Abstract:
A ventilator system is disclosed herein. The ventilator system includes a collapsible reservoir assembly comprising an outer reservoir and an inner reservoir disposed at least partially within the outer reservoir. The ventilator system also includes a source of gas pneumatically coupled with the outer reservoir, and a controller operatively connected to the source of gas. The controller is configured to regulate the transmission of gas from the source of gas to the outer reservoir in order to compress the inner reservoir and thereby automatically transfer the contents of the inner reservoir.

Description:
FIELD OF THE INVENTION 
       [0001]    This disclosure relates generally to an automatic ventilator system and method. 
       BACKGROUND OF THE INVENTION 
       [0002]    In general, medical ventilator systems are used to provide respiratory support to patients undergoing anesthesia and respiratory treatment whenever the patient&#39;s ability to breath is compromised. The primary function of the medical ventilator system is to maintain suitable pressure and flow of gases inspired and expired by the patient. Medical ventilator systems used in conjunction with anesthesia generally include an automatic system comprising a bellows and a manual system comprising a collapsible reservoir configured to allow a clinician to deliver manual breaths to the patient. 
         [0003]    The manual system is implemented to ventilate a patient by repeatedly compressing and releasing the collapsible reservoir. When the collapsible reservoir is compressed, inhalation gas is transferred to the patient. When the collapsible reservoir is subsequently released, the patient passively exhales due to the lungs&#39; elasticity. Fresh gas is generally continuously introduced into the system, and at least a portion of the patient&#39;s exhaled gas can be recycled and transferred back to the patient. A pressure release valve is traditionally provided to limit the pressure level in the manual system and thereby regulate the volume of inhalation gas transferred to the patient during each compression of the collapsible reservoir. 
         [0004]    One problem with conventional medical ventilator systems relates to the expense associated with two separate sub-systems (i.e., an automatic system comprising a bellows and a manual system). Another problem relates to the packaging constraints imposed by the two separate sub-systems. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    The above-mentioned shortcomings, disadvantages and problems are addressed herein which will be understood by reading and understanding the following specification. 
         [0006]    In an embodiment, a ventilator system includes a collapsible reservoir assembly comprising an outer reservoir and an inner reservoir disposed at least partially within the outer reservoir. The ventilator system also includes a source of gas pneumatically coupled with the outer reservoir, and a controller operatively connected to the source of gas. The controller is configured to regulate the transmission of gas from the source of gas to the outer reservoir in order to compress the inner reservoir and thereby automatically transfer the contents of the inner reservoir. 
         [0007]    In another embodiment, a ventilator system includes a collapsible reservoir assembly comprising an outer reservoir and an inner reservoir disposed at least partially within the outer reservoir. The inner reservoir being pneumatically connectable to a patient, and adapted to retain a patient gas. The ventilator system also includes a source of drive gas pneumatically coupled with the outer reservoir, and a controller operatively connected to the source of drive gas. The controller is configured to regulate the transmission of a drive gas from the source of drive gas to the outer reservoir in order to compress the inner reservoir and thereby automatically transfer the patient gas to the patient. 
         [0008]    In another embodiment, a method includes providing an outer reservoir and an inner reservoir disposed at least partially within the outer reservoir, providing a source of drive gas pneumatically coupled with the outer reservoir. The method also include transmitting a selectable volume of drive gas from the source of drive gas to the outer reservoir in order to compress the inner reservoir and thereby automatically transfer the contents of the inner reservoir. 
         [0009]    Various other features, objects, and advantages of the invention will be made apparent to those skilled in the art from the accompanying drawings and detailed description thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a schematic representation of a ventilator system in accordance with an embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0011]    In the following detailed description, reference is made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration specific embodiments that may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments, and it is to be understood that other embodiments may be utilized and that logical, mechanical, electrical and other changes may be made without departing from the scope of the embodiments. The following detailed description is, therefore, not to be taken as limiting the scope of the invention. 
         [0012]    Referring to  FIG. 1 , a medical ventilator system  10  is schematically depicted in accordance with an embodiment. The medical ventilator system  10  includes a source of ventilator drive gas  12 , a source of fresh gas  14 , a controller  16 , a collapsible reservoir assembly  18 , a diaphragm  20 , and a pneumatic circuit  22 . The pneumatic circuit  22  comprises a plurality of valves  50 - 58  and a plurality of hoses or tubes described in detail hereinafter. 
         [0013]    The source of ventilator drive gas  12  and the source of fresh gas  14  may, for example, comprise a pressurized storage tank or a pump. The source of fresh gas  14  is configured to generally continuously introduce fresh gas into the pneumatic circuit  22  at a selectable rate. The source of ventilator drive gas  12  is regulated by the controller  16  in a known manner. According to one embodiment, the controller  16  may implement feedback from one or more pressure sensors (not shown) to regulate the source of ventilator drive gas  12  in order to maintain a selectable pressure level within the pneumatic circuit  22 . According to another embodiment, the controller  16  may regulate the rate and/or duration during which ventilator drive gas is transmitted in order to deliver a selectable volume of gas to the pneumatic circuit  22 . 
         [0014]    The collapsible reservoir assembly  18  generally includes an inner reservoir  24  adapted to retain patient gas  28 , and an outer reservoir  26 . The inner and outer reservoirs  24 ,  26  comprise pliable bladders or bags that can be compressed and released in order to ventilate a patient. The inner reservoir  24  is disposed within the outer reservoir  26  such that a user can generally simultaneously compress both reservoirs  24 ,  26  with a single squeeze. The collapsible reservoir assembly  18  is commonly referred to as a hand bag, and is so named because an operator can use his or her hand to compress and release the reservoirs  24 ,  26 . According to one embodiment, the outer reservoir  26  comprises a generally translucent material such that an operator can visually confirm inner reservoir  24  compression while squeezing the collapsible reservoir assembly  18 . According to another embodiment, the outer reservoir  26  comprises a reinforced nylon construction rendering it compressible but resistant to stretching. 
         [0015]    The diaphragm  20  comprises a housing  30 , a first diaphragm seal  32 , a second diaphragm seal  34 , and a bleed orifice  36 . The first and second diaphragm seals  32 ,  34  define first, second and third diaphragm chambers  3842 , respectively. The first and third chambers  38 ,  42  are adapted to release gas to atmosphere. According to one embodiment the first chamber  38  is adapted to release gas outside, and the third chamber  42  is adapted to release gas within the room. The introduction of gas into the second diaphragm chamber  40  causes the first and second diaphragm seals  32 ,  34  to expand or translate in an outward direction until the diaphragm seals  32 ,  34  engage an interior surface of the housing  30 . When the diaphragm seals  32 ,  34  engage the interior surface of the housing  30 , the first and third chambers  38 ,  42  become occluded such that gas cannot pass therethrough. 
         [0016]    The manual ventilation operation mode of the medical ventilator system  10  will now be described in detail. When operating in manual ventilation mode, switch valve  50  is in position B identified with a dashed line, which has the effect of occluding position A. 
         [0017]    When an operator generally simultaneously squeezes the inner and outer reservoirs  24 ,  26  of the collapsible reservoir assembly  18 , at least a portion of the patient gas  28  in the inner reservoir  24  is transferred through a carbon dioxide (CO 2 ) absorbent  44 , through the one-way valve  52 , and to the patient  46 . The CO 2  absorbent  44  is configured to scrub or remove any CO 2  from patient gas  28  in a known manner. When the collapsible reservoir assembly  18  is subsequently released the patient  46  passively exhales due to the elasticity of his or her lungs. The exhaled gas from the patient&#39;s lungs is transferred through the one-way valve  54 , and is then combined with fresh gas from the source of fresh gas  14  before being transferred back to the inner reservoir  24 . 
         [0018]    According to one embodiment, an automatic pressure limiting (APL) valve  56  is provided. The APL valve  56  is configured to open when a predetermined pressure level is reached such that excess gas within the pneumatic circuit  22  can be transferred through switch valve  50  and vented to atmosphere via diaphragm chamber  38 . The APL valve  56  can therefore be implemented to automatically limit the pressure level within the pneumatic circuit  22  regardless of variables such as the size of the inner reservoir  24  or the degree to which the inner reservoir  24  is compressed. 
         [0019]    The automatic ventilation operation mode of the medical ventilator system  10  will now be described in detail. When operating in automatic ventilation mode, switch valve  50  is in position A identified with a solid line, which has the effect of occluding position B. 
         [0020]    During automatic ventilation, the controller  16  regulates the source of ventilator drive gas  12  in order to transmit a selectable amount of drive gas into the pneumatic circuit  22 . When drive gas is initially transmitted into the pneumatic circuit  22 , the valve  58  prevents the drive gas from reaching the outer reservoir  26  such that the entire volume of drive gas is directed to the second diaphragm chamber  40 . According to one embodiment, the valve  58  is configured to remain closed until the pressure level within the diaphragm chamber  40  reaches an amount necessary to expand the diaphragm seals  32 ,  34  into engagement with the housing  30  and thereby completely occlude diaphragm chambers  38 ,  42 . 
         [0021]    After the pressure level within the diaphragm chamber  40  reaches an amount necessary to occlude diaphragm chambers  38 ,  42 , the valve  58  opens and drive gas is transferable therethrough to the outer reservoir  26 . The drive gas introduced into the outer reservoir  26  has the effect of compressing the inner reservoir  24 . Providing an outer reservoir  26  that is designed to minimize expansion reduces the volume of drive gas required to compress the inner reservoir  24 , and also maintains consistency pertaining to drive gas volume versus degree of inner reservoir  24  compression. Implementing the controller  16  to transfer drive gas into the outer reservoir  26  causes the inner reservoir  24  to compress in an automatic manner, and thereby also transfers the patient gas  28  to the patient  46  as previously described with respect to the manual ventilation of a patient. 
         [0022]    After automatically compressing the inner reservoir  24  to transfer patient gas  28  to the patient, the controller  16  shuts off the source of ventilator drive gas  12  such that drive gas is no longer introduced into the pneumatic circuit  22 . When the source of ventilator drive gas  12  is shut off, the drive gas within the diaphragm chamber  40  is released through the bleed orifice  36 . As drive gas is released through the bleed orifice  36 , the pressure level with in the diaphragm chamber  40  is reduced thereby allowing the diaphragm seals  32 ,  34  to return to their steady state position and correspondingly opening diaphragm chambers  38 ,  42 . When diaphragm chamber  42  is opened the drive gas within the outer reservoir  26  is released to atmosphere, which has the effect of releasing the inner reservoir  24  from its compressed state. When the inner reservoir  24  is released from its compressed state, the patient  46  can passively exhale due to the elasticity of his or her lungs. The exhaled gas from the patient&#39;s lungs is transferred through the one-way valve  54 , and is then combined with fresh gas from the source of fresh gas  14  before being transferred back to the inner reservoir  24 . 
         [0023]    According to another embodiment, after automatically compressing the inner reservoir  24  to transfer patient gas  28  to the patient, the controller  16  may reduce drive gas flow rate instead of completely shutting off the source of ventilator drive gas  12 . This has the effect of only partially releasing the drive gas within the outer reservoir  26  to atmosphere such that the inner reservoir  24  is correspondingly only partially released from its compressed state. This embodiment can be implemented to maintain positive end-expiratory pressure (PEEP) within the patient&#39;s airway at the end of the expiratory cycle. 
         [0024]    By transmitting a predetermined volume of gas from the source of ventilator drive gas  12  to the outer reservoir  26 , and by generally continuously transmitting the predetermined volume of gas at selectable intervals, the inner reservoir  24  can be periodically compressed and released in a manner adapted to automatically ventilate the patient  46 . Advantageously, the medical ventilator system  10  does not incur the cost or packaging constraints associated with a bellows device that is generally required by conventional automatic ventilation systems. Additionally, the ventilator system  10  enables a user to squeeze the inner and outer reservoirs  24 ,  26  of the collapsible reservoir assembly  18  during automatic ventilation in order to manually supplement the transmission of patient gas  28 . 
         [0025]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.