Which of the following is a major limitation of indirect calorimetry?

Asked By: Aya Blankenburg | Last Updated: 28th June, 2020
Category: science chemistry
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Limitations of indirect calorimetry
Practical difficulties: Urinary nitrogen, which is required for the Weir equation, requires a 24-hour urinary collection. The metabolic cart is expensive and cumbersome to implement. The use of this device requires special training.

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Correspondingly, what is indirect calorimetry used for?

Indirect calorimetry (a type of whole body calorimetry where all gas consumption and gas exhalation are continuously monitored) can be used to determine energy expenditure through the use of equations relating total O2 consumption, CO2 expiration, and urinary nitrogen excretion to energy utilization.

One may also ask, what is indirect calorimetry quizlet? a technique of measuring heat energy in which an organism is placed in a calorimeter chamber, as the organism gives off heat it is transferred to the surrounding water jacket in the walls of the chamber. this change in temp = energy released. (most accurate, but expensive) indirect calorimetry.

Also to know, which of the following limitations are most likely to impact the accuracy of indirect calorimetry measurements?

The commonly encountered pitfalls in measurement of RQ[6] include air leaks in the respiratory circuit, extreme pain or agitation during the measurement, or recent procedures that affect gas exchange (e.g., hemodialysis). Under or overfeeding can also affect RQ as can the proportion of CHO and fat in the diet.

What is direct and indirect calorimetry?

While direct calorimetry is achieved through direct measurement of total body heat produced, such as via a thermally sealed chamber, indirect calorimetry measures respiratory gases, i.e. oxygen (O2) and carbon dioxide (CO2) that are influenced by metabolism to meet energy requirements (Figure 1).

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Why is indirect calorimetry the gold standard?

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.

What is calorimetry used for?

A calorimeter is an object used for calorimetry, or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity. Differential scanning calorimeters, isothermal micro calorimeters, titration calorimeters and accelerated rate calorimeters are among the most common types.

How is direct calorimetry measured?

Direct calorimetry measures the heat production of an individual, in calories, when placed in an insulated chamber where the heat is transferred to surrounding water. This is a very accurate method of measuring energy expenditure.

What does calorimetry mean?

Calorimetry is the act of measuring the heat of chemical reactions or physical changes, or the science of making such measurements. Calorimetry is performed with a calorimeter. The word calorimetry is derived from the Latin word calor, meaning heat and the Greek word μέτρον, meaning measure.

Is indirect calorimetry expensive?


Currently, the most accurate clinical tool used to measure REE is indirect calorimetry, which is expensive, requires trained personnel, and has significant error at higher inspired oxygen concentrations.

What is your BMR?

Basal Metabolic Rate is the number of calories required to keep your body functioning at rest. BMR is also known as your body's metabolism; therefore, any increase to your metabolic weight, such as exercise, will increase your BMR. To get your BMR, simply input your height, gender, age and weight below.

What is calorimetry in nutrition?

Calorimetry. Calorimetry is a process that quantifies the heat release from metabolism of cellular fuels. It provides assessment of caloric energy present in foods and allows for measurement of energy expenditure to determine adequate calorie requirement.

What is feo2?

FEO2 = fraction of oxygen in expired air = variable. To prevent the need to measure both inspired and expired volumes, and introduce the measure of carbon dioxide, the Haldane transformation is used.

How is vco2 measured?

The equation for calculating absolute VCO2 is: VCO2 (mL/min) = (VE x FeCO2) – (VI x FiCO2). "VE" stands for the volume of air expired in mL/min, "VI" represents the volume of air inspired in mL/min, "FeCO2" stands for the fraction of CO2 in expired air and "FiCO2" stands for the fraction of CO2 in inspired air.

What is feo2 and FeCO2?


TV, Tidal Volume; VE, Ventilation; FeO2, Fractional. content of Expired Oxygen; FeCO2, Fractional content of expired CO2; VO2, Oxygen uptake; VCO2, expired CO2; RER, respiratory exchange ratio; EqO2, equivalent O2 and VE/VCO2.

What does RER mean?

respiratory exchange ratio

How is RQ calculated?

The respiratory quotient (RQ) is the ratio:
  1. RQ = CO2 eliminated / O2 consumed
  2. RQ value corresponds to a caloric value for each liter (L) of CO2 produced.
  3. RQ as measured includes a contribution from the energy produced from protein.

What is adaptive thermogenesis theory?

Adaptive thermogenesis refers to a slowing of metabolism that's greater than expected based on lean body mass. When you lose weight, you also lose muscle. It also explains why weight loss plateaus are so common.

What is open circuit spirometry?

The term “open circuitspirometry refers to the method of conducting spirometry where the subject takes a maximal inspiration from the room, inserts the mouthpiece into the mouth, and then blows out either slowly (SVC) or rapidly (FVC) until the end-of-test criterion is met.

When was the calorimeter invented?


The first ice calorimeters were built based on Joseph Black's concept of latent heat, introduced in 1761. Antoine Lavoisier coined the term calorimeter in 1780 to describe the apparatus he used to measure heat from guinea pig respiration used to melt snow.

What is the Haldane transformation?

Haldane transformation - multiplication of inspired oxygen concentration by the ratio of expired to inspired nitrogen concentration in the calculation of oxygen consumption or respiratory quotient by the open circuit method. Haldane tube - a tube for securing human alveolar air samples.

Why can co2 be used as an indirect measure of catabolism?

Why can CO2 (exhaled in expiration) be used as an indirect measure of catabolism? During any production of energy in the citric acid cycle (or during anaerobic metabolism) CO2 is produced. This, unlike the measurement of O2 for metabolism, represents the fuels that are broken down, and not the energy that is produced.