The QFlow™ 500 is intended for extravascular monitoring of microcirculation blood flow in buried tissues. Examples of this application included (but are not limited to) 1) the monitoring of buried muscle or esophaqus following free muscle transfer or esophageal reconstruction, 2) monitoring soft tissue microcirculation following reconstructive surgery, such as oral and facial reconstruction, 3) monitoring cerebral blood flow during and following neurosurgery for head trauma.
Device Story
QFlow™ 500 is a perfusion monitoring system consisting of a thermal diffusion probe and a monitor. The probe, containing two thermistors at its distal tip, is inserted into tissue to measure thermal conductivity and real-time perfusion via thermal energy dissipation. The monitor controls the thermistors, processes the thermal data, and displays perfusion, temperature, and thermal conductivity values numerically and graphically. Used in ICU, OR, or patient rooms by clinicians; not for patient transport. The system stores up to 10 days of data, supports printing, and allows data export to external computers. The probe includes an EEPROM for calibration data, usage time tracking, and verification. By providing continuous microcirculation monitoring, the device assists clinicians in assessing tissue viability post-reconstruction or monitoring cerebral blood flow, potentially enabling early intervention for compromised tissue.
Clinical Evidence
Bench testing, animal studies, and biocompatibility testing were performed. Electrical safety and electromagnetic compatibility were verified against IEC 60601-1, IEC 60601-1-2, EN 55011, and UL 2601. Probe integrity and sterility were evaluated per ISO 10555 and ISO 10993.
Technological Characteristics
System consists of a thermal diffusion probe (<1 mm diameter, 60-120 cm length) and a monitor. Probe contains two thermistors and an EEPROM for calibration/verification. Sensing principle: thermal energy dissipation to measure tissue thermal conductivity and perfusion. Electrical safety: IEC 60601-1, UL 2601. EMC: IEC 60601-1-2, EN 55011. Biocompatibility: ISO 10993. Connectivity: data export to external computer. Sterilization: ISO 10555 compliant.
Indications for Use
Indicated for extravascular monitoring of microcirculation blood flow in buried tissues, including post-surgical monitoring of free muscle transfers, esophageal reconstruction, oral/facial soft tissue reconstruction, and cerebral blood flow monitoring during/following neurosurgery for head trauma.
Regulatory Classification
Identification
A cardiovascular blood flowmeter is a device that is connected to a flow transducer that energizes the transducer and processes and displays the blood flow signal.
Predicate Devices
Transonic Systems ALF 21 Advanced Laser Flowmeter (K903633)
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C013376
## MAY 0 8 2002
# 510K Summary of Safety and Effectiveness
- Sponsor Name 1.
Hemedex, Inc. 222 Third Street, Suite T123 Cambridge, MA 02142 USA
- 2. Device Name QFlow™ 500 Perfusion Monitoring System
- 3. Identification of Predicate or Legally Marketed Device QFlow™ 500 is substantially equivalent to the following predicate devices:
- Transonic Systems ALF 21 Advanced Laser Flowmeter cleared under . K903633.
- TSI LaserFlo™ Blood Perfusion Monitor cleared under K896515. . (Vasamedics purchased TSI in 1990)
- Vasomedics Laserflo Blood Perfusion Probes (K951832, K962700, ● K961368 )
- Device Description 4.
The QFlow™ 500 has application where real-time determination of any tissue perfusion is desired, whether it is for measurement or monitoring utilization. The system may be used in the Intensive Care Unit, Operating Room, Radiology Suite or in a standard patient care room. However, the system is not designed for use during patient transport.
The QFlow™ 500 consists of a thermal diffusion probe and a monitor.
The QFlow™ 500 Perfusion System Probe thermally interacts with tissue. It contains two thermistors embedded at the distal tip of the probe. It is available in a range of lengths from 60 cm to 120 cm and less than 1 mm in diameter. The probe contains an EEPROM for the storage of probespecific calibration data, data on the cumulative time the probe has been in use, and a verification key to insure the origin of the probe. The probe connector physically connects the probe to the umbilical cord which connects to the monitor.
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The QFlow™ 500 Monitor controls the thermistors in the Probe.
Perfusion data are displayed on the monitor. The current perfusion value, temperature and thermal conductivity are be displayed in numeric form. The data are also displayed in the form of a graph as a function of time.
The monitor is capable of storing data for up to 10 days. All of this stored data may be reviewed by the user at any time during this period. Printing of data is also an option from the monitor. There is also the capability of uploading data from the monitor to an external computer for further analysis.
#### 5. Intended Use
The QFlow™ 500 is intended for extravascular monitoring of microcirculation blood flow in buried tissues. Examples of this application included (but are not limited to) 1) the monitoring of buried muscle or esophaqus following free muscle transfer or esophageal reconstruction, 2) monitoring soft tissue microcirculation following reconstructive surgery, such as oral and facial reconstruction, 3) monitoring cerebral blood flow during and following neurosurgery for head trauma.
#### 6. Comparison of Technological Characteristics
All of the devices are indicated to provide blood perfusion measurements in any perfused tissue where blood flow information is desired. However, the manner in which the measurements are made is different.
The QFlow™ 500 uses thermal energy dissipated in a thermistor to measure the thermal conductivity of the tissue and a real-time measurement of tissue perfusion. The predicate devices use laser light energy which is scattered by reflective components within the tissue and is reflected back via a receiving fiber optic probe. This provides a measurement of blood flow within the tissue.
The QFlow 500 is substantially equivalent to the predicate devices listed, which provide the same or similar functions, as well as design and technological characteristics. The intended use, statement of indications, and technological characteristics for the QFlow 500 support the concept of substantial equivalence.
#### 7 Performance Testing
Bench testing, animal studies and biocompatibility testing was performed on the QFlow 500.
The QFlow™ 500 is tested for compliance with the following standards for electrical safety, thermal safety, electromagnetic compatibility, electromaqnetic emissions and probe integrity:
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IEC 60601-1 (1988) 2nd Edition, + A1: 1991 + A2: 1995 Medical Electrical Equipment – General Requirements for Safety
IEC60601-1-2: 1993 Medical Electrical Equipment – Collateral Standard Electromagnetic Compatibility
EN 55011 Limits and Methods of Measurement of Radio Disturbance characteristics of Industrial, Scientific and Medical (ISM) Radio-Frequency Equipment.
UL2601, UL standard for Safety, Medical Electrical Equipment, Part 1: General Requirements for Safety, First Edition
ISO 10555 Sterile, single-use intravascular catheters Part 1: General Requirements
Biological evaluation of medical devices ISO 10993: 1997 Part 1: Guidance on selection of tests.
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### DEPARTMENT OF HEALTH & HUMAN SERVICES
Food and Drug Administration 9200 Corporate Boulevard Rockville MD 20850
MAY 0 8 2002
Hemedex, Inc. c/o Ms. Debbie Iampietro QRC Consulting 7 Tiffany Trail Hopkinton, MA 01748
Re: K013376
Trade Name: QFlow 500 Perfusion Monitoring System Regulation Number: 21 CFR 870.2100 Regulation Name: Blood Flow Monitor Regulatory Class: Class II (two) Product Code: DPW Dated: February 11, 2002 Received: February 12, 2002
Dear Ms. Iampietro:
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.
If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to such 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 - Ms. Debbie Iampietro
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 our labeling regulation (21 CFR Part 801 and additionally 21 CFR Part 809.10 for in vitro diagnostic devices), please contact the Office of Compliance at (301) 594-4646. Additionally, for questions on the promotion and advertising of your device, please contact the Office of Compliance at (301) 594-4639. Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21CFR Part 807.97). Other general information on your responsibilities under the Act may be obtained from the Division of Small Manufacturers, International and Consumer Assistance at its toll-free number (800) 638-2041 or (301) 443-6597 or at its Internet address http://www.fda.gov/cdrh/dsma/dsmamain.html
Sincerely yours,
Dough Teth
Donna-Bea Tillman, Ph.D. Acting Director Division of Cardiovascular and Respiratory Devices Office of Device Evaluation Center for Devices and Radiological Health
Enclosure
{5}------------------------------------------------
Hemedex. Inc QFlow™ 500 Perfusion Monitoring System Premarket Notification
510(k) Number (if known): KO13376
Device Name: QFlow 500 Perfusion Monitoring System
Indications For Use:
The QFlow™ 500 is intended for extravascular monitoring of microcirculation blood flow in buried tissues. Example of this application included (but are not limited to) 1) the monitoring of buried muscle or esophagus following free muscle transfer or esophageal reconstruction, 2) monitoring soft tissue microcirculation following reconstructive surgery, such as oral and facial reconstruction, 3) monitoring cerebral blood flow during and following neurosurgery for head trauma.
(PLEASE DO NOT WRITE BELOW THIS LINE. CONTINUE ON ANOTHER PAGE IF NEEDED)
Concurrence of CDRH, Office of Device Evaluation (ODE)
Prescription Use
(Per 21 CFR 801.109)
OR
Over-The-Counter Use
Division of Cardiovascular & Respiratory Devices
510(k) Number K03376
000 . 0
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Learn the FDA Browser
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.