Surgery – Instruments – Obstetric or gynecological instruments
Reexamination Certificate
2001-10-24
2002-07-30
Philogene, Pedro (Department: 3732)
Surgery
Instruments
Obstetric or gynecological instruments
C606S119000, C606S205000
Reexamination Certificate
active
06425899
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an obstetric forceps for grasping a baby during childbirth, which forceps have blades which are approximately adapted to the shape of a baby's head, are made of a rigid material and have contact surfaces for grasping the baby's head, which contact surfaces are provided with at least one device for detecting the pressure prevailing between the contact surface and the baby's head.
STATE OF THE ART
Obstetric forceps for grasping a baby during childbirth are common knowledge. Obstetric forceps are partly made of metal and comprise two forceps elements moveably connected by means of a joint, also referred to as a catch. State of the art forceps have a handle section and a grasping section which are separated by the joint. Forceps blades adapted to the shape of a baby's head are provided at the grasping section with which the baby's head can be grasped by exactly fitting around the head respectively at least partially surrounding the head. The handle section is provided with handles for operating the forceps. At the section leading to the joint of each handle, there is a laterally projecting extraction hook which is employed to extract the child grasped by the forceps out of the mother's body.
However, occasionally in so-called forceps births there is injury to the baby's head ranging from nerve damage to impression fractures of the skull caused by too much pressure applied by the forceps on the baby's head during delivery. The pressure acting on the baby's head cannot be controlled by means of known methods and devices. Thus, the pressure is solely controlled by the sensitivity of the fingers of the obstetrician operating the forceps. This can lead to problems particularly if the obstetrician is strong or inexperienced, because too much pressing force may be applied to the baby's head with such forceps.
Moreover, frequently the obstetric forceps touches the head only at certain points as the shape of a baby's head varies strongly and sometimes there are great radii of curvature. Therefore, the obstetric forceps does not always fit exactly around the baby's head. Thus, the force applied at the forceps handle may apply quite varying point pressures to the baby's head depending on to what degree the shape of the baby's head concurs with the shape of the forceps. If the forceps touches only a few, small points, more pressure is applied than if the forceps touches the baby's head at several points distributed over a large area.
In order to significantly reduce such head injuries to babies delivered with forceps, U.S. Pat. No. 2,637,230 describes an obstetric forceps in which the blades of the forceps are surrounded by an expandable, elastic volume that can be filled with compressed air and widened to largely surround the baby's head fitting snugly without coming into direct contact with the, usually metal, blades of the forceps.
However, the known obstetric forceps do not allow the physician to determine whether the presently applied pressing force between the forceps blades and the baby's head exceeds a predetermined maximum load. A remedy is the obstetric forceps of US printed publication U.S. Pat. No. 3,785,381 which is provided with a pressure sensor at the insides of the forceps blades facing the baby's head. This sensor indicates to the physician the currently prevailing pressing force at the site of the pressure-measuring sensor via a corresponding display device.
However, the known obstetric forceps provided with such pressure sensors have the drawback that the area where the pressure is measured is very restricted locally so that the physician is unable to prevent excessive pressure which may occur due to the blades of the forceps at sites not provided with pressure-measuring sensors.
DE 42 35 442 A1 describes an obstetric forceps whose blades are provided with a covering surrounding a cavity. This covering is fillable with a liquid or gaseous medium. The covering, which is preferably made of an expandable, elastic material, serves as a buffer cushion when the head is grasped and helps prevent local pressure peaks on the baby's head as far as possible. Moreover, a pressure sensor connected with the medium to which the pressure is applied permits determining the surface pressure between the obstetric forceps and the baby's head. However, this mode does not permit site-resolved detection of locally occurring pressure peaks.
DESCRIPTION OF THE INVENTION
The object of the present invention is to improve an obstetric forceps for grasping a baby's head during delivery, which forceps have blades, which are approximately adapted to the shape of a baby's head, are made of a rigid material and have contact surfaces for grasping the baby's head, which contact surfaces are provided with at least one device for detecting the pressure prevailing between the contact surface and the baby's head, in such a manner that an injury to the baby's head due to excessive local pressure is largely ruled out. It should, in particular, be possible for the physician to gently grasp the baby's head over a large surface and determine information, preferably site-resolved, about any possible excessive pressure that may occur over the entire contact area between the obstetric forceps and the baby's head.
The solution to the object of the present invention is set forth in claim 1. Advantageous further-developing features of the inventive idea are the subject matter of the subclaims and are described in the accompanying drawings with respective descriptions.
The invented obstetric forceps for grasping a baby during childbirth, which forceps have blades which are approximately adapted to the shape of a baby's head, are made of a rigid material and have contact surfaces for grasping the baby's head, which contact surfaces are provided with at least one device for detecting the pressure prevailing between the contact surface and the baby's head, is distinguished by the contact surfaces of the blades of the forceps being provided with an elongated, elastically ductile contact body and by the pressure detecting device being designed in such a manner that the contact body has, at least at the side facing the contact surface, an electrically-conductive surface as well as by electrodes, which are insulated from each other, being provided at the contact surfaces of the obstetric forceps. These electrodes are contactable with the contact body when the latter deforms in such a manner that with increasing deformation of the contact body, an increasing number of electrodes are interconnected by the electrically conductive surface of the contact body.
In this way, it can be prevented that the forceps presses the baby's head with so much force when the baby's head is grasped with the invented forceps that more pressure is applied at any locally confined point than the predetermined maximum pressure. The maximum pressure is set in such a manner that it is ensured that no injury to the baby's head can occur.
According to a preferred embodiment of the invented obstetric forceps, the contact body is made of a viscoplastic material and has a rounded cross section so that when pressure is applied on the contact body, the surface where the contact surfaces of the forceps blades touch the contact body is enlarged.
The contact bodies are preferably made of an electrically conductive material, at least in region of their surface area. The pressure detection device is provided with multiple electrodes that are electrically insulated from one another and run parallel in the longitudinal direction of the blades of the forceps. Upon deformation of the contact body, these electrodes are contactable with the contact body.
The invented preferred embodiment of the obstetric forceps is simple to realize and it can be determined with certainty if the maximum pressure has been reached at any locally confined deformation of the contact b
Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung
Philogene Pedro
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