Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Patent
1997-05-14
1998-10-20
Jaworski, Francis
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
600529, A61B 800
Patent
active
058239650
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a device for examination and measurement of constrictions or passages in cavities by means of acoustic reflectometry, the device comprising an electric signal source, a hose with a distal end to be introduced through an entrance to a cavity, a first transducer for transfer of an activation signal from the signal source to and through the hose, a second transducer for reception of response signals from the hose, the first and second transducers being connected with the hose close to its proximal end, and a computer adapted for analysis of the response signals in relation to the activation signal.
2. Background Art
For examination and measurement of blockings, deformations, movements etc. in various human and animal cavities, e.g. pharynx, larynx and other air and alimentary passages, arteries etc. various methods are known.
In catheter examinations, balloon-angioplasty etc. it is known to use a probe in the shape of a hose of flexible material.
Another method is based on measurement of reflection (reflectometry) using an acoustic, transient excitation signal which, through a hose and through the patient's mouth, is sent into the air passages of the patient, cf. e.g. U.S. Pat. No. 4,326,416.
Another method based on the use of a non-transient excitation signal--random or pseudorandom signal--is used in an equipment manufactured by the applicant firm, under the commercial designation SRE 2000 and SRE 2000 PC.
Especially in connection with examination of movements in the air passages and examination of stertorous respiration mainly pressure transducers, placed in or on catheters to be introduced in nose or mouth, have so far been used. This allows for measurement of pressure variations, constrictions, etc. in nose and throat.
A drawback in this technique is to be seen in that the measurement probe must include a relatively large number of closely located pressure transducers connected to a corresponding apparatus which offers the possibility, on a screen with a sufficient resolution, to determine the position of and pressure at each examined spot.
Known techniques also include endoscopy by which optical examinations are made of nose, pharynx and other internal organs. However, these examinations have a certain number of limitations, including the clarity and size of the optical image, the size of the catheter and especially the lack of catheter flexibility which makes, the catheter unsuitable for examination of, e.g., stertorous respiration.
CT and MRI scannings have been tried, but involve long periods of measurement which do not give useful measurements and no dynamic measurements at all.
By using acoustic reflectometry of the above mentioned kind, it is known that it is possible to measure across-sectional areas in the air passages as a function of the distance from the transducer used for emission of the excitation signal, cf. the above patent U.S. Pat. No. 4,326,416 or an article: "Airway geometry by analysis of acoustic pulse response measurements" by Andrew C. Jackson et al. in J. Appl. Physiology, 43(3): 525-536, 1977.
Direct measurement limits measurements of cross modes, i.e. cross resonance, and of the adjacent cavities, which, to a large extent, limits the use of such direct measurements having large differences in the cross-sectional areas as a function of the distance from the signal source.
Especially when examining stertorous respiration, the use of direct measurements is hampered by the transient or continuous sound influence, necessary for the measurements, which affects the sleep state or awakens the patient during the examination phase itself, and also causes measurement errors because of noise from the measurement microphone and a measurement error due to the very large cavity made up by the mouth and throat.
SUMMARY OF THE INVENTION
The invention aims at remedying the above mentioned disadvantages and in order to do so a device of the type mentioned in the introduction is according to the invention c
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patent: 5333614 (1994-08-01), Feiring
patent: 5445144 (1995-08-01), Wodicka et al.
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Jaworski Francis
RhinoMetrics A/S
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