Abstract:
An apparatus for accessing bone marrow inside a bone is provided. The apparatus may include a penetrator assembly having a tissue penetrator and a hub. The tissue penetrator my have a hollow cannula disposed in fixed relation to the hub. The apparatus may also have a driver configured to insert a portion of the tissue penetrator into the bone and bone marrow, and a depth control mechanism configured to control the depth of penetration of the tissue penetrator into the bone and bone marrow. The depth control mechanism may have a sensor configured to detect a position of the bone and bone marrow. The depth control mechanism may also have a mechanical stop.

Description:
RELATED APPLICATION 
       [0001]    This application is a continuation application of U.S. patent application Ser. No. 11/023,173, filed Dec. 27, 2004, which is a continuation of U.S. patent application Ser. No. 10/987,051, filed Nov. 12, 2004, which claims priority to U.S. Provisional Patent Application No. 60/519,462, filed Nov. 12, 2003, which also claims foreign priority to Taiwan Patent Application No. 93134480, filed Nov. 11, 2004, and which is also a continuation-in-part application of U.S. patent application Ser. No. 10/449,503, filed May 30, 2003, which claims priority to U.S. Provisional Patent Application No. 60/384,756, filed May 31, 2002, the contents of which are hereby incorporated in their entirety by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention is related in general to an apparatus and method to access the bone marrow and specifically to an apparatus and method for accessing the bone marrow of a human&#39;s sternum. 
       BACKGROUND OF THE INVENTION 
       [0003]    Every year, millions of patients are treated for life-threatening emergencies in the United States. Such emergencies include shock, trauma, cardiac arrest, drug overdoses, diabetic ketoacidosis, arrhythmias, burns, and status epilepticus just to name a few. For example, according to the American Heart Association, more than 1,500,000 patients suffer from heart attacks (myocardial infarctions) every year, with over 500,000 of them dying from its devastating complications. In addition, many wounded soldiers die unnecessarily because intravenous (IV) access cannot be achieved in a timely manner. Many soldiers die within an hour of injury, usually from severe bleeding and/or shock. 
         [0004]    An essential element for treating all such emergencies is the rapid establishment of an IV line in order to administer drugs and fluids directly into the circulatory system. Whether in the ambulance by paramedics, in the emergency room by emergency specialists or on the battlefield by an Army medic, the goal is the same—to start an IV in order to administer life-saving drugs and fluids. To a large degree, the ability to successfully treat such critical emergencies is dependent on the skill and luck of the operator in accomplishing vascular access. While it is relatively easy to start an IV on some patients, doctors, nurses and paramedics often experience great difficulty establishing IV access in approximately 20 percent of patients. The success rate on the battlefield is much lower where Army medics are only about 29 percent successful in starting an IV line during emergency conditions in the field. These patients are probed repeatedly with sharp needles in an attempt to solve this problem and may require an invasive procedure to finally establish an intravenous route. 
         [0005]    In the case of patients with chronic disease or the elderly, the availability of easily-accessible veins may be depleted. Other patients may have no available IV sites due to anatomical scarcity of peripheral veins, obesity, extreme dehydration or previous IV drug use. For these patients, finding a suitable site for administering lifesaving drugs becomes a monumental and frustrating task. While morbidity and mortality statistics are not generally available, it is known that many patients with life-threatening emergencies have died of ensuing complications because access to the vascular system with life-saving IV therapy was delayed or simply not possible. For such patients, an alternative approach is required. 
         [0006]    The intraosseous (IO) space provides a direct conduit to the systemic circulation and, therefore, is an attractive alternate route to administer IV drugs and fluids. Intraosseous infusion has long been the standard of care in pediatric emergencies when rapid IV access is not possible. The military used hand-driven IO needles for infusions extensively and successfully during World War II, but the needles were cumbersome, difficult to use, and often had to be driven into the bone. Drugs administered intraosseously enter the circulation as rapidly as they do when given intravenously. In essence, the bone marrow is considered to be a large non-collapsible vein. 
         [0007]    Although effective in achieving IO access, the currently available IO infusion devices suffer from several significant limitations. Current devices are single-use only and bulky, which limits the number of devices a medic can take into the field. Manually inserted IO needles are very difficult to use in hard adult bones. Current devices frequently penetrate not only the anterior bone cortex, but may also the posterior cortex. In addition, some current devices pose a significant risk of shattering the bone upon use. After the needle is inserted, many current devices suffer from a high rate of dislodgement from the bone because of the non-axial manner in which they must be inserted. Dislodgement often leads to extravasation (leakage of fluid from the entry points of the needle). 
       SUMMARY OF THE INVENTION 
       [0008]    In accordance with teachings of the present invention, various embodiments of an apparatus to access the bone marrow of a human&#39;s sternum are provided including various embodiments of a means to control depth of penetration into the bone marrow. In some embodiments, an apparatus of the invention includes a tissue penetrator configured to penetrate the sternum, a power mechanism operable to drive the tissue penetrator into the sternum (driver), and a depth control mechanism operable to control the depth of penetration of the tissue penetrator into the sternum. The tissue penetrator may include a pressure-sensitive probe capable of transmitting pressure changes to a sensor within the apparatus. The power mechanism may include axial force delivered by an operator. A driver may include a power source selected from the group consisting of a motor, a battery, a coded spring, compressed gas, and a solar power cell. A tissue penetrator may include an outer cannula and an inner trocar. A tissue penetrator assembly may include a tissue penetrator, a connector such as a luer lock, a collar, and/or a blade. A depth control mechanism may include a trigger, physical stops at preset positions, a revolutions-per-minute (RPM) sensor, a torque sensor, a power sensor, a reverse clutch, a gear, an ultrasound sensor, and/or a depth probe or sensor. A trigger may be operably connected to the motor and/or a switch such that upon meeting a preset condition (e.g. change in RPM or torque, change in power consumption, physical con tact with bone), tissue penetrator advancement is either terminated or proceeds to a. preset depth level. 
         [0009]    According to some embodiments of the invention, the driving force for tissue penetration is derived in whole or in part from the application of pressure by the operator. The applied pressure may activate a driver according to the invention. When the applied pressure surpasses a. preset threshold, it may engage a. manual driver means whereby operator action (e.g. pressure or movement) directly advances the tissue penetrator. 
         [0010]    The present invention also provides a tissue penetrator that includes a means, whereby the tissue penetrator itself serves as the depth probe. Thus, the tissue penetrator itself may include a sensor operably linked to a trigger that, in turn, is operably linked to the driver. 
         [0011]    In addition, the present invention provides a method of rapidly establishing access to intraosseous circulation via the intraosseous space including contacting a subject with an apparatus having a tissue penetrator configured to penetrate the sternum, a driver operable to drive the tissue penetrator into the sternum, and a. depth control mechanism operable to control the depth of penetration of the tissue penetrator into the sternum and deploying the tissue penetrator. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    A more complete and thorough understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein: 
           [0013]      FIG. 1  is a schematic drawing showing the gross bone stmcture of the sternocostal region of a human; 
           [0014]      FIG. 2A  is a schematic drawing showing a longitudinal cross-section of an apparatus for accessing sternal bone marrow and a human sternum, wherein the apparatus is positioned on the skin of a human at the location shown in  FIG. 1  and the tissue penetrator has penetrated the skin and muscle; 
           [0015]      FIG. 2B  is a schematic drawing of the apparatus and sternum shown in  FIG. 2A , wherein the tissue penetrator has penetrated the skin, muscle, and anterior cortex and entered the intraosseous space; 
           [0016]      FIG. 3A  is a schematic drawing showing a longitudinal cross-section of an apparatus for accessing sternal bone marrow and a human sternum, wherein the apparatus is positioned on the skin of a human at the location shown in  FIG. 1  and the tissue penetrator has penetrated the skin and muscle; 
           [0017]      FIG. 3B  is a schematic drawing of the apparatus and sternum shown in  FIG. 3A , wherein the tissue penetrator has penetrated the skin, muscle, and anterior cortex and entered the intraosseous space; 
           [0018]      FIG. 4A  is a schematic drawing showing a longitudinal cross-section of an apparatus for accessing sternal bone marrow and a human sternum, wherein the apparatus is positioned on the skin of a human at the location shown in  FIG. 1 ; 
           [0019]      FIG. 4B  is a schematic drawing of the apparatus and sternum shown in  FIG. 4A , wherein the tissue penetrator has penetrated the skin and muscle; 
           [0020]      FIG. 4C  is a schematic drawing of the apparatus and sternum shown in  FIG. 4A , wherein the tissue penetrator has penetrated the skin, muscle, and anterior cortex and entered the intraosseous space; 
           [0021]      FIG. 5  is a schematic drawing showing an elevation view of a tissue penetrator having a depth control mechanism actuated by a gear in accordance with the teachings of the present invention; 
           [0022]      FIG. 6A  is a schematic drawing showing a longitudinal cross-section of an apparatus for accessing, sternal bone marrow and a human sternum, wherein the apparatus is positioned on the skin of a human at the location shown in  FIG. 1 ; 
           [0023]      FIG. 6B  is a schematic drawing of the apparatus and sternum shown in  FIG. 6A , wherein the tissue penetrator has penetrated the skin and muscle; 
           [0024]      FIG. 6C  is a schematic drawing of the apparatus and sternum shown in  FIG. 6A , wherein the tissue penetrator has penetrated the skin, muscle, and anterior cortex and entered the intraosseous space; 
           [0025]      FIG. 6D  is a flowchart of the signal processing between the ultrasound sensing device and driver of  FIGS. 6A-6C ; 
           [0026]      FIG. 7  is a schematic drawing showing a longitudinal cross-section of an apparatus for accessing sternal bone marrow and a human sternum, wherein the apparatus is positioned on the skin of a human at the location shown in  FIG. 1 , the probe has penetrated the skin and muscle, and the tissue penetrator has penetrated the skin, muscle, and anterior cortex and entered the intraosseous space; 
           [0027]      FIG. 8  is a schematic drawing showing a longitudinal cross-section of an apparatus for accessing sternal bone marrow and a human sternum, wherein the apparatus is positioned on the skin of a human at the location shown in  FIG. 1 , the sliding, collar has penetrated the skin and muscle, and the tissue penetrator has penetrated the skin, muscle, and anterior cortex and entered the intraosseous space; 
           [0028]      FIG. 9A  is a schematic drawing showing a longitudinal cross-section of an apparatus for accessing sternal hone marrow having a vertical reverse clutch mechanism and a human sternum, wherein the apparatus is positioned on the skin of a human at the location show n in 
           [0029]      FIG. 9B  is a schematic drawing showing a. longitudinal cross-sectional view of the vertical reverse clutch mechanism of the apparatus shown in  FIG. 9A  with the vertical pin in the engaged position; 
           [0030]      FIG. 9C  is a schematic drawing showing a longitudinal cross-sectional view of the reverse clutch mechanism of the apparatus shown in  FIG. 9A  with the vertical pin in the disengaged position; 
           [0031]      FIG. 10A  is a schematic drawing of a plan view of a horizontal reverse clutch mechanism according to the teachings of the present invention wherein the horizontal pins are in the engaged position, contacting the pawls; 
           [0032]      FIG. 10B  is a schematic drawing of the horizontal reverse clutch mechanism shown in  FIG. 10A , wherein the horizontal pins are in the disengaged position, not contacting the pawls, such that the concentric clutch flywheel comes to a rest; 
           [0033]      FIG. 11  is a schematic drawing of horizontal pins with leaf springs, pawls, and the shaft of a horizontal reverse clutch according to the teachings of the present invention; 
           [0034]      FIG. 12A  is a schematic drawing of an apparatus for accessing sternal bone marrow having a torque or RPM sensor; 
           [0035]      FIG. 12B  is a schematic drawing of an apparatus for accessing sternal bone marrow having a power sensor; 
           [0036]      FIG. 13A  is a graph showing the change in torque or amperage as a function of depth of bone penetration with the inflection point marked with an encircled “P” indicating the point at which penetration of the anterior cortex is complete; 
           [0037]      FIG. 13B  is a graph showing the change in power as a function of depth of bone penetration with the inflection point marked with an encircled “P” indicating the point at which penetration of the anterior cortex is complete; 
           [0038]      FIG. 14A  is a schematic drawing showing an elevation view of intraosseous tissue penetrators with collars according to the teachings of the present invention; 
           [0039]      FIG. 14B  is a schematic drawing showing a longitudinal cross-section of an apparatus for accessing sternal bone marrow a human sternum, wherein the apparatus is positioned on the skin of a human at the location shown in  FIG. 1  and the tissue penetrator has penetrated the skin, muscle, and anterior cortex and entered the intraosseous space; 
           [0040]      FIG. 15A  is a schematic drawing showing a longitudinal cross-section of an intraosseous tissue penetrator assembly with a built-in blade according to the teachings of the present invention and a human sternum, wherein the assembly is positioned on the skin of a human at the location shown in  FIG. 1  and the tissue penetrator has not penetrated the skin; 
           [0041]      FIG. 15B  is a schematic drawing showing a radial cross-section of the tissue penetrator assembly shown in  FIG. 15A ; 
           [0042]      FIG. 15C  is a schematic drawing showing a longitudinal cross-section of the tissue penetrator assembly shown in  FIG. 15A  and a human sternum, wherein the tissue penetrator has penetrated the skin and muscle and the blade has penetrated the skin; 
           [0043]      FIG. 15D  is a schematic drawing showing a longitudinal cross-section of the tissue penetrator assembly shown in  FIG. 1 , and a human sternum, wherein the tissue penetrator has penetrated the skin, muscle, and anterior cortex and entered the intraosseous space and wherein the blade is in its retracted position; 
           [0044]      FIG. 16A  is a schematic drawing showing a longitudinal cross-section of an apparatus for accessing sternal bone marrow according to the teachings of the present invention, wherein the reusable handle and the disposable cartridge are in the disengaged position and the needle shield is attached; 
           [0045]      FIG. 16B  is a schematic drawing showing a longitudinal cross-section of the apparatus shown in  FIG. 16A , wherein the reusable handle and the disposable cartridge are in the engaged position and the needle shield is attached; 
           [0046]      FIG. 16C  is a schematic drawing showing a longitudinal cross-section of the apparatus shown in  FIG. 16A , wherein the reusable handle and the disposable cartridge are in the engaged position, the needle shield is detached, and the needle and probes have been inserted into the soft tissue of a subject; 
           [0047]      FIG. 16D  is a schematic drawing showing a longitudinal cross-section of the apparatus shown in  FIG. 16A  and a human sternum, wherein the reusable handle and the disposable cartridge are in the deployed position, the probes have penetrated the skin and muscle, and the tissue penetrator has penetrated the skin, muscle, and anterior cortex and entered the intraosseous space; 
           [0048]      FIG. 16E  is a schematic drawing showing a longitudinal cross-section of the disposable cartridge shown in  FIG. 16D  after the handle has been removed; 
           [0049]      FIG. 17A  is a schematic drawing showing a longitudinal cross-section of an apparatus for accessing sternal bone marrow according to the teachings of the present invention and a human sternum, wherein the reusable handle and the disposable cartridge are in the engaged position, the tissue penetrator has penetrated the skin and muscle; 
           [0050]      FIG. 17B  is a schematic drawing showing a longitudinal cross-section of the apparatus shown in  FIG. 17A , wherein the reusable handle and the disposable cartridge are in the deployed position and the tissue penetrator has penetrated the skin, muscle, and anterior cortex; and 
           [0051]      FIG. 17C  is a schematic drawing showing a longitudinal cross-section of the disposable cartridge shown in  FIG. 17B  after the handle has been removed. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0052]    Some preferred embodiments of the invention and its advantages are best understood by reference to  FIGS. 1-17B  wherein like numbers refer to same and like parts. Table 1 lists reference numerals with their associated names and figures in which they appear. 
         [0000]    
       
         
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 No. 
                 Feature Name 
                 Figures 
               
               
                   
               
             
             
               
                 10 
                 housing 
                 2A, 2B, 3A, 3B, 4A, 4B, 4C, 6A, 6B, 6C, 
               
               
                   
                   
                 7, 8, 9A, 16A, 16B, 16C, 16D, 17A, 17B 
               
               
                 11 
                 cassette housing 
                 16A, 16B, 16C, 16D, 16E 
               
               
                 12 
                 flange 
                 2A, 2B, 3A, 3B, 4A, 6A, 6B, 6C, 7, 8, 9A, 
               
               
                   
                   
                 16A, 16B, 16C, 16D, 17A 
               
               
                 13 
                 support member 
                 16A, 16B, 16C, 16D, 16E 
               
               
                 14 
                 end member 
                 16A, 16B, 16C, 16D, 16E 
               
               
                 15 
                 cartridge 
                 16A, 16E 
               
               
                 16 
                 detent 
                 16A, 16E 
               
               
                 17 
                 engaging lock 
                 16A 
               
               
                 18 
                 needle shield 
                 16A, 16B 
               
               
                 19 
                 reusable handle 
                 16A, 16B, 16C, 16D 
               
               
                 20 
                 driver 
                 2A, 2B, 3A, 3B, 4A, 4B, 4C, 6A, 6B, 7, 8 
               
               
                 21 
                 battery 
                 2A, 2B, 5, 6A, 6B, 6C, 7, 8, 9A 
               
               
                 22 
                 motor 
                 2A, 2B, 5, 6A, 6B, 6C, 7, 8, 9A 
               
               
                 23 
                 drive shaft 
                 2A, 2B, 4A, 4B, 4C, 5, 6A, 6B, 6C, 7, 8, 
               
               
                   
                   
                 9A, 9B, 9C 
               
               
                 24 
                 coupling end 
                 2A, 2B, 6A, 6B, 6C, 7, 8 
               
               
                 25 
                 spring 
                 3A, 3B, 16A, 16B, 16C, 16D, 17A, 17B 
               
               
                 26 
                 coupling end 
                 3A, 3B 
               
               
                 30 
                 tissue penetrator 
                 14B, 17B 
               
               
                   
                 assembly 
               
               
                 31 
                 hub 
                 14B, 17A, 17B, 17C 
               
               
                 32 
                 flange 
                 14B, 17A, 17B, 17C 
               
               
                 33 
                 screw 
                 14B, 17A, 17B, 17C 
               
               
                 34 
                 blade 
                 15A, 15B, 15C, 15D 
               
               
                 35 
                 retraction lever 
                 15A, 15C, 15D 
               
               
                 40 
                 tissue penetrator 
                 2A, 2B, 3A, 3B, 4A, 4B, 4C, 5, 6A, 6B, 
               
               
                   
                   
                 6C, 7, 8, 9A, 9B, 9C, 15A, 15C, 15D, 
               
               
                   
                   
                 16A, 16B, 16C, 16D, 16E, 17A, 17B, 17C 
               
               
                 41 
                 cannula 
                 14A, 14B, 15B 
               
               
                 42 
                 trocar 
                 10A, 10B, 14A, 14B, 15B 
               
               
                 43 
                 collar 
                 14A, 15A, 15C, 15D 
               
               
                 44 
                 sliding collar 
                 8 
               
               
                 45 
                 connector 
                 4A, 4B, 4C, 5, 14B, 16A, 16E, 17A, 17B, 
               
               
                   
                   
                 17C 
               
               
                 46 
                 central line 
                 10A, 10B, 11, 15B 
               
               
                 50 
                 annular stop 
                 2A, 2B, 3A, 3B, 4A, 4B, 4C 
               
               
                 51 
                 first penetrator 
                 4A, 4B, 4C 
               
               
                   
                 shoulder 
               
               
                 52 
                 threaded annulus 
                 4A, 4B, 4C 
               
               
                 53 
                 second penetrator 
                 4A, 4B, 4C 
               
               
                   
                 shoulder 
               
               
                 54 
                 third penetrator 
                 4A, 4B, 4C 
               
               
                   
                 shoulder 
               
               
                 55 
                 ribs 
                 5 
               
               
                 56 
                 gear 
                 5 
               
               
                 57 
                 suspension member 
                 5 
               
               
                 58 
                 support annulus 
                 5 
               
               
                 60 
                 vertical clutch 
                 9A, 9B, 9C 
               
               
                   
                 drive member 
               
               
                 61 
                 vertical clutch 
                 9A, 9B, 9C 
               
               
                   
                 flywheel 
               
               
                 62 
                 vertical engaging 
                 9A, 9B, 9C 
               
               
                   
                 pin 
               
               
                 63 
                 concentric clutch 
                 10A, 10B 
               
               
                   
                 drive member 
               
               
                 64 
                 concentric clutch 
                 10A, 10B, 11 
               
               
                   
                 flywheel 
               
               
                 65 
                 horizontal engaging 
                 10A, 10B, 11 
               
               
                   
                 pin 
               
               
                 66 
                 pawl 
                 10A, 10B, 11 
               
               
                 67 
                 coil sprina 
                 10A, 10B, 11 
               
               
                 68 
                 leaf spring 
                 11 
               
               
                 70 
                 probe 
                 7, 16A, 16B, 16C, 16D, 16E 
               
               
                 71 
                 ultrasonic sensor 
                 6A, 6B, 6C 
               
               
                 90 
                 sternum 
                 1 
               
               
                 91 
                 ribs 
                 1 
               
               
                 92 
                 skin 
                 2A, 2E, 3A, 3B, 4A, 4B, 4C, 6A, 6B, 6C, 
               
               
                   
                   
                 7, 8, 9A, 14B, 15A, 15C, 15D, 16C, 16D, 
               
               
                   
                   
                 16E, 17A, 17B, 17C 
               
               
                 93 
                 muscle 
                 2A, 2B, 3A, 3B, 4A, 4B, 4C, 6A, 6B, 6C, 
               
               
                   
                   
                 7, 8, 9A, 14B, 15A, 15C, 15D, 16C, 16D, 
               
               
                   
                   
                 16E, 17A, 17B, 17C 
               
               
                 94 
                 bone 
                 2A, 2B, 3A, 3B, 4A, 4B, 4C, 6A, 6B, 6C, 
               
               
                   
                   
                 7, 8, 9A, 14B, 15C, 15D, 16D, 17A, 17B 
               
               
                 95 
                 anterior cortex 
                 2A, 2B, 3A, 3B, 4A, 4B, 4C, 6A, 6B, 6C, 
               
               
                   
                   
                 7, 8, 9A, 14B, 15A, 15C, 15D, 16D, 17A, 
               
               
                   
                   
                 17B 
               
               
                 96 
                 intraosseous space 
                 2A, 2B, 3A, 3B, 4A, 4B, 4C, 6A, 6B, 6C, 
               
               
                   
                   
                 7, 8, 9A, 14B, 15A, 15C, 15D, 16D, 17A, 
               
               
                   
                   
                 17B 
               
               
                 91 
                 posterior cortex 
                 2A, 2B, 3A, 3B, 4A, 4B, 4C, 6A, 6B, 6C, 
               
               
                   
                   
                 7, 8, 9A, 14B, 16D, 17A, 17B 
               
               
                   
               
             
          
         
       
     
         [0053]    The sternum, as shown in  FIG. 1 , is a flat, narrow bone comprising three segments, the manubrium, the gladiolus, and the xiphoid process. Each segment includes an intraosseous space bounded by compact bone. According to the present invention, the intraosseous space is the region where cancellous bone and the medullary cavity combine. Bone marrow includes blood, blood forming cells, and connective tissue found in the intraosseous space. For purposes of illustration, compact bone that is nearer to the anterior or dorsal surface shall be referred to as “anterior compact bone” or “anterior bone cortex” and compact bone that is farther from the dorsal or anterior surface shall be referred to as “posterior compact bone” or “posterior bone cortex.” 
         [0054]    According to one non-limiting embodiment, an apparatus of the invention may include (a) a driver operable to drive at least a portion of a tissue penetrator into the intraosseous space, (b) a tissue penetrator configured to penetrate the anterior cortex of a sternum, and (c) a depth control mechani sin operable to control the depth of penetration of the tissue penetrator into the sternum. For example, in some embodiments, the depth control mechanism may include a pressure-sensing tissue penetrator that transmits pressure changes on insertion to a sensor. The sensor then activates a trigger which in turn activates a motor or other mechanism to cause the tissue penetrator to insert into the intraosseous space a pre-selected depth. 
         [0055]    Devices of the invention may be configured in any convenient form. For example, in some embodiments, the tissue penetrator, driver, and depth control mechanism may be arranged in separate housings or bundled in a single housing. Housings of the invention may be formed in any suitable configuration including, without limitation, shapes like a cylinder, a barrel, a bullet, a carpenter&#39;s drill, a pistol, or any other convenient form. 
       Driver 
       [0056]    The driver provides power to the tissue penetrator. The power to penetrate the skin, muscle, and anterior cortex may be supplied to the tissue penetrator by any suitable means including, without limitation, one or more of the following: a battery, a spring, compressed gas, manual force, and any other mechanical or electrical source of rotation or reciprocation. The power may also be supplied directly or indirectly (e.g. using gears) by the operator and/or the patient. In addition to batteries, electric power may come from any other suitable source including conventional hospital or home wall outlets. The power source may be operably coupled with a motor. Motors of the invention may be selected from the group consisting of DC motors, AC motors, compressed gas motors, wound spring motors, and reciprocating motors. Motors of the invention may also be coupled to one or more gears, which may optionally be positioned in one or more gear boxes. 
         [0057]    According to the embodiment of the invention shown in  FIGS. 2A and 2B , driver  20  includes battery  21  and motor  22  that are electrically coupled and contained within housing  10 . Driver  20  also includes drive shaft  23  operably linked to motor  22 . Driver  20  further includes coupling end  24  attached to drive shaft  23 . Coupling end  24  in this and other embodiments may include a gear box, Similarly,  FIGS. 6A, 6B, 6C, 7   8 ,  9 A, and  14 B show other embodiments in which the driver may include like batteries, motors, and drive shafts. 
         [0058]    According to the embodiment of the invention shown in  FIGS. 3A and 3B , driver  20  includes spring  25  and coupling end  26  wherein spring  25  and coupling end  26  are connected and con tained within housing  10 . By contrast, according to the embodiment shown in  FIGS. 16A, 16B, 16C, 16B, 17A, and 17B , driver  20  includes spring  25  without a connecting member. Spring  25  may be directly or indirectly coupled to the closed-end of the housing fixing the position of that end of spring  25 . In some embodiments of the invention, coupling end  26  may further include a trigger mechanism for releasably holding spring  25  in a compressed “ready” position, a sensor for detecting pressure changes from the tissue penetrator and any other necessary relay circuit required to activate the trigger and or driver. 
       Tissue Penetrator 
       [0059]    Typically, a tissue penetrator will include an outer sheath, such as a needle and an inner trocar. Tissue penetrators of the invention may include in various combinations a needle, a needle set, a cannula, a trocar, a stylet, a catheter, or combinations thereof. Needles that are suitable for use in the present invention may be from about twenty gauge to about ten gauge. In some preferred embodiments, a tissue penetrator includes an outer needle or cannula and an inner trocar or stylet. In these embodiments, the trocar or stylet may prevent clogging of the needle by bone fragments during the drilling process. The tissue penetrator may include a needle set in which the component trocar and cannula are ground together to produce a matched set of a specific design to facilitate passage through bone. 
         [0060]    According to the invention, a tissue penetrator assembly includes a tissue penetrator. It may further include a collar, a connector, a hub, and combinations thereof. Collars of the invention, when present, may serve as depth control mechanisms. Connectors or hubs may serve as a means to connect an inserted catheter to a source of fluids or drugs including without limitation, blood, intravenous fluids of various formulations and any other fluid or medication suitable for intravenous administration. 
         [0061]    In some embodiments, a connector or hub may be any structure that supports or permits unidirectional or bidirectional access to the intraosseous space. Connectors may include one or more locking mechanisms to prevent accidental disconnections between a source of intravenous fluid and the inserted cannula. Connectors such as Luer locks may be male or female. In some preferred embodiments, a connector is a leer lock. 
         [0062]    According to the present invention, a tissue penetrator assembly may further include a hub with a flange to protect the skin and to stabilize the device after insertion into a human&#39;s sternum. The hub also provides a handle to remove the IO needle after use. The hub flange is the flat end of the hub that is nearer to the skin. Hubs may be made of any material, preferably a material that may be rendered sterile. 
         [0063]    In one specific embodiment, shown in  FIG. 14B  tissue penetrator assembly  30  includes connector  45 , hub  31  with flange  32 , screw  33 , cannula  41  and collar  43 . As shown, the stylet has been removed. 
         [0064]    In some embodiments of the invention, the tissue penetrator may be propelled into the IO space without rotation. This may be by direct manual force, or by a reciprocating action. In some embodiments, the needle may be rotated about its longitudinal axis in order to facilitate entry into the IO space. The needle may be rotated even where a driver including a spring is used. One way to rotate a spring-driven needle is to rotatably couple it with the housing. For example, a spring-driven needle may be fixedly attached to a coupling end having male threads on its outer circumference. This coupling end may be mated with a housing with corresponding female threads on its inner circumference. Consequently, as the spring propels the coupling end and attached needle through the housing, the coupling end would rotate. A swing may also be used to drive a tissue penetrator into the IO space by an impact force without rotation. 
         [0065]    As a further aid to IO entry, a small incision may be made in the patient&#39;s skin at the site where IO entry is desired. For example, if a collar is included with the apparatus, a skin incision will facilitate passage of the tissue penetrator to the bone. The incision may be formed using any suitable surgical blade, which may optionally form part of the tissue penetrator assembly. One or more blades may be included. Blades may be configured to be collapsible, removable, or retractable. 
         [0066]    For example, according to the embodiment shown in  FIG. 15B , retractable blade  34  is movably attached to opposite sides of cannula  41  in a plane parallel to the longitudinal axis of cannula  41 . As shown in  FIG. 15C , blade  34  may be used in a simple process to automatically form an incision in skin  92  at the proper place and of the proper size to permit ingress of tissue penetrator  40 , which includes cannula  41  and trocar  42 , and collar  43 . The initial incision may be made by the needle itself as shown in  FIG. 15A . The opposing blade configuration allows blade  34  to retract so that the drilling process may proceed after insertion. Retraction may be accomplished by actuating retraction lever  35  ( FIG. 15D ). Although not expressly shown, the opposing blade configuration may also allow the use of break-away blades that are removed after insertion, but prior to drilling. 
       Depth Control Mechanism 
       [0067]    According to the teachings of the present invention, sternal IO access devices may incorporate a mechanism to prevent over-penetrating the sternum, which could potentially damage underlying structures in the chest cavity. This mechanism may include mechanical stops, electrical stops, depth detectors, and combinations thereof. An electrical stop may prevent the operator from over-drilling by interrupting drill rotation and/or advancement when it detects that the needle tip has penetrated into the sternal IO space. An electrical stop may include a pressure-sensing tissue penetrator connected to a sensor that activates a trigger to control the driver such that a tissue penetrator is inserted to a pre-selected depth in the IO space. An electrical stop may also accurately detect the location of the cortex so that the tissue penetrator may be safely advanced to a predetermined depth in the IO space. An electrical stop may include a torque detector, an ultrasound probe, a mechanical probe, or a fluid detector. 
         [0068]    Mechanical stops include a preset drill depth (similar to a stop on a commercial drill), a collar attached to a needle or tissue penetrator, and a reverse clutch mechanism that prevents further drilling once the needle tip enters the intraosseous space of the sternum, Mechanical stops may have a fixed position or may be adjustable. If the mechanical stops are adjustable, they may be preset or adjusted while drilling is in progress. As shown in  FIG. 2 , annular stop  50  is a rib that traces the inner circumference of housing  10  and arrests advancement of tissue penetrator  40  by physically obstructing passage of coupling end  24 . In the embodiment shown in  FIG. 3 , annular stop  50  obstructs passage of coupling end  26 . Such physical stops may also be formed in any other suitable shape including, without limitation, arcs, bars, bumps, and ridges. Other options include a track including a groove of finite length on the inner surface of the housing and a corresponding ridge on the outer circumference of the coupling end. 
         [0069]    The embodiment shown in  FIGS. 14A and 14B  illustrates that the depth of needle penetration may also be controlled by forming an enlargement or ridge around (e.g. collar) the tissue penetrator. Collar  43  is preset at the desired distance from the needle tip to assure proper placement of the device. Collar  43  may be cylindrical with symmetrically beveled ends to promote easier entry through the skin as shown in the left side of  FIG. 14A  or any other suitable shape and configuration necessary to achieve its purpose. Alternatively, collar  43  may have a beveled proximal end and a sheer distal end as shown in the right side of  FIG. 14A . The acute angle or right angle of the distal end of collar  43  may promote a more secure stop against accidental over-penetration. The proximal end of collar  43  remains tapered to promote easy egress from the skin. 
         [0070]    Another non-limiting embodiment of a mechanical stop is a gear that engages ridges on the drive shaft ( FIG. 5 ) thus allowing depth control without interfering with rotation of tissue penetrator  40 . Gear  56  is rotatably coupled to suspension member  57 , which in turn is mounted on support  57 . As shown in  FIG. 5 , gear  56  is disengaged from ribs  55 . While not expressly pictured, gear  56  may contact and engage ribs  55  by any suitable mechanism. A gear of the invention may be configured to rotate a preset number of revolutions. Alternatively, the gear may be spring-loaded such that resistance increases with advancement, thereby creating a counter-balancing force to the driver. Devices with such gears may further reduce the possibility of penetrating or damaging the posterior cortex and underlying organs. A gear may also be operably linked to a sensor such that it may engage the drive shaft ribs  55  and stop needle advancement upon satisfaction of a pre-selected threshold. 
         [0071]    The invention also provides embodiments in which a reverse clutch mechanism is used to arrest bone penetration ( FIGS. 9-11 ). According to the embodiment of the invention shown in  FIG. 9A , drive shaft  23 , which is rotatably coupled with motor  21 , is fixedly connected to vertical clutch drive member  60 . Vertical clutch drive member  60  is releasably coupled to vertical clutch flywheel  61  by vertically engaging pin  62  ( FIGS. 9A and 9B ). Flywheel  61  is fixedly connected with tissue penetrator  40  such that withdrawal of vertically engaging pin  62  ( FIG. 9C ) interrupts the transfer of force from motor  21  to tissue penetrator  40 . Accordingly, tissue penetrator  40  may come to rest due to incidental frictional forces or an active breaking mechanism. 
         [0072]    As pictured, vertical engaging pin is spring loaded. Pin  62  may be configured to remain engaged only so long as lateral forces (torque) during the drilling process are maintained above a certain level. One may select or adjust the threshold torque required to maintain engagement, by selecting springs with a particular spring constant. As soon as the torque falls below this threshold, as it would when the needle penetrates the anterior cortex and enters the IO space, pin  62  withdraws, disengaging the driver. 
         [0073]    The reverse clutch mechanism may also be configured as concentric rings, one embodiment of which is illustrated in  FIG. 10 . In these embodiments, the drive shaft may be fixedly attached to a concentric clutch drive member. Concentric clutch. drive member  63  is releasably coupled to a concentric clutch flywheel  64  by horizontal engaging pins  65  and pawls  66 .  FIG. 10A  shows an embodiment of the invention in which horizontal engaging pins  65  are engaged and concentric clutch drive member  63  rotates flywheel  64 . Horizontal engaging pins  65  each include coil spring  67 . When the tip of the tissue penetrator  40  has entered the IO space, horizontal engaging pins  65  withdraw from pawls  66  such that concentric clutch drive member  63  can no longer rotate flywheel  64  ( FIG. 10B ). Flywheel  64  and its associated tissue penetrator may then come to rest due to incidental frictional forces or an active breaking mechanism. According to some non-limiting embodiments of the invention, horizontal engaging pin  65  may further include a leaf spring  68  that releasahly engages pawl  66  ( FIG. 11 ). Both coil spring  67  and leaf spring  68  may be configured to be torque sensors. 
         [0074]    Depth control mechanisms of the invention may include one or more depth sensors or probes, In one embodiment, depth sensors or probes may include pressure sensors. An example of this embodiment is shown in  FIG. 7 , wherein probes  70  are operably linked to coupling end  24 , which may contain a pressure sensor and a trigger. Pressure on the tips of probes  70  upon contacting bone is relayed to the sensor which activates the trigger. The trigger then starts advancement of tissue penetrator  40  by activating the driver ( FIG. 7 ). Tissue penetrator  40  may be advanced a preset distance calculated to place the tip of tissue penetrator  40  in the intraosseous space. Rotational forces (drilling), as opposed to impact forces, may be less traumatic on the bone and more precise in its application. 
         [0075]      FIG. 8  illustrates another non-limiting embodiment of a closely-fitting, cylindrical collar  44 , which encloses tissue penetrator  40  that may be used to locate anterior cortex  95 . Collar  44 , according to this embodiment, slides relative to tissue penetrator  40  along the longitudinal axis of tissue penetrator  40 . In its starting position, tissue penetrator  40  is recessed within collar  44 . As shown in  FIG. 8 , upon making contact with anterior cortex  95 , sliding collar  43  slides up into coupling end  24 , which activates motor  22  to drill a predetermined distance into the bone. Motor  22  may be rotational or reciprocating. More generally, sliding collar  43  may be used to activate a driver of any kind. 
         [0076]    Depth control using an IO device of the present invention may proceed in two stages as shown in  FIG. 4 . In the first stage, the needle may be advanced through the relatively soft tissues of the skin, subcutaneous tissue and muscle. In the second stage, the needle is drilled or driven through the much harder anterior cortex. 
         [0077]    According to the embodiment of the invention shown in  FIG. 4A , the device includes housing  10 , battery  21 , motor  22 , drive shaft  23 , tissue penetrator  40 , connector  45 , annular stop  50 , first penetration shoulder  51 , threaded annulus  52 , second penetration shoulder  53 , and third penetration shoulder  54 . The tissue penetrator assembly, according to this embodiment, includes tissue penetrator  40 , connector  45 , first penetration shoulder  51 , threaded annulus  52 , second penetration shoulder  53 , and third penetration shoulder  54 . The drive shaft may or may not rotate tissue penetrator  40  as it advances. Each annulus may include a pressure sensor, a trigger, or both a pressure sensor and a trigger. First penetration shoulder  51  is fixedly connected to threaded annulus  52  and drive shaft  23 , Second penetration shoulder  53  is rotatably mounted on threaded annulus  52 . Third penetration shoulder is slidably mounted on tissue penetrator  40 . As shown, the device is in its “ready” or undeployed position. 
         [0078]    The first stage of insertion is initiated when an operator contacts the device with the skin. Other activation methods are also possible. Upon contacting skin  92  and applying pressure, a first sensor activates advancement of the tissue penetrator assembly. As the tissue penetrator advances, third penetration shoulder  54  is stopped by annular stop  50 . The rest of the tissue penetrator assembly continues to advance such that second penetration shoulder  53  contacts third penetration shoulder  54  ( FIG. 4B ). Concurrently, the tip of tissue penetrator  40  con taus anterior cortex  95  as shown in  FIG. 4B . 
         [0079]    This contact together with continued application of pressure by the operator initiates the second stage by triggering a second sensor to activate motor  22 . Motor  22  then propels first penetration shoulder  51  the preset or operator-set distance to second penetration shoulder  53 . This, in turn, advances the tip of tissue penetrator  40  through anterior cortex  95  and into IO space  96  as shown in  FIG. 4C . 
       Depth Probes or Sensors 
       [0080]    Devices of the present invention may include various depth probes or sensors that detect the location of the needle, the bone, or both. Sensors are preferably connected to a control mechanism (e.g. a logic board) that determines whether needle advancement shall begin, continue, or terminate. Control mechanisms may also be mechanical or triggers. Sensor detection and controller evaluation may be intermittent, periodic or continuous. 
         [0081]    For example, an ultrasonic detector may be used to locate the sternal cortex. In the non-limiting embodiment, shown in  FIG. 6A , tissue penetrator  40  is in the storage or undeployed position. Ultrasonic sensor  71  detects the distance between the device (e.g. flange  12 ) and IO space  96 . Ultrasonic sensor  71  may also detect the position of tissue penetrator  40 .  FIG. 6B  shows tissue penetrator  40  in contact with anterior cortex  95 , ready for penetration. Detection by ultrasonic sensor  71  allows the device to tailor further advancement of the cannula to the exact dimensions of the targeted bone ( FIG. 6C ). This may be particularly advantageous given the variability from patient to patient and variations due to compression of skin and muscle by the device operator. This signaling process is outlined in the flowchart shown in  FIG. 61 ). Briefly, a sensor detects tissue penetrator, bone location, or both. This data is communicated to a logic board that measures or calculates the distance from the sensor to the bone. Upon obtaining this information, the driver is activated to advance the tissue penetrator the appropriate distance to achieve bone penetration. 
         [0082]    Bone cortex is very dense requiring considerable force to penetrate. As soon as the needle or drill passes through the cortex and enters the intraosseous space a pronounced change is noted in the force required to advance the needle. Resulting changes may be a decrease in torque and an increase in motor revolutions per minute (RPM). These changes can be measured and used to switch off the motor or activate a brake to prevent additional, potentially dangerous drilling activity. 
         [0083]    Thus, sensors of the invention may detect torque, revolutions per minute (RPM), backpressure, power consumption or any other relevant measure of needle advancement. in the embodiment shown in  FIG. 12A , the sensor is mechanically coupled to the motor and detects torque and/or RPMs and activates the switch. Thus, the sensor may be a shaft encoder. By contrast, the embodiment shown in  FIG. 1B  the sensor is coupled to the electrical circuit between the motor and the power source and detects amperage and/or voltage. 
         [0084]      FIG. 13A  illustrates the changes in torque or amperage as a function of drilling time or depth of penetration. At the time of penetration (P), the sensor may detect the decrease in torque or amperage and may discontinues needle advancement. If the needle is rotating, a brake may be applied to bring it to rest. 
         [0085]      FIG. 13B  illustrates the changes in RPM or voltage as a function of drilling time or depth of penetration. At the time of penetration (P), the sensor may detect the decrease in torque or amperage and may discontinues needle advancement. If the needle is rotating, a brake may be applied to bring it to rest. 
         [0086]    Probes and sensors of the invention may be operably coupled to a driver, a tissue penetrator, a depth control mechanism, or portions or combinations thereof. In one non-limiting embodiment the tissue penetrator itself may be or include a depth probe or sensor. 
       Reusable Handle/Disposable Cartridge 
       [0087]    The present invention provides intraosseous access devices with a reusable handle and a disposable cartridge containing the needle, one embodiment of which is illustrated in  FIG. 16 . The advantage of these devices over currently available devices is the overall size and weight reduction of carrying multiple devices in the field, such as in the medical pack by army medics. Ten (10) units of currently disposable IO devices weigh far more and take much more space than one reusable handle with 10 disposable needle assemblies. The greater part of the weight and size may be in the reusable handle. Reusable handles may contain a driver in accordance with the teachings of the present invention. Disposable cartridges may include tissue penetrator assemblies and depth sensors in accordance with the teachings of the present invention. Disposable cartridges of the invention ma engage or lock into the reusable handle with a recess and detent or any other mechanism, 
         [0088]      FIG. 16A  illustrates an embodiment of an IO device of the invention including reusable handle  19  and disposable cartridge  15 . This figure shows the handle separate from cartridge  15  as seen prior to connecting for use. Cartridge  15  includes tissue penetrator  40 , probes  70 , detent  16 , coupling member  13 , and end member  14 . Cartridge  15  further includes releasable needle shield  18 . Tissue penetrator  40  and probes  70  are covered by needle shield  18  to protect the user from accidental needle sticks and preserve tissue penetrator  40 . Shield  15  may have a domed surface as shown or a flat surface to allow the cartridge to stand alone. While not shown in the figure, cartridges of the invention may further include, without limitation, hubs, flanges, screws, and bolts. 
         [0089]    Reusable handle  19  includes housing  10 , spring  25 , and engaging lock  17 . Engaging lock  17  engages detent  16  upon insertion of cartridge  15  into handle  19 . As a result, cartridge  15  may “pop” or snap into reusable handle  19  ( FIG. 16B ). Although not expressly pictured, cartridge  15  and handle  19  may include a locking mechanism that is engaged by twisting cartridge  15  into handle  19 . Needle shield  18  may be removed when ready for use ( FIG. 16C ). Deployment of tissue penetrator  40  is similar to that described for other embodiments. See e.g.  FIG. 8 . Briefly, compressed spring  25  is released upon probes  70  contacting anterior cortex  95 . As spring  25  expands, it propels tissue penetrator  40  through anterior cortex  95  and into intraosseous space  96  ( FIG. 16D ). Thereafter, reusable handle  19  may be removed and a access to intraosseous space  96  may be gained through connector  44  ( FIG. 16E ). Spring  25  need not contact connector  45 , but may contact a plate or other structi on (not expressly shown) that drives tissue penetrator  40  into bone  94 . 
         [0090]    As shown in  FIG. 17A , a driver (here spring  25 ) in accordance with the invention is shown in the undeployed, ready position. Contact with skin  92  may activate the spring  25 , which causes tissue penetrator  40  to penetrate skin  92 , muscle  93 , and proximal cortex  95 . Advancement of tissue penetrator  40  continues until collar  42  contacts proximal cortex  95  (MG.  17 B). Thus, according to this embodiment, flange  32  acts as the depth control mechanism. Other depth control mechanisms may also be employed such as a probe, sensor, rib and any combination thereof. Once advancement is arrested, the end of tissue penetrator  40  is positioned in intraosseous space  96 . 
         [0091]    The reusable handle, which here includes housing  10  and spring  25 , may be removed leaving tissue penetrator assembly  30  behind ( FIG. 17C ). Tissue penetrator assembly  30  includes hub  31  to provide stabilization of tissue penetrator  40  against the skin and to provide for additional security against accidental advancement or dislodgement during patient transport. Hub  31  incorporates a flange  32  at its distal end to provide for skin safety and better stabilization. After insertion of tissue penetrator  40  into the IO space hub  31  is adjusted by screw  33  or other mechanism so that it snuggly fits against the skin. Tissue penetrator  40  may be fixedly attached to screw  33  either before insertion or after insertion (e.g. by a locking mechanism). IO space  96  may then be aseptically accessed through connector  45 . 
       Methods 
       [0092]    One aspect of the invention is a method of establishing access to the intraosseous space including contacting the skin covering the manubrium of a subject with a device including a driver, a tissue penetrator, and a depth control mechanism, deploying the tissue penetrator. The term “subject” may include any vertebrate with a sternum. The term “operator” may include anyone who uses a device of the invention including, without limitation, a. health care professional and the subject. The term “deploying the tissue penetrator” may mean advancing the tissue penetrator from its starting position a sufficient distance to situate the tip of the tissue penetrator in the IO space. The method may further include detaching the driver from the tissue penetrator after insertion of the tissue penetrator is achieved. 
         [0093]    For example, according to the embodiments pictured in  FIGS. 2-3 , the operator inserts tissue penetrator  40  into the subject at the region shown in  FIG. 1 . Tissue penetrator  40 , which includes a pressure sensor, detects the increase in pressure that occurs when the tip contacts anterior cortex  95 . The sensor then activates driver  20  to advance tissue penetrator  40  until coupling end  24  ( FIG. 2 ) or coupling end  26  ( FIG. 3 ) contacts annular stop  50 . While not expressly shown, a connector recessed in the coupling end may be used to access IO space  96 . This access may optionally involve removal of portions of the device, such as housing  10 , driver  20 , driver shaft  23 , and coupling end  24  or  26 . 
         [0094]    In a related embodiment shown in  FIG. 5  tissue penetrator  40  includes a pressure-sensor (not expressly shown). Upon application of an axial force by the operator against the subject&#39;s sternum, tissue penetrator pierces the subjects skin, muscle, and subcutaneous tissue to contact bone. The sensor either directly or indirectly activates motor  22  to rotate tissue penetrator  40 , thereby beginning drilling into the bone. Simultaneously or subsequently, gear  56  may engage ribs  55  to regulate the depth of drilling. For example, upon detecting a drop in pressure, the sensor may directly or indirectly brake or block further rotation of gear  56 . 
         [0095]    Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alternations can be made herein without departing from the spirit and scope of the invention as defined by the following claims.