as described in further detail below , the present invention takes advantage of the tumescent technique in order to provide intermittent infiltration of local anesthetic . the present invention results in a significant decrease in patient discomfort due to the elimination of the piston - like in and out motion of the cannula . once the cannula is in place , there is no need to push the cannula through the tissue in order to deliver the fluid to a wide area . using the tumescent technique , the time needed in order to complete the infiltration of a targeted anatomic area is reduced to nearly half of the time required when using traditional prior art cannulas . the device and method described herein can use multiple ( e . g ., two ) infiltration cannulas simultaneously . while one cannula is actively dispersing tumescent fluid into the subcutaneous tissue , the surgeon can reposition a second infiltration cannula . this allows the infiltration process to proceed without interruption , whereas prior art techniques of infiltration must be ceased each time the cannula is withdrawn from the skin and re - inserted into another direction . the tumescent technique was discovered by jeffrey alan klein , m . d . ( the applicant ) in 1985 . dr . klein first published a description of the tumescent technique in 1987 when he described the use of dilute lidocaine and epinephrine to permit liposuction totally by local anesthesia . a detailed description of the tumescent technique has not been published in anesthesiology literature , and therefore , the unique benefits of the tumescent technique are not well recognized by anesthesiologists . the tumescent technique is a drug delivery system that takes advantage of a recently discovered reservoir effect of injecting a relatively large volume of relatively dilute solution of a drug into the subcutaneous tissue . the present invention takes advantage of the tumescent reservoir phenomenon . it has many novel applications , an example of which is pain management . this technique eliminates the need for a continuous infiltration of local anesthetic and allows for intermittent injections . in exemplary embodiments , the intermittent injections are administered every eight to twelve hours . with the tumescent technique , a large volume of dilute solution of local anesthesia and epinephrine is injected into the subcutaneous space resulting in a large bolus ( or reservoir ) of solution . the profound vasoconstrictive effect ( shrinking of the capillaries ) of the dilute epinephrine produces a dramatic delay in the systemic absorption of the local anesthetic , which prolongs the anesthetic effects of tumescent anesthesia for eight to sixteen times longer than traditional techniques . referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the present invention only , and not for purposes of limiting the same , fig1 and 2 illustrate a stainless steel ( reusable ) infiltration cannula 10 and fig3 - 4 illustrate a ( single use ) plastic infiltration cannula 30 . the cannula 10 , 30 can be inserted under the skin 52 and into the subcutaneous tissue 50 and tumescent local anesthesia can be infiltrated once every eight to twelve hours . stainless steel infiltration cannulas 10 , such as the one shown in fig1 and 2 , are precision high quality and reusable . these cannulas can be used to provide tumescent local anesthesia for surgical procedures , such as liposuction , which require tumescent local anesthesia over a relatively large area . the cannula 10 includes a tubular needle portion 12 which has a proximal end 14 and a distal end 16 . the proximal end 14 of the tubular needle 12 is attached to a hub 20 that is used by the anesthesiologist or surgeon to hold the cannula 10 during the infiltration procedure . the hub 20 is connected to the tubular needle 12 at a first end 22 and has a connector 24 , such as a luer lock , at an opposing second end . the connector 24 is connected to a fluid source , such as tubing connected to an iv bag . fluid enters the cannula 10 via the connector 24 . in exemplary embodiments , the tip at the distal end 16 is closed . the local anesthetic is infiltrated into the patient via apertures 18 located proximate the distal end 16 of the tubular needle 12 of the cannula 10 . in exemplary embodiments , the apertures 18 are disposed along the distal end 16 of the cannula 10 in a spiral or helical pattern and are distributed over the distal 33 % to 90 % of the tubular needle 12 of the cannula 10 . for example , if the length of the tubular needle d is 15 cm and the apertures 18 at the distal end 16 cover a length d 1 of 5 cm , the pattern of apertures of the cannula 10 are distributed over 33 % of the tubular needle 12 of the cannula 10 . the proximal portion 14 of the cannula 10 is devoid of apertures , in order to prevent fluid from leaking out of the cannula insertion site in the skin . plastic infiltration cannulas 30 , such as the one shown in fig3 and 4 , are single use cannulas and can be used in one of several unique ways . first , an anesthesiologist or surgeon can insert an infiltration cannula 30 with stylet 46 into the subcutaneous tissue 50 , remove the stylet 46 , then attach an iv tubing to the infiltrator and inject tumescent local anesthesia into the targeted area without subsequent repositioning of the infiltration cannula 30 . the plastic flexible nature of the tubular needle 32 of the disposable plastic cannula 30 allows the patient to move or change position of the body without risk of injury that might result if a patient moves while a rigid steel cannula is inserted . preferably , the stylet 46 is metal , e . g ., stainless steel . the plastic cannula 30 can be blunt - tipped with the metal stylet tip 48 covered by the rounded tip 39 of the plastic cannula 30 . alternatively , the plastic cannula 30 can be open - ended with the stylet 46 extending a short distance past the end 39 of the plastic cannula . 30 . in the case of an open - ended cannula , the metal stylet 46 can be either blunt - tipped ( requiring a skin incision to permit insertion into the subcutaneous space ), or sharp - tipped ( permitting the cannula to be inserted directly through the skin and into the subcutaneous space without requiring a preparatory skin incision . the plastic cannula shown in fig3 and 4 is similar to an iv catheter except the sharp hollow stylet used for the insertion of an iv catheter is replaced by a solid obturator / stylet 46 that can be either sharp or blunt tipped . except for the removable stylet 46 , the plastic cannula 30 is similar to the stainless steel cannula 10 shown in fig1 and 2 and described above . the plastic cannula 30 includes a flexible tubular needle 32 having a proximal end 34 and a distal end 36 . the distal end has apertures 38 and the proximal end 34 is devoid of apertures . as stated above , in exemplary embodiments , the pattern of apertures 38 in the cannula 30 are distributed over the distal 33 % to 90 % of the tubular needle 32 of the cannula 30 . for example , if the tubular needle 32 of cannula 30 shown in fig3 and 4 has a length d of 15 cm and the pattern of apertures are distributed over a length d 1 of 13 . 5 cm , then the apertures 38 are distributed over 90 % of the cannula . a typical infiltration cannula 10 , 30 might be 20 , 18 , 16 or 14 gauge ( i . e ., 20 , 18 , 16 or 14 cm in length ) with small apertures 18 , 38 placed every 5 mm d 2 along the cannula in a spiral or helical pattern . it will be appreciated that the dimensions used herein are exemplary and that the cannula dimensions , range of gauge , relative size shape and pattern of apertures can vary greatly depending upon clinical preference . the proximal end 34 of the tubular needle 32 shown in fig3 and 4 is attached to a hub 40 that is used by the anesthesiologist or surgeon to hold the cannula 30 during the infiltration procedure . the hub 40 is connected to the tubular needle 32 at a first end 42 and has a connector 44 at an opposing second end . the connector 44 is connected to a fluid source . as described above and shown in fig4 , the stylet 46 can be inserted and removed from the cannula 30 . infiltration using a plastic infiltration cannula 30 , such as the one shown in fig3 and 4 , can be accomplished using an infiltration pump . alternatively , the force of gravity could be used to push the tumescent fluid into the tissues by hanging a reservoir plastic bag of tumescent local anesthesia ( or other dilute drug , such as a chemotherapeutic agent or antibiotics ) on an iv pole and connecting bag to the infiltration cannula by an iv line . another application is the injection of tumescent local anesthesia into a localized area through which a surgeon plans to make a surgical incision . the effects of vasoconstriction within the tumesced tissue minimizes surgical bleeding . the effects of tumescent local anesthesia produce prolonged post operative analgesia and also reduce the risk of surgical wound infections . yet another application is to provide an easily accessible route for systemic administration of crystalloid fluids / electrolytes for systemic hydration or for other types of drug therapy . potential clinical applications include emergency resuscitation with systemic fluids in situations where insertion of an iv catheter into a vein cannot be readily achieved . examples of situations where emergency access for intravenous delivery of fluids might not be possible include acute trauma or burn wound in civilian or military situations . another application might be the emergency treatment of dehydration associated with prolonged vomiting or diarrhea ( e . g ., epidemic cholera ) such as among pediatric patients in rural ( e . g ., third world ) settings . a subcutaneous infiltration catheter can easily be placed by a layman , whereas inserting an iv catheter into a patient that is severely dehydrated can be difficult even for a skilled physician . delivery of systemic fluids by subcutaneous infiltration is safer in a zero gravity situation ( for example , the space station ). the addition of a small amount of capillary vasodilator ( e . g ., methylnicotinamide ) to the subcutaneous fluid can be used to accelerate the systemic absorption of the fluid or drug into the intravascular space . the cannula 10 , 30 is intended to be inserted far enough through the skin 52 so that all of the apertures 18 , 38 are within the fat 50 of the patient . once the cannula 10 , 30 is properly positioned , it can remain stationary while the local anesthetic ( or other pharmaceutical ) solution is injected . after one portion of the targeted area has been tumesced , the infiltration is briefly terminated ( either by turning off the pump or by clamping the iv tubing ) while the cannula 10 , 30 is repositioned into another area of the subcutaneous tissue . the infiltration is then restarted with the cannula stationary in its new position . the infiltrator 10 , 30 can also be used in the traditional mode whereby the cannula 10 , 30 is moved through the targeted tissue while the fluid is simultaneously pumped through the cannula 10 , 30 and into the subcutaneous tissue 50 . another unique aspect of the tumescent technique &# 39 ; s reservoir effect is that one can conveniently achieve a long slow steady absorption of a drug delivered to the subcutaneous space 50 using periodic injections of a tumescent solution . in certain situations , using a slow iv infusion , the alternative technique , can achieve a slow systemic absorption of a drug but may be difficult , require greater clinical expertise , be more expensive , and therefore , less practical than the technique described herein . fig5 is a flow diagram illustrating steps performed in an exemplary infiltration procedure using a cannula 10 , 30 such as the one shown in fig1 and 2 or the one shown in fig3 and 4 , respectively . the procedure begins by inserting the tubular needle 12 , 32 of the infiltration cannula 10 , 30 into a desired subcutaneous tissue site 50 , e . g ., via an incision in the patient &# 39 ; s skin 52 ( block 100 ). fluid is then transported from the fluid source ( e . g ., an iv bag ) into the cannula 10 , 30 via the connector 24 , 44 that is connected to the fluid source . the fluid is transported from the connector 24 , 44 through the hub 20 , 40 and into the tubular needle 12 , 32 ( block 102 ). the fluid is then ejected from the cannula 10 , 30 into the subcutaneous tissue 50 of the patient via the apertures 18 , 38 at the distal end 16 , 36 of the tubular needle 12 , 34 of the cannula 10 . 30 ( block 104 ). the fluid is transported ( block 102 ) and ejected ( block 104 ) until infiltration at the current site is completed ( yes in decision block 106 ). the fluid can be injected into multiple sites in order to distribute the solution over a greater area . infiltration at a particular site may be deemed complete upon emptying of the fluid source or based on the anesthesiologist or surgeon &# 39 ; s decision to stop the infiltration at the current site . after one portion of the targeted area has been tumesced , the infiltration can be briefly terminated ( either by turning off the pump or by clamping the iv tubing ) while the cannula 10 , 30 is repositioned into another area of the subcutaneous tissue . the infiltration is then restarted with the cannula stationary in its new position . if the infiltration at a site is complete ( yes in decision block 106 ), the cannula is removed from the current site ( block 108 ). if the infiltration at the current site is not complete ( no in decision block 106 ), fluid is transported from the fluid source ( block 102 ) and ejected into the subcutaneous tissue ( block 104 ) until infiltration at the site is complete ( yes in decision block 106 ). if infiltration is complete at the current site ( yes in decision block 106 ) but infiltration is not complete ( no in decision block 110 ), the tubular needle 12 , 32 of the infiltration cannula 10 , 30 is inserted into a new area of subcutaneous tissue 50 . the process described above is performed until the infiltration process is complete ( yes in decision block 110 ). this process can be repeated intermittently , for example every eight to twelve hours as described above . as described above , multiple infiltration cannulas ( e . g ., can be used at once ). thus , a second cannula can be inserted ( block 100 ) at the same time as a first cannula is being removed ( block 108 ). thus , the infiltration process need not be interrupted in order to reposition a single cannula . additional modifications and improvements of the present invention may also be apparent to those of ordinary skill in the art . thus , the particular combination of parts described and illustrated herein is intended to represent only a certain embodiment of the present invention , and is not intended to serve as a limitation of alternative devices within the spirit and scope of the invention .
an infiltration cannula and method of using the infiltration cannula during an infiltration procedure are disclosed herein . the infiltration cannula includes : a tubular needle and a hub . the tubular needle has a proximal end and a distal end . the tubular needle also has a plurality of apertures disposed in a pattern about the distal end . the apertures are configured to infiltrate fluid into the subcutaneous tissue of a patient . the hub is configured to be held by a person performing the infiltration procedure . the hub has a first end and an opposing second end . the first end is attached to the proximal end of the tubular needle and the second end includes a connector configured to connect to an input source for receiving the fluid to be infiltrated into the subcutaneous tissue of the patient . the fluid flows from the connector , through the hub and into the tubular needle .