SOZO

The SOZO™ system is a non-invasive bioimpedance spectroscopy device designed to quantify extracellular fluid differences between limbs by measuring electrical impedance across a range of frequencies. It aids clinicians in the assessment of unilateral lymphedema in at-risk adult patients by providing an L-Dex® ratio, an objective measure reflecting these fluid imbalances.

The SOZO™ system by ImpediMed Limited is a bioimpedance spectroscopy device designed to aid clinicians in assessing unilateral lymphedema in adult patients who have undergone lymph node removal, damage, or irradiation in the axillary or pelvic regions. Its methodology involves the patient making direct contact with stainless steel electrodes on a connected hand and footplate. Over approximately 30 seconds, the system applies a low-level electrical current (200 μA RMS) across a wide range of 256 frequencies (3kHz to 1000kHz), measuring current, voltage, and phase angle to calculate bioimpedance parameters, which are then used to estimate extracellular fluid levels in the limbs. The core output of the SOZO system is an L-Dex® ratio, derived from the impedance ratios between the left and right limbs, quantifying extracellular fluid volume differences to assess unilateral lymphedema of the arm and leg in women, and the leg in men. This L-Dex score is presented to the clinician on a scale to assist in their clinical assessment. The system includes an Android tablet with the "SOZOapp" for controlling the hardware via Bluetooth and transmitting measurement data via Wi-Fi to the "SOZOhub," PC software for data uploading, processing, and analysis. Performance testing confirmed electrical safety, biocompatibility, software validity, and functional reliability, with comparative studies against its predicate (L-Dex® U400) showing strong correlation (r > 0.99) in L-Dex readings.

AI Regulatory Concerns

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• Q1. How does the L-Dex ratio correlate with established clinical lymphedema staging systems, and what is the sensitivity and specificity of the SOZO device in detecting early-stage lymphedema compared to other diagnostic modalities?; What is the inter-operator and intra-operator variability of L-Dex measurements using the SOZO system, and what factors (e.g., patient positioning, hydration status) most significantly influence measurement accuracy?; Are there specific patient populations (e.g., those with comorbidities like congestive heart failure or renal disease) where the interpretation of L-Dex scores might be confounded or require adjustment?; How does the range of 256 frequencies (3kHz to 1000kHz) used by SOZO optimize the differentiation of extracellular fluid, and are there particular frequency sub-ranges that contribute most significantly to the L-Dex calculation?; Beyond unilateral lymphedema, what other potential clinical applications could leverage SOZO's bioimpedance spectroscopy technology for assessing fluid status or body composition, given its measurement capabilities?