The L-Dex® U400 is 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. Lymphedema Analysis PC Software - an optional PC software package that is intended to be used only with the ImpediMed L-Dex U400 device for uploading data on to the PC from the L-Dex U400, processing and analyzing of bioimpedance measurements.
Device Story
L-Dex U400 is a battery-powered bioimpedance spectroscopy device. It measures current, voltage, and phase angle via tetra-polar leads and self-adhesive skin electrodes. It operates across a frequency range of 4–1000 kHz (256 data points). The device calculates impedance (Z), resistance (R), and reactance (Xc) to estimate extracellular fluid ratios and generate an L-Dex ratio. Used in clinical settings by healthcare providers to assess unilateral lymphedema. Output is displayed on-screen as a resistance vs. reactance complex impedance plot and an L-Dex value. Data can be transferred to Impsoft PC software for history tracking and report generation. The device aids clinicians in monitoring fluid volume differences, potentially facilitating earlier lymphedema detection and management.
Clinical Evidence
No clinical data provided; reliance on literature reports describing device use for the indicated purpose.
Technological Characteristics
Battery-powered bioimpedance spectroscopy device; tetra-polar mode; 4–1000 kHz frequency range; 256 data points; dimensions 190mm x 130mm x 110mm; weight 1 kg; connectivity via data transfer to Impsoft database software.
Indications for Use
Indicated for adult patients who have had or will have lymph nodes in the axillary or pelvic regions removed, damaged, or irradiated, to aid in the 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.
Predicate Devices
L-Dex® U400 BIS Extra Cellular Fluid Analysis (K100811)
Submission Summary (Full Text)
{0}------------------------------------------------
#### 510(k) SUMMARY
#### lmpediMed Limited's L-Dex® U400
## MAY 3 1 2013
### Submitter's Name, Address, Telephone Number, Contact Person and Date Prepared
| Company Name and Address: | ImpediMed Limited<br>Unit 1<br>50 Parker Court<br>Pinkenba, QLD - 4008<br>Australia |
|---------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Contact Person: | Catherine Kingsford<br>Vice President of Clinical and Regulatory Affairs and<br>Intellectual Property<br>Phone: (+61) 7 3860 3700 Ext 1225<br>Fax: (+61) 7 3260 1225<br>E-mail: ckingsford@impedimed.com |
| Date of summary prepared: | February 8, 2013 |
#### Proprietary Device Name / Common Name / Classification
| Trade/Proprietary name: | L-Dex® U400 BIS Extra Cellular Fluid Analysis |
|--------------------------------|-----------------------------------------------|
| Classification name: | Impedance Plethysmograph |
| Regulation number/CFR section: | 21 C.F.R. § 870.2770 |
| Product code: | OBH |
| Regulation Medical Specialty: | Cardiovascular |
| Review Panel: | Gastroenterology/Urology |
| Device class: | Class II |
#### Predicate Devices
ImpediMed Limited, L-Dex® U400 BIS Extra Cellular Fluid Analysis (K100811)
.
#### Intended Use / Indications for Use
The L-Dex® U400 is 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.
{1}------------------------------------------------
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.
Lymphedema Analysis PC Software - an optional PC software package that is intended to be used only with the ImpediMed L-Dex U400 device for uploading data on to the PC from the L-Dex U400, processing and analyzing of bioimpedance measurements.
#### Technological Characteristics / Principles of Operation
The ImpediMed L-Dex U400 Extra Cellular Fluid Analysis device is a battery powered bioimpedance spectroscopy device operating in tetra-polar mode via a set of leads that are attached to self-adhesive skin electrodes by means of alligator clips. The subject device accurately measures current, voltage and phase angle, and cakulates three bioimpedance parameters: impedance (Z), resistance (R) and reactance (Xc). These measurements and calculations are used to estimate extracellular fluid ratios, and calculate the Lymphedema Index or L-Dex
The L-Dex U400 measures bioimpedance parameters over a frequency range of 4 - 1000 kHz with 256 data points. An on-screen graph displays the raw measured data in the form of a resistance vs. reactance complex impedance plot. These bioelectrical parameters are then used in algorithms to give an L-Dex value for the affected compared to the unaffected limb.
Measured impedance ratios (L-Dex values) and normal ranges are shown on the device immediately after measurement and stored for later reference. Measured data may be transferred to the ImpediMed Impsoft database software. The Impsoft software adds extra functionality and ease of data management, including viewing patient histories and printing reports.
#### Performance Data
The company has provided an overview of reports in the literature that describes the use of the device for its indications for use.
#### Substantial Equivalence
The L-Dex U400 is as safe and effective as the company's cleared device of the same name (K100811). The L-Dex U400 has the same intended use, technological characteristics, and principles of operation and similar indications as its predicate device. The minor change in indications for use between the subject and cleared device does not impact the diagnostic effect of the L-Dex U400. Performance data demonstrate that the subject device is as safe and effective as the company's predicate device for the proposed indications for use. Thus, the L-Dex U400 is substantially equivalent.
{2}------------------------------------------------
| | Subject Device | Predicate Devices | |
|--------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| K Number | L-Dex® U400 | K080825 | |
| Class | Class II | Class II | |
| Regulation | 870.2770 | 870.2770 | |
| Common Name | L-Dex | L-Dex | |
| Intended Use | A bioimpedance spectroscopy device for<br>use on adult human patients, utilizing<br>impedance ratios that are displayed as<br>an L-Dex ratio that supports the<br>measurement of extracellular fluid<br>volume differences between the limbs<br>and is presented to the clinician on an L-<br>Dex scale as an aid to their clinical<br>assessment of unilateral lymphedema of<br>the arm and leg in women and the leg in<br>men. | A bioelectrical impedance<br>analyzer/monitor for use on adult human<br>patients, utilizing impedance ratios that<br>are displayed as an L-Dex ratio that<br>supports the measurement of<br>extracellular fluid volume differences<br>between the limbs and is presented to<br>the clinician on an L-Dex scale as an aid<br>to their clinical assessment of unilateral<br>lymphedema of the arm and leg in<br>women and the leg in men. | A bioelectrical impedance<br>analyzer/monitor utilizing impedance<br>ratios that supports the measurement of<br>extracellular fluid volume differences<br>between the arms to aid in the clinical<br>assessment of unilateral lymphedema of<br>the arm women. This device is not<br>intended to diagnose or predict<br>lymphedema of and extremity. |
| | The device is only indicated for patients<br>who will have or who have had lymph<br>nodes, from the axillary and pelvic<br>regions, either removed, damaged or<br>irradiated. | The device is only indicated for patients<br>who will have or who have had lymph<br>nodes, from the axillary and pelvic<br>regions, either removed, damaged or<br>irradiated. | Lymphedema Analysis PC Software - an<br>optional PC software package that is<br>intended to be used only with the<br>ImpediMed L-Dex U400 device for<br>uploading data on to the PC from the L-<br>Dex U400, processing and analyzing of<br>bioimpedance measurements. |
| | Lymphedema Analysis PC Software - an<br>optional PC software package that is<br>intended to be used only with the<br>ImpediMed L-Dex U400 device for<br>uploading data on to the PC from the L-<br>Dex U400, processing and analyzing of<br>bioimpedance measurements. | This device is not intended to diagnose or<br>predict lymphedema of and extremity. | |
| | | Lymphedema Analysis PC Software - an<br>optional PC software package that is<br>intended to be used only with the<br>ImpediMed L-Dex U400 device for<br>uploading data on to the PC from the L-<br>Dex U400, processing and analyzing of<br>bioimpedance measurements. | |
33
:
035
{3}------------------------------------------------
| | 2<br>processil |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|
| Aland Book Children Aller | |
| | |
| 111 1 70 7 7 0 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 | |
| | | Dex U400, processing and analyzing of bioimpedance measurements. | |
|------------|---------------------------------------------------------------------------------|--------------------------------------------------------------------------------|--------------------------------------------------------------------------------|
| Principle | Bioelectrical impedance in the range of 4<br>kHz to 1000 kHz (256 frequencies). | Bioelectrical impedance in the range of 4<br>kHz to 1000 kHz (256 frequencies) | Bioelectrical impedance in the range of 4<br>kHz to 1000 kHz (256 frequencies) |
| Dimensions | L=190mm, W=130mm, D=110mm | L=190mm, W=130mm, D=110mm | L=190mm, W=130mm, D=110mm |
| Weight | 1 kg / 2.2 lbs (including battery) | 1 kg / 2.2 lbs (including battery) | 1 kg / 2.2 lbs (including battery) |
036
.
1. September 19.
and the comments of the comments of the comments of the comments of
1. The state of the state of the states of the states of the states of the states of the states of the states of the states of the states of the states of the states of the s
{4}------------------------------------------------
Image /page/4/Picture/1 description: The image shows the logo for the U.S. Department of Health & Human Services. The logo features a stylized eagle with three lines representing its body and wings. The words "DEPARTMENT OF HEALTH & HUMAN SERVICES - USA" are arranged in a circular pattern around the eagle.
#### Public Health Service
Food and Drug Administration 10903 New Hampshire Avenue Document Control Center - WO66-G609 Silver Spring, MD 20993-0002
#### May 31, 2013
ImpediMed Limited % John J. Smith, M.D., J.D. Regulatory Counsel Hogan Lovells US LLP 555 13th Street, NW WASHINGTON DC 20004
Re: K130338
Trade/Device Name: L-Dex® U400 Regulation Number: 21 CFR§ 870.2770 Regulation Name: Impedance plethysmograph Regulatory Class: II Product Code: OBH Dated: May 7, 2013 Received: May 7, 2013
Dear Dr. Smith:
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-todevices 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.
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.
{5}------------------------------------------------
Page 2 - John J. Smith, M.D., J.D.
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 device-related 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 go to http://www.fda.gov/AboutFDA/CentersOffices/CDRH/CDRHOffices/ucm 1 1 5809.htm for the Center for Devices and Radiological Health's (CDRH's) Office of Compliance. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21CFR 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 Small Manufacturers, International and Consumer Assistance 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 yours,
for_
Image /page/5/Picture/7 description: The image shows the name "Herbert P. Lerner -S" in a bold, sans-serif font. The letters are black against a white background, creating a high contrast. The letters "P" and "L" are stylized with a decorative pattern.
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
{6}------------------------------------------------
#### Indications for Use Statement
K130338 510(k) Number (if known):
Device Name: L-Dex® U400
Indications for Use:
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.
Lymphedema Analysis PC Software - an optional PC software package that is intended to be used only with the ImpediMed L-Dex U400 device for uploading data on to the PC from the L-Dex U400, processing and analyzing of bioimpedance measurements.
| Prescription Use | X |
|-----------------------------|---|
| (Part 21 CFR 801 Subpart D) | |
AND/OR
| Over-The-Counter Use | |
|------------------------|--|
| (21 CFR 801 Subpart C) | |
(PLEASE DO NOT WRITE BELOW THIS LINE-CONTINUE ON ANOTHER PAGE OF NEEDED)
Concurrence of CDRH, Office of Device Evaluation (ODE)
# Herbert | Polygrner -S
(Division Sign-Off) Division of Reproductive, Gastro-Renal, and Urological Devices K130338 510(k) Number
Page 1 of 1
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.