Search Results
Found 1 results
510(k) Data Aggregation
(238 days)
The device is intended for use in clinical and research applications to measure oxygen uptake.
The REEVUE is an indirect calorimeter. The REEVUE device measures oxygen consumption (VO2) and estimates Resting Metabolic Rate (RMR) based on the measured VO2 using an assumed respiratory quotient (RQ=0.83). Resting metabolic rate can also be referred to as Resting Energy Expenditure (REE).
Measurement of energy requirements can be used for nutritional assessment. A typical application would be for counseling obese patients on their caloric intake requirements.
During a test the patient breathes through a mouthpiece with unidirectional breathing valves. These valves allow the patient to breath in ambient air and then direct the expiratory gas down a hose to the device. The flow rate of the expiratory gas is measured and the patient's tidal volume and respiratory rate is calculated. The expiratory gas passes through a mixing chamber so that the mixed expiratory oxygen concentration can be found. The oxygen concentration of the mixed expiratory gas is measured.
Oxygen consumption can be expressed as the volume of oxygen breathed in minus the volume of oxygen breathed out. This can be described as:
[VO2 - VI|IO2 - VE|E O2] (1)
where VO2 is the oxygen consumption, VI is the inspiratory volume, FIO2 is the inspiratory oxygen fraction, VE is the expiratory volume, and FEO2 is the expiratory oxygen fraction.
Since the REEVUE only measures the expiratory volume of gas breathed out, the inspired volume must be estimated. This is similar to other legally marketed medical devices. When measuring both CO2 and O2 this is often referred as the Haldane method.
To estimate the inspired volume, the components of the expiratory and inspiratory volumes need to be accounted for. In estimating the inspiratory volume the REEVUE requires an estimate of the Respiratory Quotient (Ro). The REEVUE uses an assumed RO of 0.83. The RO is defined as:
RQ = VCO2 / VO2 (2)
where VCO2 is the carbon dioxide eliminated by the patient's breathing.
An estimate of Resting Energy Expenditure (REE) is calculated using the Weir Equation with the assumed RO value of 0.83. Substituting for the VCO2 using the RO and the VO2 the Weir Equation can be expressed as:
Calories = { 3.941 VO2-STPD + 1.106 RQ VO2-STPD } x { 1 - 0.082 PF } (3)
Where
Calories .......... is the calories burned per liter of oxygen consumed. PF ......................is the fraction of total energy production due to protein oxidation.
Typical values for Pr range from 0.08 to 0.2, corresponding to 8 to 20% protein. We selected a default value of 0.125 for our calculations. In reporting (REE) in Kcal/day, this simplifies to:
RMRKcal/day = 6.925 x VO2-ml/min-STPD (4)
Here's a breakdown of the acceptance criteria and study details for the REEVUE Indirect Calorimeter, based on the provided 510(k) summary:
REEVUE Indirect Calorimeter: Acceptance Criteria and Study Details
1. Table of Acceptance Criteria and Reported Device Performance
Non-Clinical Performance Criteria (Nitrogen Injection Method):
| Test | Acceptance Criteria (Bias) | Acceptance Criteria (Precision - 1 Std Dev) | Reported Device Performance (Bias) | Reported Device Performance (Precision - 1 Std Dev) | Pass/Fail Status |
|---|---|---|---|---|---|
| VO2 Accuracy (range 50-450 ml/min) | < 3 ml/min or 1% of reading | < 5 ml/min or 2% of reading | 1.89 ml/min (0.84%) | 3.7 ml/min (1.3%) | Pass |
| VO2 accuracy (Minute Volume 3-20 L/min) | < 3 ml/min or 1% of reading | < 5 ml/min or 2% of reading | 1.89 ml/min (0.84%) | 3.7 ml/min (1.3%) | Pass |
| VO2 accuracy (FeO2 12-20%) | < 3 ml/min or 1% of reading | < 5 ml/min or 2% of reading | 1.89 ml/min (0.84%) | 3.7 ml/min (1.3%) | Pass |
| Inter-device variability (5 devices) | < 3 ml/min or 1% of reading | < 5 ml/min or 2% of reading | 1.3 ml/min (0.6%) | 3.46 ml/min (1.3%) | Pass |
| Long-term stability (10 tests over 21+ days) | < 3 ml/min or 1% of reading | < 5 ml/min or 2% of reading | 0.9 ml/min (0.3%) | 3 ml/min (0.9%) | Pass |
Clinical Performance Criteria (Douglas Bag Comparison):
While explicit numerical acceptance criteria for the clinical study (Douglas Bag comparison) are not stated in the same manner as the non-clinical tests, the "Discussion" section of the clinical data acts as an implied acceptance criterion by stating "very good agreement between the REE-VUE and the Douglas Bag method."
| Performance Metric | Reported Device Performance (REEVUE vs. Douglas Bag) |
|---|---|
| Average difference | -3.22% (-7.6 ml/min) |
| Standard deviation of error | 3.4% (6.7 ml/min) |
| Correlation coefficient ($R^2$) | 0.997 |
| Slope factor of regression line | 1.0081 |
2. Sample Size and Data Provenance
Non-Clinical Test Set:
- Sample Size: The "VO2 accuracy" tests (over range, minute volume, FeO2) were conducted under 26 separate conditions. The "Inter-device variability" test used 2 standard conditions across 5 units (10 data points). The "Long Term Stability" test involved 10 separate tests.
- Data Provenance: This was a retrospective, lab-based (bench-top) study using a motorized patient ventilator and gas flow analyzer to simulate breathing. The origin of the data is implied to be internal testing at KORR Medical Technologies, Inc.
Clinical Test Set:
- Sample Size: 13 comparisons were made using 8 subjects.
- Data Provenance: Prospective clinical study conducted at the University of Utah.
3. Number of Experts and Qualifications for Ground Truth (Test Set)
- Non-Clinical Test Set: No human experts were used to establish ground truth. The ground truth was established by precise laboratory measurements using a gas flow analyzer (VT Plus, BioTek Instruments, Winooski Vermont) to control the flow of pure nitrogen, thereby exactly controlling and knowing the amount of oxygen consumed.
- Clinical Test Set: No specific number of experts or their qualifications are mentioned for establishing the ground truth. The Douglas Bag method itself is considered the "gold standard" for oxygen consumption measurement. The analysis of the Douglas bag contents (volume, O2, and CO2 concentrations) would typically be performed by trained lab personnel, but no expert review (e.g., radiologist) is relevant for this type of physiological measurement.
4. Adjudication Method (Test Set)
- Non-Clinical Test Set: Not applicable. Ground truth was established by precise experimental control and measurement, not by expert review requiring adjudication.
- Clinical Test Set: Not applicable. The Douglas Bag method is a direct measurement method, not requiring expert judgment to establish ground truth or an adjudication process for subjective assessments.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No MRMC comparative effectiveness study was mentioned. The study compares the device's measurements against a gold standard (Douglas Bag) and simulated values, not against human readers. Therefore, an effect size of human readers improving with/without AI assistance is not applicable.
6. Standalone Performance Study
Yes, a standalone (algorithm only) performance study was done for both non-clinical and clinical evaluations.
- Non-Clinical Study: The REEVUE device's measured $V_{O2}$ values were compared directly against known simulated $V_{O2}$ values established by the nitrogen injection method.
- Clinical Study: The REEVUE device's measured $V_{O2}$ values were compared directly against $V_{O2}$ values obtained using the Douglas Bag method (considered the gold standard).
7. Type of Ground Truth Used
- Non-Clinical Test Set: The ground truth was established by precisely controlled simulated conditions and direct physical measurements of gases using calibrated laboratory equipment (nitrogen injection method, gas flow analyzer).
- Clinical Test Set: The ground truth was established using the Douglas Bag method, which is considered the "gold standard" for measuring oxygen consumption. This involves direct collection and analysis of expired gases.
8. Sample Size for the Training Set
The document does not mention a training set or a training process for the REEVUE device. This device is described as an indirect calorimeter that measures physical parameters ($V_{O2}$) and estimates Resting Metabolic Rate (RMR) based on established physiological equations (Weir Equation) and assumed constants (RQ=0.83). It does not appear to be an AI/machine learning device that requires a training set in the conventional sense.
9. How Ground Truth for the Training Set Was Established
Since no training set is mentioned for an AI/machine learning model, this question is not applicable. The device's operation is based on physical principles and equations, not on learning from a dataset.
Ask a specific question about this device
Page 1 of 1