(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.
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K021490 510(k) Summary
In accordance with the Safe Medical Devices Act of 1990 (SMDA), this is a summary of the safety and effectiveness information for this premarket notification upon which an equivalence determination could be based (510(k) summary) [21 CFR § 807.92(c)].
1. Applicant Information
| Applicant: | KORR Medical Technologies, Inc. |
|---|---|
| Contact: | Scott A. Kofoed |
| Address: | 3090 East 3300 South Suite 100Salt Lake City, UT 84109 |
| Phone: | (801) 483-2080 |
|---|---|
| Fax: | (801) 483-2123 |
| Date Summary Prepared: | October 1, 2002 |
2. Device Name and Classification
| Trade name: | REEVUE Indirect CalorimeterModel: 8100 |
|---|---|
| Common Name: | Indirect Calorimeter |
| Classification name: | Computer, Oxygen-Uptake |
| Classification Code | CFR Section: 21 CFR ξ 868.1730 |
| Product Code: | AN-BZL |
| Panel: | Anesthesiology |
| Class: | 2 |
3. Identification of Legally Marketed Predicate Device
Device: ........................................BodyGem (also marketed as MedGem) Marketing Company: ......................Healthetech Inc. 510(k) Number:....................................K010577
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Contents of Summary:
| 1. Applicant Information |
|---|
| 2. Device Name and Classification |
| 3. Identification of Legally Marketed Predicate Device |
| 4. Description of the Device |
| 5. Intended Use / Indications for Use |
| 5.1 Typical Applications Where the Device may be Used |
| 6. Technological Characteristics Compared to Predicate Device |
| 6.1 Comparison Table to Predicate Device |
| 7. Non-clinical Performance Data to Establish Equivalence |
| 8. Clinical Performance Data to Establish Equivalence |
| 9. Substantial Equivalence Conclusion |
| 9.1 Does the new device have same indication statements? |
| materials? |
| 9.3 Are the descriptive characteristics precise enough to ensure equivalence? 18 |
| 9.4 Are performance data available to assess equivalence? |
| 9.5 Does performance data demonstrate equivalence? |
| 9.6 Substantially Equivalent Determination: |
4. Description of the Device
The REEVUE is an indirect calorimeter. The REEVUE device measures oxygen consumption ($V_{O2}$) and estimates Resting Metabolic Rate (RMR) based on the measured $V_{O2}$ 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:
$$\left[\left.V_{O2} - \left.V_{I}\right|{IO2} - \left.V{E}\right|_{E\ O2}\right] \tag{1}$$
where $V_{O2}$ is the oxygen consumption, $V_I$ is the inspiratory volume, $F_{IO2}$ is the inspiratory oxygen fraction, $V_E$ is the expiratory volume, and $F_{EO2}$ is the expiratory oxygen fraction.
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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 $R_O$ of 0.83. The $R_O$ is defined as:
$$R_Q = \frac{V_{CO_2}}{V_{O_2}}\tag{2}$$
where $V_{CO2}$ 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 $R_O$ value of 0.83. Substituting for the $V_{CO2}$ using the $R_O$ and the $V_{O2}$ the Weir Equation can be expressed as:
$$\text{Calories} = \left{ 3.941 , V_{O2-STPD} + 1.106 R_Q , V_{O2-STPD} \right} \times \left{ 1 - 0.082 , P_F \right} \tag{3}$$
Where
Calories .......... is the calories burned per liter of oxygen consumed. $P_F$ ......................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:
$$RMR_{\text{Kcal/day}} = \quad 6.925 \times V_{O2-ml/\text{min}-STPD} \tag{4}$$
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Image /page/3/Picture/0 description: The image shows a MetaCheck metabolic rate analyzer. The device is light gray with a darker gray control panel. A clear, corrugated tube is connected to the left side of the device and extends to a T-shaped connector.
Figure 1 Picture of Prototype of Device. The product name on the prototype was "MetaCheck".
Image /page/3/Picture/2 description: In the image, a woman is sitting in a chair with a tube in her mouth, while another woman stands next to a machine. The woman in the chair is wearing a dark shirt and has a white cloth draped over her lap. The tube in her mouth is connected to the machine, which is on a cart. The other woman is wearing a light-colored shirt and jeans and appears to be operating the machine. The image is labeled as "Figure 2 Example of a test with the Device."
Figure 2 Example of a test with the Device
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5. Intended Use / Indications for Use
The device is intended for use in clinical and research applications to measure oxygen uptake.
5.1 Typical Applications Where the Device may be Used
The device could be used in applications where oxygen consumption or measurements of indirect calorimetery would typically be used. This could include:
- Diseases where patients may be at risk for malnutrition .
- Burn Patients .
- Weight Management .
- Parenterally Fed Patients .
- Enterally Fed Patients ●
- Inflammatory States: Sepsis .
Since the device does not measure carbon dioxide, and hence respiratory quotient, it could not be used in applications that require a measure of the respiratory quotient. Since the device assumes the patient is breathing ambient air, it is not intended for patients where supplementary oxygen is being given.
6. Technological Characteristics Compared to Predicate Device
Both the device and the predicate device measure oxygen consumption and then estimate resting metabolic rate using the Weir Equation and an assumed respiratory quotient (Rg). Both devices measure gas flow, oxygen concentration, barometric pressure, temperature, and relative humidity. Both devices use a single-use mask or mouthpiece.
The main difference between the current device (REEVUE) and the predicate device (BodyGem) is that the predicate device is a handheld device that measures oxygen concentration and gas flow near the patient's mouth. The current device (REEVUE) is a "bench top" unit that uses a traditional mixing chamber approach, which allows the expiratory gas to mix. Since the gas is mixed, the oxygen sensor does not need to have a high frequency response since it is continuously measuring the mixed expiratory oxygen concentration.
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6.1 Comparison Table to Predicate Device
| Parameter | REEVUE(Current Device) | BodyGem(Predicate Device) | ComparisonNotes |
|---|---|---|---|
| Indications for Use | For use in clinical and researchapplications to measureoxygen uptake | For use in clinical and researchapplications to measureoxygen uptake | Intended use statements aresimilar. Both products areintended for oxygenconsumption and indirectcalorimetery measurements. |
| Target Population | Weight > 33 kg (73 pounds)Pediatric to Adult PatientsDevice is not compatible withmechanical ventilation orpatients on supplementaloxygen.Specified for breath rates of 5to 40 breaths per minute andfor tidal volumes ranging from200 ml to 3000 ml. | Device is not compatible withmechanical ventilation orpatients on supplementaloxygen.Specified for breath rates of 5to 25 breaths per minute andfor tidal volumes ranging from500 ml to 1500 ml. | The minimum tidal volume ofthe predicate device is 500 ml.This is a typical tidal volumefor an adult male. |
| Sterility | All patient contact elementsare single-patient use. Theseaccessories are considered asclean, non-sterile. | The patient holds the reusabledevice in his/her hand.A filter is placed in the deviceto prevent cross-contaminationof the gas breathed by thepatient. | Neither device uses sterilecomponents. Both devices useclean, non-sterile singlepatient use components. |
| Biocompatibility | All patient contact componentsare legally marketed medicaldevices used as defined bytheir intended use statements. | No known issues. | Same. |
| Mechanical Safety | No mechanical safety risksidentified. | No mechanical safety risksidentified. | Same. |
| Chemical Safety | No chemical safety risksidentified. | No Known Issues. | Same. |
| Anatomical Sites | Measures the respiratory gasesat the patient's mouth andnose. | Measures the respiratory gasesat the patient's mouth andnose. | Same. |
| Human Factors | Requires patient to keepmouthpiece/mask sealed aboutmouth/nose. | Requires patient to keepmouthpiece/mask sealed aboutmouth/nose. | Same. |
| Energy Used | External 12-volt power supplyfrom device. | External 12-volt power supplyfrom device. | Same. |
| Energy Delivered | No energy delivered to patient. | No energy delivered to patient. | Same. |
| Compatibility withEnvironment | No known issues. | No known issues. | Same. |
| Compatibility with OtherDevices. | No known devices forcompatibility issues. | No known devices forcompatibility issues. | Same. |
| Where used | Doctor's office. Hospitalnutritional assessment. | Doctor's office. Hospitalnutritional assessment. | Same. |
| Parameter | REEVUE(Current Device) | BodyGem(Predicate Device) | ComparisonNotes |
| Standards: Electrical Safety | EN60601-1 (1996)UL2601-1 (2nd edition)CSA C22.2 NO 601.1-M90Class 1, Type BF applied partDrip proof equipment (IPX1) | EN60601-1 (1996)UL2601-1CSA601-1Class II, Type B | Similar safety.The Class 2 on the predicatedevice is due to the plasticenclosure.The Class 1 on the current(REEVUE) device is due tothe grounded metal enclosure. |
| Standards: EMC Testing | EN60601-1-2 | EN60601-1-2 | Same. |
| Standards: Voluntary | No applicable voluntarystandards. | No applicable voluntarystandards. | Same. |
| Thermal Safety | No known thermal safetyissues. | No known thermal safetyissues. | Same. |
| Radiation Safety | No known radiation safetyissues. | No known radiation safetyissues. | Same. |
| Design - General | Device measures expiratoryflow and oxygenconcentration. Inspiratoryvolume is estimated. Ambient(inspired) oxygenconcentration is assumed20.93.Device is a desktop unit thatconnects to the patient via 1.5meters of breathing circuithose and a single-patient usemouthpiece.The display shows the RestingMetabolic Rate and VO2. | Ambient (inspired) oxygenconcentration is assumed20.93 for device calibration.Inspiratory and expiratoryflow and oxygenmeasurements are integrated toobtain VO2.The device is handheld.The display shows the RestingMetabolic Rate and VO2. | The predicate device, theBodyGem, measures VO2 on abreath-by-breath basis whereasthe current device uses amixing chamber design. Themixing chamber is comparableto other legally marketeddevices indicated in this510(k) notification. |
| Specification Comparison | |||
| Barometric Pressure Sensor | |||
| Accuracy | $\pm$ 5 mmHg | $\pm$ 4 mmHg | Not a significant Difference |
| Resolution | 1 mmHg | 0.05 mmHg | Not a significant Difference |
| Min/Max Range | 500 to 800 mmHg | 515 to 795 mmHg | Not a significant Difference |
| Temperature Sensor | |||
| Accuracy | $\pm$ 1 °C | $\pm$ 1 °C | Not a significant Difference |
| Resolution | 0.1 °C | 0.01 °C | Not a significant Difference |
| Min/Max Range | 10 to 40 °C | 5 to 50 °C | Not a significant Difference |
| Humidity Sensor | |||
| Accuracy | $\pm$ 10 %RH | $\pm$ 10 %RH | Not a significant Difference |
| Resolution | 1 %RH | 1 %RH | Not a significant Difference |
| Min/Max Range | 10 to 95 %RH | 10 to 98 %RH | Not a significant Difference |
| Oxygen Sensor | |||
| Type | Galvanic Fuel Cell | Florescent Quenching | |
| Accuracy | $\pm$ 0.2 %O2 | $\pm$ 0.4 to 0.8 %O2 | |
| Resolution | 0.01 %O2 | 0.03 %O2 | Not a significant Difference |
| Min/Max Range | 0 to 30 %O2 | 10 to 21 %O2 | Not a significant Difference |
| Parameter | REEVUE(Current Device) | BodyGem(Predicate Device) | ComparisonNotes |
| Nominal Sensor Life | > 30 months | Not reported. However, theuser manual does describe thatan error message will be givenwhen the sensor needs to bereplaced. | The REEVUE notifies the userwhen the oxygen sensor isnearly depleted. When thesenor is depleted device willlockout user operation. |
| Flow Sensor | |||
| Type | Fixed-orifice DifferentialPressure Pneumotach | Ultrasonic time-of-flight | Flow technology is different,but should not be significant ifeach works within thepublished specifications.The REEVUE flow sensor isalso used in other legallymarketed medical devices formeasuring expiratoryrespiratory gas flow. |
| Accuracy | ± 2% of reading | ±1% | Not a significant differencesince the REEVUE estimatesthe inspired volume from theexpired volume. (i.e. similarto traditional HaldaneEquation) If both theexpiratory and inspiratoryvolumes are measured, ahigher flow sensor accuracy isrequired. |
| Resolution | 10 ml / sec(0.01 LPM) | 1 ml / sec | Not a significant Difference |
| Min/Max Range | - 40 to 150 LPM(-600 to 2500 ml / sec) | 0 to 2100 ml / sec | Not a significant Difference |
| Respiratory Tidal Volume Measurements | |||
| Breathing Rate | 5 to 40 breaths/min | 5 to 25 breaths/min | Not a significant Difference |
| Tidal Volume | 200 to 3000 ml | 500 to 1500 ml | Not a significant Difference |
| VO2 Measurements | |||
| Range | < 70 to > 720 ml /min 02 | 72 to 721 ml /min 02 | Not a significant Difference |
| Resolution | 1 ml/min 02 | 1 ml/min 02 | Same. |
| RMR Measurements | |||
| Calculation Method | Weir Equation with assumedRQ = 0.83 | Weir Equation with assumedRQ = 0.85 | Not a significant Difference. |
| Range | 500 to > 5,000 kcal/day | 500 to 5,000 kcal/day | Same. |
| Resolution | 7 kcal/day | 10 kcal/day | Not a significant Difference. |
| Measurement Time | 10 minutes | 10 min max | Not a significant Difference. |
| Size & Weight | |||
| Size | 20 x 30 x 10 cm | 5.5 x 5.5 x 11.5 cm | REEVUE is a desktop unit.The predicate device is ahandheld device. |
| Weight | 5.75 lbs. (2.6 kg) | 4 oz. | REEVUE is a desktop unit.The predicate device is ahandheld device. |
| Disposables | |||
| Parameter | REEVUE(Current Device) | BodyGem(Predicate Device) | ComparisonNotes |
| Mask Sizes | N/A | Small, medium, large | REEVUE does not have amask. |
| Mouthpiece | One size | One size | Same. |
| Filter Efficiency | Bacterial Filtration 99.999+%Viral Filtration 99.99+% | Better than 99% of particles at2 microns at flow rates up to30 liters per minute | Due to the uni-directional gasflow in the REEVUE, a filteris only recommended, but notrequired by the REEVUE. |
| Operating Environment | |||
| Temperature Range | 15 to 30 °C(59 to 86 °F) | 15 to 30 °C(59 to 86 °F) | Same. |
| Elevation Range | -30 to 3040 meters(-100 to 10,000 feet) | -30 to 3040 meters(-100 to 10,000 feet) | Same. |
| Barometric Pressure Range | 525 to 780 mmHg | 525 to 780 mmHg | Same. |
| Relative Humidity Range | 10 to 95% RHnon-condensing | 10 to 88% RHnon-condensing | Not a significant Difference |
| Storage Environment | |||
| Temperature Range | -20 to 60 °C(-4 to 140 °F) | -20 to 60 °C(-4 to 140 °F) | Same. |
| Barometric Pressure Range | 375 to 800 mmHg | 140 to 780 mmHg | Not a significant Difference. |
| Relative Humidity Range | 10 to 95% RHnon-condensing | 0 to 100% RHnon-condensing | Not a significant Difference. |
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7. Non-clinical Performance Data to Establish Equivalence
General performance testing for hardware and software is presented in the body of the 510(k) notification. The non-clinical bench test that establishes equivalence is summarized here.
The accuracy of the REEVUE device was analyzed using the nitrogen injection method. In this method, a motorized piston or other device simulates patient breathing. A precisely measured flow of pure nitrogen (N2) is added to the gas that is pumped into the device under test (REEVUE). Injecting nitrogen simulates expired air, which has a lower concentration of oxygen than fresh air. By exactly measuring and controlling the flow of nitrogen, the amount of oxygen consumed can be exactly controlled and known.
Methods and Materials - A motorized patient ventilator (Harvard model 608, Harvard Apparatus, South Natick, MA) is used to draw in room air and pump it into the device under test. The ventilator can be adjusted to simulate various flow rates and minute volume levels. The nitrogen flow is adjusted using a needle valve. The exact flow of N2 is measured using a gas flow analyzer (VT Plus, BioTek Instruments, Winooski Vermont).
Test Range - VO2 accuracy was tested over minute volume levels between 3 and 20 liters per minute. Simulated VO2 levels for these respiration levels were selected such that tests were taken using expired oxygen fractions between 12 and 20 percent.
Pass/Fail Criteria
Bias: (Average error) should be less than 3 ml/min or 1% of reading Precision (1 standard deviation): Less than 5 ml/min or 2% of reading for all tests.
Results - For each measurement the $VO_2$ measured by the REE-VUE and the simulated VO2 was recorded. The percent difference was calculated as:
The device was tested under 26 separate conditions with an average simulated $VO_2$ of 231.3 ml/min. The average of the percent difference across all measurements was 0.84% (1.89 ml/min). The standard deviation of the error was 1.3% (3.70 ml/min). The Plot below shows the measured value plotted against the actual values. Regression analysis shows the correlation between the actual and measured values was $r^2$ = 0.9992 and the factor (slope) relating the two values was 1.0088.
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Image /page/10/Figure/0 description: The image is a scatter plot titled "Measured vs. Actual VO2". The x-axis is labeled "Simulated VO2 (ml/min)" and ranges from 0 to 500. The y-axis is labeled "REE-VUE VO2 (ml/min)" and ranges from 0 to 500. A line of best fit is plotted on the scatter plot, with the equation y = 1.0088x - 0.112 and an R-squared value of 0.9992.
Figure 3 - Regression Plot of Nitrogen Dilution Test
The plot below shows the percent difference of the measurements vs. the minute volume. Note that the percent difference is similarly low regardless of the simulated minute volume (minute volume is amount of air breathed in one minute).
Image /page/10/Figure/3 description: This image is a scatter plot titled "% Difference vs Minute Volume". The x-axis is labeled "Minute Volume (L/min)" and ranges from 0 to 25. The y-axis is labeled "Percent Difference" and ranges from -10 to 10. The average error is 1.89 ml/min (0.84%).
Figure 4 - Independence on ventilation demonstrated from nitrogen dilution tests.
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The next plot shows the percent difference plotted against the concentration of oxygen in the expired air. Note that the error is consistently low even at the extremes of oxygen concentration.
Image /page/11/Figure/1 description: The image is a scatter plot titled "Percent Difference vs Expired Percent Oxygen". The x-axis is labeled "Percent Expired Oxygen" and ranges from 10 to 20. The y-axis is labeled "Percent Difference" and ranges from -10 to 10. The plot shows data points scattered around the zero line, with an average error of 1.89 ml/min (0.84%).
Figure 5 - Independence on expiratory oxygen concentration demonstrated from nitrogen dilution tests.
Inter-device Variability - We also tested a set of five REE-VUE systems to assess the variability of the results between systems. In this test, the No dilution technique was set up using two standard oxygen consumption and minute volume conditions. The table below shows the measured results:
| Unit # | Simulated VO2 | Measured VO2 | error | % error |
|---|---|---|---|---|
| 1 | 200 | 198 | -2.0 | -1.0% |
| 2 | 206 | 201 | -5.0 | -2.4% |
| 3 | 211 | 214 | 3.0 | 1.4% |
| 4 | 196 | 192 | -4.0 | -2.0% |
| 5 | 206 | 203 | -3.0 | -1.5% |
| 1 | 369 | 368 | -1.0 | -0.3% |
| 2 | 377 | 382 | 5.0 | 1.3% |
| 3 | 375 | 375 | 0.0 | 0.0% |
| 4 | 370 | 364 | -6.0 | -1.6% |
| 5 | 372 | 372 | 0.0 | 0.0% |
Note: values are in ml/min
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The average error across all units was 0.6% (1.3 ml/minute) with a standard deviation of the error of 1.3% (3.46 ml/min). There is no significant difference between measurements made with different REE-VUE systems.
Long Term Stability - We also tested the REE-VUE to assess the stability of the measurements over multiple days. Simulated oxygen uptake rates were simulated at approximately the same in 10 separate tests distributed over a 22-day period. Simulations were done using the nitrogen dilution technique as discussed above. The table below lists the date of each test along with the simulated and measured oxygen consumption values.
| Date | Simulated VO2 (ml/min) | Measured VO2 (ml/min) | Error (ml/min) | Percent Error |
|---|---|---|---|---|
| 22-Apr | 352 | 347 | -5 | -1.4% |
| 24-Apr | 326 | 326 | 0 | 0.0% |
| 26-Apr | 318 | 315 | -3 | -0.9% |
| 30-Apr | 336 | 337 | 1 | 0.3% |
| 2-May | 318 | 321 | 3 | 0.9% |
| 6-May | 323 | 327 | 4 | 1.2% |
| 8-May | 323 | 327 | 4 | 1.2% |
| 9-May | 342 | 344 | 2 | 0.6% |
| 10-May | 320 | 320 | 0 | 0.0% |
| 14-May | 339 | 342 | 3 | 0.9% |
The average error was 0.9 ml/min (0.3%) with a standard deviation of the error of 3 ml/min (0.9%). Over the entire period of the tests, the worst-case error was 1.4% of reading.
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Discussion on Performance Testing -
The pass fail criteria for nitrogen dilution testing is:
- Bias: (Average error) should be less than 3 ml/min or 1% of reading .
- Precision (1 standard deviation): Less than 5 ml/min or 2% of reading for all . tests.
| Test | Results | Pass/Fail Status |
|---|---|---|
| VO2 Accuracy over a range of 50to 450 ml/minute | Bias = 1.89 ml/min (0.84%)Std. Dev. = 3.7 ml/min (1.3%) | Pass |
| VO2 accuracy over range ofMinute volume from 3 to 20L/min | Bias = 1.89 ml/min (0.84%)Std. Dev. = 3.7 ml/min (1.3%) | Pass |
| VO2 accuracy over range ofFeO2 (mixed expired O2)from 12% O2 to 20% O2 | Bias = 1.89 ml/min (0.84%)Std. Dev. = 3.7 ml/min (1.3%) | Pass |
| Inter-device variability over 5REE-VUE devices | Bias = 1.3 ml/min (0.6%)Std. Dev. = 3.46 ml/min (1.3%) | Pass |
| Long-term stability, Device testedon 10 separate occasions over aperiod of at least 21 days | Bias = 0.9 ml/min (0.3%)Std. Dev. = 3 ml/min (0.9%) | Pass |
These results indicate that the REE-VUE meets or exceeds the pre-determined pass criteria for each test.
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8. Clinical Performance Data to Establish Equivalence
Introduction - The "Douglas bae" is considered a "gold standard" method of validating the accuracy of oxygen consumption measurement devices. The Douglas Bag method uses a large, non-porous bag to collect all of the gas expired by the individual being tested. After the gas is collected, the volume, and the concentration of oxygen and carbon dioxide of the gas collected in the bag are analyzed. This analysis gives the total volume of oxygen in the bag. Based on the bag contents and amount of time over which the bag was filled, the rate at which oxygen was consumed can be calculated.
Methods - Tests were conducted using a protocol approved by the University of Utah Institutional Review Board (IRB). Each subject provided informed consent.
For each test, the REEVUE system was calibrated using the standard automatic calibration before each test. Following auto-calibration, subjects breathed through a standard disposable mouthpiece and hose connected to the REEVUE system. Breathing was allowed to stabilize for at least 1 minute before data collection began.
After stabilization, expired gas exiting the REE-VUE was collected in a 100 Liter Douglas Bag (Hans Rudolph P/N 112377. Hans Rudolph inc. Kansas City, MO). Oxygen consumption (VO2) for each breath along with the breath rate measured by the REEVUE were stored digitally for each breath during the test. Expired gas was collected for at least 2 minutes and at least 20 Liters of gas was collected for each test. After the gas was collected, the bag was sealed. Average oxygen consumption for all of the breaths measured during the data collection period was calculated. The total time of data collection was recorded as well.
The volume and contents of the Douglas bag were analyzed following each individual's data collection. The volume of oxygen inspired by the subject was calculated using the measured ambient relative humidity and temperature. Further compensation was made to account for the difference in the rate of oxygen consumption to carbon dioxide production (respiratory quotient or RQ). The oxygen consumed during the test is the difference between oxygen consumed by the subject and the volume of oxygen that was collected in the bag. The total oxygen consumed divided by the collection time gives the rate of oxygen consumption measured by the Douglas Bag method. This rate of oxygen consumption can then be compared to the average oxygen consumption rate measured simultaneously by the REEVUE.
Results - Thirteen comparisons were made using 8 subjects. Tests were repeated in some subjects at various levels of physical activity to produce a wider range of test conditions. Measured oxygen uptake rates ranged from 138 to 545 ml/min. The average difference between the REE-VUE and the Douglas bag method was -3.22% (-7.6 ml/min). The standard deviation of the error was 3.4% (6.7 ml/min). The data plot below shows the relationship between Oxygen consumption using the Douglas bag and the REE-VUE.
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The line relating REE-VUE oxygen consumption measurements to the corresponding Douglas bag values has a slope of 1.0081 with an offset of -10 ml/min. The correlation coefficient between the two methods was $R^2$ = 0.99.
Image /page/15/Figure/1 description: This image is a scatter plot that shows the relationship between oxygen consumption measured by REE-VUE and oxygen consumption measured by the Douglas Bag method. The x-axis represents oxygen consumption measured by the Douglas Bag method in ml/min, while the y-axis represents oxygen consumption measured by REE-VUE in ml/min. The data points appear to follow a linear trend, and the equation of the line of best fit is y = 1.0081x - 10.029, with an R-squared value of 0.99.
Oxygen Consumption Accuracy, MetaCheck vs. Douglas Bag
Figure 6 - Regression Plot of Clinical Data using Douglas bag
The minimum respiratory quotient (RQ) values observed during test was 0.76, the maximum value was 1.05, and the average value was 0.93.
Discussion - This data shows very good agreement between the REE-VUE and the Douglas Bag method. Linear regression shows a good correlation between REE-VUE and Douglas bag measurements of $R^2$ = 0.997 and a slope factor of 1.0081. The range of respiratory quotients (RQ) was quite wide (0.76 to 1.05).
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9. Substantial Equivalence Conclusion
This section 9 provides a decision tree was used to determine if the current device (REEVUE) is substantially equivalent to the predicate device (BodyGem).
9.1 Does the new device have same indication statements?
Yes. The new device and the predicate device are intended for use in clinical and research applications to measure oxygen uptake. Both devices report oxygen consumption and resting metabolic rate.
9.2 Does the new device have same technological characteristics in design and materials?
Yes. Both the current device (REEVUE) and the predicate device (BodyGem) measure oxygen consumption and estimate caloric expenditure (metabolic rate). Both devices use an assumed respiratory quotient for estimate of caloric expenditure (metabolic rate).
The key technological characteristics that can affect product safety and efficacy are:
- Flow Measurement Technology .
- . Oxygen Measurement Technology
- Integration of Flow and Oxygen measurements to obtain $V_{O2}$ estimate. .
- Estimation of metabolic rate from the $V_{O2}$ using an assumed respiratory quotient. ●
| Technological Characteristic | Current Device (REEVUE) | Predicate Device (BodyGem) |
|---|---|---|
| Flow Measurement Technology | Fixed-orifice pneumotach design | Ultrasonic time-of-flight flowmeasurement |
| Oxygen Measurement Technology | Galvanic Fuel Cell | Illuminescent Quenching |
| Integration of Flow and Oxygenmeasurements to obtain VO2estimate | The expiratory gases are mixed in amixing chamber. The mixedexpiratory oxygen concentration ismultiplied by the measured volume toobtain VO2. | Flow and oxygen is measureddirectly at the patient's mouth. Thetwo instantaneous signals aremultiplied together to perform theintegration. |
The current device (REEVUE) and the predicate device (BodyGem) vary in the implementation of the first three items. The differences are summarized as follows:
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To more fully demonstrate substantial equivalence, we have included the following reference to other legally marketed devices that share the same technological characteristics.
| Technological Characteristic | Predicate Devicewith same Technological Characteristic |
|---|---|
| Flow Measurement Technology. Fixed-orificepneumotach flow sensor to measure respiratoryvolumes. | MFG: Novametrix Medical SystemsTradename: CO2SMO PLUS510(k) Number: K963380Product Code: BZCNOTE: Current Device uses same flow measurementtechnology. |
| Oxygen Measurement Technology. Galvanicoxygen sensor. | MFG: AeroSportTradename: TEEN 1000510(k) Number: K945213Product Code: BZC |
| Integration of Flow and Oxygen measurements toobtain VO2 estimate. Mixing chamber to obtain amixed expiratory oxygen concentration. | MFG: PARVO MEDICS, INC,Tradename: MMS-2400 (TRUEMAX 2400)510(k) Number: K941843Product Code: BZC |
| Estimate caloric expenditure (metabolic rate)from VO2 and assume a respiratory quotient of0.85. | MFG: HealtheTechTradename: BodyGem / MedGem510(k) Number: K010577Product Code: BZL |
9.3 Are the descriptive characteristics precise enough to ensure equivalence? No. Since the devices consist of measurement technologies that may differ slightly in the individual implementation, performance data is also required.
9.4 Are performance data available to assess equivalence? Yes. A summary of the performance data is given in section 7 and 8.
9.4.1 Predicate Device Performance Data
The predicate device advertising literature shows the accuracy for testing versus a Douglas bag. The following is a plot of the predicate device data:
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Clinical Validation Study Compares MedGem to the Classic Douglas Bag
A study completed at Appalachian State University demonstrated that the resting metabolic rates of 63 men and women, of diverse ages and sizes, were measured accurately and reliably by the MedGem. The study was presented at the North American Society for the Study of Obesity and has been submitted for publication. A scatter plot demonstrating the high level of agreement between the MedGem and the reference system is shown below.
Image /page/18/Figure/2 description: This image is a scatter plot titled "MedGem VO2 Versus Douglas Bag VO2". The x-axis is labeled "MedGem VO2 (ml/min)" and ranges from 0 to 500. The y-axis is labeled "Douglas Bag VO2 (ml/min)" and ranges from 0 to 500. The plot shows a positive correlation between the two variables, with a line of best fit drawn through the data. The MedGem Mean is 238±42, the Douglas Bag Mean is 240±43, and r = 0.81.
Summary of Comparison Data Range of VO2 Values: MedGem: 138.9 ml/min to 391.4 ml/min. Douglas Bag (gold standard of reference method): 130.0 ml/min to 360 ml/min. Key Statistics: n = 252, r = 0.81, $r^2$ = 0.65, slope = 0.83, intercept = 41.0, standard error of estimate = 27.1 ml/min.
Figure 7 - Predicate Device (BODYGEM) Published Accuracy. Scanned Image from predicate device product literature.
The regression analysis statistics reported show that:
- n = 252 tests .
- $r^2$ = 0.65 ●
- Slope of regression Line = 0.83 ●
- Intercept of Regression Line = 41.0 $V_{O2}$ (ml/min) .
- The standard error of the estimate was 27.1 ml/min .
- Mean value was 238 ± 42 ml/min .
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9.5 Does performance data demonstrate equivalence?
Yes. The performance data demonstrates that the current device meets the product specifications and will provide equivalent results to the predicate device.
9.6 Substantially Equivalent Determination:
From the above information we conclude that the new device (REEVUE) is substantially equivalent to the predicate device (BodyGem).
End of 510(k) Summary
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Image /page/20/Picture/0 description: The image is a black and white logo for the Department of Health & Human Services - USA. The logo features a circular design with the text "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" arranged around the perimeter. In the center of the circle is a stylized image of three faces in profile, stacked on top of each other.
Food and Drug Administratio 200 Corporate Boulevard Rockville MD 20850
JAN 02 2003
Dr. Scott A. Kofoed, Ph.D President Korr Medical Technologies, Incorporated 3900 East 3300 South, Suite 100 Salt Lake City, Utah 84109
- Re: K021490
Trade Name: REEVUE Indirect Calorimeter Regulation Number: 21 CFR 868.1730 Regulation Name: Oxygen-Uptake Computer Regulatory Class: II Product Code: BZL Dated: October 3, 2002 Received: October 4, 2002
Dear Dr. Kofoed:
We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration.
If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to such additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.
Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies.
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Page 2 - Dr. Kofoed
You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.
This letter will allow you to begin marketing your device as described in your Section 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please contact the Office of Compliance at (301) 594-4646. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21CFR Part 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers, International and Consumer Assistance at its toll-free number (800) 638-2041 or (301) 443-6597 or at its Internet address http://www.fda.gov/cdrh/dsma/dsmamain.html
Sincerely yours,
Timothy A. Ulatowski
Timothy A. Ulatowski Director Division of Anesthesiology, General Hospital, Infection Control and Dental Devices Office of Device Evaluation Center for Devices and Radiological Health
Enclosure
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KORR MEDICAL TECHNOLOGIES, INC REEVUE INDIRECT CALORIMETER
510(K) NOTIFICATION
Statement of Indications for Use
510(k) Number (if known):
....REEVUE Indirect Calorimeter Device Name: ..
Indications for Use:.................The REEVUE is intended for use in clinical and research applications to measure oxygen uptake.
(PLEASE DO NOT WRITE BELOW THIS LINE - CONTINUE ON ANOTHER PAGE IF NEEDED)
Concurrence of CDRH, Office of Device Evaluation (ODE)
Prescription Use
(Per 21 CFR 801.109)
OR
Over-The-Counter Use
HWootdn
(Bivision Sign-Off) Division of Anesthesiology, General Hospital, Infection Control, Dental Devices
510(k) Number:
Page vii
§ 868.1730 Oxygen uptake computer.
(a)
Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by a patient and may include components for determining expired gas volume and composition.(b)
Classification. Class II (performance standards).