GB2562119A

GB2562119A - Improvements in or relating to organic material

Info

Publication number: GB2562119A
Application number: GB1707266.1A
Authority: GB
Inventors: James Marchbanks Robert; Bulters Diederik; Birch Tony
Original assignee: Marchbanks Measurement Systems Ltd
Current assignee: Marchbanks Measurement Systems Ltd
Priority date: 2017-05-05
Filing date: 2017-05-05
Publication date: 2018-11-07
Anticipated expiration: 2037-05-05
Also published as: GB2562119B; WO2018202680A1; GB201707266D0

Abstract

A device 1 is disclosed having a spectacle-shaped frame 2 for supporting one or more pods 60A, 60B, each pod comprising apparatus for non-invasive measuring of intracranial pressure (ICP) using a tympanic measurement technique and ear probe tube 21A, 21B. The glasses frame may comprise bridge 5, nose rest 6, arms 3A, 3B and the pods may be releasable via knob 66A, 66B, the ear tubes detachable by resilient releasable clip and rotatable via ball joint 70A, 70B. Also disclosed is a method of diagnosing a medical condition by measuring a response to externally induced intracranial pressure change using a tympanic technique. The pressure change may be applied by a rotatable bed and actuator (figure 5, 90 & 92) which may tilt the bed by raising its upper end. Providing the device in the form of a spectacles may be more suited for use with a patient in neuro-intensive care.

Description

(71) Applicant(s):

Marchbanks Measurement Systems Limited (Incorporated in the United Kingdom)

Bryns Dell House, St Marks Road, Lymington, Hampshire, SO41 8HA, United Kingdom (72) Inventor(s):

Robert James Marchbanks Diederik Bulters Tony Birch (56) Documents Cited:

GB 2210168 A EP 2992822 A1 WO 2010/151734 A2 US 4413634 A (58) Field of Search:

INT CLA61B Other: WPI, EPODOC

GB 2075679 A WO 2017/035406 A2 WO 2008/101220 A2 US 20040087871 A1 (74) Agent and/or Address for Service:

J.P. Peel & Co Ltd

Gainsborough House, 2 Sheen Road, RICHMOND, Surrey, TW9 1AE, United Kingdom (54) Title of the Invention: Improvements in or relating to organic material Abstract Title: Measuring intracranial pressure using tympanic technique (57) A device 1 is disclosed having a spectacle-shaped frame 2 for supporting one or more pods 60A, 60B, each pod comprising apparatus for non-invasive measuring of intracranial pressure (ICR) using a tympanic measurement technique and ear probe tube 21 A, 21B. The glasses frame may comprise bridge 5, nose rest 6, arms 3A, 3B and the pods may be releasable via knob 66A, 66B, the ear tubes detachable by resilient releasable clip and rotatable via ball joint 70A, 70B. Also disclosed is a method of diagnosing a medical condition by measuring a response to externally induced intracranial pressure change using a tympanic technique. The pressure change may be applied by a rotatable bed and actuator (figure 5, 90 & 92) which may tilt the bed by raising its upper end. Providing the device in the form of a spectacles may be more suited for use with a patient in neuro-intensive care.

At least one drawing originally filed was informal and the print reproduced here is taken from a later filed formal copy.

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IMPROVEMENTS IN OR RELATING TO ORGANIC MATERIAL [001] The present invention relates to a device and kit for measuring intracranial fluid pressure (ICP) and a method of diagnosing a medical condition by measuring a response to an externally induced intracranial pressure change.

[002] Non-invasive measurement of ICP is a goal that a number of researchers have strived for since the 1980s. Many of the patented techniques use ultrasound to measure physiological properties such as the internal diameter of the cranium; intracranial or intraocular blood flow, or the acoustic properties of the cranium or pulsations of the cerebral ventricles. The main problems with these techniques are: a. Choosing a physiological characteristic that is directly and invariably related to ICP or cerebral perfusion pressure (CCP). A commonly used characteristic relates to the amplitude of the cardiovascular pulse. This is known to increase in amplitude with increasing intracranial pressure; however, the major shortcomings are the many other factors that also change pulse amplitude, for example increasing cerebral blood flow with exercise. Critically, an increase in the cerebral outflow resistance of blood or CSF will dramatically change the pulse amplitude. It is, therefore, very difficult, if not impossible to differentiate between an increase in ICP and these other conditions.

b. Maintaining a good repeatability between one test session and the next is often very difficult or impossible for many of the patented techniques. Good repeatability and long-term stability is essential for day-to-day or long-term assessment of ICP in an individual patient. Changes in ICP with treatment or chronic changes over perhaps periods of several years are the clinical requisite for managing the brain-injured patient. With most of the patented techniques, it is impossible to reposition the ultrasound sensor so that accurate serial measurements can be made - the techniques are designed for continuous measurements where the sensor remains insitu for the duration of the measurement.

c. Being able to calibrate the patented non-invasive technique against actual changes in ICP on an individual patient basis. Inventors of each technique have attempted to this with varying degrees of success, however, most if not all fail if the sensor is removed.

[003] GB2075679 and GB2210168 disclose a tympanic measurement technique using an apparatus carried by a helmet or harness. In GB2075679, the apparatus comprises an ear probe for attachment to one ear of a patient and a loudspeaker for mounting on the other ear. The helmet on which the apparatus is mounted includes a boom and a counterweight. In GB2210168, the ear probe includes a loudspeaker within the probe.

[004] A way of ameliorating these problems has been sought.

[005] According to the invention there is provided a device having a spectacle-shaped frame for supporting one or more pods wherein each pod comprises an apparatus for measuring intracranial pressure using a tympanic measurement technique and an ear probe tube for connecting the pod to a patient's ear.

[006] The advantages of providing the device in the form of a spectacle-shaped frame instead of a helmet or harness include that the device may more readily be used with a patient in neuro-intensive care where helmets, headsets and/or headbands are difficult or impossible to fit because of life support and monitoring apparatus.

[007] In some embodiments, the frame may comprise a bridge shaped for fitting across a patient's forehead, a nose rest and a pair of arms, optionally each having an ear rest. In some embodiments, the one or more pods may be adapted to be mounted on each arm. In some embodiments, the bridge and/or arm rests may have an adjustable length.

[008] In some embodiments, the one or more pods may be adapted to be mounted on an arm by having an upper channel forming element and a lower channel forming element to form a channel to receive the arm. In some embodiments, each pod channel may have a resilient channel clip for holding the respective arm in the channel. In some embodiments, the one or more pods may have a pod release knob which can be operated so as to release the resilient channel clip such that the pod is moveable. The advantages of being able to remove the pod include that the device still be used with a patient who needs to be lain on one side.

[009] In some embodiments, the one or more pods may have an ear probe tube for connecting the pod to a patient's ear. In some embodiments, the ear probe tube may be mounted on a rotatable ear probe tube support. In some embodiments, the rotatable tube support may comprise a ball joint. Advantages of having a rotatable ear probe tube support include that there is more flexibility and more freedom of adjustment in the fitting of the ear probe tube to a patient's ear. In some embodiments, the pod may additionally comprise a power supply connector and a data connector. In some embodiments, the data connector may be a wired (e.g. USB data or serial port connector) or wireless connector to allow the pod to be connected to an external computer.

[0010] In some embodiments, each ear probe tube includes an aural ear probe. In some embodiments, the ear probe tube may be mounted on a rotatable support by a resilient releasable clip which is operated by a probe release knob. This is advantageous because it allows a patient to be scanned or X-rayed without the apparatus in the pod being damaged by the scanner or X-ray radiation. Since the pod can be released and easily removed, this also avoids the pod interfering and degrading these scanned images. The advantages of the rotatable ear probe tube support in combination with the repositionable pod include that it is possible to use the device 1 according to the invention with a wide variety of patient head- and ear-shapes.

[0011] In some embodiments, the pod comprises a tympanic intracranial pressure measuring apparatus which apparatus includes a block, a microphone, an amplifier, a diaphragm, a tube, an air reservoir, a pump, valves, an analogue/digital interface, and a computer.

[0012] According to the invention there is also provided a kit for measuring intracranial pressure using a tympanic measurement technique which kit comprises a pod which comprises an apparatus for measuring intracranial pressure using a tympanic measurement technique and an ear probe tube for connecting the pod to a patient's ear, a computer, and pressure variation equipment for applying a pre-determined externally induced intracranial pressure variation to a patient.

[0013] According to the invention there is further provided a method of diagnosing a medical condition by measuring a response to an externally induced intracranial pressure change on a patient in need of such diagnosis which method comprises the steps of:

a. providing a pod which comprises an apparatus for measuring intracranial pressure using a tympanic measurement technique and an ear probe tube for connecting the pod to a patient's ear, a computer and pressure variation equipment for applying a pre-determined externally induced intracranial pressure variation to a patient;

b. programming the computer to control the equipment to apply the pre-determined externally induced intracranial pressure variation;

c. programming the computer to detect any variation in intracranial pressure;

d. correlating any variation in intracranial pressure with the pre-determined externally induced intracranial pressure variation to diagnose intracranial health.

[0014] In some embodiments, a medical condition which may be diagnosed by the method according to the invention may be any medical condition which is associated with intracranial pressure such as ideopathic intracranial hypertension, brain trauma and disease, liver failure or a congestive heart problem. In some embodiments, the pod may be provided by a device according to the invention.

[0015] In some embodiments, the diagnosis of intracranial health in step (d) of the method comprises comparing the measured variation in intracranial pressure with a reference variation in intracranial pressure. In some embodiments, the diagnosis of intracranial health in step (d) of the method comprises comparing the measured variation in intracranial pressure in one ear of the patient with the measured variation in intracranial pressure in the other ear of the patient to determine whether the degree of variation is symmetrical. Advantages of this method step include that an asymmetric response may indicate brain lesion or other morbidity on one side of the patient's cranium.

[0016] In some embodiments, the pressure variation equipment for applying a pre-determined externally induced intracranial pressure variation to the patient comprises a rotatable bed and an actuator. In some embodiments, the variation in intracranial pressure may be measured by a computer in a pod of the device. In some embodiments, the rotatable bed may comprise an actuator and a bed which may be tilted by a pre-determined amount by the actuator.

[0017] In some embodiments, the computer has a display device and an input device. In some embodiments, the computer is connected to each pod of the device by a wired connector or wirelessly. In some embodiments, the actuator is mounted on the bed such that it can be controlled by the computer to rotate the bed.

[0018] In some embodiments, the bed has an upper end for supporting a patient's head and a lower end for supporting a patient's feet. In some embodiments, the actuator is arranged on the bed such that the actuator can rotate the bed by raising and lowering its upper end in relation to its lower end to apply the pre-determined pressure variation. In some embodiments, the actuator may rotate the bed by applying a tilting motion to the bed.

[0019] The tympanic measurement technique provides a method which measures pressure waves directly and baseline pressure changes in terms of a mechanical effect that is closely linked to ICP and is largely dependent on changes in cerebral blood flow and outflow resistance. Furthermore, calibration of ICP on an individual patient is possible with the tympanic measurement technique.

[0020] The tympanic measurement technique depends on fluid pressure communication between the intracranial and inner ear fluid space, and onward transmission of this pressure through the middle ear. In the first instance, this will depend on an open connection between the intracranial and inner ear fluid spaces..

[0021] The invention will now be illustrated with reference to the following Figures of the accompanying drawings which are not intended to limit the scope of the claimed invention:

FIGURE 1A shows a schematic cross-sectional view of a device according to the invention;

FIGURE IB shows a schematic plan view of the device according to the invention;

FIGURE 2 shows a schematic side elevation of a pod for use in the device according to the invention;

FIGURE 3 shows a schematic diagram illustrating the apparatus in a pod for use in the device according to the invention; and

FIGURE 4A illustrates the conversion of a trace of ear-drum displacements into a stable baseline pressure record;

FIGURE 4B illustrates changes in the baseline intracranial pressure over a monitored 90 hour period;

FIGURE 4C illustrates corresponding short-term intracranial pressure fluctuations; and

FIGURE 5 shows a schematic plan view of a kit according to the invention.

[0022] A device according to the invention is indicated generally at 1 on Figures 1A, IB and 2. Device has a spectacle-shaped frame indicated generally at 2 including a pair of arms 3A,3B, ear rests 4A,4B, a bridge 5 shaped to fit across a patient's forehead and a nose rest 6. A pod 60A,60B is mounted on each arm 3A,3B. The advantages of providing the device 1 in the form of a spectacle-shaped frame 2 instead of a helmet or harness include that the device may more readily be used with a patient in an intensive care unit who may already have other sensors positioned on their heads. In an alternative embodiment, the arms 3A,3B and bridge 5 may have an adjustable length.

[0023] Each pod 60A,60B contains an apparatus 40 as illustrated in Figure 3. Pods 60A,60B each have an upper channel forming element 62A,62B and a lower channel forming element 64A,64B, pod release knob 66A,66B, ear probe tube 21A,21B, rotatable ear probe tube support 70A,70B, ear probe tube release knob 72A,72B, power supply connector 74A,74B and data connector 76A,76B. As an alternative to the data connector 76A,76B, the apparatus may have a wireless data connector such as a Wi-fi or Bluetooth connector.

[0024] The upper channel forming element 62A,62B and lower channel forming element 64A,64B form a channel 78A,78B for slidingly receiving a respective arm 3A,3B of the frame 2. Formed within each channel 78A,78B is a resilient clip (not shown) for holding the respective arm 3A,3B in the channel 78A,78B. Pod release knob 66A,66B is arranged so that it can be operated to release the resilient clip in channel 78A,78B such that the pod 60A,60B may be repositioned along the length of its arm 3A,3B or removed from its arm 3A,3B altogether. The advantages of being able to remove pod 60A,60B include that the device 1 may still be used with a patient who needs to be lain on one side.

[0025] Each ear probe tube 21A,21B terminates in an aural ear probe 20 which is illustrated in Figure 3. Ear probe tube 21A,21B is mounted on rotatable ear probe tube support 70A,70B in the form of a ball joint by a resilient releasable tube support clip (not shown). Ear probe tube release knob 72A,72B is arranged so that it can be operated to release the resilient releasable tube support clip such that the pod 60A,60B may be removed from its ear probe tube 21A,21B. This is advantageous because it allows a patient to be scanned or X-rayed without the apparatus in the pod 60A,60B being damaged by the scanner or X-ray radiation. Since the pod can be released and easily removed, this also avoids the pod interfering and degrading these scanned images. The advantages of the rotatable ear probe tube support 70A,70B in combination with the repositionable pod 60A,60B include that it is possible to use the device 1 according to the invention with a wide variety of patient head- and ear-shapes.

[0026] Apparatus for use in each of the pods 60A,60B of the device 1 according to the invention is indicated generally at 40 on Figure 3. Apparatus 40 includes a block 23, a microphone 30, an amplifier 36, a diaphragm 31, a tube 24, an air reservoir 25, a pump 26, valves 27,28, an analogue/digital interface 35, and a computer 34.

[0027] Computer 34 is connected to a display 37 such as a screen or projector and input device 38 such as a keyboard by means of data connector 66A,66B which may be in the form of a micro USB connector.

[0028] Aural probe 20 is connected by a flexible ear probe tube 21 to one end of a cross-bore 22 formed in block 23, The other end of the cross-bore 22 is connected by the flexible tube 24 to the air reservoir 25 fed by the pump 26.

[0029] The air reservoir 25 can be isolated from the tube 24, and thus the probe 20, by the solenoidoperated valve 27 and vented to atmosphere through solenoid operated valve 28.

[0030] The cross-bore 22 intersects and communicates with a main bore 29 formed in the block 23 to be perpendicular to cross-bore 22. At one end of the main bore 29 is a pressure transducer in the form of a microphone 30 of a kind known as D.C., i.e. having a response which extends from audio frequencies down to infrasonics. At the opposite end of the main bore 29 is a servo-controlled reference diaphragm 31, the function of which is to compensate for pressure variations produced by the eardrum (not shown) and thus allow eardrum displacement measurement to be facilitated since the volume displacement of the reference diaphragm is a known function of its input voltage. Reference is made to Patent Specification No. GB2075679B for a fuller understanding of the components of the apparatus so far described. The contents of GB2075679 insofar as they concern the description of the apparatus shown in Figure 1 are imported by reference.

[0031] At its end remote from the flexible ear probe tube 21 the ear probe 20 has a resilient cup 32 to make an air seal with the ear under test, and inbuilt into the probe 20 is a miniature loudspeaker 33 of the kind used in hearing aids. In this embodiment of the invention the loudspeaker 33 is used both for the ipsilateral acoustic stimulation which will enable responsive eardrum displacement to be measured and for generating the sound wave the reflection of which will be used to measure aural acoustic compliance.

[0032] A digital computer 34 is arranged to receive, process and record eardrum movement and aural compliance signals from an analogue-digital interface 35. This receives signals from the microphone 30 through a summing amplifier 36 which is balanced by digital servo control signals made by the computer through the interface 35 to remove the quiescent voltage produced by the air pressure currently prevailing in the tubes 21 and 24. By this means the eardrum displacement measurements will be unaffected by the said air pressure. The computer 34 also serves for the automatic determination of middle ear pressure by tympanometric means and control of the air pump 26 and sequencing of the valves Y1 and 28 such that during acoustic compliance and eardrum displacement measurements pressure on opposite sides of the eardrum under test is equalised and such that during eardrum displacement measurement the probe 20 is isolated from the air reservoir 25 by closure of the valve 27.

[0033] This ensures that the total enclosed volume is kept to a minimum as required by low volume flow measurement and furthermore that microphone 30 is isolated from inherent noise of the pump

26.

[0034] Patient and test information can be input to the computer 34 by the keyboard 38 and the computer displays its analysis of the input information in the form of intracranial fluid pressure traces on the visual display unit 37.

[0035] In use of the apparatus of Figure 3 to measure intracranial pressure using a tympanic measurement technique, the cup 32 makes an air seal with the patient's ear, whereupon the computer 34 effects tympanometry, i.e. it senses middle ear pressure and balances it with an equal pressure in the outer ear canal by suitable operation of the air pump 26. At predetermined intervals the loudspeaker 33 is caused to emit a sound wave which provides an acoustic stimulus of an intensity sufficient to cause contraction of the stapedial muscle. During one such emission motion of the eardrum as a result of subsequent contraction of the stapedial muscle is measured in terms of volume displacement by combined action of the microphone 30 acting as a pressure-sensitive transducer and servo control of the reference diaphragm 31 to compensate for pressure changes resulting from eardrum displacement. During this emission the function of tympanometry is disabled by the computer 34 and closure of the valve TI occurs. During a subsequent emission of an intensity below that sufficient to cause contraction of the stapedial muscle the valve 27 is opened and the computer 34 carries out the function of tympanometry.

[0036] The sound wave reflected from the eardrum under this test condition is converted by the microphone 30 into an electrical signal provided to the computer 34. Recordings of perturbations in the aural acoustic compliance due to fluctuations in the intracranial pressure are stored within the computer 34 and made continuously except during periods of rapid switching to ear drum movement measurement. A running ensemble average of nominally 20 records of ear drum movement are made at a frequency of nominally 2 records per minute. The ensemble averaged waveforms are digitally analysed and expressed in terms of one or more parameters which have a predetermined relationship with absolute intracranial pressure as obtained from prior clinical trials on a large subject population. These parameters may be built in to the computer 34 or input by the keyboard 38. After subtracting the measured middle ear pressure to yield an estimate of the absolute baseline intracranial pressure, running values of intracranial pressure and standard errors obtained by this method are displayed in real time as a serial trace by the visual display unit 37.

[0037] At any time the eardrum movement may be precisely calibrated in terms of relative or absolute intracranial pressure if measurements of the said movement have been made during known changes in the relative or absolute value of intracranial pressure. An example of this is the pressure change known to result from a controlled postural manoeuvre of the patient. Such information may be input to the computer 34 by the keyboard 38 and the pressure scales on the serial pressure display will immediately be updated accordingly. In practice such calibration may be achieved by recording eardrum movement under various conditions, for example during periods of known intracranial pressure normality, during periods of direct intracranial pressure measurement by surgical procedure or during a controlled manoeuvre of the subject's posture which provides a standardised and approximately known change in intracranial pressure.

[0038] Use of the apparatus 40 to measure intracranial pressure using a tympanic measurement technique is illustrated by the serial traces shown in Figure 4 which will now be explained.

[0039] The seven graphs shown in Figure 4a record movement of the eardrum and changes in the pattern of this movement for variations in the intracranial pressure. Measurements of ear drum motion for various times after the patient's admission, 0 hour, are shown. Measurements at times 6.00,15.00, 72.00 and 72.30 hours are real data from a patient with benign intracranial hypertension, which is a medical condition of raised intracranial fluid pressure. The remaining data of Figure 4a is included for the sake of simplicity without standard errors. Also for the sake of clarity recordings of baseline and short-term intracranial pressure fluctuations have not been mathematically combined as previously described.

[0040] The recorded eardrum movements result from contraction of the stapedius muscle brought about by a 1000 Hertz, 115 dB SPL acoustic stimulus, i.e. ipsilateral stimulation. The stimulus was of 500 ms duration and the graphs show ear drum motion from the time of stimulus switch-on indicated at 41 to the time of switch-off indicated at 42. Each graph represents an ensemble average of the eardrum motion for 15 repeats of this stimulus. The movement of the eardrum is expressed on the vertical axis 43 as a volume displacement measured in nanolitres (nl). A positive displacement value corresponds to an outward movement of the eardrum and a negative displacement value to an inward movement. Intracranial pressure has been quantified at the various times shown in terms of the mean displacement 44 of the eardrum (Vm) measured from the instant 45 of maximum inward displacement to the instant 42 of switch-off of the stimulus. These mean displacements (Vm) are derived using a computer algorithm and their values are initially transformed to provide a recording of the intracranial pressure as shown in Figure 4b, using predetermined relationships obtained during prior clinical trials on a large subject population. Figure 4b shows various changes in the base-line intracranial pressure over the monitored 90 hour period. Figure 4c illustrates the corresponding short-term intracranial pressure fluctuations measured by the acoustic compliance means and calibrated in terms of said pressure by first calibrating in terms of eardrum displacement as previously described.

[0041] An exploratory lumbar-puncture was undertaken on this patient to confirm the medical diagnosis of raised intracranial fluid pressure and Figures 4b and 4c show the resulting pressure change at 46 and 52, respectively. At this time an estimate of the absolute intracranial pressure was obtained as 350 mm saline and the present invention allows this to be entered by means of the keyboard 38 with the result that the absolute pressure scale of Figure 4b is realigned. After 48 hours a lumbar-shunt was surgically inserted into the patient and this successfully reduced the intracranial pressure to within normal limits as indicated at 47 and 53.

[0042] After 72 hours the measurement method was finally calibrated using an actual controlled change in pressure indicated at 48 and 54, brought about by a postural manoeuvre of the patient known to bring about an increase in pressure by nominally 100 mm saline as indicated at 49 in Figure 4b. Again the estimate of pressure change was entered by means of the keyboard 38 and this facilitated final adjustment of both the absolute and relative intracranial pressure scales for both the base line of Figure 4b and the short-term fluctuations of Figure 4c.

[0043] A kit according to the invention is indicated generally at 80 on Figure 5. Kit 80 includes a device 1 according to the invention as illustrated in Figures 1A, IB and 2, a computer 82 and bed 90. Computer 82 has a display device 37 and an input device 38 and is connected by connectors 67A,67B to the pods 60A,50B of device 1. Bed 90 has an actuator 92 which is connected to computer 82 by connector 94. Bed 90 has an upper end 93 for supporting a patient's head and a lower end 95 for supporting a patient's feet. Actuator 92 is arranged on bed 90 such that actuator 92 can tilt bed 90 by raising and lowering upper end 93 in relation to lower end 95. In an alternative embodiment, kit 80 comprises a pod 50A instead of device 1.

[0044] In use, kit 80 can be used to diagnose a medical condition by measuring its response to an externally induced pressure change. Computer 82 may be programmed to operate actuator 92 to tilt bed 90 by a pre-determined known amount at a pre-determined frequency. At same time, the computer is programmed to detect any variation in ICP as measured by computer 34A,34B in pods 60A,60B and to correlate that variation with the pre-determined rotation frequency using a suitable function, for example assuming a 1:1 correlation.

Claims

1. A device having a spectacle-shaped frame for supporting one or more pods wherein each pod comprises an apparatus for measuring intracranial pressure using a tympanic measurement technique and an ear probe tube for connecting the pod to a patient's ear.

2. A device as defined in Claim 1 wherein the frame comprises a bridge, a nose rest and a pair of arms; preferably the pair of arms each have an ear rest; preferably the bridge and/or arm rests have an adjustable length.

3. A device as defined in Claim 1 or Claim 2 wherein the one or more pods are adapted to be mounted on each arm.

4. A device as defined in any one of the preceding Claims wherein the one or more pods form a channel to receive an arm of the frame; preferably the one or more pods have an upper channel forming element and a lower channel forming element to form the channel to receive the arm.

5. A device as defined in Claim 4 wherein each pod channel has a resilient channel clip for holding an arm in the channel.

6. A device as defined in any one of the preceding Claims wherein the one or more pods have a pod release knob to release the pod from the frame.

7. A device as defined in Claim 5 wherein the one or more pods have a release knob which operates the clip so as to release the pod from the frame.

8. A device as defined in any one of the preceding Claims wherein the ear probe tube is mounted on a rotatable ear probe tube support; preferably the rotatable ear probe tube support comprises a ball joint.

9. A device as defined in any one of the preceding Claims wherein the one or more pods have a probe release knob to release the ear probe tube from the pod.

10. A device as defined in Claim 9 wherein the ear probe tube is mounted on a rotatable support by a resilient releasable clip which is operated by the probe release knob.

11. A kit for diagnosing a medical condition which kit comprises a pod which comprises an apparatus for measuring intracranial pressure using a tympanic measurement technique and an ear probe tube for connecting the pod to a patient's ear, a computer, and pressure variation equipment for applying a pre-determined externally induced intracranial pressure variation to a patient.

12. A kit as defined in Claim 11 wherein the pressure variation equipment comprises a rotatable bed and an actuator; preferably the actuator is mounted on the bed such that it can be controlled by

5 the computer to rotate the bed to apply a pre-determined pressure variation to the patient.

13. A kit as defined in Claim 12 wherein the bed has an upper end for supporting a patient's head and a lower end for supporting a patient's feet; preferably the actuator is arranged on the bed such that the actuator can tilt the bed by raising and lowering its upper end in relation to its lower end to apply the pre-determined pressure variation.

10

14. A kit as defined in any one of Claims 11 to 13 wherein the pod is provided by a device as defined in any one of claims 1 to 10.

15. A method of diagnosing a medical condition by measuring a response to an externally induced intracranial pressure change on a patient in need of such diagnosis which method comprises the steps of:

15 (a) providing a pod which comprises an apparatus for measuring intracranial pressure using a tympanic measurement technique and an ear probe tube for connecting the pod to a patient's ear, a computer and equipment for applying a pre-determined externally induced intracranial pressure variation to a patient;

(b) programming the computer to control the equipment to apply the pre-determined

20 externally induced intracranial pressure variation;

(c) programming the computer to detect any variation in intracranial pressure;

(d) correlating any variation in intracranial pressure with the pre-determined externally induced intracranial pressure variation to diagnose intracranial health.

16. A method as defined in Claim 15 wherein step (d) comprises comparing the measured

25 variation in intracranial pressure with a reference variation in intracranial pressure.

17. A method as defined in Claim 16 wherein step (d) comprises comparing the measured variation in intracranial pressure in one ear of the patient with the measured variation in intracranial pressure in the other ear of the patient to determine whether the degree of variation is symmetrical.

18.

A method as defined in any one of claims 15 to 17 wherein the pod is provided by a device as defined in any one of claims 1 to 10.

Intellectual

Property

Office

Application No: GB1707266.1