Abstract:
A cannula guide device that can provide a secure and safe transfusion treatment is disclosed, comprising a cannula assembly and a needle assembly. The cannula assembly includes a cannula and a cannula holder, and the needle assembly includes a guide needle and a needle holder. The cannula guide device is characterized in that a rotary cannula arrangement is provided to steadily send the cannula relative to the guide needle toward a patient without generating a repulsive force on the needle holder to avoid pulling out the guide needle accidentally.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to a cannula guide device. More particularly, this invention relates to a cannula guide device that can securely and safely guide a cannula into a blood vessel or tract of a patient without accidental removal of its already pricked guide needle from the patient&#39;s blood vessel or tract, or without undue damage to the patient&#39;s blood vessel or tract or skin by the guide needle, or without undue pains to the patient. 
     2. Prior Art 
     It is generally time consuming to perform blood transfusion or fluid transfusion on a patient. Before, a patient was required to undergo a long and often painful fluid transfusion treatment with a conventional injection needle to be inserted into his or her blood vessel or tract. The patient had to stay substantially motionless during the long transfusion treatment in order to prevent the injection needle from accidentally coming off his or her blood vessel or tract. If the injection needle accidentally comes off, the injection needle must be pricked into the patient again. The patient&#39;s awkward movement might additionally cause damage onto his or her blood vessel or tract or even skin with the sharp needle end, which would inevitably accompany considerable pains to be suffered by the patient. 
     Cannula guide devices have been introduced in replacement of such conventional injection needle devices so as to perform safer and securer and thus less painful fluid transfusion on a patient who needs transfusion treatment, to a great benefit not only to the patient but also to the medical personnel who performs the transfusion treatment upon the patent. 
     A conventional cannula guide device is comprised of a needle holder, a cannula and a guide needle axially secured to the needle holder. The guide needle is provided through the fluid passage of the cannula with its forward or distal end protruding a few millimeters from the distal end of the cannula so as to be pricked ahead of the cannula into a patient&#39;s blood vessel or tract hypodermically. The cannula is then pushed or pulled and slid forward or distally on the axially provided internal guide needle into the blood vessel or tract. When the distal end of the cannula is pricked or inserted into the blood vessel or tract, the guide needle is pulled rearward or proximally and removed from the blood vessel or tract and eventually from the cannula entirely in order to clear the fluid passage of the cannula for transfusion treatment. Blood or fluid is then pumped into or extracted from the blood vessel or tract through the fluid passage of the cannula. 
     Such a conventional cannula guide device provides an invaluable benefit to patients who need transfusion treatment as well as medical personnel who perform transfusion on such patients, but not without a serious shortcoming. The shortcoming that inevitably accompanies conventional cannula guide devices is described hereinunder using the accompanying FIG. 5 (prior art), in which a cannula guide device  80  is shown comprising a cannula  61 , a guide needle  71 , a cannula base  70   b , and a needle holder  70   a . The guide needle  71  is provided through the fluid passage (not shown) formed through the cannula  61 . The rear or proximal end of the cannula  61  is secured to the forward or distal end of the cannula base  70   b.    
     After the guide needle  71  is pricked into a blood vessel or tract  90  of a patient (not shown) a couple of millimeters deep, the cannula guide device  80  is generally held with four fingers as shown in FIG.  5 . The cannula base  70   b  is held between a thumb and index finger of one hand, while the needle holder  70   a  is held between the other thumb and index finger. The cannula  61  is pushed (or pulled) forward or distally in the direction shown by an arrow F 1  to be inserted into the blood vessel or tract  90  where the guide needle  71  has been pricked, while the needle holder  70   a  is carefully held still. Otherwise, the needle holder  70   a  may be inadvertently pulled rearward or proximally in the direction shown by an arrow F 2  as a reaction, which would pull the pricked guide needle  71  inadvertently out of the blood vessel or tract  90 , and may cause damage on the blood vessel or tract  90  or the patient&#39;s skin. Such can likely happen when the medical performer is pressed for time. The guide needle  71  must be pricked into the blood vessel or tract  90  over again, to the physical as well as mental detriment of the patient, which would be equally detrimental to the medical performer. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an improved cannula guide device that can safely and securely insert its cannula into a patient&#39;s blood vessel or tract without generating awkward reactive force on its needle holder and guide needle. 
     The above object of the invention can be achieved by providing a rotary cannula arrangement that can rotate and advance its cannula on the axially provided guide needle instead of pushing or pulling the cannula. 
     Such a rotary cannula arrangement is provided such that the cannula holder is rotated with a finger or fingers of one hand coaxially with the needle holder in a prearranged direction relative to the needle holder so as to gradually and steadily advance the cannula on the guide needle into a patient&#39;s blood vessel or tract, while the needle holder is held substantially motionless with the other hand. There will hardly be caused “reactive motion” on the needle holder for the cannula is not pushed or pulled forward or distally. Accordingly, accidental detachment of the guide needle from the patient&#39;s blood vessel or tract can be effectively avoided. 
     The foregoing feature of the invention may be provided by providing the distal end of the needle holder with a slant surface and the proximal end of the cannula holder with a protrusion to be turned and slid along the slant surface forward, while adequately preventing accidental detachment of the needle holder and the cannula holder from each other. With this arrangement, the cannula holder and cannula can advance forward relative to the needle holder and the guide needle without “kicking back” the needle holder when the cannula holder is coaxially rotated by means of the protrusion relative to the needle holder, as will be described hereinafter in more detail referring to the accompanying drawings. 
     Such a feature of the invention may alternatively be provided by providing a thread mating arrangement between the needle holder and the cannula holder, as will be described in detail hereinafter using the accompanying drawings. The cannula whose proximal end is coaxially secured to the distal end of the cannula holder gradually and steadily advances on the guide needle as the cannula holder advances, without generating reactive force on the needle holder. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG.  1 ( a ) shows a cannula guide device according to an embodiment of the present invention; 
     FIG.  1 ( b ) shows the cannula guide device of FIG.  1 ( a ), where the cannula and cannula holder are dismantled; 
     FIG.  1 ( c ) shows the dismantled cannula and cannula holder; 
     FIG. 2 is an enlarged front view of the cannula guide device; 
     FIG. 3 is a longitudinal sectional view of the cannula guide device; 
     FIG.  4 ( a ) shows an alternative cannula guide device according to another embodiment of the present invention; 
     FIG.  4 ( b ) shows the cannula guide device of FIG.  4 ( a ), where the cannula and cannula holder are removed; 
     FIG.  4 ( c ) shows the removed cannula and cannula holder; and 
     FIG. 5 shows a conventional cannula guide device and an example use. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     In FIG. 1 is shown a cannula guide device  50  according to an embodiment of the present invention. The cannula guide device  50  is comprised of a needle assembly  20  and a cannula assembly  10 . The needle assembly  20  is comprised of a guide needle  21  and a generally cylindrical needle holder  22  having a conical needle base  22   c  on its distal end. The cannula assembly  10  is comprised of a cannula  11  and a generally conical cannula holder  12  having a conically formed opening which faces rearward. The cannula holder  12  is provided with a plate-like protrusion  13  on its outer surface as shown in FIG.  2 . The protrusion  13  may take any suitable configuration as long as it provides a “protrusion” large enough to sufficiently catch a finger and slide on the slant surface  23  (to be described) without slipping off. The guide needle  21  is coaxially secured on the conical needle base  22   c.    
     The needle holder  22  is additionally provided with a receptacle  22   b  enclosed with a circumferential wall  22   a  whose diameter is considerably larger than that of the cylindrical portion of the needle holder  22 . The receptacle  22   b  houses the conical needle base  22   c  and receives the proximal end of the conical cannula holder  12  to be capped on the conical needle base  22   c , the conical opening  12   b  accommdating the needle base  22   c . The receptacle  22   b  is provided on its distal portion with a slant surface  23  in order to provide the cannula holder  12  with a gradual forward movement when the protrusion  13  is hooked and turned with a finger of a transfusion performer and slid on the slant surface  23  forward as can be readily appreciated by a person skilled in the relevant art. 
     The conical cannula holder  12  is provided with an axial fluid passage  12   c  in fluid communication with the cannula  11 , which is widened and conically shaped near its proximal opening to provide the aforementioned conically formed opening such that the widened passage portion can properly mate with and securely seat itself on the conical needle base  22   c  as described earlier. 
     The cannula guide device  50  of the present invention is utilized as follows. The guide needle  21  is inserted through the cannula holder  12  and the cannula  11  from the proximal end of the cannula holder  12  till the distal end of the guide needle  21  protrudes a few millimeters from the distal end of the cannula  11 . The cannula holder  12  is mounted on the needle base  22   c  as described earlier such that the protrusion  13  is seated at the proximal end of the slant surface  23 . The exposed distal end or tip of the guide needle  21  is pricked into a blood vessel or tract of a patient (not shown) through the skin of the patient by sending the needle holder  22  forward carefully relative to the cannula holder  12  and cannula  11  which are to be held stationary. 
     Next, the distal end of the cannula  11  is guided into the blood vessel or tract of the patient utilizing the above-described feature of the present invention. When the cannula holder  12  is turned with a finger of one hand utilizing the protrusion  13  toward the distal end of the slant surface, the protrusion  13  slides along the slant surface  23  toward the distal end of the slant surface  23 , gradually sending the cannula holder  12  and the cannula  11  forward. The needle holder  22  is simply held stationary with the other hand. There is no need to reactively pull the needle holder  22  proximally. Therefore, accidental removal of the guide needle  21  from the blood vessel or tract is adequately prevented until the cannula  11  is properly seated in the blood vessel or tract. 
     The guide needle  21  of the cannula guide device  50  is generally made of stainless steel, and the cannula  11  is generally made of soft resin material such as polyethylene. The needle holder  22  and the cannula holder  12  are generally made of rigid resin material such as polyurethane or polypropylene. However, as will be appreciated by a person skilled in the relevant art, any appropriate materials can be utilized to provide the foregoing members. Advantageously, a smoothing agent such as stearic acid is added to the cannula holder and/or the needle holder materials to decrease the friction or promote the sliding property between them. 
     FIG. 4 shows an alternative cannula guide device  50  of the present invention. This cannula guide device  50  is comprised of a needle assembly  20  and a cannula assembly  10  as the foregoing embodiment. The needle assembly  20  is comprised of a guide needle  21  and a generally cylindrical needle holder  22 . The cylindrical needle holder  22  is provided on its distal end with a needle base  22   c  where the proximal end of the guide needle  21  is secured. The needle base  22   c  is provided with a thread  24  on its outer surface. The cannula assembly  10  is comprised of a cannula  11  and a cannula holder  12  which has a threaded receptacle  14  that can mate with the thread  24  of the needle base  22   c.    
     The use of this cannula guide device  50  is practically identical with that of the previously introduced cannula guide device except that the cannula holder  12  of this embodiment engages the needle base  22   c  in a “bolt-nut” manner. As will be easily appreciated, the cannula holder  12  and the cannula  11  are gradually and steadily sent forward relative to the guide needle  21  into a blood vessel or tract of a patient as they are turned with fingers of a medical performer in the thread loosening direction, while the needle holder  22  is held stationary. It is not required to reactively pull the needle holder  22  proximally. The tip of the guide needle  21  can safely and steadily stay in the blood vessel or tract of the patient while the cannula  21  is being sent into the blood vessel or tract of the patient. 
     It is to be appreciated that the foregoing embodiments are only for illustration of the present invention. Accordingly, modifications or changes can be made to the invention without departing from the teachings of the present invention. The scope of the invention is only to be limited as necessitated by the accompanying claims.