SOZO

The SOZO device is designed to aid clinicians in the assessment of lymphedema in adult patients who have undergone lymph node interventions, by non-invasively measuring extracellular fluid differences between limbs. It employs bioimpedance spectroscopy, applying a low-level, multi-frequency electrical current and analyzing the body's response to generate an L-Dex score, which quantifies impedance ratios indicative of fluid imbalances.

The SOZO® system by ImpediMed Limited is a body fluid analyzer intended for adult human patients at risk of lymphedema, particularly those who have undergone lymph node removal, damage, or irradiation in the axillary and/or pelvic regions. It functions as a bioimpedance spectroscopy (BIS) device, aiding clinicians in assessing lymphedema by measuring extracellular volume differences between the limbs. The system comprises a connected hand and footplate with stainless steel electrodes, an Android tablet running the "SOZOapp," and a "SOZOhub" database within the facility's network. During a 30-second measurement, the patient makes contact with the electrodes, and the device applies a 200µA RMS electrical current across 256 frequencies (3kHz to 1000kHz), measuring resulting voltage levels to calculate an L-Dex® score representing the impedance ratio. The underlying technology of the SOZO system measures impedance (Z), resistance (R), and reactance (Xc) to estimate extracellular fluid ratios. Performance data confirm its functionality and safety: it meets IEC 60601 for electrical safety/EMC, ISO 62304 for software, and ISO 10993 for biocompatibility. Functional testing indicates design reliability throughout its intended life. Clinical studies support the applicability of ImpediMed's BIS technology for lymphedema assessment, demonstrating a strong correlation of extracellular fluid levels between at-risk and ipsilateral limbs. Comparative performance testing using a test fixture to simulate different human impedance loads showed the SOZO system had a very strong correlation (r > 0.99) in outputs when compared against other ImpediMed systems like the U400 and SFB7, indicating the SOZO system functions as intended.

AI Regulatory Concerns

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Jev reads the full FDA letter and returns calibrated concern probabilities per regulatory category. These are AI estimates, not regulatory advice.

• Q1. How does the L-Dex score quantitatively correlate with established clinical staging systems for lymphedema (e.g., ISL stages)?; What is the reported sensitivity and specificity of the SOZO device for detecting early or subclinical lymphedema in the indicated patient population?; How do variations in patient hydration status, body mass index (BMI), or concurrent medical conditions potentially influence the L-Dex score accuracy?; The device measures extracellular volume differences between limbs; how does it aid in the assessment of bilateral lymphedema where a healthy contralateral limb for comparison might not be available or also affected?; What is the recommended frequency of SOZO measurements for optimal monitoring of lymphedema development or progression in at-risk patients post-lymph node intervention?