Abstract:
A vacuum extractor for obstetrical use comprises a vacuum cup at one end of an elongated stem having a handle at the opposite end. The vacuum cup is sealed over a portion of the head of the fetus and a vacuum source, usually operating through the stem, connects to the inner side of the cup and secures it to the fetal head. A strain sensor is connected to the stem. When the force applied to the cup through the handle and stem exceeds a predetermined maximum, a valve connecting the vacuum pressure to the atmosphere is opened so as to release the vacuum pressure from the cup. Another extractor comprises an elongated hollow stem having one or more apertures along its length, a vacuum source connected to a cup supported on the stem, and a handle member which includes a traction limiting element operative to open and close the apertures.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation in part of, and claims priority from, U.S. patent application Ser. No. 12/371,263, filed Feb. 13, 2009, now abandoned which in turn claims priority from U.S. Provisional Patent Application Ser. No. 61/028,243, filed Feb. 13, 2008, both of which are incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to an improved vacuum extractor for childbirth including a vacuum cup connected to a handle through a stem and more particularly to such an extractor including a traction gauge which measures the extraction force applied to the fetus through the cup and releases the vacuum on the cup when the extraction force exceeds a predetermined value. 
     BACKGROUND OF THE INVENTION 
     Vacuum extractors have long been used as a tool to assist delivery, primarily in vaginal deliveries. These extractors are often used when spontaneous vaginal delivery is not possible or is unsuccessful. They typically employ a bell shaped vacuum cup connected to a handle that is used to apply a tractive force to the cup with a tube being connected by an elongated stem. A manually or electrically powered suction device is attached to the cup either through a peripherally located vacuum port or through the stem. 
     In use, the surgeon attaches the open end of the vacuum cup over the fetal head. A vacuum is then drawn in the cup either through use of a manually operated vacuum pump or an electrical vacuum pump. The physician then pulls on the handle to apply a delivering force to the fetal head. The force applied to the extractor must be limited to prevent harm to the fetus. With conventional vacuum extractors reliance is placed on the physician&#39;s estimate of the force being applied to avoid the imposition of excessive forces. 
     It has been proposed to provide vacuum extractors incorporating sensors which measure the force applied between the vacuum cup and the handle to provide the physician with an indication of when excessive forces are being applied. 
     U.S. Pat. No. 6,355,047 discloses an extractor incorporating such a sensor and provides a slipping mechanism which causes the length of the force center to increase when an applied traction force exceeds a predetermined level. The physician may then use his judgment as to whether to continue to apply a greater force or to terminate use of the vacuum extractor. However, in some situations excessive force has been applied despite the incorporation of a force sensor and/or a slipping mechanism, resulting in the breaking of blood vessels connecting the fetal scalp from its underlying surface. 
     SUMMARY OF THE INVENTION 
     The present invention is accordingly directed toward an obstetrical vacuum extractor including a traction sensor connected to the air valve which releases the vacuum within the suction cup when an excessive, predetermined, force is applied to the handle of the extractor. The birthing attendant then may reattach the cup to the fetal scalp and reapply the vacuum, or resort to other means to complete the delivery. In a preferred embodiment of the invention, which will subsequently be disclosed in detail, the sensor includes a gauge operative to provide a visual indication to the user of the extraction force being exerted. The vacuum gauge may be incorporated in the conduit between the vacuum cup and the vacuum source, or alternatively it may be built into the stem, using a strain gauge or the like. 
     In another aspect of the invention there is provided a vacuum extractor for use by a physician in an obstetrical delivery where the extractor is in suction communication with a vacuum source. The extractor includes: an elongated hollow stem having one or more apertures along its length; an open-ended cup supported on one end of the stem with the open end directed away from the stem, the vacuum source connected to the interior of the cup so that when the one or more apertures are closed and the open end of the cup is brought into contact with the fetal scalp a vacuum secures the cup to the scalp; and a handle member disposed on the stein. The handle member includes: handle ears; and a traction limiting element in arrangement with the handle ears. The limiter is operative to open and close the one or more apertures. When no traction is applied by the physician to the handle ears the traction limiting element blocks air flow from the ambient atmosphere through the one or more apertures to the stem and when the physician applies traction to the handle ears so that the magnitude of the traction exceeds a predetermined value the traction limiting element is operative to open the one or more apertures allowing a flow of air from the ambient releasing the vacuum securing the cup to the fetal scalp. 
     In one embodiment of this second aspect of the invention, the handle ears of the vacuum extractor have a channel and a passage formed therein. The passage is in air flow communication via the channel with the one or more apertures of the elongated hollow stem. The traction limiting element includes: one or more pressure valves positioned in the passage disposed within one or more of the handle ears. The one or more pressure valves have a distal portion and a proximal portion, each portion having an internal diameter with the internal diameter of the distal portion being smaller than that of the proximal portion. The limiter also includes an elastic element circumscribing the one or more pressure valves, and when no traction is applied to the handle ears the proximal portion of each of the one or more pressure valves closes off the channel and the one or more apertures from the ambient. When the physician applies traction in excess of a predetermined magnitude to the handle ears, the one or more pressure valves move in a proximal direction causing the narrow distal portion of the pressure valves to move so as to become positioned adjacent to the channel thereby opening the channel and the one or more apertures of the stem to the ambient, thereby releasing the suction force on the scalp of the fetus. 
     In the above embodiment of the second aspect of the invention, the handle member of the vacuum extractor further includes a handle cover spaced apart from the handle ears on the distal side of the handle ears. When traction is applied by the physician the handle cover moves in the proximal direction narrowing the space between the handle cover and the handle ears thereby applying a force to the one or more pressure valves so that they move in the proximal direction. This allows the narrower distal portion of the one or more valves to move adjacent to the channel, opening it and the one or more apertures in the stem to air from the ambient. 
     In another embodiment of the second aspect of the present invention the traction limiting element of the vacuum extractor includes: a housing and a sealing element in arrangement with the housing. The sealing element is movably fitted on the stem of the extractor and seals off the one or more apertures from the ambient when positioned adjacent to the one or more apertures. When a physician applies traction to the handle member, the sealing element moves in the proximal direction past the one or more apertures and serially opens them to the ambient atmosphere, thereby releasing the vacuum being applied to the scalp of the fetus. 
     The traction limiting element of the vacuum extractor in this second embodiment of the second aspect of the invention may further include a spring element positioned on a spring base within the housing. The spring element is compressed under a traction force and when the traction force is released the spring element returns to its uncompressed state moving the sealing element in the distal direction to its original position again blocking ambient air from entering the one or more apertures. 
     The second aspect of the present invention also provides handle members and traction limiters constructed substantially as described above with respect to the traction limiting elements in the vacuum extractors of the second aspect of the invention described above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, advantages and applications of the present invention will be made apparent by the following detailed description of preferred embodiments of the invention. The description makes reference to the accompanying drawings in which: 
         FIG. 1  is a side view of an obstetrical vacuum extractor forming a first embodiment of the invention; 
         FIG. 2  is a breakaway section through the stern of the extractor of  FIG. 1  illustrating the pressure sensor and the relief valve controlled by the pressure sensor; 
         FIG. 3  is a partial side view of a second embodiment of the invention wherein the digital pressure sensor and a relief valve controlled by the detection of excess pressure by the sensor are located in the vacuum line to the extractor body; 
         FIGS. 4A and 4B  are a cut away side view and a regular side view of a first embodiment of a second aspect of the present invention; 
         FIG. 5A  is a side view of a second embodiment of the second aspect of the present invention; 
         FIG. 5B  is a partial cutaway side view of the handle region of the extractor shown in  FIG. 5A ; 
         FIG. 5C  is another less detailed cutaway side view of the handle and pressure valve of the embodiment shown in  FIG. 5A ; 
         FIG. 5D  is a cross section of the handle cover in the embodiment of  FIGS. 5A-5C ; 
         FIGS. 6A-6B  illustrate a third embodiment of the second aspect of the present invention, the embodiment having collapsible or bendable handles; 
         FIG. 7A  is a cutaway side view of a fourth embodiment of the second aspect of the present invention; and 
         FIG. 7B  is a perspective view of a force load sensing element used in the embodiment shown in  FIG. 7A . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings,  FIG. 1  illustrates a preferred embodiment of my invention constructed on an obstetrical vacuum extractor of the general type illustrated in U.S. Pat. No. 5,019,086. The extractor, generally indicated at  10 , has an elongated hollow stem  12 , preferably formed of plastic. The lower end of the stem, as illustrated in  FIG. 1 , is connected to a resilient cup  14  which is open at its lower end  16 . The cup is formed as a shell and the interior of the cup  14  communicates with the hollow section of the stem  12 . 
     In alternate embodiments of the invention the cup  14  can be rigid and made of metal, although resilient cups are more popular with obstetricians. 
     The upper end of the stern  12  is connected to a rigid handle  18  consisting of two ears  20  which project on opposite sides of the connection of the handle to the stem. The upper end of the hollow within the stem is joined to a connector  22  which is adapted to receive a flexible vacuum hose (not shown). A plurality of ribs  24  formed along the length of the connector  22  provides an airtight seal for the connecting air hose. 
     In use, the open end  16  of the cup  14  is brought into contact with the fetal scalp and a vacuum source is joined to the connector  22 . The vacuum source may be mechanically actuated with a pump powered by an assistant, or it may take the form of an electrically powered vacuum device. The suction force from the vacuum device is communicated through the stem  12  to the cup  14  and draws a vacuum which securely retains the open end  16  of the cup in contact with the fetal scalp. The physician then grasps the handle  18  and pulls on the extractor to exert a force on the fetus which assists in the delivery of the fetus through the vagina. 
     The vacuum extractor  10  differs from conventional vacuum extractors in two respects: First, an analog gauge  26  is positioned on the stem  12  and connected so as to sense the force applied to the fetal scalp by manipulation of the device  10 . That value is exhibited on the face of the gauge  26 . Secondly, a relief conduit  28  is positioned on the body of the stem so as to connect the interior of the stem, and thus the active area of the cup  16 , to atmospheric pressure under certain conditions. 
     Referring to  FIG. 2 , which is a partial cross section through the extractor  10 , taken along lines  2 - 2  of  FIG. 1 , the stem has an interior hollow  32  which communicates the vacuum from the connector  22  to the fetal scalp through the open end  16  of the cup  14 . The vacuum drawn on the scalp passes through the gauge  34 , connected to the dial  26 . The gauge  34  also generates an electrical signal on output lines  36  when a predetermined value of vacuum, which represents the maximum safe extraction pressure, is exerted. The gauge is preferably battery powered. The lines  36  connect to a valve  38  which connects to the atmosphere through the conduit  28 . Thus, when the pressure sensed by the gauge  34  exceeds the predetermined maximum value, the vacuum is connected directly to the atmosphere, relieving the vacuum pressure between the cup  14  and the fetal scalp. 
     In other embodiments of the invention the gauge  26  could present a digital output and/or the trigger value at which the gauge sends a signal to the valve  38  could be adjusted. 
     A second embodiment of the invention is illustrated in  FIG. 3 . The handle end of a vacuum extractor is generally indicated at  40 . The vacuum extractor  40  may be identical to the vacuum extractor  10  and to the prior art in that it does not include a gauge  26  or a relief conduit  26 ; alternatively, in this embodiment of the invention those units are incorporated in the line connecting the vacuum extractor to the vacuum source. 
     As illustrated in  FIG. 3 , the handle  18  of the vacuum extractor  40  is equipped with a vacuum inlet port at connector  22  of the same type as illustrated on the extractor  10  of  FIGS. 1 and 2 . A vacuum source  42 , preferably electrically powered, draws a vacuum through a line which is joined to the connector  22  by a female tubular connector  44  which slides over the male connector  22 . Also connected in the line  46  is a digital gauge  48 , which is preferably adjustable to a predetermined limit decided on by the attending physician, and a relief valve  50  connected to the gauge by line  52 . When the limit set on the gauge  48  is reached, a signal is sent to the valve  50  which connects the line  46  to the atmosphere and thus relieves the vacuum on the cup  14  attached to the fetal scalp. The system operates in just the same way as the extractor  10  of  FIG. 1 , but incorporation of the gauge  48  in the valve  50  and the input line  46  allows the invention to be used with a conventional extractor which does not have its own pressure gauge and relief line. 
     A vacuum extractor, generally indicated as  100 , has an elongated hollow stem  112 , preferably formed of plastic. The end of stem  112  closest to the distal end (D) of extractor  100 , is connected to a resilient cup  114  which is open at its distal end  116 . Cup  114  is formed as a shell and the interior of the cup communicates with the hollow section of stem  112 . Alternatively, cup  114  can be rigid and made of metal, although resilient cups are more popular with obstetricians. 
     A rigid handle  118 , comprised of two ears  120 , projects from opposite sides of handle housing  158 . Housing  158  connects handle  118  to stem  112  at a position distant from cup  114  and in a proximal direction therefrom. 
     Handle  118 , having handle ears  120 , is typically integrally formed with handle housing  158  and movably attached to stem  112 . Press spring  140  is positioned on spring base  146  within handle housing  158 . Spring base  146  is substantially annular-shaped and either may be formed as an integral part of stem  112  or as a separate part fixedly attached to stem  112 . 
     While we have denoted element  140  as a press spring, any other elastic element capable of performing the functions of press spring  140  as described herein may also be used. Typically, but without intending to limit the invention, spring  140  may be formed of metal, but other materials having the required performance characteristics may also be used. Other elastic elements which may be used include elements formed from metals or plastics or other suitable elastomeric materials known to those skilled in the art. 
     Handle housing  158  is positioned on stem  112  at a position adjacent to apertures  152 ,  154  and  156 , the apertures disposed in stem  112 . When vacuum extractor  100 , herein also referred to as device or vacuum extractor device or extractor device  100 , is not being used, aperture sealing element  159 , an integral part of handle housing  158 , lies adjacent to apertures  152  and  154  hermetically sealing them and not allowing air from the ambient to enter the hollow  170  of stem  112 . When device  100  is not in use, or when the mother is between contractions during the later stages of the birth, aperture  156  is kept open. Aperture sealing element  159  also functions as that portion of housing  158  directly connecting housing  158  to stein  112 . 
     The volume created by handle housing  158  contains press spring  140  and handle housing  158  is open to the ambient at its proximal end near spring base  146 . 
     Flexible tube  122  is force fitted onto proximal end  142  of stem  112 . Proximal end  142  of stem  112  may be formed to contain ratchet-like grooves for a better fit with flexible tube  122 . Flexible tube  122  is attached to a vacuum suction source (not shown) at its proximal end (also not shown). 
     It should be evident to persons skilled in the art that other techniques may also be used to connect tube  122  to stem  112 . For example, as in the embodiment of the present invention discussed in conjunction with  FIGS. 1-3  above, the proximal end of hollow  170  within stem  112  may be joined to a connector (not shown) which is adapted to receive a flexible tube  122 . A plurality of ribs (discussed in conjunction with  FIGS. 1 and 3 ) formed along the length of the connector  22  ( FIGS. 1 and 3 ) provides an airtight seal for connecting flexible tube  122  to stem  112 . 
     Vacuum extractor  100  differs from conventional vacuum extractors in several respects. Handle housing  158  rides on press spring  140  and when a user pulls on handle  118 , the user exerts a traction force on the fetus in an attempt to accelerate its passage through the birth canal. When traction is exerted, press spring  140  is compressed and handle housing  158  moves in the proximal direction. As housing  158  moves proximally, aperture sealing element  159  first moves proximally covering previously open aperture  156  in addition to covered apertures  152  and  154 . When all three apertures are covered, suction provided by a vacuum suction source (not shown) can attain a maximal value. As the traction force exerted by the physician on the handle of device  100  slowly increases and reaches a predetermined value, sealing element  159  sequentially passes apertures  152  and  154  in tube  112  allowing them to open and the suction being applied to the fetus via cup  114  to be progressively released. Opening aperture  152  partially releases the suction on the scalp of the fetus; when sealing element  159  moves further in the proximal direction aperture  154  opens and the suction is entirely released. As noted above, movement of aperture sealing element  159  is a function of the traction exerted by the physician. Therefore, handle housing  158  and aperture sealing element  159  function as a traction limiter in the fetal extraction process. 
     Optionally, an indicator strip  148  is positioned on stem  112  at least partially underneath handle housing  158 . Strip  148  appears and becomes progressively larger as handle housing  158  moves progressively along stem  112  in the proximal direction. As traction increases, indicator strip  148  provides the user with a qualitative indication of how much traction force is being applied. It should readily be understood by persons skilled in the art that the indicator can be calibrated against specific predetermined traction forces so that a more quantitative value for the traction force actually being applied may be obtained. 
     When in use, the open distal end  116  of cup  114  is brought into contact with the fetal scalp and a vacuum source (not shown) is joined to flexible tube  122  which in turn is in suction communication with stem  112  and cup  114 . The vacuum source may be mechanically actuated with a pump powered by an assistant, or it may take the form of an electrically powered vacuum device. Other types of vacuum sources may also be used. 
     The suction force from the vacuum source is communicated through flexible tube  122  to hollow  170  of stem  112  and from there to cup  114 . The vacuum securely retains the open end  116  of cup  114  in contact with the fetal scalp. The physician then grasps and pulls on the two ears  120  of handle  118  in the proximal direction (P) to exert a force on the fetus which assists in the delivery of the fetus through the vagina. 
     Reference is now made to  FIGS. 5A-5D , where several different views of a second embodiment of the second aspect of the invention are presented. 
     In  FIG. 5A  a slightly off-angle side view of a vacuum extractor device, generally referred to as  200 , is shown. Extractor  200  has an elongated hollow stem  212 , preferably, but not necessarily, formed of plastic. The end of stem  212  closest to the distal end (D) of extractor  200  is connected to a resilient cup  214  which is open at its distal end  216 . Cup  214  is formed as a shell and the interior of the cup communicates with the hollow  270  ( FIG. 5B ) of stem  212 . An optional indicator strip  248  is shown as is handle  218 . A flexible tube  222  force fitted over the proximal end  242  ( FIG. 5B ) of stein  212  also appears in the Figure. This proximal end  242  of stem  212 , best seen in  FIG. 5B , may have ratchet-like grooves for a better fit with the distal end of flexible tube  222 . Handle  218  has a handle cover  262  which is spaced apart from handle  218  by space  263  ( FIG. 5B ).  FIG. 5D  is a transverse cross-section of handle cover  262 . 
     Referring now to  FIGS. 5B and 5C , suction from a vacuum source (not shown) is brought to cup  214  via flexible tube  222  and stem  212  and is applied to the scalp of a fetus. When a user applies traction to device  200 , the hand of the user presses on handle cover  262 . This traction causes cover  262  to move in the proximal direction (P) so that it compresses press spring  240 . Press valve  260  is fixedly connected with handle cover  262 , the connection being effected by any of many different methods known in the art. Press valve  260  may be made of plastics or metal, for example, but without attempting to limit the invention, acrylonitrile/butadiene/styrene (ABS) or stainless steel. Methods for fixedly connecting handle cover  262  to press valve  260  may be gluing, ultrasonic welding, injection or insertion molding or any other suitable method. As handle cover  262  is pressed moving in the proximal direction, it compresses press spring  240  and presses on press valve  260  causing it to move in the proximal direction. 
     Press valve  260  is comprised of a smaller diameter part  264 , a larger diameter part  268 , and a lock portion  267 . The larger diameter part  268  is substantially equal to the diameter of an air passage  265  in which press valve  260  is positioned. Large diameter part  268  is sized to substantially close the entrance of an air channel  266  at its juncture with air passage  265 . As handle cover  262  presses press spring  240  and concomitantly as press valve  260  moves in the proximal direction, the large diameter part  268  of valve  260  moves past air channel  266  and is replaced by Smaller diameter part  264  at the entrance of air channel  266 . This allows air from the ambient entering via handle space  263  and air passage  265  to enter air channel  266 . The opening of channel  266  occurs at a predetermined traction force value. As air from channel  266  enters hollow  270  of stem  212 , suction is immediately released and cup  214  detaches from the head of the fetus. 
     When the traction force is released, handle  218  moves in the distal direction returning to its original position. Press valve  260  and press spring  240  will also return to their original positions by moving in the distal direction. Handle cover  262  also moves in the distal direction returning to its original position and lock part  267  of press valve  260  helps keep handle cover  262  from separating from press valve  260 . 
     Press valve  260  and press spring  240  as described above function as a traction limiter in the fetal extraction process. 
     Typically, but without intending to limit the invention, press spring  240  may be formed of metal but other materials having similar performance characteristics may also be used. Elastic elements capable of performing the functions of press spring  240  as described herein may also be used. Such elements may be formed from metals, plastics or elastomers having performance characteristics similar to those of press spring  240 . 
     Optionally, as in the previous embodiment, an indicator strip  248  ( FIG. 5A ) is positioned on stem  212 , at least partially underneath handle cover  262 . Strip  248  becomes progressively larger as handle cover  262  moves progressively along stein  212  in the proximal direction when cover  262  is pressed. As traction increases, indicator strip  248  provides the user with a qualitative indication of how much traction force is being applied. It should readily be understood by persons skilled in the art that the indicator can be calibrated against specific predetermined traction forces so that a more quantitative value for the traction force actually being applied may be obtained. 
       FIGS. 5B and 5C  show two different partial side views of handle  218  and/or handle cover  262 . Both sides of handle  218  are not shown. However, it should be readily understood that handle  218  may be symmetrical on both sides of stem  212  with a press valve  260 , an air passage  265  and an air channel  266  present on both sides of stem  212 . Alternatively, the valve on the second side (not shown) of handle  218  may be a dummy valve with no air channel  266  connection to hollow  270  of stem  212 . Alternatively, there may be no valve, real or dummy, on the second side (not shown) of handle  218 . 
     Most of the elements in the embodiments discussed in conjunction with  FIGS. 4A-5B  are made of plastic. For example, but without limiting the types of plastic which may be used, stem  112 ,  212  and cup  114 ,  214  may be made from high density polyethylene (HDPE), handles  118 ,  218 , press valve  260  and handle cover  262  may be made from acrylonitile/butadiene/styrene (ABS), and flexible tube  122 ,  222  may be made from silicone, polyvinyl chloride (PVC) or polyurethane (PU). Springs  140  and  240  may be made of stainless steel. 
     In a third embodiment of the second aspect of the invention, shown in  FIGS. 6A and 6B , a vacuum extractor similar to the one shown in  FIG. 4B  and discussed above is presented. With the exception of handle  130  and handle ears  138 , all parts in  FIGS. 6A and 6B  are the same as those in  FIG. 4B . Accordingly, the construction and operation of those parts will not be discussed again. Handle  130  and handle ears  138  may be formed from a suitable plastic of the required mechanical strength and configured so that ears  138  collapse or severely bend when a predetermined traction force is reached. This would indicate that the vacuum source (not shown) must be immediately disconnected. A typical but none limiting configuration for the handle is presented in  FIG. 6A . Here, handle ears  138  of handle  130  are configured to bend or collapse as a result of the narrow constrictions in the region where handle ears  138  join handle housing  158 . It should be readily evident to persons skilled in the art that the use of collapsibly configured handle ears  138 , similar to those shown in  FIGS. 6A and 6B , may be used with many other types of vacuum extractors as a means for indicating that excess traction force is being applied and should be limited. These collapsible configurations need not be used solely with the embodiments shown in  FIGS. 4A-5B . 
     In a fourth embodiment of the second aspect of the invention, shown in  FIGS. 7A and 7B , a vacuum extractor  100  similar to the one shown in  FIG. 4A , and discussed above is presented. With the exception of a load sensing element  180 , shown in  FIG. 7B  separately and in  FIG. 7A  as part of vacuum extractor  100 , all parts in  FIG. 7A  are the same as those in  FIG. 4A . Accordingly, the construction and operation of those parts will not be discussed again. 
     As seen in  FIG. 7B , electrical force load sensing element  180  comprises an annular ring member  186  and electrical wires  182 , the latter connected to an electrical connector  184 . Electrical connector  184  may be connected to an alarm element (not shown), such as a buzzer, or the vacuum source (also not shown) or both. The electronic signal of load sensing element  180  or the circuit to which it is connected, may be activated, at a predetermined over-traction force, to buzz noisily, or to release the vacuum in the vacuum source, or to do both. 
       FIG. 7A  shows the integration of force load sensing element  180  into vacuum extractor  100 . Force load sensing element  180  is positioned on spring base  146 . As press spring  140  becomes more and more compressed under traction, the load in load sensing element  180  increases. At a predetermined value of traction force, that is reflected in the degree of press spring  140  compression, an alarm system, such as a buzzer, is activated alerting the physician to deactivate the vacuum source or the vacuum source itself is automatically electronically deactivated using suitable electronics. The required electronic circuitry may readily be constructed and configured by persons skilled in the art. 
     Typically, the over-traction forces which cause the exposure of aperture  152  and then aperture  154  of  FIGS. 4A-4B  may be 17 and 18 kgs respectively and the over-traction force that causes air to flow through the air channel(s)  266  of  FIG. 5B  is 18-20 kgs with a 6 cm cup diameter and 14 kgs with a 5 cup diameter. These are over-traction forces that can be used with embodiments employing the bendible/collapsible handle ears of  FIGS. 6A-6B . Open aperture  156  of  FIGS. 4A-4B  is, as noted above, the default position before full suction is applied to the fetal scalp and before the physician applies traction to handle  118 . Aperture  156  is also kept open between contractions during the birthing process when it lowers the suction on the fetal scalp from about 600 mm Hg to about 500 mm Hg. However, it should be readily evident to persons skilled in the art that these over traction values and cup sizes can be modified as desired subject to the physiological and anatomical constraints of the fetus and mother. 
     Where the terms “physician” and “user” are used herein it should readily be understood that these terms may include any birthing attendant that would have occasion to use a vacuum extractor during a birth. 
     It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.