IMPEDIMED EXTRA CELLULAR FLUID ANALYSIS, MODEL L-DEX U400
Applicant
Impedimed Pty , Ltd.
Product Code
OBH · Cardiovascular
Decision Date
Oct 3, 2008
Decision
SESK
Submission Type
Traditional
Regulation
21 CFR 870.2770
Device Class
Class 2
Indications for Use
The L-Dex U400: A bioelectrical impedance analyzer/monitor utilizing impedance ratios that supports the measurement of extra cellular fluid volume differences between the arms to aid in the clinical assessment of unilateral lymphedema of the arm in women. This device is not intended to diagnose or predict lymphedema of an extremity. Lymphedema Analysis PC Software – an optional PC software package that is intended to be used only with the ImpediMed L-Dex U400 analyzer/monitor 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 multi-frequency bioelectrical impedance analyzer. It inputs current, voltage, and phase angle measurements via tetra-polar electrodes spanning the arms. A 200uA RMS constant current (4kHz to 1000kHz) is applied; voltage drop is measured to calculate impedance, resistance, and reactance. These values are processed using bioelectrical impedance basics and anthropometric parameters to estimate extra cellular fluid (ECF) ratios (L-Dex index). The device is used in clinical settings to assess unilateral lymphedema trends in women. Output is provided via an optional PC software package for data upload and analysis. Clinicians use these estimates as an alternative to circumferential measurements or water immersion methods to monitor fluid volume differences between arms, aiding in clinical assessment.
Clinical Evidence
No clinical data provided. The device relies on bioelectrical impedance basics, mathematical models, and anthropometric parameters derived from peer-reviewed published journal articles to convert measured impedance to ECF estimates.
Technological Characteristics
Battery-powered, multi-frequency bioelectrical impedance analyzer. Operates in tetra-polar mode. Frequency range: 4kHz to 1000kHz. Current: 200uA RMS. Measures current, voltage, phase angle; calculates impedance, resistance, and reactance. Includes optional PC software for data processing. Calibration circuit accessory provided for quality assurance.
Indications for Use
Indicated for women to aid in the clinical assessment of unilateral lymphedema of the arm by measuring extra cellular fluid volume differences between arms. Not intended to diagnose or predict lymphedema.
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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KC80825
PAGE 1 OF 4
ImpediMed
# OCT - 3 2008
### ImpediMed Limited
ABN 65 089 705 144
Unit l 50 Parker Court Pinkenba Qld 4008
+61 (0)7 3860 3700 Tel: Freecall: | 800 638 477 Fax: +61 (0)7 3260 1225
Email: enquiries@impedimed.com www.impedimed.com
# 510 (k) Summary ImpediMed L-Dex U400 BIS Extra Cellular Fluid Analysis
## APPLICANT INFORMATION
| Company Name and address: | ImpediMed Limited<br>Unit1<br>50 Parker Court<br>Pinkenba, QLD - 4008 |
|--------------------------------|------------------------------------------------------------------------------------------------------------------------------------------|
| Contact Name and numbers: | Mr Phillip Auckland<br>Chief Operations Officer<br>Phone: (+61) 7 3860 3700<br>Fax: (+61) 7 3260 1225<br>E-mail: pauckland@impedimed.com |
| Date of summary prepared: | August 26, 2008 |
| DEVICE IDENTIFICATION | |
| Trade/Proprietary name: | L-Dex U400 BIS Extra Cellular Fluid Analysis |
| Classification name: | Impedance Plethysmograph |
| Regulation number/CFR section: | 21 CFR 870.2770 |
| Product code: | DSB |
| Classification panel: | Cardiovascular |
| Device class: | Class II 000013R |
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# ImpediMed Limited
ABN 65 089 705 144
Unit l 50 Parker Court Pinkenba Qld 4008
+61 (0)7 3860 3700 Tel: Freecall: | 800 638 477 Fax: +61 (0)7 3260 1225
Email: enquiries@impedimed.com www.impedimed.com
## PREDICATED DEVICE
| Company: | ImpediMed Limited |
|-----------------------|---------------------------------------|
| Device name: | Imp XCA Extra Cellular Fluid Analysis |
| 510 (K) number: | K050415 |
| Product code: | DSB |
| Classification panel: | Cardiovascular |
| Device class: | Class II |
| PREDICATED DEVICE | |
| Company: | ImpediMed Limited |
| Device name: | Imp SFB7 Body Composition Analyzer |
| 510 (K) number: | K052319 |
| Product code: | DSB |
| Classification panel: | Cardiovascular |
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#### ImpediMed Limited
ABN 65 089 705 144
Unit I 50 Parker Court Pinkenba Qld 4008
Tel: Freecall: 1 800 638 477 +61 (0)7 3260 1225 Fax:
Email: enquiries@impedimed.com www.impedimed.com
#### INTENDED USE / INDICATIONS FOR USE
The L-Dex U400: A bioelectrical impedance analyzer/monitor utilizing impedance ratios that supports the measurement of extra cellular fluid volume differences between the arms to aid in the clinical assessment of unilateral lymphedema of the arm in women. This device is not intended to diagnose or predict lymphedema of an extremity.
Lymphedema Analysis PC Software – an optional PC software package that is intended to be used only with the ImpediMed L-Dex U400 analyzer/monitor for uploading data on to the PC from the L-Dex U400. processing and analyzing of bioimpedance measurements.
#### DEVICE DESCRIPTION
The L-Dex U400 is a multi frequency bioelectrical impedance analyser. The device accurately measures current, voltage and phase angle, and calculates impedance, resistance and reactance as with the XCA. These measurements and calculations are used to estimate extra cellular fluid (ECF) allowing for the assessment of the development of unilateral Lymphedema of the arms.
#### TECHNOLOGICAL CHARECTERISTICS
The ImpediMed L-Dex U400 Extra Cellular Fluid Analyzer, like the SFB7, is a battery powered, accurate, multi frequency, bioelectrical impedance analysis instrument operating in tetra-polar mode. The device accurately measures current, voltage and phase angle, and calculates impedance, resistance and reactance.
Bioelectrical impedance analysis measures the impedance or opposition to the flow of an electric current through the body fluids contained mainly in the lean and fat tissue. Impedance is low in lean tissue, where intracellular fluid and electrolytes are primarily contained, but high in fat tissue. Impedance is thus related to total fluid volume. The tissue and organs of the body are composed of cells surrounded by a cell membrane separates fluid inside cells called intracellular
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#### ImpediMed Limited
ABN 65 089 705 144
Unit l 50 Parker Court Pinkenba Qld 4008
+61 (0)7 3860 3700 Tel: Freecall: 1 800 638 477 +61 (0)7 3260 1225 Fax:
Email: enquiries@impedimed.com www.impedimed.com
fluid (ICF) from that surrounding the cells termed as extra cellular fluid (ECF) that act as conductors to the flow of current through the body.
However, the cell membrane and tissue interfaces because they are 'imperfect capacitors' act as a barrier to penetration of current at low frequencies. Thus the total impedance and phase angle of alternating current flow will be frequency dependent.
The ImpediMed L-Dex U400 is specifically designed for segmental bioelectrical impedance analysis to measure the ECF of the arms in which a small alternating constant current of 200uA RMS at a frequency of 4kHz+ 100Hz to 1000 kHz+ is passed between two current electrodes spanning the body. The voltace drop measured between a second pair of voltage-sensing electrodes is used to calculate the impedance value. The performance of the device may be checked with the aid of a calibration circuit (supplies as an accessory) for quality assurance or servicing purposes.
Bioelectrical impedance basics, simple mathematics, bioelectrical and anthropometric parameters from peer reviewed published iournal articles are used to convert measured impedance to a corresponding estimate of extra cellular fluid ratio (extra cellular fluid index or lymphedema index referred to as L-Dex), and differences between the arms. These estimates can be used as alternatives to the current circumferential measurements and water immersion methods, to indicate trends toward the potential development of Lymphedema.
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Food and Drug Administration 9200 Corporate Boulevard Rockville MD 20850
Mr. Phillip Auckland Chief Operations Officer ImpediMed Limited Unit 1, 50 Parker Court Pinkenba Queensland 4008 AUSTRALIA
OCT - 3 2008
Re: K080825
Trade/Device Name: ImpediMed L-Dex U400 and optional Lymphedema Analysis PC Software Regulation Number: 21 CFR §870.2770 Regulation Name: Impedance plethysmograph Regulatory Class: II Product Code: OBH Dated: August 26, 2008 Received: August 29, 2008
Dear Mr. Auckland:
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 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). You may, therefore, market the device, subject to the general controls provisions of the Act. However, you are responsible to determine that the medical devices you use as components in the kit have either been determined as substantially equivalent under the premarket notification process (Section 510(k) of the act), or were legally on the market prior to May 28, 1976, the enactment date of the Medical Device Amendments. Please note: If you purchase your device components in bulk (i.e., unfinished) and further process (e.g., sterilize) you must submit a new 510(k) before including these components in your kit. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, and labeling, and prohibitions against misbranding and adulteration.
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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#### Page 2 -- Mr. Phillip Auckland
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); 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.
This letter will allow you to begin marketing your device as described in your Section 510(k) premarket notification. The FDA finding of substantial equivalence of your device to a legally marketed predicate device results in a classification for your device and thus, permits your device to proceed to the market.
If you desire specific advice for your device on the labeling regulation, please contact the Office of Compliance at (240) 276-0115. Also, please note the regulation entitled, "Misbranding by reference to premarket notification'' (21 CFR Part 807.97). 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 (240) 276-3150, or at its Internet address http://www.fda.gov/cdrh.dsmamain.html.
Sincerely yours,
Hubert Leiner
Joyce M. Whang, Ph.D. Acting Director, Division of Reproductive, Abdominal, and Radiological Devices Office of Device Evaluation Center for Devices and Radiological Health
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# Indications for Use
#### 510(k) Number (if known): K080825
#### Device Name: ImpediMed L-Dex U400
Indications for Use:
The L-Dex U400: A bioelectrical impedance analyzer/monitor utilizing impedance ratios that supports the measurement of extra cellular fluid volume differences between the arms to aid in the clinical assessment of unilateral lymphedema of the arm in women. This device is not intended to diagnose or predict lymphedema of an extremity.
Lymphedema Analysis PC Software - an optional PC software package that is intended to be used only with the ImpediMed L-Dex U400 analyzer/monitor for uploading data on to the PC from the L-Dex U400, processing and analyzing of bioimpedance measurements.
Prescription Use (Part 21 CFR 801 Subpart D)
Over-The-Counter Use AND/OR (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)
Huld Leuer
(Division Sign-Off)
Divisi: : )f Reproductive, Abdomin and Rachological Devices 510(k) Number
K806625
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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.