Triple Isotope Method for Energy Expenditure Analysis
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Solution Overview
Problem
The doubly labeled water (DLW) method for measuring total energy expenditure is costly due to high requirements for 18O labeling and suffers from measurement uncertainty caused by background isotope fluctuations, limiting its practicality for individual measurements.
Innovation Solution
Measuring the 17O stable isotope in body water samples to estimate background fluctuations of 2H and 18O, reducing the need for expensive 18O labeling and decreasing measurement uncertainty using optical spectroscopy instruments like Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high levels of 18O are used to label body water in the DLW method, then measurement precision of TEE is improved, but cost of the method increases significantly
Solution Approach 1:
The patent introduces 17O as an intermediary substance that mediates between the expensive 18O tracer and the measurement goal. By measuring 17O background levels, the system can estimate and correct 18O background fluctuations without requiring high doses of 18O, thus reducing cost while maintaining measurement precision
Solution Approach 2:
The patent implements a feedback mechanism where 17O measurements provide information about background isotope fluctuations, which is then used to correct the 18O and 2H tracer measurements. This feedback loop allows for accurate TEE calculation with reduced tracer doses
2Reliability
If high levels of 18O tracer are administered to distinguish from background levels, then measurement reliability is improved, but cost increases
Solution Approach 1:
17O serves as an intermediary indicator that correlates with 18O background fluctuations. By monitoring 17O levels, the system can reliably estimate 18O background without administering high doses of 18O, thereby maintaining measurement reliability while reducing cost
Solution Approach 2:
The patent uses 17O as a proxy or copy that mirrors the behavior of 18O background fluctuations. Instead of directly measuring high levels of 18O to overcome background noise, the system measures 17O which provides a correlated signal, effectively creating a cheaper substitute measurement
3Device complexity
If dietary and beverage intake variations are not accounted for, then device complexity is reduced, but measurement precision deteriorates due to background isotope fluctuations
Solution Approach 1:
The system continuously monitors 17O levels in body water samples and uses this feedback information to adjust and correct the 18O and 2H tracer measurements. This real-time correction accounts for dietary and beverage intake variations, improving individual measurement precision without significantly increasing protocol complexity
Solution Approach 2:
17O acts as an intermediary indicator that captures the effect of dietary and beverage intake on background isotope levels. By measuring this intermediary parameter, the system can correct for these variations and improve measurement precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the cost of the DLW method and improves individual measurement accuracy, potentially decreasing the 18O label cost by 75% and reducing uncertainty by five-fold, making it more suitable for individual assessments.
Implementation Method 1
measuring the 17O stable isotope in body water samples to estimate background fluctuations of 2H and 18O using optical spectroscopy instruments like Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS)
Data Source
AI summary
A method of measuring energy expenditure in a living subject comprises: (a) administering a specified dose of doubly-labeled water (2H218O) to a living subject; (b) obtaining samples at three or more times of body water from the living subject; (c) measuring 2H/1H, 17O/16O and 18O/16O ratios in each of the obtained samples using optical spectroscopy; and (d) determining (1) a combined value of flux of body water and exhaled carbon dioxide from a change in measured 18O/16O over time, (2) a value of flux of body water alone from a change in measured 2H/1H over time, and (3) a reference value of isotopic background fluctuation from a change in measured 17O/16O over time. Using 17O measurements to estimate background fluctuations of the 2H and 18O decreases the required isotope dosing of subjects or decreases uncertainty at current dosing levels.