Patent Publication Number: US-2021186459-A1

Title: Device and method for securing a transducer in position

Description:
PRIORITY 
     This application claims priority from U.S. provisional patent application Ser. No. 62/597,472 filed Dec. 12, 2017, the contents of which is incorporated in its entirety. 
    
    
     FIELD 
     The embodiments herein describe a device and method for positioning a fetal heart transducer securely against the skin of an expectant mother. 
     BACKGROUND 
     Modern medical technology enables the child birth process to be more controlled than ever before. With the development of ultrasonic technology, medical personnel can monitor a fetal heart rate (FHR) during a substantial part of the fetal life through delivery. 
     The FHR is measured using ultrasonic technology. A transducer is placed on the skin of an expectant mother. The sound waves from the pumping of the fetal heart are received by the transducer and communicated to the receiver for measurement and monitoring. In order to obtain accurate and complete FHR data, the transducer must maintain contact with the skin of the patient. 
     The fetal heart rate (FHR) is an important measure during the labor and delivery process. The loss of the FHR can cause anxiety for patients and their families, as well as concern for medical personnel. The loss of a FHR can result from the change in fetal position, the lack of contact between the fetal heart transducer and the patient&#39;s skin, or fetal distress including cardiac arrest and death. In order to intervene at the earliest sign of fetal distress, the FHR must be accurate and continuously monitored. 
     For continuous monitoring of the FHR in labor and delivery, expectant mothers are usually fitted with one or more belts worn around the torso that serve to support and hold one or more fetal heart transducers (FHT) in position. However the belts have proven to be ineffective at maintaining the fetal heart transducer position. The belts tend to move as the patient shifts position in bed. When that occurs, medical personnel is required to further adjust the FHT and re-secure it to or under the belt. 
     In addition, many expectant mothers receive an epidural during labor. As such, the belts often interfere with the epidural dressing and/or catheter itself. This can result in a dislodgement of the epidural which can result in a loss of pain medication to the mother. In addition, the belt movement in an around the epidural site can cause discomfort and/or further injury to the mother, particularly during labor. 
     Another issue relating to the FHT belt is that the belts become contaminated with blood or bodily fluids during the labor process. When this occurs, the entire belt must be changed and the FHT repositioned. The change of belts is costly in both materials and time. 
     Often times the loss of the FHR is due to the movement of the transducer caused by the movement of a support belt and/or patient movement. Movement by a patient, especially one experiencing labor pains, is expected. As a result, medical personnel, particularly labor and delivery nurses, are needed to reposition the FHT and re-secure it to the belt when there is a loss of FHR due to the mother&#39;s movement. In addition, because the belt is keeping the FHT in position, it limits a patient&#39;s movement which can be particularly uncomfortable for a mother in labor. 
     In addition, obese patients require additional care in obtaining and maintaining the FHR. The FHR is more difficult to detect in an obese patient due to the increased amount of fatty tissue surrounding the womb. Typically a labor and delivery nurse needs to spend additional time with an obese patient to first find the FHR and then to position the transducer at the location to obtain a continuous FHR reading. This process often takes more time because of the weaker signal. Loss of FHR signal also occurs in mothers with extremely contoured bellies. The significant contours make it a challenge to maintain contact between the FHT and the mother&#39;s skin. The existing belt system is often ineffective because the belt does not easily lie and hold the FHT effectively against the skin. 
     The FHR signal may also be lost during the final stages of labor. As the fetus travels down the birth canal, it places its heart at a further distance from the present FHT systems. As such, the systems are often challenged to track and maintain the FHR during these final birthing stages. In addition, because the FHR signal can be weak and difficult to track, the FHR is sometimes confused with the maternal heart rate. This can be a fatal error and create a false sense of security, especially when the fetus is in distress. 
     The monitoring of the FHR also occurs with bedridden expectant mothers. In these cases, the FHT is used to continuously monitor the FHR for a patient who has been hospitalized due to complications associated with her pregnancy. This includes premature delivery, fetal development issues and the like. 
     Some belts do not encircle the patient&#39;s torso but are one length and have two adhesive areas for securing the device to the patient. These systems do not provide for easy readjustment as the entire assembly must be removed and reapplied or replaced. In addition, the length between the two adhesive areas may lose its tension against the FHT. When this occurs, the entire assembly will need to be readjusted or replaced. 
     The existing belts and systems used to position the FHT do not provide the necessary freedom of movement needed by the patient to be comfortable and manage the labor contractions. In addition, the existing belts are often destroyed due to contamination during the labor process. This results in additional costs in time and money to the hospitals. Finally, the belts interfere with the epidural site and remove the epidural catheter due to patient movement. For these reasons, a better solution is needed to accurately position the FHT on the mother&#39;s skin but provide freedom of movement and no interference with other medical equipment. 
     Thus there is a need for an assembly for securely positioning a FHT against the skin of an expectant mother so that the assembly can be adjusted and re-adjusted without the need to remove, reapply or replace the entire assembly. In addition, there is a need for an assembly for securely positioning a FHT against the skin of an expectant mother that does not interfere with existing medical equipment. There is yet a further need for an assembly for securely positioning a FHT against the skin of an expectant mother that enables the mother to move freely with the confidence that the FHT is maintaining contact with her skin and providing continuous and accurate FHR readings. 
    
    
     
       DETAILED DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a first embodiment described herein; 
         FIG. 2  is a side sectional view of the embodiment of  FIG. 1  taken along line  2 - 2 ; 
         FIG. 3  is a bottom view of the embodiment of  FIG. 1 ; 
         FIG. 4  is a front sectional view along lines  4 - 4  of the embodiment of  FIG. 1 ; 
         FIG. 5  is a front view of the embodiment of  FIG. 1  in use; 
         FIG. 6  is a top view of the embodiment shown in  FIG. 5 ; 
         FIG. 7  is a top view of a second embodiment described herein; 
         FIG. 8  is a front sectional view of the embodiment of  FIG. 7  taken along lines  8 - 8 ; 
         FIG. 9  is a side sectional view of the embodiment of  FIG. 7  taken along lines  9 - 9 ; 
         FIG. 10  is a bottom view of the embodiment of  FIG. 7 ; 
         FIG. 11  is a front view of the second embodiment in use; 
         FIG. 12  is a top view of the embodiment of  FIG. 11 ; 
         FIG. 13  is a top view of a third embodiment described herein; 
         FIG. 14  is a front sectional view of the embodiment of  FIG. 13  along lines  14 - 14 ; 
         FIG. 15  is a bottom view of the embodiment of  FIG. 13 ; 
         FIG. 16  is a front view of the embodiment of  FIG. 13  in use; 
         FIG. 17  is a top view of the embodiment of  FIG. 16 ; 
         FIG. 18  is a front view of a wedge attachment; 
         FIG. 19  is a top view of the wedge attachment of  FIG. 18 ; 
         FIG. 20  is a side view of the wedge attachment of  FIG. 18 ; 
         FIG. 21  is a front view of the embodiment of  FIG. 18  in use; 
         FIG. 22  is a top view of the embodiment of  FIG. 21 ; and 
         FIG. 23  is a top view of the embodiment of  FIG. 22  in use with a contraction monitor. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The embodiments described herein are devices and systems for use with a medical transducer, and in particular, a fetal heart rate (FHR) transducer. The first embodiment  10  is directed to a device for securing the position of a medical transducer and is shown in  FIGS. 1-6 . Turning first to  FIG. 2 , the first embodiment  10  is shown in cross-section. The first embodiment  10  includes a button assembly  12 . The button assembly  12  includes a fabric layer  14 , cushioning layer  16 , an adhesive layer  18  and a liner  20  for the adhesive layer. 
     The fabric layer  14  of the first embodiment is preferably made of medical grade fabric. The fabric layer  14  is adhered to a cushioning layer  16 . The fabric and cushioning layers may be adhered by means of a chemical adhesive or by thermal adhesion. The cushioning layer  16  is preferably made of a medical grade foam having certain characteristics relating to compressibility, strength, and the like. The adhesive layer  18  is applied to the entire lower surface of the cushioning layer and the lower surface of the button assembly which will be described in more detail below. The liner  20  is applied to the lower surface of the adhesive layer  18  to protect it prior to use. Preferably, the liner  20  has a tab  30  extending beyond the perimeter of the fabric  14  and cushioning  16  layers. The tab  30  is designed to be easily grasped by the user to quickly remove the liner  20  and apply the first embodiment device  11  to a patient. 
     The button assembly  12  further includes a button  22 , a central stem  24 , and a button base  26 . The button assembly  12  extends through the upper surface of the fabric layer  14  and is adjacent to the cushioning layer  16 . Both the button  22  and button base  26  are substantially planar. The button base  26  is sized to be slightly larger in size than the button  22  to help stabilize the button assembly  12  during use, which will be discussed in more detail below. The stem  24  extends perpendicular between the button  22  and the button base  26 . The button  22  is sized and shaped to be received into a slot of a length of adjustable strapping having incremental slits along the length of the strapping, which will be described in more detail below. 
     The first embodiment  10  is designed to be positioned on either side of a medical transducer  32 , such as a fetal heart rate transducer, shown in its installed position in  FIGS. 5 and 6 . As shown in  FIG. 5 , the fetal heart rate transducers  32  typically have a knob  34  extending from the top of the housing  36  for use in either grasping the transducer or for positioning the transducer. The knob  34  is fixed to the housing by means of a knob stem  35 . The medical transducer  32  is typically positioned between the two devices of the first embodiment  10  using medical grade strapping  38  having incremental slits  40  along the length thereof. 
     In use, a qualified medical person manually maneuvers the medical transducer  32  over the expectant mother&#39;s abdomen to find the FHR. This can be challenging because of the mother&#39;s size, (sound waves do not travel well through significant layers of fat), and/or the position of the fetus. Often the fetus can move within the womb to avoid being near a transducer. Once a signal is found that is clear and steady, the position of the transducer  32  can be fixed. This is accomplished by first fixing the devices button assemblies  12  in place to support the position of the transducer  32  which will be described below. 
     The position at which the first button assembly (referred herein as “ 12 A” for explanatory purposes) is placed is dependent upon the desired position of the transducer  32 . If the desired transducer  32  position is atop a mother&#39;s protruding belly, then the likely position of the first button assembly  12 A would be on one side of the protruding belly. If the desired position of the transducer  32  is on the underside of a mother&#39;s protruding belly, then the position of the first button assembly  12 A may be on one side of the underside area of the belly and slightly above the transducer  32  position so as to provide some uplifting support and to use the protrusion of the belly to provide further tension. The position of the transducer  32  will differ with each patient and fetus and may change over time if the fetus or patient moves. 
     Returning to positioning the first button assembly  12 A, this is achieved by grasping the tab  30  and removing the liner  20  that protects the adhesive layer  18 . Then the user, places the first button assembly  12 A on the skin of the patient at the desired location. Looking at  FIGS. 5 &amp; 6 , that position is to the right of center on the mother&#39;s belly. The adhesive  18  sticks to the skin and enables the button assembly  12 A to remain fixed in that position. 
     After the first button assembly  12 A is positioned, the position of the second button assembly  12 B is determined. Typically, the position of the second button assembly  12 B would be on the opposite side of the first button assembly  12 A from the FHR transducer  32 . The second button assembly  12 B is attached to the patient&#39;s skin as described above by removing the liner  20  and placing it on the skin of the patient. Looking at  FIGS. 5 &amp; 6 , that position is to the left of center on the mother&#39;s belly. 
     A length of strapping  38  is cut to accommodate the length between the two devices  12 A, B. A slit  40  midway along the length of the strapping  38  is received into the knob  34  of the transducer  32 . Subsequently, a slit  40  at one end of the strapping  38  is received into the button  22  of the first button assembly  12 A. A slit  40  at the opposing end of the strapping  38  is received into the button  22  of the second button assembly  12 B. The slits  40  received into the buttons  22  of the devices  11  and into the knob  34  of the transducer  32  may all be moved and new slits received into the respective buttons to adjust the tension of the strapping  38  to provide greater support to the transducer and ensure that its position is secure. 
     The tension in the strapping  38  between the transducer  32  and the first and second button assemblies  12 A, B maintains a pressure on the transducer that enables the transducer to remain fixed in the desired position. This frees up medical personnel to attend to other matters secure in the knowledge that the transducer  32  is in a secure position and is providing continuous fetal vital signs to the monitor [not shown]. This also provides the expectant mother with some level of freedom in that she is able to move about her bed and change positions without fear of losing the signal from the transducer  32 . So long as the signal remains strong, the transducer  32 , fixed in position, will be able to communicate the signal to the monitor. The continual readings from the transducer  32  provide medical personnel with continually updated fetal data. This provides both medical personnel and the mother with a sense of confidence that the fetal health and well being is being continuously monitored. 
     A second embodiment  50  is designed to work with fetal monitor belts having Velcro straps and is shown in  FIGS. 7-12 . The second embodiment  50  includes a pair of second embodiment devices  52 A, B, shown in  FIGS. 11 &amp; 12 . Turning now to  FIG. 7 , each device  52  includes a belt loop  54  fixed to the surface of a patch of fabric  56  having an upper fabric side  55  and a lower fabric side  57 , as shown in  FIG. 8 . The belt loop  54  has a support member  58  located beneath the lower fabric side  57 . A cushioning layer  60  is located to each side and below the support member  58  and adjacent to a portion of the lower fabric side  57 . A layer of adhesive  62  extends below the cushioning layer  60  and the lower fabric side  57  not covered by the cushioning layer. A liner  64  covers the adhesive  62  until use. The liner  64  has a tab  66  extending outwardly from the profile of the fabric  56 . The tab  66  is designed to be able to be easily grasped during use, which will be explained in detail below. 
     The second embodiment  50  works similarly to the first embodiment  10  in that a pair of the second embodiment devices  52 A, B are used to anchor a medical transducer, typically a fetal heart rate transducer  32  in a fixed position. The second embodiment  50  is used when the particular brand of fetal heart rate transducer  32  has Velcro straps  68  fixed to or extending therefrom. These include the General Electric Corometric™ series. Once the position of the FHR transducer  32  is known, a first device  52 A is positioned to one side of the FHR transducer  32  similarly as described above for the first embodiment device  10 . Once the first device is positioned  52 A against the skin of the patient, a second device  52 B is positioned in an opposing direction with the transducer  32  to be located therebetween. After the second device  52 B is fixed against the patient&#39;s skin, the Velcro strapping  68  is slipped through the belt loop  54  of the first second embodiment device  52 A. The remaining length of the strapping  64  is folded back against the strapping and, due to the loop and hook nature of Velcro, it is secured against itself. The final positioning of the FHR transducer  32  and devices  52 A and B is shown in  FIGS. 11 and 12 . 
     It should be noted that the second embodiment  50  shows the belt loop  54  located at the mid-section of the length of the second embodiment device  52 . However, it is contemplated that the belt loop may be positioned closer to one end of the second embodiment device  52  to provide for a greater area of adhesion to hold the second embodiment device  52  in position when tensioned in use. 
     A third embodiment  90  is shown in  FIGS. 13-17 . The third embodiment  90  is similar to the first embodiment  10  except that the button  92  assembly of the third embodiment is located at a position off-center relative to the fabric layer  94 , as shown in  FIGS. 13-15 . The third embodiment  90  is a device  91  having a button assembly  92 , and fabric  94 , cushion  96 , adhesive  98  and liner  100  layers. The button assembly  92  of the third embodiment  90  includes a third embodiment button  102 , a button stem  104  and a button base  106 . The button assembly  92  is positioned so that the fabric layer  94  covers the upper surface of the button base  106 . The cushion layer  96  covers the lower surface of the button base  106 . The adhesive layer  98  covers the cushion layer and the lower surface of the fabric layer  94 . The liner  100  covers the adhesive layer  98  until use. 
     The button assembly  92  of the third embodiment device  91  is mounted off center relative to the fabric layer. As can be seen in  FIG. 13 , the button assembly is closer to one end of the length of the fabric layer than the other end. The off-center positioning of the button assembly  92  on the fabric layer  94  allows a greater area of the adhesive layer  98  to be applied to the patient&#39;s skin on the side opposite from where the transducer is located. The greater adhesive area helps to anchor the device  91  against the tension force created by the strapping  38  which pulls on the device  91  in a direction towards the transducer  32 . 
     In use, once the position of the transducer  32  is set, the first, third embodiment device  91 A is positioned by removing the liner  100  from the lower surface of the adhesive layer  98 . The first third embodiment device  91 A is positioned so that the button  102  is closer to the transducer  32  location. The second third embodiment device  91 B is secured in the same fashion as described above but in a direction opposite from the location of the first third embodiment device  91 A and on the opposed side of the transducer  32 , as shown in  FIGS. 16 and 17 . This embodiment enables the devices  91 A, B to withstand the tension imposed on each device by the strapping  38  while maintaining the position of the transducer  32 . 
     Another component that may be used with either the first  10  or third  90  embodiments is a wedge attachment  70 , as shown in  FIGS. 18-22 . As an example, the wedge attachment as described herein will be used with the third embodiment. However, the wedge attachment  70  is also able to be used with the first embodiment  10 . The wedge attachment  70  is made of a rigid material that can be maintain its shape when used in conjunction with the first  10  or third  90  embodiments. The wedge attachment  70  is preferably made of a medical grade polymer for easy cleaning. 
     The wedge attachment  70  has a body  72  fixed to a circular platform  74 , as shown in  FIG. 19 . The platform  74  has a radial slit  76  extending from the edge to the center of the platform. The center of the platform  74  has a small circular void  78 . The void  78  is designed to be received by a standard FHR transducer, as will be described in more detail below. The platform  74  also has a lip  73  extending downwardly around the edge thereof, as shown in  FIG. 18 . The platform  74  further includes an undersurface  77  preferably made of a non-slip material such as rubber or a non-slip polymer. 
     FHR transducers are typically disc-shaped and have a standard size. Thus the wedge attachment  70  can be manufactured and scaled to be received by standard disc-shaped FHR transducers. The circular shape of the platform  74  is designed to rest on the upper surface of a standard fetal heart rate transducer  75 . The circular void  78  is designed to receive the knob stem  35  located on a standard fetal heart rate transducer  75 . 
     The wedge body  72  is located off center relative to the circular platform  74 , as shown in detail in  FIG. 18 . The body  72  is sloped and has a substantially sinusoidal profile in both the front and side aspects, see also  FIG. 20 . Returning to  FIG. 18 , the body has front left  82  and front right  84  slopes, and side left  86  and side right  88  slopes, shown in  FIG. 20 . A wedge button  89  is fixed to the top of the body  72 . The wedge button  89  has a disc shaped upper portion  92  fixed to a base  94  fixed to the wedge body  72 , as shown in  FIG. 19 . The wedge button  89  is sized and shaped similarly to the FHR transducer knob  34 . 
     To use, the wedge attachment  70  must first be positioned over the FHR transducer  75 . To fit the wedge attachment over the FHR transducer  75 , the radial slit  76  is pulled apart to enable the FHR transducer knob stem  35  to receive the slit  76  on either side thereof and then the stem  35  rests within the wedge void  78 . In this position, the FHR transducer  75  rests beneath the wedge attachment  70  and the lip  73  of the platform  74  extends downwardly around the outer edge of the upper surface of the transducer to hold the transducer  75  in place. The non-slip material of the undersurface  77  grips the upper surface of the transducer  75  so that wedge attachment  70  and FHR transducer the two operate as one unit. 
     Once the wedge attachment  70  is fixed over the FHR transducer  75 , the position of the FHR transducer is determined. This may involve moving the FHR transducer  75  and wedge attachment  70  around until the FHR signal is strong. Once the position is determined, the position of each of the devices  91 A and B, of the third embodiment are determined. Once the position of each third embodiment device  91  is determined, the liner  20  is removed from the first third embodiment device  91 A and placed against the skin of an expecting mother with the button  102  positioned closer to the FHR transducer  75 . Subsequently the second third embodiment device  91 B is positioned by removing the liner  20  and placing the embodiment on the skin at the desired location. It should be noted that the button  102  of the second third embodiment device  91  should be positioned closer to the desired location of the transducer  75 . 
     Next, a slit  40  along the midpoint in a length of strapping  38  is received into the wedge button  89 . A slit  40  at a first end of the strapping  38  subsequently receives the button  102  from the first third embodiment device  91 A, and a slit at the other end of the strapping receives the button from the second third embodiment device  91 B. The strapping tension may then be adjusted by changing the slit that is received into the button  102  on either third embodiment device  910  and also on the wedge button  89 . The off-center aspect of the wedge attachment  70  causes an uneven distribution of the tension force created in the strapping  38 . This results in an angling of the wedge attachment  70  which also results in an angling of the FHR transducer fixed thereunder. Thus, the wedge attachment  70  enables the FHR transducer  75  to maintain an angled position relative to the skin surface. This angled position is often extremely advantageous for obtaining and maintaining the FHR because the fetus may be in a position that is not easily measured when the FHT is placed flat against the mother&#39;s skin. The position and extent of the angled FHR transducer  75  can be adjusted by increasing or decreasing the tension in the strapping  38  and also by rotating the wedge attachment  70  so that the force is redistributed and thus the angle of the FHR transducer relative to the skin surface is changed. 
     It should also be noted that in this example and in other configurations, additional devices may be added to the configuration to further stabilize the position of the FHR. This is done by positioning the additional device, or devices and connecting them to the FHR transducer by means of the strapping  38 . The strapping  38  is received into the device button and into the transducer knob  34  to provide further tension on the configuration and thus stabilize the position of the FHR transducer. 
     One example of an arrangement involving the FHT and an additional device is shown in  FIG. 23 . The arrangement includes the addition of a compression monitor (“CM”)  110 . The compression monitor is similar to an FHT in that it is a transducer that monitors the labor contractions of the mother. The CM includes a button  112  to receive a slot  40  in the strapping  38 . During labor and delivery, it is common practice to concurrently apply both a CM  110  and an FHT  32  to the skin surface of a mother, as shown in  FIG. 23 . 
     As discussed above, the plurality of devices connected by strapping help to create an infinite number of configurations for the positioning of the FHR transducer. The rotation of the wedge attachment  70  about the upper surface of the FHR transducer, or other device, helps to create an infinite number of positions of the FHR transducer, or other device, relative to the skin surface of the mother. 
     Between the device configurations and the wedge attachment rotation, medical personnel are able to customize a configuration for each patient based on the patient&#39;s anatomy and position as well as the fetal location and position. This system provides accurate and continuous FHR monitoring on an individualized basis and frees up medical personnel to attend to other, often more urgent matters. The system further provides a level of freedom to the mother to enable her to move freely within her bed or even stand and walk around while securing the FHR transducer in the desired position.