Abstract:
Disclosed is an apparatus and method for guiding a needle into a blood vessel of a patient. The apparatus is removably attached to a patient&#39;s arm, and uses the returns from transducer arrays to locate the blood vessel. The needle, positioned on the apparatus, is maneuvered in accordance with the transducer returns to ensure accurate penetration of the blood vessel.

Description:
FIELD OF THE INVENTION 
     This invention relates to the field of medical care and more specifically to an apparatus and process for locating a blood vessel in a person and assisting in inserting a needle into the vessel. 
     BACKGROUND OF THE INVENTION 
     Medical professionals presently locate a blood vessel by palpitation or by blocking circulation in the vessel downstream from the needle insertion point, then looking for the bulging vessel. In many cases this procedure is unsuccessful in locating the vessel. Medical professionals may repeatedly stick the patient until they locate the vessel. Often, even when the vessel is successfully located, the needle penetrates too deeply, penetrating both walls of the vessel and striking a nerve. This problem is particularly acute when the patient is a small child. Or, a located vessel has a tendency to rotate or roll away from the needle as the medical professional attempts to insert it, further complicating the procedure. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to a needle insertion guide apparatus that substantially obviates one or more of the problems due to limitations and disadvantages of the prior art. For example, the needle insertion guide assists in accurately locating a blood vessel within a patient. Thus, a medical professional need only penetrate the patient&#39;s skin once with a needle. Moreover, the needle insertion guide ensures proper alignment of the needle such that only one wall of the blood vessel will be penetrated. Also, consistent with the present invention, a rotatable vessel holder ensures that the blood vessel will not move during insertion of the needle. 
     To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described, a guide for locating a blood vessel in a patient and guiding a needle consistent with the present invention includes a main support housing, means for removably securing the main support housing to the patient, a plurality of transducers attached to the main support housing for transmitting and receiving signals for locating the blood vessel, and at least one needle support attached to the main support housing. 
     To further achieve these advantages, a method for locating a blood vessel in a patient and guiding a needle into the located blood vessel is provided, the method includes the steps  3  of removably securing a main support housing to the patient, energizing a plurality of transducers attached to the main support housing for transmitting and receiving signals, locating the blood vessel based on the signals, and guiding a needle into the patient. 
     The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
     Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description or may be learned by the practice of the invention. The objectives or other advantages of the invention will be realized and attained by the needle insertion guide particularly pointed out in the written descriptions and claims hereof, as well as in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an isometric view of the needle insertion guide; 
     FIG. 2 is an exploded view of the needle insertion guide; 
     FIG. 3 is a wire-frame exploded view of the needle insertion guide; 
     FIG. 4 illustrates a display showing aft transducer data consistent with the present invention; 
     FIG. 5 is a front view of the transducers and securing strap of the needle insertion guide; and 
     FIG. 6 illustrates a display showing transducer pair data consistent with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Reference will now be made in detail to the present preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used to refer to the same or like parts. 
     A needle insertion guide  10 , illustrated in FIGS. 1-3, aids in inserting a needle into a vessel  11 . Needle insertion guide  10  includes a lateral slide  15  and a main support housing  20 , which are secured to a patient by a securing strap  25 . Securing strap  25  can be a flexible strap made of, for example, nylon, which is closed with Velcro®, snaps, etc., and can be of variable lengths to attach to different parts of the patient. Securing strap  25  can also have a fixed shape, such as a metallic or plastic bracelet. 
     Lateral slide  15  has a lateral channel  16  into which lateral guide  26  of main support housing  20  fits. Although lateral channel  16  is shown as a dovetail-shaped channel, any configuration that would maintain lateral guide  26  in the channel would be acceptable. Lateral slide  15  also has a screw  17  that fits into the side of lateral slide  15  and into hole  27  of lateral guide  26 . 
     Main support housing  20  includes two transducer arrays  21  and  22  in transducer array supports  23  and  24 . Transducer array  21  is made up of transducers  40 ,  41 ,  42 ,  43 , and  44 . Transducer array  22  is made up of transducers  50 ,  51 ,  52 ,  53 , and  54 . Main support housing  20  also has two needle supports  28  and  29 . Needle support  28  fits into needle channel  30 . Detent  31  in channel  30  allows needle support  28  to be locked in different positions in needle channel  30 . Housing  20  also has an afl transducer  32 , and a V-block  33  that is rotatably mounted on shaft  35 . A ball detent  34  allows V-block  33  to be locked into place. 
     A computer (not shown) is linked to needle insertion guide  10  and causes signals to be sent and received from aft transducer  32  and the transducers in transducer arrays  21  and  22 . The computer processes and displays information to aid in the positioning of needle insertion guide  10 . It can be linked to guide  10  by cables, by radio link, or by any other suitable means. Alternatively, computing and display capabilities could be built into insertion guide  10  itself. 
     In operation, needle insertion guide  10  is initially placed on, for example, the arm of a patient with transducer arrays  21  and  22  pointing in the direction of the patient&#39;s elbow. Needle insertion guide  10  is positioned with a center line  36  of main support housing  20  roughly lined up with vessel  11 , and then secured to the patient&#39;s arm with securing strap  25 . Guide  10  is then set at its starting positions: needle support  28  in needle channel  30  is positioned at the center of its travel, and lateral guide  26  is positioned in the middle of its travel in lateral channel  16 . 
     To begin locating vessel  11  in the patient, the computer energizes aft transducer  32  to transmit and receive sonic energy. Although aft transducer  32  is shown positioned behind needle support  39 , it could be positioned anywhere along the centerline of main support housing  20 . The computer receives and processes the signals received by aft transducer  32 . The computer then displays data that is monitored by the person operating guide  10 . While monitoring the data, the user moves lateral guide  26  in lateral channel  16  by turning screw  17  until the signal received by af transducer  32  peaks. At this point, guide  10  is positioned coarsely above vessel 
     FIG. 4 illustrates one example of the type of data the computer could display while the user laterally orients main housing  20 . In this embodiment, the display consists of a bar graph showing the magnitude of the signal received by aft transducer  32 . Alternatively, the computer could display the data in various other formats, such as numerically, or any other format that indicates when the signal received by aft transducer  32  has peaked. 
     In order to further define the location and depth of vessel  11 , the computer energizes transducers  40 - 44  and  50 - 54  in transducer arrays  21  and  22 . Each transducer in array  21  has a corresponding transducer in array  22  (e.g., transducers  40 ,  41 ,  42 ,  43 , and  44  in array  21  correspond to transducers  50 ,  51 ,  52 ,  53 , and  54  in array  22 , respectively). FIG. 5 shows a front view of transducer arrays  21  and  22 . As shown, each pair of transducers is aligned such that the centerlines of sonar radiation intersect at specific depths beneath the patient&#39;s skin. Thus, transducers  40  and  50  radiate sonar energy along their respective center lines, which intersect at a point  49 . Similarly, transducers  41  and  51  intersect at point  48 ; transducers  42  and  52  at point  47 ; transducers  43  and  53  at point  46 ; and transducers  44  and  54  at point  45 . Each of the intersections are preferably spaced apart approximately the diameter of vessel  11 . 
     The output of the pairs of transducers are used to fine-tune the location of needle centerline  18  with respect to vessel  11 . This is accomplished by observing the level (e.g., as shown in FIG. 6, described below) of the returned signals in, for example, transducer  42  versus the level of transducer  52 , and then turning screw  17  until the levels are equal. 
     The signal returns are also used to set the longitudinal position of needle support  28  in needle channel  30 . To accomplish this, the computer compares the signal returns from each pair of transducers, and delineates the pair with the maximum signal return. As shown in the wire-frame drawing of FIG. 3, needle support  28  has five detent locks  55 - 59  that allow it to be locked into five different positions by detent  31 . Each of the five positions corresponds to an intersection point of a transducer pair. Specifically, detent locks  55 - 59  correspond to points  45 - 49 , respectively. 
     The person operating needle insertion guide  10  locks needle support  28  into the position corresponding to the maximum signal return from the transducer pairs. FIG. 6 illustrates one example of the type of data the computer could display while the user adjusts needle support  28 . In this embodiment, the display consists of a bar graph showing the magnitude of the signals received by the transducer pairs. As shown, the pair made up of transducers  42  and  52  has the maximum signal returns. Since the signals generated by this pair intersect at point  47 , needle support  28  would be locked at corresponding detent lock  57 . As before, the computer could display the data in various other formats that indicate which transducer pair has the maximum signal return and, thus, which position needle support  28  should be locked in. The computer could also provide instructions to the user at each step. 
     At this point, needle insertion guide  10  is accurately aligned with vessel  11 . To hold the vessel in place, V-block  33  may be rotated downward into contact with the skin. The sides  37  and  38  of V-block  33  hold the vessel, preventing it from moving laterally during the needle insertion process. Detent  34  is used to lock V-block  33  into place. 
     Now, the centerline  18  of a needle placed on needle supports  28  and  29  aligns with the point of intersection of the transducer pair having the maximum signal return. The needle is then moved forward to insert its point into vessel  11 . The geometry of the arrangement ensures that the length from the needle point toothe stop surface on the needle body and the distance from the center of vessel  11  below the skin to the stop surface  39  on needle support  29 , are the same. Thus, insertion will penetrate one wall of vessel  11 , but not the second. 
     This needle insertion guide provides the maximum assurance that vessel  11  will be located on the initial attempt at insertion of the needle and will penetrate it to the proper depth. It will be obvious to those skilled in the art that various modifications and variations can be made in the needle insertion guide of the present invention without departing from the spirit or scope of the invention. For example, different kinds or quantities of transducers, or sensors, at different locations would accomplish the same effect as the preferred embodiment described above. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.