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The SOZO system may be used as an adjunct to existing methods by aiding clinicians who are using Subjective Global Assessment (SGA) tools to assess patients at risk of protein-calorie malnutrition (PCM).

The SOZO system may be further used to estimate the following body composition parameters in humans to track clinically relevant body composition parameters over time:

• Fat mass
• Fat-free mass
• Total body water
• Intracellular fluid
• Extracellular fluid
• Skeletal muscle mass

The following outputs are also presented:

• Body Mass Index (BMI)
• Basal metabolic rate (BMR; based on Mifflin - St. Jeor's algorithm) displayed in calories per day
• Protein and mineral (also known as 'dry lean mass') represents the content of a body that is not fat or fluid; calculated by subtracting total body water weight from fat-free mass weight.

The SOZO device measures current (I), voltage (V) and phase angle (Phi), and from these values calculates resistance (R), reactance (Xc), and impedance (Z), which are used to estimate the above body composition parameters. The device/software will also display the Cole plot, subject height, weight, age and sex.

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 current (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 various body composition parameters and present the outputs for the clinician to review.

Here's an analysis of the acceptance criteria and study information provided in the document:

1. Table of Acceptance Criteria and Reported Device Performance

2. Sample Sizes Used for the Test Set and Data Provenance

The document does not explicitly state a specific "test set" sample size for a clinical study to directly prove the new indications for use. Instead, it states: "Clinical testing: clinical studies have identified the applicability of ImpediMed's BIS technology to act as an aid in body composition." This general statement implies that the underlying Bioimpedance Spectroscopy (BIS) technology has been validated through clinical studies, but it doesn't provide details about studies specific to the SOZO system's new indications or a dedicated test set with sample size.

For the comparative performance with the predicate device, a "test fixture" was used with "multiple fixed impedance loads," which isn't a human sample size but rather an engineering test.

Data Provenance: Not explicitly stated for specific clinical studies, only generally refers to "clinical studies."

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Their Qualifications

This information is not provided in the document. The document refers to "clinical studies" for the applicability of BIS technology but does not detail how ground truth was established for these studies, nor the number or qualifications of experts involved.

4. Adjudication Method 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, and the Effect Size of Improvement with AI vs. Without AI Assistance

No MRMC study is mentioned in the document. The SOZO system is a device for measuring body composition parameters, not an AI-assisted diagnostic tool for human readers in the traditional sense of an MRMC study. Its use is described as "an adjunct to existing methods by aiding clinicians who are using Subjective Global Assessment (SGA) tools," but no study comparing human performance with and without SOZO assistance is described.

6. If a Standalone (Algorithm Only Without Human-in-the-Loop Performance) Was Done

The device itself is a standalone measurement system that takes raw electrical measurements and processes them using "established algorithms" to calculate body composition parameters. The "comparative performance vs. predicate device" test (r > 0.99 correlation) can be considered a standalone performance assessment against a validated reference.

7. The Type of Ground Truth Used

• For Body Composition Parameters: The document states that "established algorithms are used to analyze data and calculate various body composition parameters." For the "comparative performance vs. predicate device," the predicate device (SFB7) is essentially the reference standard (ground truth surrogate). However, for the initial validation of the BIS technology to derive these parameters, it is generally understood that such systems are validated against gold standard body composition assessment methods (e.g., DEXA, isotope dilution, direct chemical analysis), though this specific detail is not provided for the SOZO system in this document. The document refers to "clinical studies have identified the applicability of ImpediMed's BIS technology to act as an aid in body composition," implying prior validation work.
• For Protein-Calorie Malnutrition (PCM) Assessment: The device is used as an adjunct to Subjective Global Assessment (SGA) tools, implying that SGA is the primary assessment method clinicians use.

8. The Sample Size for the Training Set

No training set sample size is explicitly mentioned. The device uses "established algorithms," suggesting that the algorithms were developed and potentially trained on datasets prior to this submission. This document focuses on the performance and equivalence of the SOZO device itself, not the detailed development of its underlying algorithms.

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

This information is not provided in the document. As with the training set size, the document does not delve into the historical development and validation of the "established algorithms" that process the bioimpedance data.

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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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