Patent Description:
The anastomosis of the free flap tissue to the native tissue is typically done using microvascular techniques, including under microscopic visualization. In previous years, several surgical instruments and techniques have been developed to aid in anastomosis. One known system for creating an anastomosis is an anastomosis coupler, described in <CIT>. This anastomotic coupler is a surgical instrument that allows a surgeon to more easily and effectively join together two blood vessel ends. The coupler involves the use of two fastener portions, in the shape of rings, upon which are secured respective sections of the vessel to be attached. Each fastener portion is also provided with a series of pins, and corresponding holes for receiving those pins, in order to close and connect the portions, and in turn the vessel, together (See <FIG>, <FIG>).

While free flap surgeries have a history of success, highly undesirable consequences of a flap failure still remain a possibility. One of the main causes of flap failure is a lack of blood being supplied to the flap tissue after the free flap is reattached at the recipient site. Things that commonly disturb circulation in a flap include vascular occlusion, hemorrhage, or infection. When not enough blood is supplied to the flap tissue, tissue necrosis results. However, if it can be recognized early enough that the flap is not receiving adequate circulation, it may be saved, or salvaged. The window of time for salvaging the flap after a lack of blood flow is recognized is very small. It is therefore critical that any lack of blood flow in a transferred flap be quickly recognized.

Handheld Doppler probes, which are typically permanently positioned on the distal tip of a pen-like device instead of being placed or left within the body, are helpful in blood flow monitoring, but they suffer from several drawbacks. One drawback with handheld probes is their inability to be reliably positioned about a vessel.

It is of great importance after microvascular surgery to monitor the region of the surgery in order to make sure that the blood flow is maintained at the desired level and that no problems, such as thromboses have occurred. Should thrombosis occur, the transferred tissue would die. Other indirect means of monitoring the functioning of blood flow through blood vessels, which have been subjected to microvascular surgery, are also often inadequate. For example, surface temperature measurements, transcutaneous PO<NUM> monitoring, photo plethysmography and laser Doppler flow meters have been employed. However, these approaches generally require an accessible exposed portion of the flap. Additionally, buried free tissue transfers and intraoral flaps cannot be monitored effectively by these methods.

Devices and systems according to the preambles of claims <NUM> and <NUM> are known from <CIT>.

The present disclosure provides improved vascular monitoring systems, devices and methods to improve the accessibility, detection and/or reliability of detecting blood flow to confirm vessel patency at an anastomotic site.

In one example embodiment, a Doppler blood flow monitoring device according to claim <NUM> is provided.

In another example embodiment, a Doppler blood flow monitoring system according to claim <NUM> is provided.

In another example embodiment, a remote monitoring system according to claim <NUM> is provided.

It is accordingly an advantage of the present disclosure to improve accessibility of blood flow data.

It is another advantage of the present disclosure to improve the detection of blood flow to confirm vessel patency.

It is another advantage of the present disclosure to provide remote monitoring of blood flow at an anastomotic site.

It is a further advantage of the present disclosure to reduce background noise from audio signals representing blood flow within a vessel.

It is yet a further advantage of the present disclosure to reduce the occurrence of free flap failure and serious adverse events due to insufficient blood flow in a free flap.

It is still another advantage of the present disclosure to provide a system, device and/or method for early detection of insufficient blood flow or circulation in a free flap.

Additional features and advantages of the disclosed vascular monitoring system, device and method are described in, and will be apparent from, the following Detailed Description and the Figures. Also, any particular embodiment does not have to have all of the advantages listed herein. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter.

In this specification the following non-SI unit is used, which may be converted to the respective SI unit according to the following conversion table:.

As discussed above, vascular monitoring system, device and method are provided to improve the accessibility, detection and/or reliability of detecting blood flow to confirm vessel patency at an anastomotic site. While free flap surgeries have a history of success, highly undesirable consequences of a flap failure still remain a possibility. One of the main causes of flap failure is a lack of blood being supplied to the flap tissue after the free flap is reattached at the recipient site. Things that commonly disturb circulation in a flap include vascular occlusion, hemorrhage, or infection. When not enough blood is supplied to the flap tissue, tissue necrosis results. However, the vascular monitor system, device and methods disclosed herein advantageously enable early detection of insufficient blood flow or circulation in a free flap so that it may be saved, or salvaged before tissue necrosis.

The above vascular monitoring system, device and methods may be used to monitor blood flow at the anastomotic site to confirm vessel patency of a surgical procedure, such as a free flap transfer micro vascular reconstruction. The above system, device and methods may be used in various environments such as a hospital operating room or a post-anesthesia care unit to detect blood flow and confirm vessel patency (either on-site or remotely) both intra-operatively and post-operatively. Free flap transfer may be used to recreate body parts from surgery due to cancer and injury using the patient's own tissue. Examples include breast reconstruction, tongue reconstruction, jaw and cheek reconstruction, hand and foot reconstruction after trauma injuries, etc. Typically, the microvascular anastomosis is the critical point of the surgery that determines the success of the flap. By providing monitoring capabilities of blood flow at an anastomotic site and increasing the access to these monitoring capabilities (e.g., remote access via a monitoring application on a user device such as a smart phone), the system, devices and methods disclosed herein allow early detection of low blood flow or lack of blood flow within the flap tissue thereby enabling a medical practitioner (e.g., a surgeon) to take corrective action before necrosis sets in and the free flap becomes unusable.

<FIG> illustrates a schematic view of a flow monitor system 100A and <FIG> illustrates a perspective view of a flow monitor system 100B (both of which may be referred to generally as flow monitor system <NUM>). Flow monitor system <NUM> may include multi-component probe systems 102a and 102b attached to a monitor <NUM> via external leads 110a and 110b. For example, probe system 102a may be attached to "channel A" of monitor <NUM> via external lead 110a while probe system 102b is attached to "channel B" of monitor <NUM> via external lead 110b. Specifically, monitor <NUM> may provide monitoring for at least two anastomosis sites by having at least two Doppler probe inputs or connector ports (illustrated in <FIG>) and is capable of user selectable monitoring of either channel (e.g., "channel A" or "channel B"). It should be appreciated that while the embodiments illustrated in <FIG> and <FIG> use leads <NUM>10a, 110b to connect the probe systems 102a, 102b to the monitor <NUM>, a wireless system may also be used wherein the probe is configured to communicate with the monitor without the use of leads <NUM>.

Probe systems (e.g., probe systems 102a and 102b, generally referred to herein as probe system <NUM>) include a set of fasteners 104a,b that may form a vascular coupler that couples two veins and/or arteries in an end-to-end anastomosis (See <FIG>). The probe systems <NUM> may each also include a transducer 106a,b (See <FIG>, <FIG>) connected to at least one of the fasteners104a,b. For example, one ring may include a probe holder with a press-fit Doppler Probe or transducer <NUM>. In an example, a set or pair of fasteners (e.g., set of fasteners 104a, generally referred to herein as fasteners <NUM>) may include a pair of high density polyethylene ("HDPE") rings with stainless steel pins (See <FIG>). The pair of rings form a permanent implant within the patient.

The set or pair of fasteners <NUM> or rings may be sized such that they fit on a similarly sized artery or vein. For example, the fasteners <NUM> or rings may have an inside diameter between <NUM> and <NUM>. In an example, the inside diameter of the fasteners <NUM> may be provided in size increments of <NUM>. It should be appreciated that the fasteners <NUM> or rings may be sized and shaped to accommodate veins and arteries typically encountered in microsurgical and vascular reconstructive procedures and are adapted for end-to-end anastomosis of such veins and arteries in the peripheral vascular system.

The vascular coupler formed from the set or pair of fasteners <NUM> may advantageously reduce anastomotic and flap ischemia time and provide intima-to-intima contact without any intraluminal foreign material (e.g., suture material), which also advantageously decreases the rate of thrombosis. Furthermore, the vascular coupler advantageously stents the anastomosed blood vessel and may be used to correct vessel size discrepancies. For example, the pair of fasteners <NUM> may be used to connect veins or arteries of different sizes. The fasteners also advantageously provide an increased patency rate compared to hand suturing as they provide intima-to-intima contact without any intraluminal foreign material.

The vascular coupler formed by the pair of fasteners <NUM> is adapted to create an end-to-end anastomosis of a blood vessel (e.g., a vein or artery) while retaining and maintaining the position of the transducer(s) <NUM> or other sensing device(s). The sensing devices, in turn, can be used to monitor or evaluate parameters associated with recovery and success of the surgical procedure, such as blood flow at an anastomotic site to confirm vessel patency. As discussed in more detail below, the sensing device(s) or transducer(s) <NUM> enable a medical practitioner (e.g., surgeon) to monitor and analyze the blood flow and/or blood velocity to determine the success of the surgery and/or to confirm vessel patency. The blood flow within the vessel may be monitored and one or more audio samples of the blood flow may be recorded and stored in a database. Storing multiple recordings of blood flow audio samples at different times in the database may allow a medical practitioner (e.g., surgeon) to make comparisons between the recordings. The systems and methods disclosed herein advantageously permit the recordation and evaluation of blood flow data over time to analyze surgery success and patient characteristics (e.g., blood flow and blood velocity). Since anastomotic failures tend to be rather abrupt, the ability to continually and reliably monitor and compare blood flow can be used to generate and send signals associated with the detection of failure events thereby enabling a medical practitioner (e.g., a surgeon) to take corrective action before necrosis sets in and the free flap becomes unusable. Additionally, as described in more detail below, the remote monitoring capabilities of the disclosed system, device and methods advantageously provide remote access so medical practitioners (e.g. surgeons) can detect failure events regardless of their location (e.g., at remote locations) and without degradation of audio quality.

Any transducer 106a,b suitable for ultrasonic Doppler monitoring may be used. In an example embodiment, the Doppler Probe or transducer is made of an approved implantable material such as HDPE or silicone. In another example, the transducer 106a,b comprises a piezoelectric crystal. The transducer 106a,b (hereinafter referred to generally as transducer <NUM>) may be any size conforming to the dimensions of a corresponding transducer receptacle (See <FIG>) used on the fastener of a vascular coupler. For example, a circular transducer <NUM> is suitable to be received by a receptacle having its internal surface circular in shape. The transducer <NUM> may be a circular piezoelectric crystal being between about <NUM> to about <NUM> in size. In one example, the Doppler Probe or transducer <NUM> includes a tip with a circular piezoelectric crystal being between about <NUM> to about <NUM> in size, a Teflon-coated coax wire and a metal connector.

The Doppler Probe or transducer <NUM> may be a <NUM> ultrasonic Doppler transducer that emits a pulsed ultrasonic signal when connected to monitor <NUM> via lead <NUM>. For example, the monitor <NUM> may receive and transmit pulsed waves. In an example (as illustrated in <FIG>) eighteen (<NUM>) pulses of <NUM> are enveloped and sent as transmit pulses to the transducer <NUM>. After receiving the transmit pulses, the pulses may excite the piezoelectric crystal such that the crystal vibrates and sends the ultrasonic signal through the vessel. The enveloped transmit pulses may repeat with a frequency of <NUM>. After the transmit pulses are electronically stopped, the monitor <NUM> may receive or listen for a return signal. For example, monitor <NUM> may switch from transmitting pulses to receive or listen (e.g., for <NUM>) for a Doppler shifted echo immediately (deadband of 150ns) after the transmission pulses. The Doppler shifted echo is transmitted back to the monitor. A varying audible signal (e.g., from the Doppler shifted echo) is produced when the probe or transducer <NUM> detects flow. The audible signal may be processed and filtered by monitor <NUM> before it is made available to the user.

As illustrated in <FIG>, transducer <NUM> may include a percutaneous lead (e.g., lead 108a of probe system 102a and lead 108b of probe system 102b, hereinafter referred to generally as lead <NUM>) attached to its surface. The percutaneous lead <NUM> has a proximal end (e.g., end near transducer <NUM>) and a distal end. The percutaneous lead <NUM> preferably comprises two wires insulated by a common insulating material. The wires may be any wires suitable for monitoring <NUM> signals from the transducer <NUM>. In an example, the insulating materials preferably comprise biocompatible materials, for example class VI medical grade materials. In an example, monitor <NUM> may have a transmission frequency of <NUM> with a continuous reception pulsed wave transmission. The pulses may be repeated at a <NUM> pulse repetition frequency.

At the proximal end, the percutaneous lead <NUM> may have one wire attached to each surface of the transducer <NUM>. Any manufacturing method of attaching the two wires of lead <NUM> to each surface of the transducer <NUM> may be used in order to produce a strong conductive bond with the transducer <NUM> itself. Suitable methods include but are not limited to soldering, friction bonding, adhesive bonding, or attaching the lead during the manufacturing of the transducer. In an example, the bond strength between the transducer <NUM> and the two wires is preferably strong enough to allow for separation of the probe from the receptacles of the fastener by simply pulling on the lead itself. After its use, the transducer may either be left inside of the body within a receptacle, or it may be removed, e.g., by applying enough force to the percutaneous lead <NUM> so as to pull the transducer <NUM> from the receptacle, and to then pull the lead <NUM> through the skin and to the surface of the body. In an example, the strength of the bond between the transducer <NUM> and the percutaneous lead <NUM> is greater than a force necessary to remove the transducer <NUM> from the patient by applying a mechanical force to the percutaneous lead <NUM>.

The distal end of the percutaneous lead <NUM> may be positioned within an optional bonding pad (not pictured) that is placed on the human skin. In an example, the bonding pad may be composed of medical grade material suitable for contact with human skin, for example, USP grade V or VI material. A variety of alternative approaches can be used to attach the lead to the skin, including for instance the use of patches and sutures. The bonding pad or alternative approaches may be attached to the skin in such a way that the force necessary to remove the pad or alternative approaches from the skin must be greater than the force necessary to separate the percutaneous lead <NUM> from an external lead 110a,b (hereinafter referred to generally as external lead <NUM>). In a preferred embodiment, the force necessary to disconnect the percutaneous lead <NUM> from the external lead <NUM> should be less than the force necessary to remove the bonding pad or alternative attachment method (e.g., patch, suture, etc.) from the skin.

As illustrated in <FIG>, the distal end of the percutaneous lead <NUM> may be fitted with a connector 120a,b (hereinafter referred to generally as connector <NUM>) that allows lead <NUM> to be further connected to a proximal end of an external lead <NUM>. The external lead <NUM> is composed of any wire suitable for use in carrying signals and is insulated with materials suitable for skin contact. Preferably, the lead is adapted to carry a <NUM> signal.

Preferably, the connector <NUM> is a medical grade electrical connector. In an example embodiment, the connector <NUM> is a non-locking connector. In another example, connector <NUM> is an electrical medical grade connector. Non-locking connectors are beneficial in reducing the probability of accidental removal of the transducer from the anastomosis site. That is, if the external lead <NUM> is accidentally tugged on, the non-locking connector <NUM> will cause it to disconnect from the percutaneous lead <NUM> without disturbing the transducer <NUM>. The bonding pad or alternative attachment device may also help to prevent the transducer <NUM> from being disturbed.

The distal end of external lead <NUM> is connected to a monitor <NUM>. It may be connected in any suitable manner. In an example embodiment, the lead <NUM> is connected using a connector <NUM> (e.g., connector 130a for external lead 110a and connector 130b for external lead 110b), which may be of the same type as connector <NUM>. Connectors <NUM> and <NUM> may be metallic and may include a plastic housing.

As illustrated in <FIG>, both inputs or channels are utilized and connected to their own Doppler probes. Further, while the preferred multi-component probe system uses leads <NUM>, <NUM> to connect the probe to the monitor <NUM>, a wireless system may also be used wherein the probe is configured to communicate with the monitor <NUM> without the use of leads <NUM>, <NUM>.

<FIG> illustrates a perspective view of a flow monitor system 100B including a multi-component probe system 102a attached to a monitor <NUM> via external lead 110a. The embodiment illustrated in <FIG> shows probe system 102a attached to a single channel (e.g., "channel A") of monitor <NUM>. It should be appreciated that more than two channels may be used. For example, monitor <NUM> may be capable of monitoring more than two channels.

<FIG> illustrates an isometric view of an example embodiment of monitor <NUM> and <FIG> illustrates various other views of monitor <NUM>. Monitor <NUM> includes a housing <NUM> and a display or user interface <NUM>, such as a color LCD touchscreen. Additionally, as illustrated in <FIG>, monitor <NUM> includes speakers <NUM> and a handle <NUM>. The housing <NUM> and handle <NUM> may be made from injection molded plastic (e.g., PC-ABS). Monitor <NUM> may also include various controls associated with the display <NUM> and/or speakers <NUM> such as a volume control <NUM> (e.g., volume control button or membrane switch), a mute control <NUM> (e.g., mute button or membrane switch) and a channel selection controls 224a and 224b (e.g., channel selection buttons or membrane switches for "channel A" and "channel B"). The channel selection controls are associated with connector ports 226a and 226b for receiving external leads <NUM>. In one embodiment, monitor <NUM> may be approximately <NUM>" D x <NUM>" W x <NUM>" H and may weight approximately <NUM> lb (<NUM>). Additionally, as illustrated in <FIG>, monitor <NUM> may include an AC power jack <NUM>, feet 240a-d, and power control <NUM> (e.g., power button or membrane switch). Additionally, monitor <NUM> may have wireless capabilities for remote access to previously recorded audio and/or blood flow data, described in more detail in relation to <FIG>.

<FIG> illustrates a schematic view of various internal components and modules of flow monitor <NUM>. Monitor <NUM> may include a power supply <NUM>, a user interface or display <NUM>, a touchscreen <NUM>, a touchscreen controller <NUM>, a processor <NUM>, memory <NUM>, communication modules (e.g., cell communication module 316a and WiFi communication module 316b), a debug module <NUM>, flash memory such as an ultra secure digital high capacity ("uSDHC") flash memory card, a bootloader <NUM>, test points <NUM> for each channel (e.g., "channel A" and "channel B"), an analog front end ("AFE") <NUM>, a filter module <NUM>, an amplifier ("AMP") <NUM>, speakers 314a and 314b (hereinafter referred to generally as speakers <NUM>), battery <NUM> and battery charge gauge <NUM>.

Processor <NUM> may communicate with touchscreen <NUM> via a serial peripheral interface ("SPI"). The touchscreen <NUM> may be a resistive touchscreen associated with display <NUM>, such as a liquid crystal display. Several of the buttons (e.g., volume control <NUM>, a mute control <NUM>, and a channel selection controls 224a and 224b) illustrated in <FIG> may instead be displayed as graphical representations on display <NUM>, <NUM> which are selectable by touch using touchscreen <NUM>. Memory <NUM> may be DDR2 SDRAM and may temporarily store audio files before they are sent to a remote server or database by one or more of the communication modules. Communication modules (e.g., cell module 316a and WiFi module 316b) may communicate with processor <NUM> via a UART, a USB, a SPI or other acceptable interface to send and receive data from a remote server or database. Similarly, debug module <NUM> and bootloader <NUM> may also communicate with processor <NUM> via an interface (e.g., SPI). In an example, debug module <NUM> and bootloader <NUM> may be utilized for manufacturing tests, diagnostics and repair. The communication modules allow monitor <NUM> to provide remote monitoring to medical practitioners (e.g., surgeons), which will be described in more detail below. However, when on-site, medical practitioners (e.g., nurses and surgeons) may listen to generated audio that is amplified by AMP <NUM> and then sent to speakers 314a, 314b.

The monitor <NUM> generates a signal, which is sent to the transducer <NUM> (e.g., transducer <NUM> or probe emits a pulsed ultrasonic signal) and is transmitted through the vessel site. The transducer <NUM> then detects the signal transmitted through the vessel and sends the detected signal back to the monitor <NUM>, which converts the signals into a form that can be read by the user. An audible signal of varying volume strength is produced when the probe detects flow. For example, the signals may be converted to sound or to a visual display or both.

The frequency (i.e., pitch) of the signal is proportional to the blood flow within the vessel. Distinctive tonal patterns are produced which are indicative of the flow pattern in terms of blood flow vs. time. Tonal patterns provide the surgeon with a qualitative indication of blood flow. The volume of the tone may be adjusted by means of a control on the monitor. A transmitter in the monitor periodically drives the ultrasonic crystal located at the tip of the probe. The ultrasonic waves generated by the crystal travel through the tissue just under the probe tip in a fairly narrow beam. They are then reflected back towards the probe whenever they encounter a boundary between tissues of different densities. During the intervals when the unit is not transmitting, the probe passes any reflected signals that it receives to a receiving circuit. This circuit amplifies the returning echoes, compares their frequency to that of the transmitted signal and converts any frequency differences into an audible tone.

The Doppler Probes and monitor <NUM> may be adapted to detect blood flow at the anastomotic site and confirm vessel patency intra-operatively and post-operatively at the anastomotic site. For example, blood flow can be detected post-operatively for up to approximately <NUM> days. Any monitor/probe combination capable of detecting audio output frequency and blood flow velocity may be used. Preferably, the combination is capable of detecting audio output frequency in the range of about <NUM> to about <NUM> and blood flow velocity in the range of <NUM>/sec to about <NUM>/sec.

In a preferred embodiment, the monitor <NUM> displays a visual numeric value representing the frequency shift of the Doppler signal. The use of a numeric value allows the surgeons to store and trend numbers over time in order to detect and analyze patterns. Optionally, these numbers may also be downloaded into computer software for further analysis. In another preferred embodiment, the monitor <NUM> allows for monitoring of at least two anastomosis sites. In this embodiment, the monitor <NUM> has one or more Doppler probe inputs (e.g., "channel A" and "channel B") and is capable of user selectable monitoring of either channel.

Monitor <NUM> is a pulsed Doppler ultrasound system designed for the detection of blood flow in vessels. The monitor <NUM>, when used in conjunction with a probe system <NUM> may detect blood flow and confirm vessel patency intra-operatively and post-operatively at an anastomotic site. In an example, blood flow may be detected post-operatively on an as needed basis for several days (e.g., <NUM> days) after surgery. In an example, the monitor <NUM> connects to a probe or transducer, such as a <NUM> ultrasonic Doppler Probe or transducer <NUM>, which emits a pulsed ultrasonic signal when connected to monitor <NUM> via lead <NUM>. A varying audible signal is produced when the probe or transducer <NUM> detects flow. The audible signal may be displayed or emitted from monitor <NUM>, as discussed in more detail below.

As illustrated in <FIG>, the display or user interface <NUM> provides a qualitative visual indication <NUM> of blood flow. The visual indication <NUM> may include various bars that each represent a frequency range or blood flow velocity threshold. For example, visual indication <NUM> of monitor <NUM> may be able to indicate blood flow velocities as low as <NUM>/s or <NUM>/s and may also be able to indicate blood flow velocities as high as <NUM>/s. Monitor <NUM> may also emit an audible indication of blood flow via speakers <NUM>. Prior to displaying the visual indication and/or emitting the audible indication, the monitor <NUM> may filter the signal for noise reduction. For example, monitor <NUM> may digitally filter the returned audio signal from the probe or transducer <NUM> to reduce or remove noise.

In another example, monitor <NUM> may display a visual numeric value representing the blood flow or blood flow velocity (e.g., the frequency shift of the Doppler signal). The use of a qualitative visual indication <NUM> or a numeric value allows the medical practitioners (e.g., surgeons) to review an additional indication of blood flow (other than an audio signal) to analyze vessel patency after surgery. Optionally, these numbers and/or visual indications may also be stored in a database (described in more detail below with reference to <FIG> and <FIG>) for further analysis.

Visual indication <NUM>, which is displayed on user interface <NUM> (or on user device <NUM> described in more detail below) advantageously provides a secondary indicator of blood flow to enable a medical practitioner to monitor and analyze a patient's blood flow in noisy environments. For example, an operating room may have several other sources of ambient noise from other medical equipment, other medical personnel, etc. and the visual indication <NUM> may be monitored regardless of the amount of ambient noise. Conversely, the audible indication may be difficult to analyze and distinguish from other sources of interference or noise.

Referring back to <FIG>, the analog front end <NUM> receives signals or pulses from processor <NUM>. For example, AFE <NUM> may receive <NUM> uSec and <NUM> uSec pulses @ <NUM> from processor <NUM>, which are then sent to Doppler probes or transducers <NUM>. Then, AFE <NUM> receives return signals (e.g., of a phase shift) from the transducers <NUM>, which are converted to audio signals and sent to filter <NUM> and/or AMP <NUM>. The audio signals represent a phase shift or a Doppler shift detected by monitor <NUM>, which is converted into audio. For example, ultrasonic energy bounces off red blood cells within a vessel at the anastomotic site, which causes a phase shift if the signal emitted from transducers <NUM>. This phase shift is detected and converted into audio. Specifically, the signal that is proportional to the Doppler shift frequency and also to the blood velocity.

In some cases, especially for low blood flow velocities, the audio sample may be indistinguishable or difficult to distinguish between background noise. Additionally, low blood flow velocities may require a medical practitioner (e.g., a surgeon) to increase the volume of monitor's speakers, which would become distracting or annoying when emitting mostly background noise. Specifically, medical practitioners (e.g., surgeons) determine vessel patency by a distinct sound or audio signal, which is often difficult to detect when lost of muffled with the "hiss" of background noise from speakers <NUM>, <NUM>. By digitally filtering the signal, the audio sample is clearly separated and removed from the background noise so that it can be easily identified and reviewed by a medical practitioner without the annoying "buzz" or "hiss" of background noise emitted from the speakers.

The audio signal may be digitally filtered to control background noise levels. For example, filter module <NUM> may wave shape the audio signal via filter module <NUM>, which may utilize low band pass and high band pass digital filtering. In another example, filter module <NUM> may perform a fast Fourier transform (FFT) of the signal to divide the audio signal into multiple frequency components that are digitally filtered. The digital filtering may include applying a bandpass (low and high) filter and a signal boost (e.g., a boost of <NUM>).

Additionally, audio from low blood flow velocities is typically difficult to distinguish from the low frequency roll-off of the speakers. To improve audio quality, the signal may receive a boost (e.g., a boost of <NUM>) before wave shaping to pull up low-end frequencies up over the low frequency roll-off of the speakers. The digital filtering described herein advantageously improves the noise reduction while the monitor's capability to produce the audible signal remains unchanged while blood flow is detected at specific velocity ranges. Digital filtering advantageously allows a medical practitioner to easily detect low, faint signals associated with a low blood velocity. Without the digital filtering, the audio signal may be lost or muffled within background noise emitted from speakers <NUM>, <NUM>.

<FIG> illustrates an example system <NUM> with monitor <NUM> communicating with one or more of an administration station <NUM>, cloud computing infrastructure <NUM> and a user device <NUM>. The administration station <NUM> may be used to apply configurations and permissions to various mobile devices or user devices <NUM> communicating with the cloud computing infrastructure <NUM>. Monitor <NUM> may include each of the components illustrated in <FIG>. As illustrated in <FIG>, several monitor components (some of which were previously described in <FIG>) are illustrated such as a processor <NUM>, a receiver-transmitter such as a universal asynchronous receiver-transmitter ("UART") <NUM>, a complex programmable logic device ("CPLD") <NUM>, a bootloader <NUM>, a connectivity module <NUM>, memory devices 450a and 450b (referred to generally as memory device <NUM>), and input/output (I/O) device <NUM>.

Monitor <NUM> may communicate with a cloud computing infrastructure <NUM> (e.g., Amazon Web Services ("AWS")), which may include a backend server <NUM> (e.g. backend AWS Elastic Compute Cloud ("EC2") server), an audio server <NUM>, a database search tool (e.g., Mongo DB), and a database <NUM> (e.g., Amazon Simple Storage Service ("S3")). Communication between monitor <NUM> and cloud computing infrastructure <NUM> via communication module <NUM>, such as a WiFi module, may be encrypted. For example, communication encryption at <NUM> may include over-the-air ("OTA") encryption with Wi-Fi Protected Access ("WPA") or Wi-Fi Protected Access II ("WPA2"). Additionally, communication between monitor <NUM> and cloud computing infrastructure <NUM> may utilize a communication protocol at <NUM>, such as Transport Layer Security ("TLS") protocol to provide secure communication on the Internet for data transfers, for example, when transferring a patient's audio files <NUM> to a remote server (e.g., backend server <NUM> or audio server <NUM>) or database <NUM>.

When communicating, backend server <NUM> may request device status or query for latest audio sample from monitor <NUM> at arrow <NUM>. For example, backend server <NUM> may request device status such as transducer ID, what channel on the monitor is active or whether the monitor is actively listening (e.g., recording audio samples). Additionally, backend server <NUM> may query monitor <NUM> for the latest audio sample. For example, device status and/or audio samples of monitor <NUM> may be communicated between connectivity module <NUM> and backend server <NUM>. Additionally, the backend server <NUM> may get audio information, such as an audio file <NUM>, from monitor <NUM> at arrow <NUM> via connectivity module <NUM>. Both the device status information and the audio information may be passed to the database search tool <NUM> at arrow <NUM>. The monitor <NUM> may also upload the audio information, such as audio file <NUM>, to audio server <NUM> at arrow <NUM>. The audio server <NUM> may store data, such as audio information, to the database search tool <NUM> at arrow <NUM>. Additionally, the audio server <NUM> may store audio information, such as audio file <NUM>, to database <NUM> at arrow <NUM>.

Medical practitioners, such as nurses may communicate with and manage data within cloud computing infrastructure <NUM> at arrow <NUM>. In an example, probe or transducer ID or model number, audio identification information, patient identification information, hospital information, or medical practitioner (e.g., surgeon) information may be associated with a specific patient, audio identifier, probe or transducer <NUM>, and or medical practitioner (e.g., surgeon) such that only certain audio files that the surgeon has been given access to can be retrieved by that surgeon through his or her user device <NUM>. The communication between administration station <NUM> and cloud computing infrastructure <NUM> may also utilize a communication protocol such as TLS. Other medical practitioners or privileged users, such as surgeons, may request audio at arrow <NUM> and play audio at arrow <NUM> by communicating with the cloud computing infrastructure <NUM>. Specifically, the user device <NUM> may communicate with the backend server <NUM> and the database <NUM> to play audio file <NUM>.

As used herein, physical processor or processor <NUM> refers to a device capable of executing instructions encoding arithmetic, logical, and/or I/O operations. In one illustrative example, a processor may follow Von Neumann architectural model and may include an arithmetic logic unit (ALU), a control unit, and a plurality of registers. In a further aspect, a processor may be a single core processor which is typically capable of executing one instruction at a time (or process a single pipeline of instructions), or a multicore processor which may simultaneously execute multiple instructions. In another aspect, a processor may be implemented as a single integrated circuit, two or more integrated circuits, or may be a component of a multi-chip module (e.g., in which individual microprocessor dies are included in a single integrated circuit package and hence share a single socket). A processor may also be referred to as a central processing unit (CPU). Additionally a processor may be a microprocessor, microcontroller or microcontroller unit (MCU).

As discussed herein, a memory device <NUM> refers to a volatile or nonvolatile memory device, such as random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or any other device capable of storing data. As discussed herein, I/O device <NUM> refers to a device capable of providing an interface between one or more processor pins and an external device capable of inputting and/or outputting binary data.

Processor <NUM> may be interconnected using a variety of techniques, ranging from a point-to-point processor interconnect, to a system area network, such as an Ethernet-based network. Local connections within monitor <NUM>, including the connections between a processor <NUM>, CPLD <NUM>, connectivity module <NUM>, memory devices <NUM>, and I/O device <NUM> may be provided by one or more local buses of suitable architecture, for example, peripheral component interconnect (PCI).

In some circumstances, a medical practitioner (e.g., a surgeon) may not be on-site to review and analyze the audible indication emitted from monitor <NUM> and/or the qualitative visual indication <NUM> displayed by monitor <NUM>. In those instances, either the patient would have to wait for the surgeon to return to the hospital operating room or post-anesthesia care unit or the information could be conveyed to the surgeon from another practitioner or staff member. For example, in some instances, the surgeon may try to listen to the audible indication (e.g., audio played by monitor <NUM>) in real time over the phone, which may result in a degraded signal depending on cell reception, cell carrier, etc. The inconvenience of having to be on site to review and analyze a patient's blood flow data typically resulted in less frequent monitoring.

To improve the accessibility and ease of monitoring a patient, the user device <NUM> may run an application to remotely access the audio files <NUM> stored on database <NUM>. Medical practitioners (e.g., nurses) may assign access credentials to specific medical practitioners (e.g., surgeons) at the administration station <NUM>. Once provided with access rights or privileges, users (e.g., surgeons) using the monitoring application on user device <NUM> may retrieve and play audio files associated with a specific implanted Doppler probe or transducer <NUM>. For example, blood flow audio files for multiple patients in multiple different hospitals may be stored on database <NUM>, but "Surgeon_A" may be assigned access rights or privileges to listen to audio files associated with "Doppler Probe_A" implanted in "Patient_A". Similarly, "Surgeon_B" may be assigned access rights or privileges to listen to audio files associated with "Doppler Probe B" implanted in "Patient_B" as well as "Doppler Probe_C" implanted in "Patient_C".

When accessing audio files on user device <NUM>, a medical practitioner (e.g., surgeon) may request to listen to a "current" blood flow audio file. For example, as illustrated in <FIG>, a medical practitioner (e.g., surgeon) may select the graphical representation of the "Request-Current" button <NUM> to listen to a "current recording" of the blood flow at the anastomotic site. In an example, selecting the "Request-Current" button <NUM> may initiate a recording and thus may not be a real-time audio signal of the blood flow, but instead may be delayed by a brief period (e.g., <NUM> seconds, <NUM> seconds, <NUM> seconds, etc.). For example, by selecting button <NUM>, a <NUM> second recording of the audio signal of the patient's blood flow may be recorded and uploaded to database <NUM>, which may then be retrieved and played by user device <NUM> to provide an audible indication of blood flow via speakers of user device <NUM>. The application may also allow a medical practitioner (e.g., surgeon) to play, listen to and review previous audio recordings for that patient. For example, by selecting any of the graphical representations of the "Previous Recording_1", "Previous Recording _2", or "Previous Recording_3" buttons <NUM>, <NUM> or <NUM> respectively, the medical practitioner (e.g., surgeon) may listen to previous recordings of the audio signal of the patient's blood flow. By doing so, the surgeon may be able to compare the audio signals and determine if the patient's blood flow is improving, worsening or staying approximately the same.

Recordings may be for time intervals ranging from <NUM> seconds to <NUM> seconds, but it should be appreciated that other time intervals may be used. In another example, the time interval may be selectable by the medical practitioner (e.g., surgeon) through the mobile application.

In another example, the application may provide a qualitative visual indication <NUM> of blood flow, similar to that of the qualitative visual indication <NUM> illustrated in <FIG>. The visual indication <NUM> may include various bars that each represent a frequency range or blood flow velocity threshold. Similar to the qualitative visual indication <NUM> of monitor <NUM> discussed above, qualitative visual indication <NUM> of the application on user device <NUM> may be able to indicate blood flow velocities as low as <NUM>/s or <NUM>/s and as high as <NUM>/s.

For instance, various aspects concerning blood flow within a vessel can be monitored and recorded. With access to several previous recordings, a medical practitioner (e.g., surgeon) can make an objective comparison between a current recording and previous recordings. For example, the qualitative visual indication <NUM> associated with a recording may provide a baseline value that can be compared to other recordings.

The application may display an audio ID <NUM>, a probe ID <NUM> and other recording information <NUM> so that the medical practitioner can confirm which patient and/or probe the audio file corresponds to. Additionally, the recording information <NUM> may indicate the date and time of the recording, etc..

It should be appreciated that user device <NUM> may be a smartphone, tablet, laptop, computer, smartwatch, or any other suitable device.

Claim 1:
A Doppler blood flow monitoring device, comprising:
a signal generation module configured to send a signal to a probe positioned in a probe receptacle on a vascular coupler positioned about a patient's vessel;
a signal reception module configured to receive a return signal from the probe;
a signal filtration module configured to filter the return signal;
a signal conversion module configured to convert the filtered signal into an audible indication and a visual indication (<NUM>, <NUM>) corresponding to a characteristic of blood flow in the patient's vessel;
at least one speaker (<NUM>, <NUM>, 314a-b) configured to emit the audible indication; and
a user interface (<NUM>, <NUM>) configured to display the visual indication (<NUM>, <NUM>),
characterized in that the visual indication (<NUM>, <NUM>) includes various bars that each represent a frequency range or blood flow velocity threshold.