Validation of the V(max) metabolic cart in a simulated pediatric model

Innovative Metabolic Rate Sensing Approach for Probing Human Thermal Comfort

The human metabolic rate has attracted increasing interest as it is the most critical parameter in thermal comfort evaluation, a challenging field, while it is always determined imprecisely. The main issue hampering metabolic rate portable measurement is a lack of reliable methods. Current measuring solutions are unsatisfactory because nonportable bulky size systems and disturbance masks are required. This paper proposes a novel metabolic rate measurement model, which we believe is the first of its kind, to accurately identify and predict human metabolism values via wearable technology. Based on a newly developed theory, the designed wearable metabolic rate sensor was fabricated to measure key parameters: heart rate, heat loss, and skin resistance. Together with the body muscle rate, the new final linear metabolic rate model showed easy prediction capability. Eight volunteers were invited for the experiment under three conditions under four activity intensity states. First, the results significantly verify that a linear relationship exists between the metabolic rate tested by the Quark CPET instrument and our proposed model, with a high coefficient of determination (R2 ≈ 0.90). The correlation model is worth mentioning because it coincides with our hypothesis, with at least 95% overall accuracy and less than 2% uncertainty under each condition. Second, the most remarkable finding is that our model is exceedingly suitable (R2 ≈ 0.90) for the same person, regardless of the experimental temperature. Finally, validation is conducted in a wider metabolic range, further strengthening confidence in our metabolic rate estimation approach. In summary, based on an innovative methodology, our novel metabolic rate sensor is wearable, comfortable, real-time achievable, and miniaturized compared with the existing equipment. This paper sheds new light on human metabolic rate measurement and prediction. Furthermore, our approach and designed sensor can be applied to evaluate indoor thermal comfort precisely, thus leading to reduced energy consumption.

Determining energy and protein needs in critically ill pediatric patients: A scoping review

INTRODUCTION

In critically ill pediatric patients, optimal energy and protein intakes are associated with a decreased risk of morbidity and mortality. However, the determination of energy and protein needs is complex. The objective of this scoping review was to understand the extent and type of evidence related to the methods used to determine energy and protein needs in critically ill pediatric patients.

METHODS

An international expert group composed of dietitians, pediatric intensivists, a nurse, and a methodologist conducted the review, based on the Johanna Briggs Institute methodology. Two researchers searched for studies published between 2008 and 2023 in two electronic databases, screened abstracts and relevant full texts for eligibility, and extracted data.

RESULTS

A total of 39 studies were included, mostly conducted in critically ill children undergoing ventilation, to assess the accuracy of predictive equations for estimating resting energy expenditure (REE) (n = 16, 41%) and the impact of clinical factors (n = 22, 56%). They confirmed the risk of underestimation or overestimation of REE when using predictive equations, of which the Schofield equation was the least inaccurate. Apart from weight and age, which were positively correlated with REE, the impact of other factors was not always consistent. No new indirect calorimeter method used to determine protein needs has been validated.

CONCLUSION

This scoping review highlights the need for scientific data on the methods used to measure energy expenditure and determine protein needs in critically ill children. Studies using a reference method are needed to validate an indirect calorimeter.

Indirect Calorimetry Performance Using a Handheld Device Compared to the Metabolic Cart in Outpatients with Cirrhosis

Addressing malnutrition is important to improve health outcomes in outpatients with cirrhosis, yet assessing energy requirements in this population is challenging. Predictive equations of resting energy expenditure (REE) are thought to be unreliable, and traditional indirect calorimetry is expensive and infrequently available for clinical use. The accuracy of REE predictions using a MedGem^® handheld indirect calorimeter, the Harris Benedict Equation (HBE), the Mifflin St. Jeor equation (MSJ), and the gold standard Vmax Encore^® (Vmax) metabolic cart was compared. The REE of cirrhotic pre-liver transplant outpatients was analyzed using each of the four methods. Agreement between methods was calculated using Bland-Altman analysis. Fourteen patients with cirrhosis participated, and were primarily male (71%) and malnourished (subjective global assessment (SGA) B or C 64%). Lin's concordance coefficient (ρC) for MedGem^® vs. Vmax demonstrated poor levels of precision and accuracy (ρC = 0.80, 95% confidence interval 0.55-0.92) between measures, as did the HBE compared to Vmax (ρC = 0.56, 95% confidence interval 0.19-0.79). Mean REE by MedGem^® was similar to that measured by Vmax (-1.5%); however, only 21% of REE measures by MedGem^® were within ±5% of Vmax measures. Wide variability limits the use of MedGem^® at an individual level; a more accurate and feasible method for determination of REE in patients with cirrhosis and malnutrition is needed.

"Cool" Topic: Feeding During Moderate Hypothermia After Intracranial Hemorrhage

BACKGROUND

Therapeutic moderate hypothermia (MH; T _core 33°C-34°C) is being studied for treatment of spontaneous intracerebral hemorrhage (ICH). Nutrition assessment begins with accurate basal metabolic rate (BMR) determination. Although early enteral nutrition (EN) is associated with improved outcomes, it is often deferred until rewarming. We sought to determine the accuracy of predictive BMR equations and the safety and tolerance of EN during MH after ICH.

MATERIALS AND METHODS

Patients were randomized to 72 hours of MH or normothermia (NT; T _core 36°C-37°C). Harris-Benedict (BMR-HB) and Penn-State equation (BMR-PS) calculations were compared with indirect calorimetry (IC) at day (D) 0 and D1-3. Patients with MH received trophic semi-elemental gastric EN. Occurrences of feeding intolerance, gastrointestinal (GI)-related adverse events, and ventilator-associated pneumonia (VAP) were analyzed with a double-sided matched pairs t test.

RESULTS

Thirteen patients with ICH participated (6 MH, 7 NT). Mean time to initiate EN: 29.9 (MH) vs 18.4 (NT) hours ( P = .046). Average daily EN calories received D0-3: 398 (MH) vs 1006 (NT) ( P < .01). Three patients with MH experienced high gastric residuals prior to prokinetic agents, 1 had mild ileus, and 1 patient with NT vomited. No GI-related adverse events were reported. One patient with MH and 1 patient with NT had VAP. Two patients with MH received IC, and from D0 to D1-3, BMR-HB remained stable (1331 kcal), BMR-PS decreased (1511 vs 1145 kcal, P = .5), and IC decreased (1413 vs 985 kcal, P = .2).

CONCLUSIONS

In patients with ICH undergoing MH, resting energy expenditure is decreased and predictive equations overestimate BMR. EN is feasible, although delayed EN initiation, high gastric residuals, and less EN provision are common. Future studies should focus on EN initiation within 24 hours, advanced EN rates, and postpyloric feeds during hypothermia.