fig1 - 3 illustrate a first embodiment of a device constructed in accordance with the present invention . a tube inserter 100 includes a cannula 110 having a threaded cutting portion 112 at its distal end and a conduit 114 ( shown in dashed line in fig1 ) running from its distal end along a portion of the length of the cannula 110 . holes 116 formed in the tip of cannula 110 and holes 118 formed in the side of cannula 110 create a fluid passageway from the holes 116 to the holes 118 along conduit 114 . a catheter 120 comprises an outer tube having an outer threaded portion 122 at the distal end and a lumen 124 running along its entire length , with the ends of the lumen 124 defining a distal opening 126 and a proximal opening 128 . in a preferred embodiment the catheter 120 includes graduated markings ( not shown ) on the outer surface to indicate distances , for example , the distance from each graduation to the cutting tip 112 . in addition , if desired , the graduated markings can be angled so that they provide the user of the device with an indication of the preferred insertion angle . at the proximal end of catheter 120 is a head assembly 130 , which includes a check valve 134 , a port 136 and an o - ring 138 . in the embodiment illustrated in fig1 - 3 , a threaded outer portion 132 is shown , to provide a compression fit between a chest tube inserted in the catheter and the head assembly , as discussed in more detail below . a control device , such as a leur cap , is affixed or otherwise associated with port 136 to enable control of the flow of fluid or other materials therethrough . the location of port 136 along the catheter 120 should coincide with the holes 118 when the cannula 110 is inserted into the catheter 120 as shown in fig3 . the o - ring ( or other sealing means ) is positioned within the lumen 124 such that , when the cannula 110 is inserted into the catheter 120 as shown in fig3 it allows fluid to travel from the distal end of the tube inserter 100 , through holes 116 , through conduit 114 , and out through holes 118 to port 136 , while preventing the flow of fluid towards the portion of the proximal end of the tube inserter 100 past port 136 . an adjustable flange 140 is positionable along the threaded portion 122 of catheter 120 . its position can be adjusted to be closer to or farther from the distal end of the tube inserter 100 . in a preferred embodiment the adjustable flange comprises a disk having a centrally - located opening formed therein , with the opening having internal threading to match the external threading of threaded portion 122 . so configured , the adjustable flange can be moved up or down the catheter 120 by rotation of the adjustable flange thereon . although not shown , if desired the adjustable flange 140 can be angled to the preferred insertion angle to act as a guide for the user . check valve 134 allows the cannula 110 to be inserted into the lumen 124 when desired ( shown inserted in fig3 ). when cannula 110 is removed from lumen 124 ( shown in fig2 ), the check valve 134 prevents the inflow or out flow of fluids ( or any material or composition ) through the proximal opening 128 . referring to fig4 - 7 , the method of using the present invention for insertion of a chest tube is now described . referring to fig4 the tube inserter 100 , fully assembled as shown in fig3 is placed tip first against the insertion location 400 on the skin 402 of a patient so that the threaded cutting portion 112 is in contact with the entrance location . the entire tube inserter 100 is then turned and advanced into the pleural space 404 . the screw design allows for a controlled insertion into the chest , with minimal pushing force , since progression relies on rotation of the pitched screw threads . the threaded cutting portion 112 eliminates the need for an initial incision , and the air / fluid passageway in the cannula 110 provides a method for the user of the device to determine whether the tip of the device is in the pleural space 404 and the nature of the injury ( e . g ., the presence of blood at port 136 indicates the presence of hemothorax ). as shown in fig5 the adjustable flange 140 limits the depth of the penetration by stopping the insertion at the skin 402 , and therefore minimizes the risk of injury to internal organs , such as to lung 504 . further , the ability to easily adjust the depth of penetration using adjustable flange 140 allows a non - physician to simply set the depth and be assured that a maximum depth is not exceeded . fig5 illustrates the tube inserter 100 fully inserted into the patient , such that the threaded cutting portion 112 has pierced the parietal pleura and entered the pleural space 404 . note that the cutting portion 112 has stopped short of contacting the visceral pleura 502 and the lung 504 . when insertion is complete and it has been determined that the device tip is in the pleural space 404 , as shown in fig6 the cannula 110 along with its threaded cutting portion 112 is removed , leaving the catheter 120 in place , with the check valve and leur cap closed . a chest tube 700 , which is connected to a heimlich valve or other type of one - way valve , can now be advanced into the pleural space 404 as shown in fig7 . preferably the chest tube 700 is locked or otherwise secured in place in the catheter 120 during use , to prevent it from accidentally being advanced into or retracted from the pleural cavity . for example , the chest tube 700 can be supplied with a mating device 702 having an internal threading which matches the outer threading 132 of catheter 120 ; the exact method and structure for maintaining the chest tube in place is not the focus of this invention and therefore any method and structure for maintaining a tight or “ compression fit ” is contemplated by the previous description . the excavation of pneumothorax and / or hemothorax is carried out in the usual manner using the chest tube and the appropriate removal methods and apparatus . the device can be inserted to the chest wall at various angles with minimal normal (“ push ”) and rotational forces , and with a high degree of control of insertion depth . while in this operative position , the chest tube and catheter 120 remain positionally stable within the chest wall . due to the threading along the outer surface of the catheter 120 , a high degree of force is required to pull the assembly out accidentally . further , once the pneumothorax or hemothorax has been resolved , the apparatus is easily removed from the chest by rotating the apparatus out along the threads . fig8 illustrates an alternative embodiment for the cannula of the present invention . as shown in fig8 a cannula 810 has a spline 811 running from the cutting tip 812 up to a location 818 . location 818 is selected so that it will be adjacent to port 136 ( fig2 ) when the cannula is inserted into catheter 120 . the spline provides a fluid passage ( i . e ., a conduit ) along the outer edge of the cannula ( between the cannula 110 and the inner wall of catheter 120 ) so that fluid may pass from the tip of the cannula to the port 136 , as described above with respect to fig1 - 3 . while there are many materials that can be used to fabricate the device of the present invention , in a preferred embodiment the cutting tip 112 is made of stainless steel or titanium in a generally conical shape , with threads , and converging at a sharpened tip at the distal end thereof . the remainder of the device , in a preferred embodiment , is made of injection molded clear plastic so that fluid traveling through the device may be viewed by the user . obviously other materials can be used without detracting from the novel aspects of the invention disclosed herein . the present invention enables prompt and inexpensive management of pneumo / hemothorax in humans and has broad - range application in areas such as combat casualty care , fire and rescue , and shock trauma centers . further , while the present invention is disclosed and described in a preferred embodiment pertaining to chest tubes , it is understood and contemplated that it can be applied to insertion devices of other types , such as abdominal drains and drains inserted into joints or other body cavities ; introduction of a port of entry into the body ( e . g ., pleural and peritoneal spaces , joints ) for diagnostic and therapeutic purposes ; introduction of a laproscope , and firm and stable fixation of other medical instrumentation to soft tissues ( e . g ., chest and abdominal wall ) using the screw concept disclosed herein . the foregoing is considered as illustrative only of the principles of the invention . further , since numerous modifications and changes will readily occur to those skilled in the art , it is not desired to limit the invention to the exact construction and applications shown and described . accordingly , all suitable modifications and equivalents may be resorted to , falling within the scope of the invention and the appended claims and their equivalents .
the present invention is a device and method for gaining access , quickly and inexpensively , to a body cavity for the purpose of inserting into the cavity a medical device , such as a chest tube . the device generally comprises a catheter and a cannula insertable into the catheter during an insertion procedure . the cannula has a cutting tip that extends beyond one end of the catheter . the cutting tip enables simple insertion of the device into the body without requiring substantial pushing force . once the device is inserted in the body , the cannula is removed , leaving a path of entry into the body cavity , while removing the sharp cutting tip from the area to reduce the likelihood of injury to a patient in whom the device is inserted .