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For adult human patients at risk of lymphedema:

A bioimpedance spectroscopy device for use on adult human patients, utilizing impedance ratios that are displayed as an L-Dex ratio that supports the measurement of extracellular volume differences between the limbs and is presented to the clinician on an L-Dex scale as an aid to their clinical assessment of lymphedema.

The use of the device to obtain an L-Dex score is only indicated for patients who will have or who have had lymph nodes, from the axillary and/or pelvic regions, either removed, damaged or irradiated.

The SOZO system consists of a connected hand and footplate with built-in stainless steel electrodes, paired with an Android tablet over Bluetooth connection. An app ("SOZOapp"), supplied with the tablet, controls the functionality of the hardware and supplies the bioimpedance measurement data to a database ("SOZOhub") contained within the hospital/facility network.

Measurements require the patient to make contact with bare hands and feet on stainless steel electrodes. The measurement takes about 30 seconds, during which the SOZO™ system applies small levels of electrical energy (200µA RMS) to the body across 256 frequencies spaced logarithmically from 3kHz to 1000kHz and measures the resulting voltage levels. Established algorithms are used to analyze data and calculate extracellular fluid impedance levels for left and right limbs, and present the impedance ratio as an L-Dex® score for the clinician to review. This score facilitates their clinical assessment of lymphedema in adult human patients.

The SOZO® device is a bioimpedance spectroscopy device intended for adult human patients at risk of lymphedema. It uses impedance ratios to display an L-Dex ratio, aiding clinicians in assessing lymphedema by measuring extracellular volume differences between limbs.

Here's an overview of the acceptance criteria and the study proving the device meets them:

1. Acceptance Criteria and Reported Device Performance:

2. Sample Size Used for the Test Set and Data Provenance:

The document does not explicitly state a specific sample size for the "clinical testing" mentioned, nor does it detail the provenance (country of origin, retrospective or prospective) of the data used for establishing the strong correlation of extracellular fluid levels. For the "comparative performance vs. predicate device" test, the "test set" consisted of a test fixture creating "multiple fixed impedance loads representing different 'humans'".

3. Number of Experts and Qualifications:

The document does not specify the number or qualifications of experts used to establish ground truth for any of the tests. For "clinical testing," it refers to "studies" that identified the applicability of the BIS technology, implying clinical expertise was involved in those studies, but no details are provided here.

4. Adjudication Method:

The document does not mention any adjudication method for establishing ground truth within the context of the provided performance data.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:

The document does not describe an MRMC comparative effectiveness study involving human readers with and without AI assistance. The device is presented as an "aid to their clinical assessment," suggesting a human-in-the-loop scenario, but no comparative effectiveness study of this nature is detailed.

6. Standalone (Algorithm Only) Performance Study:

A standalone performance study was conducted for the device. The comparative performance against the predicate device using a test fixture and the "clinical testing" demonstrating correlation of extracellular fluid levels support the algorithm's standalone performance in producing the L-Dex ratio.

7. Type of Ground Truth Used:

• For Electrical Safety/EMC, Software V&V, Biocompatibility, and Functional Performance, the ground truth was based on adherence to international standards and internal design specifications/requirements.
• For Clinical Performance, the ground truth seems to be implicitly derived from established clinical understanding of lymphedema and extracellular fluid levels, as evidenced by "studies (that) have identified the applicability of ImpediMed's BIS technology." While not explicitly stated as "expert consensus," the nature of clinical assessment of lymphedema often relies on expert judgment integrated with objective measures.
• For Comparative Performance vs. Predicate Device, the ground truth was established by comparing the SOZO system's outputs against the outputs of already established predicate devices (ImpediMed U400 and SFB7) when presented with the same "fixed impedance loads." This implies the predicate devices' outputs served as the reference or "ground truth" for correlation.

8. Sample Size for the Training Set:

The document does not explicitly mention a separate "training set" or its sample size. The "Established algorithms are used to analyze data" implies algorithms were developed and likely trained, but details about the training process are not provided in this summary.

9. How the Ground Truth for the Training Set Was Established:

This information is not provided in the document.

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The SOZO Fluid Status Monitor is intended for adult patients living with heart failure.

This device is intended for use, under the direction of a physician, for the noninvasive monitoring of patients with fluid management problems suffering from heart failure. Data from the device should be considered in conjunction with other clinical data.

The SOZO™ system consists of a connected hand and footplate with built-in stainless steel electrodes, paired with an Android tablet over Bluetooth connection. An app ("SOZOapp"), supplied with the tablet, controls the functionality of the hardware and supplies the bioimpedance measurement data to a database ("SOZOhub") contained within the hospital/facility network.

Measurements require the patient to make contact with bare hands and feet on stainless steel electrodes. The measurement takes about 30 seconds, during which the SOZO™ system measures small quantities of electrical energy (200uA RMS) across 256 frequencies, spaced logarithmically from 3kHz to 1000kHz. Established algorithms are used to analyze data and calculate extracellular fluid impedance levels for left and right sides of the body, and present the impedance levels for the clinician to review. These scores facilitate the clinician's monitoring and management of patients with fluid management problems in a variety of medically accepted clinical applications.

The provided text is a 510(k) Summary for the ImpediMed SOZO™ system. While it details the device's technical characteristics, intended use, and various validations (electrical safety, software V&V, biocompatibility, functional performance), it does not contain a specific performance study with acceptance criteria and reported device performance for its primary intended use of monitoring fluid status in heart failure patients.

The document focuses on demonstrating substantial equivalence to a predicate device (ImpediMed Limited's IMED-Z, K142503) by highlighting similar technological characteristics and showing that minor differences do not raise new safety or effectiveness issues.

Here's a breakdown of what is and isn't available based on the provided text:

1. Table of acceptance criteria and the reported device performance:

The document mentions "Comparative performance" but this is for demonstrating correlation between the new SOZO system and the predicate IMED-Z system using a "test fixture" (not human subjects).

Missing Information (Crucial for its Primary Indication):

The document does not provide acceptance criteria or performance data for the SOZO system's ability to accurately monitor fluid status in heart failure patients in a clinical setting. It states the purpose of the 510(k) is to clear design changes and indications, and relies on the "substantial equivalence" framework without presenting new clinical performance data for its intended use.

2. Sample size used for the test set and the data provenance:

• Test set for fluid status monitoring: Not applicable, as no human subject clinical performance study is described for its intended use.
• Comparative performance (test fixture): The "test fixture" represents "multiple fixed impedance loads," but the exact number of these simulated 'humans' or specific impedance loads is not stated. This is an engineering verification, not a clinical test.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

Not applicable, as no human subject clinical performance study is described. The "ground truth" for the comparative performance was the output of the predicate/reference device on a test fixture.

4. Adjudication method (e.g. 2+1, 3+1, none) for the test set:

Not applicable, as no human subject clinical performance study is described.

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:

Not applicable. The SOZO device is a bioimpedance measurement system that directly provides impedance levels, not an AI-assisted diagnostic tool interpreted by human readers in the sense of an MRMC study.

6. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done:

The device itself is a standalone measurement device. The "Comparative performance" section is the closest to a standalone evaluation, comparing the SOZO's output to another device's output on a test fixture. This is an algorithm-only comparison, but not against a clinical "ground truth" for fluid status monitoring.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc):

For the comparative performance: The "ground truth" was the measurements from the predicate/reference device (IMED-Z/ZOE) on a test fixture. This is a technical (device vs. device) comparison, not a clinical ground truth (e.g., fluid volume measured by another gold standard method, or clinical outcomes).

8. The sample size for the training set:

Not applicable. This device is described as using "Established algorithms" to analyze data and calculate impedance levels. It's not a machine learning model that would typically have a "training set" in the context of supervised learning for classification or prediction. The algorithms are based on bioimpedance principles rather than trained on a large dataset of patient outcomes.

9. How the ground truth for the training set was established:

Not applicable, as there is no mention of a training set for machine learning. The algorithms are described as "established" for bioimpedance analysis.

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