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 fluid volume differences between the limbs and is presented to the clinician on an L-Dex scale as an aid to their clinical assessment of unilateral lymphedema of the arm and leg in women and the leg in men. The device is only indicated for patients who will have or who have had lymph nodes, from the axillary and pelvic regions, either removed, damaged or irradiated. SOZOhub PC software - a PC software package that is intended to be used only with the ImpediMed SOZO device for uploading data on to the PC from the SOZO device, processing and analyzing of bioimpedance measurements.
Device Story
SOZO system measures bioimpedance to assess extracellular fluid volume differences; utilizes stainless steel electrodes on hand/footplates; inputs include electrical current (~200uA RMS) across 256 frequencies (3kHz-1000kHz). Device measures current, voltage, and phase angle to calculate impedance, resistance, and reactance; transforms data into L-Dex ratio via established algorithms. Operated by clinicians in hospital/facility settings; system includes hardware, Android tablet with SOZOapp, and SOZOhub PC software for data management. Output presented as L-Dex score on scale; aids clinician in lymphedema assessment. Benefits include non-invasive, rapid (30s) measurement of fluid volume differences to support clinical decision-making.
Clinical Evidence
Bench testing only. Comparative performance study using test fixtures representing fixed impedance loads demonstrated strong correlation (r > 0.99) between SOZO and predicate U400 system. Biocompatibility testing per ISO 10993 passed. Electrical safety and EMC testing per IEC 60601 series confirmed compliance. Functional reliability testing confirmed device durability.
Technological Characteristics
Bioimpedance spectroscopy; stainless steel electrodes; 256 frequencies (3kHz-1000kHz); 200uA RMS current. Measures impedance (Z), resistance (R), reactance (Xc). Wall-powered; Bluetooth connectivity to Android tablet; Wi-Fi to PC database. Standards: IEC 60601-1, IEC 60601-1-2, IEC 60601-1-6, ISO 62304, IEC 62366, ISO 10993-1/5/10.
Indications for Use
Indicated for adult patients who have had or will have axillary or pelvic lymph node removal, damage, or irradiation, to aid clinical assessment of unilateral lymphedema of the arm and leg in women and the leg in men.
Regulatory Classification
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.
Special Controls
*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.
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Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002
August 11, 2017
ImpediMed Limited % Reuben Lawson Senior Director, Regulatory Affairs and Clinical ImpediMed Inc. 5900 Pasteur Court, Unit 125 Carlsbad. CA 92008
Re: K172122 Trade/Device Name: SOZO™ Regulation Number: 21 CFR§ 870.2770 Regulation Name: Impedance Plethysmograph Regulatory Class: II Product Code: OBH Dated: July 13, 2017 Received: July 13, 2017
Dear Reuben Lawson:
We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food. Drug. and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.
If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.
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Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801); medical device reporting (reporting of medical devicerelated adverse events) (21 CFR 803); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820); and if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.
If you desire specific advice for your device on our labeling regulation (21 CFR Part 801), please contact the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address
http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to
http://www.fda.gov/MedicalDevices/Safety/ReportaProblem/default.htm for the CDRH's Office of Surveillance and Biometrics/Division of Postmarket Surveillance.
You may obtain other general information on your responsibilities under the Act from the Division of Industry and Consumer Education at its toll-free number (800) 638-2041 or (301) 796-7100 or at its Internet address
http://www.fda.gov/MedicalDevices/ResourcesforYou/Industry/default.htm.
Sincerely,
Joyce M. Whang -S
for
Benjamin R. Fisher, Ph.D. Director Division of Reproductive, Gastro-Renal, and Urological Devices Office of Device Evaluation Center for Devices and Radiological Health
Enclosure
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## DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Druq Administration Indications for Use
Form Approved: OMB No. 0910-0120 Expiration Date: January 31, 2017 See PRA Statement on last page
| 510(k) Number (if known) | K172122 |
|--------------------------|---------|
|--------------------------|---------|
sozo™ Device Name
Indications for Use (Describe)
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 fluid volume differences between the limbs and is presented to the clinician on an L-Dex scale as an aid to their clinical assessment of unilateral lymphedema of the arm and leg in women and the leg in men.
The device is only indicated for patients who will have or who have had lymph nodes, from the axillary and pelvic regions, either removed, damaged or irradiated.
SOZOhub PC software - a PC software package that is intended to be used only with the ImpediMed SOZO device for uploading data on to the PC from the SOZO device, processing and analyzing of bioimpedance measurements.
| Type of Use (Select one or both, as applicable) |
|--------------------------------------------------------------------------------------------------------------------------------------|
| <span> ☒ Prescription Use (Part 21 CFR 801 Subpart D) </span> <span> ☐ Over-The-Counter Use (21 CFR 801 Subpart C) </span> |
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#### 510(k) SUMMARY
## ImpediMed's SOZO system
## Submitter:
| ImpediMed Limited<br>Unit 1<br>50 Parker Court<br>Pinkenba Qld 4008<br>Australia | |
|----------------------------------------------------------------------------------|-------------------------------------------|
| Phone: | 760 585 2104 |
| Facsimile: | 760 804 9245 |
| Contact Person: | Reuben Lawson |
| Date Prepared: | July 13, 2017 |
| Name of Device: | SOZO |
| Common or Usual Name: | Body Fluid Analyzer |
| Classification Name: | Impedance Plethysmograph |
| Regulatory Class: | 21 CFR 820.2770 |
| Product Code: | OBH |
| Predicate Devices | ImpediMed Limited's L-Dex® U400 (K130338) |
#### Device Description
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 limbs, and present the impedance ratio as an L-Dex® score for the clinician to review. This score facilitates their clinical assessment of unilateral lymphedema of the arm and leg in woman, and the leg in men.
#### Intended Use/Indications for Use
A bioimpedance spectroscopy device for use on adult human patients, utilizing impedance ratios
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that are displayed as an L-Dex ratio that supports the measurement of extracellular fluid volume differences between the limbs and is presented to the clinician on an L-Dex scale as an aid to their clinical assessment of unilateral lymphedema of the arm and leg in women and the leg in men.
The device is only indicated for patients who will have or who have had lymph nodes, from the axillary and pelvic regions, either removed, damaged or irradiated.
SOZOhub PC software - a PC software package that is intended to be used only with the ImpediMed SOZO device for uploading data on to the PC from the SOZO device, processing and analyzing of bioimpedance measurements.
# Summary of Technological Characteristics
Bioimpedance spectroscopy is the technological principle for both the subject and predicate devices. The subject and predicate devices are based on the following same fundamental technological elements:
- . Use of electrodes to take measurements; two 'drive' and two 'sense' channels are used to measure each side of the body;
- . 'Drive' channels deliver very low levels of current (~200ua RMS) across 256 frequencies logarithmically spaced from 3kHz to 1000kHz;
- . 'Sense' channels measure current (I), voltage (V) and phase angle (Ph), and calculates three bioimpedance parameters: impedance (Z), resistance (R) and reactance (Xc) to estimate extracellular fluid ratios, and calculate the impedance ratios which are converted to a L-Dex ratio:
- Data is stored in and accessed from a local database (SOZOhub) utilizing separate software . installed on a network connected PC.
Minor technological differences exist between the subject and predicate devices:
- . SOZO utilizes a revamped external housing, which is directly patient-contacting and uses stainless steel electrodes for taking bioimpedance measurements;
- . SOZO is wall powered rather than battery powered;
- . SOZO is controlled through an Android app on a supplied tablet, which is paired to the SOZO hardware over Bluetooth connection, and connects with the local database over Wi-Fi.
# Purpose of 510(k)
The purpose of this 510(k) is to clear the design changes presented in the SOZO system.
These changes are intended to provide a faster, more streamlined customer experience with a more aesthetically pleasing design.
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## Performance Data
The SOZO system has gone through appropriate testing per design controls to confirm the new design's functionality and performance.
Electrical safety/EMC: testing was performed according to the requirements set forth in IEC 60601 (subparts -1, -1-2, and -1-6). It was determined that the SOZO device meets electrical safety and EMC requirements, and CB certificate was granted for the system.
Software V&V: the same level of concern software documentation as the predicate device was created and testing performed in accordance with ISO 62304. The software was verified and validated to meet acceptance criteria and perform as intended.
Biocompatibility: testing was performed by an accredited third party according to the requirements set forth in ISO 10993 for a low risk, limited contact device. It was determined that the SOZO system passed biocompatibility testing with no failures reported.
Comparative performance vs. predicate device: using a test fixture to create multiple fixed impedance loads representing different 'humans', a SOZO system was compared against a U400 system to verify correlation in L-Dex readings. The SOZO system showed a very strong correlation (r > 0.99) compared to the cleared U400 system.
Functional performance: multiple SOZO systems were tested for design reliability by repeatedly placing weights on the components that encounter the most physical stress. Testing showed that the system is expected to remain functional throughout its intended life.
# Conclusions
The SOZO system has the same intended uses /indications, and similar technological characteristics, and principles of operation as its predicate device. In addition, the minor technological differences between the SOZO system and its predicate device raise no new or different issues of safety or effectiveness. Design controls demonstrate that the SOZO system is as safe and effective as the cleared device version. Thus, the SOZO system is substantially equivalent.
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#### IX. PERFORMANCE STANDARDS
No performance standards or special controls have been developed under Section 514 of the FDC Act for a monitor of extracellular fluid (lymphedema) in an extremity. No special controls apply.
Consistent with FDA's guidance document entitled "Use of Standards in Substantial Equivalence Determinations' (March 12, 2000) and "Guidance for Industry and FDA Staff - Recognition and Use of Consensus Standards" (September 17, 2007), ImpediMed Limited is including this statement that the SOZO system complies with the following recognized consensus standards:
- IEC 60601-1:2005/A1:2012 General Electrical and Mechanical Safety; ●
- IEC 60601-1-2:2014 Ed4.0 Electromagnetic Compatibility; ●
- IEC 60601-1-6:2010/A1:2013 Usability ●
- EN/ISO 62304:2006 Medical device software Software life-cycle processes; ●
- IEC 62366:2007/A1:2014 Application of usability engineering to medical devices;
- ISO 10993-1:2009/TC1:2010 Biological Evaluation of Medical Devices;
- ISO 10993-5:2009. Cytotoxicity: ●
- ISO 10993-10:2010, Test for Irritation and Skin Sensitization.
A Data Standards Form (FDA Form 3654) is provided in Attachment 1 for each listed recognized consensus standard.
Two short videos show you everything — or skip straight to the written tutorial if you'd rather read. You can reopen this any time from the Tutorial button in the top bar.
Part 1 — Search, results, and everyday workflows 16 min
Part 2 — Embeddings: the galaxy map 3 min
1. Search: exact and fuzzy
Type a phrase like "coronary artery calcification" into the search box. You get two kinds of results. Exact results match the literal phrase — prefix searches work ("coronary artery calcificati") but suffix searches do not. Fuzzy results match on the meaning and intent of your phrase rather than the exact words, and are sorted by relevance score. Hover over the Exact or Fuzzy badge on any row to see exactly why it matched.
Use the checkboxes above the results to narrow: SaMD keeps only software-only devices, AI / ML keeps only devices with AI.
Exact vs. fuzzy search: what's the difference?
Exact matches on the literal phrase (prefix search works, suffix does not). Fuzzy matches on the meaning and intent of the phrase rather than the exact words. Hover over the badge on any row to see why it matched.
You search "coronary artery calcification" and want only software devices with AI. What two filters do you apply?
Narrow by SaMD (software-only devices), then narrow by AI/ML (devices with AI).
2. The results table
Scroll right in the results table. The intended use is extracted for you — no need to open the PDF. The device story gives a high-level snapshot of what the device does and how it's used. The AI Performance sub-table shows each output name, acceptance criteria, observed values, and development/test dataset descriptions — the same format Innolitics uses for regulatory strategy outputs, and the fastest high-level fingerprint of an AI device. It is AI-generated but has been very reliable in practice.
Where do you find a device's intended use without opening the PDF?
Scroll right in the search results table. The intended use column is extracted for you; no need to dig into the 510(k) summary PDF.
What does the AI Performance sub-table show, and why is it useful?
Output name, acceptance criteria, observed values, development dataset description, and test dataset description. It's the same format we use for regulatory strategy output and Fast 510(k) input, and the fastest high-level fingerprint of an AI device. AI-generated but reliable in practice.
3. Judging fuzzy relevance
Fuzzy results trail off in relevance as you scroll. Use three signals to decide how far down to go: the fuzzy badge explanations, the intended use column, and whether your target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, you're past the relevant zone. A top hit with a low score (~0.4) and a stretched explanation is a hint the closest predicates are far away — the project may be headed for De Novo. Note the fuzzy search is a pattern match: it doesn't handle negation ("not") well, and hardware devices can appear — filter by SaMD/AI ML to cut them.
How do you judge how far down fuzzy search results to go?
Use the relevancy signals: the fuzzy badge explanations, the intended use column, and whether the target output (e.g., Cobb angle) still appears in the AI Performance sub-table. Once it stops appearing, results are trailing off in relevancy.
4. Device detail page: chat and citations
Click a device name to open its detail page: device facts on the left, a chat window on the right. Ask something like "Describe the training data". The answer carries little citation bubbles — click one to jump to the highlighted passage in the source PDF, so you can verify every AI answer against the document. There's also a Download PDF button for sharing.
How do you verify an AI chat answer on the device detail page?
Click the citation bubbles to jump to the relevant highlight in the source document.
Reading rule for every project: how many summaries do you read in full?
At least the three most relevant 510(k) or De Novo summaries, in full. After that, use targeted chat questions to confirm your memory quickly. The tool supports this professional habit — it doesn't replace it.
5. Side-by-side comparison
Select multiple rows in the results table (aim for under ~10), then open the PDF Viewer tab. Ask one question — it goes to all selected devices in parallel, each with citations. This is the fastest way to compare and contrast devices: training data, PCCP scope, how they handled adding new scanners, and so on.
What does the side-by-side PDF viewer mode do?
Select multiple devices, open the PDF viewer tab, and ask one question (e.g., "Describe the training data"). It queries all selected devices simultaneously with citations, so you can compare and contrast quickly.
6. Collections
With rows selected, go to the Collections tab and create a labeled collection (e.g., "Cobb Angle Project"). Reload that selection any time — before a client call, pull up the collection and ask questions across all of its devices at once.
How do you save a set of selected devices for later use?
Select the rows, go to the Collections tab, and create a labeled collection (e.g., "Cobb Angle Project"). You can reload the selection anytime and carry it into the PDF viewer and other tabs that support selections.
7. Product codes and the regulations tree
Click a product code in the results to jump to it in the regulations tree — identification text, sibling product codes, and devices you can open in a PDF viewer on the right. Click a regulation number to see its identification, special controls, and related product codes. You can also search by product code or regulation number at the top of the tree. Always read the special controls if any exist for your device — it broadens your search and sharpens pre-kickoff research.
What can you do from the regulations tree view?
Browse product codes and regulation numbers, read the identification text and special controls, browse sibling product codes, open device PDFs on the right, and search by product code or regulation number at the top of the tree.
8. Chart view
Click Show Chart and segment by regulation number (or product code) to see which regulations dominate your result set. Clicking a regulation takes you into the regulations tree. Great for spotting that most matches are, say, hardware laparoscopic devices — a cue to go back and filter.
How do you see which regulations dominate a search result set?
Click "Show Chart" and segment by Regulation Number. Clicking a regulation takes you to the regulations tree.
9. The predicate graph
Open the Predicates tab for a family-tree view of predicate relationships. Click a node to trace its parents and children; selections from search carry over pre-selected. Commonly predicated devices are worth reading — a lot of people predicated them for a reason. The visual lineage is also handy on client calls, e.g. to show how a predicate family evolved and justify why your predicate still holds.
In the predicate graph, why are commonly predicated devices worth reading?
A lot of people predicated them for a reason. Clicking a node traces parents and children, and selections from search carry over pre-selected.
10. Embeddings: the galaxy map
The Embeddings tab plots every matching document in a 2-D "galaxy map" where semantically similar devices cluster together. Hover or click clusters to explore, and let AI label the clusters for you. Embeddings beat product codes for grouping: two devices can carry different product codes (LLZ vs. QIH) yet do the same thing — the embedding captures the meaning of the intended use and device story. This is also exactly how retrieval-augmented generation (RAG) works under the hood, and it makes a great visual on client calls.
Try it yourself
Head to the search page and work through a few of these AI/ML fuzzy searches to build intuition: perivascular fat on CT · aortic valve calcification opportunistic screening on noncontrast CT · breast cancer prediction on digital pathology slides · autism detection · gestational age prediction · a hearing aid that can also detect a pulse · foundation model based analysis of ECG · large language models · penetration test. Watch how the relevance scores, intended use, and AI Performance tables tell you when results stop being meaningful.