Method and apparatus for detecting changes in blood flow in a subject's head

Abstract

A method for detecting changes in blood flow in a subject's head comprises measuring a parameter value of a cardiac bioelectrical signal at a scalp region of the subject relative to a reference cardiac bioelectrical signal. The method further comprises comparing the measured parameter value with a predetermined value of the parameter to determine any changes in blood flow in the subject's head. The determined changes can be used to detect changes in perfusion in the subject's brain, for example, caused by an anticoagulant drug used to dissolve a blood clot in a blood vessel of the subject's brain experiencing an ischemic stroke.

Description

Technical Field

[0001] The present invention relates to apparatus and methods for detecting changes in blood flow in a subject's head.

[0002] The present invention has been developed primarily for use in monitoring patients who are experiencing or are likely to experience changes in head perfusion and will be described hereinafter with reference to this application. However, it will be appreciated that the present invention is not limited to this particular field of use. Background Art

[0003] A stroke is caused by a sudden interruption of blood supply to the brain. In an ischemic stroke, there is a blockage in an artery in the brain that prevents blood from reaching part of the brain.

[0004] CT and / or MRI scans are the most common methods of evaluating blood perfusion in the brain of stroke patients to observe blood perfusion in the brain.

[0005] A CT or MRI scan can detect the presence or relative absence of blood in an area of ​​the body, thereby detecting a blockage (in the case of an ischemic stroke) or a ruptured blood vessel (in the case of a hemorrhagic stroke).

[0006] This scan is also used to monitor blood vessels and thus detect blood perfusion in the brain. In the case of ischemic stroke, it can be used during treatment to assess the effectiveness of anticoagulant drugs delivered to the brain area in dissolving blood clots.

[0007] However, these methods have several limitations. In some cases, the patient needs to be scanned by a CT or MRI machine. CT and MRI machines are expensive and often limited in number. They are often large.

[0008] They also do not provide continuous real-time monitoring of blood perfusion in the brain.

[0009] The present invention seeks to provide a solution which will overcome or substantially ameliorate at least some of the deficiencies of the prior art, or at least provide an alternative.

[0010] It should be understood that if any prior art information is referred to herein, this reference does not constitute an admission that such information forms part of the common general knowledge in the art, in Australia or any other country. Summary of the invention

[0011] In one aspect of the present disclosure, there is provided a method of detecting changes in blood flow in a subject's head, comprising:

[0012] measuring parameter values ​​of a cardiac bioelectric signal in a scalp region of a subject relative to a reference cardiac bioelectric signal;

[0013] The measured parameter value is compared to a predetermined value for the parameter to determine any changes in blood flow in the subject's head.

[0014] The reference cardiac bioelectrical signal may be received by a reference electrode located proximate to the subject's heart.

[0015] The method may further include:

[0016] measuring parameter values ​​of a cardiac bioelectrical signal in a chest region of a subject relative to a reference cardiac bioelectrical signal;

[0017] A ratio of a parameter of the cardiac bioelectric signal measured at the subject's scalp region to a parameter of the cardiac bioelectric signal at the subject's chest region is calculated.

[0018] The method may further include comparing the ratio to a predetermined ratio indicative of an unimpaired blood flow state.

[0019] The method may further include comparing the ratio to a predetermined ratio indicative of an impaired blood flow condition.

[0020] The cardiac bioelectrical signal may be an ECG measurement made in a chest region adjacent to the subject's heart or in a subject's entire chest region.

[0021] Cardiac bioelectrical signals can be represented by a voltage versus time graph.

[0022] The parameter may be the average peak amplitude of a voltage versus time plot.

[0023] The parameter may be indicative of an average peak amplitude of a voltage versus time graph of the measured cardiac bioelectrical signal.

[0024] In another aspect, a headgear device for detecting changes in blood flow in a subject's head is provided, comprising:

[0025] a reference electrode positionable, in use, in a chest region adjacent to a subject's heart;

[0026] a first electrode positionable, in use, over a scalp region of a subject;

[0027] a header cap connected to each of the reference electrode and the first electrode, the header cap comprising:

[0028] A processing unit is configured to measure parameter values ​​of a cardiac bioelectric signal in a scalp area of ​​a subject relative to a reference cardiac bioelectric signal and transmit the parameter values ​​of the cardiac bioelectric signal to a computer configured to determine blood flow changes in the subject's head.

[0029] The headgear device may also include a second electrode configured to be located in the chest area of ​​the subject when in use and configured to receive cardiac bioelectric signals adjacent the heart when in use.

[0030] The processing unit may include a brain-computer interface configured to process cardiac bioelectric signals received from the electrodes and transmit an indication of the cardiac bioelectric signals to a receiver.

[0031] One or more of the reference electrode, the first electrode and the second electrode may be wireless electrodes.

[0032] In another aspect, a system for detecting changes in blood flow in a subject's head is provided, comprising:

[0033] a reference electrode positionable on a chest region of the subject;

[0034] a first electrode positionable at a scalp region of a subject, the first electrode configured to receive a bioelectric signal relative to a reference electrode;

[0035] a second electrode positionable in use in a chest region of a subject and configured to receive cardiac bioelectrical signals proximal to the heart relative to a reference electrode;

[0036] a head cap connected to each of the reference electrode and the first electrode, the head cap comprising:

[0037] A processing unit configured to measure parameter values ​​of a cardiac bioelectric signal received at a scalp region of the subject relative to a reference cardiac bioelectric signal received at a chest region of the subject, and to transmit the parameter values ​​of the cardiac bioelectric signal to a computer configured to determine blood flow changes in the subject's head.

[0038] The processing unit may be a brain-computer interface.

[0039] The system may further include a receiver to receive the transmitted cardiac bioelectrical signal. The receiver may be a wireless receiver.

[0040] One or more of the reference electrode, the first electrode and the second electrode may be wireless electrodes.

[0041] In another aspect, a method for detecting changes in blood flow in a head of a subject is provided, comprising:

[0042] Provide headgear equipment;

[0043] positioning a reference electrode in a chest region adjacent to the subject's heart;

[0044] positioning a first electrode in a scalp region of the subject;

[0045] positioning a second electrode in the chest region of the subject;

[0046] Obtaining a reference cardiac bioelectrical signal;

[0047] obtaining a cardiac bioelectrical signal from a scalp region of the subject;

[0048] The obtained reference cardiac bioelectrical signal and the obtained cardiac bioelectrical signal of the subject's scalp area are transmitted to a processor configured to determine blood flow changes in the subject's head.

[0049] The processor may be configured to determine a change in blood flow in the subject's head according to a method of detecting a change in blood flow in the subject's head.

[0050] The present invention may also broadly consist of the parts, elements and features mentioned or indicated individually or collectively in the specification of the present application, as well as any or all combinations of any two or more than two of the parts, elements or features, and when specific integers having known equivalents in the field to which the present invention relates are mentioned herein, such known equivalents are deemed to be included herein as if set forth individually.

[0051] Other aspects of the invention are also disclosed. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Although any other forms may fall within the scope of the present invention, embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0053] Figure 1 is a schematic diagram of a headgear device according to an embodiment of the present invention; and

[0054] Figure 2 Shows the procedures and results of experiments performed using artificially generated EMS signals.

[0055] FIG. 3 is a graph showing the average cardiac biosignal amplitude before and after anaerobic exercise and the average amplitude before and after anaerobic exercise.

[0056] Figure 4 shows the percentage of scalp heart biosignal amplitude to chest heart biosignal amplitude before and after anaerobic exercise picture.

[0057] Figure 5 is a representation of a cardiac bioelectric signal according to an embodiment of the present invention.

[0058] Figure 6 is a perspective view of a headgear device according to an embodiment of the present invention.

[0059] Figure 7 is a perspective view of a headgear device according to another embodiment of the present invention. DETAILED DESCRIPTION

[0060] The heart generates the largest electrical signals in the body. Blood is one of the most conductive components in the body and therefore provides a major pathway for electrical signal propagation. Applicants have discovered that reduced cerebral blood flow (CBF) or blood flow through a subject's head will reduce this propagation and therefore reduce the amplitude of extracerebral electrical signals sensed in a region of the subject's head, such as across the scalp. The extracerebral electrical signal may be a cardiac bioelectrical signal or a bioelectrical signal generated by the subject's heart. The extracerebral bioelectrical signal may be another bioelectrical signal. The extracerebral bioelectrical signal may be the result of an artificially generated stimulus, such as an artificially generated muscle electrical stimulation.

[0061] Figure 1 An example of a headgear device 100 that can be used to detect changes in blood flow in a subject's head is shown. In this embodiment, the extracerebral bioelectrical signals are cardiac bioelectrical signals. It is foreseeable that in other embodiments, other types of extracerebral bioelectrical signals may be used. The headgear device includes an EEG headset configured to record EEG signals, and scalp electrodes operably coupled to the EEG headset and configured to receive and record bioelectrical signals, such as brain and extracerebral bioelectrical signals.

[0062] The head cap device senses cardiac bioelectrical signals proximal to the heart (e.g., in the chest area of ​​the subject) and proximal to the head (e.g., in the scalp of the subject). This information is sent to a processing unit in the head cap 40, which then transmits the information to a receiver. The receiver sends the information to a computer including a processor. The processor can process the information by executing an algorithm to determine any blood flow changes in the subject's head. The computer can be remote from the head cap device or be part of the head cap device. The processor in the computer can then display the received signals and / or an indication of the determined blood flow changes on a display.

[0063] like Figure 1 As shown, in use, the reference electrode 10 is located on the left side of the patient's chest (adjacent to the heart). The first electrode or first recording electrode 20 is located on the scalp area of ​​the subject. The first electrode 20 can be located at any location on the scalp area of ​​the subject. For example, the first electrode can be located at a location on the scalp area defined by the international 10-20 system for applying scalp electrodes in EEG examinations.

[0064] The first electrode 20 senses a cardiac bioelectric signal at the subject's head region or scalp relative to a reference signal sensed by the reference electrode 10. Applicants have discovered that by placing the reference electrode 10 near the patient's heart, such as in the patient's chest region, and recording electrical activity in the patient's scalp region with the first electrode 20, a component of the heart-related electrical activity at the scalp (cardiac bioelectric activity in the subject's scalp region) is evident or can be easily detected.

[0065] like Figure 1As shown, the second recording electrode 30 is placed on a region of the patient's chest proximate to the reference electrode 10. Applicants have discovered that the signal recorded by the second electrode relative to the reference signal when the heart is pumping blood indicates the bioelectrical activity proximate to the subject's heart.

[0066] Figure 6 Display usage Figure 1 1 shows a reading of a cardiac bioelectric signal obtained by a headgear device according to one embodiment of the present invention. Each of AF3, T7, Pz and AF4 represents the location of a recording electrode 30 at the subject's scalp region. T8 represents a recording electrode placed at the subject's chest region, similar to the second electrode 30 described above. Figure 6 In FIG. 1 , the sensed cardiac bioelectrical signal is represented by a voltage versus time diagram, where the voltage represents the relative strength of the signal. It can be seen that the voltage versus time diagram representing the cardiac bioelectrical signal of electrode T8 has the highest peak amplitude because it is closest to the source of cardiac electrical activity.

[0067] A method of detecting blood flow changes in a subject's head includes measuring a parameter value of a cardiac bioelectric signal at a scalp region of the subject relative to a reference cardiac bioelectric signal.

[0068] For example, the parameter of the cardiac bioelectric signal may be the average peak amplitude of the signal.

[0069] Figure 5 The voltage versus time signals from each of the electrodes AF3, T7, Pz, and AF4 shown in are examples of cardiac biopotential signals obtained in the subject's head region relative to the signal received by a reference electrode located in the subject's chest region.

[0070] exist Figure 5 In the embodiment of the present invention, the parameter is the amplitude of a voltage versus time graph representing the cardiac bioelectrical signal. Advantageously, the cardiac bioelectrical signal has distinct, repetitive features corresponding to the electrical activity required to repeatedly contract the heart over time.

[0071] The method also includes comparing the measured parameter value to a predetermined value for the parameter to determine any changes in blood flow in the subject's head.

[0072] If the parameter is an average peak amplitude, the predetermined value of the parameter may be an average peak amplitude in the same region where the first electrode is located, which average peak amplitude is recorded when blood flow to the patient's head is not impaired. For example, if the patient's brain blood flow is impaired compared to when the predetermined value was measured, the measured average peak amplitude value will be lower than the predetermined average peak amplitude value for the patient.

[0073] Because cardiac bioelectric activity can be patient-specific, a ratio of a parameter of a cardiac bioelectric signal measured at a subject's scalp region to a parameter of a cardiac bioelectric signal at a subject's chest region can be calculated. For example, the average peak amplitude of the cardiac bioelectric signal recorded by a first electrode relative to a reference electrode can be divided by the average peak amplitude of the cardiac bioelectric signal recorded by a second electrode relative to the reference electrode. The ratio can be compared to a predetermined ratio to determine whether any changes in head blood flow have occurred in the subject. For example, the predetermined ratio can indicate a general subject with unimpaired head blood flow. Alternatively, the predetermined ratio can indicate the degree to which the subject's head blood flow is unimpaired.

[0074] This method can be used to continuously monitor a patient to detect any changes in blood flow in the patient's brain over time. For example, during an ischemic stroke, a blood clot is present in the blood vessels of the brain, which impairs blood flow in the brain. Using this method, when a blood clot persists in the blood vessels, the peak amplitude of the cardiac bioelectric signal measured in the subject's head region will be relatively low. If a drug is administered to the patient to dissolve the blood clot, the method and head cap device can be used to determine whether the blood clot has been dissolved and whether blood flow in the brain has increased relative to before the drug was administered.

[0075] If the blood clot is successfully dissolved, the cardiac bioelectrical signals measured in the subject's head region will be relatively higher than those measured when the blood clot is present in the blood vessel. The method and head cap can also be used in a variety of applications where monitoring blood flow in the subject's brain is beneficial. For example, the method can be used to monitor conditions related to impaired blood flow in the brain, such as delirium or traumatic brain injury.

[0076] Figure 6 An embodiment of a headgear device for detecting changes in blood flow in a subject's head is shown.

[0077] The headgear device 200 includes a wearable headgear that can be worn on the head of a user. A reference electrode 210 extends from the headgear and can be positioned and applied to a chest region of the subject adjacent to the heart. Thus, when in use, the reference electrode 210 can be positioned on a chest region of the subject adjacent to the heart. One or more electrodes 220 can be positioned on a scalp region of the subject. One of the electrodes 220 can be a first electrode. The electrodes 220 can be positioned throughout the major cerebral vascular region to optimize monitoring of changes in cerebral blood flow.

[0078] The headgear device 200 is a wireless, portable EEG headset.

[0079] The headgear device includes a second electrode 230 configured to be located in the chest region of the subject in use and configured to receive cardiac bioelectrical signals adjacent the heart in use.

[0080] Each electrode 220 is configured to sense and conduct bioelectrical signals when applied to the body and headgear device, in use.

[0081] Each of the reference electrode 210, the one or more electrodes 220, and the second electrode 230 is a scalp electrode operably connected to the EEG headset to sense and receive bioelectric signals and transmit the bioelectric signals to the EEG headset.

[0082] Each electrode 220 may be a dry electrode or a semi-dry electrode.

[0083] The headgear device 200 includes a processing unit (not shown) for receiving bioelectric signals from each of the electrodes 210, 220, 230. The processing unit (not shown) is configured to measure parameter values ​​of the cardiac bioelectric signals recorded in the subject's scalp region relative to the reference cardiac bioelectric signals obtained by the reference electrode, and transmit the parameter values ​​of the cardiac bioelectric signals to a remote computer, which is configured to determine blood flow changes in the subject's head according to the above method.

[0084] For example, a processing unit (not shown) in the headgear device 200 receives bioelectric signals from each of the electrodes 210, 220, 230 and transmits the cardiac bioelectric signals to a receiver outside the headgear device. In an embodiment, the processing unit may include a brain-computer interface, such as a BCI board, which includes a microcontroller for on-board processing of the cardiac bioelectric signals received from the electrodes. The BCI board can then send the processed cardiac bioelectric signals to the receiver.

[0085] This processed information can be sent to a receiver of a remote computer (not shown). The remote computer (not shown) can use an algorithm for detecting changes in blood flow in the subject's head according to embodiments of the above methods. The skilled person will appreciate that there are a variety of ways to implement embodiments of the above methods.

[0086] exist Figure 6 In the embodiment shown, the head cap device 200 includes a comb portion 270 to clean the hair on the forehead of the user wearing the head cap. This will expose the scalp and allow the electrodes to better contact the scalp. The head cap device 200 includes a curved portion 280, which extends over the user's head when in use. The head cap device 200 includes an elastic band 290, which extends around the user's head when in use. The electrodes 220 are arranged on the lower side of the curved portion 280 and the band. The band 290 is elastic so that it can be securely fitted around heads of different sizes and shapes. The elastic band 290 and the curved portion 280 are configured to fit tightly around the patient's head to ensure sufficient contact between the electrodes and the user's scalp, thereby producing precise results.

[0087] The ear hook 260 is configured to fit around the ear of the user when the headgear device is placed on the user. The ear clip 240 includes the reference electrode 210. The ear clip 240 can be clipped on the ear to use the ear clip as a reference electrode instead of the reference electrode 210.

[0088] Figure 7 Another embodiment of a headgear device is shown. The headgear device 300 has an elastic band 390 that includes an electrode 320. The headgear device 300 has an ear clip 340 that can be used as a reference electrode. The headgear device 300 has a reference electrode 310 that can be located in the chest area of ​​the user adjacent to the user's heart and an electrode 330 that can be located on the chest of the user.

[0089] The headgear device 200 and / or 300 can also provide EEG-only functionality by changing the location of the reference electrode 210 from near the heart to another known reference location, or by changing the reference method to the method used to acquire the EEG. In one embodiment, the reference electrode can be placed on the mastoid bone and the first and second electrodes moved to other recording locations, such as locations for EEG electrodes identified by the international 10-20 system.

[0090] In other embodiments, the headgear device may include one or more of a variety of sensors such as an accelerometer, a temperature sensor, a blood oxygen sensor, an ambient noise sensor, and a quantitative EEG.

[0091] In addition to the cardiac bioelectrical signals at the scalp relative to a reference cardiac bioelectrical signal adjacent to the user's heart, parameters measured by the headgear device may include:

[0092] 1) Quantitative EEG (qEEG) measurements such as the delta / alpha ratio (DAR).

[0093] 2) Cardiac electrical signals and / or artificially generated electrical signals.

[0094] 3) Environmental (auditory and visual noise) evoked potentials.

[0095] 4) Accelerometer. The headset may have a built-in accelerometer to monitor the user's head movement in addition to changes in fluid flow due to pulsatile perfusion events in the head.

[0096] 5) Temperature sensor. The headset may have an infrared temperature sensor to monitor the patient’s temperature.

[0097] 6) Blood oxygen, via a built-in oximeter, such as a near infrared (NIR) sensor or near infrared spectroscopy (NIRS) or a green light pulse oximeter.

[0098] The above sensors may be included in a headgear device.

[0099] Therefore, headgear devices can be used to:

[0100] 1) Monitor changes in electrical signal strength at and across the skull as a method of inferring changes in head blood flow. The signal can be cardiac and / or artificially generated (e.g., EMS or proprietary signal generators). Cardiac signals can also be used to assess cardiac physiology and monitor heart rate.

[0101] 2) Monitor environmental stimuli that affect the brain, especially light and auditory stimulation, with reference to relevant cortical evoked potentials as a means of real-time monitoring of changes in brain function and cortical sensitivity.

[0102] 3) Combined with standard EEG measurements, the aforementioned methods can be used to monitor brain function in real time, particularly changes in the delta:alpha signal ratio over time, and have the potential to detect and monitor perfusion changes, seizures, delirium, and intracranial pressure.

[0103] 4) Monitoring relative signal strength between electrodes can be used to map ischemic areas, changes due to treatment, vasospasm / delayed cerebral ischemia, long-term injury, and potential changes during recovery.

[0104] 5) Monitor head movement (via accelerometer), whether due to gross patient movement or changes in fluid flow due to pulsatile perfusion events in the head. Temperature and blood oxygenation (NIR / green light pulse oximeter) will also be monitored.

[0105] It is contemplated that in embodiments other than that shown, wireless electrodes may be used.

[0106] The headgear device 200, 300 can be used for continuous or semi-continuous monitoring of blood flow in the brain. The headgear device 200, 300 can be a low voltage-low power wireless electronic device, thereby causing low electrical safety risks.

[0107] Embodiments of the headgear apparatus and methods may be used in many other applications, including nursing assessment, emergency medicine, delirium, traumatic brain injury, epilepsy, intracranial pressure monitoring, and neurorehabilitation.

[0108] The method of monitoring changes in blood flow in a subject's head would allow a doctor or nurse to quantitatively monitor a stroke patient between CT / MRI scans. This would allow real-time monitoring of stroke treatment, providing information about treatment outcomes that would help guide subsequent steps in patient management. If treatment is unsuccessful, the device would be able to alert clinicians more quickly than current methods, allowing the patient to receive secondary treatment if needed.

[0109] The method and headgear device for detecting changes in blood flow in a subject's head can also be used to detect vasospasm / delayed cerebral ischemia in patients who have experienced a subarachnoid hemorrhage. These patients can be tested continuously to detect the onset of vasospasm or decompression sickness (DCI). Transcranial Doppler ultrasound is the current method used to detect vasospasm, but it is not a continuous method and is sometimes not very accurate. New rapid and accurate methods for detecting vasospasm / DCI will allow patients to receive treatment more quickly than existing detection methods. This can prevent irreversible damage that vasospasm / DCI can cause.

[0110] The method and headgear device for detecting changes in blood flow in a subject's head may also be used to monitor epilepsy, delirium, traumatic brain injury, intracranial pressure, and neurorehabilitation.

[0111] In another embodiment, the headgear device may be part of a "smart helmet" that may be used to monitor wakefulness states in occupations where hard hats are typically used.

[0112] Monitoring cardiac bioelectric signals on the patient's head can also be used to assess cardiac physiology and monitor heart rate. Any changes in cardiac signals during exercise can inform the patient's cardiac physiology.

[0113] Lab Report

[0114] An experiment was conducted to test the following hypothesis:

[0115] The heart generates the largest electrical signals in the body, and blood is one of the most conductive components in the body, thus providing a major pathway for electrical signal propagation. It can be expected that reduced cerebral blood flow will reduce this propagation, thereby reducing the amplitude of the heart's electrical signals recorded across the scalp compared to the amplitude of the heart's electrical signals recorded at the chest. It can be expected that increased cerebral blood flow will increase this propagation, thereby increasing the amplitude of the heart's electrical signals recorded across the scalp compared to the amplitude of the heart's electrical signals recorded at the chest. This method can be used to monitor patients suffering from stroke, sleep apnea, delirium, traumatic brain injury, or other diseases associated with impaired cerebral blood flow.

[0116] By repositioning the reference electrode of the EMOTIV Insight EEG headset to the left chest, the cardiac bioelectric signals on the EEG scalp electrodes are detected. The scalp electrode T8 is repositioned to the right chest to record the Figure 1 The applicant studied how anaerobic exercise-induced reduction in CBF (via push-ups) affects the amplitude of cardiac bioelectric signals and EMS signals (using the OpenBCI EEG headset) across the scalp ( Figure 2). The applicant also studied how it affects the percentage of the scalp cardiac bioelectric signal amplitude to the chest cardiac bioelectric signal amplitude.

[0117] result: One minute after anaerobic exercise, the amplitude of the cardiac biosignal at the scalp electrode and the amplitude of the signal induced by EMS both decreased (P<0.05). The signal amplitude returned to the baseline after 5 minutes (Figure 3). One minute after anaerobic exercise, the percentage of the scalp cardiac biosignal amplitude to the chest cardiac biosignal amplitude also decreased. Then after 4 minutes, it increased to the baseline (Figure 4).

[0118] The observed reductions in the amplitude of cardiac biosignals and EMS signals across the scalp, as well as the percentage of scalp cardiac biosignal amplitude to chest cardiac biosignal amplitude, may be caused by the reduction in CBF (cerebral blood flow) induced by anaerobic exercise. The EMS signal is a control stimulus because it is not related to cardiac physiology. These findings provide preliminary evidence that a reduction in CBF can be detected by a reduction in extracerebral electrical signals recorded across the scalp.

[0119] Control experiment

[0120] The above method is based on the assumption that changes in blood flow alter the propagation of electrical signals. This assumption was tested using artificially generated electrical signals (generated by an electrical muscle stimulation (EMS) device). The EMS signal was measured as a control because its generation is independent of the user's physiology.

[0121] Place the EMS pad on your upper back. Set the stimulation to a constant frequency. Figure 2 As shown, the electrical signals generated are recorded using an EEG headset.

[0122] Measuring scalp electrical activity using an OpenBCI EEG headset to record EMS signals showed that there were characteristics of artificially generated electrical signals in the head electrical activity measured near the subject's scalp.

[0123] Implementation plan:

[0124] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the phrases "in one embodiment" or "in an embodiment" appearing in various places throughout this specification do not necessarily refer to the same embodiment, although they may be the same. Furthermore, as will be apparent to one of ordinary skill in the art from this disclosure, in one or more than one embodiment, the particular features, structures, or characteristics may be combined in any suitable manner.

[0125] Similarly, it should be understood that in the above description of exemplary embodiments of the present invention, various features of the present invention are sometimes combined in a single embodiment, figure, or description thereof for the purpose of simplifying the disclosure and aiding in the understanding of one or more various inventive aspects. However, this method of disclosure should not be interpreted as reflecting the intention that the claimed invention requires more features than those expressly recited in each claim. On the contrary, as reflected in the following claims, inventive aspects lie in less than all features of a single aforementioned disclosed embodiment. Therefore, the claims following the detailed description of the specific embodiments are hereby expressly incorporated into the detailed description of the specific embodiments, wherein each claim independently represents a separate embodiment of the present invention.

[0126] In addition, although some embodiments described herein include some features that do not include other features in other embodiments, as will be understood by those skilled in the art, the combination of features of different embodiments is intended to be within the scope of the present invention and to form different embodiments. For example, in the following claims, any claimed embodiment may be used in any combination.

[0127] Specific details

[0128] In the description provided herein, many specific details are set forth. However, it should be understood that embodiments of the present invention can be implemented without these specific details. In other cases, well-known methods, structures and techniques are not shown in detail to avoid obscuring the understanding of this specification.

[0129] Contains and includes

[0130] In the following claims and in the foregoing description of the invention, except where the context requires due to explicit language or necessary implication, the word "comprise" or variations thereof are used in an inclusive sense, i.e. indicating the presence of stated features but not excluding the presence or addition of other features in various embodiments of the invention.

[0131] Any term used in this article: including or including is also an open term, which also means at least including the elements / features following the term, but not excluding other elements / features. Therefore, including is synonymous with including.

[0132] Scope of the Invention

[0133] Thus, while the embodiments considered to be the present invention have been described, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the present invention, and it is intended that all such changes and modifications fall within the scope of the present invention. For example, any of the schemes given above are merely representative of procedures that may be used. Functions may be added or deleted from the block diagrams, and operations may be interchanged between functional blocks. Steps may be added or deleted from the described methods within the scope of the present invention.

[0134] Although the invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims

1. A method for detecting changes in blood flow in a subject's head, comprising: measuring a value of a parameter of a cardiac bioelectrical signal received by a first electrode located in a scalp region of the subject relative to a reference cardiac bioelectrical signal received by a reference electrode located adjacent to the subject's heart; measuring a value of a parameter of a cardiac bioelectrical signal received by a second electrode located in a chest region of the subject relative to a reference cardiac bioelectrical signal; calculating a ratio of a value of a parameter of a cardiac bioelectric signal measured at a scalp region of the subject relative to a reference cardiac bioelectric signal to a value of a parameter of a cardiac bioelectric signal measured at a chest region of the subject relative to the reference cardiac bioelectric signal; and The calculated ratio is compared to a predetermined ratio to determine any changes in blood flow in the subject's head.

2. The method according to claim 1, further comprising: The calculated ratio is compared to a predetermined ratio indicative of an unimpaired blood flow state.

3. The method according to claim 1, further comprising: The calculated ratio is compared to a predetermined ratio indicative of an impaired blood flow condition. 4 . The method of claim 1 , wherein the reference cardiac bioelectrical signal is an ECG measurement made in a chest region adjacent to the subject's heart or in an entire chest region of the subject.

5. A system for detecting changes in blood flow in a subject's head, comprising: a reference electrode positionable on a chest region of the subject; a first electrode positionable at a scalp region of the subject, the first electrode configured to receive cardiac bioelectrical signals relative to a reference electrode; a second electrode positionable in use in a chest region of a subject and configured to receive cardiac bioelectrical signals proximal to the heart relative to a reference electrode; a header cap connected to each of the reference electrode and the second electrode, the header cap comprising: A processing unit configured to measure values ​​of a parameter of a cardiac bioelectric signal received at a scalp region of the subject relative to a reference electrode and values ​​of a parameter of a cardiac bioelectric signal of a heart adjacent to the reference electrode received at a chest region of the subject, calculate a ratio of the values ​​of the parameter of the cardiac bioelectric signal measured at the scalp region of the subject relative to the reference electrode to the values ​​of the parameter of the cardiac bioelectric signal of a heart adjacent to the reference electrode measured at the chest region of the subject, and compare the calculated ratio with a predetermined ratio to determine any change in blood flow in the head of the subject.

6. The system of claim 5, wherein the processing unit is a brain-computer interface.

7. The system according to claim 5, further comprising a receiver to receive the transmitted cardiac bioelectrical signal, wherein the receiver is a wireless receiver.

8. The system of claim 5, wherein one or more of the reference electrode, the first electrode, and the second electrode is a wireless electrode.

9. A method of detecting changes in blood flow in a subject's head, comprising: measuring a value of a parameter of a cardiac bioelectric signal in a scalp region of the subject relative to a reference cardiac bioelectric signal, wherein the reference cardiac bioelectric signal is received by a reference electrode located adjacent to the subject's heart; measuring a value of a parameter of a cardiac bioelectrical signal received by an electrode located in a chest region of the subject relative to a reference cardiac bioelectrical signal; wherein the parameter is indicative of an average peak amplitude of a voltage versus time graph of the measured cardiac bioelectrical signal; calculating a ratio of a value of a parameter of a cardiac bioelectric signal measured at a scalp region of the subject relative to a reference cardiac bioelectric signal to a value of a parameter of a cardiac bioelectric signal measured at a chest region of the subject relative to the reference cardiac bioelectric signal; and The calculated ratio is compared to a predetermined ratio to determine any changes in blood flow in the subject's head.

10. The method according to claim 9, further comprising: The calculated ratio is compared to a predetermined ratio indicative of an unimpaired blood flow state.

11. The method according to claim 9, further comprising: The calculated ratio is compared to a predetermined ratio indicative of an impaired blood flow condition.

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