WO2003009766A1

WO2003009766A1 - Obstetrical vacuum extractor cup with vacuum generator, and vacuum generator

Info

Publication number: WO2003009766A1
Application number: PCT/US2002/023666
Authority: WO
Inventors: James E. Moore, Jr.; Phillip Clay Brown; Jeff Wright
Original assignee: Prism Enterprises, L.P.
Priority date: 2001-07-26
Filing date: 2002-07-25
Publication date: 2003-02-06

Abstract

The invention provides a medical device, in particular, an obste trical vacuum cup assembly coupled to a hand-held, venturi-propagated vacuum generator, such that the assembly or device may be maneuvred and a vacuum applied by a single hand of the physician. A canister or cartridge of compressed gas, such as carbon dioxide (CO2), or pressurized air flow typically available in hospitals is fluidly coupled for selective activation to the input of the venturi mechanism, while the output of the venturi mechanism is vented to the atmosphere. The hollow interior of the device is fluidly coupled to the throat of the venturi such that the flow of gas released from the charged canister or the pressurized air supply through the venturi mechanism results in the establishment of a vacuum within the device. The invention further provides a self-contained, hand-held vacuum-generating device utilizing a canister or cartridge of compressed gas and methods of utilizing the same.

Description

OBSTETRICAL VACUUM EXTRACTOR CUP WITH VACUUM GENERATOR, AND VACUUM GENERATOR

FIELD OF THE INVENTION

[0001] The present invention relates to an apparatus for facilitating the delivery of a child during childbirth, and more specifically relates to a combination vacuum extractor and vacuum generator for use during childbirth.

BACKGROUND OF THE INVENTION

[0002] During childbirth, the birth mother is sometimes unable to deliver the child without assistance. In some cases, all that is required is for a nurse, midwife, or attending physician to push down on the birth mother's upper abdomen when she bears down during delivery. In other cases, it is necessary for a physician to perform a Caesarean section. For those cases between the two extremes, some sort of intermediate assistance is often required. Such intermediate assistance generally entails the use of a device to aid in the delivery ofthe child. These devices may likewise be required to assist a physician during particularly difficult Caesarean sections.

[0003] 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 the mother and infant and risks injury to both.

[0004] Alternative devices to forceps are obstetrical vacuum extractors. Conventional obstetrical vacuum extractor systems utilize a cup, which may be placed onto the child's 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 a hand-held pump. Operation ofthe hand-held pump results in the development of a vacuum between the cup and the infant's head, which is then used to maneuver and extract the infant from the birth canal by pulling in an appropriate direction on the gripping device. The tube may be coupled directly to the cup or coupled to an elongated hollow stem which acts as the tractioning device. Other tractioning devices may be in the form of a cord, a chain, or the like disposed within or separate from a vacuum tube. The gripping device may be in the form of a handle, or a loop in a cord or the like.

[0005] More recently, unitary obstetrical vacuum extractor devices have been developed that include a vacuum extractor cup integrated with a hand-held pump and pulling handle. In this way, once properly placed on the infant's head, the physician can both apply an extraction force and maneuver 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 5,395,379 to Deutchman et al., and U.S. Patents 6,074,399 and 6,059,795 to Wallace et al.

[0006] Devices constructed in accordance with both the Deutchman and Wallace patents require the physician to make a repetitive pumping or squeezing action with the hand in order to draw a vacuum within the cup. The physician may be required to squeeze the pump handle literally dozens of times before the optimal vacuum pressure for exerting an extraction force is obtained, resulting in an undue delay between the time that the vacuum is needed and the time that the vacuum is actually developed. Additionally, over the course of delivery, this frequent squeezing action may result in discomfort or fatigue in the physician's hand and arm. Inasmuch as leakage can occur between the basal opening ofthe cup and the infant's head, the physician is frequently required to continue to perform the pumping action while exerting an extraction force in order to maintain an adequate vacuum force for extraction. Under these circumstances, repeatedly squeezing the pump while exerting an extraction force and maneuvering the cup can be particularly cumbersome and uncomfortable. Additionally, the handle assemblies ofthe Deutchman and Wallace devices are both considerably more bulky than traditional vacuum cup assembly handles due to the shear size ofthe pump mechanism contained in the handle. This increase in the bulk ofthe vacuum cup assembly handle can make the devices cumbersome to use in the close spaces typical during childbirth.

[0007] During use, it is imperative that the physician be provided with an accurate monitor ofthe forces exerted on the infant's head. In this regard, it is critical that the physician be aware ofthe level of vacuum pressure applied to the infant's head, to ensure that adequate vacuum pressure is maintained both to permit the application of a traction force and to minimize the possibility of injury to either the infant or the mother. Moreover, while they both provide for monitoring ofthe pressure level, the visibility of the pressure gauge disclosed in the Deutchman and Wallace devices may be limited in that they are disposed along one side ofthe assembly. While the commercial embodiment ofthe Wallace device includes a slidably mounted pressure gauge which telescopes from one end ofthe handle, the telescoping pressure gauge is relatively sharp and may cause damage to surrounding maternal tissue. Further, the telescoping gauge may be readily damaged as the relatively long, yet small cross-section gauge cantilevers from the end ofthe handle as vacuum extraction pressure is developed and in a static position.

[0008] It is also helpful to the physician to monitor the length of time, for example, of labor itself, between contractions, or for which a vacuum is applied. Unfortunately, neither the Deutchman device nor the Wallace device themselves provide the physician with direct feedback regarding the passage of time.

[0009] Additionally, mechanical hand pumps, including those utilized with, as in U.S. Patents 4,775,302, 4,806,084, and 4,954,054, or as apart of an obstetrical vacuum extractor, as in Deutchman and Wallace, for example, comprise a number of moving parts. The moving parts ofthe pump, in particular, are susceptible to failure through repeated use. OBJECTS AND BRIEF SUMMARY OF THE INVENTION

[0010] Accordingly, it is an object ofthe invention to provide a reliable unitary vacuum generator and vacuum extractor cup combination that does not require the physician to make a pumping motion in order to generate a vacuum within the cup. It is a more specific object to provide a vacuum generator assembly that includes an actuator for generating a vacuum from the actuation of a canister or cartridge of compressed gas, such as carbon dioxide (CO₂), and a venturi mechanism. Another object is to provide a vacuum assembly that utilizes pressurized airflow typically available in hospitals to create a localized suction utilizing a venturi mechanism.

[0011] It is a further object ofthe invention to provide a vacuum-generating mechanism that comprises a minimal number of moving parts, thereby minimizing opportunity for failure. A related object is to provide a control mechanism that may be actuated to alternately result in the drawing of a vacuum or the release of a vacuum. A more specific object is to provide an actuation mechanism that provides a rocker switch or a plurality of actuable buttons to alternately draw or release a vacuum.

[0012] It is also an object to provide a hand-held, self-contained vacuum-generating device and to provide a vacuum-generating device in combination with an obstetrical vacuum extractor which are durable and have superior resistance to failure relative to those currently available. A related object in this regard is to provide such devices which include a minimal number of movable parts.

[0013] Another object ofthe invention is to provide a compact, low-cost vacuum generator. It is an additional object ofthe invention to provide a vacuum extractor assembly that may either be made in a low cost and disposable form, or that may be sterilized and recharged for reuse.

[0014] It is another object of the invention to provide a vacuum generator that provides the user with superior control ofthe level of vacuum applied, and that generates a vacuum at a more rapid rate than commercially available devices. It is a related object to provide a vacuum generator that directly generates a vacuum in the vacuum cup upon actuation.

[0015] It is a further object ofthe invention to provide a vacuum cup assembly and a vacuum generator, which may be operated by the physician or user utilizing preferably only one hand.

[0016] An additional object ofthe invention is to provide a vacuum cup assembly that provides direct feedback to the physician regarding the applied vacuum.

[0017] In accomplishing these and other objectives ofthe invention, there is provided an obstetrical vacuum cup assembly, which includes a vacuum cup coupled to a hand-held venturi-propagated vacuum generator, such that the assembly may be maneuvered and a vacuum applied by a single hand ofthe physician. A canister or cartridge of compressed gas, such as carbon dioxide (CO₂), or pressurized air flow typically available in hospitals is fluidly coupled for selective activation to the input of the venturi mechanism, while the output ofthe venturi mechanism is vented to the atmosphere. The hollow interior ofthe cup is fluidly coupled to the suction port ofthe venturi via one or more channels or conduits and a one-way valve such that the flow of gas released from the charged canister or the pressurized air supply through the venturi mechanism results in the establishment of a vacuum within the cup. The vacuum may be released by actuation of a one-way valve to vent the interior ofthe cup to the atmosphere.

[0018] The venturi mechanism is preferably contained in the handle ofthe cup assembly so that the physician may alternately activate or release the vacuum while holding the handle ofthe assembly. In the presently preferred, self-contained cartridge system, the cartridge is likewise contained within the handle. In arrangements wherein pressurized air flow available in hospitals is utilized in lieu of a self-contained cartridge, the source of pressurized air flow is coupled to the venturi mechanism disposed either in the handle, or in a venturi activated "pump" to provide the desired vacuum.

[0019] The actuation ofthe pressurized gas flow through the venturi mechanism to generate the vacuum and the release ofthe vacuum are preferably accomplished by means of a toggle or rocker switch or a plurality of buttons, which are easily accessible to the physician, preferably by the physician's thumb or finger. Thus, the assembly includes a minimal number of movable parts, minimizing the opportunity for failure of the device. The assembly may further include a pressure gauge in fluid communication with the interior ofthe cup such that it displays the vacuum pressure developed within the cup, and a selectively actuated timer positioned such that the physician may also readily reach the timer activation buttons or switches.

[0020] The venturi-generated vacuum arrangement may likewise be utilized for tissue manipulation in other medical procedures. For example, similar suction-type instruments would be particularly useful in minimally invasive procedures, such as laparoscopic procedures or "blind-stick" procedures inasmuch as obstructive tissue may be grasped via suction and held in an unobtrusive position without undesirable damage to the tissue. In such arrangements, the device for actually engaging the tissue itself may be of a form other than an annular cup, as is typically utilized in obstetrical vacuum extraction.

[0021] The venturi-generated vacuum arrangement in conjunction with a cartridge provides a compact, self-contained device that may be utilized in a wide variety of applications, both medical and otherwise, as a venturi activated "pump." In medical devices, such as might be coupled to or included in obstetrical vacuum extractors or the tissue manipulation instruments described above, the entire device may be provided in a sterilized package ready for use by the physician. The device may be constructed for disposal after use, or sterilization, recharging and repackaging. This potential for resposability and reuse is particularly attractive in the medical field due to financial considerations. While such sterilization may not be required in all applications, the venturi arrangement in conjunction with a canister of compressed gas nonetheless provides a convenient, portable vacuum device ready for use without the repetitive squeezing action necessitated by conventional pumps. Non-medical applications may include a hand-held "pump"-type devices utilized in, for example, automotive testing, in lieu of a hand-held manual pumps, such as those disclosed in U.S. Patents 4,775,302, 4,806,084, and 4,954,054, which are likewise assigned to the assignee of this application.

[0022] These and other advantages ofthe invention, as well as additional inventive features, will be apparent from the description ofthe invention provided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIGURE 1 is a front elevational view of an obstetrical vacuum extractor assembly according to teachings ofthe invention and incorporating a bell-shaped cup.

[0024] FIG. 2 is an enlarged front cross-sectional view ofthe vacuum generator subassembly ofthe extractor assembly of FIG. 1.

[0025] FIG. 3 is a top perspective view of a second embodiment of an obstetrical vacuum extractor assembly constructed in accordance with teachings ofthe invention and utilizing a mushroom-shaped cup.

[0026] FIG. 4 is a cross-sectional view ofthe obstetrical vacuum extractor assembly of FIG. 3.

[0027] FIG. 5 is a perspective exploded view ofthe obstetrical vacuum extractor assembly of FIG. 3. [0028] FIG. 6 is a cross-sectional view ofthe obstetrical vacuum extractor assembly of FIG. 3, similar to the view shown in FIG. 4, but illustrating the gas flow for establishing a vacuum within the cup.

[0029] FIG. 7 is a side elevational, partially cross-sectioned view of a third embodiment of an obstetrical vacuum extractor assembly constructed in accordance with teachings ofthe invention.

[0030] FIG. 8 is an enlarged side elevational view ofthe venturi mechanism or vacuum generator of FIG. 7.

[0031] FIG. 9 is an exploded view ofthe venturi mechanism or vacuum generator of FIGS. 7 and 8,

[0032] FIGS. 10 and 11 are cross-sectional views ofthe components ofthe venturi mechanism or vacuum generator of FIGS. 7-9.

[0033] FIG. 12 is a side elevational, partially cross-sectioned view of a fourth embodiment of an obstetrical vacuum extractor assembly constructed in accordance with teachings ofthe invention, and varying from the embodiment shown in FIG. 7 only in placement ofthe vacuum pressure gauge.

[0034] FIG. 13 is a side elevational partially cross-sectioned view of a fifth embodiment of an obstetrical vacuum extractor assembly constructed in accordance with teachings ofthe invention.

[0035] FIG. 14 is a cross-sectional fragmentary view ofthe venturi mechanism or vacuum generator ofthe assembly of FIG. 13. DETAELED DESCRH^»TION OF THE INVENTION

[0036] Turning now to FIG. 1, there is shown an obstetrical vacuum extractor assembly 20 constructed in accordance with teachings ofthe invention. The obstetrical vacuum extractor assembly 20 includes a vacuum generator subassembly 22 and a vacuum cup subassembly 24. The vacuum extractor cup subassembly 24 comprises a hollow vacuum cup 26 having a back wall or base 28 and an annular side wall 30 which opens into a basal opening 32 for placement against the head of an infant (not shown). In the embodiment illustrated in FIG. 1, the vacuum cup 26 is in the general shape of a bell. It will be appreciated, however, that the vacuum cup 26 may be of an alternate design. For example, the hollow vacuum cup 26 may be in the general shape of a mushroom or bowl, as shown in U.S. Patent 5,019,086, which is assigned to the assignee of this application.

[0037] The vacuum extractor cup subassembly further includes a shaft or tube 34 defining a hollow passageway 36 that opens into the inside ofthe cup 26. (See FIG. 2.) It will be noted that in the illustrated embodiments ofthe invention, the shaft is a relatively rigid structure. It will be appreciated, however, that the hollow shaft or tube 34 may be of an alternate design such as a relatively flexible tube constructed of an appropriate material, such as PVC, as shown, for example, in U.S. Patent 6,059,795 to Wallace, or may include a flexible section, as shown, for example, in U.S. Patent 5,019,086. The opposite end ofthe hollow shaft or tube 34 is coupled to the vacuum generator subassembly 22 such that the vacuum generator subassembly 22 may develop a suitable vacuum or lower pressure within the cup 26 when it is placed on the head of an infant during delivery (not shown).

[0038] In order to distribute the vacuum and prohibit the passage of large debris, the cup may be provided with a disk 38 having a plurality of openings 40 therethrough. The disk 38 may be spaced from the back wall 28 ofthe vacuum cup 26 by a plurality of ribs 42, preferably extending radially along the inside surface. In order to prevent further passage of fluid and small debris, the vacuum cup 26 may be provided with an additional filter. In the presently preferred embodiment, a small disk-shaped foam filter 44 is provided in a small annular cavity 46 formed by the ribs 42, side wall 30, and back wall 28 at the base ofthe shaft 34. The foam filter 44 is preferably formed of polypropylene or the like. It will be appreciated, however, that an alternate filter may be provided or may be alternately placed within the obstetrical vacuum extractor cup assembly 20, such as in the stem 34. If desired, the disk 38 may be coupled to the cup by any appropriate means such as gluing or ultrasonic welding or the like to secure the foam filter 44 in position at the base ofthe stem 34, particularly when a disk 38 or the like is not provided.

[0039] To facilitate delivery, the obstetrical vacuum extractor assembly 20 includes a tractioning element 48. In the embodiment illustrated, the tractioning element 48 is in the form of a handle 49 coupled to the stem 34. It will be appreciated, however, that the tractioning element 48 may be of an alternate form such as, for example, one or more arms with handles, such as is disclosed in U.S. Patent 5,803,926, a looped cord, such as is disclosed in U.S. Patent 5,957,931, or any other appropriate design. It will further be appreciated that arrangements in which the tractioning element 48 is not coupled directly to the stem 34 (be it rigid, semi-rigid, or flexible), a stem, nipple, or other opening into the interior ofthe cup is still required for establishment of a vacuum therein.

[0040] In accordance with the invention, the vacuum generator subassembly 22 generates a vacuum within the cup subassembly 24 or other instrument, device or body by a venturi arrangement. It will be appreciated that in alternate embodiments contemplated within the scope ofthe invention, the cup subassembly might alternately be in the form of another vacuum applying medical device such as, for example, a small diameter cup, a rod, or other particularly shaped applicator. Moreover, while the vacuum generator subassembly 24 is shown and described as being contained within the handle ofthe obstetrical vacuum extractor assembly 20, it will be appreciated that the vacuum generator subassembly 24 may be alternately or separately disposed, so long as a fluid connection is established between the vacuum generator subassembly and the applicator body in which the vacuum is to be established, in this case, an obstetrical vacuum extractor cup 26. For example, the vacuum generator subassembly 22 may be provided separate from the tractioning element 48, or the stem 34 may be centered at its attachment to the handle 49.

[0041] As may be seen in FIG. 2, the vacuum generator subassembly 24 comprises a source of compressed gas 50, which is coupled by way of a vacuum generator or venturi mechanism 52 to the stem 34. The source of compressed gas 50 is coupled to the venturi mechanism 52 by one or more conduits or channels 54, and the venturi mechanism 52 to the stem 34 by one or more conduits or channels 56, 58, here disposed in series. For the purposes of this application, the terms conduit and channel shall be utilized to encompass one another, i.e., the use ofthe term channel shall likewise mean conduit, and vice versa. It will be appreciated that the channels through which the gas may flow are illustrated in schematic form in FIG. 2 such that the actual channels would generally be greater in diameter than those illustrated.

[0042] The channels 54, 56, 58 in this embodiment are in the form of semi-rigid polyvinylchlori.de (PVC) tubing or the like. It will be appreciated, however, that these and essentially any or all channels ofthe device may alternately be highly flexible or entirely rigid. A check valve 60 is preferably disposed in the channel 56 to ensure only a one-way flow of air from the stem 34 toward the venturi mechanism 52. While multiple channels 56, 58, a check valve 60 and the stem 34 are provided in the illustrated embodiment to couple the venturi mechanism 52 to the cup 26, for example, those of skill in the art will appreciate that alternate coupling arrangements may be provided to fluidly couple the various flow paths related to the establishment of a vacuum within the cup 26.

[0043] While not shown in detail in this embodiment, the venturi mechanism 52 is generally constructed in accordance with Bernoulli's Principle regarding the structure and operation of a venturi. That is, a flow passage from the channel 54 from the source of compressed gas 50 is reduced to a throat (not visible in FIG. 2) followed by a controlled expansion to a full cross-section which opens to an exhaust port 61. In such an arrangement, the venturi provides a depression in the airflow pressure at a suction port generally disposed at the throat such that the air contained in the channel 56 is drawn into the venturi and out ofthe exhaust port 61 with the expelled gas. Thus, by actuating the source of compressed gas 50 in order to achieve a flow through the venturi mechanism 52, a vacuum is created within the hollow vacuum cup 26, drawing air through the stem 34, the channel 58, the check valve 60, and the channel 56 into the venturi mechanism 52 and out ofthe exhaust port 61.

[0044] In accordance with an important aspect ofthe invention, the source of compressed gas is preferably in the form of a CO₂ cartridge of other compressed gas in a relatively small cartridge 50 such that it can be contained within a small housing or the handle ofthe vacuum extractor assembly 20. The currently preferred size of CO canister 50 is on the order of 12 grams, which has been found to provide adequate stored energy to provide adequate vacuum propagation within an obstetrical vacuum extractor cup during the delivery process. It will be appreciated that use of such a small canister permits the entire vacuum generator subassembly 22 to be readily contained in a small, preferably hand-held package. The cartridge may be proportionally larger or smaller, however, if utilized in a proportionally larger or smaller vacuum generator arrangement. By way of example only, the cartridge may be on the order of 6-20 grams. In this way, the compressed gas is contained within a readily portable cartridge that may be utilized in other handheld vacuum arrangements akin to a pump, including medical and non- medical applications. For the purposes of this disclosure, the term "cartridge" will be used to mean either a cartridge, per se, a canister, or another closed pressurized container housing compressed or pressurized gas.

[0045] The cartridge 50 typically includes a head portion 62 through which the compressed gas may be expelled. In order to control the release ofthe compressed gas, a reed valve or other controllably actuated valving mechanism 64 is provided within a manifold 65 disposed about the head portion 62. Those of skill in the art will appreciate that a reed valve is particularly useful in this arrangement inasmuch as the reed valve includes a spring-like arrangement that allows deflection under pressure to allow gas to pass on one direction only.

[0046] In varied embodiments ofthe invention, the vacuum generator subassembly 22 may be made ready for actuation by advancing the cartridge 50 linearly into engagement with the valve 64 as by loading the cartridge 50 into the handle or by depressing a section ofthe handle, for example, the end 63. Those of skill in the art will appreciate that alternate arrangements for activation are within the purview ofthe invention. By way of example only, a rotatable screw or screw knob in connection with a threaded housing or cartridge, or a camming arrangement may be utilized to advance the cartridge for activation. In this way, the head portion 62 ofthe cartridge 50 may be advanced into contact with a needle or probe 66 associated with the valve 64 such that the needle or probe 66 punctures or penetrates the seal ofthe head portion 62 to open a fluid connection between the cartridge 50 and the valve 64 for the passage ofthe compressed gas. In disposable embodiments, it is particularly appropriate that a section 65 of a closed handle is depressed in order to place the vacuum generating subassembly 22 in condition for operation, while in a sterilizable, reusable embodiment, the handle may include an opening (preferably covered by a door or the like) through which the cartridge 50 may be loaded and unloaded (not illustrated, but may be provided at, for example, end section 63).

[0047] While the venturi-generated vacuum arrangement has been described in detail with regard to a cartridge of compressed gas providing the pressurized gas flow through the venturi mechanism 52, the vacuum generator subassembly 22 may alternately include an input (such as a line) from a source of pressurized gas flow, such as the pressurized airflow wall source readily available in hospitals. In this way, the vacuum generated subassembly may be directly coupled to the pressurized air outlet provided in a hospital room, for example, eliminating the need for rechargeable or disposable cartridges for use in the device. It will be appreciated by those of skill in the art that in such an arrangement, the venturi mechanism and actuation ofthe pressurized gas flow would operate in essentially the same manner as described in reference to a compressed gas cartridge arrangement.

[0048] Returning now to the figures, in order to allow the physician or other user to controllably actuate the valve 64 for generation of a vacuum via the venturi mechanism 52, a switch 70 is provided which is accessible from the outside ofthe handle. In the design illustrated in FIGS. 1 and 2, the switch 70 is disposed along one end 72 ofthe handle 49 such that the physician may grasp the handle 49 with his fingers and palm, and then access the switch 70 with his thumb. The switch 70 is coupled to the valve 64 for actuation thereof either directly or by any appropriate actuator 74. Here, the switch 70 is coupled to the valve 64 by a depressible lever 74 which is spring biased such that the depression ofthe switch 70 operates against the spring bias to actuate the valve 64. It will be appreciated by those of skill in the art that this arrangement for generation of a vacuum does not require the continual pumping with the user's hand, but, rather, merely the press of a button.

[0049] To provide the physician with immediate control ofthe vacuum level within the cup 26, a vacuum relief valve 76 is also provided. While the vacuum relief valve 76 may take on other appropriate forms, in this embodiment, it is preferably in the form of a similarly spring-biased reed valve that allows flow in only one direction, i.e., away from the interior ofthe cup 26. The vacuum relief valve 76 may be controllably actuated by the physician via a switch 78. Preferably, the switch 78 is likewise by the physician's thumb, and may be actuated in a manner similar to the switch 70. In the embodiment illustrated, the vacuum actuation switch 70 and the relief valve switch 78 are advantageously both a part of a single rocker switch. In this way, the physician may use his thumb to alternately actuate or release the vacuum, depending upon which side ofthe rocker switch is depressed in order to obtain a desired vacuum level within the cup 26. It will be appreciated, however, that the actuation and relief valve switches may be of an alternate design, such as, for example, depressible buttons.

[0050] The input side 82 ofthe relief valve 76 is coupled to the hollow interior 36 of the stem 34 by a conduit or channel 84, while the output side 86 ofthe relief valve 76 is open to a port 88 via a conduit or channel 90. As with the channels 64, 66, and 68, the channels 84 and 90 are preferably formed of semi-rigid PVC tubing or the like. It will thus be appreciated that by pressing the switch 78, the physician actuates the relief valve 76 to place the hollow interior ofthe cup 26 in fluid communication with the port 88 via the passageway 36 of the hollow shaft 34, the channel 84, the valve 76, and the channel 90 to provide ambient air to the hollow interior ofthe cup 26 to relieve or reduce the vacuum by allowing an equalization of or reduction ofthe differential between pressures between the atmosphere and the interior ofthe vacuum cup 26.

[0051] In order to provide the physician with concurrent information regarding the pressures developed within the cup 26, a vacuum pressure gauge 96 is provided. The pressure gauge 96 is in fluid communication with the hollow interior ofthe vacuum cup 26 by way of a conduit or channel 98. The vacuum pressure gauge 96 may be mounted to the assembly 20 by any appropriate structure at any appropriate location, and may be mounted to remain stationary or to rotate so that the physician may rotate the pressure gauge 96 to the most desirable position for viewing during delivery.

[0052] While an alternate arrangement may be provided, the illustrated vacuum generator subassembly 22 includes a junction 99 which allows fluid connection from the interior ofthe cup 26 simultaneously to channel 98 in communication with the vacuum pressure gauge 96, the channel 56 in communication with the venturi mechanism 52, and to the channel 84 in communication with the vacuum relief valve 76. In the illustrated embodiment, the junction 99 is in the form of a "T-connector" which is disposed between the channel 58 (that is in direct communication with the interior 36 of the stem 34 and the interior of he cup 26), and the channels 84 (leading to the relief valve 86) and 56 (which ultimately leads to the venturi mechanism 52), although an alternate design may be provided.

[0053] The assembly 20 may additionally include a timer (not shown) that preferably including one or more buttons for activating, pausing, reactivating, and resetting the timer. Thus, the timer preferably allows the physician to time individual cycles of use of he extractor assembly 20 and periods of rest, as well as the total lapsed time for application ofthe vacuum force. The timer may be of any known design, so long as it is positioned such that it is readily actuated by the physician's hand holding the vacuum generator subassembly 22 and easily viewed by the physician, preferably without removing the hand from the handle 49. In this regard, the disclosure of U.S. Application 60/286,856, which is likewise owned by the assignee of this application, is hereby incorporated by reference.

[0054] A second embodiment ofthe invention is illustrated in FIGS. 3-6. (In describing the second embodiment, in general, reference numbers similar to those ofthe first embodiment will typically be utilized in the description ofthe second embodiment, but a "1" will be added before the reference number.) The obstetrical vacuum extractor assembly 120 of FIGS. 3-6 includes a vacuum generator subassembly 122 and a vacuum cup subassembly 124, as in the first illustrated embodiment. In this embodiment, however, the hollow vacuum cup subassembly 124 includes a mushroom-shaped hollow vacuum cup 126. As in the first embodiment, the hollow interior ofthe vacuum cup 126 is fluidly coupled to the vacuum generator subassembly 122 by the hollow passageway 136 within the shaft 134. The vacuum cup subassembly 124 is the same or similar to the vacuum cup subassembly 24 shown in FIGS. 1-2 in essentially all other ways. It will be appreciated by those of skill in the art that the all statements regarding possible variances in the design ofthe assembly 20 shown in FIGS. 1-2 apply equally to the embodiment shown in FIGS. 3-6, and vice versa, as well as applying equally to all other embodiments. For example, in order to provide a comfortable grip, the tractioning element 148 in the embodiment of FIGS. 3-6 includes a plurality of depressions 147 adapted to receive the user's fingers. Such depressions 147 might have readily also been included in the embodiment of FIGS. 1-2.

[0055] Turning now to the vacuum generator subassembly 122, the components of the subassembly are preferably disposed within a housing 149. In order to facilitate fabrication and assembly ofthe subassembly 122, the housing 149 is preferably molded as one or more shell components 149a, 149b into which the components ofthe subassembly 122 can be inserted and around which the shell components 149a, 149b can be closed to contain the inner workings. As shown in FIG. 5, the shell components 149a, 149b can include mating structure, such as various protrusions along the inner surface which facilitate assembly, both ofthe vacuum generator subassembly 122 into the shell, and ofthe shell components 149a, 149b together. For example, as best seen perhaps in FIGS 4-5, cooperative bosses 149c may be provided along the inner surfaces ofthe shell components 149a, 149b to maintain the relative positions ofthe shell components 149a, 149b when assembled. Alternately, or additionally, the respective walls ofthe shell components may include other mating structure.

[0056] In order to allow the replacement or recharging ofthe cartridge 150, a door 165 is provided along the housing 149. The door 165 may be hinged or otherwise connected. In this embodiment, the door 165 is connected to the housing 149 by a rivet assembly or a receptacle and post 165b, 165c. Advantageously, the housing shell components 149a, 149b are secured together by this same receptacle and post 165b, 165c during assembly. Alternately, and preferably, this connection may be made by a male post and a female receptacle that could both be molded directly as a part ofthe handle halves, the two housing shell components 149a, 149b ofthe housing 149 being snap-fit together.

[0057] The cartridge 150 itself is contained within a sleeve 163 within the housing 149. In order to advance the cartridge 150 into the proper position in within the sleeve for selective actuation, a camming arrangement is provided. More specifically, a cam 165a is disposed at the end ofthe cartridge 150 opposite the head 162. In this embodiment of he invention, the cam 165a is disposed at the hinged connection ofthe door 165 to the housing 149. In this way, as the door 165 is pivoted into a closed position, the cartridge 150 rides along the eccentric surface ofthe cam 165a to advance the cartridge 150 within the sleeve 163 to move it into the proper position for further activation. It will be appreciated by those of skill in the art, however, that cam 165a may be alternately designed, arranged or activated to ready the cartridge for further activation.

[0058] In assembly, the head portion 162 ofthe cartridge 150 engages a controllably actuated valving mechanism 164. The valving mechanism 164 is actuated by a depressible button 170 disposed along a surface 172 ofthe housing 149 that is readily accessible by the user. In this embodiment, the surface 172 is the top surface. As illustrated, the depressible button 170 is a cantilevered button that is integrally molded with one ofthe shell components 149a. The button 170 further includes a protrusion 170a that extends into the interior ofthe housing 149 and is disposed to engage and actuate the controllably actuated valving mechanism 164 to controllably release compressed gas from the cartridge 150 to initiate and apply a vacuum.

[0059] The sleeve 163 also includes a manifold or channel 154, as well as the venturi mechanism 152 itself, which operated in a like manner to the assembly 20 illustrated and described with regard to FIGS. 1 and 2. Thus, pressurized gas (see arrow A in FIG. 6) expelled from the cartridge 150, through channel 154 (see arrow B in FIG. 6) and the venturi mechanism 152, and are expelled from an exhaust port 161 to the atmosphere (in this case the interior ofthe housing 149 - see arrow C in FIG. 6). In the embodiment of FIGS. 3-6, the interior ofthe hollow cup 126 is fluidly connected to the throat or suction port ofthe venturi mechanism 152 by the hollow passageway 136 within the shaft 134, and channels 158, 156, and 155 (see arrows D, E, F, and G in FIG. 6). One or more valves may be interposed along this flow path, for example, at 199 and/or 160. Although an alternate arrangement may be provided, in this embodiment, the passageway 136, channels 158, 156, 155, and the valves 199, 160 act as a coupler, coupling the hollow interior ofthe cup 126 to the throat ofthe venturi mechanism 152. In alternate embodiments, this coupler may be comprise fewer or greater numbers of passageways, channels, and valves. The arrangement may include a "quick disconnect coupler" of a given design. A pressure gauge 196 may likewise be fluidly coupled to the interior ofthe cup 126, for example, via a channel 198 or valve connected to one of the channels 156 to display the vacuum pressure developed within the cup 126 (see arrow H in FIG. 6). While the channels 158, 156 and 155 are shown as substantially rigid, molded structures in the embodiment illustrated in FIGS. 3-6, it will be appreciated that these channels could readily be formed of flexible or semi-rigid tubing or the like. If flexible tubing, for example, was utilized in the illustrated arrangement, the vacuum generator subassembly 122 could likely be made considerably smaller than the forms illustrated herein.

[0060] The vacuum relief valve 176 of this embodiment is a manually actuated by a button 178, which advantageously is disposed along the surface 172 ofthe housing 149 substantially adjacent the vacuum actuator button 170. As with the vacuum actuator button 170, the relief valve button 178 is of a cantilevered design and is integrally molded with one ofthe shell components 149b ofthe housing 149.

[0061] The vacuum relief valve 176 itself is in the form of an opening 188 between the channel 156 and the atmosphere (in this case the interior ofthe housing 149) which is covered by a selectively removable cover 202. The selectively removable cover 202 is biased into the closed position, here by an elastomeric band 204. In this embodiment, the band 204 itself also acts as the cover 202 over the opening 188.

[0062] As may best be seen in FIGS. 4 and 5, in order to move the cover 202 from the opening 188, a cantilevered arm 206 is provided which extends through the band 204 such that flexing the arm 206 outward removes the band 204 from the opening 188 to permit pressure equalization. This cantilevered arm 206 is coupled to the vacuum relief button 178 by an arm 208, which extends downward from the vacuum relief button 172. In this way, when the user depresses the vacuum relief button 172, the arm 208 forces the cantilevered arm 206 and, therefore, the band 204 away from the opening to allow for pressure equalization. It will be appreciated, however, that alternate vacuum relief mechanisms may be provided.

[0063] A third embodiment ofthe invention is illustrated in FIGS. 7-11. (In describing the third embodiment, in general, reference numbers similar to those ofthe first and second embodiments will typically be utilized in the description ofthe third embodiment, but a "2" will be added before the reference number.) The obstetrical vacuum extractor assembly 220 of FIG. 7 includes a vacuum generator subassembly 222 and a vacuum cup subassembly 224.

[0064] In this embodiment, the housing 249 may be a unitary, molded element having a number of channels or bores molded therein, or it may be molded as separate halves that are subsequently sealed together to form the channels or bores. It will be appreciated that, as with the first and second embodiments, the housing 249 may alternately be a hollow structure with rigid, semi-rigid or flexible channels assembled into the housing 249.

[0065] The pressurized cartridge 250 is received in a bore 263 in one end ofthe housing 249, protruding from the end thereof for easy loading and replacement. When assembled, the head portion 262 ofthe cartridge 250 is received within a manifold 265, which is sealed within the bore 263 and includes a needle or probe 266.

[0066] In order to fluidly couple the cartridge 250 to the venturi mechanism 252, a controllably actuated valve 264 is disposed between the venturi mechanism 252 and the manifold 265 and/or cartridge 250. Thus, as the cartridge 250 is advanced into the bore 263, the needle or probe 266 punctures or penetrates the seal ofthe head portion 262 to open a fluid connection between the cartridge 250 and an adjacent valve 264. In this embodiment, the controllably actuated valve 264 may be selectively actuated by one of the physician's fingers (not shown) by depressing the lever or button 270. As may be seen in FIG. 7, when the physician depresses the button 270, the button 270 advances a through opening or connection 274 into position between the manifold 265 and venturi mechanism 252 to open a fluid connection therebetween. Preferably, the button 270 is outwardly biased by a spring or other mechanism such that the connection 274 ofthe valve 264 returns to its normally closed position when the physician releases the button 270.

[0067] The venturi mechanism 252 itself is shown in greater detail in FIGS. 8-11. More specifically, in this embodiment, the venturi mechanism 252 includes first and second elements 252a, 252b. As best seen in FIGS. 10 and 11, flow from the valve opening 274 is in fluid communication with the inlet into channel 254. Channel 254 then gradually and smoothly reduces to a throat 253. The throat 253 is then expanded to a full cross-section channel 257, which opens to an exhaust port 262. As high pressure gas is advanced through inlet channel 254, the narrowed throat 253, and the outlet channel 257 to the exhaust port 262, a depression in the flow pressure is created at the throat 253 such that air contained in channel 258 is drawn through opening or suction port 255 (see FIG. 7). In this way, movement ofthe compressed gas through the venturi mechanism creates a vacuum within the hollow vacuum cup 226, drawing air through the stem 234, channel 258, and opening 255 into the venturi mechanism 252 and out of the exhaust port 262.

[0068] The elements 252a, 252b ofthe venturi mechanism 252 itself are structured such that they may be readily molded, sealed to each other, and then disposed within a channel or bore 259 within the housing 249. In order to seal the venturi mechanism 252 within the bore 259, annular seals 261a, 261b are provided between the first and second elements 252a, 252b and the bore 259. In the illustrated, preferred embodiment, both the first and second elements 252a, 252b include annular recesses 263 a, 263b for receiving the annular seals 261a, 261b. As may be seen in FIG. 7, the venturi mechanism 252 is disposed within the bore 259 such that the suction port 255 ofthe venturi mechanism 252 is disposed substantially adjacent the channel 258. It will be appreciated by those of skill in the art that seals 261a, 261b disposed in recesses 263 a, 263b along either side ofthe opening 255 and the channel 258 seal the venturi mechanism 252 within the bore 259. In this way, a sealed connection is established between the channel 258 and the suction port 255 such that any vacuum resulting at the opening 255 is drawn through the channel 258, the stem 234, and the cup 226.

[0069] As with the first two embodiments, the assembly 220 also preferably includes a pressure gauge 296. In this embodiment, the pressure gauge 296 is fluidly coupled to both the venturi mechanism 252 and cup 226 by a channel 298. As with channel 258, the channel 298 opens into a section of bore 259/venturi 252 that is sealed between seals 261a, 261b. In this way, both channels 258 and 298 are directly fluidly coupled to the opening 255 into the venturi mechanism 252 and will experience like vacuum pressures.

[0070] The pressure gauge 296 may be coupled to the assembly 220 by any appropriate means. For example, in the embodiment of FIG. 7, the vacuum gauge 296 is embedded within the molded housing 249, while in the embodiment of FIG. 12, the vacuum gauge 396 is removably sealed within a bore 398 in the housing 349. In all other respects, the assemblies 220, 320 of these embodiments are essentially the same.

[0071] The vacuum within the cup 226, 326 may be released by means of a vacuum relief valve 276, 376, which is interposed in channel 258, 358 and disposed along a lower portion ofthe housing 249, 349 in the embodiments of FIGS 7 and 12. The vacuum relief valve 276, 376 may be of any appropriate design, but, in these embodiments includes a depressible button 278, 378 for actuation ofthe valve 276, 376 similar in design to the actuation valve 264, 364. When the physician depresses the button 278, 378 ofthe vacuum relief valve 276, 376, the valve will fluidly connect the interior of he cup 226, 326 to the atmosphere to allow pressure reduction or equalization. [0072] A fifth embodiment ofthe invention is illustrated in FIGS. 13 and 14. This embodiment differs from the embodiment of FIGS. 3-6 in that the fluid connection between the cartridge 450 and the venturi mechanism 452 is provided by both a manifold 454 and an elongated channel 454a. The elongated channel 454a in this embodiment is formed by a flexible polymeric tube. It has been determined that the inclusion of such an elongated channel reduces any opportunity for the vacuum generator subassembly 422 to "freeze up" during usage.

[0073] An enlarged fragmentary view ofthe venturi mechanism 452 ofthe embodiment of FIG. 13 is shown in FIG. 14. As pressurized gas from the cartridge 450 (preferably CO₂) flows into the venturi or vacuum generator 452 through port 451 and the small orifice 453, the gas must increase its velocity in order to maintain a constant flow rate. As defined by Bernoulli's equation for mass flow, when velocity increases, the dynamic pressure must decrease in order to maintain a constant flow rate. Thus, the pressure ofthe high-speed gas passing through chamber 459 is lower than atmospheric pressure, resulting in a vacuum. Accordingly, the vacuum chamber 459 draws in gas through the suction port 455, which in this case is fluidly attached to a vacuum cup, until such time as equal pressures are established between the vacuum chamber 459 and the suction port 455/the vacuum cup 426. The resulting combined stream of gas from the pressurized source (cartridge) 450 and gas from the vacuum cup 426 is then exhausted through an exit port 457 into the atmosphere.

[0074] In summary, the invention provides a compact, convenient extractor assembly 20 or other device, wherein the physician may control the usage ofthe assembly 20 entirely with one hand, leaving the other hand free for other functions. The device provides the physician with all necessary information for providing a safe application ofthe vacuum extractor during the delivery process.

It will be appreciated by those of skill in the art that, although the disclosed embodiments ofthe vacuum generator subassemblies 22 are illustrated herein as coupled to obstetrical vacuum extractor cups, the vacuum generator subassemblies of this type may alternately be utilized with any number of medical or other devices. Such usages may be particularly appropriate when vacuum generator is a self-contained mechanism, and utilizes small CO₂ canisters, such as the presently preferred 12-gram size, are utilized in the device. In other words, such a vacuum generator subassembly may be utilized, in effect, in a manner similar to a hand-held pump, such as are disclosed, for example, in U.S. Patent 4,806,084, which is likewise assigned to the assignee ofthe present invention. For example, the vacuum generator subassembly may be utilized with a vacuum-type surgical retractor or the like. Alternately, the vacuum generator subassembly may be utilized in non-medical devices, such as testing equipment utilized in devices utilized to test engines. In such alternate arrangements, the obstetrical vacuum extractor cup would simply be replaced by the new device or a hose or other coupling to the new device. In such arrangements, any appropriate sealed or sealable coupling arrangement would be suitable to couple the device to the vacuum generator subassembly. It will be appreciated that the device may alternately be designed to be unitary with the vacuum generator subassembly.

Claims

We claim as our invention:

1. A self-contained mechanism for generating a vacuum, the self-contained mechanism comprising: a canister of compressed gas, the canister having an outlet, a venturi mechanism having an inlet fluidly coupled to the canister outlet, an outlet through which gas is exhausted, and a throat fluidly disposed between the venturi inlet and outlet, a vacuum inlet, the vacuum inlet being fluidly coupled to the venturi mechanism whereby gas expelled from the canister outlet passes through the venturi mechanism drawing a vacuum through the vacuum inlet.

2. The self-contained mechanism of claim 1 wherein the canister of compressed gas is a CO₂ canister.

3. The self-contained mechanism of claim 2 wherein the canister of compressed gas is an 6-20 gram CO₂ canister.

4. The self-contained mechanism of claim 2 wherein the canister of compressed gas is a 12 gram CO₂ canister.

5. The self-contained mechanism of claim 1 further comprising a one-way valve disposed between the vacuum inlet and the throat ofthe venturi mechanism.

6. The self-contained mechanism of claim 1 further comprising at least one of a button or switch coupled to the canister outlet for activation thereof.

7. The self-contained mechanism of claim 1 further comprising a coupler coupled to the vacuum inlet.

8. The self-contained mechanism of claim 5 wherein the coupler comprises tubing.

9. The self-contained mechanism of claim 5 wherein the coupler comprises at least molded channel.

10. The self-contained mechanism of claim 75 wherein the coupler is a quick- disconnect coupler.

11. The self-contained mechanism of claim 1 further comprising a pressure gauge fluidly connected to the vacuum inlet, whereby the pressure gauge reads vacuum established at the inlet.

12. An obstetrical vacuum extractor assembly adapted for connection to a source of pressurized gas and for use in an atmosphere, the assembly comprising: a venturi mechanism having an inlet adapted to be fluidly coupled to the source of pressurized gas, an outlet through which gas is exhausted, and a throat fluidly disposed between the venturi inlet and outlet, a vacuum inlet, the vacuum inlet being fluidly connected to the venturi between the venturi inlet and outlet, an obstetrical vacuum extractor cup having a hollow interior and an opening into the hollow interior, a coupler fluidly connecting the opening and the vacuum inlet whereby pressurized gas provided from the source passing through the venturi mechanism draws a vacuum through the vacuum inlet the opening, and the hollow interior ofthe cup.

13. The obstetrical vacuum extractor assembly of claim 12 wherein the source of pressurized gas is a canister of compressed gas.

14. The obstetrical vacuum extractor assembly of claim 13 wherein the canister of compressed gas is a CO₂ canister.

15. The obstetrical vacuum extractor assembly of claim 14 wherein the canister of compressed gas is a 6-20 gram CO₂ canister.

16. The obstetrical vacuum extractor assembly of claim 12 wherein the source of pressurized gas is a pressurized airflow.

17. The obstetrical vacuum extractor assembly of claim 12 further including an actuator for selectively actuating the flow of pressurized gas.

18. The obstetrical vacuum extractor assembly of claim 17 wherein the actuator comprises an actuable switch for actuating the flow of pressurized gas.

19. The obstetrical vacuum extractor assembly of claim 18 wherein the actuable switch comprises a depressible button.

20. The obstetrical vacuum extractor assembly of claim 12 wherein the coupler comprises at least one one-way valve.

21. The obstetrical vacuum extractor assembly of claim 12 wherein the coupler comprises an elongated channel.

22. The obstetrical vacuum extractor assembly of claim 21 wherein the channel comprises a semi-rigid conduit.

23. The obstetrical vacuum extractor assembly of claim 21 wherein the channel comprises a substantially rigid conduit.

24. The obstetrical vacuum extractor assembly of claim 21 wherein the channel comprises a flexible tube.

25. The obstetrical vacuum extractor assembly of claim 12 further comprising a vacuum release mechanism fluidly coupled to the hollow interior ofthe cup whereby actuation ofthe vacuum release mechanism fluidly couples the hollow interior ofthe cup to the atmosphere.

26. The obstetrical vacuum extractor assembly of claim 25 wherein the vacuum release mechanism comprises a selectively actuable valve.

27. The obstetrical vacuum extractor assembly of claim 26 wherein the vacuum release mechanism further comprises a selectively actuable switch for actuating the actuable valve.

28. The obstetrical vacuum extractor assembly of claim 27 wherein the selectively actuable switch comprises a depressible button.

29. The obstetrical vacuum extractor assembly of claim 26 wherein the selectively actuable valve is a one-way valve.

30. The obstetrical vacuum extractor assembly of claim 26 wherein the selectively actuable valve comprises a valve opening into the coupler and a cover disposed over the valve opening, the cover being biased into position over the valve opening, and the cover being selectively removable from the valve opening to couple the hollow interior ofthe cup to the atmosphere.

31. The obstetrical vacuum extractor assembly of claim 12 further comprising a housing, the venturi mechanism being disposed within the housing.

32. The obstetrical vacuum extractor assembly of claim 18 further comprising a housing, the venturi mechanism being disposed within the housing, and wherein the actuable switch is accessible from outside ofthe housing.

33. The obstetrical vacuum extractor assembly of claim 27 further comprising a housing, the venturi mechanism being disposed within the housing, and wherein the actuable switch is accessible from outside ofthe housing.

34. The obstetrical vacuum extractor assembly of claim 12 further comprising a pressure gauge fluidly coupled to the hollow interior ofthe cup.

35. The obstetrical vacuum extractor assembly of claim 34 wherein the coupler fluidly couples the pressure gauge to the hollow interior ofthe cup.

36. The obstetrical vacuum extractor assembly of claim 12 further comprising a timer.

37. The obstetrical vacuum extractor assembly of claim 12 further comprising a second coupler, said second coupler being fluidly coupled to the venturi inlet, said second coupler further being adapted to engage the source of pressurized gas to fluidly couple the venturi inlet to the source of pressurized gas.

38. The obstetrical vacuum extractor assembly of claim 37 wherein the source of pressurized gas is a canister of compressed gas, said assembly further comprising an engaging mechanism whereby the second coupler and the canister may be selectively engaged.

39. The obstetrical vacuum extractor assembly of claim 38 wherein the engaging mechanism includes a cam.

40. The obstetrical vacuum extractor assembly of claim 38 wherein the engaging mechanism includes a screw.

41. The obstetrical vacuum extractor assembly of claim 38 wherein the engaging mechanism includes a depressible button.

42. The obstetrical vacuum extractor assembly of claim 12 further comprising a timer.

43. A vacuum medical device adapted for connection to a source of pressurized gas and for use in an atmosphere, the assembly comprising: a venturi mechanism having an inlet adapted to be fluidly coupled to the source of pressurized gas, an outlet through which gas is exhausted, and a throat fluidly disposed between the venturi inlet and outlet, a vacuum inlet, the vacuum inlet being fluidly coupled to the venturi mechanism between the venturi inlet and outlet, a medical device having a body and a hollow interior, a coupler fluidly connecting the hollow interior and the vacuum inlet whereby pressurized gas provided from the source of high pressure gas passing through the venturi mechanism draws a vacuum through the vacuum inlet and the hollow interior.

44. The vacuum medical device of claim 43 wherein the source of pressurized gas is a canister of compressed gas.

45. The vacuum medical device of claim 44 wherein the canister of compressed gas is a CO₂ canister.

46. The vacuum medical device of claim 45 wherein the canister of compressed gas is an 6-20 gram CO₂ canister.

47. The vacuum medical device of claim 46 wherein the canister of compressed gas is a 12 gram CO₂ canister.

48. The vacuum medical device of claim 43 wherein the source of pressurized gas is a pressurized airflow.

49. The vacuum medical device of claim 43 further including an actuator for selectively actuating the flow of pressurized gas.

50. The vacuum medical device of claim 49 wherein the actuator comprises an actuable switch for actuating the flow of pressurized gas.

51. The vacuum medical device of claim 50 wherein the actuable switch comprises a depressible button.

52. The vacuum medical device of claim 43 wherein the coupler comprises at least one one-way valve.

53. The vacuum medical device of claim 43 wherein the coupler comprises an elongated channel.

54. The vacuum medical device of claim 53 wherein the channel comprises a semi-rigid conduit.

55. The vacuum medical device of claim 53 wherein the channel comprises a substantially rigid conduit.

56. The vacuum medical device of claim 53 wherein the channel comprises a flexible tube.

57. The vacuum medical device of claim 43 further comprising a vacuum release mechanism fluidly coupled to the hollow interior whereby actuation ofthe vacuum release mechanism fluidly couples the hollow interior to the atmosphere.

58. The vacuum medical device of claim 57 wherein the vacuum release mechanism comprises a selectively actuable valve.

59. The vacuum medical device of claim 58 wherein the vacuum release mechanism further comprises a selectively actuable switch for actuating the actuable valve.

60. The vacuum medical device of claim 59 wherein the selectively actuable switch comprises a depressible button.

61. The vacuum medical device of claim 58 wherein the selectively actuable valve is a one-way valve.

62. The vacuum medical device of claim 58 wherein the selectively actuable valve comprises an opening into the coupler and a cover disposed over the opening, the cover being biased into position over the opening, and the cover being selectively removable from the opening to couple the hollow interior to the atmosphere.

63. The vacuum medical device of claim 43 further comprising a housing, the venturi mechanism being disposed within the housing.

64. The vacuum medical device of claim 50 further comprising a housing, the venturi mechanism being disposed within the housing, and wherein the actuable switch is accessible from outside ofthe housing.

65. The vacuum medical device of claim 59 further comprising a housing, the venturi mechanism being disposed within the housing, and wherein the actuable switch is accessible from outside ofthe housing.

66. The vacuum medical device of claim 43 wherein the body comprises a second coupler.

67. The vacuum medical device of claim 43 wherein the body comprises a tube.

68. The vacuum medical device of claim 43 further comprising a pressure gauge fluidly coupled to the hollow interior.

69. The vacuum medical device of claim 68 wherein the pressure gauge is fluidly coupled to the coupler.

70. The vacuum medical device of claim 43 further comprising a timer.

71. The vacuum medical device of claim 43 further comprising a second coupler, said second coupler being fluidly coupled to the venturi mechanism inlet, said second coupler further being adapted to engage the source of pressurized gas to fluidly couple the venturi mechanism inlet to the source of pressurized gas.

72. The vacuum medical device of claim 71 wherein the source of pressurized gas is a canister of compressed gas, said assembly further comprising an engaging mechanism whereby the second coupler and the canister may be selectively engaged.

73. The vacuum medical device of claim 72 wherein the engaging mechanism includes a cam.

74. The vacuum medical device of claim 72 wherein the engaging mechanism includes a screw.

75. The vacuum medical device of claim 72 wherein the engaging mechanism includes a depressible button.

76. A method of developing a vacuum within a medical device, the method comprising the steps of fluidly coupling the medical device to a vacuum inlet fluidly coupled between the inlet and outlet of a venturi mechanism, and actuating a flow of gas from a source of pressurized gas through the venturi mechanism to draw a vacuum in the medical device through the vacuum inlet.

77. The method of claim 76 wherein the actuating step comprises the steps of actuating the flow of gas from a canister of compressed gas.

78. The method of claim 77 wherein the step of actuating the flow of gas from a canister of compressed gas comprises the step of actuating the flow of gas from a CO₂ canister.

79. The method of claim 78 wherein the CO₂ canister is a 6-20 gram canister.

80. The method of claim 79 wherein the CO₂ canister is a 12 gram canister.

81. The method of claim 76 wherein the actuating step comprises the steps of actuating the flow of gas from a continuous pressurized gas source.

82. The method of claim 76 further comprising the step of fluidly coupling an inlet ofthe venturi mechanism to the source of pressurized gas.

83. The method of claim 82 wherein the step of fluidly coupling an inlet of the venturi mechanism to the source of pressurized gas comprises the step of fluidly coupling the inlet ofthe venturi mechanism to the source of pressurized gas through at least one elongated channel.

84. The method of claim 76 wherein the fluidly coupling step comprises the step of fluidly coupling the medical device to the vacuum inlet through at least one oneway valve.

85. The method of claim 76 wherein the actuating step includes the step of selectively actuating a switch.

86. The method of claim 76 wherein the actuating step includes the step of selectively depressing a button.

87. The method of claim 76 further comprising the step of reducing the vacuum in the medical device.

88. The method of claim 87 wherein the reducing step comprises the step of actuating a vacuum release mechanism.

89. The method of claim 87 wherein the reducing step comprises the step of opening a valve to fluidly couple the medical device to a surrounding atmosphere.

90. The method of claim 89 wherein the reducing step further comprises the step of selectively actuating a switch to open the valve to fluidly couple the medical device to the atmosphere.

91. The method of claim 90 wherein the step selectively actuating a switch to open the valve comprises the step of depressing a button.

92. The method of claim 76 further comprising the step of fluidly coupling a pressure gauge to the medical device to measure the vacuum developed within the medical device.

93. The method of claim 76 wherein the medical device is an obstetrical vacuum extractor.

94. A method of developing a vacuum within a hollow body, the hollow body being disposed in an atmosphere, the method comprising the steps of fluidly coupling the hollow body to a vacuum inlet fluidly coupled between the inlet and outlet of a venturi mechanism, coupling the inlet ofthe venturi mechanism to a canister of compressed gas, and actuating a flow of gas from the canister of compressed gas through the venturi mechanism to draw a vacuum in the hollow body through the vacuum inlet.

95. The method of claim 94 wherein the fluidly coupling step comprises the step of fluidly coupling the hollow body to the vacuum inlet ofthe venturi mechanism through at least one coupler.

96. The method of claim 95 wherein the fluidly coupling step further comprises the step of fluidly coupling the hollow body to the vacuum inlet ofthe venturi mechanism through at least one one-way valve.

97. The method of claim 94 wherein the actuating step includes the step of selectively actuating a switch.

98. The method of claim 94 wherein the actuating step includes the step of selectively depressing a button.

99. The method of claim 94 further comprising the step of reducing the vacuum in the hollow body.

100. The method of claim 99 wherein the reducing step comprises the step of actuating a vacuum release mechanism.

101. The method of claim 99 wherein the reducing step comprises the step of opening a valve to fluidly couple the hollow body to the atmosphere.

102. The method of claim 101 wherein the reducing step further comprises the step of selectively actuating a switch to open the valve to fluidly couple the hollow body to the atmosphere.

103. The method of claim 102 wherein the step selectively actuating a switch to open the valve comprises the step of depressing a button.

104. The method of claim 94 further comprising the step of fluidly coupling a pressure gauge to the hollow body to measure the vacuum developed within the hollow body.

105. The method of claim 94 wherein the step of coupling a venturi mechanism to a canister of compressed gas comprises the step of coupling the venturi mechanism to a CO canister.

106. The method of claim 105 wherein the CO₂ canister is a 6-20 gram canister.

107. The method of claim 106 wherein the CO₂ canister is a 12 gram canister.

108. A self-contained, hand-held mechanism for generating a vacuum, the mechanism comprising: a coupler for connection to a source of pressurized gas, a venturi mechanism having an inlet fluidly coupled to the coupler, an outlet through which gas is exhausted, and a throat fluidly disposed between the venturi inlet and outlet a vacuum inlet, the vacuum inlet being fluidly coupled to the venturi mechanism between the venturi inlet and outlet whereby gas expelled from the source passes through the venturi mechanism drawing a vacuum through the vacuum inlet.