referring to fig1 it can be seen that the present invention is composed of three main components , a finder needle 1 , a catheter support tube 2 , and a catheter 3 . the catheter support tube is hereinafter referred to as simply the support tube . all three main components contain a centrally located , longitudinal hollow passageway or lumen and all three are positioned about the central longitudinal axis of the finder needle . in this position , the finder needle fits within the support tube and can be advanced through the support tube &# 39 ; s passageway to have its tip 1e extend beyond the support tube , as can be seen to the right in fig1 . similarly , the support tube fits within the catheter and can be advanced through the catheter passageway to have its tip 2a extend beyond the catheter , which also can be seen to the right in fig1 . the longitudinal passageway or lumen in the catheter 3 is designated by drawing numeral 3p and can be seen in the cross sectional view of the catheter shown in fig2 . the longitudinal passageway or lumen in the support tube 2 is designated by drawing numeral 2p and can be seen in the cross sectional view of the support tube illustrated in fig3 . the finder needle , support tube and catheter all have their own individual hubs which are designated by drawing numbers 1b , 2b , and 3b respectively . these , hubs which can be seen to the left in fig1 form the left hand termination of these three components . attached to the left hand side of the finder needle hub 1b is a syringe 4 used to draw blood through the finder needle when a selected vein has been penetrated . in one embodiment of the present invention , wings 3w are attached at the proximal end of the hub 3b and extend radially outward of the hub as shown in fig5 to facilitate manipulation of the catheter by a physician . extending above the support tube hub is a support hub pin 2e used for the finder needle automatic latch , which is part of a safety mechanism used to latch the finder needle within the support tube after its withdrawal from the assembly . this safety mechanism is described below in connection with the detailed description of fig3 . extending above the catheter hub is a catheter hub pin 3e used to control an automatic blood flow shut off valve , which is a second safety device used to automatically shut off the flow of blood when the support tube is withdrawn from the assembly . this second safety mechanism is described below in connection with the detailed description of fig4 . the finder needle and the catheter both have graduation marks , designated 1d and 3d respectively . these marks are first used to measure the depth of penetration to a selected vein by the finder needle and then used again to set the depth of penetration of the catheter to bring it to the same depth as the finder needle when the finder needle penetrated the selected vein . the use of these graduation marks helps to insure that the catheter has reached and penetrated the selected vein . in the use of the assembly shown in fig1 the finder needle 1 is advanced through the support tube 2 and the support tube is similarly advanced through the catheter until the hubs of these components are in contact . in this position , the finder needle is exposed and extends to the right well beyond the support tube , as can be seen in fig1 . the finder needle , which has a sharp tip 1e , is then inserted into the patient in the direction in which a selected vein is expected to be located . once the selected vein is located , blood can be easily drawn into a syringe 4 which is connected to the left or proximal end of the finder needle as shown in fig1 . the catheter with the support tube positioned firmly inside are then advanced together to the selected vein using the finder needle as a guide . the support tube has a tip 2a , which although not as sharp as that of the finder needle , is sufficient to widen the opening to the vein made by the finder needle so that the support tube and the catheter can pass through the tissue to the selected vein and then penetrate the selected vein . during the advancement of the catheter to the selected vein , the support tube , which is typically made of steel and positioned immediately beneath the catheter , stiffens the catheter by providing support , thereby preventing the otherwise flexible catheter from binding or bunching during insertion . once the catheter has entered the selected vein , the finder needle and the support tube are withdrawn from the rear of the assembly , leaving the catheter in the selected vein . the catheter , which is formed from a flexible plastic tube that was temporarily stiffened by the support tube during the insertion procedure , is again flexible because of the withdrawal of the support tube . this flexibility of the catheter prevents injury to the vein and the surrounding tissue because there is no longer a rigid and heavy assembly , comprising the support tube , finder needle and their hubs , extending out of the patient . the weight of this assembly , if not strapped in place , would tend to tip over and cause such injury . even if this assembly were taped in place , it could be hit inadvertently during the placement of other lines . withdrawal of the finder needle and the support tube avoids such problems . the catheter is typically dress over and onto the patient and then taped in place , thereby providing a low profile connection to the selected vein with little pressure on the surrounding tissue and a greatly reduced possibility of injury . in one embodiment of the present invention , the support tube is tapered down from the proximal or left end to the distal or right end as shown in fig2 with the widest diameter of the support tube being at the end 2c near the hub 2b and the smallest diameter being at the tip 2a . this configuration of the support tube prevents the catheter from sliding back over the support tube when the catheter and support tube are being advanced toward the selected vein . before this configuration can be use with a patient , the support tube must first be advanced through the catheter under sufficient pressure to slightly expand the catheter at its hub end . this forced expansion of the catheter causes the catheter to be held with sufficient pressure about the support tube to prevent the catheter from moving relative to the support tube as the two are advanced together through the tissue to the selected vein . once the catheter is placed in the vein , the catheter is held at its hub end and the support tube is withdrawn . holding the catheter hub prevents the catheter from moving back with the withdrawal of the support tube . once the hold between the support tube and the catheter is released in this manner , the support tube can continue to be withdrawn without difficulty because the support tube taper leaves only the reduced diameter portion of the support tube in the catheter . referring again to fig1 it can be seen that this figure shows a rigid lateral tube 5 extending from a side of the catheter hub . within the tube 5 is a medication control valve 3s which is actuated by an adjustment knob 7 . the valve 3s is shown in the cross sectional view of fig4 . the knob 7 can be seen to be connected to one side of tube 5 . the lateral tube is attached at one end to the catheter hub and at the other end to a flexible medication tube 6 . the end of the lateral tube that is connected to the catheter hub extends inside this hub to an internal chamber 3i shown in fig4 . the internal chamber 3i communicates with the passageway within the catheter , permitting medications to be admitted to the selected vein by applying them through tube 6 . the lateral tube also permits blood pressure monitoring to aid in determining when a selected artery has been penetrated . fig3 shows a cross sectional view of the support tube 2 , and the support tube hub or simply the support hub 2b , with the finder needle 1 passing through these two components . however , the finder needle is shown in this figure with its tip 1e withdrawn to the point where it lies totally within the passageway of the support tube and it is locked in this position by an automatic latching mechanism within the hub 2b . the purpose of this automatic latching mechanism is to prevent the finder needle tip from being exposed after being used to draw blood from a patient who is infected with a potentially lethal virus . the shielding of the tip of the finder needle in this way prevents sticks from occurring and thereby aids in preventing the transmission of this virus to the physician . this automatic latching mechanism consists of the support hub pin 2e , a spring platform 2f , a support hub spring 2g , a sheath 1g , attached to and closely surrounding the finder needle 1 , and a detent 1f in the sheath 1g . the support hub pin passes through a support hub port 2j in the top of the hub 2b and extends into and through a chamber 2i inside the hub to make contact with a side of the finder needle . the port 2j fits closely about the support hub pin 2e to prevent blood that has entered the chamber 2i from flowing outside the hub through this port . the spring platform is a projection from a side wall of the chamber 2i that is at a point which is typically one half the distance from the finder needle to the top of the chamber 2i . this platform generally extends horizontally across the inside of the chamber 2i and loosely surround the pin 2e so as to not impede the movement of this pin . the spring 2g surrounds the pin 2e in the area between the top of the chamber 2i and the spring platform . the spring is attached at its lower end to the spring platform and at its upper end to the support hub pin 2e . the spring is biased to urge the support hub pin 2e downward against the finder needle . the detent 1f is sufficiently wide to accept the lower end of the support hub pin 2e which locks the finder needle at a position within the support tube as shown in fig3 . this position prevents the tip of the finder needle 1e from being exposed and thereby reduces the risk of sticks with a contaminated needle . the support tube also has a tip 2a which must be sufficiently sharp to penetrate the patient , but this tip is not as sharp as the tip of the finder needle and it is appreciably larger , substantially reducing the risk of a stick as compared to the sticks which could easily occur with the sharp point and small diameter of the finder needle . the sheath 1g about the finder needle need not extend to the tip of the finder needle . it can be cut off at a point such as 1h shown in fig3 leaving the standard , bare finder needle for insertion into the patient . as will be apparent to those skilled in the art , the spring platform is not necessary to have a spring urge the control pin 1 against the finder needle . for example , the spring could be connected directly to the chamber wall rather than the spring platform . however , the spring platform has another purpose and that is to prevent the control pin from being urged too far down in the chamber by the spring . the support hub pin 2e contains a stop 2k which is a projection on the side of the pin that is intercepted by the spring platform . this interception prevents the pin from going past the upper side of the finder needle . the use of the stops prevents the tip of the finder needle from being pushed into the pin and damaging the needle . to pass the finder needle through the support tube hub , it is preferable to raise the support hub pin 2e upward by grasping the pin &# 39 ; s upper end and lifting it upward and out of the way . however , this action is not absolutely necessary in order to insert the finder needle because the pin only can penetrate downward as far at the side of the finder needle . it will ride up on the sheath 1g as the needle is inserted into the support tube . to move the finder needle beyond the detent , the control pin is lifted upward . the upper end of the pin 2e has a horizontal projection 2m which makes lifting the pin with one finger a simple task . the catheter hub 3b contains a second safety device which is shown in fig4 . this device is an automatic blood flow shut off valve , referred to hereinafter as simply the shut off valve . this device automatically prevents the flow of blood form the rear of the catheter hub when the finder needle and support tube are withdrawn . it also prevents air from entering the patients blood stream which could be catastrophic . it thereby leaves the physician free to concentrate on other matters while this device automatically does the important work of preventing the spill of contaminated blood from the catheter hub and preventing air from entering the system . the shut off valve comprises a catheter hub pin 3e , a valve slider 3f , a catheter hub spring 3g , and a valve stop 3n . with one exception , all of these components are contained totally within a chamber 3i located within hub 3b . the exception is pin 3e which is positioned vertically and extends from the outside of the chamber at its top through a catheter hub pin port 3j in the top of the hub to the inside of the chamber at its bottom . the port 3j is sufficiently large to permit the pin 3e to move in a vertical direction , but this port also fits tightly about this pin to prevent blood within the hub from escaping to the outside . this chamber is generally sealed from the outside except for three other ports , 3k , 3l and the port to admit lateral tube 5 , 3t . during the initial phases of this procedure , lateral tube 5 is generally sealed off by valve 3s located inside tube 5 , as shown in fig4 . ports 3k and 3m are the left and right chamber ports respectively designed to admit the support tube and permit it to pass through the chamber into the catheter . the support tube closely fits within these ports and generally seals the chamber until it is withdrawn . the lower end of pin 3e is connected to the valve slider 3f which , in the configuration shown in fig4 is u - shaped in cross section , running parallel to the left chamber wall on the left side and parallel to the right chamber wall on the right side . the bottom element of the &# 34 ; u &# 34 ; runs horizontally and connects the left and right sides of the &# 34 ; u &# 34 ; at their bottom ends . the chamber walls are all generally vertical and provide a uniform cross section in the horizontal plane which is spanned by the valve slider . the catheter hub spring 3g is seated within the valve slider with one end resting on the bottom element of the &# 34 ; u &# 34 ; and the upper end resting against the top of the chamber . the spring 3g is biased to urge the valve slider down and against the support tube 2 . as soon as the support tube is removed , the spring continues to urge the valve slider downward past the ports 3k and 3l until it rests on the valve slider stop 3n , which is a projection from the chamber wall running generally horizontally across the chamber below these ports in the chamber . the left side of the valve slider fits closely against the left wall of the chamber 3i and when the valve slider is in its lower position resting on the slider stop , it seals the left side of the chamber completely , automatically preventing any blood flow out of the chamber . any blood that was located immediately below the valve slider is forced down through an open in the slider stop 3r to the lower portion of the chamber . the right side of the slider contain a port 3t to allow medications entering the chamber through the lateral tube 5 to proceed through this port into the catheter and the selected vein . the upper end of the pin 3e includes a lateral projection 3m at its top which facilitates lifting the pin and the valve slider to permit entry of the support tube on the initial set up of the assembly . once the support tube is in place , the automatic shut off valve operates without any effort on the part of the physician , preventing unwanted , contaminated blood flow automatically upon the removal of the support tube . it will evident to those skilled in the art that although the internal chamber of the catheter hub 3i and its associated components are drawn parallel to a vertical axis passing through the center of this chamber for illustrative purposes . it can be easily seen that virtually any axis generally orthogonal to the central axis of the catheter could be used with generally equivalent results . with further consideration , it can be seen that it is possible to use any axis whether orthogonal or not to the central axis of the catheter for this purpose and although the claims refer to the vertical axis , all axis &# 39 ; s result in equivalent devices which are considered within the scope of the following claims .
a catheter placement system designed to permit a physician to quickly and safely place a large gage catheter into a selected major vein , while avoiding injury to the selected vein , nerves or other veins located about the area of the insertion . initially , a small finder needle is inserted into the area where selected vein is expected to be located to cause as little damage as possible to the surrounding tissue . once blood is drawn easily through the finder needle , the selected vein has been located . the finder needle is placed coaxially within a support tube , which is placed coaxially within the catheter . the finder needle is used as a guide for the support tube and catheter , which are moved together over the finder needle into the selected vein , with the support tube providing needed support for the usually flexible catheter to make it rigid while progressing to the selected vein . once the catheter is placed in the selected major vein , the small needle and support tube can be withdrawn through the distal end of the catheter . during the withdrawal of the finder needle and support tube from the catheter , the finder needle is automatically locked within the support tube to prevent sticks and the rear of the catheter is automatically closed to prevent the flow of contaminated blood from the catheter and also to prevent air from entering the patients blood stream .