Introduction of adult cats to indirect calorimetry respiration chambers causes increased energy expenditure and respiratory quotient that decrease following acclimation

OBJECTIVE To replicate a previously defined behavioral procedure to acclimate adult cats to temporary restriction in indirect calorimetry chambers and measure energy expenditure and respiratory quotient changes during acclimation. ANIMALS 8 healthy adult cats (4 spayed females, and 4 neutered males; mean ± SEM age, 2.5 ± 1.5 years; mean body weight, 4.8 ± 1.8 kg). PROCEDURES Cats underwent a 13-week incremental acclimation procedure whereby cats were acclimated to the chambers in their home environment (weeks 1 to 3), to the study room (weeks 4 to 6), and to increasing lengths of restriction within their home environment (weeks 7 to 8) and the chambers (weeks 9 to 13). Cat stress score, respiratory rate, fearfulness (assessed with a novel object test), energy expenditure, and respiratory quotient were measured. Data were analyzed by use of a repeated-measures mixed model. RESULTS Stress, based on cat stress scores, fearfulness, and respiration, peaked at weeks 4, 9, and 10 but returned to baseline levels by week 11. Energy expenditure and respiratory quotient peaked at weeks 10 and 11, respectively, but were reduced significantly by weeks 11 and 13, respectively. All cats returned to baseline by the end of the study and were deemed fully acclimated. CLINICAL RELEVANCE Changes in perceived stress level, energy expenditure, and respiratory quotient at various stages of the acclimation procedure suggest that stress should be considered a significant variable in energy balance measurements when indirect calorimetry is used in cats. An incremental acclimation procedure should therefore be used to prepare cats for the temporary space restriction necessary for indirect calorimetry studies.

A Comparison between Continuous Indirect Calorimetry and Single Weight-Based Formula in Estimating Resting Energy Expenditure in Nutritional Therapy: A Prospective Randomized Controlled Study in Critically Ill Patients

Optimal nutritional therapy is important to improve outcome in critically ill population in an intensive care unit (ICU). Although indirect calorimetry (IC) is currently a gold standard for resting energy expenditure (REE) measurement, yet it is still not routinely used in the ICU. A total of 146 mechanically ventilated patients were randomised to receive enteral nutrition (EN) with energy targeted based on continuous indirect calorimetry (IC) measurements (IC group, n=73) or according to 25 kcal/kg/day (SWB group, n=73). Patient characteristics were equally distributed and the IC group showed lower mean measured REE (1668.1 + 231.7 vs 1512.0 + 177.1 kcal, p<0.001). Results also showed a significant deficiency in the daily (-148.8 + 105.1 vs. -4.99 + 44.0 kcal, p<0.001) and total cumulative energy balances (-1165.3 + 958.1 vs. 46.5 + 369.5 kcal, p<0.001) in the SWB group as compared to the IC group. From the Kaplan-Meier survival analysis, we found that ICU mortality was significantly lower in the IC group with better survival probability compared to the SWB group (log-rank test, p = 0.03). However, both groups showed comparable results in terms of ICU length of stay, duration of mechanical ventilation and incidence of feeding intolerance. In conclusion, this study showed that tightly supervised nutritional therapy based on continuous IC measurement provides significantly less mean daily and cumulative energy deficits as well as significantly reduced ICU mortality rate.

Comparative Analysis of the Indirect Calorimetry and the Metabolic Power Method to Calculate Energy Expenditure in Team Handball

Monitoring physical activity, e.g., training load and energy expenditure (EE), is important to optimize the training process in various sports. Especially in team handball, where there is little information about EE in training and competition. The objective of the study was to compare EE in team handball derived from a respiratory gas exchange analysis (spiroergometry) and a local position measurement (LPM) system. Eleven participants completed a validated, team handball game-based performance test and wore a portable spiroergometry system (K5 Cosmed) and an LPM transponder (Catapult ClearSky T6). EE was determined via indirect calorimetry for spiroergometry data and via the metabolic power model for EE for LPM data. EE estimated via the metabolic power model was −66 to −63 ± 12% lower than via indirect calorimetry (p < 0.001, pη2 = 0.97). No correlation was found for the overall test (r = 0.32, p = 0.34), nor for every single heat (r ≤ 0.44, 0.18 ≤ p ≤ 0.99). Therefore, regression analyses predicting spiroergometry data based on LPM data were not feasible. In line with previous studies, the metabolic power model for EE in team handball (including short-distance movements, great accelerations, and non-locomotive actions) is not suitable.

Analysis of energy expenditure of skiers across the preparatory phase

Energy expenditure was calculated at rest and during physical activity by indirect calorimetry using the Oxyson Pro system in 55 highly elite skiers. The results showed that in 75% of athletes, the measured rest energy expenditure were higher than the calculated rest energy expenditure by 20% and was 2139±363 kcal/day. Daily energy expenditure was 5347±907 kcal. In the structure of rest energy expenditure the part of carbohydrates was 67 % and fats was 33%. Generally, energy expenditure was more 5000 kcal. In addition, in our study, it was observed a progressive increase of contribution of carbohydrate oxidation in energy expenditure during high-intensity exercise. Key words: energy expenditure, high-intensity exercise, carbohydrates, fats, skiers, indirect calorimetry.

How much does it cost? Teaching physiology of energy metabolism in mice using an indirect calorimetry system in a practical course for veterinary students

In endothermic mammals total energy expenditure (EE) is composed of basal metabolic rate (BMR), energy spent for muscle activity, thermoregulation, any kind of production (such as milk, meat or egg production) and the thermic effect of feeding. The BMR is predominantly determined by body mass and the surface to volume ratio of the body. The EE can be quantified either by direct or indirect calorimetry. Direct calorimetry measures the rate of heat loss from the body, whereas indirect calorimetry measures oxygen consumption and carbon dioxide production and calculates heat production from oxidative nutrient combustion. A deep and sustainable understanding of EE in animals is crucial for veterinarians in order to properly calculate and evaluate feed rations, during special circumstances such as anaesthesia or in situations with increased energy demands as commonly seen in high yielding livestock. The practical class described in this manuscript provides an experimental approach to understand how EE can be measured and calculated by indirect calorimetry. Two important factors that affect the EE of animals (the thermic effect of feeding and the effect of ambient temperature) are measured. A profound knowledge about the energy requirements of animal life and its measurement is also relevant for education in general biology, animal and human physiology and nutrition. Therefore, this teaching unit can equally well be implemented in other areas of life sciences.

Changes in carbon dioxide production and oxygen uptake evaluated using indirect calorimetry in mechanically ventilated patients with sepsis

Background Several clinical guidelines recommend monitoring blood lactate levels and central venous oxygen saturation for hemodynamic management of patients with sepsis. We hypothesized that carbon dioxide production (VCO2) and oxygen extraction (VO2) evaluated using indirect calorimetry (IC) might provide additional information to understand the dynamic metabolic changes in sepsis. Methods Adult patients with sepsis who required mechanical ventilation in the intensive care unit (ICU) of our hospital between September 2019 and March 2020 were prospectively enrolled. Sepsis was diagnosed according to Sepsis-3. Continuous measurement of VCO2 and VO2 using IC for 2 h was conducted within 24 h after tracheal intubation, and the changes in VCO2 and VO2 over 2 h were calculated as the slopes by linear regression analysis. Furthermore, temporal lactate changes were evaluated. The primary outcome was 28-day survival. Results Thirty-four patients with sepsis were enrolled, 26 of whom survived 76%. Significant differences in the slope of VCO2 (− 1.412 vs. − 0.446) (p = 0.012) and VO2 (− 2.098 vs. − 0.851) (p = 0.023) changes were observed between non-survivors and survivors. Of note, all eight non-survivors and 17 of the 26 survivors showed negative slopes of VCO2 and VO2 changes. For these patients, 17 survivors had a median lactate of − 2.4% changes per hour (%/h), whereas non-survivors had a median lactate of 2.6%/hr (p = 0.023). Conclusions The non-survivors in this study showed temporal decreases in both VCO2 and VO2 along with lactate elevation. Monitoring the temporal changes in VCO2 and VO2 along with blood lactate levels may be useful in predicting the prognosis of sepsis.