(193 days)
The L-Dex U400: A bioelectrical impedance analyzer/monitor utilizing impedance ratios that supports the measurement of extra cellular fluid volume differences between the arms to aid in the clinical assessment of unilateral lymphedema of the arm in women. This device is not intended to diagnose or predict lymphedema of an extremity.
Lymphedema Analysis PC Software – an optional PC software package that is intended to be used only with the ImpediMed L-Dex U400 analyzer/monitor for uploading data on to the PC from the L-Dex U400. processing and analyzing of bioimpedance measurements.
The L-Dex U400 is a multi frequency bioelectrical impedance analyser. The device accurately measures current, voltage and phase angle, and calculates impedance, resistance and reactance as with the XCA. These measurements and calculations are used to estimate extra cellular fluid (ECF) allowing for the assessment of the development of unilateral Lymphedema of the arms.
The ImpediMed L-Dex U400 Extra Cellular Fluid Analyzer, like the SFB7, is a battery powered, accurate, multi frequency, bioelectrical impedance analysis instrument operating in tetra-polar mode. The device accurately measures current, voltage and phase angle, and calculates impedance, resistance and reactance.
The provided text does not contain detailed information about specific acceptance criteria for the device or a study explicitly proving the device meets these criteria in the comprehensive manner requested. The document is primarily a 510(k) summary for the ImpediMed L-Dex U400, focusing on its intended use, device description, and technological characteristics, and stating its substantial equivalence to predicate devices.
However, based on the available information, here's what can be extracted and inferred:
1. A table of acceptance criteria and the reported device performance:
The document doesn't explicitly state quantitative acceptance criteria or detailed performance metrics from a study for the L-Dex U400. It describes the device's function and its intended use, emphasizing its ability to accurately measure current, voltage, and phase angle, and calculate impedance, resistance, and reactance to estimate extracellular fluid (ECF) for the assessment of unilateral lymphedema.
The statement "The device accurately measures current, voltage and phase angle, and calculates impedance, resistance and reactance as with the XCA" and "The ImpediMed L-Dex U400, like the SFB7, is a battery powered, accurate, multi frequency, bioelectrical impedance analysis instrument operating in tetra-polar mode" implies that its performance is considered comparable and accurate to its predicate devices.
Acceptance Criteria (Inferred from device description and intended use):
| Acceptance Criteria (Inferred) | Reported Device Performance (Inferred) |
|---|---|
| Accurate measurement of current, voltage, and phase angle. | "The device accurately measures current, voltage and phase angle..." |
| Accurate calculation of impedance, resistance, and reactance. | "...and calculates impedance, resistance and reactance as with the XCA." |
| Estimation of Extra Cellular Fluid (ECF) supporting assessment of unilateral lymphedema. | "These measurements and calculations are used to estimate extra cellular fluid (ECF) allowing for the assessment of the development of unilateral Lymphedema of the arms." and "...to convert measured impedance to a corresponding estimate of extra cellular fluid ratio (extra cellular fluid index or lymphedema index referred to as L-Dex), and differences between the arms. These estimates can be used as alternatives to the current circumferential measurements and water immersion methods, to indicate trends toward the potential development of Lymphedema." |
| Operation as a multi-frequency bioelectrical impedance analyzer in tetra-polar mode. | "The L-Dex U400 is a multi frequency bioelectrical impedance analyser." and "The ImpediMed L-Dex U400... is a battery powered, accurate, multi frequency, bioelectrical impedance analysis instrument operating in tetra-polar mode." |
| Equivalent performance to predicate devices (Imp XCA and Imp SFB7). | "The device accurately measures current, voltage and phase angle, and calculates impedance, resistance and reactance as with the XCA." and "The ImpediMed L-Dex U400... like the SFB7..." |
| Functionality in a specified frequency range (4kHz to 1000kHz). | "...small alternating constant current of 200uA RMS at a frequency of 4kHz+ 100Hz to 1000 kHz+" |
| Ability to be checked with a calibration circuit for quality assurance. | "The performance of the device may be checked with the aid of a calibration circuit (supplies as an accessory) for quality assurance or servicing purposes." |
2. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)
The provided document does not mention any specific test set sample size or data provenance details (e.g., country of origin, retrospective/prospective) related to a study for the L-Dex U400's performance validation. The 510(k) summary focuses on substantial equivalence to predicate devices rather than a de novo clinical study with a specific test set.
3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)
This information is not provided in the document.
4. Adjudication method (e.g. 2+1, 3+1, none) for the test set
This information is not provided in the document.
5. If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance
The document does not describe a multi-reader multi-case (MRMC) comparative effectiveness study, nor does it mention AI assistance. This device is a bioelectrical impedance analyzer, not an AI-powered diagnostic imaging tool that would typically involve human readers.
6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done
The device itself is a standalone instrument that measures bioelectrical impedance. The Lymphedema Analysis PC Software is an optional component for data upload, processing, and analysis. Its functionality is described as "algorithm only" in the sense that it converts measured impedance into an estimate of the L-Dex index based on "simple mathematics, bioelectrical and anthropometric parameters from peer reviewed published journal articles." The document does not explicitly present a "standalone performance study" in the context of an algorithm's diagnostic accuracy against a ground truth, but rather describes its operational capabilities and the basis of its calculations.
7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.)
The document states that the device's estimates "can be used as alternatives to the current circumferential measurements and water immersion methods, to indicate trends toward the potential development of Lymphedema." This implies that the accepted "ground truth" or reference methods for assessing lymphedema, which the L-Dex aims to provide an alternative for, are circumferential measurements and water immersion. The underlying validation of the mathematical models used to convert impedance to the L-Dex index relies on "peer reviewed published journal articles."
8. The sample size for the training set
The document does not mention a "training set" in the context of a machine learning model. The device's calculations are based on established bioelectrical impedance principles and parameters derived from "peer reviewed published journal articles," which would imply an empirical basis rather than a data-driven training set for an AI model.
9. How the ground truth for the training set was established
As there is no mention of a "training set" for an AI model, this information is not applicable. The basis for the device's calculations and interpretation (the L-Dex index) comes from scientific literature and established methods for studying extracellular fluid and lymphedema, which would have their own ground truth establishment methods (e.g., clinical diagnosis, volumetric measurements, expert assessment).
§ 870.2770 Impedance plethysmograph.
(a)
Identification. An impedance plethysmograph is a device used to estimate peripheral blood flow by measuring electrical impedance changes in a region of the body such as the arms and legs.(b)
Classification. Class II (special controls). The device, when it is a body composition analyzer which is not intended to diagnose or treat any medical condition, is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to the limitations in § 870.9.