Indirect calorimetry as point of care testing

The relationship between caloric intake and clinical outcomes in critically ill patients: A retrospective study

BACKGROUND & AIMS

Despite ongoing research, the optimal nutritional support strategy in the first week of intensive care unit (ICU) stay remains unclear, given the complex interplay of the dynamic metabolic change and evolving nutritional requirements. In this study, we assessed the impact of calorie deficiency during this period on the nutritional care of critically ill patients.

METHODS

In this retrospective study, we examined ICU admissions from January 2018 to September 2021, focusing on patients whose ICU stay exceeded 7 days. Data were collected from days 2-7 of ICU admission. The "average caloric intake (%)" was calculated as the actual calorie intake divided by the calculated calorie requirement over 6 days. Cox proportional hazard models were employed for analyzing the 28-day mortality, supplemented by sensitivity and subgroup analyses.

RESULTS

The analysis of 3544 patients revealed that those receiving less than 60 % of their target calories in the first ICU week experienced higher 28-day mortality (hazard ratio (HR): 1.41, 95 % confidence interval (CI): 1.19-1.67, p < 0.0001). Daily caloric intake below 30 % of the goal from day 5 onward was associated with a gradual increase in mortality risk. Conversely, a significant reduction in 28-day mortality was noted in patients with a daily intake of >80 % starting from day 6.

CONCLUSION

Our study underscores the correlation between caloric deficit (<60 %) in the initial ICU week and heightened mortality risk. It suggests the potential benefits of aggressive nutritional intervention toward the end of the week. These insights offer valuable guidance for clinicians in critical care settings.

Resting Energy Expenditure in Patients with Extreme Obesity: Comparison of the Harris-Benedict Equation with Indirect Calorimetry

Background: The main objective of the work was the analysis and description of data on body composition and resting energy expenditure (REE) values of selected groups of patients with obesity whose REE measurement results using indirect calorimetry reached a level below 95% of the predicted REE calculated using the Harris-Benedict (H-B) equation. The sub-goals were to describe the dependence of body composition on the size of the REE and to find out if the deviations between the number of the total measured REE and the REE calculated using H-B in the adapted group (patients with altered REE values, lower than expected caused by long caloric restriction) are significant. Methods: For the research, 71 (39 women and 32 men) patients treated in obesitology were selected. Patients underwent the measurement of resting metabolism using indirect calorimetry (IC) and body composition measurement on the bioimpedance device and, at the same time, the value of resting metabolism was calculated for everyone using the H-B equation. The whole group was divided into five groups according to the deviation of the measurement using IC and the calculation of the H-B equation. Results: In the total set of examined individuals, there were 32.4% with a reduced REE value compared to the REE calculation according to the H-B equation, which corresponds to 23 individuals. In the adapted group, the average measured REE was 2242 ± 616 kcal compared to the H-B calculation of 2638 ± 713 kcal. Statistically, these results were not significant, but a high case-to-case variation was found. The highest deviation from the H-B predictive calculation was -42% and +43% in the whole research group. The amount of muscle tissue in the adapted group averaged 44.3 ± 11.9 kg and the amount of fat-free mass (FFM) 77.9 ± 20.1 kg. When statistically testing the dependence of REE on FFM and muscle tissue in the adapted group, a strong correlation was found. Conclusions: The H-B equation alone is not suitable for setting a suitable diet therapy for an individual with obesity. In order to select and characterize a group of adapted individuals, it will be necessary to use other methods or a larger research sample, and preferably examine and divide patients with specific comorbidities or include their health status.

Bioelectrical Impedance Analysis to Assess Energy Expenditure in Critically Ill Patients: A Cross-Sectional Study

BACKGROUND

Evaluating energy expenditure is important for establishing optimal goals for nutrition treatment. However, indirect calorimetry, the reference standard for measuring energy expenditure, is difficult to apply widely in clinical practice.

OBJECTIVE

To test the consistency of bioelectrical impedance analysis (BIA) relative to indirect calorimetry for evaluating energy expenditure in critically ill patients.

METHODS

A cross-sectional study of 140 critically ill adult patients was conducted. Within 24 hours of a patient being transferred to the intensive care unit, trained researchers assessed the patient's energy expenditure by use of BIA and indirect calorimetry simultaneously. Consistency of the 2 measurements was detected by intraclass correlation coefficients with a 2-way random-effects model. Factors affecting consistency were analyzed.

RESULTS

Median energy expenditure measured by indirect calorimetry was 1430.0 kcal/d (IQR, 1190.5-1650.8 kcal/d). Median energy expenditure measured by BIA was 1407.0 kcal/d (IQR, 1248.5-1563.5 kcal/d). The correlation coefficient between indirect calorimetry and BIA was 0.813 (95% CI, 0.748-0.862; P < .001). The consistency of the 2 measurements was lower in patients with comorbidities than in those without (P = .004).

CONCLUSIONS

Results of BIA were highly consistent with indirect calorimetry assessments of energy expenditure in critically ill patients. Few factors except comorbidity affect the accuracy of BIA when assessing energy expenditure. Therefore, as a low-cost, easy-to-use, and noninvasive method, BIA is a valuable clinical tool for assessing energy expenditure in critically ill patients.

Longitudinal analysis of caloric requirements in critically ill trauma patients: a retrospective cohort study

PURPOSE

Nutrition is of paramount importance in critically ill trauma patients. However, adequate supply is difficult to achieve, as caloric requirements are unknown. This study investigated caloric requirements over time, based on indirect calorimetry, in critically ill trauma patients.

METHODS

Retrospective cohort study at a tertiary trauma center including critically ill trauma patients who underwent indirect calorimetry 2012-2019. Caloric requirements were assessed as resting energy expenditure (REE) during the intensive care unit stay up to 28 days and analyzed in patient-clustered linear regression analysis.

RESULTS

A total of 129 patients were included. Median REE per day was 2376 kcal. The caloric intake did not meet REE at any time with a median daily deficit of 1167 kcal. In univariable analysis, ISS was not significantly associated with REE over time (RC 0.03, p = 0.600). Multivariable analysis revealed a significant REE increase (RC 0.62, p < 0.001) and subsequent decrease (RC - 0.03, p < 0.001) over time. Age < 65 years (RC 2.07, p = 0.018), male sex (RC 4.38, p < 0.001), and BMI ≥ 35 kg/m2 (RC 6.94, p < 0.001) were identified as independent predictors for higher REE over time. Severe head trauma was associated with lower REE over time (RC - 2.10, p = 0.030).

CONCLUSION

In critically ill trauma patients, caloric requirements significantly increased and subsequently decreased over time. Younger age, male sex and higher BMI were identified as independent predictors for higher caloric requirements, whereas severe head trauma was associated with lower caloric requirements over time. These results support the use of IC and will help to adjust nutritional support in critically ill trauma patients.

High carbohydrate is preferable to high lipid parenteral nutrition in healthy dogs undergoing prolonged sedation

Parenteral nutrition (PN) is commonly used in intensive care units (ICUs) and is associated with earlier hospital outcome. However, there is scarcity of information about the metabolic effects of PN caloric distribution for dogs. Considering the high tolerance of dogs to lipids and, also, that hospitalized animals usually present insulin resistance, PN formulation with high fat instead high glucose can provide metabolic benefits in this specie. This study evaluated two PN protocols, based on high lipid or high carbohydrate in 12 healthy dogs under sedation/ventilation during 24 h. For baseline data, blood samples were collected 24 h before the study beginning. After fasting, the dogs were anesthetized and put under mechanical ventilation without energy support for 12 h to obtain: daily energy expenditure (DEE), respiratory quotient (RQ), oxygen consumption (VO2), carbon dioxide production (VCO2), lactate, glucose, cholesterol, and triglycerides concentrations. After, the dogs were allocated into two groups: lipid-based energy group (LEG) and carbohydrate-based energy group (CEG). Both groups received the PN infusions at a rate of 3 mL/kg/h for 12 h. Blood tests were performed 12, 24, and 48 h after infusion's completion. VO2 increased after PN in LEG, increasing energy expenditure compared to CEG. RQ remained close to 1 in CEG, indicating carbohydrate preferential consumption. Triglycerides increased in both groups after propofol infusion, remaining higher in LEG until the end of the evaluation. Glycaemia increased in CEG compared to baseline. In conclusion, both PN protocols can be used in healthy animals undergoing prolonged sedation protocols. However, high lipid PN had higher VO2 and DEE, and resulted in higher triglycerides concentrations and lower glycaemia indexes than carbohydrate, making high carbohydrate PN preferable to high lipid PN. Therefore, for use in critically ill patients, the data obtained in this study should be extrapolated, taking into consideration the specificity of each case.

An evaluation of intensive care nurses' performance of indirect calorimetry measurements

BACKGROUND

Indirect calorimetry (IC) is the gold standard to monitor energy expenditure in critically ill patients. In several intensive care units (ICUs), nurses are responsible for carrying out the measurements.

AIM

The aim of this study was to assess nurses' perception of their involvement in IC.

STUDY DESIGN

This was a prospective survey conducted in the surgical ICU of a French university hospital after 18 months of use of the Q-NRG + ® calorimeter (COSMED©, Italy). All nurses who have used the calorimeter in the previous 6 months in this ICU were questioned through a questionnaire about their theoretical and practical knowledge and experience in using it.

RESULTS

The participation rate was 93% (28/30 surveyed). All the respondents understood the objectives of performing an IC and 23 of them (82%) had used the device at least once in the previous 6 months. All the users thought it was pertinent that ICU nurses were in charge of the IC measurements, 16 of them (70%) reported having been formally trained, mostly by a colleague, and 17 (77%) felt comfortable with the device after 2 to 5 uses. The five non-users (8%) did not have the opportunity to do so. Theoretical and practical knowledge could be improved as only 5 of the users (22%) declared to know the main criteria of reliability of the IC measurement and 4 of them (18%) declared to know the maintenance and cleaning protocol of the device.

CONCLUSION

Nurses quickly felt comfortable with the Q-NRG + ® in this ICU. Formal initial and ongoing training of all staff completing IC is essential to perform IC measurements safely and to obtain reliable and interpretable results in practice.

RELEVANCE TO CLINICAL PRACTICE

Involving the nursing team in nutritional care, even if it is technical, seems to bring satisfaction in terms of overall patient care.

Resting energy expenditure, body composition, and metabolic alterations in breast cancer survivors vs. healthy controls: a cross-sectional study

PURPOSE

This study aimed to investigate the difference in absolute and fat free mass (FFM)-adjusted resting energy expenditure (mREE) and body composition (body weight, fat mass (FM), FFM) between breast cancer survivors (BCs) and controls. Correlations with body composition were analyzed. We examined if survival year, or being metabolically dysfunctional were predictive variables.

METHODS

A cross-sectional analysis was conducted on 32 BCs ≤5 years post treatment and 36 healthy controls. Indirect calorimetry measured absolute mREE. Body composition was determined by BOD POD. FFM-adjusted mREE was calculated (mREE/FFM). The Harris-Benedict equation was used to predict REE and determine hyper-/hypometabolism (mREE/pREE). The database of the multidisciplinary breast clinic of the University Hospital of Antwerp was consulted for survival year and metabolic dysfunctions.

RESULTS

BCs have similar absolute mREE and greater FFM-adjusted mREE compared to controls. Absolute mREE and body composition between BCs differed; adjusted mREE was similar. FFM correlated significantly with absolute mREE in BCs. A significant interaction term was found between survival year and FM for absolute mREE.

CONCLUSION

BCs have similar absolute mREE, but higher FFM-adjusted mREE. Differences in body composition between BCs are suggested to cause inter-individual variations. We suggest that increased FFM-adjusted mREE is caused by metabolic stress related to cancer/treatment. Accurate measurement of REE and body composition is advised when adapting nutritional strategies, especially in patients at risk for developing metabolic dysfunctions.

Underfeeding Alters Brain Tissue Synthesis Rate in a Rat Brain Injury Model

Brain injuries (BI) are highly disruptive, often having long lasting effects. Inadequate standard of care (SOC) energy support in the hospital leads to dietary energy deficiencies in BI patients. However, it is unclear how underfeeding (UF) affects protein synthesis post-BI. Therefore, in a rat model, we addressed the issue of UF on the protein fractional synthesis rate (fSR) post-BI. Compared to ad libitum (AL)-fed animals, we found that UF decreased protein synthesis in hind-limb skeletal muscle and cortical mitochondrial and structural proteins (p ≤ 0.05). BI significantly increased protein synthesis in the left and right cortices (p ≤ 0.05), but suppressed protein synthesis in the cerebellum (p ≤ 0.05) as compared to non-injured sham animals. Compared to underfeeding alone, UF in conjunction with BI (UF+BI) caused increased protein synthesis rates in mitochondrial, cytosolic, and whole-tissue proteins of the cortical brain regions. The increased rates of protein synthesis found in the UF+BI group were mitigated by AL feeding, demonstrating that caloric adequacy alleviates the effects of BI on protein dynamics in cortical and cerebellar brain regions. This research provides evidence that underfeeding has a negative impact on brain healing post-BI and that protein reserves in uninjured tissues are mobilized to support cortical tissue repair following BI.

Nutrition Intervention Informed by Indirect Calorimetry Compared to Predictive Equations to Achieve Weight Goals in Geriatric Rehabilitation Inpatients: The NEED Study

OBJECTIVES

To assess if nutritional interventions informed by indirect calorimetry (IC), compared to predictive equations, show greater improvements in achieving weight goals, muscle mass, strength, physical and functional performance.

DESIGN

Quasi-experimental study.

SETTING AND PARTICIPANTS

Geriatric rehabilitation inpatients referred to dietitian.

INTERVENTION AND MEASUREMENTS

Patients were allocated based on admission ward to either the IC or equation (EQ) group. Measured resting metabolic rate (RMR) by IC was communicated to the treating dietitian for the IC group but concealed for the EQ group. Achieving weight goals was determined by comparing individualised weight goals with weight changes from inclusion to discharge (weight gain/loss: >2% change, maintenance: ≤2%). Muscle mass, strength, physical and functional performance were assessed at admission and discharge. Food intake was assessed twice over three-days at inclusion and before discharge using plate waste observation.

RESULTS

Fifty-three patients were included (IC n=22; EQ n=31; age: 84.3±8.4 years). The measured RMR was lower than the estimated RMR within both groups [mean difference IC -282 (95%CI -490;-203), EQ -273 (-381;-42) kcal/day)] and comparable between-groups (median IC 1271 [interquartile range 1111;1446] versus EQ 1302 [1135;1397] kcal/day, p=0.800). Energy targets in the IC group were lower than the EQ group [mean difference -317 (95%CI -479;-155) kcal/day]. There were no between-group differences in energy intake, achieving weight goals, changes in muscle mass, strength, physical and functional performance.

CONCLUSIONS

In geriatric rehabilitation inpatients, nutritional interventions informed by IC compared to predictive equations showed no greater improvement in achieving weight goals, muscle mass, strength, physical and functional performance. IC facilitates more accurate determination of energy targets in this population. However, evidence for the potential benefits of its use in nutrition interventions was limited by a lack of agreement between patients' energy intake and energy targets.

Fractional Gluconeogenesis: A Biomarker of Dietary Energy Adequacy in a Rat Brain Injury Model

Patients treated for traumatic brain injury (TBI) are in metabolic crises because of the trauma and underfeeding. We utilized fractional gluconeogenesis (fGNG) to assess nutritional adequacy in ad libitum-fed and calorically-restricted rats following TBI. Male Sprague-Dawley individually housed rats 49 days of age were randomly assigned into four groups: ad libitum (AL) fed control (AL-Con, sham), AL plus TBI (AL+TBI), caloric restriction (CR) control (CR-Con, sham), and CR plus TBI (CR+TBI). From days 1-7 animals were given AL access to food and water containing 6% deuterium oxide (D₂O). On day 8, a pre-intervention blood sample was drawn from each animal, and TBI, sham injury, and CR protocols were initiated. On day 22, the animals were euthanized, and blood was collected to measure fGNG. Pre-intervention, there was no significant difference in fGNG among groups (p ≥ 0.05). There was a significant increase in fGNG due to caloric restriction, independent of TBI (p ≤ 0.05). In addition, fGNG may provide a real-time, personalized biomarker for assessing patient dietary caloric needs.

Methodological Aspects of Indirect Calorimetry in Patients with Sepsis-Possibilities and Limitations

The aim of the review was to analyse the challenges of using indirect calorimetry in patients with sepsis, including the limitations of this method. A systematic review of the literature was carried out. The analysis concerned the methodology and presentation of research results. In most studies assessing energy expenditure, energy expenditure was expressed in kcal per day (n = 9) and as the mean and standard deviation (n = 7). Most authors provided a detailed measurement protocol, including measurement duration (n = 10) and device calibration information (n = 7). Ten papers provided information on the day of hospitalisation when the measurements were obtained, nine on patient nutrition, and twelve on the criteria for inclusion and exclusion of participants from the study. Small study group sizes and study at a single centre were among the most cited limitations. Studies assessing energy expenditure in patients with sepsis by indirect calorimetry differ in the methodology and presentation of results, and their collective analysis is difficult. A meta-analysis of the results could enable multi-site and large patient evaluation. Standardisation of protocols and presentation of all collected data would enable their meta-analysis, which would help to achieve greater knowledge about metabolism in sepsis.

Effects of physical therapy with neuromuscular electrical stimulation in acute and late septic shock patients: A randomised crossover clinical trial

BACKGROUND

Patients with sepsis and immobility in the intensive care unit are associated with muscle weakness, and early mobilisation can counteract it. However, during septic shock, mobilisation is often delayed due to the severity of the illness. Neuromuscular electrical stimulation (NMES) may be an alternative to mobilise these patients early. This study aims to identify whether NMES performed within the first 72 hours of septic shock diagnosis or later is safe from a metabolic perspective.

METHODS

This is the analysis of two randomised controlled crossover studies. Patients with acute septic shock (within the first 72 hours of diagnosis) and sepsis and septic shock in the late phase (after 72 hours of diagnosis) were eligible. Patients were submitted in a random order to the intervention protocol (dorsal decubitus position with the lower limbs raised and NMES) and control (dorsal decubitus position with the lower limbs raised without NMES). The patients were allocated in group 1 (intervention and control) or group 2 (control and intervention) with a wash-out period of 4 to 6 hours. Metabolic variables were evaluated by indirect calorimetry.

RESULTS

Sixteen patients were analysed in the acute septic shock study and 21 in the late sepsis/septic shock study. There were no significant differences between Oxygen Consumption (VO2) values in the acute phase of septic shock when the baseline period, intervention, and control protocols were compared (186.59 ± 46.10; 183.64 ± 41.39; 188.97 ± 44.88, p>0.05- expressed in mL/Kg/min). The same was observed when the VO2 values in the late phase were compared (224.22 ± 53.09; 226.20 ± 49.64; 226.79 ± 58.25, p>0.05). The other metabolic variables followed the same pattern, with no significant differences between the protocols. When metabolic variables were compared between acute to late phase, significant differences were observed (p<0.05).

CONCLUSIONS

As metabolic rates in septic shock patients had no increase during NMES, either in the first 72 hours of diagnosis or later, NMES can be considered safe from a metabolic viewpoint, even despite the higher metabolic demand in the acute phase of shock.

TRIAL REGISTRATION

NCT03193164; NCT03815994. Registered on June 5, 2017; November 13, 2018 (clinicaltrials.gov/).

The effect of indirect calorimetry guided isocaloric nutrition on mortality in critically ill patients-a systematic review and meta-analysis

Indirect calorimetry (IC)-guided nutrition might positively affect the clinical outcome of critically ill patients. In this systematic review and meta-analysis, our objective was to assess the benefit of isocaloric nutrition guided by IC, compared to hypocaloric nutrition, for critically ill patients admitted to the intensive care unit (ICU). We performed a systematic review of all randomized controlled trials published through January 2021, assessing the benefit of isocaloric nutrition guided by IC. The primary outcome was 28-day all-cause mortality. Secondary outcomes were ICU and 90-day all-cause mortality, rate of nosocomial infections, and adverse events. Four trials evaluating 1052 patients were included. Patients treated with isocaloric nutrition had a lower 28-day mortality rate (risk ratio (RR) 0.79, 95% confidence interval (CI) 0.63-0.99, P = 0.04). No between-group difference was found in ICU and 90-day mortality (RR 0.92, 95% CI 0.68-1.23, P = 0.56 and RR 0.88, 95% CI 0.72-1.07; P = 0.2, respectively) and in the rate of nosocomial infections (RR 1.15, 95% CI 0.77-1.72, P = 0.51). A pooled analysis of studies that evaluated the benefit of isocaloric nutrition guided by IC, for critically ill patients in the ICU, has shown reduced 28-day mortality. However, there was no difference in 90-day mortality and nosocomial infection rate.

Energy expenditure and feeding practices and tolerance during the acute and late phase of critically ill COVID-19 patients

BACKGROUND & AIMS

Different metabolic phases can be distinguished in critical illness, which influences nutritional treatment. Achieving optimal nutritional treatment during these phases in critically ill patients is challenging. COVID-19 patients seem particularly difficult to feed due to gastrointestinal problems. Our aim was to describe measured resting energy expenditure (mREE) and feeding practices and tolerance during the acute and late phases of critical illness in COVID-19 patients.

METHODS

Observational study including critically ill mechanically ventilated adult COVID-19 patients. Indirect calorimetry (Q-NRG+, Cosmed) was used to determine mREE during the acute (day 0-7) and late phase (>day 7) of critical illness. Data on nutritional intake, feeding tolerance and urinary nitrogen loss were collected simultaneously. A paired sample t-test was performed for mREE in both phases.

RESULTS

We enrolled 21 patients with a median age of 59 years [44-66], 67% male and median BMI of 31.5 kg/m2 [25.7-37.8]. Patients were predominantly fed with EN in both phases. No significant difference in mREE was observed between phases (p = 0.529). Sixty-five percent of the patients were hypermetabolic in both phases. Median delivery of energy as percentage of mREE was higher in the late phase (94%) compared to the acute phase (70%) (p = 0.001). Urinary nitrogen losses were significant higher in the late phase (p = 0.003).

CONCLUSION

In both the acute and late phase, the majority of the patients were hypermetabolic and fed enterally. In the acute phase patients were fed hypocaloric whereas in the late phase this was almost normocaloric, conform ESPEN guidelines. No significant difference in mREE was observed between phases. Hypermetabolism in both phases in conjunction with an increasing loss of urinary nitrogen may indicate that COVID-19 patients remain in a prolonged acute, catabolic phase.

Energy expenditure and indirect calorimetry in critical illness and convalescence: current evidence and practical considerations

The use of indirect calorimetry is strongly recommended to guide nutrition therapy in critically ill patients, preventing the detrimental effects of under- and overfeeding. However, the course of energy expenditure is complex, and clinical studies on indirect calorimetry during critical illness and convalescence are scarce. Energy expenditure is influenced by many individual and iatrogenic factors and different metabolic phases of critical illness and convalescence. In the first days, energy production from endogenous sources appears to be increased due to a catabolic state and is likely near-sufficient to meet energy requirements. Full nutrition support in this phase may lead to overfeeding as exogenous nutrition cannot abolish this endogenous energy production, and mitochondria are unable to process the excess substrate. However, energy expenditure is reported to increase hereafter and is still shown to be elevated 3 weeks after ICU admission, when endogenous energy production is reduced, and exogenous nutrition support is indispensable. Indirect calorimetry is the gold standard for bedside calculation of energy expenditure. However, the superiority of IC-guided nutritional therapy has not yet been unequivocally proven in clinical trials and many practical aspects and pitfalls should be taken into account when measuring energy expenditure in critically ill patients. Furthermore, the contribution of endogenously produced energy cannot be measured. Nevertheless, routine use of indirect calorimetry to aid personalized nutrition has strong potential to improve nutritional status and consequently, the long-term outcome of critically ill patients.

Validation and improvement of the predictive equation for resting energy expenditure in advanced gastrointestinal cancer

OBJECTIVES

The usual predictive equations for estimating resting energy expenditure (REE) seem to be associated with significant inaccuracy in patients with advanced cancer. Recently, our group developed a predictive equation for patients with advanced head and neck cancer, showing a better accuracy when compared with indirect calorimetry. The aim of this study was to validate this predictive equation and, if necessary, to elaborate a new predictive equation for patients with advanced gastrointestinal (GI) cancer.

METHODS

This was a retrospective, unicentric observational study. Data regarding the characteristics of the study were collected using an electronic medical record from June 2016 to January 2018. The nutritional status was calculated by the body mass index (BMI). Patients with nutritional risk, by the Nutritional Risk Screening 2002, were subjectively evaluated in relation to the nutritional status by the Patient-Generated Subjective Global Assessment (PG-SGA). Sarcopenia was defined as fat-free mass index ≤17.4 kg/m² for men and ≤15 kg/m² for women. Body composition and phase angle values were evaluated by electrical bioimpedance. REE was measured by indirect calorimetry.

RESULTS

The study included 109 patients with advanced GI tract cancer. Most were male (72.5%), ≥60 y of age (61.5%), and had cancer in the esophagus region (62.4%). Most patients had not undergone any treatment at the time of the examination. Regarding nutritional characteristics, the majority of the patients were malnourished by BMI (71.6%), with a deficit of lean mass (79.8%), sarcopenia (83.5%), and a phase angle below the fifth percentile for age, sex, and BMI, showing in addition to a poor nutritional condition, an impaired cellular integrity. Most of the patients were hypermetabolic (56.9%) and their caloric intake in the preceding 3 d was insufficient in 43.1%. Through the intraclass correlation coefficient (ICC), it was possible to observe the satisfactory agreement between the REE measured by the gold standard (calorimetry) versus the Souza-Singer's formula (ICC, 0.730; 95% confidence interval, 0.659-0.789; P < 0.001). When we did the multiple linear regression model, we figured that in this group of patients with GI cancer, only lean mass, phase angle, and sex were the age-adjusted independent variables that influenced REE, which was different from the Souza-Singer formula. This way a new prediction formula for this population has been created and needs to be validated.

CONCLUSION

A new equation considering phase angle and body composition can improve the accuracy of the predictive equation.

Energy Expenditure in Critically Ill Adult Patients With Acute Brain Injury: Indirect Calorimetry vs. Predictive Equations

Introduction: Predictive equations (PE) are used in lieu of indirect calorimetry (IC) due to cost and limited resources; however, these equations may not be as accurate as IC in estimating resting energy expenditure (REE) in critically ill patients, putting them at risk of malnutrition. The purpose of this study is to compare predicted and measured energy expenditure (MEE) in critically ill adults with acute brain injury.

Materials and Methods: This was a retrospective review of adult patients admitted to the Neurosciences ICU with acute brain injury between May 1st, 2014 and April 1st, 2016 who had IC performed. The Harris Benedict (HBE), Penn State University, and Mifflin St Jeor (MSJ) PE were used in comparison to IC results. Subgroup analyses stratified patients based on BMI and type of acute brain injury.

Results: One hundred and forty-four patients met inclusion criteria. Comparing predicted and MEE found no significant difference (p = 0.1). High degrees of interpatient variability were discovered, with standard deviations ranging from 17 to 29% of each PE. Pearson's correlations indicated weak associations when HBE, Penn State, and MSJ were individually compared to MEE (r = 0.372, 0.409, and 0.372, respectively). A significant difference was found between predicted and MEE in patients with a BMI < 30 kg/m² (p < 0.01) and in those with aneurysmal subarachnoid hemorrhage (p < 0.01).

Discussion: Due to interpatient variability that exists among REE of critically ill patients with acute brain injury, IC should be used when feasible.

Indirect Calorimetry in Clinical Practice

Indirect calorimetry (IC) is considered as the gold standard to determine energy expenditure, by measuring pulmonary gas exchanges. It is a non-invasive technique that allows clinicians to personalize the prescription of nutrition support to the metabolic needs and promote a better clinical outcome. Recent technical developments allow accurate and easy IC measurements in spontaneously breathing patients as well as in those on mechanical ventilation. The implementation of IC in clinical routine should be promoted in order to optimize the cost–benefit balance of nutrition therapy. This review aims at summarizing the latest innovations of IC as well as the clinical indications, benefits, and limitations.