Abstract:
An adjustable volume control manual resuscitation bag assembly includes a resuscitation bag, a volume control knob, a traction assembly operating in response to adjustment of the control knob, and a follower assembly including a bag compression limiting member and a follower which are moved in response to operation of the traction assembly to adjust and limit the volume of gas delivered by compression of the bag.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Volume control of manual resuscitation bags is an important feature not presently found on commercially available manual resuscitation equipment. Volume control and adjustment is especially important, and may be critical, for resuscitating infants, particularly neonatal care patients. Typical infant and neonatal resuscitation bags have a volume capacity of about 100 ml. Yet for very small patients with such limited lung capacity, it is desirable to limit the volume delivered to the infant or prenatal patient to less than 100 ml, e.g., between about 10 ml and about 60 ml or between about 20 ml and about 80 ml per bag compression. It is to such a volume controllable manual resuscitation bag assembly that the present invention is directed. 
       SUMMARY OF THE INVENTION 
       [0002]    The following description is directed to a manual resuscitation bag apparatus having components capable of providing operator selection and adjustment of the volume of gas delivered to a patient with each resuscitation bag compression. In a preferred embodiment, the resuscitation bag is a bellows or accordion-type bag having a total bag capacity of about 120 ml. The bag is compressed by the operator depressing the distal end of the bag toward the proximal end of the bag. 
         [0003]    The volume selection and adjustment components include a rotatable volume control member secured on the outside of the bag, preferably at the distal end, and volume adjustment components located within the bag. In a preferred embodiment, the volume adjustment components include a follower assembly comprising a bag compression stop member and a follower device movable axially in the bag from the distal end toward the proximal end, and traction assembly components cooperating with the volume control member for moving the follower assembly in response to rotation of the volume control member. 
         [0004]    In a first preferred embodiment, a follower assembly is rotated by a rotatable guide member secured to the volume control member. The follower assembly is moved axially in response to a traction device cooperating with a helical track formed on the follower assembly to urge a rotating follower device axially. The guide member also cooperates with the traction device to support the follower assembly. 
         [0005]    In a second preferred embodiment, the follower assembly does not rotate but is urged axially by a rotatable traction device secured to the volume control member, the traction device cooperating with a helical track formed on the follower assembly. A stationary guide member cooperates with the follower assembly to assist in directing its axial movement. The guide member also cooperates with the traction device to support the follower assembly position in the bag. 
         [0006]    More specific features of the various components, configurations, assembly and operation of the apparatus will be described in the following detailed description. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIGS. 1 and 2  are perspective views from the proximal and distal ends of the manual resuscitation bag assembly, respectively; 
           [0008]      FIG. 3  is an exploded view showing components of the volume control assembly of the apparatus; 
           [0009]      FIGS. 4 and 5  are proximal and distal sectional views, respectively, showing the internal components of the volume control and volume adjustment assemblies; and 
           [0010]      FIG. 6  is a perspective view of volume adjustment assembly components showing other features thereof. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0011]      FIGS. 1 and 2  are external views showing various components of a preferred manual resuscitation bag assembly. Major components illustrated include a resuscitation bag  10 , pressure relief valve assembly  22 , non-rebreathing valve assembly  24  and an extension tube  26 . At the patient end of the apparatus, i.e., the proximal end, is located the non-rebreathing valve assembly  24  and a patient adapter  28 . Typically, when resuscitating a patient, a face mask is used which is attached to the patient adapter  28 . Details of components, designs and operation of a pressure relief valve and a non-rebreathing valve assembly are not described in further detail herein. The extension tube  26  is preferably flexible, and, for example, a corrugated gas delivery tube may be used. 
         [0012]    The resuscitation bag  10 , as shown, is preferably an accordion or bellows-type which is self-inflating and self-rebounding. The bag is manually compressed by an operator depressing the bag at the distal end toward the proximal end or front of the bag, thereby displacing a volume of gas directed and delivered to the patient. The bag is preferably formed of silicon or polyurethane, although other materials such as polyethylene, polypropylene or polyvinylchloride may be used. The latter may be least preferred because of the possibility of undesirable volatile gaseous residues. 
         [0013]    Observing also  FIGS. 3-6 , the volume control member  12  is rotatably secured at the proximal end of the resuscitation bag where it can be readily observed and selectively rotated by the user. The front or exposed face of the volume control member may be provided with indicia marking the different volumes to be selected and provided with lock recesses or detents  18  which cooperate with retractable volume control lock  34  to position the selected volume control member and prevent inadvertent rotation. 
         [0014]    The volume adjustment components includes a follower assembly and a traction assembly. The traction assembly includes a guide member secured to and extending from rotatable volume control member  12  and comprises a pair of shafts  11 ,  15 , spaced apart to define an elongated slot  16 . A follower assembly comprises a compression stop plate  13  to which is secured a follower device comprising a cylindrical sleeve  14  on which is formed an elongated flange  17 . Observing also  FIGS. 3 and 6 , flange  17  slidably engages elongated slot  16  and is movable along the slot when the volume adjustment assembly is rotated, as later explained. The pair of shafts and the slot form a guide for axial movement of the follower device  14  forward and backward (proximal and distal) within the resuscitation bag. 
         [0015]    The traction assembly also includes a traction device configured to contact and force movement of the follower device  14  and compression stop plate  13  in response to rotation of the volume control member  12 . In the embodiment illustrated, this operation is controlled by a helical track  27  in the form of a helical groove or recess formed on the interior surface of cylindrical sleeve  14  cooperating with lugs  23  and  25  at the ends of traction device arms  21 ,  29 . The traction device arms extend from and are secured to gas inlet/outlet pipe  20 . The traction device arms  21 ,  29  are stationary and are not driven by rotation of the volume control member. 
         [0016]    In operation, as the volume control member  12  is rotated, the guide member shafts  11  and  15  cause rotation of follower device  14 , and as the sleeve rotates, it is drawn axially, proximally or distally, as the helical track moves along the stationary traction assembly components. Thus, rotation of the volume control member  12  results in rotational and axial movement of stop plate  13  and follower device  14 . The volume of gas displaced by compression of the distal end of the resuscitation bag is determined by the distance between the compression stop member plate  13  and the distal end of the bag. The volume selected by the user results in axial movement of the stop member plate  13  to a position which corresponds to the volume of gas which will be displaced between the compression stop plate and the distal end of the bag when the bag is compressed. 
         [0017]    As an alternative design to that shown in the drawings and previously described, the stationary traction device may contact and operate on the outside of the follower device with the helical track formed on its exterior surface and with the guide member shafts extending into the follower device to force its rotation. 
         [0018]    In another alternative configuration, not shown, the traction assembly comprises a traction device secured to the rotatable volume control member so that rotation of the volume control member will rotate the traction device. The traction device is provided with lugs, teeth or other protuberances received in or otherwise engaging the helical track formed on the outer surface of the follower device. The traction device may be in the form of a rotatable sleeve, or shafts or arms or equivalent components secured to and extending from the volume control plate and which rotate with the volume control plate to urge the follower assembly axially, forwardly or rearwardly, within the bag. The traction assembly also includes a stationary axial guide member rigidly secured to the gas inlet/outlet pipe. The guide member may comprise a flange or equivalent component received in an elongated slot on the interior surface of the follower device. Alternatively, the interior surface of the follower device may be provided with a flange or protuberance received in a slot formed on the guide member. In either case, in this latter described embodiment, the traction device rotates while the follower assembly does not rotate but moves forward or backward (proximally or distally) within the bag. 
         [0019]    As previously noted, the volume control lock  34  is retractable, and preferably biased to the locking position using a compression spring  33  which urges the volume control lock in a locked position against the face of the volume control member to prevent inadvertent rotation once the operator has rotated the member to the selected volume. 
         [0020]    In a preferred embodiment illustrated in  FIG. 1 , an operator may select and adjust the volume delivered with each bag compression in 10 ml increments between 20 ml and 120 ml, as shown on the face of volume control member  12 . However, these volumes are by way of example only. Incremental volume adjustments as well as total bag delivery volume may be modified by various means, for example, by changing the size of the resuscitation bag, modifying the pitch of the helical track groove, changing the design or structure of the volume adjustment components, such as the distance the follower assembly moves in response to rotation of the volume control member, adjusting the length of the shafts, and/or moving the position of the compression stop plate. These as well as other variations and modifications of the different components as well as the arrangement and interaction of components of the apparatus within the purviews of the disclosure and claims herein will be understood by those skilled in the art.