General principles of resuscitation and supportive care: Burns
David E. Wesson, Bindi Naik-Mathuria in Pediatric Trauma, 2017
Although successful delivery of nutrition can be challenging, no gold standard for monitoring nutritional status after pediatric burn injury has been established. Due to the risks associated with underfeeding and malnutrition in burned children, monitoring is recommended to ensure that the elevated metabolic demands are met. Prealbumin, C-reactive protein, transferrin, and indirect calorimetry have all been suggested as markers but have not shown a consistent association with nutrition status [103, 104]. Monitoring of laboratory trends over time is preferred over reliance on a single value. Indirect calorimetry can be used to estimate energy expenditures by evaluating oxygen consumption or carbon dioxide production. When available, indirect calorimetry has been recommended for monitoring energy requirements after burn injury [105, 106]. Indirect calorimetry, however, can be influenced by metabolic derangements often seen in critically ill patients, limiting its usefulness in these settings [106]. The combined use of laboratory trends and indirect calorimetry monitoring is an ideal approach for evaluation of nutritional status in the burn-injured child requiring nutritional support.
Biomarker for Energy Intake
Dale A. Schoeller, Margriet S. Westerterp-Plantenga in Advances in the Assessment of Dietary Intake, 2017
The reference technique for the assessment of REE and AEE is indirect calorimetry. In indirect calorimetry the energy production is calculated from oxygen consumption, carbon dioxide production, and urine-nitrogen loss. The basis of the calculation is the gaseous exchange and energy release from the metabolized carbohydrate, fat, and protein. For the measurement of REE, a subject is observed under standard conditions excluding TEF and AEE. For the measurement of AEE, the subject is observed under free-living conditions. Then, total energy expenditure is measured with the doubly-labeled water technique, based on the measurement of carbon dioxide production as described in the foregoing chapter, and AEE is derived from total energy expenditure adjusted for REE. Measurements of REE with indirect calorimetry allowed the development of prediction equations for REE based on subject characteristics including height, age, weight, and gender. The alternative for doubly-labeled water assessed AEE is an accelerometer for body movement registration as validated with doubly-labeled water assessed AEE as a reference.
Basic Thermal Physiology: What Processes Lead to the Temperature Distribution on the Skin Surface
Kurt Ammer, Francis Ring in The Thermal Human Body, 2019
Another important chemical element necessary for humans and animals is oxygen, which is inhaled with air, transported through the gas-exchanging surface of the lung to the capillary net adjacent to the pulmonary alveoli, bound to haemoglobin of red blood cells, which act as oxygen carrier and is delivering oxygen to the cells of all tissues. The principle to release internal energy of chemical compounds through oxidation was already mentioned in Chapter 2. Measuring the uptake of oxygen and/or the elimination of carbon dioxide, and the conversion of these values to an equivalent quantity of heat is the most common method of indirect calorimetry. The calorific equivalent of a litre of oxygen is approximately 20 kJ of heat. Oxygen consumption has a key role in energy metabolism, which is defined as the sum of the chemical changes in living matter in which energy is transformed. The maximum rate at which an organism can take up oxygen is termed maximum oxygen consumption, VO2max, expressed in SI units as ml·s−1, but conventionally ml per min and 1 per min are the used units. Determination of this parameter requires very high motivation of the subject and can probably be done only on humans. Criteria used to show that a human subject has reached the VO2max, although not yet agreed upon, include an indication of no further increase in oxygen uptake during further increase in workload. More details of metabolic heat generation will be described later.
Circadian rhythmicity of body temperature and metabolism
Published in Temperature, 2020
Roberto Refinetti
Indirect calorimetry is based on the measurement of oxygen consumed (and carbon dioxide produced) by the organism and on the chemical properties of oxidation. Knowledge of the stoichiometric properties of oxidative processes makes it possible to calculate the amount of nutrient being combusted, and the amount of heat being released, by measuring only the amount of oxygen being consumed. To measure the concentration of oxygen in the air used by the organism (as well as the concentration of carbon dioxide, if greater accuracy is needed in the computation of metabolic rate), gas analyzers are employed. Suppliers of gas analyzers for biomedical research include Servomex (Crowborough, England), Columbus Instruments (Columbus, Ohio), Sable Systems International (North Las Vegas, Nevada), and Qubit Systems (Kingston, Canada). For data collection the animal of interest is placed inside a sealed chamber, and a measured volume of air is passed through the chamber. By determining the difference in the concentration of oxygen in the air that enters the chamber and in the air that leaves the chamber, one can determine the percentage of oxygen consumed by the organism. The percentage can then be converted into amount of oxygen (and corresponding amount of heat produced) if the exact flow of air through the chamber is known [486,487]. A computerized system that activates the air-switch valves and collects the data is needed for the monitoring of metabolism with adequate temporal resolution for long-term studies of circadian rhythmicity.
Physical activity measurement accuracy in advanced chronic lung disease
Published in Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 2018
Satvir S. Dhillon, Robert D. Levy, Pearce G. Wilcox, Jordan A. Guenette, Bradley S. Quon, Christopher J. Ryerson, Pat G. Camp
Minute-by-minute energy expenditure was simultaneously measured by the index measures and portable indirect calorimeter as participants were instructed to perform a sequence of lifestyle type activities adapted and modified from a standardized field test of functional status previously used in chronic lung disease patients,33 which included four activities: walking on flat, walking on incline (2 to 5% grade), rising from a chair and sitting in a second chair spaced 1 m apart (sit-to-stand), and moving a 1 kg weight between 3 heights (weight moved from a level at shoulder height, to a level at waist height, to the floor, back to waist level and back to shoulder level) (lift-bend). Following the lifestyle activities, participants performed submaximal steady state cycling activities at 10, 25, 50 and 60% of peak workload. Each activity was performed for 2 minutes with individually determined rest breaks between activities (until heart rate returned to within 10 beats/min of resting value). The start and end times of each activity were synchronized by timestamps on all three index measures and the portable indirect calorimeter. Energy expenditure outputs from the index measures were converted to standard units of kcal/min. Energy expenditure was calculated from portable indirect calorimetry as previously described.34 Energy expenditure was averaged over the last minute of each 2-minute activity from the index measures and portable indirect calorimeter.
A Randomized, Double-Blind, Crossover Study to Determine the Available Energy from Soluble Fiber
Published in Journal of the American College of Nutrition, 2021
Kirstie Canene-Adams, Lisa Spence, Lore W. Kolberg, Kavita Karnik, DeAnn Liska, Eunice Mah
Non-digestible carbohydrates are fermented to varying degrees by intestinal microbes and metabolized into short chain fatty acids (SCFA), gasses (e.g., carbon dioxide, hydrogen, methane), and bacterial cell components. SCFA are absorbed from the large intestine and provide energy to the host (1). Thus, the amount of available energy from non-digestible and fermentable carbohydrates is dependent upon the amount of SCFA produced. The energy values for fermentable fibers are important for reformulation and nutrition labeling purposes. The available energy from fibers in humans may be estimated using indirect calorimetry (2) or breath hydrogen excretion (3–6). Indirect calorimetry studies are time-consuming, expensive, and stressful for subjects and thus, are not commonly done. In contrast, breath hydrogen excretion studies are simple, noninvasive, and have been used for estimating the available energy of various non-digestible carbohydrates (3–6).