Device and method for securing a transducer in position

An assembly and method for positioning a fetal heart transducer against skin. The assembly includes a strip having first and second ends and openings along its length, first and second fixation devices, each device having first and second surfaces, the first surface having adhesive thereon. A protuberance extends outwardly from the second surface. The assembly includes a fetal heart transducer. The first fixation device is secured to the skin at a first location and the protuberance of the first fixation device is received into a first opening on the first end of the strip. The first surface of the second fixation device is secured to the skin at a second location and the protuberance of the second fixation device is received into a second opening on the second end of the strip. The fetal heart transducer is secured between first and second fixation devices and beneath the strip.

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'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's movement. In addition, because the belt is keeping the FHT in position, it limits a patient'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'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'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'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 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 embodiment10is directed to a device for securing the position of a medical transducer and is shown inFIGS.1-6. Turning first toFIG.2, the first embodiment10is shown in cross-section. The first embodiment10includes a button assembly12. The button assembly12includes a fabric layer14, cushioning layer16, an adhesive layer18and a liner20for the adhesive layer.

The fabric layer14of the first embodiment is preferably made of medical grade fabric. The fabric layer14is adhered to a cushioning layer16. The fabric and cushioning layers may be adhered by means of a chemical adhesive or by thermal adhesion. The cushioning layer16is preferably made of a medical grade foam having certain characteristics relating to compressibility, strength, and the like. The adhesive layer18is 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 liner20is applied to the lower surface of the adhesive layer18to protect it prior to use. Preferably, the liner20has a tab30extending beyond the perimeter of the fabric14and cushioning16layers. The tab30is designed to be easily grasped by the user to quickly remove the liner20and apply the first embodiment device11to a patient.

The button assembly12further includes a button22, a central stem24, and a button base26. The button assembly12extends through the upper surface of the fabric layer14and is adjacent to the cushioning layer16. Both the button22and button base26are substantially planar. The button base26is sized to be slightly larger in size than the button22to help stabilize the button assembly12during use, which will be discussed in more detail below. The stem24extends perpendicular between the button22and the button base26. The button22is 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 embodiment10is designed to be positioned on either side of a medical transducer32, such as a fetal heart rate transducer, shown in its installed position inFIGS.5and6. As shown inFIG.5, the fetal heart rate transducers32typically have a knob34extending from the top of the housing36for use in either grasping the transducer or for positioning the transducer. The knob34is fixed to the housing by means of a knob stem35. The medical transducer32is typically positioned between the two devices of the first embodiment10using medical grade strapping38having incremental slits40along the length thereof.

In use, a qualified medical person manually maneuvers the medical transducer32over the expectant mother's abdomen to find the FHR. This can be challenging because of the mother'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 transducer32can be fixed. This is accomplished by first fixing the devices button assemblies12in place to support the position of the transducer32which will be described below.

The position at which the first button assembly (referred herein as “12A” for explanatory purposes) is placed is dependent upon the desired position of the transducer32. If the desired transducer32position is atop a mother's protruding belly, then the likely position of the first button assembly12A would be on one side of the protruding belly. If the desired position of the transducer32is on the underside of a mother's protruding belly, then the position of the first button assembly12A may be on one side of the underside area of the belly and slightly above the transducer32position so as to provide some uplifting support and to use the protrusion of the belly to provide further tension. The position of the transducer32will differ with each patient and fetus and may change over time if the fetus or patient moves.

Returning to positioning the first button assembly12A, this is achieved by grasping the tab30and removing the liner20that protects the adhesive layer18. Then the user, places the first button assembly12A on the skin of the patient at the desired location. Looking atFIGS.5&6, that position is to the right of center on the mother's belly. The adhesive18sticks to the skin and enables the button assembly12A to remain fixed in that position.

After the first button assembly12A is positioned, the position of the second button assembly12B is determined. Typically, the position of the second button assembly12B would be on the opposite side of the first button assembly12A from the FHR transducer32. The second button assembly12B is attached to the patient's skin as described above by removing the liner20and placing it on the skin of the patient. Looking atFIGS.5&6, that position is to the left of center on the mother's belly.

A length of strapping38is cut to accommodate the length between the two devices12A, B. A slit40midway along the length of the strapping38is received into the knob34of the transducer32. Subsequently, a slit40at one end of the strapping38is received into the button22of the first button assembly12A. A slit40at the opposing end of the strapping38is received into the button22of the second button assembly12B. The slits40received into the buttons22of the devices11and into the knob34of the transducer32may all be moved and new slits received into the respective buttons to adjust the tension of the strapping38to provide greater support to the transducer and ensure that its position is secure.

The tension in the strapping38between the transducer32and the first and second button assemblies12A, 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 transducer32is 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 transducer32. So long as the signal remains strong, the transducer32, fixed in position, will be able to communicate the signal to the monitor. The continual readings from the transducer32provide 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 embodiment50is designed to work with fetal monitor belts having Velcro straps and is shown inFIGS.7-12. The second embodiment50includes a pair of second embodiment devices52A, B, shown inFIGS.11&12. Turning now toFIG.7, each device52includes a belt loop54fixed to the surface of a patch of fabric56having an upper fabric side55and a lower fabric side57, as shown inFIG.8. The belt loop54has a support member58located beneath the lower fabric side57. A cushioning layer60is located to each side and below the support member58and adjacent to a portion of the lower fabric side57. A layer of adhesive62extends below the cushioning layer60and the lower fabric side57not covered by the cushioning layer. A liner64covers the adhesive62until use. The liner64has a tab66extending outwardly from the profile of the fabric56. The tab66is designed to be able to be easily grasped during use, which will be explained in detail below.

The second embodiment50works similarly to the first embodiment10in that a pair of the second embodiment devices52A, B are used to anchor a medical transducer, typically a fetal heart rate transducer32in a fixed position. The second embodiment50is used when the particular brand of fetal heart rate transducer32has Velcro straps68fixed to or extending therefrom. These include the General Electric Corometric™ series. Once the position of the FHR transducer32is known, a first device52A is positioned to one side of the FHR transducer32similarly as described above for the first embodiment device10. Once the first device is positioned52A against the skin of the patient, a second device52B is positioned in an opposing direction with the transducer32to be located therebetween. After the second device52B is fixed against the patient's skin, the Velcro strapping68is slipped through the belt loop54of the first second embodiment device52A. The remaining length of the strapping64is 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 transducer32and devices52A and B is shown inFIGS.11and12.

It should be noted that the second embodiment50shows the belt loop54located at the mid-section of the length of the second embodiment device52. However, it is contemplated that the belt loop may be positioned closer to one end of the second embodiment device52to provide for a greater area of adhesion to hold the second embodiment device52in position when tensioned in use.

A third embodiment90is shown inFIGS.13-17. The third embodiment90is similar to the first embodiment10except that the button92assembly of the third embodiment is located at a position off-center relative to the fabric layer94, as shown inFIGS.13-15. The third embodiment90is a device91having a button assembly92, and fabric94, cushion96, adhesive98and liner100layers. The button assembly92of the third embodiment90includes a third embodiment button102, a button stem104and a button base106. The button assembly92is positioned so that the fabric layer94covers the upper surface of the button base106. The cushion layer96covers the lower surface of the button base106. The adhesive layer98covers the cushion layer and the lower surface of the fabric layer94. The liner100covers the adhesive layer98until use.

The button assembly92of the third embodiment device91is mounted off center relative to the fabric layer. As can be seen inFIG.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 assembly92on the fabric layer94allows a greater area of the adhesive layer98to be applied to the patient's skin on the side opposite from where the transducer is located. The greater adhesive area helps to anchor the device91against the tension force created by the strapping38which pulls on the device91in a direction towards the transducer32.

In use, once the position of the transducer32is set, the first, third embodiment device91A is positioned by removing the liner100from the lower surface of the adhesive layer98. The first third embodiment device91A is positioned so that the button102is closer to the transducer32location. The second third embodiment device91B is secured in the same fashion as described above but in a direction opposite from the location of the first third embodiment device91A and on the opposed side of the transducer32, as shown inFIGS.16and17. This embodiment enables the devices91A, B to withstand the tension imposed on each device by the strapping38while maintaining the position of the transducer32.

Another component that may be used with either the first10or third90embodiments is a wedge attachment70, as shown inFIGS.18-22. As an example, the wedge attachment as described herein will be used with the third embodiment. However, the wedge attachment70is also able to be used with the first embodiment10. The wedge attachment70is made of a rigid material that can be maintain its shape when used in conjunction with the first10or third90embodiments. The wedge attachment70is preferably made of a medical grade polymer for easy cleaning.

The wedge attachment70has a body72fixed to a circular platform74, as shown inFIG.19. The platform74has a radial slit76extending from the edge to the center of the platform. The center of the platform74has a small circular void78. The void78is designed to be received by a standard FHR transducer, as will be described in more detail below. The platform74also has a lip73extending downwardly around the edge thereof, as shown inFIG.18. The platform74further includes an undersurface77preferably 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 attachment70can be manufactured and scaled to be received by standard disc-shaped FHR transducers. The circular shape of the platform74is designed to rest on the upper surface of a standard fetal heart rate transducer75. The circular void78is designed to receive the knob stem35located on a standard fetal heart rate transducer75.

The wedge body72is located off center relative to the circular platform74, as shown in detail inFIG.18. The body72is sloped and has a substantially sinusoidal profile in both the front and side aspects, see alsoFIG.20. Returning toFIG.18, the body has front left82and front right84slopes, and side left86and side right88slopes, shown inFIG.20. A wedge button89is fixed to the top of the body72. The wedge button89has a disc shaped upper portion92fixed to a base94fixed to the wedge body72, as shown inFIG.19. The wedge button89is sized and shaped similarly to the FHR transducer knob34.

To use, the wedge attachment70must first be positioned over the FHR transducer75. To fit the wedge attachment over the FHR transducer75, the radial slit76is pulled apart to enable the FHR transducer knob stem35to receive the slit76on either side thereof and then the stem35rests within the wedge void78. In this position, the FHR transducer75rests beneath the wedge attachment70and the lip73of the platform74extends downwardly around the outer edge of the upper surface of the transducer to hold the transducer75in place. The non-slip material of the undersurface77grips the upper surface of the transducer75so that wedge attachment70and FHR transducer the two operate as one unit.

Once the wedge attachment70is fixed over the FHR transducer75, the position of the FHR transducer is determined. This may involve moving the FHR transducer75and wedge attachment70around until the FHR signal is strong. Once the position is determined, the position of each of the devices91A and B, of the third embodiment are determined. Once the position of each third embodiment device91is determined, the liner20is removed from the first third embodiment device91A and placed against the skin of an expecting mother with the button102positioned closer to the FHR transducer75. Subsequently the second third embodiment device91B is positioned by removing the liner20and placing the embodiment on the skin at the desired location. It should be noted that the button102of the second third embodiment device91should be positioned closer to the desired location of the transducer75.

Next, a slit40along the midpoint in a length of strapping38is received into the wedge button89. A slit40at a first end of the strapping38subsequently receives the button102from the first third embodiment device91A, and a slit at the other end of the strapping receives the button from the second third embodiment device91B. The strapping tension may then be adjusted by changing the slit that is received into the button102on either third embodiment device910and also on the wedge button89. The off-center aspect of the wedge attachment70causes an uneven distribution of the tension force created in the strapping38. This results in an angling of the wedge attachment70which also results in an angling of the FHR transducer fixed thereunder. Thus, the wedge attachment70enables the FHR transducer75to 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's skin. The position and extent of the angled FHR transducer75can be adjusted by increasing or decreasing the tension in the strapping38and also by rotating the wedge attachment70so 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 strapping38. The strapping38is received into the device button and into the transducer knob34to 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 inFIG.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 button112to receive a slot40in the strapping38. During labor and delivery, it is common practice to concurrently apply both a CM110and an FHT32to the skin surface of a mother, as shown inFIG.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 attachment70about 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'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.