GB2308888A - Blood pressure measuring device - Google Patents
Blood pressure measuring device Download PDFInfo
- Publication number
- GB2308888A GB2308888A GB9626232A GB9626232A GB2308888A GB 2308888 A GB2308888 A GB 2308888A GB 9626232 A GB9626232 A GB 9626232A GB 9626232 A GB9626232 A GB 9626232A GB 2308888 A GB2308888 A GB 2308888A
- Authority
- GB
- United Kingdom
- Prior art keywords
- optic cable
- fibre optic
- pressure
- sphere
- blood
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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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
- A61B5/0215—Measuring pressure in heart or blood vessels by means inserted into the body
- A61B5/02154—Measuring pressure in heart or blood vessels by means inserted into the body by optical transmission
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- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Cardiology (AREA)
- Heart & Thoracic Surgery (AREA)
- Molecular Biology (AREA)
- Physiology (AREA)
- Biophysics (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Vascular Medicine (AREA)
- Medical Informatics (AREA)
- Physics & Mathematics (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
A hollow needle incorporates a fibre optic cable 3 for monitoring blood pressure. Pressure and pressure variations cause compression of the fibre optic cable, the resulting strain causing a modification of the Bragg wavelength of a grating 4 written into the fibre optic cable. Pressure measurement is achieved by monitoring the wavelength of light reflected back from the grating in a measurement system 5 The hollow needle may comprise a catheter 1 or a hypodermic needle. A glass sphere may be incorporated at the end of the fibre optic cable. Deformation of the sphere caused by pressure variations may exert pressure on a grating written in the cable. Alternatively the surface of the sphere may form an interferometer for measuring pressure variations and a grating may be found in the fibre to allow temperature measurements also to be made. The device may be adapted for external use.
Description
PRESSURE MEASURING DEVICE The invention relates to devices for the measurement of pressure, particularly for medical use, for the measurement of a patent's blood pressure, for example.
The conventional method of blood pressure measurement via the use of a stethoscope and cuff has the disadvantage of being operator-dependent.
Current devices for the measurement of pressure in chambers or vessels of the heart are based on manometric or piezoelectric methods. In the first method, inaccuracies occur due to it being essentially an external measurement technique and the second involves the use of electrical signals which ideally should be avoided in the region of the heart.
The present invention seeks to mitigate the above disadvantages of known devices.
According to one aspect of the invention a device for measuring blood pressure in a human or animal body comprises hollow needle means for insertion into a blood vessel and a fibre optic cable located within the hollow needle means wherein the fibre optic cable incorporates pressure sensing means.
According to another aspect of the invention a device for measuring blood pressure in a human or animal body comprises a sensor head for external use incorporating a fibre optic cable wherein the fibre optic cable incorporates pressure sensing means.
One measurement technique employed by the invention depends on the variability of the Bragg wavelength of a grating incorporated within the fibre optic cable. The grating is formed by a variation in the refractive index of the fibre core written when the fibre is drawn. The Bragg wavelength of reflected light from the grating is a function of temperature and strain of the fibre at the site of the grating.
A second measurement technique is an interferometric one.
In a first embodiment of the invention, the pressure sensing means comprises an optical grating which is written into the fibre optic cable. When the fibre is compressed, the
Bragg wavelength of the grating varies, mainly as a result of the refractive index changes in the fibre core. These effects are known; see for example Proceedings Paper No. TU2.2 pp 27-30 "9th Int. Optical Fibre Sensors Conference May 1993" by
J Dakin et al. Measurement of the variations in Bragg wavelength thus provides a measure of the pressure or strain experienced by the fibre optic cable.
In a second embodiment, the pressure sensing means comprises a hollow glass sphere bonded to an end of the fibre optic cable. Pressure on the sphere causes it to reduce its diameter. Deformations of the sphere may then be monitored optically via the fibre optic cable. In one known measurement technique, the sphere surfaces form a low finesse Fabry-Perot interferometer; see, for example Proceedings SPIE Vol 1795 pp 2-5 (Sep 1992) by J Dakin et al. As the mechanical compliance of a hollow sphere is higher than solid body (such as a fibre optic cable) this second embodiment has a greater sensitivity to pressure variation than the first.
It is possible to combine the optical grating and hollow glass sphere embodiments mentioned above by bonding such a sphere to an end of a fibre which includes a grating. It is known that an optical grating can also be used for temperature measurement (see for example our co-pending application GB 9526587.2). Hence by employing Fabry-Perot techniques and monitoring Bragg wavelength this third embodiment can be used to simultaneously monitor blood pressure and temperature (either of the blood or skin surface, depending on whether it is being used intravenously or externally.)
In a fourth embodiment, the pressure sensing means comprises a hollow glass sphere in which is secured a portion of the fibre optic cable, said portion incorporating an optical grating. Pressure on the sphere causes it to reduce its diameter, hence compressing the portion of the cable secured within the sphere.By monitoring the Bragg wavelength using a known technique, see for example Electronics Letters
Vol 32. No. 2 (18 Jan 1996) by J Dakin et al, blood pressure measurements can be made.
Any of the above embodiments may be used externally or intravenously.
The hollow needle means may comprise a hypodermic needle or a catheter or any other suitable type of invasive device.
If a catheter is used, this may take the form of a balloon angioplasty catheter which may have multi-lumens through which the fibre optic cable is fed and, optionally, a guide-wire may be fed.
The hollow needle means may incorporate a radio-opaque material so that its location can be tracked by X-rays.
As a further option, and to avoid the possibility of the fibre optic cable coming into contact with blood, the end of the fibre optic cable adjacent to the hollow needle means tip may be coated with a blood-compatible polymer, eg.
polyurethane.
If desired, the tip of the hollow needle means and/or the hollow glass sphere may also be so-coated.
Advantageously, the present invention measures blood pressure optically requiring no introduction of electrical conductors or electrical potentials or currents into the body, thereby being electrically safe and avoiding electrical interference from external sources.
Other advantages are its small size, compatibility with computer interfacing for data logging, and a sensitivity of 0. lpsi.
The embodiments of the present invention are also suitable for short term (eg. during clinical procedures) and long term monitoring.
Some embodiments of the invention will now be described, by way of example only, with reference to the drawings of which;
Figure 1 is a schematic diagram of a device for measuring blood pressure intravenously using a catheter,
Figure 2 is a schematic diagram of a device for measuring blood pressure externally,
Figure 3 is a schematic diagram of an alternative device for measuring blood pressure intravenously, using a hypodermic needle and
Figure 4 is a schematic diagram of a further alternative device for measuring blood pressure intravenously.
Referring to Figure 1, an invasive device comprises a balloon angioplasty catheter comprising a catheter body 1 and a balloon 2. The catheter body 1 is provided with several lumens, one of which houses a fibre optic cable 3 which incorporates a grating 4. The end of the fibre optic cable which comes into contact with the blood has a polyurethane coating.
The end of the fibre optic cable 3 remote from the catheter body 1 is connected to an optical measurement system 5. The catheter body 1 incorporates a radio-opaque section 6.
In operation, the catheter body 1 is inserted via the skin into a blood vessel. As blood flows past the end of the fibre optic cable 3 the resulting pressure and pressure variations compress the fibre optic cable 3. The fibre optic cable 3 responds to the resulting strain by a modification of the Bragg wavelength of the grating 4 written into the fibre optic cable 3. By monitoring the wavelength of light reflected from the grating 4, the measurement system 5, is able to monitor blood pressure at the tip of the catheter 1.
Referring now to Figure 2, a sensor head 7 incorporates a fibre optic cable 8 whose end remote from the sensor head 14 is connected to an optical measurement system 9. Protruding through the sensor head 7 is a hollow glass sphere 10 which is in contact with the other end of the fibre optic cable 7.
In use, the sphere 10 is held in intimate contact with the patient's skin immediately over a blood vessel. Pressure variations resulting from blood flow cause variations in the diameter of the sphere 10. The sphere is interrogated, optically, via the fibre optic cable 8. As the walls of the sphere 10 act as two reflective surfaces of an interferometer, by monitoring the sphere's reflection spectrum, blood pressure can be measured.
Referring now to Figure 3, a hollow hypodermic needle 11 houses a fibre optic cable 12 which incorporates a grating 13.
One end of the fibre optic cable 12 (adjacent to the needle tip) terminates in a hollow glass sphere 14. The other end of the fibre optic cable 12 is connected to an optical measurement system 15.
In operation, the needle 11 is inserted via the skin into a blood vessel. By monitoring the Bragg wavelength of light reflected from the grating 13, the temperature of the blood at the fibre tip can be determined. By simultaneously monitoring the reflections from the hollow sphere 14, blood pressure can also be determined.
Referring to Figure 4, this embodiment comprises a hollow glass sphere 16 in which is secured a portion of a fibre optic cable 17. The portion of cable inside the sphere 16 incorporates a grating 18 and the end of the fibre cable 17 remote from the sphere 16 is connected to an optical measurement system 19. The sphere 16 and fibre optic cable 17 are located within a hypodermic needle 20. The needle tip and sphere 16 are coated with polyurethane.
In use, with the needle tip inserted into a blood vessel, pressure exerted on the sphere 16 causes it to compress and thereby, compress the portion of cable 17 incorporating the grating 18.
As the mechanical compliance of the sphere 16 is higher than that of a fibre optic cable on its own, the sphere acts as a mechanical amplifier. Pressure sensitivity is therefore enhanced, compared with the first embodiment. Temperature sensitivity is not enhanced however, owing to the similar thermal expansion coefficients of the fibre optic cable 17 and sphere 16. The optical measurement system 19 monitors changes in the Bragg wavelength of the grating 18, thereby providing a measurement of blood pressure.
Claims (14)
1. A device for measuring blood pressure in a human or
animal body comprising hollow needle means for insertion
into a blood vessel and a fibre optic cable located
within the hollow needle means wherein the fibre optic
cable incorporates pressure sensing means.
2. A device as claimed in claim 1 in which the hollow needle
means comprises a hypodermic needle.
3. A device as claimed in claim 1 in which the hollow needle
means comprises a catheter.
4. A device as claimed in any preceding claim in which the
tip of the hollow needle means is coated with
blood-compatible polymer material.
5. A device as claimed in any preceding claim in which the
hollow needle means incorporates a material which is
opaque to X-rays.
6. A device for measuring blood pressure in a human or
animal body comprising a sensor head for external use
incorporating a fibre optic cable wherein the fibre optic
cable incorporates pressure sensing means.
7. A device as claimed in any preceding claim in which the
pressure sensing means comprises an optical grating
written into the fibre optic cable.
8. A device as claimed in any of claims 1 to 6 in which the
pressure sensing means comprises a hollow glass sphere in
which is secured a fibre optic cable incorporating an
optical grating.
9. A device as claimed in either of claims 7 or 8 in which
the optical grating is formed by a variation in the
refractive index of the core of the fibre optic cable.
10. A device as claimed in any of claims 1 to 6 in which the
pressure sensing means comprises a hollow glass sphere
which is bonded to one end of the fibre optic cable.
11. A device as claimed in either of claims 8 or 10 in which
the hollow glass sphere is coated with blood-compatible
polymer material.
12. A device as claimed in any preceding claim in which an
end of the fibre optic cable is coated with
blood-compatible polymer material.
13. A device as claimed in either of claims 4, 11 or 12 in
which said blood-compatible polymer material is
polyurethane.
14. A pressure measuring device substantially as hereinbefore
described with reference to the drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GBGB9526588.0A GB9526588D0 (en) | 1995-12-28 | 1995-12-28 | Pressure measuring device |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9626232D0 GB9626232D0 (en) | 1997-02-05 |
| GB2308888A true GB2308888A (en) | 1997-07-09 |
| GB2308888B GB2308888B (en) | 2000-08-02 |
Family
ID=10786119
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GBGB9526588.0A Pending GB9526588D0 (en) | 1995-12-28 | 1995-12-28 | Pressure measuring device |
| GB9626232A Expired - Fee Related GB2308888B (en) | 1995-12-28 | 1996-12-18 | Pressure measuring device |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GBGB9526588.0A Pending GB9526588D0 (en) | 1995-12-28 | 1995-12-28 | Pressure measuring device |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB9526588D0 (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2371359A (en) * | 2000-09-07 | 2002-07-24 | Optomed As | Fibre optic sensors for invasive medical use |
| GB2371360A (en) * | 2000-09-07 | 2002-07-24 | Optomed As | Multiple parameter fiber optic probe |
| GB2389902A (en) * | 2002-06-21 | 2003-12-24 | Qinetiq Ltd | Fibre optic temperature and flow rate sensing |
| WO2005057192A1 (en) * | 2003-12-08 | 2005-06-23 | Sentronic GmbH Gesellschaft für optische Meßsysteme | Sensitive system for detecting chemical and/or physical state changes inside packaged media |
| WO2012164481A1 (en) | 2011-06-01 | 2012-12-06 | Koninklijke Philips Electronics N.V. | System for distributed blood flow measurement |
| EP2865326A1 (en) * | 2013-10-25 | 2015-04-29 | Sinvent AS | In-vivo pressure monitoring system |
| WO2015059969A1 (en) * | 2013-10-25 | 2015-04-30 | ニューブレクス株式会社 | Fiber optic biodiagnostic sensor system and vascular insertion type device for measuring pressure distribution |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4599901A (en) * | 1982-09-30 | 1986-07-15 | University Of California | Pressure-sensitive optrode |
| US4691709A (en) * | 1986-07-01 | 1987-09-08 | Cordis Corporation | Apparatus for measuring velocity of blood flow in a blood vessel |
| WO1988000023A1 (en) * | 1986-06-25 | 1988-01-14 | Radisensor Ab | Miniaturized sensor for physiological pressure measurements |
| US4873989A (en) * | 1984-03-08 | 1989-10-17 | Optical Technologies, Inc. | Fluid flow sensing apparatus for in vivo and industrial applications employing novel optical fiber pressure sensors |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5154680A (en) * | 1990-03-27 | 1992-10-13 | Rutgers University | Pressure waveform monitor |
| US5280786A (en) * | 1992-01-21 | 1994-01-25 | Fiberoptic Sensor Technologies, Inc. | Fiberoptic blood pressure and oxygenation sensor |
-
1995
- 1995-12-28 GB GBGB9526588.0A patent/GB9526588D0/en active Pending
-
1996
- 1996-12-18 GB GB9626232A patent/GB2308888B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4599901A (en) * | 1982-09-30 | 1986-07-15 | University Of California | Pressure-sensitive optrode |
| US4873989A (en) * | 1984-03-08 | 1989-10-17 | Optical Technologies, Inc. | Fluid flow sensing apparatus for in vivo and industrial applications employing novel optical fiber pressure sensors |
| WO1988000023A1 (en) * | 1986-06-25 | 1988-01-14 | Radisensor Ab | Miniaturized sensor for physiological pressure measurements |
| US4691709A (en) * | 1986-07-01 | 1987-09-08 | Cordis Corporation | Apparatus for measuring velocity of blood flow in a blood vessel |
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7003184B2 (en) | 2000-09-07 | 2006-02-21 | Optomed. As | Fiber optic probes |
| GB2371360A (en) * | 2000-09-07 | 2002-07-24 | Optomed As | Multiple parameter fiber optic probe |
| GB2371359A (en) * | 2000-09-07 | 2002-07-24 | Optomed As | Fibre optic sensors for invasive medical use |
| GB2371359B (en) * | 2000-09-07 | 2005-02-02 | Optomed As | Fiber optic probes |
| GB2371360B (en) * | 2000-09-07 | 2005-02-16 | Optomed As | Multi-parameter fiber optic probes |
| US7050172B2 (en) | 2002-06-21 | 2006-05-23 | Qinetiq Limited | Optical sensing apparatus |
| GB2389902B (en) * | 2002-06-21 | 2005-06-22 | Qinetiq Ltd | Optical sensing apparatus |
| GB2389902A (en) * | 2002-06-21 | 2003-12-24 | Qinetiq Ltd | Fibre optic temperature and flow rate sensing |
| WO2005057192A1 (en) * | 2003-12-08 | 2005-06-23 | Sentronic GmbH Gesellschaft für optische Meßsysteme | Sensitive system for detecting chemical and/or physical state changes inside packaged media |
| WO2012164481A1 (en) | 2011-06-01 | 2012-12-06 | Koninklijke Philips Electronics N.V. | System for distributed blood flow measurement |
| US11553852B2 (en) | 2011-06-01 | 2023-01-17 | Koninklijke Philips N.V. | System for distributed blood flow measurement |
| EP2865326A1 (en) * | 2013-10-25 | 2015-04-29 | Sinvent AS | In-vivo pressure monitoring system |
| WO2015059217A1 (en) * | 2013-10-25 | 2015-04-30 | Sinvent As | In-vivo pressure monitoring system |
| WO2015059969A1 (en) * | 2013-10-25 | 2015-04-30 | ニューブレクス株式会社 | Fiber optic biodiagnostic sensor system and vascular insertion type device for measuring pressure distribution |
| JPWO2015059969A1 (en) * | 2013-10-25 | 2017-03-09 | ニューブレクス株式会社 | Optical fiber type biomedical sensor system and blood vessel insertion type distributed pressure measuring device |
| US10028667B2 (en) | 2013-10-25 | 2018-07-24 | Neubrex Co., Ltd. | Fiber optic in vivo diagnostic sensor system and blood vessel insertable pressure distribution measurement device |
| US11298038B2 (en) | 2013-10-25 | 2022-04-12 | Sintef Tto As. | In-vivo pressure monitoring system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9626232D0 (en) | 1997-02-05 |
| GB2308888B (en) | 2000-08-02 |
| GB9526588D0 (en) | 1996-02-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20051218 |