriculture/World Health Organization/United Nations University (FAO/WHO/UNU), Maffeis et al., Harris and Benedict, and two from Schofield: one using weight (W) and one using height and weight (H-W). Agreement between indirect calorimetry and equations was assessed following the Bland-Altman method. RESULTS: In the entire cohort group, only data from FAO/WHO/UNU, Schofield-W and Schofield-HW equations showed non-statistic differences against calorimetry results. When agreement between equations and calorimetry was tested, Schofield-HW equation showed the lowest mean MREE-PREE difference: 3.7 kcal/d (limits of agreement -293 and 300 kcal/d; 95% confidence interval for the bias -24.0 to 31.5 kcal/d) and the best agreement. Group by group, equations which obtained the best agreement were: FAO/WHO/UNU in girls, Schofield-HW in boys, Schofield-HW in obese, and Schofield-W in non-obese. CONCLUSIONS: Until more accurate prediction equations are developed, we recommend Schofield-HW equations for REE studies with a mixed population of obese and non-obese children and adolescents; however, FAO/WHO/UNU equation may also be useful in girls and Schofield-W equation in non-obese children.     

Twenty-four-hour analysis of elevated energy expenditure after physical activity in a metabolic chamber: models of daily total energy expenditure

BACKGROUND: The Institute of Medicine proposed that 15% of energy expenditure (EE) as excess post-exercise oxygen consumption should be added to additional physical activity energy expenditure (DeltaPAEE) to estimate total EE. However, the magnitude of elevated post-physical activity energy expenditure (EPEE) under normal daily living conditions has not been examined. OBJECTIVE: We examined the effects of EPEE on 24-h EE by modeling standard living conditions in a metabolic chamber. DESIGN: Eleven Japanese men completed three 24-h metabolic chamber measurements: a control day (C-day), a day with high-frequency moderate-intensity physical activity (M-day), and a day with high-frequency vigorous-intensity physical activity (V-day). RESULTS: Mean (+/- SD) 24-h EE for the C-day, the M-day, and the V-day was 2228 +/- 143 kcal, 2816 +/- 197 kcal, and 2813 +/- 163 kcal, respectively. No significant difference was observed in 24-h EE between an M-day and a V-day. Mean EPEEs on the M-day and the V-day did not significantly contribute to increasing 24-h EE. Relative EPEEs to DeltaPAEEs were 6.2 +/- 13.9% (M-day) and 5.1 +/- 9.2% (V-day). However, EPEE/24-h EE was negatively correlated with maximal oxygen uptake on the V-day (r = -0.68, P = 0.02), although no significant correlation between these variables was observed on the M-day (r = -0.41, P = 0.21). CONCLUSIONS: These results suggest that EPEE has a small effect on 24-h EE in the course of normal daily activities, findings that do not support the proposition by the Institute of Medicine for estimating TEE. However, persons with low physical fitness levels could enhance EE as EPEE by increasing vigorous-intensity daily physical activity.     

Comparison of total energy expenditure and energy intake in children aged 6-9 y.

BACKGROUND: The accurate measurement of food intake in children is important for assessing nutritional status. OBJECTIVE: We sought to both compare measurements of energy intake (EI) from diet records and of total energy expenditure (TEE) by the doubly labeled water (DLW) method and to investigate misreporting of EI. DESIGN: Forty-seven children (22 boys and 25 girls) aged 7.4 +/- 0.8 y ( +/- SD) were recruited from 25 schools in western Sydney. TEE was measured by DLW over 10 d and EI by use of 3-d food records. Misreporting was defined as [(EI - TEE)/TEE] x 100%. RESULTS: Girls had a higher (P = 0.02) percentage of body fat (28.2 +/- 7.0%) than did boys (22.9 +/- 8.0%); otherwise there were no differences among sex. Although mean (+/-SD) values for EI (7514 +/- 1260 kJ/d) and TEE (7396 +/- 1281 kJ/d) were not significantly different, there was no significant correlation between EI and TEE. EI and TEE were 9% and 11% lower, respectively, than current World Health Organization recommendations for EI. The relative bias (mean difference, EI - TEE) was low at 118 kJ/d, but the limits of agreement (bias +/- 2 SD of the difference) were wide at 118 +/- 3345 kJ/d. Although the mean percentage of misreporting was low (4 +/- 23%), the high SD indicates large intraindividual differences between EI and TEE. The most significant predictor of misreporting was dietary fat intake (r(2) = 0.45, P < 0.0001). Misreporting was not associated with sex or body composition. CONCLUSIONS: In this age group, reported EI is not representative of TEE at the individual level. However, at the population level, 3-d food records may be used for surveys of EI by 6-9-y-old children.     

Measurements of daily energy intake and total energy expenditure in people with dementia in care homes: The use of wearable technology

Objective

To estimate daily total energy expenditure (TEE) using a physical activity monitor, combined with dietary assessment of energy intake to assess the relationship between daily energy expenditure and patterns of activity with energy intake in people with dementia living in care homes.

Design and setting

A cross-sectional study in care homes in the UK.

Participants

Twenty residents with confirmed dementia diagnosis were recruited from two care homes that specialised in dementia care.

Measurements

A physical activity monitor (Sensewear? Armband, Body Media, Pittsburgh, PA) was employed to objectively determine total energy expenditure, sleep duration and physical activity. The armband was placed around the left upper triceps for up to 7 days. Energy intake was determined by weighing all food and drink items over 4 days (3 weekdays and 1 weekend day) including measurements of food wastage.

Results

The mean age was 78.7 (SD ± 11.8) years, Body Mass Index (BMI) 23.0 (SD ± 4.2) kg/m²; 50% were women. Energy intake (mean 7.4; SD ± 2.6) MJ/d) was correlated with TEE (mean 7.6; SD ± 1.8 MJ/d; r=0.49, p<0.05). Duration of sleeping ranged from 0.4-12.5 (mean 6.1) hrs/d and time spent lying down was 1.3-16.0 (8.3) hrs/d. On average residents spent 17.9 (6.3-23.4) hrs/d undertaking sedentary activity. TEE was correlated with BMI (r=0.52, p<0.05) and body weight (r=0.81, p<0.001) but inversely related to sleep duration (r=-0.59, p<0.01) and time lying down (r=-0.62, p<0.01). Multiple linear regression analysis revealed that after taking BMI, sleep duration and time spent lying down into account, TEE was no longer correlated with energy intake.

Conclusions

The results show the extent to which body mass, variable activity and sleep patterns may be contributing to TEE and together with reduced energy intake, energy requirements were not satisfied. Thus wearable technology has the potential to offer realtime monitoring to provide appropriate nutrition management that is more person-centred to prevent weight loss in dementia.