Abstract:
A blood collection needle assembly includes a holder body having a tube receiving chamber and a needle receiving chamber. A proximal needle is mounted to the holder body and projects into the tube receiving chamber. A distal needle is slidably mounted in alignment with the needle receiving chamber. A spring is provided to urge distal needle into the needle receiving chamber, and a trigger is provided for selectively permitting or preventing proximal movement of the distal needle. A transverse passage between the two needles is formed from a transparent material and provides indication of venus axis. The blood collection needle assembly is used to collect a sample of blood in a conventional manner. After collection of the blood, the trigger is actuated to release the distal needle and the spring propels the distal needle in a proximal direction for safe shielding within the needle receiving chamber of the holder body.

Description:
RELATED APPLICATIONS  
       [0001]    This application claims priority on U.S. Provisional Patent Appl. No. 60/363,362 filed Mar. 11, 2002. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The subject invention relates to a needle assembly for collecting samples of fluid from a patient. The needle assembly includes a needle holder and a needle cannula that can be retracted into the holder after use.  
           [0004]    2. Description of the Related Art  
           [0005]    A needle assembly is used to acquire a sample of blood from a patient and to deposit the blood sample in an evacuated tube. The tube then is shipped from the site of collection to a laboratory for analysis.  
           [0006]    The typical prior art needle assembly includes a needle holder that has opposed proximal and distal ends and a tubular side wall extending between the ends. The proximal end of the needle holder is widely open. However, a wall extends partially across the distal end of the tubular side wall. A needle cannula is mounted to the distal end wall of the prior art needle holder. The needle cannula includes a pointed distal end that extends distally beyond the needle holder and a pointed proximal end that extends centrally within the tubular side wall of the holder.  
           [0007]    The prior art blood collection needle assembly is employed by a phlebotomist who aligns the pointed distal end of the needle cannula with a targeted blood vessel. The phlebotomist then gently eases the pointed distal end of the needle cannula into the blood vessel in a procedure referred to as venipuncture. Most phlebotomists prefer to align the blood collection needle assembly such that the beveled distal end of the needle cannula faces up. Thus, the phlebotomist can visually identify the tip of the needle cannula and can properly align the tip with targeted blood vessel. Additionally, most phlebotomists prefer to have the needle cannula aligned at a very small acute angle to the skin surface of the patient. The small acute angle facilitates visual alignment of the needle cannula with the targeted blood vessel and further helps the phlebotomist to gauge the depth of insertion of the needle cannula.  
           [0008]    The phlebotomist urges an evacuated tube into the open proximal end of the needle holder after the targeted blood vessel has been accessed by the needle cannula. The evacuated tube is moved sufficiently into the needle holder for the pointed proximal end of the needle cannula to pierce the rubber seal that extends across the mouth of the evacuated tube. Thus, blood from the targeted blood vessel will flow through the needle cannula and into the evacuated tube. This flow of blood into the evacuated tube often is the first indication that the targeted blood vessel has been accessed. Unfortunately this initial observable flow of blood may not appear until several seconds after the venipuncture attempt. On some occasions, the phlebotomist may incorrectly interpret this elapsed time as an indication that the targeted blood vessel has been missed. Thus, a phlebotomist may withdraw the needle cannula and conduct the venipuncture procedure again, thereby causing additional discomfort and trauma for the patient.  
           [0009]    Some prior art blood collection needle assemblies are constructed with a transparent flashback chamber for receiving the blood prior to flow of the blood into the evacuated tube. Thus, the flashback chamber can provide an earlier visual indication of successful venipuncture. However, the flashback chamber substantially complicates the prior art blood collection needle assembly and typically will increase both the cost and the size of the prior art blood collection needle assembly.  
           [0010]    The tubular needle holder for the prior art blood collection needle assembly typically is about 2 cm in diameter. Additionally, both the proximal and distal portions of the needle cannula are aligned along the axis of the prior art tubular needle holder. Thus, the needle cannula is spaced radially from the tubular side wall of the needle holder by approximately 1 cm. This relatively large radial dimension prevents the phlebotomist from aligning the needle cannula at a very small acute angle during venipuncture. Thus, the standard blood collection needle assembly must be aligned at an acute angle that is larger than the angle preferred by most phlebotomists.  
           [0011]    An accidental stick with a used needle cannula can be very painful and can transmit disease. Consequently, most prior art blood collection needle assemblies are constructed to reduce the risk of accidental needle sticks. For example, some prior art blood collection needle assemblies have actuators that enable the used needle cannula to be released from the needle holder and into a sharps receptacle without manually unthreading the needle cannula from the needle holder. Other prior art blood collection needle assemblies have a shield that can be moved distally along the needle cannula or that can be rotated into surrounding relationship with the needle cannula. Many prior art shields add to the cross-sectional dimensions of the needle holder, and hence further increase the minimum possible acute angle alignment of the needle cannula for venipuncture. Some prior art shields for blood collection needle assemblies visually obscure the distal end of the needle cannula and/or the evacuated tube. Hence, these prior art shields can impede the view of the collected blood that is required to assure a successful venipuncture. Other prior art shields are sufficiently cumbersome that the phlebotomist may defer employing the shield, thereby creating a significant risk for an accidental needle stick.  
           [0012]    In view of the above, an object of the invention is to provide a blood collection needle assembly that has the distally directed needle cannula positioned and aligned to facilitate venipuncture.  
           [0013]    Another object of the invention is to provide a blood collection needle assembly with a blood flashback indication to provide accurate and early evidence of an acceptable venipuncture.  
           [0014]    A further object of the invention is to provide a blood collection needle assembly that enables an efficient and safe shielding of the needle cannula.  
         SUMMARY OF THE INVENTION  
         [0015]    The subject invention is directed to a blood collection needle assembly. The assembly includes a needle holder that has an elongate body with opposed proximal and distal ends and a blood collection tube chamber extending between the ends. The blood collection tube chamber is open at the proximal end of the body and extends substantially to the distal end of the body. A distal wall partly closes the blood collection tube chamber at the distal end of the body, but includes an aperture that extends axially into the blood collection tube chamber. The body further includes a used needle chamber substantially adjacent the blood collection tube chamber. The used needle chamber has an open distal end and a closed proximal end. However, a vent may communicate with the proximal end of the used needle chamber.  
           [0016]    The blood collection needle assembly of the subject invention further includes a proximal needle cannula mounted to the distal wall of the body and extending into the blood collection tube chamber. The proximal needle cannula includes a sharply pointed proximal end disposed within the blood collection tube chamber and lumen that communicates with both the aperture in the distal wall and with the blood collection tube chamber. A needle-pierceable elastomeric multiple sample sheath may be mounted over the proximal needle cannula, substantially as in prior art needle holders. Thus, an evacuated tube can be urged distally into the open proximal end of the blood collection tube chamber. Sufficient movement of the evacuated tube will cause the rubber stopper that extends across the open end of the evacuated tube to engage the needle-pierceable multiple sample sheath that surrounds the proximal needle of the assembly. Further movement of the evacuated tube will cause the pointed end of the proximal needle to pierce through the elastomeric sheath and through the rubber stopper of the evacuated tube. Thus, the lumen of the proximal needle cannula can be placed in communication with the evacuated blood collection tube substantially as in the prior art.  
           [0017]    The blood collection tube assembly of the subject invention further includes a distal cap securely mounted across the distal wall of the body. The cap and the distal wall of the body cooperate to define a transverse channel that extends from the aperture in the distal wall to the open distal end of the used needle chamber.  
           [0018]    The blood collection tube assembly further includes a distal needle cannula having a prixmal end, a pointed distal end and a lumen extending therebetween. The distal needle cannula is mounted for controlled movement into the used needle chamber. Additionally, the proximal end of the distal needle cannula is configured to communicate with the transverse passage defined between the distal wall of the body and the cap of the needle holder. Thus, communication between the lumen of the distal needle cannula and the lumen of the proximal needle cannula can be achieved through the transverse passage.  
           [0019]    The cap preferably is transparent. Thus, blood flowing through the transverse passage will be readily visible at the distal end of the needle holder. Accordingly, the blood collection needle assembly provides a clear indication that the blood vessel has been accessed properly. This venous indication will occur well before the blood flows into the evacuated tube.  
           [0020]    A biasing means may be provided for biasing the distal needle cannula in a proximal direction and into the used needle chamber formed in the body. The biasing means may be a coil spring concentrically surrounding the distal needle cannula and disposed within a portion of the cap.  
           [0021]    The blood collection needle assembly may further include a trigger that is selectively actuatable from a location externally of the needle holder. The trigger may be operative to hold the distal needle cannula in a distal position for collecting a sample of blood from a patient. The trigger then may be moved to a second position for releasing the distal needle and enabling the biasing means to propel the distal needle cannula in a proximal direction and into a position where the distal needle cannula is safely enclosed within the used needle chamber.  
           [0022]    Communication between the distal needle cannula and the transverse passage may be provided by a transverse aperture near the proximal end of the distal needle cannula. A pair of seals may be mounted in spaced relationship around the distal needle cannula to prevent errant flow of blood from the distal needle cannula. One seal may be disposed to lie proximally of the transverse passage when the distal needle cannula is in the distal position. The second seal may be disposed distally of the transverse passage when the distal needle cannula is in its distal position. Thus, blood flowing through the lumen of the distal needle cannula will be channelized by the seals into the transverse passage and toward the proximal needle cannula.  
           [0023]    The blood collection needle assembly of the subject invention provides the distal needle cannula at an offset or transverse position on the body of the needle holder. Thus, a phlebotomist can align the distal needle cannula at a very small acute angle to the skin of the patient during venipuncture.  
           [0024]    Additionally, the blood collection needle assembly of the subject invention enables automatic shielding to occur without complex telescoping or pivoting shields and immediately upon withdrawal of the distal needle form the patient. Hence, a very high degree of safety can be achieved without complex mechanisms that could impede normal usage of the assembly.  
           [0025]    The seals around the distal needle cannula can affect the speed of withdrawal of the distal needle cannula into the used needle chamber. More particular, the seals may cause air in the used needle chamber to compress and resist the proximal movement of the distal needle cannula. To facilitate proximal movement of the distal needle cannula into the used needle chamber, a vent may be provided at a proximal position in the used needle chamber. The vent can be formed from a material with a selected air flow rate to achieve a desired rate of acceleration of the distal needle cannula into the used needle chamber. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0026]    [0026]FIG. 1 is a longitudinal cross-sectional view of a blood collection needle assembly prior to use.  
         [0027]    [0027]FIG. 2 is a longitudinal cross-sectional view of the blood collection needle assembly after removal of the safety shield and prior to insertion of the evacuated tube into the tube receiving chamber.  
         [0028]    [0028]FIG. 3 is a longitudinal cross-sectional view during venipuncture.  
         [0029]    [0029]FIG. 4 is a longitudinal exploded cross-sectional view showing the blood collection needle assembly after completion of venipuncture and shielding of the distal needle cannula.  
         [0030]    [0030]FIG. 5 is a plan view showing the surface of the cap that faces the body of the needle holder.  
         [0031]    [0031]FIG. 6 is a cross-sectional view taken along line  6 - 6  in FIG. 5.  
         [0032]    [0032]FIG. 7 is a cross-sectional view taken along line  7 - 7  in FIG. 1 and showing the trigger in a first operational position.  
         [0033]    [0033]FIG. 8 is a cross-sectional view similar to FIG. 7, but showing the trigger in an operational position for permitting withdrawal of the distal needle cannula into the needle chamber of the body.  
         [0034]    [0034]FIG. 9 is a schematic cross-sectional view showing the seals disposed adjacent the proximal end of the distal needle cannula. 
     
    
     DETAILED DESCRIPTION  
       [0035]    A blood collection needle assembly in accordance with the invention is identified generally by the numeral  10  in FIGS.  1 - 4 . Blood collection needle assembly  10  includes a holder assembly  12  for holding needles and an evacuated blood collection tube. Holder assembly  12  includes a body  14  with a proximal end  16 , an opposed distal end  18  and a tubular outer wall  20  extending between proximal end  16  and distal end  18 . Holder body  14  further includes a transverse inner wall  22  extending substantially from proximal end  16  to distal end  18  and connecting spaced apart regions on tubular outer wall  20 . Outer wall  20  and inner wall  22  cooperate to define a cylindrical tube receiving chamber  24  and a cylindrical needle receiving chamber  26  in bolder body  14 .  
         [0036]    Holder body  14  is characterized further by a distal wall  28  extending across distal end  18  of holder body  14 . Distal wall  28  is characterized by aperture  30  substantially centrally aligned with tube receiving chamber  24  and an opening  32  substantially centrally aligned with needle receiving chamber  26 .  
         [0037]    Proximal end  16  of holder body  14  defines a wide opening  34  into tube receiving chamber  24 . Opening  34  is dimensioned to slidably receive an evacuated blood collection tube as explained further herein. Proximal end  16  of holder body  14  further includes a proximal wall  36  closing the proximal end of needle receiving chamber  26 .  
         [0038]    Outer wall  20  of holder body  14  includes a transverse slot  38  extending therethrough and communicating with portions of tube receiving chamber  24  adjacent distal end wall  28 . Additionally, inner wall  22  includes a transverse slot  40  substantially adjacent distal end wall  28 . Slots  38  and  40  are aligned and are dimensioned to receive a trigger as explained further herein.  
         [0039]    Proximal wall  36  further includes a vent  42  extending therethrough and communicating with needle receiving chamber  26 . Vent  42  enables a controlled escape of air from needle receiving chamber  26  for controlling the speed of movement of the distal needle into needle receiving chamber  26 , as explained further herein.  
         [0040]    Blood collection needle assembly  10  further includes a proximal needle cannula  44  with a pointed proximal end  46 , a distal end  48  and a lumen  50  extending therebetween. Distal end  48  of proximal needle  44  is mounted to distal wall  28  of holder body  14  such that lumen  50  communicates with aperture  30  and such that proximal needle cannula  44  extends centrally in tube receiving chamber  50 . An elastomeric needle pierceable multiple sample sleeve  52  is securely mounted over proximal needle cannula  44 . Sleeve  52  seals the lumen through proximal needle cannula  44 . However, forces exerted by the stopper of an evacuated blood collection tube will deflect sleeve  52  sufficiently for pointed proximal end  46  of proximal needle cannula  44  to pierce through sleeve  52  and through the rubber stopper of the evacuated blood collection tube.  
         [0041]    The blood collection needle assembly  10  further includes a transparent cap  56  mounted to distal wall  28  of holder body  14 . As shown in FIG. 6, cap  56  includes a generally tubular nose  58  having a needle mounting chamber  60  therein. Needle mounting chamber  60  includes an open proximal end  62  disposed to align with opening  32  in distal end wall  28  of holder body  14  and also to align with needle receiving chamber  26  in holder body  14 . Needle mounting chamber  60  further includes a distal opening  64  dimensioned to slidably receive a needle cannula as explained further below. Distal opening  64  is cross-sectionally smaller than intermediate portions of needle mounting chamber  60 , and hence an annular stop rim  66  is defined adjacent distal opening  64 .  
         [0042]    Cap  56  further includes a transverse passage  68  extending from needle mounting chamber  60  to aperture  30  in distal wall  28  of holder body  14 . Transverse passage  68  thus provides communication between needle mounting chamber  60  and aperture  30  in distal wall  28  of holder body  14 . As noted above, aperture  30  in distal end wall  28  of holder body  14  provides communication with lumen  50  of proximal needle cannula  44 . Hence, passage  68  provides communication between needle mounting chamber  60  and lumen  50  of proximal needle cannula  44 .  
         [0043]    Blood collection needle assembly  10  further includes a distal needle cannula  70  with a proximal end  72 , a pointed distal end  74  and a lumen  76  extending therebetween. Proximal end  52  of distal needle cannula  70  is mounted to a hub  78  that is disposed for sliding sealed engagement in needle mounting channel  60  of cap  56  and in opening  32  in distal end wall  28  of holder body  14 . More particularly, hub  78  includes a proximal seal  80  disposed proximally of transverse passage  68  and a distal seal  82  disposed distally of transverse passage  68 . Additionally, hub  78  includes a transverse aperture  84  between seals  80  and  82 . Transverse aperture  84  provides fluid communication between lumen  76  of distal needle cannula  70  and transverse passage  68  in cap  56 .  
         [0044]    A coil spring  86  concentrically surrounds distal needle cannula  70  and has a proximal end engaged with hub  78  and a distal end engaged with stop rim  66  in nose  58  of cap  56 .  
         [0045]    Distal needle cannula  70  can be telescoped between distal and proximal positions relative to both needle mounting chamber  60  and needle receiving chamber  26 . More particularly, in the distal position, shown in FIG. 1, hub  78  is disposed substantially within needle mounting chamber  60  and adjacent opening  32 , and distal end  74  of distal needle cannula  70  projects distally beyond nose  58  of cap  56 . In this distal position, coil spring  86  is maintained in a compressed condition. However, coil spring  86  can propel distal needle cannula  70  in a proximal direction such that needle hub  78  and distal end  74  of needle cannula  70  are disposed safely within needle receiving chamber  26  and needle mounting chamber  60 .  
         [0046]    Blood collection needle assembly  10  further includes a trigger  90  mounted in slots  38  and  40  of holder body  14 . Trigger  90  includes an actuator surface  92  disposed externally of holder body  14 . Additionally, trigger  90  includes a stepped locking aperture  94  and an elongate aperture  96  between stepped locking aperture  94  and actuator  92 . Stepped locking aperture  94  includes a small diameter portion  98  at a location on trigger  90  furthest from actuator  92  and a large diameter portion  100  closer to actuator  92 . Trigger  90  can be moved transversely of holder body  14  from a first position shown in FIG. I to a second position shown in FIG. 4. In the first position, an end of elongate aperture  96  furthest from actuator  92  is aligned with proximal needle cannula  44 , and small diameter portion  100  of locking aperture  94  aligns with proximal end  80  of hub  78  on distal needle assembly  70 . Small diameter portion  98  of locking aperture  94  is dimensioned to prevent passage of needle assembly  70  into needle receiving chamber  26 . However, digital pressure on actuator  92  moves trigger  90  transversely into the position of FIGS. 4 and 8. In this position, the end of elongate central aperture  96  closest to actutator  92  will align with proximal needle cannula  44 . Additionally, in this position large diameter portion  100  of locking aperture  94  will align with hub  78  of distal needle cannula  70 . Large diameter portion  100  of locking aperture  94  is dimensioned to permit passage of hub  78  of distal needle cannula  70  into needle receiving chamber  26 . Consequently, needle assembly  70  will be propelled under the action of coil spring  86  into needle receiving chamber  26 . As a result, pointed distal end  74  of distal needle assembly  70  will be safely retained within needle receiving chamber  26  or needle mounting chamber  60 .  
         [0047]    The blood collection needle assembly is shipped substantially in the condition shown in FIG. 1, including a rigid safety shield  102  mounted over distal needle cannula  70  and removably engaged with nose  58  of cap  56 . Blood collection needle assembly  10  is used by initially removing safety shield  102  to expose distal needle cannula  70 . The phlebotomist then conducts a venipuncture procedure by aligning pointed distal end  74  of distal needle cannula  70  with a targeted blood vessel, and piercing the skin S and adjacent bodily tissue to access the targeted blood vessel, as shown in FIG. 2. The alignment of distal needle cannula  70  with the targeted blood vessel is facilitated due to the offset position of distal needle cannula  70  relative to holder body  14 . In particular, the offset position of distal needle cannula  70  permits the phlebotomist to hold distal needle cannula  70  at a very small acute angle a relative to the skin of the patient.  
         [0048]    Upon successful venipuncture, blood will flow through the lumen of distal needle cannula  70 , through transverse aperture  84  in needle hub  78  and into transverse passage  68  of transparent cap  56 . The transparency of cap  56  enables visual confirmation of the presence of blood in transverse passage  68 , and hence provides a positive confirmation of successful venipuncture. Furthermore, the close proximity of transverse passage  68  to lumen  76  in distal needle cannula  70  ensures that the venipuncture indication is provided very quickly after the successful venipuncture has been achieved.  
         [0049]    A phlebotomist may sequentially insert and remove several evacuated tubes  104  into tube receiving chamber  24  of holder body  14 . More particular, evacuated tubes  104  are advanced sufficiently into tube receiving chamber  24  for seal  106  on evacuated tube  104  to engage multiple sample sleeve  52  on proximal needle cannula  14 . Continued distal movement of evacuated tube  104  into tube receiving chamber  24  collapses sleeve  52  and causes proximal point  46  on proximal needle cannula  44  to pierce through both sleeve  52  and stopper  106 . Thus, direct fluid communication to the interior of evacuated tube  104  is achieved and an efficient blood flow into evacuated tube will result. Evacuated tube  104  may be removed upon collection of an acceptable volume of blood, and one or more additional evacuated tubes may be inserted into tube receiving chamber  24  for collecting additional samples of blood.  
         [0050]    After collection of the last sample of blood, evacuated tube  104  is withdrawn from tube receiving chamber  24 . The phlebotomist then simultaneously exerts digital pressure on actuator  92  of trigger  90  while exerting a proximal pulling force on blood collection needle assembly  10 . These actions will cause distal needle cannula  70  to be withdrawn from the patient and simultaneously will cause spring  86  to propel distal needle assembly  70  into needle receiving chamber  26  of holder body  14 . The evacuated tubes with samples of blood therein then can be shipped to a laboratory for analysis, and the safely shielded blood collection needle assembly  10  may be deposited in a sharps receptacle.  
         [0051]    While the invention has been described with respect to a preferred embodiment, it is apparent that various changes can be made without departing from the scope of the invention as defined by the appended claims. For example, the invention has been described specifically for collecting samples of blood. However, the assembly can be adapted for collecting other fluid samples.