Patent Publication Number: US-11027065-B2

Title: Medical administration barrel with grooves and method of sealing same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of co-pending U.S. patent application Ser. No. 15/758,890, titled “Medical Administration Barrel with Grooves and Method of Sealing Same”, filed on Mar. 9, 2018, which is a section 371 of International Application No. PCT/US15/49588, filed Sep. 11, 2015, which was published in the English language on Mar. 16, 2017 under International Publication No. WO 2017/044112 A1, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention generally relates to a medical administration barrel and a method of sealing the barrel, and, particularly, to a medical administration barrel having grooves assisting in minimizing headspace between a piston and substance within the barrel during the sealing process. 
     Vacuum piston placement is a piston placement process utilized to insert a piston into an open end of a pre-filled container in order to seal off the substance within the container in an airtight manner from the exterior environment. Generally, the piston and the pre-filled container are exposed to a vacuum, i.e., a pressure lower than atmospheric pressure, and then the piston is thereafter sealingly engaged with the open end of the container. The exterior of the piston and container assembly is thereafter restored to atmospheric pressure, such that a pressure differential is created across the piston between the proximal and distal surfaces thereof. The pressure differential drives the piston down the barrel until the friction force balances the pressure difference. Afterwards, the piston may be further advanced, e.g., by a pushing member, until pressure equilibrium is reached across the piston. 
     One drawback of the vacuum piston placement process is that where a low volume of substance is filled in a larger container, a large amount of headspace, i.e., the space between the distal surface of the piston and the substance, may still remain after the piston reaches the position associated with pressure equilibrium. For example, the headspace volume may equal approximately 30% of the volume of the substance filled within the container. 
     One approach to minimizing headspace between the piston and the substance filled inside the container may be to utilize smaller containers. For example, a container may be sized to fit only the piston height, in addition to the length associated with the desired volume of the filled substance. However, where an administration system located behind the piston is utilized to drive the piston forward during use of the container (e.g., when injecting the substance within the container into a recipient), the smaller sized container may not have the necessary space to accommodate the administration system behind the piston. Accordingly, where an administration system is present, the longer container is necessary. 
     Nonetheless, the sealed container may be exposed to different chemical and/or environmental changes during transport that may potentially cause retraction and ejection of the piston out of the open end of the container. For example, the container may be exposed to sub-atmospheric pressure during air transportation, or travel through high elevation regions, which may lead to retraction of the piston. As another example, the container may be exposed to extreme temperatures, which may lead to retraction of the piston. As yet another example, an internal reaction of the substance within the container may cause a change in headspace gas pressure, which may also lead to retraction of the piston. Further, the relatively large air bubble constituting the headspace and trapped within the container may be problematic when dispensing the substance thereafter. 
     Therefore, it is desirable to manufacture a container configured to receive the piston and, if employed, an administration system behind the piston, and also assist in further advancing the piston into the container when utilizing the vacuum piston placement process, to minimize headspace volume. 
     BRIEF SUMMARY OF THE INVENTION 
     Briefly stated, one aspect of the present invention is directed to a method of minimizing headspace between a substance filled in a medical administration barrel and a piston sealing off an open proximal end of the medical administration barrel. The medical administration barrel has at least one groove in an interior wall thereof, the at least one groove defining a length extending a distance from the open end of the medical administration barrel toward an opposing distal end of the medical administration barrel. The at least one groove permits fluid to bypass the piston when positioned along the at least one groove. 
     The method comprises the steps of sealingly engaging a vacuum enclosure with the proximal open end of the medical administration barrel, the vacuum enclosure receiving the piston therein; applying a vacuum to an interior of the sealed vacuum enclosure and medical administration barrel, such that pressure within the sealed vacuum enclosure and medical administration barrel is less than pressure external to the medical administration barrel; physically advancing the piston into the medical administration barrel along the length of the at least one groove, the at least one groove permitting fluid to bypass the piston. Thereafter, the method further comprises the step of ceasing physical advancement of the piston upon reaching an initial portion of the interior wall of the medical administration barrel free of the at least one groove, thereby sealingly engaging the interior wall of the medical administration barrel and providing an air-tight seal inside a portion of the medical administration barrel between the piston and a distal end of the medical administration barrel and maintaining the vacuum between the piston and the substance positioned within the medical administration barrel. Lastly, the method comprises the step of disengaging the vacuum enclosure from the proximal open end of the medical administration barrel, thereby relieving a portion of the medical administration barrel between the piston and the proximal open end of the medical administration barrel from the vacuum and creating a pressure differential across the piston causing the piston to slide further toward the substance in the medical administration barrel and minimizing the headspace between the substance and the piston. 
     Another aspect of the present invention is directed to a sealed medical administration barrel. The sealed medical administration barrel comprises a medical administration barrel having an open proximal end and a closed distal end, and at least one groove in an interior wall thereof. The at least one groove defines a length extending a distance from the open end of the medical administration barrel toward the distal end of the medical administration barrel and defining a substantially constant depth and width along the length thereof. A substance is contained within the medical administration barrel, having a predetermined volume; and a piston is sealing engagement with the interior wall of the medical administration barrel. The at least one groove permits fluid to bypass the piston when positioned along the at least one groove. At least a portion of the piston is positioned distally from the at least one groove, thereby sealing the substance within the medical administration barrel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of a preferred embodiment of the present invention, will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the disclosure, there is shown in the drawings a preferred embodiment of a medical administration barrel. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities shown. In the drawings: 
         FIG. 1  is a cross-sectional, elevational view of an unsealed medical administration barrel, according to a preferred embodiment of the invention; 
         FIG. 2  is a schematic diagram of a vacuum piston placement device utilized for placing a piston in a pre-filled medical administration barrel of  FIG. 1  and sealing an open end thereof; 
         FIG. 3A  is a partial cross-sectional, elevational view of the medical administration barrel of  FIG. 1  mounted in the vacuum piston placement device of  FIG. 2 , with the vacuum enclosure sealingly engaging the open end of the barrel and the piston positioned in the vacuum enclosure; 
         FIG. 3B  is a partial cross-sectional, elevational view of the medical administration barrel of  FIG. 1  mounted in the vacuum piston placement device of  FIG. 2 , with the pushing member physically advancing the piston into the barrel; 
         FIG. 3C  is a partial cross-sectional, elevational view of the medical administration barrel of  FIG. 1  mounted in the vacuum piston placement device of  FIG. 2 , with the piston physically advanced into the barrel by the pushing member and the vacuum enclosure disengaged from the barrel; 
         FIG. 3D  is a partial cross-sectional, elevational view of the medical administration barrel of  FIG. 1  mounted in the vacuum piston placement device of  FIG. 2 , with the piston further advanced into the barrel under the drive of a pressure differential across the piston; and 
         FIG. 3E  is a partial cross-sectional, elevational view of the medical administration barrel of  FIG. 1  mounted in the vacuum piston placement device of  FIG. 2 , with the pushing member further physically advancing the piston into the barrel to substantially achieve pressure equilibrium across the piston. 
     
    
    
     DESCRIPTION OF THE DISCLOSURE 
     Certain terminology is used in the following description for convenience only and is not limiting. The words “lower,” “bottom,” “upper” and “top” designate directions in the drawings to which reference is made. The words “inwardly,” “outwardly,” “upwardly” and “downwardly” refer to directions toward and away from, respectively, the geometric center of the medical administration barrel, and designated parts thereof, in accordance with the present disclosure. Unless specifically set forth herein, the terms “a,” “an” and “the” are not limited to one element, but instead should be read as meaning “at least one.” The terminology includes the words noted above, derivatives thereof and words of similar import. 
     It should also be understood that the terms “about,” “approximately,” “generally,” “substantially” and like terms, used herein when referring to a dimension or characteristic of a component of the invention, indicate that the described dimension/characteristic is not a strict boundary or parameter and does not exclude minor variations therefrom that are functionally the same or similar. At a minimum, such references that include a numerical parameter would include variations that, using mathematical and industrial principles accepted in the art (e.g., rounding, measurement or other systematic errors, manufacturing tolerances, etc.), would not vary the least significant digit. 
     Referring to the drawings in detail, wherein the same reference numerals indicate like elements throughout, there is shown in  FIG. 1  a medical administration barrel, generally designated  10 , in accordance with a preferred embodiment of the present invention. As should be understood by those of ordinary skill in the art, the medical administration barrel  10  may take the form of any container having a cavity or a chamber capable of being filled with a substance, such as, for example, without limitation, a syringe, a cartridge, or the like. 
     The barrel  10  includes an open proximal end  10   a , an opposing a closed distal end  10   b , and a chamber  10   c  therebetween. The chamber  10   c  defines an interior wall  10   d  extending between the proximal and distal ends  10   a ,  10   b . As should be understood by those of ordinary skill in the art, the closed distal end  10   b  may take the form of any sealed end through which fluid communication from outside of the barrel  10  may be established with the chamber  10   c , such as, for example, without limitation, a pierceable septum, a tip having a removable sealing cap, or the like. In the illustrated embodiment, the barrel  10  further includes a flange  12  laterally extending from the open proximal end  10   a . However, the barrel  10  may alternatively not include a flange  12 , or include a differently configured flange  12 . 
     The barrel  10  further includes at least one groove  14  in the interior wall  10   d  thereof, longitudinally extending a length L from the proximal open end  10   a  toward the distal end  10   b . In the illustrated embodiment, the barrel  10  includes a plurality of grooves  14  defining substantially the same length L. Each of the grooves  14  also defines a substantially constant depth and width along the length L thereof. 
     In one embodiment, for example, the medical administration barrel  10  is a 10 ml cartridge. The 10 ml cartridge includes a plurality of grooves  14  defining a length L between approximately 5 mm and approximately 25 mm. Preferably, the grooves  14  define a length L of approximately 20 mm. The plurality of grooves  14  also define a substantially constant depth along the length L, between approximately 0.2 mm and approximately 0.6 mm, and a substantially constant width along the length L, between approximately 1 mm and 4 mm. 
     After a predetermined volume of substance S ( FIGS. 3A-3E ) is filled into the chamber  10   c , e.g., between approximately 3 ml to approximately 10.5 ml, a piston  16  ( FIGS. 2, 3A-3E ) is advanced into the chamber  10   c , via the open proximal end  10   a  of the barrel  10 . The piston  16  is configured to sealingly engage the interior wall  10   d  of the barrel  10 , thereby providing an air-tight seal for the substance S within the chamber  10   c  from the external environment. In one embodiment, the piston  16  includes at least one annular rib  16   a  projecting radially therefrom for slidable sealing engagement with the interior wall  10   d  of the medical administration barrel  10 . In the illustrated embodiment, the piston  16  includes two axially-spaced annular ribs  16   a . However, as should be understood by those of ordinary skill in the art, the piston  16  may include more than two ribs  16   a , or, alternatively, may be constructed with no ribs  16   a , but rather be dimensioned such that the radial periphery thereof entirely or predominantly sealingly engages the interior wall  10   d  and provide and air-tight seal therebetween. 
     The at least one groove  14 , dimensioned as described above, permits fluid, e.g., gas, to bypass the piston  16  when the piston  16  is positioned inside the barrel  10  along the at least one groove  14 . The piston  16 , therefore, seals the chamber  10   c  (and the substance S therein) once at least a portion of the piston  16  is positioned inside the barrel  10  distally from the at least one groove  14 . For example, in the illustrated embodiment, gas may bypass the piston  16  through the grooves  14 , when both annular ribs  16   a  of the piston  16  are positioned along the grooves  14 . Once at least the distal most annular rib  16   a  is advanced past the grooves  14 , the piston  16  seals the chamber  10   c.    
     The piston  16  may be placed into the medical administration barrel  10  via the vacuum piston placement method, understood by those of ordinary skill in the art.  FIG. 2  is a schematic view of a vacuum piston placement device (“PPD”)  50 . As shown, the PPD  50  includes a barrel supporting member  52 , a vacuum enclosure  54 , a pushing member  56 , a vacuum enclosure moving mechanism  58 , an actuator  60 , a pressure control mechanism  62 , and a control unit  64 . 
     As shown, the medical administration barrel  10 , pre-filled with the predetermined volume of substance S, is supported by the barrel supporting member  52  of the PPD  50 . In the illustrated embodiment, the barrel  10  is received within a complementary tube  52   a  of the supporting member  52  and the flange  12  of the barrel  10  is axially supported by a laterally extending flange  52   b  of the supporting member  52 . As should be understood by those of ordinary skill in the art, however, the barrel  10  may be axially supported in the PPD  50  via any of numerous methods, currently know or that later become known. 
     The vacuum enclosure  54  is movable to sealingly engage and cover the proximal open end  10   a  of the barrel  10  in an airtight manner. The vacuum enclosure moving mechanism  58  moves the vacuum enclosure  54  under the control of the control unit  64 . As should be understood by those of ordinary skill in the art, examples of the vacuum enclosure moving mechanism  58  include, but are not limited to, a fluid pressure cylinder device, a motor and the like. 
     The pushing member  56  is disposed to be movable along generally a center axis of the vacuum enclosure  54 . In the illustrated embodiment, the pushing member  56  has a rod-like shape, but may alternatively take the form of other shapes. The pushing member  56  extends through an insertion hole  54   a , formed in a proximal end of the vacuum enclosure  54 , and into an interior chamber  54   b  of the vacuum enclosure  54 . The pushing member  56  is advanceable and retractable through the insertion hole  54   a  in a slidable, airtight manner. For example, the vacuum enclosure  54  may include a sealing member (not shown), in slidable contact with the outer periphery of the pushing member  56 . The actuator  60  advances and retracts the pushing member  56  under the control of the control unit  64 . As should be understood by those of ordinary skill in the art, examples of the actuator  60  include, but are not limited to, a fluid pressure cylinder device, a motor, and the like. 
     The pressure control mechanism  62  includes an air line  66  with one end connected in fluid communication with the vacuum enclosure  54  and the other end connected with a vacuum source  68 , such as, for example, without limitation, a vacuum pump. Under the control of the control unit  64 , the vacuum source  68  of the pressure control mechanism  62  is operated, whereby air in the chamber  54   b  of the vacuum enclosure  54  is withdrawn via the air line  66 , thereby reducing pressure in the vacuum enclosure chamber  54   b  and the medical administration barrel chamber  10   c  to a desired reduced pressure, as explained further below. 
     The process of placing the piston  16  into the pre-filled medical administration barrel  10  via vacuum placement, utilizing the PPD  50 , will next be described. As shown in  FIG. 3A , the medical administration barrel  10 , filled with a predetermined amount of the substance S, is held by the supporting member  52  with the distal end  10   b  of the barrel  10  being oriented at the bottom. The vacuum enclosure moving mechanism  58  then advances the vacuum enclosure  54  into sealing engagement with the flange  12  of the barrel  10 . The piston  16  is initially positioned within the chamber  54   b  of the vacuum enclosure  54 , just above the open proximal end  10   a  of the barrel  10 . Alternatively, the piston  16  may be physically advanced into the barrel  10  and positioned along the extent of the grooves  14 . With this, the chamber  10   c  of the barrel  10  and the chamber  54   b  of the vacuum enclosure  54  are in sealed fluid communication and form an airtight space, isolated from the external atmosphere outside the barrel  10  and the vacuum enclosure  54 . 
     Thereafter, the vacuum source  68  is operated to apply a vacuum to the chambers  54   b  and  10   c , thereby reducing the pressure therein to a predetermined pressure P 2 . Thus, the pressure P 2  inside the chambers  54   b  and  10   c  is lower than atmospheric pressure P 1  (approximately 1 bar) outside of the vacuum enclosure  54  and the barrel  10 . The piston  16 , positioned within the chamber  54   b , or partially within the barrel  10  along the extent of the grooves  14 , is not exposed to a pressure differential, because the chambers  54   b  and  10   c  are in fluid communication. 
     As shown in  FIG. 3B , after the pressure in the chambers  54   b  and  10   c  is reduced to the desired pressure P 2 , the pushing member  56  is advanced by the actuator  60  to engage the piston  16  and physically advance the piston  16  into the barrel  10  through the open proximal end  10   a  thereof toward the substance S. As the piston  16  is physically advanced into the barrel  10 , along the span of the grooves  14 , fluid, e.g., air, within the barrel  10  forward (distal) of the piston  16  is displaceable to the rear of the piston  16  via the grooves  14 , bypassing the piston  16  and the annular ribs  16   a . Therefore, as the piston  16  is advanced into the barrel  10  along the span of the grooves  14 , the pressure P 2  remains the substantially same within both of the chambers  54   b  and  10   c.    
     The pushing member  56  physically advances the piston  16  into the barrel  10  until at least an initial portion of the piston  16  surpasses the grooves  16  and sealingly engages substantially the entire interior wall  10   d  of the groove along a cross-section thereof. In the illustrated embodiment, physical advancement of the piston  16  is ceased when the distal most annular rib  16   a  reaches an initial portion of the interior wall  10   d  of the barrel  10  past the length L of the grooves  14  ( FIGS. 3B, 3C ). Because the distal most annular rib  16   a  is positioned in sealing engagement with the entire interior wall  10   d  of the barrel  10  along a cross-section thereof, i.e., the annular rib  16   a  is located past the grooves  14  previously creating a space between the annular rib  16   a  and the interior wall  10   d , the piston  16  provides an airtight seal inside the portion of the barrel  10  defined between the piston  16  and the distal end  10   b  of the barrel  10 . 
     Thereafter, as shown in  FIG. 3C , the vacuum enclosure  54  is disengaged from the proximal open end  10   a  of the barrel  10 , i.e., the vacuum enclosure  54  is retracted, thereby releasing the vacuum applied to the vacuum enclosure  54  and the barrel  10 . Accordingly, the portion of the medical administration barrel  10  between the piston  16  and the proximal open end  10   a  of the barrel  10  is no longer sealed and returns to atmospheric pressure P 1 . The portion of the barrel  10  between the piston  16  and the distal end  10   b  of the barrel  10  remains sealed, and, therefore, the vacuum pressure P 2  is maintained. Consequently, a pressure differential is created across the piston  16 , driving the piston  16  forward (without being pushed by the pushing member  56 ) further toward the substance S ( FIG. 3D ), as should be understood by those of ordinary skill in the art. 
     As also should be understood by those of ordinary skill in the art, because the piston  16  is sealingly engaged with the interior wall  10   d  of the barrel  10  during the movement thereof due to the pressure differential across the piston  16 , the portion of the barrel  10  between the piston  16  and the distal end  10   b  of the barrel comprises a sealed chamber, and fluid, e.g., air, can no longer escape. Accordingly, as the piston  16  is advanced further toward the substance S, the volume of the headspace between the piston  16  and the substance S decreases, and, therefore, the pressure P 2  progressively increases. The piston  16 , thus, advances further toward the substance S under the drive of the pressure differential across the piston  16  until the increasing pressure P 2 , between the piston  16  and the substance S, is approximately equilibrated with the atmospheric pressure P 1  proximal of the piston  16 . Such forward advancement due to the pressure differential across the piston  16  minimizes the headspace between the piston  16  and the substance S. 
     As the piston  16  is advanced further toward the substance S, and, therefore, pressure differential across the piston  16  approximately equilibrates, frictional forces between the annular ribs  16   a  of the piston  16  and interior wall  10   d  of the barrel  10  may stop the piston  16  before equilibrium between P 2  and P 1  is substantially reached. Accordingly, after the piston  16  ceases forward advancement under the effect of the pressure differential across the piston  16 , the pushing member  56  is re-engaged with the piston  16  and physically further advances the piston  16  toward the substance S to substantially equilibrate the pressure in the barrel  10  between the piston  16  and the substance S, and atmospheric pressure ( FIG. 3E ), thereby further minimizing the headspace between the piston  16  and the substance S. 
     It will be appreciated by those skilled in the art that changes could be made to the embodiment described above without departing from the broad inventive concept thereof. It is understood, therefore, that this disclosure is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present disclosure as defined by the appended claims.