WO2002096497A1

WO2002096497A1 - Intraosseous method and apparatus

Info

Publication number: WO2002096497A1
Application number: PCT/AU2002/000673
Authority: WO
Inventors: David George Noble
Original assignee: David George Noble
Priority date: 2001-05-29
Filing date: 2002-05-27
Publication date: 2002-12-05
Also published as: AUPR529101A0

Abstract

A method for the oxygenation of blood via the intraosseous route is disclosed in which a gas containing oxygen is introduced into the cavity of a bone of a human or animal patient. Connectors (14) having sealing means (16) for insertion in a hole in a bone (10) and for use in the intraosseous infusion of gas or liquid under pressure are disclosed. Apparatus for effecting the oxygenation of blood and for the introduction of liquid via the connector (14) is also disclosed. In one example, a gas supply and regulator (30) supplies gaseous oxygen via a two-way valve (44) to the connector (14) and a liquid supply and regulator (32) supplies liquid to the valve (44) for alternate introduction into the bone (10). The flow of gas and liquid may be controlled by physiological parameters, such as blood oxygenation, gas bubbles, blood pressure and blood lactate, using appropriate monitors or detectors (31, 33, 35, 37). Examples of suitable connectors for use with the method and apparatus of the invention are disclosed.

Description

TITLE: INTRAOSSEOUS METHOD AND APPARATUS

TECHNICAL FIELD

This invention relates to methods and apparatus for intraosseous infusion of fluids into the vascular systems of humans and animals. It is particularly, but not exclusively, concerned with the oxygenation of blood by intraosseous infusion.

BACKGROUND TO THE INVENTION

The intraosseous route for liquid infusion into the vascular system of humans and animals has been known and used for at least 50 years. In this technique, a hole is punched, formed by a self-tapping screw or drilled into the cavity of a readily accessible bone, such as the tibia or the sternum, and a clinically appropriate liquid is injected into the cavity via the punch, screw or drill, which is retained in the bone by screw threads, friction or by pressure exerted by the surgeon. Prior clinical usage of intraosseous infusion has been reserved for cases where the patient is in extremis, the peripheral vascular system has shutdown (or is difficult to access as in trauma victims, infants or other paediatric patients), or there is a strong likelihood that a sudden infusion of liquid into a major vein will dislodge clots, restart bleeding or cause a heart attack or brain or lung damage. In this situation it is not surprising that the art pays little attention to leakage of the infusate from the hole formed in the bone.

US patent No. 5,938,636 to Kramer et al discloses an auto-infuser capable of sustaining either the low pressure used for intravenous infusion or the much higher pressures necessary for intraosseous infusion of liquids over an extended (but unstated) period of time. [It is noted that an earlier US patent 5,868,711 issued to Kramer et al disclosed the use of a 'smart' controller that was said to be suited to the intraosseous infusion of liquids.] In US patent 5,938,636, Kramer et al suggest that infusion can be regulated by monitoring any one of a variety of physiological parameters such as blood pressure, cardiac output, blood lactate or blood or tissue oxygenation, though the use of an oxygenating infusate was not disclosed or suggested. There was also no discussion of the system or patient complications caused by leakage of infusate from the infusion site during sustained delivery from a pump regulated by a monitored physiological parameter.

US patent 6,187,744 to Rooney appears to be first to disclose the intravenous infusion of oxygen-containing liquid biocolloids to serve as haemodiluents, blood substitutes, plasma expanders or resuscitative liquids. Such liquids, it was suggested, can be used to regulate the oxygenating activity of haemoglobin. In passing, Rooney mentions that these oxygenating compositions could be delivered via the intraosseous route, though no further detail or examples are provided.

While a variety of devices for accessing the interior of a major bone for the purpose of intraosseous infusion or bone marrow transplantation are known in the art, most can be described as screw-threaded self-tapping metal needles or cannulae. Examples are US patents 6,210,376, 5,601 ,559, 5,554,154,

5,484,442, 5,431 ,655, 5,372,683 and 4,969,870. In other cases, unthreaded metal needles or cannulae are employed; for example, US patents 6,183,442, 5,868,711 , 5,817,052 and 5,368046. The needle of US patent 6,183,442 is rotated by a hand-held motor while those of US patents 5,868,711 4,696,870 are impact-driven and rotated.

There a strong tendency for self-tapping needle and cannular devices to either strip the thread being cut in the bone or to cut a thread that is a sloppy fit for the needle or cannular thread. In either case, infusate leakage will result. Similarly, it is difficult to rotate an unthreaded needle and cannula without cutting a hole that is too large. While impact-driven needles are more likely to provide an effective seal, the depth of penetration is difficult to control and, if an effective seal is obtained, it is difficult to extract the needle when the procedure is complete.

In summary, because intraosseous infusion has been seen as a short-term, life- saving emergency procedure, the prior art has not adequately addressed the problem of leakage of the liquid infusate from the hole in the bone. However, long-term automated intraosseous infusion techniques are now being proposed in the art without necessary attention to infusate leakage. When the matter of leakage has been addressed - as in US patent 5,372,583 - it is simply recommended that pressure be applied in the vicinity of the infusion site "to compress the skin, flesh and bone". But the pressure on the skin needed to prevent leakage around a needle or cannula is likely to stop blood supply to the underlying flesh with serious consequences if infusions take longer than a few minutes. It is also to be noted that the critical need of many patients in extremis for rapid blood oxygenation has been poorly addressed in the art.

OBJECTIVES OF THE INVENTION

It is therefore an object of the present invention to provide improved means for intraosseous infusion that will not be subject to one or more of the disadvantages indicated above.

OUTLINE OF INVENTION

From one aspect, the invention comprises an intraosseous infusion technique in which a biologically active gas is introduced into a bone cavity. From another aspect, the invention comprises the intraosseous infusion of gaseous oxygen into the interior of a bone of cavity; or, more particularly, a method for the in vivo oxygenation of blood in a human or animal patient characterised by the steps that introduce a gas comprising biologically active oxygen into the cavity of a bone of the patient. The method may include the step of boring a hole through the wall of the bone to access the bone cavity, fitting a tubular connector into the hole in a substantially gas-tight manner and introducing the gas into the bone cavity via the connector.

From another aspect, the invention relates to tubular connectors for use in intraosseous infusion techniques (whether using a gaseous or liquid infusant) having deformable sealing means adapted to facilitate the formation of a hermetic seal between the connector and the periphery of a hole in a bone. For example, the sealing means may comprise an external annular surface on the connector that is resiliently deformable and thereby adapted to conform to the periphery of the hole to facilitate the formation of the seal. The sealing means is preferably formed from biologically compatible elastomeric material, which can be formed as a ring, a liner or over-moulding, outer liner or slip-on tube covering portion of the exterior of the connector. However, it is also envisaged that the entire connector may be moulded from such material.

The sealing means may include deformable, outwardly extending fins and the method may include the step of pushing the connector into the hole in the bone to thereby elastically deform the fins against the periphery of the hole so to effect or augment the seal between the connector and the hole. The fins or flanges may be of helical form so that, while insertion might be achieved without rotation, removal of the connector can be assisted by rotation in the 'unscrewing' direction. Thus, the method may include linear insertion of a connector for intraosseous infusion and rotary removal thereof.

The sealing means may comprise a thin and deformable, outwardly extending, continuous washer-like terminal fin on the distal (or inner end) of the connector so that, after insertion of the connector, the terminal flange will unfold or expand to lie near or against the inner surface of the bone wall and thereby assist in the formation of the desired seal.

The connector may include means to actuate the sealing means after the sealing means has been placed in the hole in the bone, for example by compression of an elastomeric sealing means in the axial and/or radial direction (with respect to the hole) so that it is compressed between the wall of the hole and the remainder of the connector. Part of the connector may be moved to axially compress the elastomeric sealing means causing it to bulge or expand radially against the wall of the hole. In addition or alternatively, movement of part of the connector can exert direct radial pressure on the sealing means to compress it radially against the wall of the hole.

It will be appreciated that, while the connectors indicated above are well suited to the introduction of gas into a bone cavity under pressure, they are also well suited for use for the introduction of liquids into the bone cavity in conventional intraosseous techniques. Indeed, in some patients it will be necessary to infuse both liquid and oxygenating gas into a bone to effect balanced restitution of blood function. From another aspect, therefore, the invention involves an intraosseous infusion technique in which a source of a liquid infusate and a source of an oxygenating gas are connected by separate lines to a single device implanted in the bone of a patient and wherein the liquid and gas are fed together or alternately into the bone under the control of an electronic control means. Indeed, one or more physiological parameters can be monitored to regulate the flow of the liquid infusate and one or more physiological parameters may be monitored to regulate the flow of the gaseous infusate.

With respect to gaseous oxygenation via the intraosseous route, it is desirable to employ a relatively high rate oxygen supply while blood oxygenation is well below normal and to taper off the rate of supply as blood oxygen levels approach normal. Arterial blood oxygen saturation can therefore be monitored to achieve this regulation. As a precaution against grossly excessive oxygenation, it may be desirable to detect the presence of gas bubbles in a vein or in a chamber of the heart and to trigger an alarm and/or cut off or reduce gas flow to the bone in the event that gas bubbles are detected. Other physiological parameters related to blood oxygenation may be more readily accessible and less intrusive, but they may not be so accurate or reliable as arterial blood oxygenation. For example, a simple optical peripheral perfusion monitor using a colour-sensitive light detector could be employed.

It is conceivable that gross bubbles of oxygen could form in a vein and accumulate in the right ventricle where the supply of intraosseous oxygen is grossly excessive. This is because micro-bubbles of oxygen can enter the marrow capillaries, venules and veins of the patient in the event that blood in the veins is devoid of deoxy-haemoglobin (i.e., oxygen saturated). The unreacted micro-bubbles may then coalesce to form larger bubbles and the gas may, depending upon the degree of oxygenation of the venous blood being returned from other parts of the body, accumulate in the right ventricle and impair heart function. DESCRIPTION OF EXAMPLES

Having broadly portrayed the nature of the present invention, particular examples will now be described by way of illustration only. In the following description, reference will be made to the accompanying drawings in which:

Figure 1 is a schematic partial longitudinal section of a human tibia under going intraosseous infusion by a method and apparatus of the invention.

Figures 2A and 2B are, respectively, perspective views of the connector of the first example taken from below and above, while Figure 2C is a sectional elevation of the device of Figures 2A and 2B taken on section line 11-11 of Figure 2A and shown in place in a patient's bone. A tool for inserting and removing the device is also shown in Figure 2A.

Figures 3A - 3E is a series of sectional diagrams showing stages in the deployment of the device of the first example.

Figures 4A and 4B are, respectively, a perspective and a side elevation of the connector of the second example.

Figures 5A to 5C is a series of sectional diagrams showing stages in the deployment of the device of the second example.

Figure 6 is a sectional side elevation of a device of the device comprising the third example implanted in a bone.

Figure 7 is a side elevation of a device comprising the fourth example of a connector formed in accordance with this invention.

Figure 8 is an enlarged sectional elevation of the connector device of the fifth example. Figures 9A - 9E is a series of sectional diagrams showing stages in the deployment of the device of the fourth example.

Figures 9A and 9B are sectional elevations of two variants of a device comprising the fifth example.

Figures 10A and 10B are, respectively, a sectional elevation and a side elevation of the device comprising the first variant of the sixth example.

Figures 10A and 10C are, respectively, a sectional elevation and a side elevation of the device comprising the first variant of the sixth example, while Figures 10D and 10E are similar views of the second variant of the sixth example.

Figures 11 A - 11 F is a series of diagrams illustrating stages in the deployment of either variant of the sixth example.

Figure 1 illustrates, in highly diagrammatic fashion, portion of the tibia bone 10 of an adult human undergoing the intraosseous infusion of oxygen gas and a clinically appropriate liquid through a small diameter tube 12 and a button-like connector 14 that has been pushed through a hole bored in the wall of bone 10, connector 14 being formed from an elastomeric material and having deformable sealing means 16. Connector 14 can be readily made small enough for subcutaneous implantation. Tube 12 is bonded into connector 14 and emerges from the side of the connector so that it will lie easily against the skin of the patient.

The interior of bone 10 contains venous venules 18 that drain to a vein 20 leading from the bone, arterioles 22 supplied by an artery 24 and a capillary network matrix 25 connecting arteriole to venule. Gaseous oxygen introduced into the matrix 25 via tube 12 and connector 14 is shown as small bubbles 28. The oxygen diffuses into the plasma within capillary matrix 25 crossing the semipermeable membrane of the capillaries along a concentration and pressure gradient. Here, the haemoglobin of the red blood cells reversibly binds the oxygen as the red blood cells pass through capillary matrix 25. The binding of oxygen to the haemoglobin reduces the oxygen tension of the surrounding plasma in matrix 25, maintaining the oxygen concentration and pressure gradient across the capillary wall.

It will be seen that the uptake of oxygen in this way is very much like the uptake of oxygen in the lungs of a human. The action is clean and rapid and does not depend upon the breakdown of a liquid carrier as required by the art. Biologically compatible liquids are necessarily very inefficient as carriers of oxygen in comparison with the gaseous oxygen.

It is, of course, appreciated that patients in extremis may need to have their blood/plasma volume augmented and to receive other physiologically appropriate substrates apart from or as well as oxygen. This need can be accommodated by coupling both a liquid infusion pump or flow-regulator 30 and a gas infusion pump or flow-regulator 32 to connector 14 via a Y-junction 34 connected to the tube 12. Preferably, non-return valves 36 and 38 are fitted in lines 40 and 42 from liquid flow-regulator 30 and from gas flow-regulator 32 (respectively) to prevent undesirable back-flow of liquid or gas. Y-junction 34 may incorporate a two-way valve operable by lever 44, to effect the selection of either gas or liquid for delivery.

Those skilled in the art will appreciate that the employment of valve 44 can obviate the need for non-return valves 36 and 38 and that the operation of flow- regulators 30 and 32 and of valve 44 can be effected under microprocessor control to ensure that a preset cycle of liquid and gas infusion is maintained and that preset rates of liquid and gas are maintained in each cycle. It will also be appreciated that, with due care, both liquid and gas can be fed via the intraosseous route simultaneously and, if desired, substantially continuously, whether to the same or different bones, or to the same or different connectors in the same bone.

Since it is desirable to vary the feed of intraosseous gas and/or liquid according to the patient's immediate physiological need, monitors and alarms may be connected to regulators 30 and 32. In Figure 1 , an arterial blood-oxygen saturation monitor 31 and a gas bubble detector 33 are shown connected to gas regulator 30, and a blood pressure monitor 35 and blood lactate monitor 37 are shown connected to liquid regulator 32. The latter monitors are known in the art and have been disclosed by Kramer (supra) and others. The monitoring of blood oxygen saturation, for example by indwelling arterial catheters or by simple optical peripheral perfusion monitoring devices, is also a known technique. While the detection of gas bubbles in the venous system or in a chamber of the heart - for example by ultrasonic methods - is also known, the detection of gas bubbles can signal a serious problem and may be used as an alarm and to shutdown, or at least reduce, gas supply to the bone.

Referring more particularly to Figures 2A - 2C, connector 14 has a proximal button-like top part 48 and a distal cylindrical bottom part 50 of smaller diameter than top part 48 extending downwards therefrom. Connector 14 may be conveniently moulded from plastic material such as a bio-compatible nylon, which is strong and rigid in thick section but flexible and deformable in thin section. A pair of under-cut tool sockets 52 are moulded into the upper surface of top part 48 to take the feet 54 of a bifurcated tool 56 used to insert and remove the device. Connector 14 has an internal bore having a lower portion 58a that is concentric with bottom part 50 and an upper portion 58b that is almost at right angles to lower portion 58a and is arranged so that it opens into one side of top 48. The end of tube 12 (omitted in Figures 2A and 2B) is glued or welded into the side bore opening 58b (by techniques well known in the art) so as to form a secure hermetic seal with top part 48.

In this example sealing means 16 comprises (i) a thin helical fin 60 formed around the exterior of tubular bottom part 50 and (ii) a radial washer-like sealing flange 62 on the distal end of part 50 of a similar outer diameter to fin 60, both fin 60 and sealing flange 62 being moulded integrally with connector 14. Fin 60 and sealing flange 62 are thin and readily deformable so as to be adapted to form a fluid tight seal with a drill hole of appropriate size in a bone. While two or more helical fins may be employed (forming multiple helixes) I have found that a better seal results from the use of a single helix with a rather small helix angle (eg, 5-15°). In this example, it is assumed that the helix is right-handed so that, when connector 14 is rotated clockwise with respect to the user, it will tend to screw into the hole in a bone and, when it is rotated anticlockwise, it will tend to screw out of the hole.

One method of deploying and removing connector 14 is illustrated by the steps shown in Figures 3A to 3E. First, the target site over bone 10 is disinfected and an incision 72 is made with a scalpel 73 in the overlying flesh 74 (Fig. 3A). Then a clean-sided hole 76 is drilled in bone using a drill bit 78 fitted with a depth-stop 79 (Fig. 3B) rotated by a motor (not shown) at the optimum speed for forming a clean-sided hole. After withdrawal of drill bit 78, connector 14 and bonded tube 12 are removed from a sterile pack (not shown) and coupled to the bifurcated tool 56 using sockets 52. Tool 56 is then used to first align lower part 50 of connector body 14 with hole 76 and then push it into hole 76 - without rotation - thereby forcing sealing flange 62 and helical fin 60 to fold back or flatten themselves against the wall of hole 76 (see Fig. 3C). When connector 14 is pushed home (Fig. 3D), sealing flange 62 clears the inner face of the wall of bone 10 and unfolds to form a secondary seal, the primary seal being the tightly folded fin 60. Tool 56 is, of course, removed. [Note that, for clarity, helical fin 60 is shown with fewer, thicker and larger turns 60 than might be desirable in practice.]

After sufficient infusion has taken place, tube 12 is heat-sealed and cut and the feet 54 of tool 56 are re-inserted into sockets 52 on top 48 of connector 14. Tool

56 is then rotated slightly in the unscrewing (anticlockwise) direction to secure it in the undercuts of sockets 52. It is then turned with more force and pulled at the same time so as to both unscrew and pull connector 14 from hole 76 in bone 10. Fin 60 will act like a screw thread allowing the connector to be removed without inverting and jamming fin 60 in hole 76 of bone 10. Sealing flange 62 will be inverted as it is pulled into hole 76 and, because of its thin and deformable character will present little resistance to the removal of the connector 14.

If desired, sealing means 16 may be formed on lower part 50 of connector 14 from a different material than that of the rest of the connector by using, for example, an over-moulding process. Alternatively, fin 60 and sealing flange 62 can be moulded onto a separate elastomeric sleeve that is fitted over the bottom portion 50 of connector 14 and glued or otherwise fixed in place. It is also envisaged that the sealing means 16 may employ a series of radial fins instead of one or more helical fins.

The connector 100 of the second example will now be described with particular reference to Figures 4A and 4B. Connector 100 is essentially an open-topped tube 102 in which the open top is in the form of a male Luer coupling 104 and the closed bottom carries a metal cutter or drill point 106. An external radially extending collar 108 is fixedly located on tube 102 between coupling 104 and drill point 106 and a central bore 110 extends from coupling 104 to drill point 106. As in the first example, a pair of undercut slots 112 is formed in the upper face of collar 108 to take the ends of a bifurcated tool (not shown). A disposable protective cap 114 is screwed onto Luer coupling 104 and is only removed immediately before the fluid supply line is connected. At least one lateral or transverse hole 116 is formed in the bottom portion of tube 102 just above drill point 106, and/or in the point itself, so as to serve as outlets for fluid in tube 102.

In this example, the sealing means of connector 100 comprises a sleeve-like pliable moulding 120 of bio-compatible elastomeric plastic material that has a radially extending upper flange-like disc 122 and a lower tubular portion 124. A thin helical sealing fin 126 is formed on the outer cylindrical surface of moulding

120, fin 126 being of similar form and function to fin 60 of the first example and (as noted in the first example) may comprise a series of radial fins if desired. A bottom washer-like flange 128 is also formed on moulding 120, as in the first example. If connector tube 102 is formed from metal, moulding 120 is preferably formed by over-moulding directly onto tube 102 below collar 108 and above drill point 106 so that disc 122 adheres to the bottom of the collar and the tubular portion 124 adheres to the outside of tube 102. Alternatively, the entire device except for drill point 106 can be formed from suitable plastic material.

The use of connector 100 will now be described with reference to the parts of Figure 5. Tool 123 is coupled to connector 100 by fitting its ends into slots 112 and deploying the combination like a trocar. Tool 123 maybe rotated by hand or by the use of a suitable motor. In this way, the connector 100 is driven directly through the flesh 132 of a patient and into the wall of a bone 134 (Fig. 5A). As the connector proceeds through the bone wall, sealing washer 128 will fold back (as shown in Fig. 5a and as described in the previous example).

Once connector 100 is at the correct depth, tool 123 is uncoupled, protective cap 114 is removed, a delivery tube 136 is coupled onto male Luer coupling at the top of connector tube 102 using a female Luer coupling 138, and infusion is commenced (Fig 5B). Leakage of the infusion fluid from the hole 139 formed in bone 134 is prevented (as before) by radial flange 128 and fins 126 of moulding 120 (which together form the sealing means in this example). After infusion has finished, tube 136 is heat-sealed near coupling 138, tool 123 is re-engaged with slots 112 in collar 108 and coupling 100 is pulled and unscrewed from bone 134 (Fig. 5C) in the same manner as in the first example.

The third example is of a connector (150) that is particularly suited for the delivery of oxygen gas into a bone of a child because it is adapted for manufacture in small sizes and for implantation. The central lumen of the device can be less than one millimetre in diameter and its length need be no more than a few millimetres. Connector 150 is illustrated in Figure 6 and simply comprises tubular sealing means 152 moulded from a suitable bio-compatible elastomeric material and a rigid needle-like pipe or sleeve 154 formed from plastic or metal. Sealing means 152 has an upper flange part 156 and a lower cylindrical tubelike part 158. Lower part 158 is pushed into a pre-drilled hole in a bone 160, after the flesh and skin 162 have been cut and pulled clear of the site. Rigid pipe or sleeve 154, which is preferably bent nearly at right angles, is then pushed into sealing means 152 to expand the lower part 158 firmly against the wall of the hole in bone 160, pipe or sleeve 154 being connected to a flexible infusion tube 164. After insertion of pipe or sleeve 154, the flesh and skin 162 can be returned to cover the tubular sealing means 152 of connector 150. To remove connector 150, the skin and flesh 162 is again parted, pipe or sleeve 154 is pulled from sealing means 152 to relieve the compression on the tubular sealing means 152 and thereby facilitate its removal from bone 160.

The connector 200 of the fourth example is shown in Figure 7 and, while it can also be readily made in small sizes, it is self-drilling. Connector 200 comprises a hollow tubular metal body 202 with a distal end 204 formed as a cutter and a proximal end 206 that is bent nearly at right angles to the distal end 204 and carries an enlarged taper 208 for direct connection to flexible, small-diameter medical tubing 210. Two annular grooves 212 are formed around body 202 and a miniature elastomeric O-ring 214 is fitted into each groove. However, in some cases there will be advantage in using a shorter body 202 with only one O-ring. Thus O-ring(s) 214 comprise the sealing means of the device. A collar 216 is mounted on body 202 at or near the bend between ends 204 and 206 in order to provide a limit stop for insertion of distal end 204 into a bone (not shown) and to provide means for securely mounting connector 200 into a tool (not shown). A similar bifurcated tool to those described in the previous examples may be used and, for that purpose, undercut recesses 218 are formed in the upper face of collar 216. If desired, collar 216 can be mounted in such a fashion that it can slide on tubular body 202 so that it can be fixed in a variety of positions to act as an adjustable depth stop (though this option is not illustrated).

As supplied, connector 200 may be fitted with disposable plastic caps (not shown) on its distal and proximal ends. The connector is fitted into a suitable tool, the cap on the cutting distal end is removed and the cutting end presented to the target bone. The tool is then operated to drive the distal end of the connector through the wall of the bone and into the bone cavity, bringing at least one O-ring 214 into contact with the wall of the hole and collar 216 into contact with the skin or bone. The tool is then uncoupled from the connector 200, the protective cap on the proximal end is removed, a small diameter medical tube 210 is pushed onto taper 208 and a source of gas under pressure is connected to the tube.

While the distal cutting end of connector 200 will tend to cut a core from the bone, it is unlikely that the core will remain intact because of its small diameter. Instead, I have found that the removed bone material usually fragments in the bore of connector tube 202. In any event, application of gas pressure to tube 202 will readily drive out any core or debris into the bone cavity. After infusion is complete, the flexible tube is sealed and severed and the tool is again coupled to the connector and used to pull (with or without rotation) the connector from the bone.

Instead of using loose O-rings 214 as the sealing means of the fourth example, elastomeric sealing rings may be moulded into grooves in the tubular connector body 202, or even moulded directly onto an un-grooved surface of body 202. The rings may take the form of fins or may be of half-round, triangular or other suitable section.

The fifth example of a connector (300) is illustrated in the greatly enlarged sectional diagram of Figure 8 and various stages of its deployment are illustrated in Figures 9A to 9E. In these Figures, a dedicated hand-tool 301 for use with connector 300 is also shown, it being convenient to mould tool 301 from suitable plastics material.

Connector 300 comprises an open-ended tubular metal body 302 of circular section, a movable collar 304 moulded from plastic mounted on body 302 and a tube 306 of elastomeric material fitted around body 302 below collar 304, tube 306 serving as the sealing means of this example. The top of body 302 is formed as the male part 308 of a Luer or similar coupling. The intermediate portion of body 302 (below coupling part 308) has a plurality of annular ratchet- teeth 310 and 312 formed in its outer surface, the uppermost annular ratchet tooth 310 faces upwards while three lower annular ratchet teeth 312 face downwards. The portion of tubular body 302 located below lower teeth 312 has a smooth cylindrical outer sur ace that terminates in a bottom extremity 316 that is radially enlarged and formed with cutting teeth 318 on the bottom and sides thereof.

Collar 304 is preferably of a circular shape (in plan view) and has two opposing catches 320 on its upper face. Catches 320 are moulded integrally with the collar and have inwardly facing detents 322 adapted to engage any of ratchet teeth 312 and 310, depending upon the axial position of collar 304 along body portion 302. The catches 320 are joined to the rest of collar 304 with sufficient flexibility as to allow their outer ends to be manually bent downwards to effect disengagement of detents 322 from any of ratchet teeth 310 and 312. Detents 322 and tooth 310 are shaped so that collar 304 cannot move downwards on body 302 past tooth 310 without manual release of catches 320 and so that collar 304 cannot move upwards on body 302 past any of teeth 312 without manual release of catches 320 and associated detents 322.

Preferably, the enlarged outer portion of lower extremity 316 of body 302 is provided with an upwardly facing peripheral skirt 324 that forms an upwardly facing recess in which the bottom of sealing tube 306 can be fitted and secured by crimping or rolling skirt 324. The upper extremity of sealing tube 306 is preferably secured firmly to the bottom of collar 304. This may be done by forming an outwardly extending flange 326 on the upper end of tube 306 and heat-bonding or gluing the flange 326 to the bottom of collar 304. This not only fixes the upper end of tube 306 to collar 304 (for the purpose to be describe below) but it provides the advantage of a soft interface between the collar and the flesh or bone of the patient.

Conveniently, connector 300 is pre-assembled and sterile-packed with a simple hand-tool. In this example, the hand-tool is shown at 301 and basically comprises a hand-knob 352 that is joined to a hollow bell-shape socket 354 by a drive shaft 356. A female Luer coupling 358 is formed in the lower interior portion of socket 354 to take the male part 308 on connector body 302, and a square- section socket 360 is formed in the upper interior portion of bell-like socket 354 to take the corresponding square shank 362 of a drill bit 364. When female Luer part 358 is engaged with male part 308 the point 366 of bit 364 extends the appropriate amount from the bottom of tubular body 302 (as shown in Figure 8).

Drill bit 364 is prevented from falling out of connector 300 because its square shank 362 cannot fit through the bore of body 302.

Referring now to Figures 9A - 9B, the connector 300 and coupled tool 301 have been removed from their sterile packing. An incision is made in the skin 370 at the site and tool 301 is used to drill through the bone 372 by rotating it, the drill bit 364 and the entire connector 300 in unison while applying pressure (Fig. 9B).

After the wall of the bone has been penetrated and the enlarged distal end 316 is clear of the inside wall of bone to the desired degree, tool 301 is held in one hand and upward pressure exerted_while collar 304 is pushed down with the other hand to snap detents 322 over teeth 312 on body 302 until the collar reaches the flesh 370 (or bone 372) of the patient (Fig. 9C). This causes elastomeric tube 306 to thicken and buckle to tighten and hermetically seal body 302 in the hole formed in bone 372, even extruding a little of the bottom portion of the tube into the bone cavity, assisting in the formation of the seal (Fig. 9C). The tool 301 can then be uncoupled from the connector 300 (while holding body 302 and/or collar 304 against rotation if desired), the drill bit 364 removed and a fluid supply tube 376 connected using a female Luer coupling 378 attached to the tube (Fig. 9D).

When infusion is complete, tube 376 is removed or cut and sealed, tool 301 is re-attached to the male Luer connector 308 on body 302, catches 320 holding collar 304 are then operated to release detents 322 from teeth 312 and body

302 is depressed to stretch tube 306 and free body 302 from the hole in the bone 372. After the body 302 has been depressed and the_collar 304 has been retained on upper tooth 310, tool 301 is pulled - with or without rotation - to remove connector 300 from bone 372.

The sixth and final example of a connector for use in intraosseous infusion illustrates expansion of the sealing means by the use of an internal sleeve. Two variants of this example are shown, one in Figures 1.0A and 10B and the other in Figures 10C and 10D. Steps in the deployment of either form of the device are shown in Figures 11 A - 11 F.

Connector 400 of the first variant of the sixth example comprises a tubular body 402 and a hollow open-ended sleeve 404 adapted to be a sliding fit in body 402. Sleeve 404 has an upper outwardly projecting rim 406 and a pair of opposed slots 407 just below the rim. The bottom or distal extremity of sleeve 404 is preferably rounded or tapered, as shown at 408.

Body 402 has an upper or proximal end that is formed as the male part 410 of a Luer coupling, the upper rim of body 402 being recessed at 411 to take rim 406 of sleeve 404. Disposed below part 410 is an external collar 412 and below collar 412 is a thin-walled, deformable tapered bottom part 414 of bellows like form. The entire body 402 is preferably formed as a unitary injection moulding from resiliently deformable plastic material such as bio-compatible nylon. In this example, bellows-like part 414 serves as the sealing means, which has a diameter, at least in the more distal portion, that is substantially less than the diameter of the hole in the bone (not shown) in which it is intended to fit.

The second variant of the sixth example differs from the first in that the sealing means is attached to a basic moulding as a separate element. The connector 500 of the second variant has a body moulding 502 that is also an open-ended tube having an integral external collar 504. Upper portion 506 of tubular moulding 502 is also formed as the male element of a Luer coupling and also has an internal peripheral recess 507 formed in its upper rim. While the lower portion 508 of moulding 502 is also frustroconical in shape, it is not of concertina form. Instead, it is split by four slots 510 into four flexible fingers 512. An open- ended bellows-like boot 514 of elastomeric material is fitted over lower portion

508, but not attached thereto (eg, by over-moulding, heat-sealing or the use of adhesive). The top of boot 514 has a radial flange 516 adapted to sit adjacent the bottom face of collar 504. Preferably, flange 516 is heat-sealed, glued or otherwise firmly attached to the under side of collar 504. Again, the diameters of bellows like boot 514 and lower part 508 are less than the hole in which they are intended to fit.

Like the first variant of this example, body 502 is intended to be used with a sleeve (which forms part of the connector 500). Since this sleeve is identical to that shown in Figure 10A, the same reference numerals will be used.

Figures 11 A - 11 F show various stages in the deployment of the connectors of the sixth example. These stages will be described with reference to connector 500, but are equally applicable to connector 400. Connector 500 is supplied in a sterile pack with a simple rod-like tool 560, which has a female Luer socket 562 on one end and a pair of opposing clips 565 on the other end, clips 565 being retractable by finger pressure on a button 564. As supplied, the connector body 502 is coupled by its male Luer fitting 506 to one end of tool 560 by female Luer socket 562 and sleeve 404 is attached to the other end of tool 560 by clips 565, which engage sleeve side slots 407. After the infusion site has been prepared by exposing the selected bone 570, drilling a hole 572 and retracting the skin and subcutaneous tissue 574, the tapered bellows-like part 514 of connector 500 is inserted into the hole 572 (Fig. 11 A).

Holding connector body 502 in place by pushing with the fingers of one hand on collar 504, the Luer coupling between tool 560 and connector body 502 is undone. Keeping the fingers in place on collar 504, tool 560 is turned over in the other hand to present the sleeve 404 to connector body 502, and sleeve 404 is inserted into the bore of connector body 502 (Fig. 11 B). Sleeve 404 is then forced into connector body 502 to fully expand its fingers 508 and boot 514 against the sides of hole 572. Button 564 is then pressed to release clips 565 and tool 560 is removed from the assembled connector 500 (Fig. 11C). Sleeve 404 may be supplied suitably lubricated to facilitate its insertion into body 502.

An infusion tube 580 is then coupled to connector 500 with a female Luer coupling 582 and infusion is commenced (Fig. 11 D). After infusion has been completed, female Luer coupling 582 and tube 580 are uncoupled from connector 500, tool 560 is re-clipped to sleeve 404 and used to extract the sleeve from body 502 (Fig. 11 F).

While a number of examples have been described which fulfil the objectives of the invention, it will be appreciated that many others are possible, and that many variants of the examples are possible, without departing from the scope of the invention as defined in the following claims.

Claims

1 A method intraosseous infusion wherein the infusate is a biologically active gas.

2 A method for the in vivo oxygenation of blood in a human or animal patient characterised by the- step of infusing a gas containing reactive oxygen into the interior of a bone of the patient.

3 A method according to claim 1 or claim 2 including the step of forming a hole in the bone into an internal cavity of the bone, fitting a tubular connector into the hole so as to effect a substantially fluid-tight seal with the bone and introducing said gas via said connector.

4 A method according to claim 3 wherein said connector has sealing means for effecting a substantially fluid-tight seal with the wall of the hole, and wherein the method includes the step of actuating said sealing means to effect said seal after insertion of the connector, or portion thereof, into the hole in the bone.

5 A method according to claim 3 or 4 including the steps of: introducing a liquid infusate via said connector in alternation with said gas, and separately regulating the flow of said gas and said liquid infusate to the connector.

6 A method according to claim 3 or 4 including the steps of: introducing a liquid infusate via said connector simultaneously with said gas, and separately regulating the flow of said gas and said liquid infusate to the connector.

7 A method for the intraosseous infusion of a liquid or gaseous infusate into an animal or human patient including the steps of: forming a hole in a bone of the patient to access an internal cavity of the bone, fitting a tubular connector into the hole, said connector being adapted to convey said infusate into the bone, and including the step of actuating sealing means forming part of the connector so as to effect a substantially fluid-tight seal with the bone after insertion of the connector or portion thereof into the hole.

8 A method according to claim 4 or 7 wherein the sealing means comprises a deformable elastomeric material and wherein said sealing means is actuated by compressing said sealing means in the axial, or the radial direction, with respect to the hole so as to press said elastomeric material against the bone to effect said seal.

9 A method according to claim 8 wherein the sealing means comprises a tube of elastomeric material surrounding at least portion of said connector so as to be adapted to contact the bone defining the hole, and wherein the method includes the steps: of stretching said elastomeric tube in the axial direction during the insertion of the connector in to the hole, and allowing the said elastomeric tube to relax and compress in the axial direction and thereby to deform or expand in the radial direction to form said seal.

10 A method according to claim 8 wherein the connector includes an insertable sleeve and wherein the sealing means comprises a ring of elastomeric material adapted to contact the bone defining the hole to form said seal upon actuation, and wherein the actuation of the sealing means includes the steps: of inserting said sleeve into said ring to effect expansion of the ring in the axial direction so as to force said ring into contact with the bone defining the hole. 11 A method according to claim 4 or 7 wherein the sealing means comprises at least one helical fin extending from the surface of the connector, the method including the steps of: pushing the connector axially into the hole to elastically deform the fin against the bone defining the hole so to thereby actuate the sealing means, and, following infusion of the infusate, rotating the connector in an unscrewing direction as determined by the helix of the fin to assist in the removal of the connector from the hole.

12 A method according to claim 4 or 7 wherein the connector has a distal end adapted to protrude into the cavity of the bone when the connector is in place, and wherein the sealing means includes a deformable distal and outwardly extending radial fin, the method including the step of: inserting the connector into the hole so as to elastically deform the fin against the bone defining the hole so as to thereby actuate the sealing means.

13 A method according to claim 4 or 7 wherein the connector has a distal end adapted to protrude into the cavity of the bone when the connector is in place, and wherein the sealing means includes a deformable distal and outwardly extending radial fin, the method including the steps of: inserting the connector into the hole so as to elastically deform the fin against the bone defining the hole, further inserting the connector into the hole so that the fin enters the cavity of the bone and unfolds so as to thereby actuate the sealing means.

14 A method according to any one of claims 3 - 13 wherein the connector includes a cutter on its distal end and wherein the method includes the step of rotating the connector against the bone so as to cause said cutter to form the hole in the bone.

15 A method according to any one of claims 2 to 14 including the step of monitoring arterial blood oxygen saturation and regulating the flow of intraosseous gas to the bone. 16 A method according to any preceding claim including the steps of monitoring for the presence of a gas bubble within a vein or a chamber of the heart, and terminating or reducing the flow of intraosseous gas upon the detection of a bubble.

17 A tubular connector for use in the intraosseous infusion of a liquid or gas under pressure via a hole in a bone, wherein the connector has: sealing means comprising an external surface formed from deformable elastomeric material that is adapted to conform to the surface of the hole and facilitate the formation of a fluid-tight seal between the connector and said surface, and an bore through which fluid may be conveyed into the bone.

18 A tubular connector according to claim 17 including actuating means adapted to actuate said sealing means by compressing said sealing means in the axial, or the radial direction, with respect to the hole so as to press said elastomeric material against the bone to effect said seal.

19 A connector according to claim 18 wherein: said sealing means comprises a tube of elastomeric material adapted to contact the bone defining the hole, and said actuating means includes a part that is movable to stretch said tube in the axial direction during the insertion of the connector in to the hole, and movable to relax the tube after insertion of the connector so as to allow said tube to compress in the axial direction and thereby to deform or expand in the radial direction to form said seal.

20 A connector according to claim 18 wherein: said sealing means comprises a ring of elastomeric material adapted to contact the bone defining the hole to form said seal, and said actuating means includes a sleeve insertable within said ring to effect expansion of the ring in the axial direction so as to force said ring into contact with the bone defining the hole.

21 A connector according to claim 17 wherein: said sealing means comprises at least one deformable helical fin extending from the surface of the connector so as to be adapted to contact the bone defining the hole to form said seal when the connector is entered into the hole, and said helical fin is adapted to assist extraction of the connector from the hole in the bone when the connector is rotated in an unscrewing direction as determined by the helix of the fin.

22 A connector according to claim 17 wherein: said sealing means comprises at least one deformable radial fin extending from the surface of the connector so as to be adapted to contact the bone defining the hole to form said seal when the connector is entered into the hole.

23 A connector according to claim 17 wherein: the connector has a distal end adapted to protrude through the hole into the bone when the connector is in place, and said sealing means includes a deformable radially extending fin on said distal end, said fin being adapted to elastically deform against the bone defining the hole during insertion of the connector into the hole and to unfold upon protrusion of the distal end through the hole so as to thereby be actuated to form said seal.

24 A connector according to claim 17 wherein: the connector includes an insertable sleeve the sealing means comprises a ring of elastomeric material adapted to contact the bone defining the hole to form said seal upon actuation, and actuation of the sealing is effected by insertion of said sleeve to effect the expansion of the ring in the axial direction so as to force said ring into contact with the bone defining the hole.

25 A connector according to claim 17 comprising: a tube adapted to convey gas or liquid, the tube having a distal end, a proximal end and a lumen defining said bore, cutting means on the distal end thereof adapted to cut the hole in the bone upon rotation of the tube, and at least one ring of elastomeric material encircling the tube, said ring comprising said sealing means.

26 Apparatus for blood oxygenation in a human or animal patient comprising: a source of gas containing biologically active oxygen, a connector adapted to be inserted in a substantially fluid-tight manner into a hole in a wall of a bone of the patient so as to provide fluid access to a cavity of the bone, regulator means for regulating the flow of said gas from said source, and tube means adapted to convey the gas from said regulator to said connector, whereby gas can be introduced into said cavity.

27 Apparatus according to claim 26 including: monitoring means for monitoring a physiological parameter indicative of blood oxygenation, connection means adapted to connect said monitoring means to the regulator whereby the flow of gas into the bone can be adjusted inversely with respect to the level of blood oxygenation indicated by the monitoring means.

28 Apparatus according to claim 27 wherein: said monitoring means is adapted to monitor the oxygen saturation of arterial blood.

29 Apparatus according to claim 27 wherein: said monitoring means is adapted to monitor peripheral perfusion by optical means as a proxy for blood oxygenation.

30 Apparatus according to any one of claims 27 to 29 including: detector means for detecting the presence of gas bubbles within the vascular system of the patient, signal means adapted to connect said detector means to the regulator whereby the flow of gas into the bone can be reduced or stopped upon receipt of a signal from said signal means indicative of the detection of one or more gas bubbles.

31 Apparatus according to any one of claims 27 to 29 including: detector means for detecting the presence of gas bubbles within a chamber of the heart of the patient, signal means adapted to connect said detector means to the regulator whereby the flow of gas into the bone can be reduced or stopped upon receipt of a signal from said signal means indicative of the detection of one or more gas bubbles.