Method of non-invasively obtaining information of intracranial pressure of a patient

Abstract

In a method of non-invasively obtaining information on intracranial pressure of a patient, during a first time period, a plurality of facial veins of the patient are occluded by applying external pressure to each of the plurality of facial veins, which emanate from the periorbital region. During the first time period, external pressure is applied to a designated vein (17) connected to an intracranial vessel at a location within the region, upstream of the occlusion of the plurality of facial veins. Changes in the geometry of the designated vein (17) caused by the external pressure are observed to obtain at least one first value related to venous pressure in the designated vein (17). The at least one first value is processed to obtain information on intracranial pressure. The method enables measuring pressure values that are closely related to intracranial pressure without the need for measurements within the intracranial space. Instead, an occlusion establishes a direct pressure communication between the intracranial vessel and the designated vein, which can be easily examined outside the head.

Description

Technical Field

[0001] This invention relates to a method and system for non-invasively obtaining information about a patient's intracranial pressure. Background Technology

[0002] Intracranial pressure (ICP) is the pressure exerted by the contents of the cranial cavity (especially cerebrospinal fluid) on the walls of the cranial cavity and brain tissue. Normal ICP in a supine adult is 5 to 15 mm Hg, with an acceptable maximum of approximately 20-25 mm Hg. ICP exceeding these values ​​(i.e., increased intracranial pressure), such as due to a traumatic event, indicates a medical emergency, as elevated pressure can cause headache, ataxia, confusion, drowsiness, coma, and even death. Therefore, treatment is necessary to lower ICP.

[0003] Reliably, ICP can only be measured invasively by drilling a hole in the skull to insert a pressure probe, or by puncturing the cerebrospinal fluid cavity within the dural sac, a procedure known as lumbar puncture.

[0004] Several non-invasive methods for measuring ICP have been proposed, see SJ Müller et al., “Non-Invasive Intracranial Pressure Monitoring,” J. Clin. Med. 2023, 12, 2209. One of these methods, particularly discussed in US 9,585,578 B2 (Third Eye Diagnostics, Inc.) and WO 2004 / 100770 A2 (Caritas St. Elizabeth's Medical Center of Boston, Inc.), is based on applying external force to the eye and imaging the central retinal vein using techniques such as Doppler ultrasound. The collapse of the vein causes occlusion, stopping blood flow, which can be observed from the Doppler signal. Although these methods can be performed through closed eyelids, Doppler ultrasound examination has a significant impact on the delicate tissues of the eye and surrounding area. This is why the acoustic output exposure levels used in ophthalmology are strictly limited, and why conventional Doppler techniques cannot be applied indiscriminately to the ocular region. Furthermore, to obtain ICP, the external pressure value applied to occlude the central retinal vein needs to be adjusted to account for intraocular pressure (IOP). This introduces further problems and complicates the process. Summary of the Invention

[0005] The purpose of this invention is to create a method for obtaining information about a patient's intracranial pressure that is non-invasive, reliable, and has minimal impact on the patient.

[0006] The technical solution of the present invention is defined by the features of claim 1. According to the present invention, the method includes the following steps: a) During a first time interval, the multiple facial veins leading out of the periorbital region are blocked by applying external pressure to each of the patient's multiple facial veins; b) During the first time interval, in the region, at a location upstream of the blockage of the plurality of facial veins, external pressure is applied to a designated vein connected to an intracranial vessel; c) Observe the changes in the geometry of the designated vein caused by the external pressure to obtain at least one first value related to the venous pressure in the designated vein; d) Process the at least one first value to obtain information about the intracranial pressure.

[0007] Blocking facial veins prevents blood from leaking out of the eye socket and disrupts pressure equalization in the area. Therefore, blockage involves preventing both blood leakage and pressure equalization; complete occlusion of the corresponding vessel is not necessary, but reducing its cross-sectional area by 80% or more, particularly 90% or more, may be sufficient. Since the veins in this area communicate with intracranial vessels (such as the cavernous sinus), and the internal pressure of the cavernous sinus is directly affected by ICP, a essentially closed system is achieved after blockage. This closed system includes the intracranial vessels and the veins in the area, which can be easily examined externally. This contrasts with intracranial vessels such as the cavernous sinus, central retinal vein, or similar vessels.

[0008] When blocking facial veins, it is not necessary to block all the blood vessels that originate from that area. Blood vessels with very small cross-sectional areas do not significantly cause overflow or pressure equalization, so they do not need to be blocked in order to create a essentially closed system.

[0009] Measurements in healthy volunteers showed that the relevant blood vessel could be blocked by applying an external pressure of only 20 mm Hg. Given that ICP does not exceed 50 mm Hg, applying an external pressure of approximately 55 mm Hg or higher, particularly 55–70 mm Hg, would be sufficient to ensure blockage. This pressure has been found to be well tolerated in healthy volunteers, and it is presumed that it will be tolerable in most patients as well.

[0010] A system for non-invasively obtaining information about a patient's intracranial pressure, comprising: a) A pressure applicator for blocking the multiple facial veins that originate from the periorbital region by applying external pressure to each of the multiple facial veins of the patient; b) An imaging probe for observing, within the region and upstream of the site of occlusion of the plurality of facial veins, changes in the geometry of a designated vein caused by external pressure applied to a designated vein connected to an intracranial vessel; and c) A processor for processing at least one first value related to venous pressure in the designated vein, the at least one first value being obtained from observed changes in geometry to obtain information about the intracranial pressure.

[0011] The purpose of the pressure applicator is to simultaneously block blood flow in multiple facial veins. For this, the appropriate pressure between the applicator and the patient's skin is in the range of 60-100 mmHg. Even at a high ICP value of approximately 50 mmHg, the relevant facial veins are ensured to be blocked. Simultaneously, the patient can tolerate this applied pressure well.

[0012] In some implementations, the pressure applicator may have the additional function of guiding and / or supporting the imaging probe. This simplifies the measurement process for the operator and improves the consistency of imaging probe positioning if the designated vein needs to be repeatedly examined at the location. The pressure applicator and / or probe may have guiding elements or guiding surfaces designed to interact to provide reliable guidance or positioning of the probe relative to the pressure applicator.

[0013] The processor runs software to instruct the system to perform the methods of the present invention. This corresponding software is another subject of the invention. The software can run on an imaging probe, a separate unit connected to the imaging probe via a wired or wireless connection, and / or a remote server. Typically, the software controls the imaging probe to generate images of a designated vein and surrounding tissue, processes the images (e.g., for contrast enhancement or edge detection), processes other sensor data, such as data from a pressure sensor indicating external pressure applied to the designated vein, and processes the at least one first value to obtain information about intracranial pressure.

[0014] This invention enables non-invasive measurement of ICP or related quantities, reducing the risk of complications such as infection, hemorrhage, or brain or spinal cord injury.

[0015] Furthermore, compared to other non-invasive methods, this invention enables the measurement of pressure values ​​closely related to intracranial pressure without requiring measurement within the intracranial space. Instead, occlusion establishes a direct pressure transmission between the intracranial vessel and a designated vein that is easily accessible outside the head. The occlusion prevents blood from spilling out or causing pressure equalization through other vessels in the venous system, which is particularly critical when ICP is elevated above normal levels. Therefore, examination can be performed more easily outside the intracranial space. Additionally, the patient burden is reduced, for example, by not affecting sensitive intracranial structures such as the central retinal nerve. Because these structures are unaffected, there are less stringent limitations on imaging parameters such as energy or frequency, allowing for imaging with better resolution and / or contrast, thus improving the accuracy and reliability of the measurement. Another advantage is the small distance between the skin and the designated vein, meaning that the required penetration depth for the imaging modality is small, and the negative impact of the tissue layer between the probe and the vein is minimized.

[0016] The systems and methods of this invention are suitable for long-term ICP monitoring over periods of weeks to months. The information obtained regarding disease progression and patient recovery improves patient care. Furthermore, the systems and methods of this invention improve the accessibility of ICP monitoring due to their non-invasiveness and simplicity. This invention can be implemented in pre-hospital settings, thereby enabling more effective patient screening and faster clinical decision-making.

[0017] In a preferred embodiment, during a second time interval, before and / or after the first time interval, external pressure is applied to a designated vein at the location, and changes in the geometry of the designated vein caused by the external pressure are observed to obtain at least one second value related to venous pressure. This is because the at least one first value is obtained in a scenario where multiple facial veins are blocked, while the at least one second value is obtained in a scenario where multiple facial veins are not blocked. Therefore, the at least one second value provides a reference value in the absence of a closure system including the designated vein and intracranial vessels at the measurement location.

[0018] Similarly, unblocking does not require completely removing the external pressure applied by the pressure applicator to each of the multiple facial veins, but rather requires restoring the available cross-sectional area to at least 80% or more, especially 90% or more, of the free cross-sectional area.

[0019] In this preferred embodiment, both the at least one first value and the at least one second value are used to obtain information about intracranial pressure.

[0020] In a preferred embodiment, the intracranial pressure (ICP) value is determined by the at least one first value ( p obs ) and the at least one second value (p nonobs The difference between the values ​​is obtained, specifically from a set of first and second values ​​obtained from a series of near real-time measurements. This is based on the assumption that the at least one second value represents a reference value for an "open" system, while the higher pressure according to the at least one first value is caused by intracranial pressure, and in the currently closed system, the effect of ICP effectively increases the baseline pressure.

[0021] In this implementation, the intracranial value (ICP) can be calculated, for example, as follows:

[0022] Where Δ p The pressure difference Δ between veins represents the pressure difference between veins. p ,

[0023] in p nonobs This represents the occlusion pressure under unobstructed conditions, while p obs This indicates the occlusion pressure in cases of facial vein obstruction.

[0024] Because intracranial vessels (such as the cavernous sinus) are affected by cerebrospinal fluid and, consequently, by intracranial pressure (ICP), the higher the intracranial pressure, the greater the pressure difference between the two states. However, even when ICP is zero, pressure increases due to the reduced cross-sectional area of ​​veins. Therefore, the empirical factor k also plays a role. It must be determined experimentally and can vary significantly depending on the chosen vein. Preliminary experiments suggest that a k value may be close to 1, at least if the chosen vein is the nasofacial vein or its lateral branches (particularly near the confluence with the nasofacial vein), and if the measurement is taken at the root of the nose (see below).

[0025] In addition to multiplying by a constant k, more complex functions can be used to determine the ICP from the pressure difference between veins. Another advantage of calculating the ICP from the pressure difference between veins is that a constant pressure offset, which depends on the zero reference point used to measure the external pressure, affects both the first and second values ​​in the same way and cancels each other out when calculating the pressure difference.

[0026] In clinical practice, ICP measurements are typically zeroed to atmospheric pressure and leveled to the external auditory canal when the patient is supine and to the glabella (midline between the eyebrows) when the patient is in a strict lateral decubitus position, corresponding to the level of the interventricular foramen (see P. Reinstrup et al., “Best zero level for external ICP transducer”, Acta Neurochirurgica (2019) 161:635).

[0027] If only a single pressure value is used in the method of this invention (for a closed system), zero-point compensation may be required to obtain an absolute ICP value associated with a specified zero reference point, thus enabling comparison with values ​​in the literature. For example, if the zero reference point is at the center of the brain and the measurement is performed with the patient supine, an offset value is needed, which depends on the vertical distance between the measurement location and the horizontal plane (venous-static axis) defined by the center of the brain. Typically, the vertical distance from the center of the brain to the root of the nose is approximately 45-48% of the vertical distance from the forehead to the back of the head. The vertical distance h from the forehead to the back of the head can be measured, and the offset value can be determined, for example, as follows:

[0028] The formula is based on 46.5% of the average distance and converts the vertical distance to mmHg. This offset can be entered into the user interface of the ultrasound system.

[0029] The typical value of h is 60 mm, therefore p offs A typical value can be 4.4 mmHg. Similar offset values ​​can be calculated in a similar manner for other zero reference points on the horizontal plane and / or head orientation during measurement.

[0030] Positioning the patient in a true supine or lateral decubitus position can be supported by a laser projector that projects horizontal and / or vertical lines onto the patient's face. This line can then be aligned with facial features such as the bridge of the nose, chin, etc. Alternatively or additionally, visual markers, transducers, or sensors can be placed on designated facial features, and the vertical distance between the measurement location and the venous stasis axis can be automatically determined based on (video) images of the patient including the markers or based on signals from the transducers or sensors.

[0031] Measurements on healthy subjects in supine and lateral positions showed an excellent correlation between pressure values ​​after correction to a given zero level.

[0032] In addition to zero-level compensation, the first value can be replaced by the second value or an estimate of central venous pressure, such as the supine peripheral venous pressure at the level of the forearm or jugular vein, as a new reference.

[0033] To obtain information about intracranial pressure, other measurements can be considered, such as venous pressure measured outside the periorbital region. Time points within the pulse or cardiac cycle can be considered when performing and / or processing measurements.

[0034] In an alternative implementation, the ICP value is obtained using machine learning methods from the pressure difference between veins, pressure values ​​associated with open and / or closed states, and / or other measurements. The machine learning methods may, for example, be based on a trained multilayer artificial neural network.

[0035] In some implementations, intracranial pressure information is obtained from the at least one first value and the duration measured from the onset of the obstruction to the point in time when the at least one first value is obtained.

[0036] In particular, this information is based on the duration required to reach a stable elevated pressure. For healthy individuals, this duration is typically about 5-6 seconds. A prolonged duration indicates a delayed pressure balance within the intracranial space, which may be a sign of elevated ICP and / or an impending rise in ICP.

[0037] In these implementations, it is not necessary to determine the absolute value of ICP. The duration can be obtained directly from multiple measurement analyses of the first value over time.

[0038] In a preferred embodiment, the geometry of a specified vein is observed based on an ultrasound image of the specified vein.

[0039] Therefore, in these embodiments, the imaging probe is an ultrasound probe. Ultrasound is particularly suitable for examining blood vessels embedded in tissues close to the skin surface. The corresponding probe is compact, cost-effective, and allows for direct examination of a specific vein.

[0040] It has been demonstrated that ultrasound frequencies in the range of 10-60 MHz, preferably 15-50 MHz, and most preferably 20-30 MHz, provide good results. These frequencies offer good resolution, and the penetration depth allows for imaging of all relevant vessels. During the measurement process, the ultrasound frequency can be adjusted to ensure sufficient penetration depth during the identification phase of the specified vein and sufficient resolution during the observation of the geometry of the specified vein.

[0041] Preferably, external pressure is applied to the designated vein through the front surface of the ultrasound probe.

[0042] In particular, the ultrasonic probe has a pressure sensor for measuring the external pressure applied by the ultrasonic probe at the measurement location. Such a probe has been proposed; see EP3716842A1 (Veinpress GmbH).

[0043] Pressure sensors can be positioned in front of the ultrasonic array, for example, comprising a fluid-filled cavity defined by a flexible membrane at its front end, and the pressure of the fluid can be measured by a sensor disposed within the cavity or connected to the cavity via a fluid line. In other embodiments, pressure sensors can be positioned (entirely) on the side of the ultrasonic array or behind it. In the latter case, for example, strain gauges can be positioned behind the array.

[0044] Alternatives to ultrasound imaging exist. The geometry of a specific vein can be observed based on A-mode ultrasound. A hybrid approach can be used, where the vein's location is identified in B-mode ultrasound images. Subsequently, the vein's geometry is monitored in A-mode using individual elements of an ultrasound array. Another alternative to ultrasound is near-infrared imaging. In principle, different methods can be used in the first stage of identifying the specific vein and in the second stage of observing its geometry. However, using the imaging process throughout ensures that the relevant vessel and its location can be tracked without any interruption, thus reducing the risk of unintentional displacement of the location or vessel.

[0045] Advantageously, the information related to venous pressure is the external pressure value corresponding to the occlusion initiation point of the specified vein.

[0046] Occlusion can be identified by a significant reduction in the diameter or cross-section of the vein and / or a lack of blood flow on Doppler ultrasound images. Alternatively or additionally, cessation of blood flow can be identified by acoustic measurements based on the noise generated by blood flow / no blood flow in the vein.

[0047] The measured occlusion pressure was closely correlated with the intravenous pressure: a strong correlation was shown between noninvasive and invasive peripheral pressures in the forearm in healthy subjects with experimentally induced venous hypertension with a wide range of pressure values ​​(r = 0.95, p = 0.001). High inter-observer consistency and an intra-group correlation coefficient of 0.988 indicate excellent reliability of the system. Optimal results were obtained when the superficial vein was compressed against the underlying bone (Ch. Thalhammer et al.: Noninvasive centralvenous pressure measurement by controlled compression sonography at the forearm, J Am Coll Cardiol. 2007 Oct 16; 50(16):1584-9).

[0048] In 2016, David Martin noted: “In this technique, a capsule filled with an ultrasound-transmitting mixture of water and glycerin and attached to a pressure gauge is attached to the head of a linear ultrasound probe. The ultrasound probe / capsule is then slowly pressed against the skin over the target vein until the vein is observed to be compressed to its closure point on the ultrasound screen. According to Laplace’s law, the pressure applied to compress the vein is considered equal to the pressure inside the vein.” (DS Martin et al.: Internal jugular pressure increases during parabolic flight, Physiol Rep. Dec 2016; 4(24): e13068).

[0049] In a preferred embodiment, multiple ultrasound image frames and assigned external pressure values ​​are stored, and the external pressure corresponding to the occlusion initiation point is determined retrospectively based on the multiple ultrasound image frames and the assigned external pressure values.

[0050] This backtracking determination can be automated, for example, through image analysis algorithms. Alternatively, it can be determined manually based on the displayed image frames of the video. The video can be played back at different speeds, and the playback speed can be adjusted by the operator.

[0051] Alternatively or additionally, the processing of imaging data can be supported by automated vein tracking and occlusion detection algorithms. This vision-based algorithm is designed to identify and track veins in ultrasound images during measurements performed by medical professionals, maintaining stability despite slight probe movement. Furthermore, the algorithm can: - Provides visual assistance to identify veins in ultrasound images, thereby improving visibility; - Guide optimal probe positioning; and / or - Provides visual confirmation of venous occlusion by observing the dilation and shape changes of the vein under obstruction.

[0052] The probe may include a mechanism for the controlled application of external pressure (i.e., compression and decompression) to simulate the process of gradually increasing external pressure until the vein collapses to obtain the mean occlusion pressure.

[0053] Units for measuring position and / or orientation can be integrated into the imaging probe, such as a 6-DOF inertial measurement unit including an accelerometer and a gyroscope. Such units provide precise data on probe positioning, tilt, and movement, guiding the user to optimal probe positioning during measurement and / or providing data for improving measurement data processing.

[0054] In addition to occlusion, external pressure values ​​can also correspond to a specific reduction in the observed diameter and / or cross-section of a vein, where the relevant quantity can be defined such that the external pressure does not correspond to complete occlusion of the corresponding vein. A series of paired external pressure values ​​and specific dimensions obtained from the corresponding images can be modeled using a fitting function, and the external pressure value corresponding to the reduction can be obtained from the fitting function.

[0055] Generally, the designated vein and location should meet the following criteria: - Veins should be close to the skin surface, which allows for reliable compression when observing changes in geometry and facilitates vein imaging; - In this position, the bone should be positioned directly behind the designated vein; this again ensures reliable compression and prevents vein displacement when external pressure is applied.

[0056] In a first preferred embodiment, the vein is designated as the nasofacial vein or its lateral branches (particularly near the confluence with the nasofacial vein), and the location is at the root of the nose.

[0057] The nasofacial vein (including its lateral branches in the nasal root region) and its location meet the above criteria. Located lateral to the lower orbital margin, this vein crosses the flat cheekbone. Its superficial location allows for visualization with high-resolution ultrasound, making it an ideal candidate for measuring venous occlusion pressure using compression ultrasound. Furthermore, the location is easily accessible, and the measurement is not particularly uncomfortable for the patient.

[0058] In a second preferred embodiment, the vein is designated as the frontal vein (also known as the supratrochlear vein), and its location is on the forehead, above the eyebrow, approximately directly above the inner canthus of the eye. Specifically, this location is within an area 3-6 cm above the inner canthus of the eye and less than 2 cm horizontally from that inner canthus. The frontal vein is easily located, and its visibility can be enhanced even when the patient performs a valsalva maneuver. In this area, the frontal vein has a superficial location, closely adjacent to the frontal bone, which is a hard, smooth base. Therefore, the vein is easily compressible, with few potential sources of error until occlusion. Furthermore, the measurement location is on the central axis of the patient's face, meaning that zero-level compensation is not required if the measurement is performed in the patient's lateral decubitus position, or is fairly straightforward if the measurement is performed in the patient's supine position.

[0059] To facilitate compression and imaging of the frontal vein, the frame of the compressor preferably has a central forehead extension that exposes and surrounds the area above the nose and the inner corner of the eye, including the aforementioned location. The horizontal width of the extension (parallel to the line connecting the centers of the two eyes) is preferably about 4-9 cm, particularly 5-7 cm. The vertical extension of the area exposed by the extension is preferably about 2-6 cm, particularly 3-5 cm. This ensures easy access to the location where the frontal vein should be compressed and monitored, while safely occluding multiple facial veins.

[0060] In other implementations, intracranial pressure information is obtained at a first time point, intracranial pressure information is obtained at a second time point, and an indicator of intracranial pressure progression is obtained by comparing the information obtained at the two time points.

[0061] An increase in pressure values ​​obtained during the measurement process over time is an indication of increased intracranial pressure. This holds true even without a defined absolute intracranial pressure value. Therefore, the method of the present invention provides meaningful results even without an absolute pressure value considered to represent a patient-related physiological quantity.

[0062] In a preferred embodiment of the system of the invention, the pressure applicator has an elongated shape, adapted to reach the pressure application points of all of the plurality of facial veins, and the pressure applicator is specifically configured to at least partially surround the periorbital region when applied to the patient's face. This leaves a gap in the eye area, improving patient comfort on the one hand, and allowing the imaging probe easy access to the designated vein on the other.

[0063] Generally speaking, pressure applicators should meet the following standards: - It can adapt to different head shapes.

[0064] - It applies the load evenly from the eye area to the scalp.

[0065] - It can quickly switch between two states (loaded, not loaded).

[0066] - It can be fixed so that its position does not move during measurement.

[0067] In a first set of preferred embodiments, the shape of the contact surface of the pressure applicator for contacting the patient's face is adaptable before the blockage begins, wherein the adapted shape can be fixedly set before pressure is applied to the patient's face.

[0068] This allows the shape of the pressure applicator to be specifically adapted to the shape of the patient's face, thereby ensuring both complete occlusion of the relevant facial veins and patient comfort. Several technical options are available: a) The pressure applicator may include an element having a cavity defined at least by a flexible, airtight material and containing a plurality of small objects (e.g., small balls made of polystyrene). In a configuration where the element contacts the patient's skin and the cavity contains air, the objects are distributed within the cavity in such a way that the external shape of the element corresponds to the shape of the facial area being contacted. If the air is removed, the position of the objects and therefore the external shape of the element are fixed.

[0069] b) The contact elements of the pressure applicator are made of an elastic material that can harden in a short time.

[0070] c) The pressure applicator has a mechanical hinge and / or guide, wherein the angular position of the extension can be fixed by a suitable means, such as screws or clamping elements.

[0071] In a simpler implementation, an elastic material, such as foam rubber, is used that can self-adjust to fit the geometry of the surface it contacts.

[0072] In other embodiments, the pressure applicator includes at least two support regions and at least one contact pressure region, wherein a spacer of variable length is disposed between each of the at least two support regions and the at least one contact pressure region in such a way that the distance between a first contact surface of the at least two support regions and a second contact surface of the at least one contact pressure region is adjustable in a direction perpendicular to the main extension direction of the pressure applicator.

[0073] This allows the pressure applicator to be switched between non-blocking and blocking configurations without affecting the positioning of the imaging probe (e.g., an ultrasound probe). Therefore, it can be ensured that the geometry of the same vessel is measured simultaneously in both configurations.

[0074] The spacer should be positioned such that it acts on a facial area in which the relevant facial veins are not blocked by the force applied by the spacer. For example, the spacer can be supported on the cheekbone and in a suitable area of ​​the forehead or brow bone.

[0075] Advantageously, the variable-length spacer includes a pneumatic element that can be actuated by an air pump.

[0076] The pneumatic element can be a pneumatic bellows, which can be filled or emptied from ambient air using an air pump and a switchable outlet valve. In the filled state, the pneumatic element lifts from the patient's face to contact the pressure area, ensuring that the patient's multiple facial veins are not blocked and that blood can flow freely through these veins. When the pneumatic element is emptied, its extension in the direction perpendicular to the main extension direction of the pressure applicator decreases, and the contact pressure area contacts the corresponding area of ​​the patient's face. The external pressure applied to the pressure applicator is thus transmitted to the face, causing blockage of the facial veins.

[0077] The air pump can be a manual pump. It is preferably equipped with a pressure gauge for measuring the pressure inside the pneumatic component cavity. Alternatively, an electric pump can be used.

[0078] In an alternative technical solution, the pressure applicator can be switched between a non-blocking and a blocking configuration by selectively pulling a retaining element connected to the applicator and allowing the applicator to retract in the direction of the patient's face. The required force can be generated, for example, by a pneumatic cylinder.

[0079] In a second preferred embodiment, the pressure applicator includes a substantially rigid frame, a holding device for attaching the frame to the patient's face, and at least one pneumatic bladder attached to the frame, the contact surface of the pressure applicator being formed by the bladder. The frame is attached to the patient's face using the holding device, and then contact pressure is established between the contact surface and the face by inflating the bladder, while the contact surface takes on the shape of the facial region to which it interacts. Therefore, the blockage can be selectively activated by a single action—inflating the bladder—while simultaneously adapting the shape of the pressure applicator to the specific shape of the patient's face.

[0080] In a preferred embodiment, the pneumatic bladder includes segments with different cross-sections. This allows for consideration of different requirements in different areas of the patient's face. Preferably, the second cross-section of the temporal segment of the pneumatic bladder is larger than the first cross-section of the forehead segment of the pneumatic bladder. In particular, the second cross-section is at least 130%, and especially at least 150%, of the first cross-section.

[0081] In a particularly preferred embodiment, the retaining device includes a segment that interacts with the posterior aspect of the patient's head and at least one additional pneumatic bladder disposed within that segment. The additional pneumatic bladder can inflate simultaneously with the pneumatic bladder attached to the frame. This minimizes frame movement when the occlusion is activated or deactivated, thereby avoiding negative impacts on probe positioning, particularly when the operator rests their hand on the frame. To achieve this, the volume and geometry of the (anterior) pneumatic bladder interacting with the patient's face should be appropriately matched to the volume and geometry of the (rear) pneumatic bladder.

[0082] This section can be made up of a strip that connects to the left and right ends of the frame. Alternatively, the section can be made up of two brackets, each connected to one end of the frame and partially encircling the patient's head on the corresponding side.

[0083] Alternatively, the pressure on the applicator is generated only from the front, and there is no need for a retaining device that interacts with the back of the patient's head. This is advantageous, or even necessary, in cases of skull injuries.

[0084] The contact surface and / or retaining device of the at least one pneumatic bladder may be coated with a peelable adhesive and / or a substance that increases friction between the contact surface and the patient's head. This reduces the risk of slippage, thereby reducing the risk of applicator displacement.

[0085] The pressure applicator, particularly the frame and / or retaining device including the corresponding bladder, can be a single-use item. This ensures reliable function, especially the function of the bladder, and improves hygiene.

[0086] In a preferred embodiment, the ultrasonic probe has a head component, the contact portion of which has a generally circular contact surface and contains ultrasonic transmission fluid.

[0087] The ultrasonic transmission fluid is a liquid with low evaporation, particularly natural oils. A circular contact surface is optimal for this application, and the head component is preferably formed such that the rear portion matches the elongated shape of the ultrasonic array, while the front portion has a circular shape. This shape is designed so that ultrasonic radiation, at least from the central portion of the ultrasonic array, is not negatively affected in its path between the front surface of the head and the ultrasonic array.

[0088] For the examination of nasal and facial veins, a contact portion with a diameter of 12-30 mm, especially 15-25 mm, has proven to be optimal. It is small enough to reach the measurement location and large enough to ensure that external pressure is evenly distributed on the head and the head-to-facial surface where the probe acts.

[0089] Preferably, the head component has a narrowing portion disposed between the front surface of the head component and the interface area for connecting the head component to the body of the ultrasound probe.

[0090] The front surface of the headpiece forms the surface that contacts the patient's skin. It is made of a flexible, ultrasound-transmitting material, particularly silicone rubber, with a thickness of 0.01-0.5 mm. The head sheath can be made of a harder material, such as the same silicone material with a greater thickness, or another material with greater stiffness than silicone.

[0091] Preferably, the front surface of the ultrasound array is embedded in a cavity defined by the head component and containing ultrasound-transmitting fluid. This reduces the number of interfaces between the array and the patient's skin, thereby improving overall image quality.

[0092] Choose the distance between the array and the front surface of the head to avoid reverberation in the visible image area.

[0093] In one variation, the method of the present invention includes the further step of irradiating a designated vein with a visible light source placed in the intracranial cavity, particularly the oropharyngeal cavity. This method is known as transillumination and is applied in various fields, such as supporting endoscopic fluoroscopy for percutaneous puncture of organs or the trachea with endoscopic assistance in gastroenterology, transillumination of paranasal sinuses, fluoroscopy of the scrotum or finger joints, or in ophthalmology.

[0094] The tissue separating the oropharynx from suitable facial veins (e.g., nasofacial veins) is quite thin and translucent. For many patients, a white LED light source with a luminous flux of approximately 500-1000 lm, placed within the oropharynx, is sufficient to illuminate the nasofacial veins and their surrounding environment, making the veins clearly identifiable from the outside, though they appear darker than the surrounding tissue. This effect is significantly enhanced when multiple facial veins are blocked, as anticipated by the method of this invention.

[0095] Irradiating veins from behind helps identify their location and provides information about the stage of facial vein occlusion.

[0096] Furthermore, video imaging devices can be used to generate high-resolution images of the irradiated specified vein. This allows for monitoring of changes caused by obstruction and / or external pressure applied to the specified vein. The imaging device can be part of an imaging probe and provide raw imaging data for further processing to obtain initial values. Alternatively, the imaging device can provide further data processed together with the data obtained by the imaging probe.

[0097] Preferably, the light source is part of the device, which has an outer housing made of materials suitable for medical use and sterilization. The emitted light should encompass a wavelength range of 600-900 nm to ensure optimal visualization of venous structures. The illumination intensity can be adjusted to suit different patient physiology and skin type. A diffuser can be incorporated to ensure uniform light distribution. As mentioned above, an LED light source is suitable because it minimizes the heat generated, thereby reducing potential discomfort to the patient.

[0098] Other advantageous embodiments and combinations of features are derived from the following detailed description and throughout the claims. Attached Figure Description

[0099] The accompanying drawings used to explain the implementation scheme are shown below: Figure 1 : A schematic diagram of blood vessels in the orbital region and cavernous sinus; Figure 2A , 2B The arrangement of veins in the orbital region and the locations where facial veins can be squeezed to prevent overflow from the orbital region; Figure 3A , 3B Front and side views of the measurement taken when the facial veins are blocked; Figure 4A , 4B : A perspective view and a top view of the pressure applicator that can be used in the system of the present invention; Figure 5 Side view of an embodiment of an ultrasonic probe that can be used in the system of the present invention; Figure 6A , 6B : Oblique view and cross-sectional view of the probe head; Figure 7A , 7B A view of the user interface of the ultrasound system during measurement according to the method of the present invention; Figure 8 The time progression of occlusion pressure measured in four series of measurements performed on two subjects; Figure 9 Increased occlusion pressure due to facial vein blockage; Figure 10 : A front view of another embodiment of the pressure applicator that can be used in the system of the present invention; Figure 11 A front view of the situation when measuring facial veins under conditions of occlusion using another implementation scheme; Figure 12A -C: Time progression of occlusion pressure measured in the other three series of measurements; Figure 13 A perspective view of another embodiment of the pressure applicator that can be used in the system of the present invention; and Figure 14 : An oblique view of an alternative embodiment for the rear bladder of the pressure applicator.

[0100] In the accompanying drawings, the same parts are given the same reference numerals. Detailed Implementation

[0101] Figure 1This is a schematic diagram of the blood vessels in the orbital region and cavernous sinus, including the connecting intracranial veins. Ophthalmic veins 12.1 and 12.2 drain blood from the orbit into the interior of the skull, flowing into the cavernous sinus (CS) 11. They include the superior ophthalmic vein 12.1, which drains into the CS 11 after passing through the superior orbital fissure. They also include the inferior ophthalmic vein 12.2, which may drain into the CS 11 independently or drain into the superior ophthalmic vein 12.1 before reaching the CS 11.

[0102] The cavernous sinus 11 (CS11) is a pair of dural venous sinuses located in the middle cranial fossa on either side of the sella turcica of the sphenoid bone. The cavernous sinus 11 itself is in direct contact with intracranial sinuses and veins. A characteristic feature of CS11 is its anatomical division into smaller chambers. In adult humans, it measures approximately 1 × 2 cm. Physiologically, due to its connection with the surrounding venous network, it has numerous inflow pathways, including the ophthalmic veins 12.1 and 12.2, the sphenoparietal sinus, the superficial middle cerebral vein (Sylvian vein), and the pterygoid plexus 13 located in the infratemporal fossa. The superior and inferior petrosal sinuses are continuations of CS, evolving into the transverse sinus and internal jugular vein as they further progress.

[0103] CS 11 is in contact with bone on one side and covered by a connective tissue membrane (approximately 50%) on the other, which is directly affected by intracranial pressure (ICP). Therefore, an increase in ICP will cause CS 11 to contract, thereby inhibiting venous return from ophthalmic veins 12.1 and 12.2 and resulting in a corresponding increase in pressure. Furthermore, CS 11 is in direct contact with intracranial sinuses and veins. There are no valves in intracranial veins. Therefore, ICP is directly transmitted to the intracranial veins and CS. Similarly, there are no valves in the orbital veins. Therefore, it is assumed that ICP is directly transmitted to the veins in the orbit.

[0104] The superior ophthalmic vein 12.1 is formed by the confluence of the medial canthal vein 14 and the supraorbital vein 15. The supraorbital vein (SOV) 15 is the largest vein in the orbit. SOV 15 provides the main venous drainage of the orbit, originating in the superior nasal quadrant of the orbit and extending posteriorly through the medial portion of the superior orbital fissure into the cavernous sinus 11. Neither the corresponding intracranial vein nor the orbital vein has valves.

[0105] In 1971, Sohan Singh Hayreh and John Edwards of the Department of Experimental Ophthalmology, University of London, published a paper on the effects of acute intracranial hypertension on ophthalmic artery and venous pressure (Brit. J. Ophthal. (1971) 55, 649). In 27 rhesus monkeys, they recorded normal systemic circulation and ophthalmic venous pressure, as well as superior sagittal sinus pressure, after intubation. In summary, they noted that "ophthalmic venous pressure and superior sagittal sinus pressure showed significant correlations with each other and with increased cerebrospinal fluid pressure." Therefore, they demonstrated a direct correlation between (artificially enhanced) ICP and ophthalmic venous pressure.

[0106] Furthermore, case studies have observed that pressure in the cavernous sinus can be transmitted to the periorbital region via emissary veins, leading to bruising in patients with elevated intracranial pressure (S. Hadjikoutis, C. Carroll, and GT Plant, “Raised intracranial pressure presenting with spontaneous periorbital bruising: two case reports,” J Neurol Neurosurg Psychiatry, Vol. 75, No. 8, pp. 1192-1193, August 2004). This supports a measurable correlation between ICP and emissary vein diameter or pressure.

[0107] The diameter of SOV 15 can be radiographically recorded using CT and MRI. However, the local resolution of ultrasound imaging is far superior to that of CT or MRI. 24 MHz ultrasound allows for a resolution of approximately 0.2 mm. Doppler ultrasound examination allows for the determination of blood flow direction and velocity.

[0108] Dilation of the supraorbital vein 15 is associated with increased intracranial pressure (ICP). Studies have shown that elevated ICP impairs the pressure gradient of venous return from the extracranial SOV 15 to the intracranial cavernous sinus 11 (Kiyotaka Kuroda et al.: Does the superior ophthalmic vein dilate in acute intracranial hypertension due to hemorrhagic stroke?, Radiology Case Reports, Vol. 18, No. 7, July 2023, p. 2522).

[0109] In another study (Jing-Feng Lirng et al.: Diameter of the Superior Ophthalmic Vein in Relation to Intracranial Pressure, AJNR Am J Neuroradiol., April 2003, 24(4):700), 69 patients (32 males, 37 females; mean age 46 ± 19 years) were included. The mean diameter of the SOV was positively correlated with ICP (r = 0.58, P < .001), and if the SOV diameter was < 1 mm, it was considered to be 0.5 mm in the calculation. Patients with elevated ICP (CSF pressure > 200 mm H2O) had a larger SOV diameter than patients with normal CSF pressure (3.0 vs 1.6 mm, P < .001). In patients with an average SOV diameter of 0.5–1 mm, the frequency of ICP elevation was 3%, 15% for those with an SOV diameter of 1.5–2 mm, and 58% for those with an SOV diameter of 2.5–5 mm (P<.001).

[0110] Based on existing evidence, there appears to be a correlation between elevated ICP and orbital vein dilation (particularly the diameter of the superior ophthalmic vein). However, not all studies have found consistent results. Some studies have concluded that the SOV does not always dilate with elevated ICP.

[0111] This invention is based on the assumption that the pressure in SOV 15 is limited to a certain maximum because the orbital veins act as emissary veins, with outflow pathways to the facial veins. Therefore, overflow is possible from the orbit, and the pressure in SOV 15 can only reach the maximum venous pressure in the facial veins. Higher pressures are alleviated through overflow from the facial veins. Therefore, despite elevated ICP, dilation of SOV 15 may not necessarily be visible on MRI or CT. Furthermore, (irregular) valves may be present in SOV 15, thus affecting pressure transmission.

[0112] This invention proposes to overcome this limitation by preventing overflow into facial veins, thereby directly acquiring the pressure in the cavernous sinus 11 through external measurement, and thus obtaining the intracranial pressure (ICP). To prevent unnecessary overflow, the relevant facial veins are compressed in areas close to the skin surface and supported by bone tissue. Compression is achieved by applying pressure to the skin using a suitable pressure applicator.

[0113] Figure 2A The arrangement of veins in the orbital region is shown. In addition to the superior ophthalmic vein 12.1, inferior ophthalmic vein 12.2, medial canthal vein 14, and supraorbital vein 15 mentioned above, these veins also include, for example, the superior palpebral vein 16.1 and inferior palpebral vein 16.2 that drain the upper eyelid.

[0114] exist Figure 2B In the diagram, arrows indicate locations 21.1...5 where the relevant facial veins can be compressed to prevent overflow from the orbital region. The goal is to temporarily block all larger vessels that could potentially overflow from the system formed by the facial veins downstream to the corresponding blockage and the ophthalmic veins 12.1, 12.2 directly connected to the cavernous sinus 11. It is not important if smaller veins with significantly smaller cross-sectional areas are not blocked, as they do not significantly contribute to overflow from the system.

[0115] Figure 3A , 3B The images show a front and side view of the measurement taken while the facial veins are occluded. The relevant facial veins were occluded using a pressure device 30, which will be described in more detail below. Figure 3A In the diagram, only dashed lines represent the contact surface of the pressure applicator 30 in its activated configuration. Arrows indicate position 22 at the root of the nose, above the nostrils, where the nasofacial vein 17 (or its lateral branches) is compressed and its occlusion is monitored by ultrasound. The same position 22 is also shown... Figure 3B In the middle. The nasofacial vein 17 is located superficially on the bone at the root of the nose, close to the skin. It can be easily compressed.

[0116] The pressure applicator compresses the periorbital region in a selected area, thereby compressing the veins in the skin. If the pressure is high enough, blood flow from the orbit to the facial veins stops. This results in an outwardly closed funnel-shaped measurement system. Therefore, venous blood flow in the orbit is diverted to the cavernous sinus 11, forming a connected vascular system. The venous pressure in the orbit rises to the outflow pressure in the cavernous sinus 11.

[0117] Figure 4A This is a perspective view of an embodiment of a pressure applicator that can be used in the system of the present invention. Figure 4B A top view of the pressure generator is shown.

[0118] The pressure applicator 30 has a face mask 31 and a strap 34. The face mask 31 includes a C-shaped frame 32, wherein the open legs of the frame 32 are connected by a nose bridge 33. The frame 32 and the nose bridge are made of a rigid plastic material. In the frame 32, vertical grooves 32a are formed on both the upper legs and the open legs, symmetrical about a central axis of symmetry, with the upper groove on one side aligned with the lower groove on the same side. The grooves 32a increase the flexibility of the face mask 31 regarding its bending about its axis of symmetry. The geometry of the frame 32 and the nose bridge 33 is adapted to the geometry of the human face, so that the face mask 31 can be applied to the face in such a way that the frame 32 surrounds the two eye socket areas, while the nose bridge 33 surrounds the wearer's nose. In its two outer regions, the frame 32 has a set of three fixing holes 32a. At the upper center position, an attachment hook 32b is arranged.

[0119] The strap 34 is made of a non-elastic textile material. At both ends, it has adjustment mechanisms 34a and hooks 34b. Using the hooks 34b and fixing holes 32a, the strap is detachably attached to the frame 32 of the mask 31. This allows the mask 31 to be secured to the wearer's head. Selecting different fixing holes 32a allows for different load distributions of the strap 34 on the upper and lower edges of the mask 31. Another strap (not shown) can be attached to the attachment hooks 32b of the mask 32 and the rear of the strap 34 to further secure the mask 31 to the head and prevent the strap 34 from slipping downwards. In alternative embodiments (see below)... Figure 13 (Description) The strap includes mating Velcro elements and passes through lugs arranged on both sides of the frame. This replaces the hooks and fixing holes shown in the figure, as well as the length adjustment mechanism. Other variations of the adjustment mechanism are possible, such as using a system employing a knob (like the BOA Fit System supplied by Boa Technology, Inc.), or a pull cord stop. The adjustment mechanism can be located on the side or rear of the strap, or on the face mask.

[0120] The pressure applicator 30 also includes a pneumatic system. This system has a C-shaped bladder 35 attached to the rear surface of the C-shaped frame 32 of the mask 31. It also has a rear bladder 36 supported by the inner surface of a load cover 37, which itself is attached to the inside of the strap 34. Both the C-shaped bladder 35 and the rear bladder 36 are connected to a common pressure source 38 via corresponding conduits. The pressure source 38 has a hand pump 38a, an exhaust port 38b, and a pressure gauge 38c. To enhance the scalability of the bladders 35 and 36, some or all may have several stacked chambers and / or bellows. Pressure applicators of different sizes and / or curvatures can be provided to match different facial shapes.

[0121] Figure 5 This is a side view of an embodiment of an ultrasonic probe that can be used in the system of the present invention. Figure 6A An oblique view of the probe head is shown, and Figure 6B A cross-sectional view of the head is shown.

[0122] The ultrasound probe 40 has a housing 41 that houses electronics 42 for controlling the device and processing measurement results. A linear ultrasound array 43 with 32 elements is housed at the front of the housing 41. Tissue imaging of the region of interest is performed using a frequency of 24 MHz. The ultrasound probe 40 provides B-mode images with 256 gray levels and a resolution of 0.07–0.10 mm.

[0123] Alternatively, an ultrasound array with more elements (e.g., 128 elements) can be used. Once the area to be observed is identified, the control software can dynamically reduce the number of active elements. Simultaneously, the ultrasound frequency can be varied, employing values ​​higher or lower than 24 MHz.

[0124] The head 44 of the ultrasonic probe 40 is comprised of an attachment member 45, which is made from a single piece of Shore A 40 A silicone material. The attachment member 45 has a base 45a with an elliptical contact surface (28 mm / 14 mm axis), which can be attached to a corresponding mating portion of the housing 41 of the ultrasonic probe 40. Connected to the elliptical base is a circular front portion 45b (20 mm in diameter) made of the same material but with a smaller wall thickness. The maximum wall thickness in the base 45a is approximately 1.5 mm. The wall thickness is minimal (approximately 0.3 mm) at the substantially flat front surface 45c of the front portion 45b.

[0125] A closed cavity is formed between the attachment member 45 and the wall structure within the housing 41. The cavity is filled with an ultrasonically transmitting liquid, such as low-viscosity natural oil. The liquid surrounds the ultrasonic array 43. A pressure sensor 46 communicates with the cavity via a thin tube and allows measurement of the internal pressure within the cavity. This sensor allows for a measurement rate of at least 20 Hz and a resolution of 0.1 mbar. The corresponding technical solution is described in WO2023 / 104390 A1 (Compremium AG).

[0126] Measurements can be performed using the pressure applicator 30 and the ultrasonic probe 40 according to the method of the present invention. Figure 7A , 7B This is a view of the user interface of the ultrasound system during such measurements.

[0127] An exemplary sequence of steps in the measurement method may be as follows, in which a medical professional performs these steps under the guidance of the ultrasound system's user interface: 1. The patient lies supine on a 4° inclined surface, with the head lower than the feet. This ensures complete venous filling. Other measures can be taken to ensure complete venous filling, such as further elevating the patient's legs, having the patient sit with their head tilted forward, or having the patient lie on their side.

[0128] 2. Medical professionals measure the distance from the measurement point around the eye socket to the external auditory canal (meatus acusticus). This will later be used for hydrostatic pressure correction. This value is entered through the system's user interface.

[0129] 3. Select the compressor 30 from several available sizes based on the geometry of the patient's head. In particular, select the compressor based on the width of the forehead. Secure the compressor 30 to the patient's head. To do this, shorten the strap using the adjustment mechanism 34a until it fits snugly against the head, but without applying force to the mask 31. The bladders 35 and 36 are not inflated, and the vent 38b is open. At this point, the mask 31 is positioned such that its frame 32 is in the final position that will be used in subsequent steps to occlude facial veins.

[0130] 4. Next, the initial measurement of the occlusion pressure of the nasofacial vein is performed. First, the integrated pressure sensor is calibrated, and the measured pressure value is zeroed. Additionally, the user can specify parameters for the probe's linear ultrasound array, such as depth, gain, focus, and frequency.

[0131] Next, the operator grasps the ultrasound probe 40 and orients it head-down. In this orientation, the probe's pressure sensor is calibrated to 0 mmHg.

[0132] Next, the head of the gel-coated ultrasound probe 40 is positioned so that its center contacts the skin covering the nasofacial vein itself or its lateral branches (near the confluence with the nasofacial vein), and the corresponding vein is clearly visible in the ultrasound image. (Optionally, this step is supported by illuminating the vein and surrounding tissue from behind using a light source placed in the oropharynx, as described above.) The probe should be oriented so that its array is perpendicular to the direction of the root of the nose on the corresponding half of the patient's face. In most cases, the facial vein should be located approximately 2 cm below the lower eyelid. During the examination, the operator's guiding hand rests on the patient's head at least at one point, and the probe is rotated and aligned until the cross-section of the target vessel appears as a circular outline. Vessels may be compressed under low external pressures of 5 mmHg or less. Therefore, to find a suitable vessel, the outline that collapses under load should be sought in the sample by a pumping motion. The lower load should be well below 5 mmHg.

[0133] Figure 7A An ultrasound image is shown in which the uncompressed blood vessel is clearly visible (Item 1). It is approximately 2.8 mm wide and 1.6 mm high. The outline is clear. Now, external pressure is increased between the ultrasound probe head and the skin until the vessel collapses. Figure 7B The image shown is of the impending collapse (Item 2). The corresponding value of the required external pressure is recorded (Item 3). Preferably, this process is repeated several times, and the average pressure value is taken as the first value of the occlusion pressure of the nasofacial vein.

[0134] 5. Now, by closing the vent 38b and using the hand pump 38a, inflate the bladders 35 and 36 until the internal pressure reaches at least 60-100 mm Hg, particularly 60 mm Hg. The pressure can be monitored using a pressure gauge 38c. Inflating the bladders causes pressure to be established between the C-shaped bladder 35 and the patient's face, without substantial movement of the frame 32 of the mask 31. This is because the force required to support the patient's head and block facial veins is primarily provided by the rear bladder 36, while the main purpose of the front bladder 35 is to conform the internal shape of the mask 31 to the patient's face. The groove 32a enhances the flexibility of the mask, thus supporting this.

[0135] As described above, blocking facial veins prevents leakage from the orbit into these veins. This creates a closed venous measurement system consisting of interconnected vessels leading only to the cavernous sinus. The venous pressure in the orbit rises to the pressure in the CS (cerebrospinal sinus).

[0136] Due to obstruction of facial veins, the vessels should appear dilated on ultrasound images. Furthermore, ultrasound imaging reveals that obstruction causes a change in the shape of the nasofacial veins, with their width-to-height ratio decreasing by approximately 15%. These are important indicators that ensure the vessels around the eyes are fully compressed under load. If changes in load are not accompanied by changes in venous blood stasis, meaningful ICP-related information may not be obtained in many cases.

[0137] During inflation, which blocks the facial veins, the ultrasound probe 40 remains in place and the blood vessels are observed without interruption. This ensures that the same vein at the same location will be measured in subsequent measurements.

[0138] 6. After achieving the required pressure within the sac and delaying for at least 10 seconds to ensure pressure balance within the now-closed facial veins and cavernous sinus system, a second measurement of the occlusion pressure of the nasofacial veins is performed at the same location as the first measurement. The protocol is the same as the first measurement. This yields a second value for the occlusion pressure of the nasofacial veins.

[0139] Steps 4-6 described can be repeated several times to further reduce statistical error and / or monitor the progression of occlusion pressure or output over time. Based on repeated measurements covering minutes to hours, a progression curve can be established. Based on this curve, particularly the study of its slope, an opinion can be drawn about the patient's health condition.

[0140] Measurements can be taken on both the right and left sides of the patient's face. Significant differences in pressure measurements can be valuable indicators of conditions that affect blood flow on one side while leaving the other unaffected, such as eye tumors, certain eye injuries, and thrombosis. Furthermore, taking measurements on both sides ensures the identification of potential systematic errors, and that affected values ​​are not used as the basis for decisions made by responsible personnel.

[0141] The method of this invention has been experimentally tested. Measurements on healthy volunteers confirmed an increase in venous pressure upon occlusion of facial veins. Within a maximum of 15 seconds after occlusion of the facial veins, the venous pressure rose rhythmically. It is this increase in orbital venous pressure that constitutes the pressure difference between veins. Δp :

[0142] in p nonobs This represents the occlusion pressure under unobstructed conditions, while p obs This indicates the occlusion pressure in cases of facial vein obstruction. In all measurements of the test subjects, after the initial 15-second phase, regardless of head position (supine -15° and lateral decubitus), and over time (up to 15 minutes), [the following was observed]. Δp Stability of values.

[0143] Using a preliminary implementation of the pressure applicator obtained from swimming goggles, 208 individual measurements were performed on two subjects. The subject's supporting surface tilt angle was -3.6°. The effect of this implementation on facial veins was comparable to that of the aforementioned pressure applicator.

[0144] Figure 8 The time progression of occlusion pressure measured in four series of measurements performed on two subjects is shown. The horizontal axis represents time, and the vertical axis represents the measured pressure, including the unoccluded and occluded phases of the facial veins. The four curves represent the following:

[0145] The deviation at the end of curve 53 indicates that tracking blood vessels and measurement locations is crucial throughout the measurement series.

[0146] Typically, after the bladder is inflated to the occlusion pressure, a new pressure equilibrium is reached within 5-6 seconds at a higher pressure level.

[0147] Further measurements were taken, and an average increase of 8.4 mmHg in occlusion pressure was observed. These measurements were performed by three researchers using the above protocol on the right eye of two subjects. Figure 9The results are summarized. In the first part, the bars represent the occlusion pressure values ​​of the nasofacial veins when the facial veins are not occluded, obtained from four different measurement series. In the second part, the bars represent the corresponding occlusion pressures of the nasofacial veins when the facial veins are occluded. The other two parts show the results from the average value (third part) and from individual values. Δp' (Part Four) Obtaining the pressure difference between veins Δp The values ​​are obviously the same, however, the dispersion of results obtained from a single value is slightly smaller (3.5 mmHg vs. 3.7 mmHg). As mentioned above, Δp The value of is a good starting point for obtaining ICP information, and at least its development over time is considered to provide physiologically relevant information about a patient's ICP status.

[0148] Several potential sources of systematic error were examined. First, the effect of the pressure applied to the skin by the pressure applicator was examined in the experiments. In the first experiment, superficial skin displacement (stretching) caused by changes in the pressure applicator load was measured. The load of the pressure applicator pulled the skin downwards by approximately 0.5 mm. Next, two series of occlusion pressure measurements of the nasofacial veins were performed. In the first series, the skin was unaffected by external factors except in the area contacted by the ultrasound probe. In the second series, the skin was stretched downwards by more than 0.5 mm by applying tape. However, no significant effect was observed when comparing the results of the two series. Therefore, it can be assumed that the skin tension caused by the pressure applicator has no effect on the measurement results.

[0149] Comparative measurements performed on patients in supine and lateral decubitus positions showed that the difference in occlusion pressure corresponded to the difference in the vertical position of the measurement point between the two positions. Δp The values ​​did not show significant differences.

[0150] Furthermore, MRI scans of both subjects, each lasting 30 minutes, showed no effect on intracranial veins under activator application and pressure. This suggests that the measurement's influence on ICP values ​​is likely very small.

[0151] The influence of outflow through the pterygoid plexus on the pressure measured under obstruction was also examined, as there may be venous connections to the extracranial pterygoid sinus, and overflow may occur in these vessels. These vessels have a much smaller cross-sectional area than the obstructed facial veins; therefore, overflow to the pterygoid plexus could be expected only after a period of time. However, measurements showed no pressure drop for at least 15 minutes after the application of the pressure applicator. This is a clear indication that the potential bypass has no significant effect. It is assumed that the cross-sectional area of ​​the pterygoid sinus vessels is very small, and associated overflow will not occur. It should be noted that, in principle, in the context of this invention, the pterygoid plexus could be obstructed if necessary, for example, using a cheek pad that applies pressure to the patient's cheek. However, the above results suggest that such a pad is unlikely to be needed.

[0152] Figure 10 This is a front view of another embodiment of the pressure applicator that can be used in the system of the present invention. In particular, this other embodiment is adapted for measurement on the frontal vein, located on the forehead, above the eyebrow, and approximately directly above the inner corner of the eye (see [link to original text]). Figure 11 (This shows a front view of the situation when measuring in a state of facial vein occlusion using this alternative embodiment).

[0153] The pressure applicator 130 has a mask 131 and a strap 134. The mask 131 is similar to a combination Figure 4A , 4B The mask 131 is described. The main difference lies in the central forehead extension, which, when attached to the patient's face, exposes the forehead area above the nose and inner corners of the eyes. Therefore, the mask 131 has a C-shaped frame 132, with open legs of the frame 132 connected by a bridge of the nose 133. At the upper part, opposite to the bridge of the nose 133, the frame 132 forms a convex extension 139, extending substantially within the main plane of the frame 132, increasing the area enclosed by the frame 132. The extension is approximately semi-circular in shape. The width of the surface enclosed by the extension 139 (parallel to the plane defined by the strap 134) is approximately half the width of the surface enclosed by the frame, while the height of the enclosed surface (perpendicular to the width) is approximately two-thirds of the height of the total surface enclosed by the frame 132.

[0154] The frame 132 and nose bridge 133 are made of rigid plastic material. The geometry of the frame 132 and nose bridge 133 is adapted to the geometry of the human face, so that the mask 131 can be applied to the face in such a way that the frame 132 surrounds the two eye socket areas and the lower center of the forehead, while the nose bridge 133 surrounds the wearer's nose. The frame 132 has a set of three fixing holes 132a in its two outer regions. An attachment hook 132b is arranged at the upper center.

[0155] The tape 134 and its function are the same as those in the first embodiment described above.

[0156] The pressure applicator 130 also includes a pneumatic system. This system has a front bladder 135 that matches the extension and geometry of the frame 132. The front bladder 135 is attached to the rear surface of the frame 132 of the mask 131. It also has a rear bladder 136, which is supported by the inner surface of a load shroud 137, which itself is attached to the inside of the strap 134. Similarly, both the front bladder 135 and the rear bladder 136 are connected to a common pressure source with a hand pump and a pressure gauge. Pressure applicators of different sizes and / or curvatures can be provided to match different facial shapes.

[0157] Use pressure applicator 130 to occlude the relevant facial veins. Figure 11 In the diagram, the contact surface of the pressure applicator 130 in its activated configuration is indicated by a dashed line. An arrow indicates location 122 at the root of the nose, above the nostrils, where the frontal vein 118 is compressed and its occlusion is monitored by ultrasound. The frontal vein 118 is located superficially beneath the skin on the frontal bone. It can be easily compressed. Except for using a different pressure applicator and taking measurements on another designated vein, the steps of the measurement process correspond to those described above in conjunction with the first embodiment using the pressure applicator.

[0158] It should be noted that the measurements required in the method of this invention can only be performed on intact skin. Furthermore, orbital diseases that affect venous blood flow, such as Graves' disease, tumors, and cavernous sinus syndrome (cavernous sinus thrombosis), are contraindications.

[0159] Figure 12A -C shows another implementation using a pressure applicator, based on the time progression of occlusion pressure measured in three further series of measurements performed on the frontal vein.

[0160] The horizontal axis represents time, and the vertical axis represents the measured pressure. The graph illustrates the following: Figure 12A The pressure applicator was attached to the patient's face but not inflated. Therefore, the pressure applied by the applicator was negligible. Five consecutive cycles of increasing and decreasing the external pressure applied by the probe were performed. In each cycle, the pressure was increased to exceed the occlusion pressure. Thus, five occlusion pressure values ​​were obtained, measured approximately 3 s, 9 s, 14 s, 18 s, and 23 s after the start of the examination. The mean occlusion pressure obtained was 9.0 mmHg, with a standard deviation of 0.6 mmHg.

[0161] Figure 12B The pressure applicator was inflated and applied approximately 60 mmHg of pressure along its contact surface with the patient's face. Six consecutive cycles of increasing and decreasing the external pressure applied by the probe were performed. In each cycle, the pressure was increased to exceed the occlusion pressure. Thus, six occlusion pressure values ​​were obtained, measured approximately 3 s, 8 s, 13 s, 18 s, 23 s, and 26 s after the start of the examination. The mean occlusion pressure obtained was 14.2 mmHg, with a standard deviation of 2.0 mmHg.

[0162] Figure 12CThe pressure applicator remained inflated, applying approximately 60 mmHg of pressure along its contact surface with the patient's face. In the first phase, four consecutive cycles of increasing and decreasing the external pressure applied by the probe were performed. In each cycle, the pressure was increased to exceed the occlusion pressure. Therefore, four occlusion pressure values ​​were obtained, measured approximately 4 s, 7 s, 10 s, and 14 s after the start of the examination. The mean occlusion pressure obtained in this first phase was 12.5 mmHg, with a standard deviation of 1.5 mmHg. In the second phase, six additional consecutive cycles of increasing and decreasing the external pressure applied by the probe were performed. In each cycle, the pressure was increased to exceed the occlusion pressure. Throughout the second phase, the patient performed the Valsalva maneuver. Six occlusion pressure values ​​were obtained, measured approximately 22 s, 26 s, 30 s, 34 s, 38 s, and 42 s after the start of the examination. The mean occlusion pressure obtained in this second phase was 28.3 mmHg, with a standard deviation of 3.0 mmHg.

[0163] The results of these further measurements confirmed the findings summarized above. In particular, the valsalva maneuver is an established method for simulating increased intracranial pressure; see, for example, FP Tiecks, AM Lam, BF Matta, S. Strebel, C. Douville, and DW Newell, “Effects of the valsalva maneuver oncerebral circulation in healthy adults. A transcranial Doppler Study,” Stroke 26(8), 1386–1392 (1995). Figure 12C In the third measurement series shown, the effect of increased ICP is clearly visible, confirming that when the facial veins that are capable of achieving pressure balance are blocked, increased ICP itself manifests as an increase in the pressure of the frontal vein occlusion.

[0164] Figure 13 This is a perspective view of yet another embodiment of the pressure applicator that can be used in the system of the present invention. (and in conjunction with...) Figure 10 , 11 The described implementation is similar, and this other implementation is suitable for measurement on the frontal vein, located on the forehead, above the eyebrow and approximately directly above the inner corner of the eye.

[0165] The pressure applicator 230 has a mask 231 and a strap 234. The mask 231 is similar to a combination Figure 10The described mask 131. The main differences involve the shape of the mask 231 in the forehead region and the fastening mechanism of the strap 234. The mask 231 includes a C-shaped frame 232, wherein the opening legs of the frame 232 are connected by a bridge of the nose 233. (The last sentence appears to be incomplete and possibly refers to a combination of two parts.) Figure 10 Compared to the described pressure applicator, the mask's extension in the forehead region is not a central forehead extension that exposes the central area of ​​the forehead above the nose, but rather is generally larger, exposing not only the central portion of the forehead but also a larger forehead region extending further to the left and right. This increases the available space for measuring facial veins within the obstructed area.

[0166] The frame 232 and nose bridge 233 are made of rigid plastic material. The geometry of the frame 232 and nose bridge 233 is adapted to the geometry of the human face, allowing the mask 231 to be applied to the face in such a way that the frame 232 surrounds the two eye socket areas and the lower forehead, while the nose bridge 233 surrounds the wearer's nose. The frame 232 has buckles 232a and 232b in its two outer regions. Both ends of the strap 234 pass through their respective buckles 232a and 232b and are connected to the corresponding adjacent portions of the strap 234 by Velcro fasteners. This allows for easy adjustment of the length of the strap 234 as well as tightening and loosening of the strap 234.

[0167] The pressure applicator 230 also includes a pneumatic system. This system has a front bladder 235 that matches the extension and geometry of the frame 232. The front bladder 235 is attached to the rear surface of the frame 232 of the mask 231. It also has a rear bladder 236, which is itself attached to the inside of the rear section of the strap 234, wherein the width of the strap 234 is increased. Both the front bladder 235 and the rear bladder 236 are made of fiber-reinforced plastic foil. Similarly, both the front bladder 235 and the rear bladder 236 are connected to a common pressure source with a hand pump and a pressure gauge. Pressure applicators of different sizes and / or curvatures can be provided to match different facial shapes.

[0168] The steps for blocking the relevant facial veins and performing the measurements are combined with the above. Figure 11 The descriptions are the same.

[0169] Figure 14 This is a perspective view of an alternative embodiment of the rear sac for the compressor. The rear sac 336 has a ring-shaped design (“donut”) and is directly attached to the strap 334, eliminating the need for a load-bearing cover. This improves patient comfort. Due to its shape, the rear sac 336 stabilizes the compressor's position over the patient's head. Furthermore, if the patient is in a supine position, the shape of the rear sac 336 further stabilizes the head position on the support surface.

[0170] This invention is not limited to the disclosed embodiments. First, the features of the hardware components can differ. For example, an automatic pump can be used instead of a hand pump to inflate the bladder of the inflator, and the details of the inflator and the ultrasonic probe can differ from the described embodiment.

[0171] Further measures can be taken to further improve measurement quality, such as using Doppler ultrasound data or image processing, such as edge detection. Obstruction force can be measured directly, and / or facial vein obstruction can be monitored, for example, through further (Doppler) ultrasound measurements.

[0172] As an alternative or supplement to determining vein-to-vein pressure and / or ICP values, the progression of pressure values ​​measured on a closed system and / or vein-to-vein pressure values ​​can be monitored, and conclusions can be drawn from such monitoring.

[0173] In summary, it is noteworthy that the present invention provides a method and system for obtaining information on intracranial pressure in a patient, which is non-invasive, reliable, and has minimal impact on the patient.

Claims

1. A non-invasive method for obtaining information about a patient's intracranial pressure, comprising the following steps: a) During a first time interval, the multiple facial veins leading out of the periorbital region are blocked by applying external pressure to each of the multiple facial veins of the patient. b) During the first time interval, in the region, at a location upstream of the blockage of the plurality of facial veins, external pressure is applied to a designated vein connected to an intracranial vessel; c) Observe the changes in the geometry of the designated vein caused by the external pressure to obtain at least one first value related to the venous pressure in the designated vein; d) Process the at least one first value to obtain information about the intracranial pressure.

2. The method according to claim 1, characterized by the following steps: - During a second time interval, before and / or after the first time interval, an external pressure is applied to the designated vein at the location, and the change in the geometry of the designated vein caused by the external pressure is observed to obtain at least one second value related to the venous pressure; - Use the at least one first value and the at least one second value to obtain information about the intracranial pressure.

3. The method according to claim 2, characterized in that, The intracranial pressure value is obtained by the difference between the at least one first value and the at least one second value.

4. The method according to claim 1, characterized in that, The intracranial pressure information is obtained from the at least one first value and the duration measured from the start of the obstruction to the point in time when the at least one first value is obtained.

5. The method according to any one of claims 1 to 4, characterized in that, The geometry of the specified vein is observed based on the ultrasound image of the specified vein.

6. The method according to claim 5, characterized in that, The external pressure is applied to the designated vein through the front surface of the ultrasound probe.

7. The method according to any one of claims 1 to 6, characterized in that, The change in geometry caused by the external pressure is observed to determine the occlusion initiation point of the designated vein, and the venous pressure information is the external pressure value corresponding to the occlusion initiation point of the designated vein.

8. The method according to claim 7 and claim 5 or 6, characterized in that, Multiple ultrasound image frames and assigned external pressure values ​​are stored, and the external pressure corresponding to the occlusion initiation point is determined retrospectively based on the multiple ultrasound image frames and the assigned external pressure values.

9. The method according to any one of claims 1 to 8, characterized in that, The designated vein is the nasofacial vein or its lateral branches, and the location is at the root of the nose.

10. The method according to any one of claims 1 to 8, characterized in that, The designated vein is the frontal vein, and the location is on the forehead.

11. The method according to any one of claims 1 to 10, characterized in that, The intracranial pressure information is obtained at a first time point, the intracranial pressure information is obtained at a second time point, and an indicator of intracranial pressure progression is obtained by comparing the information obtained at the two time points.

12. The method according to any one of claims 1 to 11, further comprising the following step: The designated vein is illuminated using a visible light source placed in the intracranial cavity, particularly the oropharyngeal cavity.

13. A system for non-invasively obtaining information about intracranial pressure in a patient, comprising: a) A pressure applicator for blocking the multiple facial veins extending from the periorbital region by applying external pressure to each of the multiple facial veins of the patient; b) An imaging probe, used within the region, upstream of the site of occlusion of the plurality of facial veins, to observe changes in the geometry of a designated vein caused by external pressure applied to a designated vein connected to an intracranial vessel; and c) A processor for processing at least one first value related to venous pressure in the designated vein, the at least one first value being obtained from observed changes in geometry to obtain information about the intracranial pressure.

14. The system according to claim 13, characterized in that, The pressure applicator has an elongated shape adapted to reach the pressure application points of all of the plurality of facial veins, and the pressure applicator is specifically configured to at least partially surround the periorbital region when applied to the patient's face.

15. The system according to claim 14, characterized in that, The shape of the contact surface of the pressure applicator for contacting the patient's face is adaptable before the blockage begins, wherein the adapted shape can be fixed before pressure is applied to the patient's face.

16. The system according to any one of claims 13 to 15, characterized in that, The pressure applicator includes at least two support regions and at least one contact pressure region, wherein a spacer of variable length is disposed between each of the at least two support regions and the at least one contact pressure region in such a way that the distance between the first contact surface of the at least two support regions and the second contact surface of the at least one contact pressure region is adjustable in a direction perpendicular to the main extension direction of the pressure applicator.

17. The system according to any one of claims 13 to 15, characterized in that, The pressure applicator includes a substantially rigid frame, a holding device for attaching the frame to a patient’s face, and at least one pneumatic bladder attached to the frame, the contact surface of the pressure applicator being formed by the bladder.

18. The system according to claim 17, characterized in that, The frame has a central forehead extension that, when attached to a patient's face, exposes and surrounds the area above the nose and the inner corner of the eye.

19. The system according to any one of claims 13 to 18, characterized in that, The imaging probe is an ultrasonic probe.

20. The system according to claim 19, characterized in that, The ultrasonic probe has a head component, the contact portion of which has a generally circular contact surface and contains ultrasonic transmission fluid.

21. The system according to claim 20, characterized in that, The head component has a narrowing portion disposed between the front surface of the head component and an interface area for connecting the head component to the body of the ultrasound probe.

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