Surgery – Diagnostic testing – Measuring anatomical characteristic or force applied to or...
Patent
1998-10-07
2000-07-04
O'Connor, Cary
Surgery
Diagnostic testing
Measuring anatomical characteristic or force applied to or...
33511, 604264, 73715, A61B 5103
Patent
active
060831790
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a sensor to detect changes in the cross section of an elongated body cavity.
BACKGROUND AND PRIOR ART
In medical contexts, there are needs for a sensor (catheter) which is suitable for insertion in elongate and generally duct-like body cavities of varying cross-section, e.g. in the urinary tract in order to indicate changes in the cross-section of the cavity. In such duct-like cavities, the tissue pressure may, e.g. through muscular action, vary considerably between different regions of the cavity. There is, therefore, a need to be able, in addition to generally indicating changes in the cross-section of the cavity, also to be able to indicate locally occurring changes in the cross-section.
Patent specification U.S. Pat. No. 4,711,249 discloses a tubular sensor disposed to be inserted in an elongate cavity and detect changes in the dimensions of the cavity. The sensor consists of a number of sequentially disposed and spaced apart rigid tube sections in whose ends are inserted mechanically rigid bodies which sealingly connect to the surrounding tube sections. Between the ends of the tube sections, there are formed circumferentially extending grooves which are covered by elastic membranes or diaphragms. Between the membranes and the rigid bodies, spaces are formed.
Each one of the rigid bodies has a central chamber which, through an aperture, is connected to the space between the rigid body and the membrane. In its one end, the chamber has a mechanically rigid closure and in its other end a flexible closure. The space between the membrane and the rigid body as well as the chamber in the body is filled with liquid. Pressure changes in the chamber of the body are registered by a sensor abutting against the flexible closure.
The apparatus disclosed in U.S. Pat. No. 4,711,249 suffers from the drawback that only in those parts of the cylindrical sensor where the elastic membranes bridge the space which is formed between the ends of the tubular portions can the sensor register a change of the circumference of a surrounding organ. This implies that only short portions of the cylindrical sensor are capable of registering changes in the circumference of the surrounding organ. In regions which are located between the membranes, no detection of changes in the circumference of the surrounding organ takes place, in addition to which the sensor prevents the surrounding organ from assuming a circumference which is less than the circumference of the sensor.
SUMMARY OF THE INVENTION
The present invention relates to an apparatus provided with a tubular portion along which a change in the size and/or configuration of the circumference of a surrounding organ is detected regardless of where such change takes place along the cylindrical portion. This is attained by means of an apparatus comprising a catheter-like body whose internal cavity varies in response to external pressure.
BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS
The present invention will now be described in greater detail with reference to a number of figures, in which:
FIG. 1 is an overall view of an apparatus seen from the side;
FIG. 1a is the section a--a in FIG. 1 on a magnified scale;
FIG. 2 is a cross-section through one embodiment of an apparatus in which this includes a Hall element for co-operation with an elastic membrane or diaphragm;
FIG. 3 is a cross-section corresponding to that of FIG. 2 where the membrane has been moved downwards in the figure;
FIGS. 4a-c are cross-sections through various embodiments of the membranes;
FIG. 5 is a cross-section through one embodiment of the apparatus in which this includes an electrically conductive elastic membrane;
FIG. 6 is a cross-section corresponding to that of FIG. 4 in which the membrane has been moved downwards in the figure; and
FIGS. 7a-e show embodiments of a substantially cylindrical sensor portion included in the apparatus.
DETAILED DESCRIPTION
FIGS. 1 and 1a show an apparatus 1 which includes a substantially cylindrical portion 10
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Formo Medical AB (Publ.)
Marmor II Charles
O'Connor Cary
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