Abstract:
A lancet device for drawing blood from a digit of a patient. The lancet device is particularly directed to a disposable, pre-armed or armable device including an element for constricting the finger or digit of a patient or user from which the blood is to be drawn. The device includes a portion that functions in a tourniquet manner to increase the blood supply in the area where the lancet is to create an incision. The lancet portion and the structure of the device are designed to produce a substantially painless incision in the patient. The biasing elements of the device provide for forcing the lancet portion toward the target area and for retrieving the lancet into the device after an incision has been made. After use in making an incision, the parts of the device that contact the patient&#39;s blood are withdrawn from possible inadvertent contact thus avoiding a chance of contamination of the user with the patient&#39;s blood.

Description:
[0001]    This invention relates to the field of blood-sampling devices, particularly to a disposable, pre-armed or armable lancet device capable of constricting the finger from which the blood is to be drawn.  
           [0002]    For purposes of medical diagnosis it is often necessary for patients to provide small specimens of blood to be analyzed. When it is required that such analysis be performed on a routine basis, as is often the case with patients suffering from diabetes or those diagnosed with the Human Immunodeficiency Virus, patients may have to obtain blood specimens without the help of a nurse or other assistant. Several disposable apparatus allowing patients to collect blood samples without the aid of others are available. Since all such devices obtain the blood by producing a small incision in the skin of the patient (most commonly the skin of one of the digits of the hand) with a sharp lancet, it is imperative that devices of this type be executed in a manner which allows them to be safely disposed after use without risking injury and possible infection to the person who may come into contact with these devices after their disposal. Another desirable feature of instruments for collection of blood samples is the inability of the patient to anticipate the incision and so attempt to withdraw therefrom.  
           [0003]    Even though the makers of known blood-sampling devices have attempted to address the above-mentioned concerns by providing safer and more convienient instruments, prior-art units continue to fall short in several areas. Significantly, prior-art units require the patient (or the assistant to either manually squeeze the blood from the incision or to employ a separate tourniquet for this purpose, thus complicating the procedure and making it more stressful for the patient. Additionally, if the act of squeezing the blood from the incision is manually performed by an assistant who massages the skin around the incision, the contact with the blood of the patient, even when made by the assistant&#39;s hands protected with surgical gloves, presents the assistant with a risk of infection. Furthermore, obtaining a blood sample from the patient&#39;s finger using a conventional lancet device often causes the patient to experience a painful sensation. This occurs when the incision in one of the digits of the patient&#39;s hand is made so that the lancet strikes too close to the bone (e.g. the distal phalanx) of the digit.  
         BRIEF SUMMARY OF THE INVENTION  
         [0004]    It is accordingly desirable to provide a lancet device that operates in a manner to minimize the pain caused by the incision.  
           [0005]    It is desirable to provide a lancet device that increases the efficiency with which blood is collected from the incision without unnecessary discomfort to the patient or additional risk of infection to the assistant gathering the blood sample, if such an assistant is utilized.  
           [0006]    Because lancets and their associated parts are usually considered to be a disposable unit used one time, it is further desirable that the lancet and its associated parts and be easily assembly be inexpensively manufactured.  
           [0007]    Because of the chance of exposure of the user or an assistant to infectious materials, it is desirable that the part of the lancet that contacts such infectious material be withdrawn from open exposure after an incision has been created with the lancet.  
           [0008]    It is desirable that the lancet assembly accomplish a contact with a patient&#39;s digit in a manner that will operate to increase blood supply to the target area where an incision is to be created.  
           [0009]    Further objects and features of the present invention will be readily apparent to those skilled in the art from the appended drawings and specification illustrating preferred embodiments.  
           [0010]    In the embodiments of the invention illustrated herein, the lancet device comprises an adjustable digit-constricting member that is movably and operatively coupled to an outer sleeve. An inner sleeve is movably disposed relative to the outer sleeve. A lanceted plunger is movable within the outer sleeve with the inner sleeve interposed between the outer sleeve and the lanceted plunger. The lanceted plunger is releasably engaged within the inner sleeve and a biasing element biases the lanceted plunger relative to the inner sleeve. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is an exploded perspective of a lancet device in accordance with one embodiment of the present invention.  
         [0012]    [0012]FIG. 2 is a sectional view of the outer sleeve of FIG. 1.  
         [0013]    [0013]FIG. 3 is an assembly of the outer sleeve, inner sleeve and lanceted plunger of FIG. 1  
         [0014]    [0014]FIG. 4 is a sectional view of the hollow cylindrical body of FIG. 1.  
         [0015]    [0015]FIG. 5 is a perspective view of the clamping member of the lancet device.  
         [0016]    [0016]FIG. 6 is a sectional view through the clamping member of FIGS. 5 and 7 taken along the lines  6 - 6  of FIG. 7.  
         [0017]    [0017]FIG. 7 is a bottom plan view of the clamping member of FIG. 5.  
         [0018]    [0018]FIG. 8 is a perspective view of the assembled and armed lancet device of the embodiment of FIG. 1.  
         [0019]    [0019]FIG. 9 is a sectional view of an aternative embodiment of the invention.  
         [0020]    [0020]FIG. 10 is an alternative form of the biasing means for biasing the outer sleeve with respect to the inner sleeve.  
         [0021]    [0021]FIG. 11 is an illustration of the flex position for the biasing means of FIG. 10.  
         [0022]    [0022]FIG. 12 is a sectional view of another alternative form of the invention.  
         [0023]    [0023]FIG. 14 illustrates the retracted position of the lancet in the embodiment of FIG. 12 after an incision has been made. 
     
    
       [0024]    For purposes of illustration, these figures are not necessarily drawn to scale. In all of the figures, same components are designated by the same reference numerals.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In the other instances, well-known elements have not been shown or described to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather that a restrictive, sense.  
         [0026]    An exploded view of the lancet device according to one embodiment of the invention is illustrated in FIG. 1. The device includes a tube  100 , springs  102  and  104 , a lancet holder  106 , a lancet  108 , an outer member  109  comprising a hollow cylindrical body  110  integral with finger rests  112  at its trailing end and a loop  114  at its leading end, and a clamping member  116 .  
         [0027]    As shown in FIG. 2, tube  100  includes an external flange  118  at the trailing end thereof and a collar  120  located along the periphery of the tube. Tube  100  also has a bore  121  and a pair of diametrically-opposed projections  122  (only one of which is apparent from the drawing) formed on the interior of the tube at its trailing end. A pair of diametrically-opposed triangular barbs  124  is positioned on the interior of the tube.  
         [0028]    The particulars of lancet holder  106  are discussed with reference to FIG. 3. The lancet holder has a convex end-face  126  at the trailing end thereof, a first cylindrical section  128 , a second cylindrical section  130 , a third cylindrical section  132 , and a flat end-face  134  at the leading end of the lancet holder. The diameters of section  128  and  132  are substantially equal and are smaller than that of section  130 . End-face  134  includes a cavity  135  in which lancet  108  is mounted in a conventional manner. Cylindrical section  130  is defined by a trailing shoulder  136  and a leading shoulder  138 . Cylindrical section  128  incorporates an annular protuberance  140  and a pair of diametrically-opposed triangular barbs  142 .  
         [0029]    As illustrated in FIG. 4, hollow cylindrical body  110  of outer member  109  has a bore  143  and an interior flange  144  formed inside the bore at the leading end of the cylindrical body. Flange  144  defines an opening  145 , whose diameter is less than the outer diameter of collar  120 . Loop  114  comprises a pair of rails  146 , bridged by an arcuate band  148 .  
         [0030]    [0030]FIG. 5 is a perspective view of clamping member  116 , which includes a curved platform  150  having a centrally-oriented through opening  152  and a countersink  154 , concentric with opening  152 . The diameter of opening  152  is smaller than the radial dimension of section  130  of the lancet holder, but has a clearance fit with section  132  thereof. The curvature of platfrom  150  substantially compliments that of a digit of a human hand. A pair of recesses  156  are provided on the opposite sides of platform  150 . Member  116  also includes a cylindrical neck  158 . FIG. 6, which is a sectional view of member  116 , illustrates that neck  158  contains a counterbore  160 , which communicates with opening  152 . As apparent from FIG. 6 and also from FIG. 7 (bottom plan view of member  116 ), a pair of reinforcing members  162  are located between neck  158  and recesses  156  to enhance the rididity of the clamping member. Counter bore  160  is sized to make the outer surface of tube  100 .  
         [0031]    All the above-described components of the lancet device may be manufactured from injection-molded plastic, except for lancet  108 , which is preferably made of stainless steel or other materials used for surgical appliances. It will be obvious to one of ordinary skill in the art that a variety of materials and manufacturing techniques may be utilized without departing from the scope of the present invention.  
         [0032]    [0032]FIG. 8 is a perspective view of the assembled and armed lancet device of this embodiment. The assembly sequence of the lancet device is described below. As shown in FIG. 1, spring  104  is positined with respect to section  128  of lancet holder  106  such that the leading face of the spring seats against shoulder  136  (FIG. 3) and the leading coil of the spring engages the vertical face of one of barbs  142 . A clearance fit exists between the helical coils of spring  104  and the surface of section  128 . The radial distance between the tips of barbs  142  is less than the diameter of section  130  (FIG. 3), but produces an interference fit with the coils of spring  104 . Therefore, the leading coil of spring  104  must expand sightly as it is forced past the barbs. The expansion of the coil is facilitated by the triangular shape of the barbs, oriented with the oblique surfaces toward the leading end of the spring. Once the leading coil clears the barb tips, it contracts, engaging the vertical face of one of the barbs. The outer diameter of protuberance  140  (FIG. 3) is less than the inner diameter of the helical coils of spring  104 , allowing a clearance fit between the spring and protuberance  140 .  
         [0033]    The assembly comprising lancet holder  106  and spring  104  is then inserted into bore  121  of tube  100  from the leading end of the tube, with lancet  108  facing away from the bore. Cylindrical section  130  of the lancet holder has a sliding clearance fit with bore  121 . Spring  104  also has a clearance fit therewith. At this point, the lancet device may be armed by advancing the holder/spring assembly into the bore of the tube, e.g., with an elongated pushrod (not shown) acting against end-face  134  (FIG. 3), until annular protuberance  140  of the lancet holder interlocks with projections  122  of the tube by virtue of an interference fit. (Alternatively, the arming of the lanced device may be performed after all assembly steps have been completed.) As the lancet holder/spring assembly is advanced into the tube, the trailing coil of spring  140  expands past the oblique portions of barbs  124  (FIG. 2) and engages the vertical face of one of the barbs, whereby the trailing face of the spring becomes seated against projections  122 . Once protubrance  140  engages projections  122 , the pushrod is withdrawn. The tube/lancet holder assembly remains locked in the armed position because the frictional force provided by the interference fit between protuberance  140  and projections  122  exceeds the force exerted by spring  104 , which is compressed between projections  122  and shoulder  136 . It should be noted that protuberance  140  has a clearance fit with triangular barbs  124 .  
         [0034]    Next, rails  146  of loop  114  are slightly deformed outward to allow recesses  156  of clamping member  116  to be positioned, one at a time, along the rails, so that member  116  is free to translate with respect to the rails of the loop. Spring  100  is then placed over the leading end of tube  100  so that it seats against collar  120  and the tube is inserted into the trailing end of the bore of hollow cylindrical body  110 . Collar  120  of the tube has a sliding clearance fit with bore  143  and flange  144  (FIG. 4) has a sliding clearance fit with the peripheral surface of tube  100 . The tube is then advanced into the bore until the leading end of the tube emerges through opening  145  (FIG. 4), causing spring  102  to be compressed between collar  120  of the tube and flange  144  of the hollow cylindrical body. The end of tube  100  protruding through opening  145  is then inserted into counterbore  160  of the clamping member and a coupling therebetween is acheived using conventional methods (e.g., a press-fit, adhesives, ultrasonic bonding, or other known techniques). The values of spring constants and lengths of springs  102  and  104 , the distance between collar  120  and the leading end of tube  100 , and the distance between protuberance  140  and shoulder  136  of the lancet holder are chosen such that even at maximum compression of spring  102  the combined force exerted by springs  102  and  104  is less than that of the friction force between protuberance  140  and projections  122 .  
         [0035]    The assembled and armed lancet device is shown in FIG. 8. In this configuration, spring  102  (not visible in FIG. 8) keeps tube  102  retracted with respect to cylindrical body  110 , so that neck  158  of clamping member  116  is pressed against the outer surface defined by flange  144  of body  110 . It should be understood that spring  102  is provided as a convenience feature only and is not necessary to the operation of the lancet device according to the invention, since tube  102  may be retraced with respect to cylindrical body  110  by other means, e.g., gravity.  
         [0036]    As mentioned above, the lancet may alternatively be armed at this point, i.e., after assembly of all the component parts has been completed.  
         [0037]    To collect a blood sample, a digit  164  of one hand (FIG. 8) is inserted into loop  114  while the patient, or operator, holds the lancet device in his or her other hand with the index and middle fingers covering rests  112  and the thumb pressed against end-face  126  of the lancet holder. The patient then uses the thumb to apply increasing pressure on the end-face  126 , whereby tube  100  and clamping member  116  translate with respect to finger clamp  109  so that digit  164  is compressed between clamping member  116  and band  148  with increasing force. The tourniquet effect produced by the clamping member and the band on the digit of the patient causes the skin of the finger to swell, conforming to the contours of counter sink  154 . Once the digit of the patient has been sufficiently squeezed between clamping member  116  and loop  114  to produce beneficial swelling of its tissue, additional pressure exerted on end-face  126  will overcome the frictional force between protuberance  140  of lancet holder  106  and projections  122  of tube  100 , whereby lancet  108  is discharged and propelled by spring  104  toward the digit. Spring  104  is sized so that when the extension of the spring reached its maximum point, the lancet momentarily protrudes through opening  145  of body  110  and pierces the skin of the finger, producing an incision of a desired size and shape (in accordance with the size and shape of the lancet). As the incision is being made, the level of discomfort experienced by the user is minimized due to beneficial swelling of the tissues at the point of the incision, which prevents the lancet from striking too close to the bone of the digit. The above-mentioned swelling results from the tourniquet action produced by member  116  and loop  114  and is augmented by the presence of countersink  154 , which promotes the swelling of the tissue directly around the point of the incision.  
         [0038]    Upon making the incision, lancet  108  is permanently retracted into bore  143  by spring  104 , which contracts to its equilibrium position. Spring  104 , opposite ends of which remain attached to barbs  124  of tube  100  and barbs  124  of lancet holder  106 , ensures that the tip of lancet  108  remain below the surface of platform  150 . Since the construction of the lancet device is such that the instrument cannot be disassembled and re-armed (in its preferred use), the device may at this point be safely disposed without risking injury and infection to individuals who may come into contact with the lancet device.  
         [0039]    Once the incision has been made, pressure on end-face  126  is released removing the compressive force of loop  114  and member  116  on the finger. The loop can then be moved farther back along the finger and pressure on the finger may be reapplied by once again pushing on end-face  126 . The re-tightening of the clamping member and the loop around the finger causes blood to be forced out of the puncture previously made by the lancet, and allows multiple drops of blood to be collected for analysis.  
         [0040]    [0040]FIG. 9 is a sectional view through an alternative embodiment of the present invention. In this embodiment the outer sleeve  900  includes the means in the form of a loop  902  for restraining the finger or digit of the patient. An inner sleeve  908  is movably disposed relative to the outer sleeve  900  and within the outer sleeve. The inner sleeve  908  is coaxially interposed between the outer sleeve  900  and a depressible lanceted plunger  920 . The lanceted plunger  920  is formed with outwardly projecting ears  914  and the inner sleeve is formed with inwardly projecting ribs  924  that cooperate with each other to restrain the plunger  920  in its armed position and to permit release of the plunger for movement within the inner sleeve  908 , as will be described. The plunger  920  is formed with an upper shoulder  921  and a coil spring biasing means  934  engages the upper side of the shoulder  921  and the lower side of the projecting ribs  924  as a means for biasing the lanceted plunger  920  relative to the inner sleeve  908 . A lancet  930  is attached to the lower end  928  of the plunger and extends the desired distance to accomplish the desired incision in a finger or digit.  
         [0041]    The inner sleeve  908  is biased within the outer sleeve and away from the loop portion  902  when this embodiment is assembled. The lower end of the inner sleeve  908  includes outwardly extending ribs  910  the are constructed to engage the inner lower end of the outer sleeve  900  where the loop portion  902  attaches to the outer sleeve  900 . These ribs  910  are designed to be flexible enough to pass into the inside of the outer sleeve and pass into the loop portion and them become stopped as the inner sleeve is biased out of the inner sleeve. The biasing force between the inner sleeve  908  and the outer sleeve  900  is provided by spring  932  that operates between the upper inner surface of the outer sleeve at the outwardly extending ribs  912  at the upper outer surface of the inner sleeve  908 .  
         [0042]    The lanceted plunger  920  is biased within the inner sleeve in a stored position by spring  934 . The spring  934  provides the force needed to project the lanceted plunger to make an incision in a digit held within the loop  902 . When the plunger is released, as will be described hereinafter, the spring forces the plunger through the inner sleeve. The plunger  920  is provided with an extending rib  936  spaced a small distance from the upper shoulder  921 ; this rib  936  engages the lowermost coil of the biasing spring  934  to return the plunger to a relaxed position within the inner sleeve  908  after the lancet has been forced from its cocked position. The upper coil of the biasing spring  934  is retained at the upper end of the inner sleeve  908  by engagement with ribs extending inwardly from the inner surface of the inner sleeve  908 .  
         [0043]    In operation of this embodiment of the invention, the assembly is as shown in FIG. 9 with the lanceted plunger  920  held in a cocked position by the engagement of the ears  914  with the ribs  924  and the bias of spring  934  prepared to force the plunger through the inside of the inner sleeve upon release of the ear/rib engagement. As the user grips the outer sleeve at the finger rests  904  and  906  and presses the inner sleeve downwardly into the outer sleeve  900 , the lower end of the inner sleeve engages the digit captured within the loop  902  and creates the desired compression of the digit as has been previously described. Further force against the inner sleeve  908  by pressing on the extension  926  of the upper end of the plunger  920  causes the plunger to pass through the ear/rib engagement and to release the bias of the spring  934  to force the plunger  920  downwardly and to cause the lancet  930  to pierce the digit when at its fullest extension. After piercing the digit the bias of spring  934  returns the plunger to the stored position within the inner sleeve  908  and with the lancet end drawn into the sleeve. When the user&#39;s force is removed from forcing the inner sleeve into the outer sleeve, the bias of spring  932  returns the inner sleeve  908  into its withdrawn position within the outer sleeve  900 . The lancet device is not reusable because the bias of spring  934  has been released and the plunger cannot be forced out of the inner sleeve  908 .  
         [0044]    [0044]FIG. 10 illustrates an alternative form for the biasing means for the engagement of the inner sleeve  908  against a digit retainded within the loop  902 . In this form, the bias between the outer sleeve  900  and the inner sleeve  908  is provided by a leaf spring like assembly  950  that engages the upper surface of the finger rests  904 / 906  at one end and the extension  926  of the inner sleeve  908 . The internal bias of the lanceted plunger within the inner sleeve in this embodiment may be the same as that described with respect to FIG. 9 with the upper extension movement toward the outer sleeve  900  causing the lower end of the inner sleeve  908  to engage the digit within the loop and the eventual release of the lanceted plunger to make the incision in the digit. The inner sleeve is withdrawn as is the case in FIG. 9.  
         [0045]    The leaf spring assembly includes a ring portion  952  that encloses the upper end of the extension  926 . The extension has a first set of radially extending ears  954  near its upper end and a second set of extending ears  956  below the upper ears and along the body of th3 dextension  926 . The ring portion passes over the first set of ears to place the lancet device in its position for use and over the lower set of ears after use. The upper ears cooperate with the ring portion  952  when the lancet device is in its cocked position and the lower ears cooperate with ring to return the inner sleeve to a stored position after use.  
         [0046]    [0046]FIG. 11 illustrates the position of the leaf spring assembly prior to release of the inner sleeve and the lanceted plunger.  
         [0047]    [0047]FIGS. 12 and 13 illustrate another alternative embodiment of the present invention. This embodiment uses a single spring for the force to send the lanceted plunger to its incision position and for return of the plunger and lancet to the stored positin. In these FIGs the outer sleeve  900  includes the finger or digit loop  902  (here shown as rectangular) and encloses the inner sleeve  908  in slideable engagement. The inner sleeve  908  has, at the lower end, inwardly extending ribs  960  and outwardly extending ribs  962  and, at the upper end, inwardly extending ribs  964 . A lanceted plunger  920  is slideably enclosed within the inner sleeve  908 .  
         [0048]    The plunger has a lancet  930  extending from its lower end and has a operator extension  926  from its upper end.  
         [0049]    A single biasing spring is operational within the inner sleeve to bias the lanceted plunger for release to create an incision and for return of the plunger to a stored position. The biasing spring  970  includes three integral portions. An upper portion  970 A circles the plunger above the shouldered portion  921  and engages the lower edges of the ears  964  extending inwardly from the inner sleeve  908 . The middle portion  970 B circles and engages the shoulder portion of the plunger; the engagement may be in grooves in the exterior surface of the shouldered portion  921 . The lower portion  970 C circles the lower entension of the plunger and extends beyond the distance of the lancet extension from the plunger.  
         [0050]    In use this embodiment is assembled with the biasing spring aligned with the three sections of the lancet plunger and that subassembly is inserted into the inner sleeve  908  with the extension  926  passing through the upper end of the inner sleeve and engaging its lower shoulders against the inwardly extending ears  964  of the inner sleeve  908 . When in that position, the upper end of the spring  970 A is compressed between the upper end of the shoulder  921  and the inner surface of the ears  964 , the middle portion  970 B of the spring is engaged with the middle portion of the shoulder  921  of the plunger  920 , and lower end  970 C of the spring  970  is circling the lower end of the plunger and the lancet  930 . When ready for use, the lancet device is positioned with the finger of a patient within the restraining loop  902  and the operator engages the finger rests  904 / 906  and the extension  926  to move the inner sleeve into the engage position with the contained digit. Further depression of the extension  926  causes the upper end to pass into the inner sleeve  908  and to release the biasing force of the portion  970 A of spring  970  thus causing th lanceted plunger to move rapidly toward the enclosed digit and to cause the lancet  930  to penetrate the digit causing the desired incision. After the incision has been made, the lower portion  970 C of the spring  970  pushes against the inwardly extending ears  960  of the inner sleeve  908  and retrieves the lanceted plunger into a stored position in the inner sleeve. FIG. 13 illustrates the stored position of the lancet plunger  920  after the device has been used.  
         [0051]    The foregoing has described several embodimnets of a lancet device for drawing blood samples. The lancet device includes an outer sleeve, means for restraining a digit or member of a patient relative to the outer sleeve, an inner sleeve movably disposed relative to the outer sleeve, a depressible lanceted plunger, the inner sleeve is cooaxially interposed between the outer sleeve and the lanceted plunger, means for releasably engaging the lanceted plunger with the inner sleeve, and means for biasing the lanceted plunger relative to the inner sleeve.  
         [0052]    While certain preferred embodiments of the invention have been specifically disclosed, it should be understood that the invention is not limited thereto as many variation will be raedily apparent to those skilled in the art and the invention is to be given it broadest possible interpertation within the terms of the following claims.