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The VL40xx is a Non-Invasive diagnostic system designed to detect peripheral vascular pathology in adults. In all cases the intended use is for spot checking and attended use by trained medical professionals in a hospital or medical facility by the order of a medical doctor.

The VL40xx is not intended to replace other means of evaluating vital patient physiological processes, is not intended to be used in fetal applications, and is not intended to be used inside the sterile field.

The VL40xx is a family of products designed for non-invasive peripheral vascular diagnostic systems. The VL40 indicates the family of products that are all made from the same parts with the only differences being that some parts are not installed or some features are not enabled. The "xx" will be used to indicate the family of products. Options of what Doppler or PPG probes are installed do not qualify for a specific model number because there is no physical change to the device to add them. Different air channels require a model number because the valves require a physical change to the device that can only be done at the factory. Specifically the following models are used.

• . Model 4000: full system, twelve channel air
• Model 4010: full system, two channel air portable .
• Model 4030: ABI (Ankle Brachial Index), six channel air .

The base unit has the same main printed circuit board (PCB), battery, speaker, software, and power supply.

Adding the PPG option requires installing a PCB module to the main PCB and attaching the PPG sensors to the outside of the case.

Adding the Doppler requires attaching the desired frequency probe (4 or 8 MHz) to the case. All Doppler frequency probes use the same PCB logic. This means that any probe frequency can be added without any changes to the main PCB or the connectors. The universal Doppler probe is possible because all the Doppler electronics are in the probe. The device PCB for the Doppler only has the logic to turn on the probe and read the data. The Doppler probe has all the electronics to control the IQ signal separation and power output of the probe.

Adding the temperature reading requires purchasing a cleared FDA IR temperature probe from a 3rd party (example Exergen model TAT 5000, K011291). The IR device is a complete standalone product with its own FDA clearance. The VL40xx simply provides a method in software for the operator to record the temperature samples in a table for convenience of reporting. The temperature tests protocols do not care about the absolute temperature readings but do care about the differential readings. What is important is the temperature difference of before and after readings.

For the above features there are no changes to the case and the changes can be made at any time.

The following features require changes to the back panel of the case to support the number of air hoses. The number of air hoses installed is 2, 6, or 12. Internally only the required valves, pressure sensors, and pumps will be installed. Adding air hoses later would require a new case and the appropriate valves, pressure sensors, and pumps to be added. It is much easier to install all the valves and manage the air connectors by choosing what air hoses are attached externally. Unless weight / portability are an issue the easiest solution will always be to choose the 12 air hose system and manage the external air hoses. The external air hoses can be changed at any time to create a system that has 2-12 air hoses as needed. The VL4000 is the model with all air hoses enabled internally.

The air hoses are color coded to help the user attach them to the correct blood pressure cuff. Each air hose has a Red for Right and Lemon for Left code in addition to another color (white, black. orange, yellow, blue, and green) to help identify the location of the software always displays the color of the side (Red or Lemon) and the color of the location that it intends to use. The system has no way to determine that the user connects the air hose to the correct cuff at the correct location.

The software for all models is exactly the same. The software automatically detects what features are installed. All models have the following software features: patient history, comments, storage, printing, print preview, configuration, and online help. Optional software features include Modality Work List (MWL), exporting of data using DICOM Images / Structured Reporting, email, native PDF, long term data storage, data mirroring, and online support.

The VL4030 ABI system will have all tests disabled in software except for the ABI specific tests.

One of the main measurements of the system is segmental systolic blood pressures. In general, the measurement is conducted by applying an appropriately sized cuff to the measured segment, obtaining a reference PPG or a Doppler signal in a location distal to the cuff placement, and then inflating the cuff to such a pressure that will occlude the blood vessels and prevent blood flow distal to the cuff location, which will result in disappearance of the reference signal. Then, a slow cuff deflation begins, and the instantaneous cuff pressure at which the reference signal reappears is typically defined as the segmental systolic blood pressure. While the software automatically places a cursor at the time location which is suspected as being the systolic pressure, it is the total responsibility of the system operator and the medical staff to modify the cursor location according to their medical training, and define the correct segmental pressure.

Based on the segmental pressures, the pressure indices are calculated, as the ratio between the systolic segmental pressure, and the higher of the 2 brachial systolic pressures that does not exceed a noncompressible limit (usually 240 mmHg). The ABI index is a commonly used index, which is a specific case of the above, calculated as the systolic right or left ankle pressure, divided by the hight or left brachial systolic pressure.

The other main measurement of the system is recording a wave that represents the flow of blood for each heartbeat. The three main modalities for this are the Doppler, PPG, and PVR wave forms. All three of these modalities produce a wave form that has a systolic up stroke, a diastolic down stroke, a pause, and a repeat. Researchers have shown that the shape of these waveforms is a great indicator of disease and that the actual measurement of the wave is not as important.

The system has a wireless remote control. Everything that the remote can do can also be done with the keyboard. The advantage of the remote is that it provides the most common functions needed to perform the measurement without requiring the operator to reach for the keyboard.

If the IR remote is not available then the user will access the VL40xx using a directly wired keyboard, mouse, or touchscreen.

The scientific principal of CW Doppler in very high level terms is as follows. A crystal is cut in half. One half of the crystal has a 4 or 8 MHz sine wave applied. When the acoustic output of the crystal is focused into human tissue it will bounce back and be absorbed by the remaining crystal. Any Doppler effect caused by moving blood can be detected in the phase shift when the transmitted signal is compared with the echoed signal. The phase shift for blood in humans is usually less than 6 kHz and therefore makes for a nice audio signal that can easily be heard. Most modern CW Doppler systems will use IQ modulation and FFT to detect the spectral of the audio signal returned. Tracing the envelope of the spectral will provide the familiar heart beat trace. The CW Doppler can measure the velocity of blood in a specific artery.

The scientific principal of PPG in very high level terms is as follows. An Infra-Red pulse is provided by an LED and applied to the skin. The blood and tissue will absorb and reflect the IR signal. The amount of blood in the capillaries will determine how much IR signal is absorbed or reflected. An LED sensor is applied that measures the reflected IR signal. Displaying the LED sensor output will provide the familiar heart beat trace. The PPG can measure the change in blood flow in the skin.

The scientific principal of VPR in very high level terms is as follows. A cuff is placed around an arm or leg and inflated to 60 mmHg. The higher the pressure without occluding the blood flow (below systolic blood pressure) will produce the best pressure change in the cuff for each heartbeat will cause a pressure change in the cuff ranging from 0.01 – 0.5 mmHg. Displaying the pressure sensor output will provide the familiar heart beat trace. The VPR can measure the change in blood flow for a network of arteries.

The speaker is located on the front of the VL40xx and all other connectors (Doppler, PPG, VPR, USB, power supply, and status LEDs) are on the back.

The provided document, K131860, is a 510(k) Summary for the VascuLab VL40xx, VL4000, VL4010, VL4030 non-invasive peripheral vascular diagnostic systems.

It is important to note that this document describes a traditional medical device (a piece of hardware with associated software), not an AI/ML-driven device. Therefore, many of the typical acceptance criteria and study designs associated with AI/ML devices (such as ground truth establishment with experts, MRMC studies, or standalone algorithm performance) are not applicable or described in this submission.

The acceptance criteria discussed primarily relate to regulatory compliance, general safety, and functional equivalence to a predicate device.

Acceptance Criteria and Reported Device Performance

Given that this is not an AI/ML device, the "acceptance criteria" are not framed in terms of diagnostic performance metrics (e.g., sensitivity, specificity, AUC) against a ground truth dataset, but rather in terms of engineering, safety, and functional requirements.

Study Details (Applicable to Non-AI/ML Devices)

1. Sample size used for the test set and the data provenance (e.g. country of origin of the data, retrospective or prospective)

   • The document describes non-clinical testing primarily focused on engineering validation, safety, and functional performance rather than diagnostic accuracy on patient data.
   • There is no mention of a "test set" of patient data for diagnostic performance evaluation or data provenance (country of origin, retrospective/prospective).
   • The testing mentioned includes Bio-Compatibility, Electrical Safety, Mechanical Safety, Acoustic Output, EMC emissions and immunity, and internal unit/verification/performance/validation testing. These typically involve laboratory setups, phantoms, or specific test equipment, not patient data in the context of diagnostic accuracy.

2. Number of experts used to establish the ground truth for the test set and the qualifications of those experts (e.g. radiologist with 10 years of experience)

   • Not applicable as there is no diagnostic "test set" or ground truth based on expert consensus described for evaluating diagnostic performance. The device is a measurement tool, where the operator interprets the data.

3. Adjudication method (e.g. 2+1, 3+1, none) for the test set

   • Not applicable as there is no diagnostic "test set" requiring adjudication.

4. If a multi reader multi case (MRMC) comparative effectiveness study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

   • Not applicable. This is not an AI/ML device, and no MRMC study is described. The device provides measurements and waveforms which are then interpreted by a "trained medical professional."

5. If a standalone (i.e. algorithm only without human-in-the-loop performance) was done

   • Not applicable. This is not an AI/ML device relying on an algorithm to make diagnostic interpretations. It's a measurement device.

6. The type of ground truth used (expert consensus, pathology, outcomes data, etc)

   • For the safety and functional testing described, the "ground truth" would be established engineering specifications, recognized standards, and physical laws (e.g., accuracy of pressure readings against calibrated instruments, acoustic output measurements according to standards). There is no "ground truth" in the diagnostic sense from patient data.

7. The sample size for the training set

   • Not applicable. This is not an AI/ML device that requires a training set.

8. How the ground truth for the training set was established

   • Not applicable.

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