Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
2001-10-02
2003-10-07
Winakur, Eric F. (Department: 3736)
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
Reexamination Certificate
active
06631282
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to determining analyte concentrations within living tissue. More particularly, this invention relates to a device for isolating regions of living tissue for consistent transfer of thermal spectra to and from the tissue.
2. Description of the Related Art
Millions of diabetics are forced to draw blood on a daily basis to determine their blood glucose levels. A search for a non-invasive methodology to accurately determine blood glucose levels has been substantially expanded in order to alleviate the discomfort of these individuals. A significant advance in the state of the art of non-invasive blood glucose analysis has been realized by an apparatus taught in U.S. Pat. No. 6,198,949, titled SOLID-STATE NON-INVASIVE INFRARED ABSORPTION SPECTROMETER FOR THE GENERATION AND CAPTURE OF THERMAL GRADIENT SPECTRA FROM LIVING TISSUE, issued Mar. 6, 2001, and by methodology taught in U.S. Pat. No. 6,161,028, titled METHOD FOR DETERMINING ANALYTE CONCENTRATION USING PERIODIC TEMPERATURE MODULATION AND PHASE DETECTION, issued Dec. 12, 2000, both of which are hereby incorporated in their entirety by reference.
U.S. Pat. No. 6,198,949 discloses a spectrometer for non-invasive transfer of thermal gradient spectra to and from living tissue. The spectrometer includes an infrared transmissive thermal mass, referred to as a thermal mass window, for inducing a transient temperature gradient in the tissue by means of conductive heat transfer with the tissue, and a cooling system in operative combination with the thermal mass for the cooling thereof. Also provided is an infrared sensor for detecting infrared emissions from the tissue as the transient temperature gradient progresses into the tissue, and for providing output signals proportional to the detected infrared emissions. A data capture system is provided for sampling the output signals received from the infrared sensor as the transient temperature gradient progresses into to the tissue. The transient thermal gradients arising due to the intermittent heating and cooling of the patient's skin generate thermal spectra which yield very good measurements of the patient's blood glucose levels.
Although the apparatus taught in the above-mentioned U.S. Pat. No. 6,198,949 has led to a significant advance in the state of the art of non-invasive blood glucose analysis, one possible source of error arises due to the nature of the contact between the thermal mass window and the patient's skin. If several separate measurements are required, it follows that the thermal mass window must be brought into contact with the patient's skin several times. The problem with this is that each of such contacts tends to be slightly different. For instance, slight differences in skin topology and/or pressure may arise at the interface between the thermal mass window and the skin; the patient may move that portion of his or her body, for instance the arm, which is in contact with the thermal mass window; and muscular tension may change between measurements. Each of these factors, and perhaps others as well, tend to complicate the already complex nature of the contact between the skin and the thermal mass window.
SUMMARY OF THE INVENTION
A device and method are provided for use with a non-invasive optical measurement system, such as but not limited to a thermal gradient spectrometer for improved determination of analyte concentrations within living tissue. In a preferred embodiment, a site selector is secured to a patient's forearm thereby isolating a measurement site on the patient's skin for determination of blood glucose levels. The site selector attaches to or engages a window of the gradient spectrometer and thus forms an interface between the patient's skin and the window. When the spectrometer must be temporarily removed from contact with the patient's skin, such as to allow the patient mobility, the site selector is left secured to the forearm so as to maintain a consistent measurement site on the skin. When the spectrometer is later reattached to the patient, the site selector will again form an interface between the spectrometer and the same location of skin as before.
In one embodiment, a device for use with a non-invasive optical measurement system comprises a generally flat member having an aperture passing from a first surface of the flat member to a second surface of the flat member. The flat member is preferably made of injection-molded plastic, and may be configured to minimize the formation of condensation thereon. The aperture has a predetermined cross-sectional shape and allows substantially unimpeded transmission of thermal spectra to and from skin of a patient through the flat member. The first surface comprises a contact surface which presses against the skin of the patient when the flat member is attached thereto. The second surface comprises an interface surface which is shaped to receive the non-invasive optical measurement system.
A fastening strap may be connected to the flat member and adapted to attach the flat member to a predetermined location on the patient, such as a forearm. The fastening strap comprises a fixed end and an adjustable end. The fixed end passes through a first of opening within the flat member and the adjustable end passes through a second of opening within the flat member such that the fastening strap assumes an annular configuration having an interior surface and an exterior surface. The fixed end is folded back and affixed to the interior surface of the fastening strap, and the adjustable end is folded over and removably attached to the exterior surface of the fastening strap with a fastener such as a buckle or Velcro™.
In another embodiment, the contact surface of the flat member includes adhesive material which is adapted to attach the flat member to the predetermined location on the patient. With this embodiment, the contact surface includes a pressure sensitive adhesive surface which enables attaching the site selector to the patient's skin without using the above-mentioned fastening strap.
In operation the flat member and the aperture cooperate to grip the skin of the patient when pressed against the skin under force applied by the fastening strap. Furthermore, the flat member is coupled with the non-invasive optical measurement system such that removal of the measurement system from the flat member leaves the predetermined location on the patient substantially unaltered.
One aspect of the invention provides a device for maintaining a predetermined location on the skin of a patient to facilitate use of a noninvasive optical measurement system. The device comprises a generally flat member having an aperture passing from a first surface of the flat member to a second surface of the flat member. Preferably, the flat member is made of a rigid material, such as injection-molded plastic. The aperture is adapted to allow substantially unimpeded transmission of thermal spectra to and from skin of a patient through the flat member. The first surface comprises a contact surface which presses against the skin of the patient when the flat member is attached thereto. The second surface comprises an interface surface which is shaped to receive the noninvasive optical measurement system. The interface surface preferably comprises at least one raised section which facilitates orienting the noninvasive optical measurement system relative to the flat member such that the noninvasive optical measurement system assumes angular and axial alignment with the aperture. The aperture preferably comprises at least one protrusion which facilitates attaching the noninvasive optical measurement system to the flat member such that the interface surface receives the noninvasive optical measurement system. The flat member and the aperture cooperate to grip the skin of the patient when applied to the skin.
A fastening strap is connected to the flat member and is adapted to attach the flat member to the predetermined loca
Agostino Mark D.
Braig James R.
Cortella Julian
Goldberger Daniel S.
Rule Peter
Knobbe Martens Olson & Bear
OptiScan Biomedical Corporation
Winakur Eric F.
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