(126 days)
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).
| Acceptance Criteria (from text) | Reported Device Performance (from text) |
|---|---|
| Comparative Performance: Correlation with IMED-Z system when using a test fixture representing different 'humans'. | SOZO system showed a very strong correlation (r > 0.99) compared to the cleared ZOE system (Note: ZOE is an NMT, Inc. device listed as a reference device, not the direct predicate IMED-Z mentioned in the test. This might be a typo in the document or indicates ZOE was also used for comparison.) |
| Electrical safety/EMC: Meet requirements set forth in IEC 60601 (subparts -1, -1-2, and -1-6). | Meets electrical safety and EMC requirements, CB certificate granted. |
| Software V&V: Software verified and validated to meet acceptance criteria and perform as intended. | Performed in accordance with ISO 62304; software was verified and validated to meet acceptance criteria and perform as intended. |
| Biocompatibility: Meet requirements set forth in ISO 10993 for a low risk, limited contact device. | Passed biocompatibility testing with no failures reported. |
| Functional performance: Expected to remain functional throughout its intended life. | Testing showed that the system is expected to remain functional throughout its intended life. |
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.
§ 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.