Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
  • A61B5/021—Measuring pressure in heart or blood vessels
  • A61B5/022—Measuring pressure in heart or blood vessels by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
  • A61B5/02233—Occluders specially adapted therefor
  • A61B5/02241—Occluders specially adapted therefor of small dimensions, e.g. adapted to fingers
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
  • A61B5/6801—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be attached to or worn on the body surface
  • A61B5/6813—Specially adapted to be attached to a specific body part
  • A61B5/6825—Hand
  • A61B5/6826—Finger
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B2562/00—Details of sensors; Constructional details of sensor housings or probes; Accessories for sensors
  • A61B2562/02—Details of sensors specially adapted for in-vivo measurements
  • A61B2562/0247—Pressure sensors

Definitions

• the present invention relates generally to a system for measuring an arterial pulse, and more particularly to a means by which arterial pulse wave form can be continuously monitored with a noninvasive device that makes direct mechanical contact with the user's finger but without occluding blood flow in the finger.
• the pressure pulse the mechanical representation of the blood flowing in the artery, is generally believed to be best detected at the classic pressure points that are well known and whose locations are widely published in the literature. At these points the artery is close to the surface of the skin so that with application of light constrictive pressure (palpation), the pulsations caused by the heartbeat can be sensed mechanically as pulsations in the constrictive force.
• a hydrostatic finger cuff for blood flow property analysis which includes an elongated substrate member which has a pair of opposing long edges and a pair of opposing short edges.
• the hydrostatic finger cuff is configured to form a frustoconical shell when the ends of the cuff are overlapped and releasably connected together.
• the interior of the frustoconical shell conforms to the shape of the middle phalange of a finger or the first phalange of the thumb. If a finger is used it is preferably the middle finder, in the region from the distal joint to the proximal joint.
• the finger cuff is used by one patient and is disposed of after being used by one patient.
• the finger cuff may be disposed of after a period of use by a patient and replaced with a new, unused finger cuff for further use by the patient.
• the pair of opposing long edges has a radius of curvature in the range from about 7 inches to about 13 inches.
• the first of the long side edges has a radius of curvature in the range from 10 inches about 13 inches and a second of the long side edges has a radius of curvature in the range from 10 inches about 7 inches.
• the first of the long side edges has a radius of curvature in the range from 10 inches about 12 inches and a second of the long side edges has a radius of curvature in the range from 10 inches about 8 inches.
• an inflatable member mounted on the obverse side of the elongated member and the inflatable member has a
• a tube is fixed to the inflatable member and is in pneumatic communication with the interior of the inflatable member.
• the inflatable member is preferably a urethane membrane peripherally sealed to a urethane substrate member.
• One part of a two part connector, preferable one of a hook and loop member is affixed to the obverse side of the elongated member and positioned proximate a first side edge of the elongated substrate member.
• the inflatable member is positioned proximate a second side edge of the elongated member, and the other of a hook and loop member is affixed to the reverse side of the elongated member in the region of the inflatable member.
• the loop member is proximate the inflatable member and the hook member is distal the inflatable member, thus optimizing the ability of the cuff to conform to the contour of the user's finger when the cuff is wrapped around the finger.
• a releasable, reusable adhesive can be used in place of the hook and loop connector.
• PSAs Pressure sensitive adhesives
• U.S. Pat. 6,040,028 and 5,102,714 Japanese patents, JP 08 188 755 and JP 06 279 741 .
• the PSA provide the advantage of enabling better conformation of the cuff to the curvature of the finger.
• the substrate member, the inflatable member, and the tube are formed from polyurethane.
• the long side edges of the elongated substrate member have a length in the range from 3 inches about 6 inches.
• a first of the long side edges of an elongated substrate member has a radius of curvature in the range from 10 inches about 12 inches and a second of the long side edges has a radius of curvature in the range from 10 inches about 8 inches.
• the inflatable member is substantially rectangular and has an active surface area in the range from 0.9 to 2.5 square inches.
• the inflatable member is substantially rectangular and has an active surface area of at least 1 .5 square inches, and preferably, an active surface area in the range from about 1 .5 to 2.5 square inches in order to accommodate a large finger.
• the inflatable member is substantially rectangular and has an active surface area in the range from about 0.9 to 1 .3 square inches.
• the first side of the active area of the inflatable member has a width that is slightly less that the distance between the distal joint of a finger and the proximal joint of the finger, and preferably extends from proximate the distal joint of a finger to a point proximate the proximal joint of the finger.
• the length of the first side is in the range from .6 inches to 1 .2 inches in order to accommodate a small finger and in the range froml .25 inches to 0.88 inches to accommodate a large finger.
• the finger is the user's middle finger.
• the inflatable member is substantially rectangular and has a length to width ration in the range from 1 .5 to 1 , to 2.5 to one, preferably it has a length to width ration in the range from 1 .75 to 1 to 2.25 to 1 , and most preferably, about 2 to 1 .
• the active area of the inflatable member has an edge whose length is in the range from .63 inches to .88 inches and a second side or edge whose length is in the range from 1 inch to 1 .5 inches.
• a first side of the active area of the inflatable member has a length in the range from 1 .25 inches to 0.88 inches and a second side of the active area of the inflatable member has a length in the range from 2.25 inches to 1 .5 inches.
• the inflatable member is preferably long enough to cover at least 1 ⁇ 2 and most preferably, at least 2/3 of the circumference of the middle flange of the finger, with the middle finger being the preferred finger.
• the tube has an inside diameter in the range from .05 to .075 inches in order to provide the preferred level of fluid communication between the inflatable member and a pressure sensor.
• the inflatable member must be completely circumscribe the finger and provide substantially uniform contact across the entire length of a phalange, in particular, the middle phalange of the middle finger. This is in contrast with optical sensors and palpating devices which in essence, focus on the region of the finger's artery.
• a hydrostatic finger cuff for blood flow property analysis comprises an elongated substrate member, an inflatable member mounted on the obverse side of the elongated member, a tube fixed to the inflatable member and in pneumatic communication with the interior of the inflatable member, one of a hook and loop member affixed to the obverse side of the elongated member and positioned proximate a first side edge of the elongated substrate member, and a pressure relief member.
• the pressure relief member is in fluid communication with the inflatable member, and is set to open and release pressure at a pressure level no higher than 1 .2 psi.
• the tube has a terminal end proximate the inflatable member and a terminal end distal the inflatable member
• the pressure relief member is a poppet valve affixed to the tube at a point between the proximal terminal end and the distal terminal end and is set to open and release pressure at a pressure level of up to 1 .2 psi and most preferably at no greater than 1 .1 psi.
• the poppet valve can be attached to the tube by a ⁇ " or "T" connector.
• the pressure relief member is a frangible member affixed to the substrate member and in fluid communication with the interior of the inflatable member.
• the frangible member can be a membrane that is designed to open and release pressure at a pressure level of up to 1 .2 psi. and preferably at a pressure no greater than 1 .1 psi.
• a finger cuff device which comprises an elongated substrate member, having an obverse side and a reverse side, an inflatable member mounted on the obverse side of the elongated member, the inflatable member having a pressurizable interior region, a tube fixed to the inflatable member and in pneumatic communication with the interior of the inflatable member, one side of a connector member is affixed to the obverse side of the elongated member and positioned proximate a first side edge of the elongated substrate member, the inflatable member is positioned proximate a second side edge of the elongated member, and the other of part of the connector member is affixed to the reverse side of the elongated member.
• the monitoring process comprises the steps of: a- encircling a user's finger with the finger cuff, b- affixed the two parts of the connector member together such that a cylindrical cuff is formed around a middle phalange of a finger and the inflatable member is in circumferential contact with the finger of the user, c- inflating the inflatable member to a pressure below the user's diastolic pressure, and d- generating pressure fluctuations which correspond to the user's blood pressure.
• the inflatable member is inflated to a pressure in the range from 30 psi to 60 psi and most preferably to a pressure in the range from 40 psi to 50 psi.
• pressure pulses are transmitting from the inflatable member to a pressure sensor, and an analog output from the pressure sensor is converted to a digital signal.
• the digital signal to a computer where the digital signal is converted to a pulse wave form and the pulse wave form is converted to blood pressure values.
• Figure 1 is a side view of the unwrapped finger cuff in accordance with the present invention.
• Figure 2 is a side view of the wrapped finger cuff in accordance with the present invention.
• Figure 3 is a side view of an alternate embodiment of an unwrapped finger cuff in accordance with the present invention.
• Figure 4 is a face view of the unwrapped finger cuff in accordance with the present invention.
• Figure 5 is a face view of an additional embodiment unwrapped finger cuff in accordance with the present invention.
• Figure 6 is a dorsal perspective view of the finger cuff on a user's hand in accordance with the present invention.
• Figure 7 is a volar perspective view of the wrapped finger cuff illustrating the conical configuration in accordance with the present invention.
• Figure 8 is a perspective view of the finger cuff in its conical form, in accordance with the present invention.
• Figure 9 is a volar perspective view of the wrapped finger cuff placed on the first phalange of the user's thumb in accordance with the present invention.
• Figure 10 is a plan view of an inflatable membrane and tube in accordance with an embodiment in accordance with the present invention.
• Figure 1 1 is a plan view of an alternate embodiment of the invention in accordance with the present invention.
• Figure 12 is a plan view of an alternate inflatable membrane and tube in accordance with another embodiment of the present invention.
• piezoelectricity refers to ability of crystals and certain ceramic materials to generate a voltage in response to applied mechanical stress.
• the piezoelectric effect is reversible in that piezoelectric crystals, when subjected to an externally applied voltage, can change shape by a small amount. (For instance, the deformation is about 0.1 % of the original dimension in piezo element.)
• the effect finds useful applications such as the production and detection of sound, generation of high voltages, electronic frequency generation, microbalance, and ultra-fine focusing of optical assemblies.
• piezo element refers to any material that has capability of generating piezoelectricity.
• the term "plethysmograph” refers to an instrument that measures variations in the size of an organ or body part on the basis of the amount of blood passing through or present in the part.
• PZT refers to a piezo element, as for example, one of lead zirconate titanate, a material that shows a marked piezoelectric effect as well as any other electroceramic that contains the properties necessary achieve the results set forth herein.
• the term "transimpedance amplifier” refers to a circuit for converting current input into voltage output.
• a typical situation is the measuring of current using instruments having voltage inputs.
• a current-to- voltage converter is a circuit that performs current to voltage transformation. In electronic circuitry operating at signal voltages, it usually changes the electric attribute carrying information from current to voltage.
• the active version of the circuit is also referred to as a transresistance or transimpedance amplifier.
• the term "light coupling”, as employed herein, refers to a minimal coupling level.
• the coupling is sufficient to provide a firm contact between the cuff and the finger, but producing no more than minimal interference with the flow of blood in the artery of the finger.
• the term "firm contact” as employed herein refers to a sufficient contact between the user's finger and the bladder to generate an analogue signal that corresponds to the user's blood pressure.
• US patent 4726382 discloses a finger cuff in which "[o]uter cuff label 18 is sufficiently unstretchable so as to allow inflation of the inflatable bladder 12 to affect circulation of blood within the arterial system of the patient's finger". (See column 4, lines 51 -59)
• the term "rectangular” as employed herein refers to any generally rectangular shape inclusive of a rectangle has chamfered corners, or filleted corners as in what is commonly referred to as “race track” shape.
• the term “finger”, as employed herein refers to all of the five digits of the mammalian hand. Specific reference to particular digits is made where referencing optimum usage however generic use of the term finger can indicate optimum and non-optimum placement of the finger cuff.
• the present invention relates to wireless and noninvasive physiological monitoring system in the form of a hydrostatic finger cuff for measuring heart rate variability (HRV), blood pressure, hypovolemia, hypervolemia, inter beat-interval, abnormal patterns, and other physiological cycles.
• Monitored data can be stored within the device for later download using a connection to a PDA or PC, via a connection such as USB, Bluetooth, etc. Alternatively the data can be sent to the receiving device in real time.
• the incorporated relative pressure sensor must have sufficient sensitivity that little deformation is necessary to couple the sensor to the pulse, thereby enabling the device to be used for many hours, or even days, on a continuous basis.
• a standard, commercially available pressure sensor such as a relative (gauge) or absolute sensor, can be used to keep the pressure in the cuff constant and is no different from a manometer. Essentially, it is used as a gauge pressure sensor since it is open to the atmosphere on the other side, measuring static pressure. However, as the sole gauge, it does a poor job of measuring changes in pressure unless they are very, very slow, like atmospheric pressure.
• a second pressure sensor is used to measure the time rate of change of pressure. It will not measure static pressure, either absolute or gauge. Piezo disks mounted in a ring have been used to measure the pulse pressure wave. They were shoved up against the radial artery and produced a wave form of the arterial pulse. The problem with these was that minor motion caused the loss of subsequent beats for maybe six to ten seconds. It is possible to make them settle very quickly, but the components become very large and not amenable to small devices. It has been found that by using a transimpedance amplifier the settling time can be reduced to less than one heart beat cycle with tiny components. This produces the time derivative of the pulse pressure pulse.
• the pulse decomposition analysis principle is used to analyze the arterial pressure pulse.
• the finger cuff provides continuous pressure readings by deconvolving the pulse waveform into its constituent component pulses by a process known as Pulse Decomposition Analysis (PDA).
• PDA Pulse Decomposition Analysis
• the design of the finger cuff of the present invention enables the device to be used without significantly affecting the flow of blood because the inflation of the cuff need only be sufficient to produce a light coupling to the arteries of the finger.
• the finger/pressure cuff does not change the inner diameter of the artery at all and therefore does not affect the flow of blood.
• the pressure in the cuff is preferably less than the diastolic pressure in the artery, and preferably, no greater than about 50 psi.
• the lower limit of the pressure is sufficiently high to enable the light coupling with the artery but sufficiently low that the interference with the blood flow, if any, is minimal.
• Minimal interference means that the cuff can be used for extended periods of time, that is, for multiple hours or days.
• the finger cuff is wrapped around the measurement site and inflated to a low pressure near, for example, to 50 mmHg to increase the contact pressure.
• the pulse then causes a small variation in the internal pressure in the cuff due to a very small volume change as the blood surges past the site.
• the pressure is maintained below the diastolic pressure and is preferably in the range from 30 to 70 mmHg and most preferably in the range from about 35 to 55 mmHg.
• the pressure is determined on the basis of maintaining good contact with the finger, or more specifically, the pulse wave.
• the cuff surrounds the phalange and applies uniform circumferential pressure.
• Maintaining a constant or consistent pressure is not necessary but it is essential to set a maximum level for the pressure so as to avoid occluding the blood flow.
• a minimum pressure is critical from the standpoint of maintaining good contact with the finger in order to sense the pulse pressure wave.
• a piezoelectric buzzer element is attached across the inputs and the gain (Transimpedance) is varied a little to adjust the signal level to fit the finger cuff.
• the bandwidth of the device is adjusted slightly to remove sensitivity to outside noise sources.
• the signal bandwidth contains the fundamental at about 1 Hz and the signal features which extend to about 60 Hz.
• a pneumatic coupling is provided between the finger cuff and the analog signal generator.
• the finger cuff will work on any finger, the optimum site for the finger cuff has been found to be the first phalange of the thumb. Extremely accurate results can also be obtained using the middle phalange of a finger, preferably the middle finger.
• the thumb provides optimal results since, as known in the medical arts, the thumb contains the princeps pollicis artery which arises from the radial artery.
• the other fingers have the proper palmer digital arteries and arise from the ulnar artery.
• the mean diameter of the radial artery is 28% larger than the ulnar artery (Riekkinen HV, Karkola KO, Kankainen A.
• the radial artery is larger than the ulnar.
• Ann Thorac Surg 2003;75:882-4 This means the blood flowing to the thumb artery is greater that he blood flowing to the other digits.
• the radial artery serves only a single digit, while the ulnar artery serves four digits.
• the use of the thumb has now been found to be advantages because temperature appears to have a relationship to the functioning of the finger cuff device.
• the use of the thumb is advantageous because the size of the artery also directly relates to temperature. It is well known that Raynaud's disease, low thyroid levels, anemia, diabetes, heart disease, cancer, arthritis, carpal tunnel, tendonitis and many other medical conditions can produce cold hands. That is because extreme
• the thumb bladder although the same as the finger bladder, it-does not suffer the mechanical noise problems that arise from the carpal tunnel. Almost any movement of any part of the arm causes some rubbing between taught tendons inside the tunnel producing low frequency noise.
• This low frequency clatter has spectral power in the same band as the heartbeat pulse, about .01 to 30 Hz, abounds and cannot be always completely filtered out.
• the analog signal generator is preferable a piezo element, although other elements can be used that produce the same result, mounted in a pressure housing which includes a pressure pump and can include an analog to digital converter, a transimpedance amplifier, a data storage member, and a signal transmitter.
• the data storage member can include a solid-state memory device.
• a preferred method essentially shorts the surfaces of the piezo and measures the current produced as the charge migrates due to the change in pressure.
• the amplifier in this case, is called a Transimpedance amplifier because it produces a voltage change proportional to the current at its input. (Impedance is Volts /
• the finger cuff departs from prior art devices in that it does not attempt to palpate the finger. Pressure is not applied to the finger artery but rather, the finger is ringed by a cuff which circumferentially applies pressure to the finger, that is, it squeezes the finger.
• the finger cuff is entirely constructed from polyurethane.
• Polyurethane film (two thousands of an inch thick) that is bonded to a 5-7 mils polyurethane outer layer of hook and loop material, preferably in a one-step operation using radio frequency welding. This helps to make the cuffs inexpensive because there is little labor component needed in construction.
• the outer layer to which the inner layer is bonded is the loop section of the hook and loop material.
• polyurethane film is known of as a very skin friendly material and used for disposable upper arm cuffs in sphygmomanometers as well as sometimes used as disposable sheets in hospitals, is not used frequently for hook and loop connectors.
• the polyurethane hook and loop system allows only for about a hundred make and break uses before the system becomes weak and undependable.
• hook and loop materials other than polyurethane can last for thousands of make and break connections and these are found on garments, and in similar applications.
• an adjustable connector such as hook and loop material
• the expansion of the bladder is not used to accommodate a loose fitted cuff but rather to make a minor adjustment to achieve a firm contact between the bladder and the user's finger.
• FIG. 1 and 2 shows a finger cuff 100 having a hook section 104 affixed to interior side A and a loop section 106 affixed to exterior side B.
• the hook section 104 and the loop section 106 are affixed not only at opposite sides but also at either end of the substrate member 102 and are used to secure the cuff 100.
• An inflatable sensing member 1 10 is positioned on the interior side A of the substrate 102 approximately opposite the loop section 106and contacts the user's finger.
• the sensing member 1 10 consists of an inflatable membrane 1 16 and tube 1 14. The periphery of the inflatable membrane 1 16 is fused to the substrate member 102, as indicated at edges 1 12 and 1 13.
• the inflatable member 1 16 is configured to enable the sealed interior region 1 18 formed by the membrane 1 16 and the substrate 102, to be pressurized to form, in conjunction with the tube 1 14, the pressure sensor 1 10.
• the tube 1 14 is in pneumatic communication with the interior region 1 18 and the electronic components housing 600 of Figure 6.
• the tube 1 14 is preferably urethane with an interior diameter of about one- sixteenth (.0625) inch and an exterior diameter of about one eight (.125) inch.
• the cuff 200 uses a sensing member 210 constructed the same as the sensing unit 1 10 of Figures 1 and 2. In this embodiment, however, the loop section 206 extends along the entire length of the substrate 202.
• the hook section 204 preferably is only at the end of the substrate 202 to prevent the hook section 204 from coming into contact with the user's skin and causing discomfort.
• FIGs 4 and 5 the face of two embodiments of the cuff disclosed herein are illustrated.
• the cuff 400 has the hook material 408 at one end of the substrate 420 and the sensing member 410 at the opposite end.
• the inflatable membrane 405 is shown with the inflatable portion 406 sealed along its periphery 404.
• the tube 402 can also be provided with a lock 410 that provides a back up to prevent the tube 402 from being accidentally removed from the inflated portion 406.
• the tube 402 is sealed between the substrate 420 and the inflatable membrane 405 at the peripheral region 404, and the lock 410 is another of the safety redundancies provided within the system.
• the lock 410 serves to resist the tube being pulled out of the inflatable region 406 formed by the substrate 420 and the inflatable membrane 405.
• the substrate component of the finger cuff is preferably not rectangular but rather has two opposing curved edges 430 and 440, whose radius of curvature "R" is in the range from about 13 inches to about 7 inches.
• the substrate 520 has the hook portion 508 at the end opposite that of the sensing member 510.
• the sealed portion 504 is at the periphery of the inflatable membrane 505. It is highly preferable, that the sealed portion 504 securely seals the tube 502 that extends into the interior of the inflatable membrane 506.
• the tube 502 has a lock section 512, in this instance a button shape, within the inflatable area.
• the edge 530 of the substrate 520 has a radius of curvature in the range from about 10 to 13, and most preferably 10 to 12 inches.
• the edge 540 of the substrate member 520 preferably has a radius of curvature in the range from about 10 to 7 inches and most preferably a radius of curvature in the range from about 10 to 8 inches.
• the radius of curvature required for a proper fit for a male with large fingers is significantly greater than that for a woman with small fingers.
• the radius of curvature required for a proper fit for a woman with large fingers is significantly greater than that for a child with small fingers.
• the need for the finger cuff to be curved is due to the importance of the cuff to conform to the taper of the user's finger in order to provide the essential firm contact between the bladder and the finger uniformly across the area of the bladder, in particular, the full length of the region of the finger between the proximal and distal joint which is in contact with the bladder member 505.
• the cuffs need to be very flexible to conform to the finger without creases or air pockets.
• the length of the tube is preferably no less than several inches or more. As the tube provides communication between the cuff and the recording/storage device the length can vary depending on application. In some embodiments, the tube can be extendable through airtight connectors to enable extension at time of application.
• the length of the short side "B" of the inflatable region of the membrane 505, as seen in Figure 5, is preferably in the range from about .63 to 1 .5 inches.
• the width "C" of the substrate member 520 is preferably in the range from about 1 1/8 to 1 1 ⁇ 2 inches.
• the width "D" between the two long sides of the inflatable region 506 of the membrane 505 is in the range from .6 to 1 .25 inches and is selected to correlate to the distance between the distal and proximal joints of the middle phalange of a finger, preferably, the middle finger.
• the width ⁇ " of the hook area 508 is preferably in the range from 1 ⁇ 2 to 3 ⁇ 4 of an inch.
• the loop region 508 of the hook and loop member is preferably larger than the region of the inflatable member.
• the radius of curvature of the substrate edge 540 can be in the range from 7 to 13 inches and the radius of curvature of the shorter the long substrate edges can be in the 7 to 10 inches and 10 to 13 inches for the longer of the long substrate edges.
• the inflatable member is preferably has an active surface area in the range from 0.9 to 2.5 square inches.
• the active surface area is in the range from about 1 .5 to 2 square inches.
• the active surface area is in the range from about 0.9 to 1 .3 square inches.
• the distance "R" between the two short sides of the substrate member can be in the range from 3 to 6 inches, and preferably is in the range from 33 ⁇ 4 to 51 ⁇ 4 inches.
• Reference to the length of a side of the inflatable region or the substrate member is intended to be inclusive of the distance between two opposing walls of a filleted or chamfered rectangle.
• Figure 6A the cuff 500 is seen on the middle phalange of the user's middle finger with the tube 502 leading to a signal processing and data recording and storage device 600.
• the data can be sent to any device used to gather and analyze data within the facility.
• the transfer of data can be through any means known at the time in the computer arts and applicable to the application.
• the data can be analyzed and read directly from the recording device 600.
• the finger has a bone in the center and two arteries, one on each side.
• the cuff 500 is placed on the user's finger with the flexible bladder in contact with the two arteries.
• the cylindri cally pressurized cuff squeezes the finger tissue and unloads the finger arteries. This eliminates the elasticity function of the artery with the bladder around the finger then providing the elastic restoring force that is, the bladder becomes the elastic arterial wall.
• the bladder also now contains the pulse pressure wave. No artery is squeezed against a bone, no circulation is impeded and no palpation method is used. As previously stated, the bladder has been pressurized to below the diastolic pressure. By way of extreme contrast, a brachial artery cuff plethysmograph must be pressurized to a level above the arterial systolic pressure.
• At least two failsafe mechanisms are employed to prevent over inflation of the cuff, which would kill the finger in extended use.
• the structure of the present invention has been designed to be an
• the present invention employs a normally closed valve in order to conserve battery power. In this case the excitation initiates a venting action, releasing the pressure in the bladder.
• a general power failure would not passively result in the release the pressure in the bladder. Therefore, as a first failsafe step, the absolute pressure is read four times a second and can shut the whole process down using software commands and controls. As stated heretofore, the set point for bladder pressurization is about 50 mmHg, well below diastolic pressure and therefore not considered to be injurious to a finger. It is preferable that control of the set point is via the software; however a maximum set point can be programmed in for additional safety.
• a second failsafe is a poppet valve that simply opens when a predetermined maximum pressure is reached.
• a poppet valve In a conventional automatic sphygmomanometer there is no need for a poppet valve because the cuff is holding back pressure, which can be as high as 200 mmHg or more, and, if the power failed, it would open and release the pressure alleviating any danger to the wearer.
• the prior art cuff uses a normally open valve and excitation of the electrical version closes the valve.
• the present invention employs a normally closed valve, the opposite of prior art cuffs.
• the poppet valve used herein is set at about 1 to about 1 .2 PSI. Thus, if the pressure increased beyond a predetermined level, the poppet valve would release it passively, without electrical control.
• FIG 8 the cuff 500 is seen without a user's finger.
• the tube 502 extends from the membrane 505 and the hook 508 has been affixed to the loop 506.
• the poppet valve 700 is affixed to a manifold which is illustrated as a T-connector 704 that is inserted between the tubing 502 that leads from the interior of the inflatable region 505 and the tubing 702 that leads to a pump located in the electronic device housing 600.
• a T-connector 704 is used in this embodiment, any other methods for situating the poppet valve 700 along the tubing can be used and will be known to those skilled in the art, as for example, through the use of a ⁇ " shaped manifold.
• the inflatable area 742 contains the tubing 722, and respective lock 710, which leads to the electronic device 600 (not illustrated). Additionally a second tube 703 extends into the inflatable area 742 where it is equipped with lock 712. The opposing end of the tube 703 leads to a poppet valve 720. It is noted that more safe guards translate into lower insurance premiums and thus lower costs. As previously noted the tubes 703 and 722 are preferably fused to the urethane inflatable member and the urethane substrate member.
• a poppet valve can contain a stainless steel spring and ball device mounted inside a stainless steel tube with barbs on the outside of the stainless tube made to grip the inside of a polymeric tube, such as 722 and/or 703.
• the valve assembly preferably has a precision valve seat to prevent leakage.
• a poppet valve can additionally, or alternatively, be included within the electronic device housing 600.
• a polymeric part, single use valve can be provided in association with the cuff.
• a polymeric membrane would fail and release the pressure, rendering the cuff unusable at this point.
• the finger cuffs are reusable, but for health reason can be disposable, in the sense that they are intended to be used only by a single user, such as a single patient in a hospital. The user might use the cuff for an extensive period of time and might remove the cuff temporally, as for example, when bathing or washing hands, but this is considered a single use.
• a user might dispose of a finger cuff if it became soiled, and would then use a new cuff.
• the pressure relief membrane 810 can be formed directly on the bladder (not show), though the contact between the frangible membrane 810 and the finger can affect adversely affect the pressure which is required to burst the membrane.
• the frangible membrane 810 is formed on the substrate member 808 and an opening 81 1 is provided in the loop material 804. Bursting of the membrane 810 will cause air to be released between the hook and the loop 804 sections of the cuff, since the hook and loop 804 system does not form an air tight seal.
• an elongated slot 812 can be provided in the substrate 808 in the region where the substrate member overlies the membrane 810 when the cuff 800 is in use. This enables the pressure to be released more rapidly in the event of membrane rupture.
• the hook section of the fastener can be provided with a plurality of air passage holes which serve the same function as the single elongated opening 812.
• the rupture membranes are manufactured as rectangular panels (rupture panels or vent panels). Device sizes preferably range under 1 ⁇ 4 inch and can be constructed from various materials, in particular, polymeric films that can rupture at a pressure under two psi.
• frangible membrane can be mounted in the manner of the poppet valve 700 of Figure 10, or poppet valve 720 of Figure 1 1 .
• the basic components of the algorithm are 1 - a peak finder that identifies heartbeats in the derivative data stream, 2- a differentiator that produces the second derivative of the detected heart beat which is then used to find the inversions corresponding to the locations of the component pulses, 3- a digital integrator, implemented as a Bessel filter, that generates the integrated pulse wave form from the differentiated raw signal stream, and from which relative component pulse amplitudes are determined and 4- a low-pass filter that enables identification of the primary systolic peak. Furthermore the frequency content of the data stream is continuously analyzed in order to calculate signal to noise (S/N) figures of merit that determine whether signal fidelity is sufficiently high to permit peak detection and analysis.
• S/N signal to noise
• the T13 interval the time delay between systolic (P1 ) and iliac peak (P3), is calculated.
• the P2P1 ratio is calculated using the amplitudes of the P2 peak and the systolic peak, in the integrated pulse spectrum.
• the system of the present invention operates passively at a low constant coupling pressure, such as 40 mmHg. After being provided a calibrated blood pressure reading, the device tracks blood pressure by analyzing the timing and amplitudes of the primary left ventricular ejection pulse as well as the arterial pulse reflections, at the middle phalange of the middle finger.
• the system can provide relative, real-time, beat-to-beat pressure measurement values during magnetic resonance imaging.
• the system can include a transimpedance amplifier and transducer, Bluetooth Dongle, USB D/A Converter and Cables, INISO optically isolated input adapter, automatic Blood Pressure Calibration Unit, and runs on a computer using an operating system such as Windows XP, Vista, Windows 7, and sends analog signals back to a BIOPAC MP Device or third-party A/D convertors.
• a BIOPAC Systems, Inc., HLT100C module can be used to interface the INISO Optically Isolated Input Adapter to the BIOPAC Systems, Inc. MP150 data acquisition system to provide optimal isolation for improved subject safety.
• the finger cuff system can be controlled from and stream data to the software running on a PC computer. Communication can be wireless using, for example, the Bluetooth transmission protocol.
• the digital sensor features a miniaturized design based on a piezo-electric sensor, weighs -1 14 grams and runs for about 12-hours on a single battery charge.
• the device tracks pulse reflections that stem from the central arteries, it can be shown to be capable of tracking central blood pressure. Recent experiments furthermore indicate that the technology is particularly suitable as a hemorrhage detector. This is due to the fact that PDA is particularly adept at tracking pulse pressure, which is a sensitive and specific marker for central hypovolemia.
• the device's signal quality is sufficiently high as to enable detailed contour analysis of the radial or digital pulse shape, which is influenced by factors such as systolic and diastolic blood pressure, arterial distensibility and the pressure impedance effects of artery/arteriole interfaces. Specifically, it makes the resolution of the component pulse structure of the radial/digital pulse envelope possible.
• a 35 mm piezo element has about 0.02 uF capacitance and the voltage it produces measuring pulse is nominally about 1 volt. At 1 Hz, 1 volt on the
• the frequency regime of the present invention covers the resting breathing fundamental at the low frequency extreme to the upper frequencies contained in the heartbeat.
• the passband therefore is about 100 mHz to about 60 Hz.
• a transimpedance amplifier converts current input to voltage output.
• the piezo element converts tensile stress in the PZT element to displacement of electrical charge, Q.
• the frequency regime used in the present plethysmograph covers the resting breathing fundamental at the low frequency extreme to the upper frequencies contained in the heartbeat.
• the passband therefore is about 100 milliHz to about 60 Hz.
• the circuit offers a very low impedance to ElectroMagnetic Influence from external sources.
• the high impedance input line offered by the voltage amplifier circuit is, on the other hand, a very good antenna.
• the output current from the piezo element represents the time derivative of the signal, it is always centered at about zero volts and maximum gain can be used to set the system Noise Figure without fear of the signal clipping at the power supply rails.
• the pulsations can be seen on the pressure gage as loading begins.
• the spectral content of the pulsation is of primary concern. That is, in ascultatory (the act of listening for sounds made by internal organs, as the heart and lungs, to aid in the diagnosis of certain disorders), oscillometry (an apparatus for measuring oscillations, especially those of the bloodstream in sphygmometry), all a physician or monitoring party wants to see is a disturbance, in contrast with the structure of the disturbance.
• the present invention is concerned with the structure of the disturbance, that is, the waveform of the disturbance. This is essentially a spectrographic analysis in that it decomposes a pulse wave into its constituent elements, and the constituent elements of the waveform are used to derive data that can be used to support a diagnosis.
• the energy of the pulse stretches the arterial wall like springs. As the pulse moves forward, the walls give back the stored energy to the pulse. There is a continual storage and release of energy to the elastic walls. Ideally, very little energy is lost as the pulse makes its way to the capillaries. The storage and release of energy slows the pulse from about 1500 meters per second as it would be in a steel pipe to around ten meters per second in the artery.

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• 2011
  • 2011-08-11 CN CN2011800483730A patent/CN103220968A/zh active Pending
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