WO2016038195A1

WO2016038195A1 - Vacuum assisted fetal extractor

Info

Publication number: WO2016038195A1
Application number: PCT/EP2015/070853
Authority: WO
Inventors: Niels Kornerup; David Gjaldbæk THORMAR
Original assignee: Lina Medical Aps
Priority date: 2014-09-11
Filing date: 2015-09-11
Publication date: 2016-03-17

Abstract

An obstetrical vacuum device comprising a cup which can be attached to a fetal scalp and facilitate extraction of fetus from the birth canal. To increase the ability of the surgeon to handle the cup and position the cup on the fetal scalp without injuring or irritating the mucous membrane, the cup has an outer surface with a hydrophilic surface portion.

Description

VACUUM ASSISTED FETAL EXTRACTOR Field of the invention

The present invention relates to an obstetrical vacuum assisted fetal extractor. Particularly, the invention relates to an obstetrical vacuum device comprising a cup forming a chamber with an opening and a sealing flange about the opening for establishing sealing contact with a fetal scalp. The device to which the invention relates further comprises a pump for establishing a pressure difference between an internal pressure in the chamber and an external pressure in an ambient space,

Background of the invention During childbirth, the birth mother or midwife is sometimes unable to deliver the fetus without assistance, for example, in conditions of dystocia (i.e., slow or difficult labour or delivery), uterine inertia, maternal exhaustion, maternal distress, or fetal distress. Such assistance generally entails the use of a device to aid in the delivery of the fetus. These devices may likewise be required to assist a physician during particularly difficult Caesarean sections.

One example of such a device is forceps. Forceps, however, tend to be bulky and difficult to operate. In addition, the use of forceps, at the very least, is uncomfortable for both the mother and the fetus and risks injury to both.

Alternative devices to forceps are obstetrical vacuum extractors. Conventional obstetrical vacuum extractor systems utilize a cup, which may be placed onto the fetal head, an elongated traction device with a handle for applying the traction force, and, traditionally, an elongated tube coupled at one end to the interior of the cup and the other end to an electrical floor based or a hand-held vacuum pump. Operation of the hand-held vacuum pump results in the development of a vacuum between the cup and the fetal head, which is then used to manoeuvre and extract the fetus from the birth canal by pulling the gripping device in an appropriate direction. The tube may be coupled directly to the cup or coupled to an elongated hollow stem, which acts as the traction device.

More recently, unitary obstetrical vacuum extractor devices have been developed which include a vacuum extractor cup integrated with a hand-held pump and pulling handle. In this way, once properly placed on the fetal head, the physician can both apply an extraction force and manoeuvre the cup while applying and maintaining a vacuum within the cup, all with the same hand. Such devices are disclosed in, for example, U. S. Patent No. 5,395,379 and U. S. Patent No. 6,074,399. From U.S. Patent No. 4,730,617 is known a vacuum extractor with two vessel chambers, each of which is evacuable separately.

While vacuum assisted fetal extractors have provided many advantages in the delivery of a fetus from its mother, such devices also pose potential hazards if not properly utilized or adequately monitored during their use. Such hazards stem from the fact that the fetal skull is soft and structurally weak and thus renders the head of the fetus susceptible to deformation or injury during childbirth.

Misapplication or improper use of a vacuum assisted fetal extractor may also result in a number of injuries to the fetus. Such injuries may, by way of example, include subdural hematoma, subgaleal hemorrhage, abrasions, as well as other less common injuries. While it is not an exhaustive list, injuries of the above listed type may be the result of improper placement of the vacuum cup on the fetal head.

The cup is typically handled manually. I.e. the surgeon, midwife, or other trained staff holds the cup in the hand, introduces the cup into the birth canal, and holds the sealing flange against the fetal scalp while the pump is operated until the pressure in the chamber is sufficiently low to keep the cup fixed on the scalp. The cup should preferably be easily manipulated in the birth canal to support correct placement on the fetal skull.

The mucous membrane of the birth canal is fragile, and manipulation of the cup may damage or cause irritation, particularly during continuous manipulation of the cup.

Description of the invention

It is an object of embodiments of the invention to provide an improved vacuum assisted fetal extractor. Particularly, it is an object of the invention to reduce the risk of injuring the birth canal during handling of the cup and subtraction of the child.

According to a first aspect, the invention provides an obstetrical vacuum device of the kind mentioned in the field of the invention and where a portion of the outer surface of the cup, facing away from the chamber, is hydrophilic. Due to the hydrophilic outer surface, the surface friction of the cup against the surface of the birth canal can be reduced significantly, and the cup becomes movable with reduced interaction with the mucous membrane whereby irritation and potential damage can be reduced or avoided. By hydrophilic is herein meant that the surface is capable of absorbing water or a water based liquid substance and to swell thereby such that a low friction surface coefficient is created. Accordingly, the surface could be the surface of any such hydrophilic material known in the art, e.g. a material comprising PvP.

Structural parts of the cup, e.g. the entire cup, may be made from such a hydrophilic material, or the outer surface could be coated with a thin layer of such a hydrophilic material. Particularly, the coating may constitute less than 1 percent of the mass or volume of the entire cup or even of the entire vacuum device.

Since a hydrophilic surface may become very slippery and therefore difficult to handle, the outer surface may additionally comprise at least one non-hydrophilic surface portion which can be gripped and used for manipulation of the cup.

The hydrophilic surface portions may cover in the range of 25-75 percent of the outer surface, and they may particularly cover edges, corners or other distinct structures which may potentially damage the birth canal.

Particularly, the hydrophilic surface portions may cover any part where the outer surface has a curve with a radius less than 10 mm. This may protect the mucous membrane against sharp edges on the cup and effectively facilitate sliding between relatively sharp corners or edges and the birth canal.

The sealing flange of the cup forms a lip or edge which can be arranged against the scalp and thereby seal the chamber. By definition herein, the sealing flange defines an attachment plane along which the sealing flange is supposed to contact the fetal scalp. The direction referred to herein as "upwards direction" is a direction perpendicular to the attachment plane. The sealing flange may define a sealing plane, and at least one of the first and second portions may be parallel with the sealing plane. The sealing flange may not necessarily be hydrophilic. In fact, a non-hydrophilic sealing flange may increase the bond to the fetal scalp. The cup forms a height being its dimension in the upward direction perpendicular to the attachment plane. It may be an advantage to use a low-profile cup which herein means that the height is less than one third of the largest dimension of the cup in the attachment plane or even less than one fourth or one fifth of the largest dimension in the attachment plane.

The crosswise direction is herein defined as a direction perpendicular to the upwards direction. The cup may have a largest crosswise dimension in the crosswise direction in the range of 100-150 per cent of the largest dimension of the cup in the attachment plane.

The cup could be made of an elastically deformable and relatively soft material which easily adapts to the shape of the fetal scalp, e.g. from a soft rubber or plastic material.

Alternatively, the cup could be made of a more rigid and less elastically deformable material whereby the fetal scalp will typically take the form of the cup. As an example, the cup could be made of steel, or a rigid plastic material. The cup, and particularly the rigid type of cup, could be provided with a soft resilient lip to form the sealing flange. This may provide a stronger or more air-tight seal against the scalp.

Particularly, the cup and the pump may be connected by a tube which can establish fluid communication between the pump and cup, or by a flexible cable allowing reorientation of the pump relative to the cup. The pump may thereby serve as a handle by which the cup and thus the fetus can be pulled. The flexible tube or cable may e.g. comprise a combined suction tube for communication of suction from the pump to the chamber and a wire extending along the tube or inside the tube for axially strengthening of the cabled connection and thereby allowing for a stronger pull. At least a portion of the tube may have a hydrophilic surface. The outer surface of the cup may have a stepped configuration which includes at least one step separating a first distinct surface portion from a second distinct surface portion. In this embodiment, one of the surface portions may have hydrophilic characteristics, whereas the other surface portion may have non-hydrophilic characteristics. The non-hydrophilic characteristics could be obtained e.g. by only applying the hydrophilic material to one of the surface portions, or by removing applied hydrophilic material from the other surface portion.

Such a step may provide tactile indication of the orientation of the cup, and the step may improve the grip by which the user, e.g. with a tip of a finger, can push the cup sideways, and the step thereby enables a more exact positioning of the cup on the scalp. The stepped configuration of the outer surface therefore facilitates handling even with a slim cup or with a cup having at least a slim portion. By "stepped configuration" is herein meant that the outer surface has at least two distinct and bordering surface portions separated by a step whereby the surface portions, herein first and second portions, are in different levels and thus at different distances to the sealing flange. The first and second surface portions may be plane and optionally parallel to each other.

Herein, "perpendicular distance" is a distance in a direction perpendicular to the sealing plane in the upward direction. The first portion of the outer surface is at a first perpendicular distance over the sealing flange and the second portion of the outer surface is at a second perpendicular distance over the sealing flange. The second perpendicular distance could e.g. be larger than the first perpendicular distance, and optionally, the first perpendicular distance could be larger than the difference between the second and first perpendicular distances.

The stepped configuration provides a third portion of the outer surface, which third portion connects the first and second portions. This, third, surface portion forms the step and is therefore not parallel to the first and second surface portions. In one embodiment, the third surface portion is perpendicular to the first and second surface portions, and in another embodiment, the third surface portion is within plus or minus 10-20 degrees or even less than plus or minus 10 degrees from being perpendicular to the first and second portions, e.g. at an angle between 75-105 degrees to one of the first and second portions. In one embodiment, the second surface portion has a hydrophilic surface whereas the first and third surface portions are not hydrophilic. In another embodiment, the first and second surface portions have a hydrophilic surface whereas the third surface portion is not hydrophilic. This may reduce the surface friction of the less slim portion of the cup and simultaneously provide a good grip in the other non-hydrophilic surface portions. In one embodiment, at least one of the first, second, and third surface portion is hydrophilic while the sealing flange is non-hydrophilic. This may facilitate adherence between the sealing flange and the fetal scalp. For this purpose, the sealing flange may form part of a flange component which is made as an individual component being attached e.g. adhesively to the remaining part of the cup. To further facilitate gripping and handling of the cup, one or more of the first, second, and/or third surface portions may include a surface texture which increases surface friction, e.g. in the form of ribs, or ridges, depressions, knobs, or similar surface features. This may particularly be provided on the third and/or the first surface portion. Particularly, the device may comprise a continuous surface pattern which extends from the first surface portion into the third surface portion to thereby provide a tactile indication for the user and thereby allow the user to feel where the cup is touched by the fingers. This allows improved handling when the cup is inside the birth canal. The continuous surface pattern could e.g. be a circular ridge or depression. Particularly, such ridge or depression may be non-hydrophilic.

To further improve the ability to handle the cup, the third portion may form a plurality of cavities of a size facilitating engagement with fingertips. The pump may, as mentioned above, be connected to the cup by a hollow tube. To provide a low profile of the cup and tube, the tube may extend through the outer surface outside the first and second portions, e.g. through the third portion, and e.g. at an angle different from 90 degrees to the first and second surface portions. The tube may e.g. extend through the outer surface in a direction being essentially parallel to one of the first and second surface portions, and particularly, it may be parallel to the first surface portion.

In a second aspect, the invention provides a method of operating a device according to the first aspect of the invention. The method comprises the step of wetting at least one of the hydrophilic surface portions prior to insertion of the cup into a patient.

The method may further comprise the step of inserting the cup into a birth canal and attaching it to a fetal scalp while manipulating the cup by contact between the fingers and the third surface portion which constitutes the step of the aforementioned stepped configured outer surface of the cup.

In additional aspects, the invention provides an alternative series of embodiments.

It is an object of the alternative embodiments of the invention to provide an improved vacuum assisted fetal extractor. Particularly, it is an object to increase handling of the cup and to facilitate improved gripping and manoeuvrability of the cup in the birth canal.

According to the alternative aspect, the invention provides an obstetrical vacuum device of the kind mentioned in the field of the invention and where an outer surface of the cup, facing away from the chamber, has a stepped configuration. Due to the stepped configuration, the user obtains several advantages. Firstly, the step provides tactile indication of the orientation of the cup. Secondly, the step may improve the grip by which the user, e.g. with a tip of a finger, can push the cup sideways, and the step thereby enables a more exact positioning of the cup on the scalp. Thirdly, the step facilitates rotation of the cup - again by allowing the cup to be pushed by the fingertips of the surgeon, Fourthly, the stepped configuration may provide one portion with a slim shape, and an adjacent portion being less slim and therefore more easily manoeuvrable, and the stepped configuration thereby combines the advantage of a slim shape with the advantage of a less slim shape.

Accordingly, the stepped configuration of the outer surface facilitates handling even with a slim cup or with a cup having at least a slim portion. Brief description of the drawings

Embodiments of the invention will now be further described with reference to the drawings, in which:

Fig. 1 illustrates, in a perspective view, a device according to the invention; Fig. 2 illustrates an enlarged view of the cup; Fig. 3 illustrates by hatching, a hydrophilic surface layer on the cup; and Fig. 4 illustrates the device in an exploded view;

Detailed description of the drawings

It should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Fig. 1 illustrates an obstetrical vacuum device 1 according to the invention. The device comprises a cup 2 forming a chamber 3 and being attachable to a fetal scalp by negative pressure in the chamber. The device comprises a pump 4 connected to the cup 2 via a tube 5. The pump can establish negative pressure in the cup when the handle 6 is moved towards the housing 7 by hand.

In use, the cup 2 is inserted into the birth canal and attached to the fetal scalp by use of vacuum obtained via the pump. Subsequently, the pump 4 is used as a grip by which the child can be pulled out of the birth canal. For ensuring connection between the handle shaped pump and the cup and thereby for preventing release of the cup when the child is pulled out of the birth canal, the tube 5 includes a wire, not visible in Fig. 1. The wire may particularly be integrated in the tube 5, but it could also be a separate part, e.g. outside the tube. The pump is manually operated by movement of the handle 6 relative to the grip which is formed by the housing 7.

In use, the surgeon, the midwife, or other trained staff, attaches the cup to the fetal head. By use of the pump, a negative pressure is created in the chamber until the cup is fixed to the head. Fig. 2 illustrates an enlarged view of the cup 2, and particularly, it illustrates that the outer surface 8 comprises a first surface portion 9 separated from a second surface portion 10 by a step formed by the third surface portion 11. The first and second surface portions are parallel and the third surface portion is intersecting the first and second surface portions.

The tube 5 exits the cup through the outer surface, and particularly through the third surface portion thereof.

Fig. 3 illustrates with cross-hatching, an area of the cup which is coated with a hydrophilic coating. The coated area includes the second surface portion but excludes the first and third surface portions. Particularly, it is an advantage not to coat the third surface portion.

The continuous surface pattern in the form of a circular depression 12 provides a tactile indication of the distance to the edge and it may further prevent adherence of the outer surface of the cup to the inner surface of the birth canal.

The hydrophilic coating could e.g. be from the company Argon Medical Devices Inc, e.g. the product named "Top Coat" and having product number 61869A and having the below mentioned ingredients, c.f. table no. 1 Ingredient GA8 # WL % Benzyl alcohol 100-51 -6 15 - 40 Et anol 64-17-5 15 - 40 Isopropanol 67-63-0' 10 - 30

Cyclohexanone 108-94-1 1 - 5 Polyethylene glycol 25322-68-3 1 - 5 Methyl alcohol 67-56-1 0 5 - 1 5 Methyl isobutyl ketone 108-10-1 0.5 - 1 .5 Ethyl Acetate 141 -78-6 0,5 - 15

Table 1, content in hydrophilic coating.

Numbered embodiments:

1. An obstetrical vacuum device (1) comprising a cup (2) forming a chamber with an opening and a sealing flange along the opening for establishing sealing contact with a fetal scalp, the device further comprising a pump (4) for establishing a pressure difference between an internal pressure in the chamber (3) and an external pressure in an ambient space, where the cup has an inner surface towards the chamber and an outer surface facing away from the chamber, characterised in that the outer surface comprises at least one hydrophilic surface portion.

2. A device according to embodiment 1, where the outer surface comprises at least one non- hydrophilic surface portion.

3. A device according to embodiment 1 or 2, where the hydrophilic surface portion(s) covers in the range of 25-75 percent of the outer surface.

4. A device according to any of the preceding embodiments, where the hydrophilic surface portion(s) cover(s) a part of the outer surface which is curved with a radius less than 10 mm.

5. A device according to any of the preceding embodiments, where the outer surface has a stepped configuration including at least one step separating a first distinct surface portion from a second distinct surface portion, the first surface portion being a hydrophilic surface portion and the second surface portion being non-hydrophilic.

6. A device according to any of the preceding embodiments, where the sealing flange is non- hydrophilic.

7. A device according to any of the preceding embodiments, where at least one of the hydrophilic surface portions is constituted by a hydrophilic surface coating. 8. A device according to any of the preceding embodiments, where the pump is connected to the cup via a tube, at least a portion of the tube having a hydrophilic surface.

9. A device according to any of the preceding embodiments, wherein at least one of the hydrophilic surface portions has a texture being different from the texture of at least one of the non-hydrophilic surface portions.

10. A method of operating an obstetrical vacuum device according to any of embodiments 1- 8, the method comprising the step of wetting at least one of the hydrophilic surface portions prior to insertion of the cup into a patient.

Numbered alternative embodiments:

Alternatively, the invention may relate to the following alternative embodiments:

1. An obstetrical vacuum device (1) comprising a cup (2) forming a chamber with an opening, and a sealing flange along the opening for establishing sealing contact with a fetal scalp, the device further comprising a pump (4) for establishing a pressure difference between an internal pressure in the chamber (3) and an external pressure in an ambient space, where the cup has an inner surface towards the chamber and an outer surface facing away from the chamber, characterised in that the outer surface has a stepped configuration.

2. A device according to alternative embodiment 1, where the stepped configuration provides a first surface portion of the outer surface at a first perpendicular distance over the sealing flange and a second surface portion of the outer surface at a second perpendicular distance over the sealing flange, the second perpendicular distance being larger than the first perpendicular distance.

3. A device according to alternative embodiment 2, where the first and second portions are plane and parallel to each other.

4. A device according to any of the alternative embodiments 2-3, where the sealing flange defines a sealing plane and where at least one of the first and second surface portions is parallel with the sealing plane.

5. A device according to any of alternative embodiments 2-4, where the first perpendicular distance is larger than the difference between the second and first perpendicular distances. 6. A device according to any of the preceding alternative embodiments, where the stepped configuration is formed by a third surface portion of the outer surface, the third surface portion connecting the first and second surface portions and not being perpendicular to the first and second surface portions. 7. A device according to any of the preceding alternative embodiments, where at least a portion of the outer surface is hydrophilic.

8. A device according to alternative embodiment 6 and 7, where the third surface portion is not hydrophilic.

9. A device according to any of alternative embodiments 6-8, where the third portion extends at an angle between 75-105 degrees to one of the first and second surface portions.

10. A device according to any of the alternative embodiments 2-9, where the pump is connected to the cup by a hollow tube, the tube extending through the outer surface outside the first and second surface portions.

11. A device according to any of alternative embodiments 6-9 and 10, where the tube extends through the third surface portion.

12. A device according to any of alternative embodiments 6-9 and 10-11, where the tube extends through the outer surface at an angle different from 90 degrees to the first and second surface portions.

13. A device according to any of alternative embodiments 6-12, where third surface portion has a texture different from the texture of the first and second portions.

14. A device according to any of alternative embodiments 2-13, comprising a continuous surface pattern extending into both the first and the second surface portion.

15. A method of operating an obstetrical vacuum device according to any of alternative embodiments 1-14, the method comprising the step of inserting the cup into a birth canal and attaching it to a fetal scalp while manipulating the cup by contact between fingers and the stepped outer surface.

Claims

2. A device according to claim 1, where the outer surface comprises at least one non- hydrophilic surface portion.

3. A device according to claim 1 or 2, where the hydrophilic surface portion(s) covers in the range of 25-75 percent of the outer surface.

4. A device according to any of the preceding claims, where the hydrophilic surface portion(s) cover(s) a part of the outer surface which is curved with a radius less than 10 mm.

5. A device according to any of the preceding claims, where the outer surface has a stepped configuration including at least one step separating a first distinct surface portion from a second distinct surface portion, the first surface portion being a hydrophilic surface portion and the second surface portion being non-hydrophilic.

6. A device according to claim 5, where the first surface portion is at a first perpendicular distance over the sealing flange and the second surface portion is at a second perpendicular distance over the sealing flange, the second perpendicular distance being larger than the first perpendicular distance.

7. A device according to claim 5 or 6, where the first and second surface portions are plane and parallel to each other.

8. A device according to any of claims 5-7, where the sealing flange defines a sealing plane and where at least one of the first and second surface portions is parallel with the sealing plane.

9. A device according to any of claims 5-8, where the first perpendicular distance is larger than the difference between the second and first perpendicular distances.

10. A device according to any of claims 5-9, where the stepped configuration is formed by a third surface portion of the outer surface, the third surface portion connecting the first and second surface portions and not being perpendicular to the first and second surface portions.

11. A device according to claim 10, where the third surface portion is non-hydrophilic.

12. A device according to any of the preceding claims, where the sealing flange is non- hydrophilic.

13. A device according to any of the preceding claims, where at least one of the hydrophilic surface portions is constituted by a hydrophilic surface coating.

14. A device according to any of the preceding claims, where the pump is connected to the cup via a tube, at least a portion of the tube having a hydrophilic surface.

15. A device according to any of the preceding claims, wherein at least one of the hydrophilic surface portions has a texture being different from the texture of at least one of the non- hydrophilic surface portions.

16. A method of operating an obstetrical vacuum device according to any of claims 1-15, the method comprising the step of wetting at least one of the hydrophilic surface portions prior to insertion of the cup into a patient.