GB2427691A - Apparatus to detect patent foramen ovale - Google Patents
Apparatus to detect patent foramen ovale Download PDFInfo
- Publication number
- GB2427691A GB2427691A GB0512908A GB0512908A GB2427691A GB 2427691 A GB2427691 A GB 2427691A GB 0512908 A GB0512908 A GB 0512908A GB 0512908 A GB0512908 A GB 0512908A GB 2427691 A GB2427691 A GB 2427691A
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- GB
- United Kingdom
- Prior art keywords
- person
- pressure transducer
- pulse oximeter
- conditioning circuit
- housing
- 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.)
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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
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/1455—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters
- A61B5/14551—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters for measuring blood gases
-
- 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
- A61B5/0205—Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
-
- 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
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- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Cardiology (AREA)
- Physics & Mathematics (AREA)
- Physiology (AREA)
- Heart & Thoracic Surgery (AREA)
- Veterinary Medicine (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Biophysics (AREA)
- Medical Informatics (AREA)
- Molecular Biology (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Pulmonology (AREA)
- Vascular Medicine (AREA)
- Ophthalmology & Optometry (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Optics & Photonics (AREA)
- Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
Abstract
An apparatus 2 to detect patent foramen ovale (the presence of an opening between the right atrium and left atrium of the heart) uses a pressure transducer 6 and a pulse oximeter 16 to detect a drop in blood oxygenation after a Valsalva manoeuvre is performed. The apparatus 2 comprises a pressure transducer 6, a pressure transducer conditioning circuit 8, a pulse oximeter probe 16, and a pulse oximeter conditioning circuit 10. The pressure transducer 6, pressure transducer conditioning circuit 8 and pulse oximeter conditioning circuit 10 are contained in a housing 12, and the pulse oximeter probe 16 extends from the housing 2. The housing 12 is hand held during use of the apparatus. An output 18 is connected to an electronic display 22, 24, which may display measured pressure and oxygenation. The pulse oximeter 16 may be clipped to the user's ear 38, and the housing 12 may include a mouthpiece 32 into which the user 4 blows during use of the apparatus 2.
Description
APPARATUS FOR DETECTING
PATENT FORAMEN OVALE IN A PERSON
This invention relates to apparatus to detecting patent foramen ovale in a person.
In an unborn child, there is an opening between the right atrium and the left atrium of the heart. This opening allows blood to circulate without passing through the lungs of the unborn child. After birth, the opening closes to allow blood to circulate through the lungs of the child. In many people, the opening fails to close completely, and there exists a potential shunt between the right and left atrium chambers. This condition is called patent foramen ovale.
Patent foramen ovale may be diagnosed with a contrast transoesophageal echocardiogram. The diagnosis is performed in a hospital. The hospital procedure allows a cardiologist to view the internal structures of the heart, and the major vessels of the heart by inserting a probe down the oesophagus. The probe contains an ultrasonic transmitter and a receiver. The transmitted ultrasound provides echoes of structures in the heart. These echoes are picked up by the receiver, and they are used to create an image of the heart that is displayed on a video monitor.
Before the contrast transoesophageal echocardiogram is performed, a liquid anaesthetic is given to the patient to gargle. This numbs the patient's throat and tongue, and makes the probe easier to swallow. The patient is instructed to take several deep breaths in order to help relax the muscles in the back the patient's throat, so that the probe can be swallowed more easily. During the test, the patient is sedated, and an intravenous contrast medium is administered in order to improve the definition of the image. The procedure may last from 60 -90 minutes.
In a person with patent foramen ovale, the opening may be closed using cardiac catherisation. This involves making a small incision in the person's groin, this being done under intravenous sedation. A guidewire and delivery sheath are then introduced into the person's vein and passed into their heart, across the patent foramen ovale. A closure device is inserted through the opening through the delivery sheath and it is then released, thereby closing the patent foramen ovale.
Although estimates vary, one major study detected patent foramen ovale in 26% of the population, the majority of whom live with the condition without being aware of any adverse effects. Patent foramen ovale has been linked with some medial conditions such for example as lschaemic stroke.
However, the rarity of such conditions, and the weakness of the link with patent foramen ovale has meant that widespread screening for patent foramen ovale has not been required.
Recent evidence has come to light that suggests that there is a strong link between patent foramen ovale and a type of severe migraine that affects vision and that is known as migraine with aura. Studies to confirm this link are currently being carried out. If a strong link between patent foramen ovale and the migraine is established, then apparatus capable of large scale screening will be required because the availability of current detection methods will be inadequate to cope with the demand.
In 1957 Lee and Gimlette described a technique for the detection of patent foramen ovale, British Medical Journal 1278 June 1, 1957, A Simple Test For Interatrjal Communication. In this technique, a Valsalva manoeuvre was performed whilst the person's arterial oxygenation was monitored using a pulse oximeter probe attached to the person's earlobe.
The Valsalva manoeuvre is performed by getting the person forcibly to exhale, whilst the person keeps their mouth and nose closed and thus generates an increase in pressure in the thorax.
In the 1957 technique of Lee and Gimlette, a diagnosis of patent foramen ovale is confirmed if there is a temporary reduction of oxygenation after the Valsalva manoeuvre. During the Valsalva manoeuvre, the increased pressure in the person's chest cavity forces deoxygenated blood in the right atrium through the opening in the atrium wall to mix with oxygenated blood in the left atrium. This reduces the overall level of oxygenation of blood in the left atrium. This partially deoxygenated blood is then pumped to the person's head, causing a reduction in the pulse oximeter measurement at the earlobe. In order for Lee and Gimlette to perform their technique, they measured the pressure at the person's mouth during the Valsalva manoeuvre using a mercury sphygmomanometer. The mercury sphygmomanometer is a device designed to measure blood pressure and it normally comprises an inflatable arm cuff. The mercury sphygmomanometer had to be modified to replace the inflatable arm cuff with a mouthpiece.
The apparatus used by Lee and Gimlette to perform their technique was basically modified pieces of existing equipment. The resulting apparatus was sufficient to prove the validity of the Lee and Gimlette technique but is was not able to be produced on a commercial basis.
It is an aim of the present invention to produce apparatus which is able to carry out the Lee and Gimlette technique in order to detect for the patent foramen ovale, and which is also capable of commercial production.
Accordingly, in one non-limiting embodiment of the present invention there is provided apparatus for detecting patent foramen ovale in a person, which apparatus comprises a pressure transducer; a pressure transducer conditioning circuit; a pulse oximeter conditioning circuit; a housing which is held in the person's hand during use of the apparatus and which contains the pressure transducer, the pressure transducer conditioning circuit and the pulse oximeter conditioning circuit; a pulse oximeter probe which extends from the housing and which is for connection to the person; and output means for connection to electronic display means for displaying data indicating if the person has the patent foramen ovale.
The apparatus of the present invention is compact and thus convenient to use. The displayed data may be simply read from the electronic display means. The display data may be seen as a dip in oxygenation occurring after a Valsalva manoeuvre on the person.
The pressure transducer may be a silicon piezo-resistive pressure transducer. Other pressure transducers may be employed.
The pressure transducer conditioning circuit may be any suitable and appropriate conditioning circuit. The pressure transducer conditioning circuit may comprise amplifier means and an analogue-to-digital converter.
The pulse oximeter conditioning circuit may be any suitable and appropriate conditioning circuit. The pulse oximeter circuit may comprise an analogue-to-digital converter.
Preferably, the output means is for plug-in connection to the electronic display means. Other types of connection may be employed.
Preferably, the output means comprises a cable, and connector means for plugging into a universal serial bus part of the electronic display means.
The apparatus of the present invention may include the electronic display means. The electronic display means will usually be a computer having a display panel.
The apparatus of the present invention may include a mouthpiece which extends from the housing and into which the person blows during use of the apparatus.
Preferably, the mouthpiece is a removable mouthpiece which is removable from the housing, and which is disposable after it has been used by the person. With the mouthpiece being disposable, the apparatus of the present invention can easily be reused by many people, simply by providing new mouthpieces for each new person.
The pulse oximeter probe may comprise a cable extending from the housing, and a clip for clipping to a body part of the person.
Preferably, the clip is constructed for clipping to an ear of the person.
The clip may however be constructed for clipping to another part of the person, for example to their finger. The pulse oximeter probe may be such that in the probe there are first and second light emitting diodes that radiate red and infrared light respectively in a direction going through a body part of the person, for example the person's earlobe. Also in the probe, a photodiode that produces an output current proportional to the amount of incident light received through the patient's body part. The red and the infrared light emitting diodes are switched on alternately, and the relative amount of red and infrared light received by the photodiode is determined by the oxygenation of the blood. The first and second light emitting diodes may be one half of the probe, and the photodiode may be in the other half of the probe.
The display means may additionally provide instructions for the person on what the person is to do in order to assist in the use of the apparatus. The instructions may be audio instructions and/or visual instructions.
An embodiment of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 shows apparatus in use for detecting patent foramen ovale in a person; and Figure 2 shows in more detail parts of the apparatus shown in Figure 1.
Referring to Figure 1, there is shown apparatus 2 for detecting patent foramen ovale in a person 3. The apparatus 2 comprises a pressure transducer 6, a pressure transducer conditioning circuit 8, and a pulse oximeter conditioning circuit 10. A housing 12 is held in the person's hand 14 during use of the apparatus 2. The housing 12 contains the pressure transducer 6, the pressure transducer conditioning circuit 8, and the pulse oximeter conditioning circuit 10.
The apparatus 2 also comprises a pulse oximeter probe 16 which extends from the housing 12 and which is for connection to the person 4.
Output means 18 are provided for connection to electronic display means 20. The electronic display means 20 is for displaying data as a display 22 on a screen 24. The display 22 indicates if the patient has the patent foramen ovale. As can be seen, the display 22 is such that a dip 23 in oxygenation identified by Sp02 has occurred after a Valsalva manoeuvre has been performed.
The output means 18 is for plug-in connection to the electronic display means 20. More specifically, the output means 18 comprises a cable 26 and connector means 28 for plugging into a universal serial bus (USB) port 30 of the electronic display means 20.
The apparatus 2 includes a mouthpiece 32 which extends from the housing 12 and into which the person 4 blows during use of the apparatus 2.
The mouthpiece 32 is a removable mouthpiece which is removable from the housing 12 and which is disposable after it has been used by the person.
With the use of such a disposable mouthpiece 32, the apparatus 2 can easily and hygienically be used for many different persons.
The pulse oximeter probe 16 comprises a cable 34 which extends from the housing 12, and a clip 36 for clipping to the person's ear 38.
As can be seen from Figure 1, the apparatus 2 is compact and very convenient to use. The apparatus 2 enables the person 4 easily, quickly and non-invasively to be tested for patent foramen ovale.
Referring now to Figure 2, there is shown in more detail the components of the pressure transducer conditioning circuit 8, the pulse oximeter conditioning circuit 10 and the electronic display means 20. More specifically, as shown in Figure 2, the pressure transducer 6 is a silicon piezo-resistive pressure transducer 6 which consists of four elements 40 whose resistance changes under the influence of an applied pressure. The elements 40 are configured in a Wheatstone bridge arrangement with a differential output. The pressure transducer 6 is a compact, low power pressure transducer 6 having a good long term stability. The pressure transducer 6 is supplied with a regulated power supply along lines 42, 44.
The differential output from the pressure transducer 6 passes along lines 46, 48 to an instrumentation amplifier 50. The instrumentation amplifier 50 amplifies the differential output. The output from the instrumentation amplifier 50 passes along line 52 to an analogue-to-digital converter 54.
The output from the analogue-to-digital converter 54 passes along line 56 to a microprocessor circuit 58 in the electronic display means 20. The microprocessor circuit 58 reads the output from the analogue-to-digital converter 54 and multiplies the signal by a calibration factor to obtain a pressure reading.
The pulse oximeter conditioning circuit 10 receives signals from the pulse oximeter probe 16. As shown in Figure 2, the pulse oximeter probe 16 is such that in one half of the probe there are two light emitting diodes 60, 62 that radiate red and infrared light respectively in a direction going through the lobe of the person's ear 38. In the other half of the probe is a photodiode 64 that produces an output current proportional to the amount of incident light received through the earlobe. The red and infrared light emitting diodes, 60, 62 are switched on alternately. The output of the photodiode 64 is switched in synchrony with the light emitting diodes 60, 62 in order to obtain the red and infrared signals. The outputs from the photodiode 64 are converted to a digital format using an analogue-to-digital converter 66. The output of the analogue-to-digital converter 66 passes along line 68 where it is read by the microprocessor circuit 58. The microprocessor circuit 58 determines the relative amplitude of the red and infrared signal strength and uses an internal look-up table to find the corresponding amount of oxygenation. The output from the microprocessor circuit 58 passes in the form of Sp02 and pressure signals along line 70 to the display 22.
It is to be appreciated that the embodiment of the invention described above with reference to the accompanying drawings has been given by way of example only and that modifications may be effected. Thus, for example, the electronic display means 20 in the form of the computer may give an electronic display which includes instructions for the person 4 on what to do in order to assist in the use of the apparatus 2. If such instructions are employed, then the instructions may be audio instructions and/or visual instructions.
Claims (15)
1. Apparatus for detecting patent foramen ovale in a person, which apparatus comprises a pressure transducer; a pressure transducer conditioning circuit; a pulse oximeter conditioning circuit; a housing which is held in the person's hand during use of the apparatus and which contains the pressure transducer, the pressure transducer conditioning circuit and the pulse oximeter conditioning circuit; a pulse oximeter probe which extends from the housing and which is for connection to the person; and output means for connection to electronic display means for displaying data * *.
indicating if the person has the patent foramen ovale. *S.. * **
2. Apparatus according to claim I in which the pressure transducer is a S. .
silicon piezo-resistive pressure transducer.
S..... * S S. 5 * . S S.
3. Apparatus according to claim I or claim 2 in which the pressure transducer conditioning circuit comprises amplifier means and an analogueto-digital converter.
4. Apparatus according to any one of the preceding claims in which the pulse oximeter conditioning circuit comprises an analogue-to-digital converter.
5. Apparatus according to any one of the preceding claims in which the output means is for plug-in connection to the electronic display means.
6. Apparatus according to claim 5 in which the output means comprises a cable and connector means for plugging into a universal serial bus part of the electronic display means.
7. Apparatus according to any one of the preceding claims and including the electronic display means. * S. * S S *I*S
8. Apparatus according to claim 7 in which the electronic display means : *** is a computer having a display panel. S. 55
S I..
S
9. Apparatus according to any one of the preceding claims and including a mouthpiece which extends from the housing and into which the person blows during use of the apparatus.
10. Apparatus according to claim 9 in which the mouthpiece is a removable mouthpiece which is removable from the housing, and which is disposable after it has been used by the person.
11. Apparatus according to any one of the preceding claims in which the pulse oximeter probe comprises a cable which extends from the housing, and a clip for clipping to a body part of the person.
12. Apparatus according to claim 11 in which the clip is constructed for clipping to an ear of the person.
13. Apparatus according to any one of the preceding claims in which the display means additionally provides instructions for the person on what the person is to do in order to assist in the use of the apparatus.
14. Apparatus according to claim 13 in which the instructions are audio instructions and/or visual instructions. * ** * * S S... I...
15. Apparatus for detecting patent foramen ovale in a person, ::::. substantially as herein described with reference to the accompanying
S S..
drawings.
*SSS*S * S S. S
S S I
IS
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0512908A GB2427691A (en) | 2005-06-24 | 2005-06-24 | Apparatus to detect patent foramen ovale |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0512908A GB2427691A (en) | 2005-06-24 | 2005-06-24 | Apparatus to detect patent foramen ovale |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0512908D0 GB0512908D0 (en) | 2005-08-03 |
| GB2427691A true GB2427691A (en) | 2007-01-03 |
Family
ID=34856094
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0512908A Withdrawn GB2427691A (en) | 2005-06-24 | 2005-06-24 | Apparatus to detect patent foramen ovale |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2427691A (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0204394A1 (en) * | 1985-06-03 | 1986-12-10 | McIntyre, Kevin M. | Apparatus for evaluating heart mechanical performance |
| WO2000021434A1 (en) * | 1998-10-15 | 2000-04-20 | Qrs Diagnostic, Llc | Personal computer card for collection of real-time biological data |
| US6083156A (en) * | 1998-11-16 | 2000-07-04 | Ronald S. Lisiecki | Portable integrated physiological monitoring system |
| EP1229826A2 (en) * | 1999-10-22 | 2002-08-14 | Respironics, Inc. | Method and apparatus for determining cardiac output |
| EP1349495A1 (en) * | 2000-08-25 | 2003-10-08 | Harry Louis Platt | System for physiological monitoring during sleep |
-
2005
- 2005-06-24 GB GB0512908A patent/GB2427691A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0204394A1 (en) * | 1985-06-03 | 1986-12-10 | McIntyre, Kevin M. | Apparatus for evaluating heart mechanical performance |
| WO2000021434A1 (en) * | 1998-10-15 | 2000-04-20 | Qrs Diagnostic, Llc | Personal computer card for collection of real-time biological data |
| US6083156A (en) * | 1998-11-16 | 2000-07-04 | Ronald S. Lisiecki | Portable integrated physiological monitoring system |
| EP1229826A2 (en) * | 1999-10-22 | 2002-08-14 | Respironics, Inc. | Method and apparatus for determining cardiac output |
| EP1349495A1 (en) * | 2000-08-25 | 2003-10-08 | Harry Louis Platt | System for physiological monitoring during sleep |
Non-Patent Citations (1)
| Title |
|---|
| British Medical Journal, June 1957, G J Lee & T M D Gimlette, "A simple test for interatrial communication", pages 1278-1281. * |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0512908D0 (en) | 2005-08-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |