Acoustic access disconnection systems

[0001] This description generally relates to patient access disconnection systems. More specifically, the present description relates to detection of patient access disconnection, e.g., detection of needle or catheter extension during dialysis.

[0002] Fig. 1 shows a known access disconnection configuration. Blood is drained from the patient's arm 12 through the arterial conduit 14 attached to the patient's body via an arterial needle 20. Blood is returned to the patient's body, after treatment, via venous line 18 and venous needle 20. Needles 16 and 20 properly connect with shunt 22 that has fluid connection to one of the arteries and one of the patient's veins. Accidental disconnection of the ductus arteriosus 14 during treatment is not a very serious problem because it simply eliminates the source of blood for the pump. Disruption of venous line connection 18 during treatment is a serious problem because arterial line 14 is still delivering blood to the pump, while venous line 18 returns blood to a place outside the patient's body.

[0003] A variety of different treatments are associated with the passage of fluid into the body, through the body and / or the body of the patient, such as the administration of blood between the patient's body and an extracorporeal system connected to the patient's body via a needle or needles inserted into the body. Treatments such as, for example, plasmapheresis, hemodialysis, hemofiltration and hemodiafiltration are used to remove waste substances, toxins and excess water directly from the patient's blood. During these procedures, the patient is connected to the device and extracorporeal circulation, and the patient's blood is pumped through the device and circuit. Waste substances, toxins and excess water are removed from the patient's blood, and the blood is introduced back into the patient's body.

[0004] In these procedures, needles or similar devices are introduced into the patient's vascular system so that the patient's blood can be transported to and from the extracorporeal circulation device. Traditional hemodialysis, hemofiltration and hemodiafiltration procedures can take several hours and are usually performed at the treatment center about three to four times a week. At the treatment center, patients undergoing hemodialysis, for example, are monitored visually to detect needle protrusion. However, the needle may not be visible to the patient or medical staff (for example, it may be covered by a blanket), which may, for example, delay the detection and response.

[0005] In addition, in view of the improvement in the quality of life, the observed reduction in both morbidity and mortality, and lower costs compared to procedures performed at the centers, the interest in self-care and procedures performed at home has again increased, for example home hemodialysis. Such home treatments (whether hemodialysis, hemofiltration or hemodiafiltration) can be performed during the day, in the evening or at night. If they are performed unattended or while sleeping, the risk of ejection increases because the caregiver is not present and perhaps even the patient is unaware of the ejection.

[0006] There are various systems for detecting needle protrusion during hemodialysis. For example, US Patent Nos. 7,022,098 ("patent '098") and 7,052,480 ("patent' 480"), under the joint title "Access Disconnection Systems And Methods", belonging to the final assignee of this

Reports disclose access disconnection systems that measure the electrical impedance of an extracorporeal dialysis circuit connected to needles providing access to blood vessels.

An external voltage or current source is used to introduce a small current (e.g., less than 2.5 μΑ) into the blood stream. Although this external current is small compared to other systems, it is still required to provide means to ensure that the current does not exceed 10 μΑ, which is considered in the art to be the safety limit for heart access devices. In addition, the impedance system sensitivity may decrease when the patient is connected to ground (for example, using grounding devices in clinics and homes).

[0007] Another problem with systems introducing current into extracorporeal circuits occurs when the needle, after extending, contacts another needle through leaking blood. In this case, the detected electrical parameter, e.g. impedance, may not change or may not change sufficiently to signal disconnection, even if it has occurred.

[0008] Another obstacle occurs when attaching contacts to a single-use blood treatment system part. Metal or other conductive elements contained in the single-use part increase to some extent difficulties and production costs. Document WO 97/10013 discloses a blood vessel access state detection device that uses a pressure wave generator located on one side of a blood vessel access site and a pressure sensor on the other side of an access site.

[0009] US-6,077,443 discloses a device for monitoring access to a blood vessel during a dialysis procedure that includes a pressure pulse generator located in the path of the dialysis fluid, a pressure sensor and an analyzer module.

[0010] US 2003/128 125 discloses a leak detection device that has the ability to detect leaks by at least two different methods to generate at least two leak detection signals.

[0011] WO 00/18451 discloses a system for determining the efficiency of a blood vessel.

[0012] WO 99/29356 discloses a method and device for monitoring the correctness of fluid delivery to an implanted catheter unit. The method includes monitoring signal transmission between the location of the fluid source or a location adjacent to the fluid source and a location further down the fluid path or on the patient's skin.

[0013] Accordingly, there is a need for improved blood access disconnection systems.

Summary of the Invention [0014] According to the present invention, an access disconnection system according to claim 1 is proposed.

[0015] The examples described include a description of access disconnection systems and methods used, for example, for plasmapheresis, hemodialysis ("HD"), hemofiltration ("HF") and hemodiafiltration ("HDF"). Access disconnection systems can also be used in continuous renal replacement therapy ("CRRT") requiring vascular access. The following examples of access disconnection work with systems containing a diffusion membrane or filter, such as a dialyzer for HD or HDF, or a hemofilter for HF.

[0016] Furthermore, each of the systems described can be used in clinical devices or set up at home. For example, the systems can be used in HD, HF, or HDF devices located in centers that work virtually all day. Alternatively, the systems can be used in home HD, HF or HDF devices that are operated when it is convenient for the patient. One such home system is described in the application which is also the subject of the proceedings: US patent application No. 10 / 982,170 ("notification '170") Publication no. US 2005/0131332, under the title "High Convection Home Hemodialysis / Hemofiltration And Sorbent System", PLN November 4, 2004, belonging to the final assignee of this application.

[0017] The following examples of access disconnection work with systems provided with a dialysate (infusion fluid) delivery assembly, which may consist of one or more bags of dialysate coupled together and used one after the other. Alternatively, each of the access disconnection systems described may be used in an apparatus having an on-line source, such as, for example, one or more concentrate pumps adapted to combine one or more concentrates with water to form an on-line dialysate. On-line sources are commonly used, for example, in HD systems.

[0018] Various non-invasive access disconnection systems are described below. The systems basically do not introduce voltage or current into the patient's body. This eliminates the problems associated with patient grounding found in current-inducing systems. Since the operation of these systems is not based on connecting or disconnecting an electrical circuit, they exhibit resistance to the formation of a conductive path with the needle extended and leaking blood. The systems described in various embodiments communicate with the dialysis device wirelessly, e.g., via a radio frequency signal. Thanks to this, these systems are not added to the disposable cable assembly and / or cassette used by the device, which increases ease of implementation and reduces costs.

[0019] The first system uses a piezoelectric or electromagnetic transducer (hereinafter generally referred to as piezoelectric convenience), operating for example in the megahertz frequency range, transmitting ultrasonic waves to the tissue. The transducer body in one embodiment is parallel to the tissue, while the piezoelectric itself is set at an angle to produce a component oriented in the direction of blood flow. [0020] Red blood cells in the blood stream act as reflectors in relation to the ultrasound, giving an echo wave directed back to the transmitter. Another piezoelectric or electromagnetic crystal (hereinafter generally referred to as piezoelectric convenience) can be used to receive echoes. The frequency of ultrasound when the wave is reflected on blood cells changes due to the Doppler effect. Changes in the frequency of the ultrasound signal are an indicator of the speed of reflecting blood cells. The first system processes the received echoes and extracts information about the flow rate.

[0021] The first system, as mentioned, uses a piezoelectric transmitter and piezoelectric receiver, or a single transducer that performs both functions. The transducers, or transducer, are connected to an electronic system that produces excitation signals and processes echoes. In one embodiment, the electronic system also includes a radio frequency ("RF") link with the hemodialysis device. After starting the procedure, the ultrasound device collects information from the blood stream. Some parameters that are monitored in the manner described in detail below are the headlight peak speed, blood flow pulse rate parameters, and site turbulence

-4dostępu. The access disconnection system exchanges this information with the dialysis machine via an RF link. Extending the venous needle inevitably causes a radical change in the measured parameters, enabling detection of access disconnection.

[0022] In one implementation of the first access disconnection system, the ultrasonic transducer is held in place by means of a Velcro tape, magnetic coupling or other fastening. The tape ensures that the cord is held in place, providing mechanical protection against the needle slipping out.

[0023] The second access disconnection system uses sound propagation properties in the blood in extracorporeal circulation to determine, for example, whether the venous segment of the extracorporeal circuit is connected to the patient's body. The second system uses at least one sound transducer that generates an acoustic wave signal that is processed by a dialysis unit that has access to other therapy parameters such as blood flow, dialysis flows, sequential valve control, etc. Acoustic waves can be sound waves, subsonic or pressure waves emitted into the bloodstream. The signals can have any suitable frequency, they can be single-frequency or multi-frequency, they can be continuous, pulse, amplitude, frequency or phase modulated. The acoustic transducer may be a piezoelectric, electromagnetic transducer or any suitable type capable of converting electrical excitation to pressure waves and / or vice versa.

[0024] The second access disconnection system may be implemented in at least three ways. One embodiment, which is not part of the present invention, uses two acoustic transducers, one coupled to the venous section of the extracorporeal circuit and the other coupled to the arterial section of the extracorporeal circuit. One transducer transmits an acoustic signal into the bloodstream, while the other transducer receives the signal. If any of the sections is interrupted, the receiver stops detecting the emitted signal, triggering an alarm. Each of the dual converters can perform both functions, transmit and receive, enabling implementation in which the dual converters exchange functions.

[0025] In a second embodiment, either one acoustic transducer is used, acting in two ways as a transmitter and receiver, or two transducers, one for transmitting and the other for receiving. In this case, both the transmitter and the receiver are coupled to the venous section of the extracorporeal circuit. In this implementation, the transmitter sends an acoustic pulse to the blood. The pulse is reflected in the extracorporeal circuit interface producing a response signature. The system monitors, processes and analyzes the echo signature that arises when a venous line is attached and provides an acoustic reference reference signature. The acoustic signature that occurs when the venous line is disconnected is different from the stored pattern. Processing of the received signal ensures detection of such a change and generating an alarm, switching off or, if necessary, occlusion of the pump and / or valve.

[0026] In a third implementation of the second access disconnection system, a passive sonar is used. The blood stream in the extracorporeal circuit is subjected to a series of operations introducing acoustic waves into it. The blood pump, drip chamber, interaction with the dialyzer and the patient's body give a certain acoustic pattern. This sound pattern is an acoustic signature, and for example will be different when the needle is in the venous line than when it is extended. In the implementation of passive sonar, an acoustic transducer coupled with a wire is used, which acts as a receiver. The receiving transducer monitors, processes and analyzes the acoustic signals in the blood, creating

-5 acoustic reference number. When the pattern changes due to the venous needle protruding, the processing of the received signal ensures the detection of this change and the generation of an alarm, etc.

[0027] The third blood leakage access disconnection / detection system additionally uses optical sensors. It is not unusual that there is a small amount of blood leaking around the areas where the needles connect to the patient's arm. However, this effect should be limited to a small area around access points. If the blood leakage extends over a larger area, it probably means the needle is partially or fully extended, which requires immediate action.

[0028] The optical system in one embodiment uses a flexible circuit with distributed optically reflective sensors. In one implementation, the elastic circumference surrounds the patient's arm. In another embodiment, the optical system comprises a rigid or semi-rigid circuit mounted on a flexible armband made of, for example, plastic, rubber or fabric. The band can also be a disposable article. In any case, the connection assembly may be dimensionally sized and adapted to provide access to blood in another area of ​​the body, e.g., the patient's leg, or catheter access, e.g., in the patient's neck area.

[0029] The elastic circumference may be in contact with a piece of gauze covering the needle insertion point. To ensure sterility, the contact surface is cleaned with a disinfectant. Alternatively, the contact area is covered with a transparent, sterile, disposable film that can be self-adhesive. The foil is thrown away after the procedure.

[0030] The elastic circuit may be attached to the patient's body by means of a velcro-type mechanism, magnetic strips, a magnetic buckle or other type of device providing the possibility of detachable attachment and cleaning.

[0031] Reflecting optical sensors in one embodiment are provided with a light emitting diode as a light source and a photocell or phototransistor as a receiver. The emitted light has a wavelength that is chosen so that the blood dye absorbs its energy. As long as the light falls on white gauze, a certain percentage of its energy is reflected towards the receiver. On the other hand, if blood on gas absorbs almost all light energy, the receiver detects a significant loss of signal and turns on signaling or alarm, etc.

[0032] In one embodiment, the local microcontroller collects data from optical sensors and reports this data via, for example, a radio link to a dialysis device. In one implementation, the microcontroller remains in sleep mode or power saving mode in which the optical sensors are turned off until the dialysis instrument requests data via a radio link. Then the microcontroller "wakes up", turns on the power of light sources, reads the status of optical receivers and transmits it back to the dialysis device. If one (possibly more than one) of the sensors does not receive enough light, the processor reports a state of emergency, and additionally or alternatively, raises an audible alarm. The device takes appropriate action such as shutting down the pump or blocking the pipe or valve.

[0033] In a comparable access disconnection configuration, the dialysis system uses the patient's electrical cardiovascular system to detect access disconnection. Man has an internal electrical system that controls the timing of heartbeats, regulating heart rate and rhythm. Generally, the body's electrical system maintains a steady pulse at rest from

Sixty to one hundred beats per minute. The cardiac electrical system also increases this value to meet the body's needs during physical activity, and lowers it during sleep.

[0034] In particular, the cardiac electrical system controls the pulse timing by sending an electrical signal through cells in the heart, namely conductive cells that carry the electrical signal of the heart, and muscle cells that provide ventricular contractions. The generated electric signal travels through a network of conductive cell paths on the basis of a reaction that allows each cell to stimulate a neighboring cell, and to pass the electrical signal in an orderly manner. Because cells one by one quickly transfer electric charge, the whole heart contracts in one coordinated motion, causing a heartbeat. [0035] The system of the present disclosure uses a kit to generate an electrocardiogram or electrocardiogram ("ECG"). In one embodiment, the first electrode is attached to the venous line and the second electrode is attached to the patient's body. The electrodes are electrically connected to the signal conditioning system. The signal conditioning system generates ECG signals when the arterial and venous connections are made correctly. When there is a partial or complete disconnection of an arterial or venous needle, there is a loss of electrical communication with the body's electrical system through the extracorporeal pathway, and loss of ECG signal. An additional system detects this loss and sends an access disconnection signal to the blood treatment device.

[0036] Alternative ECG solutions include connecting both the first and second electrodes to the extracorporeal circuit. In addition, access to blood can be on or near the patient's heart, which increases the sensitivity to ECG signals, as opposed to access on the patient's shoulder. To this end, the dialysis needle system described herein is equipped with electrodes providing access to the patient's blood on or near the heart. The description further describes various wire systems provided with electrodes provided within the wires, in the wires or outside the wires. Depending on the electrode configuration, the electrodes have a direct electrical connection with the blood, a capacitive, inductive or wireless connection, for example via radio frequency.

[0037] The ECG system is also suitable for adaptation to other applications, apart from detection of vascular access disconnection. ECG signals can be further processed to calculate other physiological parameters such as heart rate variability, respiration, stroke volume, cardiac output and central venous blood volume. For this purpose, an electrical source for bioimpedance measurement may be added to the ECG system. In addition, a solution may be injected into the patient's body to help determine one or more of these parameters. The ECG system can also be used to support patients with cardiac rhythm management devices (pacemakers) by measuring electrophysiology of the heart, for beneficial changes in cardiovascular parameters during dialysis.

[0038] The fourth system uses a blood leak detection device that additionally uses capacitive sensors. The device comprises outer layers of insulation, for example plastic layers. Inside the device contains a set of capacitors. A shielding layer is also used inside the screen. If blood leakage appears under the capacitive device, then the area of ​​capacitors that detect the dielectric change increases. If the area stops growing, the system using a capacitive device assumes that it has requested normal drainage, which is distinguishable from blood leakage or needle dislodging. With sufficient height

In the event of a blood leak, the system uses a capacitive device to determine that access has been partially or completely interrupted and an alarm is triggered.

[0039] In each of the embodiments of the access disconnection described above, the circuitry for the access disconnection systems may be located locally on the patient's body or at the measurement site, remotely inside the device, or in accordance with some combination of these solutions. Depending on the location of the circuitry, the signal sent from the access disconnection system to the dialysis machine may be a continuous signal, e.g., a conditioned digital signal, a discontinuous signal, a signal sent on demand, or some combination thereof. The signal can be sent via wires or wirelessly.

[0040] Furthermore, each of the above-described embodiments of the blood leakage access disconnection / detection system may also be used in a redundant system, together with another type of blood leakage access disconnection / detection system.

[0041] It is therefore an advantage of the present invention to provide an improved access disconnection system for blood treatment devices.

[0042] Another advantage of the present invention is to provide non-invasive access disconnection systems.

[0043] A further advantage of the present invention is to provide an access disconnection system that does not induce current in the patient's blood.

[0044] Still another advantage of the present invention is to provide access disconnection systems that do not introduce additional ad hoc or production costs.

[0045] Still another advantage of the present invention is to provide access disconnection systems that bypass problems with secondary electrical connection due to blood loss.

[0046] Yet another advantage of the present invention is to provide an access disconnection system that provides other valuable information about blood parameters.

[0047] Still another advantage of the present invention is to provide access disconnection systems that are compatible with the needle and blood catheter applications.

[0048] Additional features and advantages of the invention are described below, and are apparent from the following detailed description and drawings.

Description of the figures [0049] Fig. 1 shows the known arterial and venous access configuration.

[0050] Fig. 2 is a vertical cross section showing one embodiment of an ultrasound access disconnection system.

[0051] Fig. 3 is a perspective view of the system of Fig. 2 and one of its implementations for communication with a blood treatment device.

[0052] Fig. 4 is a schematic of one embodiment of the electronic systems associated with the system of Fig. 2.

[0053] Fig. 5 is a schematic layout for simulating the ultrasonic access disconnection system of Fig. 2.

[0054] Fig. 6 is a graph illustrating the results of the test performed on the simulation example of Fig. 5.

[0055] Fig. 7 is a perspective view of an access disconnection system that uses two acoustic transducers.

[0056] Fig. 8 is a perspective view of an additional embodiment of an acoustic access disconnection system that uses active sonar and which is shown with the system in the transmit phase.

[0057] Fig. 9 is a perspective view of either (i) the receiving phase of an active sonar system according to Fig. 8, or (ii) an alternative embodiment using a passive sonar system, both systems "listening" or (i) the echo of the active signal transmitted or (ii) acoustic signature of the extracorporeal circuit in the passive system [0058] Fig. 10 is a perspective view of the optical access disconnection system [0059] 11 is a perspective view showing the flexible circuit used with the optical access disconnection system of Fig. 10.

[0060] Fig. 12 is a schematic vertical section of the optical access disconnection system of Fig. 10 in a normal state.

[0061] Fig. 13 is a schematic vertical section of the access disconnection system of Fig. 10 in an access disconnected state.

[0062] Fig. 14 is a perspective view of the optical system of Fig. 10 and one of its configurations to provide communication with the blood processing device.

[0063] Fig. 15 is a diagram of a system using electrocardiographic ("ECG") signals to detect access disconnection.

[0064] Fig. 16 is a schematic of another system using electrocardiographic ("ECG") signals to detect access disconnection.

[0065] Fig. 17 is a view of the cardiac catheter used in the ECG system of Fig. 16.

[0066] Figs. 18A to 18C show different configurations to provide electrical contact with the patient's blood, these configurations are suitable for use with the systems of Figs. 16 and 17. [0067] Figs. 19A and 19B are a top view and side view of a blood leak detection device with capacitive sensors.

Description of Embodiments [0068] The examples described herein refer to any medical fluid therapy system requiring vascular access. The examples are particularly well suited to control the treatment of renal failure, for example all types of hemodialysis ("HD"), hemofiltration ("HF"), hemodiafiltration ("HDF") and continuous renal replacement therapy ("CRRT") requiring vascular access.

Ultrasonic Remote Access Disconnection Sensor [0069] The figures, and in particular Figs. 2 to 4, show the ultrasonic access disconnection system 10. Fig. 2 shows the details of the system 10. Fig. 3 shows one device for attaching the system 10 to the patient's body 12. Fig. 3 also shows one embodiment for providing a system interface 10 to a blood treatment device or dialysis device 100. Although system 10 generally refers to a remote device connected to the patient's body, as seen in Figure 2, system 10, and even all systems described herein, also includes a device or device such as a dialysis device. Fig. 4 shows an embodiment of the electronic system

-9 (either local or remote electronics) associated with the system 10. Figures 5 and 6 show the test results.

[0070] Each of the examples of vessel detachment described herein, including system 10, is suitable for operation with a device 100 that may include a diffusion membrane or diffusion filter such as a dialyzer e.g. for HD or HDF, or a hemofilter, e.g. for HF. In addition, the device 100 and any of the access disconnection systems described may be used in a clinical or home configuration. For example, the device 100 and access disconnection systems can be used in an HD device in the facility, i.e. virtually throughout the day. Alternatively, they can be used in an HD home device that can, for example, be operated at night while the patient is asleep.

[0071] The device 100 in one embodiment has a source of dialysate (infusion fluid). Alternatively, many dialysate bags are coupled together and are used one after the other. In this case, empty bags can be used as drain bags or fluid bags. In another embodiment, the device 100 may be used with an on-line source, for example, one or more concentrate pumps adapted to combine one or more concentrates with water to form an on-line dialysate. On-line sources are commonly used, for example, with HD systems.

[0072] Although not shown, the device 100 can operate with a permanently turned on or batch heater that heats the dialysate or infusion fluid to the desired temperature. The heater can be placed, for example, upstream or downstream of the feed pump. The device 100 includes a dialysate siphon, which can be positioned at or near the radiator to trap the air escaping from the dialysate due to heating. Similarly, an extracorporeal circuit designed to cooperate with a blood pump 102 also includes one or more air detectors and an air removal device (e.g., a siphon).

[0073] The HD, HF, HDF or CRRT 100 also includes blood pumping systems, as shown below, which are generally known in the art, using, for example, one or more peristaltic blood pumps. The HD, HF, HDF or CRRT 100 device contains the aforementioned dialysate dispensing systems, which are also known and require no description.

[0074] The device 100 also includes a device and method for determining how much dialysate to be used for purification and what volume is removed by ultrafiltration. This device controls and knows how much ultrafiltrate has been removed from the patient and controls the flow rate of dialysate to and from the dialyzer, extracorporeal circuit and / or hemofilter. The device also ensures that the necessary amount of ultrafiltrate is removed by the patient until the end of the procedure.

[0075] The device 100 includes a housing 104, as shown in Fig. 3. The housing 104 varies depending on the type of surgery and whether the procedure is in the center, or is a home procedure, and whether the dialysate / infusion fluid supply is of the type batch (for example with bags) or continuous (on-line). There is a tendency to use in the medium conditions housing 104 working in a continuous manner, larger and more durable, due to the additional equipment producing dialysate and the frequency of using such devices. The home treatment housing 104 is preferably smaller and constructed so that the device 100 can be moved in the patient's home or transported on the go.

[0076] In Figure 2 it can be seen that the system 10 comprises a transducer 24. The transducer 24 in the embodiment shown comprises a housing 26 in which a piezoelectric crystal 28 is located. The transducer 24 transfers power from one type of system to another. In a piezoelectric implementation, the power of the transducer 24 is given in the form of electricity acting on the piezoelectric material. System 10 includes a device for activating the transducer 42 as shown in FIG. 4, which applies an electric field to the piezoelectric crystal 28. Piezoelectric crystal 28 undergoes mechanical deformation under the influence of an electric field. In this way, the crystal 28 is stimulated to resonate (vibrate) at a certain frequency, and to produce ultrasonic waves. In one embodiment, the ultrasonic waves are generated in the megahertz frequency range. In one embodiment, the coupling of waves to the patient's body is provided by a gel layer. Ultrasonic waves encountering human tissue travel through this tissue to a depth that depends on the power and frequency of excitation.

[0077] The transducer housing 26 in the embodiment shown is disposed parallel to the arm and tissue of the patient 12. The crystal 28 on the other hand is positioned at an angle, for example forty-five degrees, relative to the arm and tissue of the patient 12, and generates ultrasonic waves 30a having directional components both parallel and perpendicular to the direction of blood flow.

[0078] Blood cells 32, e.g. red blood cells, act as ultrasound reflectors in the blood stream, reflect waves 30b back towards the second piezoelectric crystal 34. However, it should be noted that the first piezoelectric crystal 28 can perform both transmitter and receiver functions. and in this case the second crystal 34 is not necessary. In the embodiment shown, the receiving crystal 34 is located in the housing 26 of the same transducer 24 as the transmitting crystal 28. Alternatively, the receiving crystal 34 is in a separate transducer housing. In the embodiment shown, the receiving crystal 34 is also mounted at an angle, e.g., forty-five degrees, relative to the arm and tissue of the patient 12.

[0079] In the case of piezoelectric receiving crystal 34, reflected waves 30b cause mechanical stress in the receiving crystal 34, causing the crystal 34 to electrically charge and vibrate at its resonance frequency, resulting in an ultrasonic wave. The reflected ultrasonic waves 30b have a different frequency than the emitted ultrasonic waves 30a, this phenomenon is known as the Doppler effect. The change in frequency depends on the speed and direction of movement of the blood cells 32 flowing at the access site. The electronics in the system 10 store software that processes the received echoes 30b determining blood parameters such as red blood flow rate, peak headlight flow rate, changes in blood flow rate, e.g. blood flow pulse rate parameters, turbulence in the access tube, as described below more specific.

[0080] In the embodiment shown in Figure 3, the transducer 24 and electronics described below are held in place by means of tapes 36. The tapes 36 have suitable fasteners, such as Velcro ™ fasteners or other types of friction, button or snap fasteners. The tapes 36 perform a second function, namely Figure 2 shows that the strap 36 holds the transducer 24 against the body of the patient 12 via a gel 38. Gel 38 provides coupling of the ultrasonic wave to the patient's tissue. [0081] Fig. 4 shows an embodiment of an electronic system associated with the system 10.

A digital signal processor ("DSP" - digital signal processor) 44 that may contain local memory

- 11 Random Access Memory (RAM) and read only memory ("ROM" - read only memory), sends an output signal to the excitation device of the transducer 42. The excitation device 42 stimulates the crystal of the emitter 28 of the transducer 24, as described above . The reflected waves 30b cause the receiving crystal 34 (or crystal 28 acting as both transmitter and receiver) to vibrate and produce an ultrasonic wave, which is sent to signal conditioning assembly 40. In one embodiment, the signal conditioning assembly 40 includes an analog-to-digital ("A / D") converter that digitizes the reflected wave into a form that is capable of being processed by DSP 44. The signal conditioning assembly 40 may, in another embodiment, include a demodulation circuit for separating signal components for example in a manner useful for Doppler calculations.

[0082] In one embodiment, the local DSP software detects a flow or access state, no flow, a state of complete or partial disconnection of access. The DSP 44 also uses conditioned signals to detect the blood flow rate, for example by associating a specific frequency with a specific blood flow rate. Correlation can be determined empirically and checked for repeatability. The peak frequency corresponds to the peak blood flow rate. The DSP 44 also detects changes in blood flow rate even when it does not rise to a level indicating access interruption. This information can be used, for example, to determine blood flow turbulence, which in turn can be used, for example, diagnostically to determine or determine the effectiveness or efficiency of therapy.

[0083] The DSP 44 communicates in both directions via a remote or wireless transmitter / receiver 46, e.g. a radio frequency ("RF") transmitter / receiver. It is also possible to use other remote signals, e.g. microwave signal. Alternatively, system 10 is permanently connected to device 100 and communicates using electrical signals, e.g., 4 to 20 mA or 0 to 5 V DC signals.

[0084] The device 100 includes a wireless transceiver 48, for example an RF transceiver. In system 10, the communicator 48 of the device 100 sends and receives messages to and from the remote unit via the communicator 46. The communicator 48 in turn communicates bilaterally with the central processing unit ("CPU") 50 located within the device 100. In one embodiment, the CPU 50 includes a supervisory processor that communicates via signals 56 with one or more dedicated processors and an electronic circuit board or controller located in the device 100. In the embodiment shown, the transducer 24, the signal conditioning assembly 40, the device excitation 42, DSP 44 and transmitter 46 are located on the printed circuit board ("PCB") 52. The PCB 52 can be housed in the transmitter housing 26, in a separate housing (not shown), or in a housing that also has one or more transmitters 24. In an alternative embodiment, the DSP 44 processor and associated functionality fit in and are performed in CPU 50 of device 100, respectively.

[0085] The PCB 52 also includes a battery, power supply, or a combination of both, which is generally referred to herein as power supply 54. The power supply 54 may, for example, be a battery. The power supply 54 powers the components of the PCB 52, for example the signal conditioning unit, DSP 44 processor and wireless communicator 46. In one of

- 12 embodiments, the power supply 54 is rechargeable and may be coupled with an acoustic, visual or audiovisual alarm to alert the patient when the power supply needs to be recharged or replaced. [0086] In the embodiment shown in Figure 4, the remote wireless communicator or transceiver 46 communicates with the device communicator 48 via radio signal 58. Signal 58 may be one of the following types: electric signal, radio frequency signal, microwave signal, continuous signal, discontinuous signal, signal sent only when the sensor detects change, and any suitable combination thereof. FIG. 3 shows that in one embodiment, signal 58 is a continuous, e.g., digitized, data stream that CPU CPU 50 (via RAM 42 and DSP 44 and related functions located in device 100) uses to determine blood flow rate, peak flow rate, blood flow pulse rate parameters, turbulence, and the like. If an access interruption occurs, the frequency of the reflected ultrasonic waves 30b changes significantly enough, such as the output value of the corresponding signal 58, for the software in the buffering RAM 42 to detect a partial or complete interruption of access. When access interruption is detected, the CPU 50 via signals 56 causes other components in the device 100 to take appropriate action, e.g., causes and / or sounds an acoustic, optical or audiovisual alarm in the graphical user interface 106 of the device 100. The CPU will also likely cause turning off the blood pump 102.

[0087] In an alternative embodiment, the reflection wave processing 30b takes place on the plate

PCB 52. In this case, the local DSP 44 determines the blood flow rate, peak flow rate, blood flow pulse rate parameters, turbulence, and the like. DSP 44 sends this information wirelessly via transmitter 46 to processor 50 at predetermined intervals or when the CPU 50 requests such information. When the access disconnection is detected, the DSP via the transmitter 46 sends an alarm signal 58 to the CPU 50, which causes the appropriate action to be taken on other components of the device 100 as described above. Thus, radio signal 58 may be a continuous signal, an intermittent signal or a signal sent only after a change has been detected, or any suitable combination of these signals.

[0088] In another alternative, the PCB 52 includes an acoustic, optical or audiovisual alarm system that alerts the patient that access is interrupted. In this embodiment, the system 10 may or may not contact the device 100. For example, the PCB 52 may turn on an audible alarm while the device 100 turns off one or more pumps and clamps or closes one or more wires or valves.

[0089] Fig. 5 schematically illustrates a test that was performed using an ultrasonic sensor, for example transducer 24, shown in Fig. 2, placed at the blood vessel of patient 12 behind the venous needle 20, also seen in Fig. 2. It should be noted that the systems described herein can operate with standard access needles 16 and 20 or with catheters of the type used for the subclavian vein. As can be seen in Fig. 5, the patient's arm is modeled through a tube. An ultrasonic sensor is placed on the pipe. The patient's blood is modeled with a saline solution, which the access pump pumps approximately one liter per minute through an equalizing chamber of five hundred cubic centimeters, through a tube (patient modeling) and back to the source of the saline solution. Arterial and venous needles 16 and 20 shown schematically in Fig. 5 are inserted and attached to the representing tube

-13 patient's hand. The modeled extracorporeal circuit includes a blood pump, drip chamber, in combination with a pressure sensor, dialyzer and venous pressure sensor.

[0090] Fig. 6 shows that when sliding out of the venous access tube 20, the ultrasonic sensor found a noticeable decrease in flow rate by about 300 ml per minute. This means that only 700 ml per minute returned from the pump pumped by the access pump in Fig. 5, which was detected by the ultrasonic sensor.

Acoustic Access Disconnection Sensor [0091] Figures 7 to 9 illustrate various embodiments of acoustic access disconnection systems in the form of systems 60a to 60c (referred to herein as acoustic access disconnection systems 60 or generally as acoustic access disconnection system 60). Acoustic access disconnection systems 60 have many similarities to the ultrasonic access disconnection system 10. Both are used in the device 100 (and any of its alternative configurations discussed above), have the option of remote signaling, are non-invasive, do not require passing blood through the patient's blood, or add elements to the cassette or set of disposable cables, provide reduced costs and the possibility of additional blood parameters measurements. Both systems, 10 and 60, use acoustic waves.

[0092] One of the main differences of systems 60 is that transducers and associated electronics are coupled to arterial and venous lines 14 and 18, rather than to the patient's body 12. This configuration can be advantageous because disconnecting one of the wires 14 and 18 should give a relatively radical change in reflected waves. Additional measurements of blood parameters reflect features of blood flow in the extracorporeal circulation, instead of features of blood flow in the patient's body, as in the case of system 10, which may be beneficial or disadvantageous.

[0093] Fig. 7 shows an acoustic access system 60a with a dual transceiver / receiver. The acoustic access system 60a includes a circuit board 66 on which transducers 62 and 64, signal conditioning assembly 40, excitation device 42, DSP processor 44 (including built-in memory), wireless transceiver 46 and transceiver 54 described above are placed. The power supply 54, as mentioned above, powers the excitation device 42, DSP processor 44 and wireless transmitter / receiver 46, which operate as described above with respect to system 10. DSP processor 44 communicates bidirectionally with a remote transmitter / receiver 46 that communicates bidirectional with the transmitter / receiver of 48 devices. In an alternative embodiment, as in the case of the system 10, one or more devices and functions associated with the DSP processor 44 are located in the device 100. The device 100 as previously comprises a wireless, e.g. a radio, transceiver 48 for sending and receiving signals 58 to and from the wireless transceiver 46. Alternatively, the device 100 is wired to the system 60a to provide electrical communication.

[0094] The transmitting acoustic transducer 62 transmits an acoustic signal to the arterial conduit 14 via the excitation device 42, and the receiving acoustic transducer 64 receives the signal from the venous conduit 18. Alternatively, the transducer 62 transmits the acoustic signal to the venous conduit 18 and the receiving acoustic transducer 64 receives a signal from the ductus arteriosus 14. Transducers 62 and 64 can be of the type that each of them can be constructed as a transmitter or receiver. Alternatively, each of the transducers 62 and 64 can be both a transmitter,

-14 as a receiver. In this case, the roles of transducers 62 and 64 can be reversed after an access disconnection event occurs to provide redundant control. The roles of the transducers 62 and 64 can be swapped under normal operating conditions to check that the transducers are working properly and to provide redundancy for other parameters detected by the 60a system. [0095] In one embodiment, transducers 62 and 64 emit and receive waves that are sound, subsonic or pressure waves, and for example the signal can be transmitted on one or many frequencies. The transducer 62 may emit waves in a continuous, discontinuous or pulsed manner. In addition, the produced signal may be modulated according to any or more combinations in amplitude, frequency and phase. In a preferred embodiment, the signal differs from naturally occurring waves, which also can be detected by the receiving transducer 64.

[0096] The excitation device 42 stimulates the emitter transducer 62 to emit sound waves towards the patient's body 12. Similarly, the receiver acoustic transducer 64 is also adapted to receive sound waves from the patient's body. In this way, the likelihood that the sound waves will travel from the transducer 62, through the blood pump 102, to the transducer 64 is minimized. In addition, the drip chamber located in one or both ducts, arterial or venous, provides separation by an air barrier in the extracorporeal circuit, which is to minimize the coupling of the sound wave towards the blood pump. This directional configuration also maximizes the difference in signal reception when access is interrupted.

[0097] The signal conditioning assembly 40 (for example, the A / D converter) conditions the signal for the DSP 44. It should be noted that the signal conditioning assembly can alternatively be located in the DSP 44. The DSP 44 processes the conditioned signals using the built-in or separate buffer memory RAM. The DSP communicates with the transceiver 46, which in turn sends and receives data from the transceiver 48 of the device. The transceiver 46 may alternatively be located inside the DSP 44. In any case, the DSP 44 may be adapted to detect the projection by measuring the loss of audio signal power during disconnection. The DSP 44 can also calculate blood flow rate, peak flow rate, and any other parameters described herein.

[0098] If either the ductus arteriosus 14 or the venous duct 18 is partially or completely extended from the body of the patient 12, communication between transducers 62 and 64 is interrupted or changed significantly, such that access disconnection is established and any of the discussed is implemented here, protective measures, e.g. alarm, pump shutdown, valve closing, hose clamping. In the illustrated embodiment, the processing of the event of a rupture or interruption of communication between transducers 62 and 64 takes place on the PCB 66. Here, under normal operating conditions, the PCB 66 determines the strength and frequency of the received signal, and potentially the blood flow rate, peak flow rate, pulse parameters blood flow, turbulence, etc., as described above. This information is transmitted wirelessly via the transceiver 46 to the processor 50 of the device 100 continuously at specified intervals, or when the CPU 50 requests such information. When an access disconnection is detected, the DSP sends an alarm signal 58 to the CPU 50 via transmitter 46, which causes the components in the device 100 to take appropriate action as described above. Radio signal 58 may be

Respectively, by a continuous signal, an intermittent signal, a signal sent only after a change has been detected, or any suitable combination of these signals.

[0099] In an alternative embodiment, the individual components of the PCB 66 are in the device 100, e.g. DSP 44. In this case, the RF signal 58 is a continuous data stream that can be conditioned, e.g. digitized, locally and sent to the CPU 50 devices 100. DSP 44, now inside device 100, uses data stream 58 to determine the strength and frequency of the received signal, and potentially blood flow rate, peak flow, blood flow pulse rate parameters, turbulence, and the like inside device 100. If access interruption occurs, then the data contained in RF 58 changes so much that the software inside the device 100 detects partial or complete interruption of access. When an access disconnection is detected, the CPU 50 causes, for example, via a dedicated controller, to take appropriate protective action by other components in the device 100, as described above.

[0100] In another alternative, the PCB 66 includes an audible, optical or audiovisual alarm that alerts the patient to interruption of access. In this embodiment, the system 10 may, although not necessarily, contact the device 100.

[0101] In turn, in Figures 8 and 9, the active sonar system, or echo system 60b, uses either a single acoustic transducer 68, used twice as a transmitter and receiver (as shown in the figure), or two transducers, one transmitting and one receiving . In either case, single or double transducers are coupled to one of the extracorporeal ducts, e.g. venous duct 18 in one preferred embodiment (as described above, the protrusion of the venous access duct is potentially more dangerous than the protrusion of the arterial duct).

[0102] The active sonar or echo system 60b includes a printed circuit board 70 on which the signal conditioning assembly 40, excitation assembly 42, DSP processor 44, remote wireless transceiver 46 and power supply 54 described above are provided. Power supply 54 powers the assembly signal conditioning 40, DSP 44 and transceiver 46. In an alternative embodiment, as in the case of the system 10 above, one DSP 44 is located in the device 100. The device 100, as before, includes a wireless, e.g. radio, RF, transceiver 48 for receiving signals from the radio transmitter 46. Alternatively, the device 100 is wired to the system 60b to provide electrical communication.

[0103] In the embodiment shown, the acoustic transmitting transducer 68 transmits the acoustic signal to the venous conduit 18. The signal is reflected in the conductors 14, 18 of the extracorporeal circuit and in the transplant 22, creating a response signature. Signal conditioning assembly 40 processes response signatures, e.g., digitizes it, and sends a digital signal to DSP 44 (which may include RAM, ROM, embedded signal conditioning assembly, and / or embedded transceiver) located either locally on board 70 or in device 100. In one implementation, the DSP 44 processor utilizes internal software to analyze the signal. DSP 44 formulates the acoustic reference signature of the reflected acoustic wave and stores this reference signal in RAM 42.

[0104] The acoustic transmitting / receiving transducer 68 is adapted to emit sound waves towards the patient 12. The transducer 68 is also adapted to receive sound waves from the patient's body. The likelihood that the sound waves will travel from transducer 68 around the blood pump 102 back to transducer 68 is minimal, at least in part due to the drip chamber which is located between the transducer and the blood pump in the arterial blood line. This directional configuration also maximizes the difference in signal reception when access interruption occurs.

[0105] If partial or complete disconnection of patient 12 or arterial duct 14 or venous duct 18 occurs, then the response signature returning to transducer 68 is damaged or changed so significantly compared to the reference signature that access disconnection is determined and implementation any of the described actions, e.g. turning on the alarm, stopping the pump, closing the valve, tightening the hose.

[0106] In the embodiment shown, the processing of the difference between the received response and the reference response takes place on the PCB 70. At the same time, under normal operating conditions, the embedded DSP 44 determines the power, frequency and envelope shape of the received signal, and potentially the peak blood flow rate flow rate, heart rate parameters in blood flow, turbulence and the like. This information is transmitted wirelessly via DSP 44 and communicator 46 to the CPU 50 on a continuous basis at specified intervals or when the CPU 50 requests such information. When an access disconnection is detected, the DSP 44 via the communicator 46 sends an alarm signal to the CPU 50, which causes other components in the device 100 to take appropriate action, as described above. Accordingly, the wireless signal may be a continuous signal, an intermittent signal, a signal transmitted only when a change is detected, and any suitable combination of these signals.

[0107] In an alternative embodiment, most of the components of the PCB 70 reside in the device 100. In this case, the RF signal 58 is a continuous data stream that can be conditioned, for example digitized, locally and sent to the CPU of the device 100 that operates with DSP 44 processor and its associated functions. Data stream 58 is used to determine blood flow rate, peak flow rate, heart rate parameters, turbulence, and the like in device 100. If access is interrupted, RF signal 58 is interrupted or shrinks enough to cause buffering software DSP 44 detects partial or complete interruption of access. When an access disconnection is detected, the CPU 50 causes other components in the device 100 to take appropriate action, as has already been described.

[0108] In another alternative, the PCB 70 includes an acoustic alarm of access interruption. In this embodiment, the system 10 may, although not necessarily, contact the device 100.

[0109] As shown in Fig. 9, the passive sonar or signature 60c system uses a single receiving transducer 64. In one preferred embodiment, the transducer 64 is coupled to one of the extracorporeal wires, e.g., venous line 18 (as described above, interruption of venous access is potentially more dangerous than interruption of arterial access).

[0110] The passive sonar or acoustic signature 60c system includes a printed circuit board 70 on which the signal conditioning assembly 40 described above is located, the excitation device

42, DSP 44 processor, wireless communicator 46 and power supply 54. In an alternative embodiment, as in the above systems, one or more devices and associated functionalities of DSP 44 processor are located in device 100.

[0111] The passive sonar system 60c uses pulses generated by the system blood pump, drip chamber, interaction with a dialyzer or other extracorporeal device. These devices form an acoustic pattern or response signature in the receiving transducer 64 similar to the response signature described above. The signal conditioning assembly 40 processes the response signature, e.g., digitizes it and sends a digital signal to the DSP processor 44 located either locally on the PCB 70 or in the device 100. In one embodiment, the DSP processor 44 analyzes the signal using embedded software. The DSP 44 formulates the acoustic reference signature of the reflected acoustic wave and stores the reference signal in memory.

[0112] If, in the embodiment shown, the venous line 18 extends partially or completely from the body of the patient 12, the response signature returned to the transducer 68 is damaged or changed so much compared to the acoustic reference signature that access disconnection is determined. Then, any of the actions described in this document is performed, for example, an alarm, shutting down the pump, closing the valve, tightening the hose.

[0113] In the embodiment shown, the processing of the difference between the received response and the reference response takes place on the PCB 70 of the system 60c. In this case, under normal operating conditions, the embedded DSP 44 determines the blood flow rate, peak flow rate, blood flow pulse parameters, turbulence, and the like. This information is transmitted wirelessly via DSP 44 and transceiver 46 to the CPU 50 continuously, at predetermined intervals, or when the CPU 50 requests such information. Upon detecting an access disconnection, the DSP 44 via the transceiver 46 sends an alarm signal to the CPU 50, which causes the other components of the device 100 to take appropriate action, as already described.

[0114] In an alternative embodiment, DSP 44 is disposed in the device

100. In this case, the RF 58 signal is a continuous data stream that can be conditioned, e.g. digitized, locally and sent to the CPU of the device 100 via RF radio communication. Data stream 58 can be used to determine blood flow rate, peak flow rate, blood flow pulse rate parameters, turbulence, and the like at device 100. If access disconnection occurs, the RF 58 signal is interrupted or weakened so that programming in the DSP buffering processor 44 detects partial or complete interruption of access. When an access disconnection is detected, the CPU 50 causes, for example, via a dedicated controller, to take appropriate action by the other components in the device 100 as described above.

[0115] In another alternative, system PCB 70 of system 60c includes an acoustic, optical or audiovisual alarm system that notifies the patient of access interruption. In this embodiment, the system 10 may, though not necessarily, communicate with the device 100.

[0116] Figures 10 to 14 show the optical access disconnection / blood leakage detection system 80. The optical access disconnection / blood leakage detection system 80 uses a gauze that is usually laid over the access needles 16 and 20 on the patient's body 12. It is not unusual that under normal operating conditions around the access points where the needles 16 and 20 connect to the patient's arm 12, there is a small leakage. However, normal blood leakage should be limited to a small area around the access needles 16 and 20. If the blood leakage covers a larger area, it is likely that the needle has extended and must be removed immediately.

[0117] Fig. 10 shows that the optical access disconnection / blood leakage detection system 80 is an elastic band 90. An elastic band 90 surrounds the patient's arm 12. In one configuration, the elastic band 90 is placed on a gauze pad 82 of Fig. 10, which, as mentioned above, is arranged on the access needles 16 and 20. Because the elastic band 90 contacts the gauze 82, the need for sterility must be considered. In one configuration, the elastic band 90 is cleaned with a disinfectant before being applied to gauze 82. Alternatively, gauze 82 is covered with sterile disposable foil 84, which may be self-adhesive. The foil 84 is thrown away after the procedure. Foil 84 insulates the elastic band 90 from the contact surface.

[0118] The system with elastic band 90 provides preventive action against needle protrusion. Wrapped around the needle and wires, the elastic band 90 fixes the needles and wires and accordingly prevents them from slipping out. The system with the elastic band 90 limits the connections between the fistulas and their associated conduits to the area covered with the elastic band 90, so that the system can also detect the separation between the stoma and the conduit.

[0119] Fig. 11 shows that the elastic band 90 in one configuration is provided with fasteners 86A to 86C running around the elastic band 90 and joining, for example, thorns and / or by sticking, with their cooperating contacts 88a to 88c. For example, tabs 86 (tag designation 86a to 86c) can be connected to contacts 88 (tag designation 88a to 88C) by Velcro ™ fasteners, buttons, slots, folds, or other types of release attachments. If it turns out that the fasteners 86 and contacts 88 are difficult to clean, they can, as in one embodiment, be replaced by more hygienic joining methods, such as magnetic strips and buckles.

[0120] As shown in Figs. 10 and 11, the elastic band 90 includes a number of reflective photoelectric sensors 92a to 92e, each of which is powered by leads 94a to 94e, respectively, for connecting a power source 54, e.g. a button cell battery. In one configuration, the optical sensors 92 (collective term for sensors 92a to 92e) comprise a light emitting diode ("LED") acting as a light source and a photocell or phototransistor, acting as light receivers. The LED and photocell are adapted to a specific wavelength that allows maximum absorption at reflection from the blood. The prototype of the 80 optical system has successfully used LED / photocell combinations, such as those used in blood leak detectors for hemodialysis.

[0121] In one configuration of lead 94 (collective term of leads 94a to 94d) are paths, for example copper paths, which are applied, in a known process, to an elastic band. In one configuration, the elastic band 90 is made of an electrically insulating material, for example, polyamide or Kapton ™ 96 film. In one configuration, the film 96 is

-19 superimposed in multiple layers, with leads 94 and photoelectric sensors 92 spaced between multiple layers of 96.

[0122] In one configuration, the power supply 54 is also sandwiched between a plurality of dielectric films 96. In one configuration, the power supply 54 also powers the microcontroller 98, which may include one or more of the elements described above, such as signal conditioning assembly 40, RAM 52 memory, DSP 44 processor and RF 46 transmitter. The microcontroller 98 may also be provided with an audible alarm and / or optical status indicator, e.g., an LED, which indicates whether the optical access disconnection / blood leakage detection system 80 are functioning properly.

[0123] Figs. 12 and 13 show one of the operating configurations of the photoelectric system 80. In one configuration, the light emitted by the LED of the photoelectric sensor 92 has a wavelength, for example, in the range from blue to green of the ultraviolet wave spectrum that is absorbed by the color of the blood collected on gas 82. When the light from sensor 92 illuminates the non-blooded, i.e., white gas 82 shown in Fig. 12, a certain percentage of its energy is reflected towards a receiver, e.g. a photocell or phototransistor of a photoelectric sensor 92. In contrast, in Figure 13, blood on gas 82 absorbs most of the light energy emitted from sensor 92, so that sensor 92 detects and receives much less light, for example, the signal is lost. Accordingly, in fig. 13 no arrow is directed from the gauze 82 back to the photoelectric sensor 92 indicating the reflected light.

[0124] In the arrangement shown in Fig. 11, sensors 92a to 92e are spaced relatively large away from access needles 16 and 20, for example, in the order of 2.5 to 7.6 cm (one to three inches) from the needles, so that if the blood reaches sensors 92, it has sufficient distance from the access points to signal access disconnection instead of normal leakage of blood. In addition, the use of multiple sensors 92a to 92e allows some redundancy to be built into the software, e.g., before determining that access has been interrupted, the software searches for several sensors 92 showing no reflection. Alternatively, a single blood detection sensor 92 may be used to indicate access interruption.

[0125] In one embodiment, the at least two concentric rings of optical sensors of different diameters form a sensor system that allows the system to monitor the progress of blood leakage. One of the inner ring sensors (small diameter sensors) is looking for a lack of reflection, which due to the small diameter of the sensor is considered irrelevant. If the next ring (larger diameter) of the sensors does not show a lack of reflected light, then the system recognizes that the leak is not serious. When the leak becomes severe, it reaches into the outer ring of sensors with a larger diameter. The system uses the time between detections in subsequent rings to determine the blood leakage flow. The spacing between the rings makes it possible to assess the volume of blood leakage.

[0126] The microcontroller 98 collects data from the optical sensors 92 and provides this data in a certain configuration via RF signal 58 to the dialysis device 100. The device 100 may include at least one of such components as signal conditioning assembly 10, DSP processor 11 ( which can be provided with built-in RAM and ROM, as well as with other device and functional capabilities as described in this description), which are used for signal analysis 58. In an alternative configuration, the microcontroller 98 includes a signal conditioning assembly, for example

- 20 analog-to-digital converter and / or signal summation circuits that can combine the output signals of each of the photoelectric sensors 92 to obtain one digital signal 58, which is representative of the entire elastic band 90. In another alternative configuration, the software and processing takes place in a microcontroller 98, wherein signal 58 informs the device 100 whether or not there is an interruption in access. And in this case, signal 58 can be continuous, discontinuous, sent only on demand, etc.

[0127] To save power for the power supply 54, the microcontroller 98 in one configuration is kept in a sleep or power saving mode, and the optical sensors 92 are turned off until the dialysis device 100 requests data from the radio link. At this point, the microcontroller 98 "wakes up", activates the light sensors 92, reads signals from the optical receivers of the sensors 92 and passes the status information back to the dialysis device 100. In one configuration, if any of the sensors 92a to 92c does not receive the right amount of light, then the DSP 94 sends a threat signal to the device 100 and at the same time turns on the power of the audible alarm. The device 100 may cause any other appropriate protective action described herein.

Remote electrocardiographic ("ECG") access disconnection sensor [0128] Figures 15, 16, 17 and 18A-18C show various systems for detecting access disconnection using electrocardiographic signals ("ECG"). Generally, an ECG test is a test that measures electrical signals that control a person's heart rhythm. The heart is a muscle pump consisting of four chambers, two upper chambers called atria and two lower chambers called heart chambers. The natural electrical system causes the heart muscle to contract and the heart pumps blood to the lungs and the rest of the body.

[0129] ECG cardiographic electrodes are placed on the patient's skin to detect this natural electrical activity of the heart. In the system 120 of Fig. 15, during the dialysis procedure, the first electrode 122 is attached to the venous line 18, and the second electrode 124 is attached to the patient's skin, e.g., to leg 12a (as shown), arm 12b or chest 12c of patient 12, or alternatively connected to the arterial duct 14. The electrodes 122 and 124 can be connected to the venous line 18 and arterial line 14 through direct contact, capacitive coupling, inductive coupling, wireless or otherwise. Alternatively, a plurality of electrodes 124 may be located at different locations 12a, 12b, 12c of the patient's body 12.

[0130] Figures 18A to 18C show three possible coupling configurations between contacts and blood. In Fig. 18A, the electrode 122 is placed inside the venous line 18 and contacts the blood directly. In Fig. 18B, the electrode 122 is embedded in the wall of venous duct 18 and is coupled with blood, for example, capacitively or inductively. In Fig. 18C, the electrode 122 is mounted outside the venous line 18 and is coupled with blood, similarly, for example, capacitively or inductively. The electrodes can be metal or made of conductive polymer. [0131] In the system 120 of Fig. 15, the blood pump 102 and dialyzer 108 are connected to the arterial line 14 and venous line 18. The extracorporeal circuit also includes other components not shown for ease. Furthermore, the dialyzer 108 communicates with the dialysate source, for example in the form of pouches, or on-line source, with pumps that supply the dialysate to the dialyzer 108, and which are also not shown for ease. The above-mentioned '170 application contains a description of the following

- 21 details of the extracorporeal and dialysate circuits that apply to each of the systems described. The principles of operation of each of the described systems also apply to disconnection of access in hemofiltration and hemodiafiltration systems.

[0132] Electrodes 122 and 124 are electrically connected to a conditioning and signal processing assembly 40, which may include RAM 42 and DSP 44 as mentioned herein. Each of the parts, signal conditioning assembly 40, RAM 42 and DSP 44 may be located locally or remotely as needed, as described herein.

[0133] Electrodes 122 and 124 may, alternatively or additionally, be connected to a device that translates electrical activity into an electrocardiogram, which may exhibit: signs of heart enlargement, signs of insufficient blood supply to the heart, signs of new or previous heart damage (e.g. due to a heart attack), problems with the heart rhythm (arrhythmias), changes in the electrical activity of the heart due to electrolyte imbalance in the body, and signs of inflammation of the sac pericardial. These parameters may be useful during dialysis as described in more detail below.

[0134] Under normal conditions, the natural electrical signals that control the human heart rhythm form the signal 126 shown in Figure 15. After disconnecting the access of the venous line 18 in the configuration shown, the signal 126 stops being detected due to the loss of electrical connection to the body by blood. The device 100 treats the lack of signal 126 as disconnecting access and causes one of the actions described herein to be taken.

[0135] Figs. 16 and 17 show an alternative system 140 and catheter assembly 142 used in system 140, respectively. The system 140 of Fig. 16 uses cardiac catheter access to the chest 12c of patient 12 using cardiac catheter assembly 142. The catheter access assembly 142 provides more direct access to the heart and associated signals than needle access on the patient 126 arm 12. The catheter access assembly 142 may be better suited for acute procedures. Then the physician can more directly monitor the electograms of the blood pool inside the heart and provide more or better information about the functioning of the heart than in the case of typical arterial and venous access, with continuous dialysis of the patient 12.

[0136] The catheter 146 of the assembly 142 is equipped with electrodes, for example electrodes 122 and 124, in any of the configurations shown in Figs. 18A to 18C. The catheter assembly 142 includes arterial 114 and venous access segment which connect to arterial conduit 14 and venous line 18 of the extracorporeal circuit, respectively. The catheter assembly 142 also includes a guide wire 144 for directing the catheter 146 to a desired location, e.g., directly to the patient's heart or to the desired local vein, artery, or transplant.

[0137] In systems 120 and 140, the DSP processor 44 further or alternatively processes the signal

126 and calculates one or more parameters such as changes in heart rate, respiration, stroke volume, cardiac output and central venous blood volume. In addition, a bioimpedance source 130 is connected to the patient, so that the system 120 can perform bioimpedance measurements. Additionally or alternatively, systems 120 and 140 allow injection into the extracorporeal circuit of a solution that is used to stimulate the pace in patients with implanted cardiac rhythm control devices (pacemakers). Systems 120 and 140 allow monitoring of key cardiovascular parameters during dialysis, which can provide a beneficial effect on dialysis treatment or be used for other purposes.

[0138] Bioimpedance, in general, is a measure of changes in the electrical conductivity of the chest or heart. For example, it can be measured based on pulsatile changes in the volume of blood in the aorta. Bioimpedance is important when measuring cardiac output and total circulating blood volume.

[0139] In particular, electrical chest bioimpedance (also called impedance cardiography) has been studied as a non-invasive way to assess cardiac output and other cardiovascular functions. Changes in cardiac output are used as the basis for identifying a change in the patient's hemodynamic state or stating the need for treatment or response to treatment, for example in critically ill patients and in patients at high risk of morbidity and mortality. [0140] Chest bioimpedance has been studied for various indications, including hemodynamic assessment in patients with suspected or diagnosed cardiovascular disease, cardiovascular differentiation and due to pulmonary causes of acute dyspnea, optimization of the atrioventricular interval in patients with atrioventricular sequential pacemakers. and optimization of pharmacotherapy in patients with congestive heart failure.

[0141] Any of the above parameters may be monitored in connection with dialysis or as additional benefits of surgery.

Capacitive Blood Leak Detection System [0142] Figs. 19A and 19B show an alternative blood leak detection device 150 that is wrapped around the patient's arm in any of the ways described above in connection with system 80, and covers access needles 16 and 20. Device 150 contains a matrix of mini-capacitors 152, as best seen in Figure 19A. On both sides of the capacitors are waterproof, for example made of plastic, insulators 154a to 154c. A grounding or shield 156 is provided between the backside of capacitors 152 and back insulator 154c.

[0143] The device 150 does not need to absorb blood to detect blood leakage. The presence of blood under the mini-capacitors 152 causes a change in the electric field surrounding the capacitors. This means that if a moist spot forms under the device 150, the area of ​​capacitors 152 detecting the dielectric change increases. If the area stops growing, the system using the device 150 (which may be any of the remote or wired systems described herein) assumes that a normal leakage has occurred that differs from blood leakage or needle extension. A small leak is a common occurrence when "needle driving" and should not lead to an alarm. If the blood leak increases sufficiently, the system using the device 110 assumes that the access has been partially or completely disconnected and an audible alarm sounds.

Redundant access disconnection / blood leak detection system [0144] Some known systems operate based on detecting access disconnection by identifying an open circuit. One of the problems with these systems is that the sliding of the needle from the patient's body does not always interrupt the electrical circuit. For example, the needle may slide out of the patient's body, but direct the blood stream to the access site from which it came, or to a second needle (e.g. arterial), closing or re-closing the electrical circuit. At the same time, the blood would not return to the patient, but the alarm would not be triggered.

[0145] For other known systems, it is assumed that the extended needle directs the blood stream to a certain portion of the device or system. In this case, if the needle extends completely and quickly from under the device, then the leakage of blood stream to a part of the system may, contrary to the assumption, not occur (or occur insufficiently) and again the alarm may not be triggered.

[0146] To overcome the problems described above, the system of the invention may be used in combination with another of the systems described above or in combination with other types of access disconnection or blood leakage detection systems. In particular, an ejection detection type system may be combined with a blood leak detection system. The optical system 80 is, for example, a blood leak detection system that is particularly effective at detecting blood leaking at an access site. Another type of blood leakage detection system is a conductive jacket or pad that covers the access site in a manner similar to the system 80 of Figures 10 to 14. The conductive jacket or pad includes contacts that form a closed electrical circuit on contact with blood oozing from places of access to the patient's body. An additional blood leakage detection system 150 is described above in connection with Figs. 19A and 19B.

[0147] Overhang detection systems, for example systems with impedance sensors, as described in the '098 and' 480 patents described above, are particularly effective at detecting the full extension of a patient's needle or other access tool. The ultrasonic access disconnection system 10, acoustic systems 60a to 60c and the bioimpedance system 120 are also needle extension detection systems that efficiently detect full extension of the needle.

[0148] Accordingly, it is contemplated to combine each of the blood leak detection and needle projection detection systems into a hybrid or redundant system that efficiently detects any type of error. For example, any of the ultrasonic access disconnection systems 10 and acoustic systems 60a to 60c can be combined with one of the optical systems (system 80), systems with conductive cladding or capacitive systems (device 150) for detecting blood leaks, so that the way does not matter, in which the venous needle was extended. The access disconnection system causes an alarm when the venous needle extends quickly and falls off the patient's body. A blood leak detection system causes an alarm if the venous needle is partially or completely extended and directs the blood stream to the venous or arterial needle.

[0149] It will be apparent to those skilled in the art that various changes and modifications can be made to the preferred embodiments described herein.