Abstract:
A strap or fastener for removably securing an oximeter probe to the appendage of a patient. The strap is made of an elastic material that wraps around the outside of the oximeter probe and is secured to the oximeter probe by attachment mechanisms such as Velcro that can be readjusted after initial application without producing excessive stress on the spring hinge of the oximeter probe.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to medical sensors for detecting physiological functions and, in particular, to an apparatus for securing an oximeter probe to an appendage of a patient. 
     Pulse oximetry is a non-invasive medical technique useful for measuring certain vascular conditions. A pulse oximetry system comprises a sensor appliance containing a light source, such as an L.E.D., and a light sensor, such as a photodetector, and is mounted to the finger, toe or earlobe of a patient. The oximetry sensor emits light, which is scattered through a portion of the patient&#39;s tissue where blood perfuses the tissue and the light sensor photoelectrically senses the absorption of light in such tissue. The measurement of light absorbed is used to evaluate various characteristics of a patient such as oxygen saturation of hemoglobin in arterial blood, the volume of individual blood pulsations supplying the tissue, and the rate of blood pulsations corresponding to each heartbeat of a patient. 
     One kind of commonly used oximetry probe  110  is illustrated in FIGS. 1 and 2. The probe  110  comprises first and second outer shells  112 ,  114 , a spring hinge  116  at the distal end of the probe  110 , first and second extending tabs  118 ,  120 , first and second inner pads  122 ,  124 , and a cord  128  connected to the proximal end of the probe. FIG. 1 depicts the oximeter probe  110  in use. The first and second outer shells  112 ,  114  are separated by forcing the first and second extending tabs  118 ,  120  toward one another. The patient&#39;s finger or other appendage is then slipped between the first and second inner pads  122 ,  124 . On the exposed faces of the first and second inner pads  122 ,  124  are the photoemitter and photodetector used to measure various vascular conditions of the patient. The data from the photodetector is then transmitted to an attached console electrical cord  128 . 
     The spring hinge  116  is soft because excessive pressure on the finger can distort pulsations in the finger&#39;s blood supply. As a result, oximetry sensors frequently fall off the patient&#39;s finger when the patient is allowed to move unrestrained. 
     To prevent excessive movement of a finger to which the probe  110  is attached, medical personnel may secure the hand or arm to the patient&#39;s bed or a stationary object located nearby. A patient would be allowed to move the arm and hand more freely so that discomfort to the patient is avoided. To allow for the patient to move freely while not compromising the security of the oximeter probe  110  upon the finger, an additional means of securing the probe  110  to the patient is necessary. 
     Further, even small movements by the patient can cause differential motion between the oximeter probe  110  and the patient because the physical construction of the sensors renders them bulky and difficult to securely fasten to a patient&#39;s appendage. Such differential motion causes the signal received by the light sensor to be distorted, resulting in inaccurate measurements of the amount of blood constituent being evaluated. 
     In practice, reusable oximeter probes are frequently secured to the patient&#39;s appendage using adhesive tape. This method requires that the adhesive tape be applied such that sufficient pressure is applied to the patient&#39;s finger to securely fasten the oximeter probe  110 , but not so much that vasoconstriction occurs. If the practitioner creates too much or too little pressure during the initial application of the adhesive tape, it becomes necessary to remove the adhesive tape from the body of the oximeter probe  110  and replace it in a different position. Such readjustment is made difficult by the bond between the tape and the shell of the oximeter probe  110 . In addition, the residual adhesive remaining on the shell increases risk of contamination. Further, if the tape is in contact with both the patient&#39;s skin and the oximeter probe  110 , removal of the adhesive tape from the patient&#39;s skin can cause irritation, especially when the patient&#39;s skin is particularly sensitive due to trauma or age. 
     Often, when adhesive tape is used to secure an oximeter probe to the appendage of the patient, the adhesive tape stresses the structure of the oximeter probe. Such distortion occurs if the adhesive tape is not applied with substantially equal pressure on both side openings of the oximeter probe. The undue stress on the spring mechanism that results from such distortion shortens the useful life span of the oximeter probe. Additionally, use of adhesive tape to secure the oximeter probe to the patient also decreases the useful life span of the oximeter probe by making sterilization of the oximeter probe after each use difficult because of adhesive build up. When adhesive tape is removed from the oximeter probe, residue of the adhesive remains on the shell of the probe. Removing the residue may require vigorous scrubbing and/or use of abrasive cleaning agents. 
     Another concern when securing an oximeter probe to a patient is ensuring that ambient light does not interfere with the signal being received by the photodetector. Outside light is easily scattered and transmitted within the tissue toward the photodetector because skin tissue is translucent. This ambient light causes interference with the signal detected at the photodetector. 
     Further, vasoconstriction may also be caused by exposure of the appendage to the often cool outside air. Low temperature induced vasoconstriction and the resultant decrease in blood supply may significantly affect the performance of the oximeter probe. Conventional attempts to alleviate the problem of low temperature vasoconstriction include using an integral heater with the sensor and periodic massaging. Heaters, however, must be well regulated to avoid overheating. Furthermore, they increase the complexity of the sensor and can be costly. Periodic massaging can be effective, but usually requires removal of the probe while the appendage is massaged. After some massaging of the appendage to stimulate blood flow to it, the probe is reapplied and measurement resumed. It would be desirable to employ a less complex, passive means for retaining body heat that does not interrupt the measurement process. 
     SUMMARY OF THE INVENTION 
     The present invention is preferably a strap for securing an oximeter probe to an appendage of a patient. The strap is preferably made of elastic material and may be removably secured to the outside of an oximeter probe to allow for readjustment of the strap after initial application without producing excessive stress on the spring hinge of the oximeter probe. 
     In one embodiment, the strap is preferably a patch of material comprising a body, a tab located at a proximal end of the body and connected to the body of the strap by a narrow neck, an attachment mechanism for securing the body of the strap about an oximeter probe, and another attachment mechanism for securing the tab about the cord of an oximeter probe. Preferably, at a distal end of the body of the strap is a flap which has a slit through which the extending flap of the top shell of the oximeter probe may be placed to prevent excessive longitudinal movement of the strap. 
     In another embodiment of the present invention, the strap is preferably a patch of material comprising a body, a tab located at a proximal end of the body and connected to the body of the strap by a narrow neck, one attachment mechanism for securing the body of the strap, a second attachment mechanism for securing the tab and a third attachment mechanism preferably substantially perpendicular to the first and second attachment mechanisms for preventing excessive longitudinal movement of the strap. 
     In yet another embodiment of the strap, the strap preferably comprises two flaps connected by a neck, one of the flaps having a tab. The strap is secured to the oximeter probe by placing the flaps on opposing sides of the oximeter probe and placing the neck along the spring hinge at the distal end of the oximeter probe. An attachment mechanism is wrapped around the strap enclosing the body of the oximeter probe to secure the probe to an appendage of a patient while a second attachment mechanism is wrapped around the tab of the strap enclosing the cord neck of the oximeter probe to prevent excessive longitudinal movement of the strap. 
     In yet another embodiment of the present invention the strap is preferably conformed as a sock which, in use, is slipped over the oximeter probe. The strap further comprises two attachment mechanisms. One attachment mechanism is wrapped around the strap about the body of the oximeter probe so that the spring hinge is appropriately compressed on the appendage of the patient. The other is wrapped around the strap enclosing the cord neck of the oximeter probe. 
     For a fuller understanding of the nature of the present invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 is a perspective view from the proximal end of an oximeter probe. 
     FIG. 2 is a perspective view from the distal end of an oximeter probe. 
     FIG. 3 is a perspective view of a preferred embodiment of the oximeter probe strap according to the present invention. 
     FIG. 4 is a perspective view, from the proximal end of the oximeter probe, of the strap depicted in FIG. 3 in use. 
     FIG. 5 is a perspective view of a second preferred embodiment of the oximeter probe strap according to the present invention. 
     FIG. 6 is a perspective view, from the proximal end of the oximeter probe, of the strap depicted in FIG. 5 in use. 
     FIG. 7 is a perspective view, from the distal end of the oximeter probe, of the strap depicted in FIG. 5 in use. 
     FIG. 8 is a perspective view of a third preferred embodiment of the oximeter probe strap according to the present invention. 
     FIG. 9 is a perspective view, from the proximal end of the oximeter probe, of the strap depicted in FIG. 8 in use. 
     FIG. 10 is a perspective view, from the distal end of the oximeter probe, of the strap depicted in FIG. 8 in use. 
     FIG. 11 is a perspective view of a fourth preferred embodiment of the oximeter probe strap according to the present invention. 
     FIG. 12 is a perspective view, from the distal end of the oximeter probe, of the strap depicted in FIG. 11 in use. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 and 2 illustrate a reusable oximeter probe  110  commonly used in the medical industry. FIG. 1 is a perspective view taken from the proximal end of the oximeter probe  110  while attached to a patient. FIG. 2 depicts the oximeter probe  110  from the distal end in its neutral position. 
     The oximeter probe  110  comprises a first and second outer shell  112 ,  114 , a spring hinge  116  at the distal end of the probe, first and second extending tabs  118 ,  120 , first and second inner pads  122 ,  124 , a cord sleeve  126 , and a cord  128 . FIG. 1 depicts the oximeter probe in use. The first and second outer shells  112 ,  114  are separated by pressing the first and second extending tabs  118 ,  120  toward one another. The patient&#39;s finger or other appendage is then slipped between the first and second inner pads  122 ,  124 . On the inside faces of the first and second inner pads  122 ,  124  are a photoemitter and a photodetector (not shown) used to measure various vascular conditions of the patient. The data from the photodetector is then transmitted to an attached console via the cord  128 . 
     FIG. 3 is a perspective view of a preferred embodiment of an oximeter probe strap comprising a body  202 , a tab  206  located at the proximal end of the body  202 , a first attachment mechanism  210  for securing the body  202  of the strap  200 , and a second attachment mechanism  214  for securing the tab  206 . The tab  206  is preferably connected to the body  202  of the strap  200  by a preferably narrow strip  204 , the body  202 , tab  206 , and strip  204  preferably constituting a single patch of elastic material. 
     The strap may also include a flap  218  at the end opposing the strip  204 , the flap  218  having a slit  216  through which the extending tab  118  of the top shell  112  of the oximeter probe  110  may be placed, as shown in FIG.  4 . It is preferrable that the strap  200  include the flap  218  with the slit  216  so that longitudinal movement of the strap  200  along the hard outer shells  112 ,  114  of the oximeter probe  110  may be minimized. 
     The strap  200  preferably has a total length (from proximal to distal end) of approximately 3.0 inches. The width of the body  202  preferably is approximately 3.5 inches and the width of the tab  206  preferably is approximately 1.25 inches. The body  202  and the tab  206  constitute one patch of elastic material that is preferably composed of a foam laminate with brushed nylon that is hook engagable. 
     As illustrated in FIG. 4, on a surface of the body  202  of the strap  200  is the first attachment mechanism  210  for securing the strap  200  about the oximeter probe  110  such that the spring hinge  116  of the oximeter probe  110  is appropriately compressed to maintain secure contact between the inner surfaces  122 ,  124  of the oximeter probe  110  and the appendage of the patient. The first attachment mechanism  210  preferably is comprised of a patch of hook material, such as Velcro, which may be adhesively laminated  210  to the material of the strap  200  as shown in FIG.  3 . Alternatively, the first attachment mechanism  210  may be comprised of adhesive strip or a patch of hook material separate from the strap  200 . 
     On a surface of the tab  206  is a second attachment mechanism  214  for holding the strap  200  about the cord sleeve  126  of the oximeter probe  110 . Like the first attachment mechanism  210 , the second attachment mechanism  214  preferably comprises a patch of hook material, such as Velcro, which may be adhesively laminated  212  to the tab  206  as shown in FIG.  3 . Alternatively, the second attachment mechanism  214  may constitute an adhesive strip or a patch of hook material separate from the strap  200 . 
     In use, after the patient&#39;s appendage is secured in the probe  110 , the body  202  of the strap  200  may be placed over the top portion of the hard shell  112  of the oximeter probe  110  with the extending tab  118  of the top portion of the hard shell placed through the slit  216  in the flap  218  of the strap  200 . The first attachment mechanism  210  may be wrapped around the outer surface of the body  202  of the strap  200  enclosing the upper and lower hard shells  112 ,  114  of the oximeter probe  110 . The second attachment mechanism  214  may be wrapped around the tab  206 , enclosing the cord sleeve  126  of the oximeter probe  110 . 
     When hook material is used for the first and second attachment mechanisms  210 ,  212 , the attachment mechanisms can be secured directly to the elastic material that constitutes the strap  200 . When adhesive strips are used for the attachment mechanisms  210 ,  212  the strips may be placed around the entire circumference so that the opposing ends of the adhesive strips overlap to allow for a secure bond. Using hook material as the attachment mechanism may be preferred over an adhesive strip because it may facilitate to a greater degree readjustment of the first attachment mechanism  210  about the strap  200  and the oximeter probe  110 . 
     The combination of the slit  216  in the body  202  of the strap  200  and the second attachment mechanism  214  wrapped around the tab  206  enclosing the cord sleeve  126  prevents excessive longitudinal movement of the strap  200  along the hard shells  112 ,  114  of the oximeter probe  110 . Likewise, the attachment mechanism  210  of the body  202  of the strap  200  holds the oximeter probe  110  securely to the appendage of the patient by reinforcing the spring action of the spring hinge  116 . 
     FIGS. 5-7 illustrate an alternative preferred embodiment of an oximeter probe strap. FIG. 5 is a perspective view of a strap  300  alone. FIG. 6 depicts the strap  300  in use as viewed from the proximal end of the oximeter probe  110 . FIG. 7 shows the strap  300  in use as viewed from the distal end of the oximeter probe  110 . As shown in FIG. 5, strap  300  is illustrated to have some of the same components as strap  200 . Numbers with identical second and third digits represent corresponding components. 
     The body  312  of the strap  300  preferably does not have a slit  216  as does the strap  200  depicted in FIG.  3 . Instead, a third attachment mechanism  318  is attached to the body  302  of the strap  300  such that it preferably wraps around the distal end of the oximeter probe  110  and is attached to the opposite side of the body  302  of the strap  300  as shown in FIGS. 6-7. 
     The attachment mechanisms  310 ,  314 ,  318  are preferably comprised of a patch of hook material, such as Velcro, which may be adhesively laminated  308 ,  312 ,  316  to the material of the strap  300  as shown in FIG.  5 . Alternatively, the attachment mechanisms  310 ,  314 ,  318  are comprised of an adhesive strip or a patch of hook material separate from the strap  300 . 
     Referring to FIGS. 6-7, the body  302  of the strap  300  is placed over the top portion of the hard shell  112  of the oximeter probe  110 . The first attachment mechanism  310  may be wrapped around the outer surface of the body  302  of the strap enclosing the upper and lower hard shells  112 ,  114  of the oximeter probe  110 . The second attachment mechanism  314  of the tab  306  may be wrapped around the tab  306 , enclosing the cord sleeve  126  of the oximeter probe  110 . As illustrated in FIGS. 6-7, the third attachment mechanism  318  is attached  316  to the body  302  of the strap  300 , wrapped around the distal end of the oximeter probe  110  and attached to the body  302  of the strap  300  on the opposite side of the probe  110 . 
     The second attachment mechanism  314  may be placed around the tab  306  enclosing the cord sleeve  126  and the third attachment mechanism  318  may be placed around the distal end of the oximeter probe  110  to prevent excessive longitudinal movement of the strap  300  along the hard shells  112 ,  114  of the oximeter probe  110 . Likewise, the first attachment mechanism  310  of the body  302  of the strap  300  holds the oximeter probe securely to the appendage of the patient by reinforcing the spring action of the spring hinge  116 . 
     Another preferred embodiment is shown in FIGS. 8-10. This embodiment of the oximeter probe strap  400  is comprised of a first flap  402 A and a second flap  402 B, a tab  406 , a connecting neck  418 , a first attachment mechanism  410  and a second attachment mechanism  414 . The first flap  402 A and the second flap  402 B are at opposite ends of the neck portion  418  of the strap  400 . The first attachment mechanism  410  attaches to the first flap  402 A and the second attachment mechanism attaches to the tab  406 . 
     In use, the first flap  402 A of the strap  400  is placed along the side of the oximeter probe  110  where the upper and lower shells  112 ,  114  meet. The neck  418  of the strap  400  wraps around the distal end of the oximeter probe  110  and the second flap  402 B is placed along the side of the oximeter probe  110  where the upper and lower shells  112 ,  114  meet, opposite the first flap  402 A. The first attachment mechanism  410  is wrapped around the surface of the first and second flaps  402 A,  402 B, such that the spring hinge  116  of the oximeter probe  110  is secured in an appropriately compressed position. The second attachment mechanism  414  is wrapped around the surface of the tab  406  enclosing the cord sleeve  126  of the oximeter probe  110 . 
     The first and second attachment mechanisms  410 ,  414  preferably are comprised of a patch of hook material, such as Velcro, which may be adhesively laminated  408 ,  412  to the material of the strap  400  as shown in FIG.  8 . Alternatively, the first and second attachment mechanisms  408 ,  412  are comprised of an adhesive strip or a patch of hook material separate from the strap  400 . If an adhesive strip is used, it is preferably wrapped completely around the surface of the strap  400  such that opposing ends of the adhesive strip overlap to ensure a secure bond. The use of hook material for the first and second attachment mechanisms  410 ,  414  is preferred to facilitate readjustment of the attachment mechanisms  410 ,  414 . 
     Another preferred embodiment is shown in FIGS. 11-12. This embodiment of the oximeter probe strap  500  is preferably comprised of at least one patch of fabric  502  in a sock-like apparatus with an opening  530 , a first attachment mechanism  510  and a second attachment mechanism  514 . 
     FIG. 12 depicts the strap  500  in use. The strap  500  may be slid over the oximeter probe  110  such that the body of the probe enclosing the patient&#39;s appendage is inside the fabric  502  and the cord  128  exits the strap  500  through the strap opening  530 . The first attachment mechanism  510  may be wrapped around the surface of the fabric  502  as a girth enclosing the first and second outer shells  112 ,  114 , the spring hinge  116  and the first and second extending tabs  118 ,  120  of the oximeter probe strap  110  such that the spring hinge  116  of the oximeter probe  110  is secured in an appropriately compressed position about the patient&#39;s appendage. The second attachment mechanism  514  is wrapped around the fabric  502  enclosing the cord sleeve  126  of the oximeter probe  110 . 
     The first and second attachment mechanisms  510 ,  514  preferably are comprised of a patch of hook material, such as Velcro, which may be adhesively laminated  508 ,  512  to the material of the strap  502  as shown in FIG.  11 . Alternatively, the first and second attachment mechanisms  508 ,  512  are comprised of an adhesive strip or a patch of hook material separate from the strap  500 . If an adhesive strip is used, it is preferably wrapped completely around the surface of the strap  500  such that opposing ends of the adhesive strip overlap to ensure a secure bond. The use of hook material for the first and second attachment mechanisms  510 ,  514  is preferred to facilitate readjustment of the attachment mechanisms  510 ,  514 . 
     As will be understood by those skilled in the art, the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. Accordingly, the foregoing description is illustrative of the invention, but not limiting to the scope of the invention, which is set forth in the following claims.