Abstract:
A new tip for a conventional lancer that provides for improved blood flow from a lancet puncture site not located on a patient&#39;s finger. The new lancer tip includes a plurality of crenellations that exert rotational force on the skin surrounding the lancet puncture site when the lancer is rotated to enhance blood flow from the lancet puncture site.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a lancer for withdrawing a sample of blood from a patient via a lancet. More particularly, the invention is drawn to a lancer for obtaining blood samples from alternate sites, i.e., an arm, leg, or sites other than the fingertip, for the purpose of measuring the concentration of an analyte in blood, i.e., glucose. 
     Conventional lancers on the market are designed to sample blood to determine an analyte in blood such as glucose. These conventional lancers use a finger blood-sampling approach which can be quite painful for the patient because of the concentration of nerves that are present on fingertips. Some companies are developing lancer technology to obtain blood samples from sites other than fingertips (“alternate sites”). Such alternate sites include arms and legs which have a smaller concentration of nerves thus resulting in less pain being associated with the blood sampling process. However, the problem with these alternate sites in that they do not bleed as easily or as well as sites on the finger when pierced using fine gauge lancets. Therefore, there is the need for a new lancer mechanism that can obtain sufficient blood samples from these alternate sites. 
     SUMMARY OF THE INVENTION 
     The present invention is drawn to an improved lancer having features that increase the capability of drawing blood from alternate sites. The present invention forces or milks blood from the lancet puncture on an alternate site by using a twisting motion to act as the mechanism to force blood from the alternate site. During operation, the user activates the lancer to create a lancet puncture in the alternate site, i.e., arm or leg. Once a puncture is created, the user twists the device approximately ¼ of a rotation while the alternate site tip is against the patient&#39;s skin. The user maintains the twisting force for several seconds while fingers, crenellations (castle-like features) or trapezoid features on the alternate site cap grab the skin and apply a twisting motion to the patient&#39;s skin. The twisting motion on the skin causes the puncture wound to bleed at a higher volume than if no twisting is applied. The twisting action is analogous to wringing a wet towel to force water from the fibers of the towel. 
     In addition, the alternate site cap also provides an advantage in that it is removable which allows the user to use the lancer as a conventional lancer when the conventional cap is attached. 
     Another feature of the present invention to enhance blood flow is provided by the new chisel point geometry of the lancet. 
     These and other aspects, features and advantages of the present invention, will become apparent from the following detailed description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view of a lancer device having an alternate site cap tip. 
     FIG. 2 shows an exploded perspective view of the lancer device, the alternate site cap tip, and a conventional adjustable cap tip. 
     FIG. 3 shows an enlarged perspective view of the crenellations (castle-like/trapezoid features) on the alternate site cap tip. 
     FIG. 4 shows a partial cross-section of the alternate site cap tip. 
     FIG. 5 shows a plan view of the lancer device and alternate cap site tip having a lancet within. 
     FIG. 6 shows a perspective view of a lancet according to the present invention. 
     FIGS. 7 and 8 show an enlarged view of the chisel point on the lancet shown in FIG.  6 . 
    
    
     DETAILED DESCRIPTION 
     Lancer devices are typically used to obtain a blood sample from a patient by piercing the skin so that a small amount of blood can be withdrawn. For example, ballistic-type lancer devices are typically designed to be used in conjunction with narrow gauged lancets to obtain a drop of capillary blood from a finger for use in a low-volume blood glucose monitor. The present invention is directed to obtaining a blood sample from an alternate site, i.e., arm or leg, and will draw approximately 0.5 micro-liter of blood. 
     FIG. 1 shows a perspective view of a lancer device  20 . Device  20  has an oblong shaped body  536  having a distal end  501  and a proximal end  502 . Body  536  includes an orifice  516  which provides access to a trigger or button  538  that is used to fire a lancet  300  within device  20 . An end knob  522  extends from proximal end  502  of body  536  and is used to arm device  20  prior to firing the lancet with trigger  538 . An alternate site cap tip  100  is attached to distal end  501  of body  536 . 
     FIG. 2 shows an exploded view of lancer device  20 . Lancer  20  has an oblong outer body section  536  connected to an end knob  522 . End knob  522  is used for arming or cocking the device  20  and is sized to be compatible with the oblong shaped body  536 . Body section  536  suitably has an orifice  516  in which a release means, such as a trigger or button  538 , is mounted. Disposed within body  536  is a plunger or shaft  546 . An alternate site cap tip  100  includes a nose portion  106  with an alternate site tip  104 . 
     In addition, the alternate site cap tip  100  also provides an advantage in that it is removable which allows the user to use lancer  20  as a conventional lancer when a conventional cap tip  508  is attached. FIG. 2 shows a conventional tip assembly  508  having an inner member  502 , outer adjustment member  504 , and nose portion  506 . Conventional tip assembly  508  can be detached from the body assembly  536 . Adjustment member  504  is constrained from linear motion in nose portion  506  and only moves radially. The inner member, also referred to as a lancet stop  502 , has a full thread-form mating into the adjustment member  504 . The user rotates adjustment member  504  radially to change the relative distance between the adjustment member  504  and the lancet stop  502 . The slots  509  interact with posts  201  shown in FIG. 4 to prevent radial motion of stop  502  and permit stop  502  to move only axially due to the camming motion of the thread forms. 
     When armed, yoke latch  539  retains one or more tangs (shown as a single tang  576 ) of plunger  546  in yoke latch window  553 . Yoke latch  539  is mounted to sleeve  586 . Mounting points  598  on yoke latch  539 , which are for example, apertures in yoke latch  539 , attach to posts  504  of sleeve  586 . These mounting points  598  form a pivot axis when yoke latch  539  is actuated. Actuation is achieved by overcoming biasing means  542  to release yoke latch  539 . Yoke latch  539  is pivoted about the pivot axis against biasing means  542 , which is suitably a spring. This causes yoke latch  539  to move perpendicular to the axis of the device  20 , enabling tang  576  on plunger  546  to pass through window  553  of yoke latch  539 . After actuation, proximal fingers  579  on the yoke latch  539  abut distal fingers  581  of the inner knob  524 , thereby preventing engagement of the yoke latch  539  on tang  576  of the plunger  546 . The device can be armed by retracting end knob  522  in the proximal direction since this will cause the distal fingers  581  of inner knob  524  to disengage the yoke latch proximal fingers  579  so that yoke latch  539  can engage tang  576  on plunger  546 . This is accomplished by yoke latch  539  pivoting about the pivot axis to a position in which yoke latch  539  can engage tang  576 . Triggering spring  523  and return spring  526  perform triggering and return functions, respectively. Retainer  528  facilitates retraction of the plunger  546 , members  505  provide support for the posts, and member  525  provides alignment for fingers  581 . 
     FIG. 3 shows an enlarged perspective view of alternate site cap tip  100  with its nose portion  106  and alternate site tip  104 . The present invention uses alternate site cap tip  100  to force or milk blood from the lancet puncture on an alternate site by using a twisting motion to act as the mechanism to force blood from the alternate site. Alternate site tip  104  includes a black dot or measuring indicia  103  or other visual indicators, such as parallel lines separated by the diameter of the blood drop, that the user uses to determine when the proper volume of blood has been extracted. Alternate site tip  104  is transparent so that the user can see the drop of blood that is being drawn and compare it to measuring indicia  103  on alternate site tip  104 . 
     FIG. 3 also shows fingers or crenellations (castle-like/trapezoid features)  101  extending from the distal end of alternate site tip  104  separated by depressions  102  having angle ramp surfaces  102   a  and a curved middle portion  102   b.  The geometry of the distal end of the alternate site tip  104  grabs the user&#39;s skin and by applying approximately a ¼ turn by twisting body  536 , alternate site tip  104  helps milk the lanced site and force blood to come out for testing. The inventors have found that twisting around the circumference of the lancet site produces a higher blood volume compared to conventional methods not using twisting. In addition, the inventors have found that using the twisting method with the alternate site tip  104  of the present invention provides even more blood volume over any other methods and devices currently known. 
     During operation, the user activates lancer  20  to create a lancet puncture in the alternate site, i.e., arm or leg. Once a puncture is created, the user twists body  536  approximately ¼ of a rotation while alternate site tip  104  is against the patient&#39;s skin. The user maintains the twisting force for several seconds while crenellations  101  on alternate site tip  104  grab the skin and apply a twisting motion to the patient&#39;s skin. The twisting motion on the skin causes the puncture wound to bleed at a higher rate than if no twisting is applied. The twisting action is analogous to wringing a wet towel to force water from the fibers of the towel. 
     FIG. 4 is a partial cross-section of the alternate site cap tip  100  again showing nose portion  106  with alternate site tip  104  attached therein. FIGS. 3 and 4 show an aperture  105  through which a stylet  301  on the lancet  300 , shown in FIG. 5, extends to make the lancet puncture upon activation of lancer  20 . FIG. 4 also shows a pair of posts  201  within nose portion  106  that mate with slots  109  in alternate site tip  104  and members  505  that retain alternate site tip  104  within nose portion  106 . FIG. 4 also shows detents  112  that mate with detents  212  on body  536  to hold alternate site cap tip  100  on body  536  during use. FIG. 5 shows a plan view of lancer device  20  with alternate site cap tip  100  removed from body  536 . FIG. 5 also shows lancet  300  mounted within body  536  and having stylet  301  extending therefrom. 
     FIG. 6 shows a complete perspective view of lancet  300  including its shield member  302 . Shield member  302  is suitably used to cover stylet  301  by interfacing with portion  305  of lancet  300 . FIG. 7 shows an enlarged view of a chisel point  310  at the distal end of stylet  301 . This is yet another aspect of the present invention used to enhance blood flow when using an alternate site. The new chisel point geometry of chisel point  310  on lancet  300  includes two planar surfaces  311  joined together at a cutting edge  312 . The inventors believe that using the chisel point  310  of the present invention at an alternate site improves blood flow and provides a sufficient amount of blood to perform blood analyte testing. 
     Other variations and modifications of this invention will be obvious to those skilled in this art. This invention is not to be limited except as set forth in the following claims.