Technical Field

The present disclosure relates to apparatus, systems and methods for fluid delivery, specifically to controlling the delivery of an injection fluid to a target site.

Background

Regional anaesthesia is a procedure that provides the loss of sensation to a specific area of the body by disrupting the transmission of signals along nerves. The local anaesthetic is administered through injection and the solution surrounds the nerve plexus inhibiting sodium ion conductance, stopping the transmission of noxious stimuli.

Regional anaesthesia has become more popular due to its advantages over general anaesthesia, for example the ability to keep the patient conscious during the procedure, allowing them to maintain control of their respiratory system reducing associated risks. Regional anaesthesia can also be used as a regional block in conjunction with light general anaesthesia. It also provides other benefits such as post-operative analgesia which allows for a smoother recovery, faster discharges from hospital and reduction of nausea. These benefits have increased the use of regional anaesthesia; however this has also highlighted the complications surrounding the area.

Problems associated with regional anaesthesia include intravenous injection, toxic reaction, and nerve damage. For example, toxic reaction may occur when the total concentration of an anaesthetic delivered is too high or it is not administered to the correct site. Intravenous injection may cause a toxic reaction and may cause the anaesthetic to spread throughout the body instead of providing a localised dose to the area of interest, with potentially life threatening consequences. Damage to nerves can be caused by direct needle trauma or by excessive injection pressures .

Location of the nerve plexus for injection of an anaesthetic can be performed using a nerve stimulation technique or an ultrasound guided technique. When using the ultrasound guided technique the anaesthetist usually has one hand directing the needle and the other hand controlling the ultrasound probe. This means that anaesthetists require an additional practitioner to compress the syringe plunger. As this practitioner may not be medically trained in the field of regional anaesthesia, they may be unaware of the risks associated with high injection pressure.

Summary

Aspects and examples of the present disclosure aim to address at least a part of the above described technical problems and/or related problems. Aspects of the invention are as set out in the independent claims and optional features are set out in the dependent claims.

In one aspect there is provided a fluid delivery system, for example this may be a system for injecting medical compositions into a human or animal body, e.g via a fluid delivery lumen such as a hypodermic needle. The system comprises a syringe and a valve; wherein the syringe comprises an aspiration barrel and an injection barrel; and the valve is configured to control fluid flow between the syringe and a fluid delivery lumen for aspiration and injection of a target site; wherein the valve is operable in a reverse and forward position, such that in the reverse position the valve is configured to enable fluid to flow from the fluid delivery lumen to the aspiration barrel; and in the forward position the valve is configured to enable fluid to flow from the injection barrel to the fluid delivery lumen.

In one aspect there is provided a fluid delivery system, for example this may be a system for injecting medical compositions into a human or animal body, e.g via a fluid delivery lumen such as a hypodermic needle. The system comprises a syringe comprising an aspiration barrel and an injection barrel; and a valve comprising a fluid delivery lumen connector, the valve arranged to enable fluid flow in a first configuration and a second configuration; wherein in the first configuration the valve is configured to enable fluid flow from the fluid delivery lumen connector to the aspiration barrel; and in the second configuration the valve is configured to enable fluid flow from the injection barrel to the fluid delivery lumen connector.

In one aspect there is provided a syringe for providing a fluid to a fluid delivery lumen for injection at a target site, e.g. for injecting medical compositions into a human or animal body, e.g via a fluid delivery lumen such as a hypodermic needle. The syringe comprises a barrel; a plunger configured to move slidably within the barrel for expelling fluid from the barrel; and a biasing means configured to pressurise fluid in the barrel to provide an injection pressure, wherein the injection pressure does not exceed 30 psi, for example does not exceed 20 psi, for example does not exceed 15 psi, for example does not exceed 10 psi ..

In one aspect there is provided a syringe for providing a fluid to a fluid delivery lumen for injection at a target site, the syringe comprising an aspiration barrel, and an aspiration plunger in said barrel for drawing fluid from the fluid delivery lumen, the aspiration barrel comprising a lock for locking said plunger in a position which provides reduced fluid pressure in the aspiration barrel; and an injection barrel, comprising a fluid reservoir for holding an injection fluid and for providing said fluid to the fluid delivery lumen.

The systems and syringes described herein may be handheld.

In one aspect there is provided a method of operating a fluid delivery system, the system comprising a syringe and a fluid delivery lumen, wherein the syringe comprises an aspiration barrel configured to obtain fluid from the fluid delivery lumen and an injection barrel configured to provide an injection fluid to the fluid delivery lumen; and wherein the method comprises providing a negative pressure in the aspiration barrel; releasing a biasing means to pressurise fluid in the injection barrel; inserting the fluid delivery lumen at a target site. This method may be used for injecting a medical composition, such as an anaesthetic, into a target site in a human or animal body.

Each of these foregoing aspects may be further refined as set out in the examples described herein.

The valve may be have a neutral position, wherein in the neutral position the valve prevents fluid flow between the syringe and the fluid delivery lumen. In the neutral position the valve may also prevent fluid flow between the aspiration barrel and the injection barrel.

The valve may be operable to transition between the reverse position and the forward position. The valve may be configured so that transitioning between the reverse position and the forward position requires the valve to change from the reverse position, into the neutral position, and then from the neutral position into the forward position. This may provide improved control of the system during a one-handed injection procedure and may help to ensure that there is no cross-contamination of fluid between the aspiration barrel and the injection barrel. The syringe may further comprise a biasing means to pressurise fluid in the injection barrel. The biasing means may be provided by a spring. This may enable fluid to be automatically injected at a given pressure to the target site. The syringe may comprise a restraint. The biasing means may be arranged so that, when the second plunger is withdrawn to pull fluid into the injection barrel, the biasing means is primed (e.g. by compressing a spring) . The restraint can then be engaged to hold the plunger in position. Such a restraint may be provided by closing the valve to prevent fluid from flowing out from the injection barrel. It may also be provided by a locking mechanism which locks the position of the plunger relative to the injection barrel. Release of the restraint may thus apply a pre-determined fluid pressure at the fluid delivery lumen. The biasing means may be configured to provide an injection fluid pressure that does not exceed 30 psi, for example does not exceed 20 psi, for example does not exceed 15 psi, for example does not exceed 10 psi. This may reduce the possibility of nerve damage at the target site caused by to high injection pressure.

The injection pressure may be provided at a tip of the fluid delivery lumen. The injection pressure may also be provided in the delivery system, for example at the syringe, for example at the second plunger.

The syringe may further comprise a first plunger configured to move slidably within the aspiration barrel; and a second plunger configured to move slidably within the injection barrel. To pressurise the fluid in the injection barrel, the biasing means may be configured to exert a force on the plunger.

The biasing means may comprise a resilient member, such as a spring. The resilient member may be mounted on the second plunger .

The valve may comprise a mechanical slider operable by hand to move the valve between the reverse, neutral and forward positions. This may enable a practitioner to switch the valve between positions in a single movement using a single hand for example by a single digit such as a thumb or finger. The valve may comprise a switch, rocker, button, trigger or other mechanism that enables the valve to be switched by hand between different states .

The aspiration barrel may be configured to provide a volume of fluid at reduced pressure (e.g. lower than ambient pressure), such as vacuum, for connection to the fluid delivery lumen via the valve. This reduced pressure may be provided by withdrawing a plunger in the aspiration barrel and holding it in a withdrawn position, e.g. using a locking mechanism as described elsewhere herein. Irrespective of how it is provided, this may enable the aspiration barrel to aspirate fluid from a target site via the fluid delivery lumen - e.g. to obtain, or to test whther it is possible to obtain, aspirated fluid from the target site. The injection barrel may be configured to hold an injection fluid for delivering to the target site , e.g. by injection.

The aspiration barrel and the injection barrel may be affixed to one another, for example where they are laterally affixed, for example side-by-side. This may reduce the number of parts for manufacturing, and may allow both aspirating and injecting functions to be performed by a single component that can be held in a single hand. The syringe may comprise a first locking mechanism configured to engage with the first plunger, to inhibit movement of the first plunger relative to the aspiration barrel. This may enable one handed operation of the system during regional block.

The first plunger may be operable to rotate to interlock with the first locking mechanism, to inhibit movement of the first plunger relative to the aspiration barrel. This may further assist one handed operation by enabling straightforward locking of the plunger by hand.

The syringe may comprise a second locking mechanism configured to engage with the second plunger, to inhibit movement of the second plunger relative to the injection barrel. This may further assist one handed operation by allowing the biasing means to be held in one hand in a loaded, for example compressed, state until it is desirable to release it. The second plunger may be operable to rotate to interlock with the second locking mechanism, to inhibit movement of the second plunger relative to the injection barrel. This may enable the plunger to be locked by a single hand. The second plunger may be further configured to disengage with the second locking mechanism upon rotation, to pressurise the fluid in the injection barrel. This may enable automatic pressurising of injection fluid through a simple hand movement. This automatic pressurising may also enable automatic injection of an injection fluid through a simple operation of a switching component .

The first and second locking mechanisms may be provided by a single component part. This may assist one handed operation and may minimise the parts necessary for manufacturing and construction of the syringe.

The syringe may further comprise a second biasing means for providing negative pressure in the aspiration barrel. In some examples the biasing means is provided by a spring. The second biasing means may enable negative pressure, for drawing fluid towards the aspiration barrel, to be provided automatically in the aspiration barrel. The biasing means may enable the amount of negative pressure remaining in the aspiration barrel to be visibly shown, for example based on the position of the plunger as a spring is returned to its un-sprung position.

A method of operating the fluid delivery system may also be provided, wherein the method comprises switching the valve from the reverse position to the forward position via the neutral position .

The valve may be operable to be switched by hand between the first configuration and the second configuration. This may minimise the number of people required to operate the system.

The fluid delivery lumen may be a needle, for example for injection and aspiration of fluid from a target site. The system may comprise the needle.

The injection pressure may be provided at a tip of the fluid delivery lumen. The injection pressure may also be provided in the delivery system, for example in the injection barrel, for example at the second plunger.

The biasing means may be mounted on the plunger. The syringe may comprise a biasing means, such as a resilient member for example a spring, for pressurising the injection fluid. This may enable fluid to be automatically injected at a specific pressure or flow rate to the target site.

The system may further comprise a valve configured to control fluid flow between the syringe and the fluid delivery lumen.

The method may further comprise switching the valve to a reverse position to enable fluid to flow between the fluid delivery lumen and the aspiration barrel.

The valve may be configured to prevent fluid flow between the injection barrel and the fluid delivery lumen in the reverse position. This may prevent cross-contamination of injection fluid and aspirated fluid in the fluid delivery lumen.

The method may further comprise switching the valve to a forward position to enable a fluid flow between the injection barrel and the fluid delivery lumen.

The valve may be configured to prevent fluid flow between the fluid delivery lumen and the aspiration barrel in the forward position. This may prevent cross-contamination of injection fluid and aspirated fluid in the fluid delivery lumen.

Switching the valve to a forward position may comprise switching the valve to a neutral position in which fluid flow between the fluid delivery lumen, the aspiration barrel and the injection barrel is prevented. This may ensure that there is no cross contamination of fluid between the aspiration barrel and the injection barrel when switching to the forward position.

The syringe may further comprise a plunger configured to move slidably within the injection barrel.

The biasing means may be configured to drive the plunger. Releasing the biasing means to inject the injection fluid to the target site may comprise providing an injection pressure that does not exceed a certain pressure, for example 30 psi, for example does not exceed 20 psi, for example does not exceed 15 psi, for example does not exceed 10 psi at the target site. This may reduce the possibility of nerve damage at the target site caused by to high injection pressure.

The method may further comprise loading the biasing means. Loading the biasing means may comprise retracting the plunger along the injection barrel.

Loading the biasing means may further comprise interlocking the plunger with a locking mechanism. This may also allow the biasing means to be held in a compressed or loaded state until it is desirable to release it.

The system may be an anaesthesia delivery system. The syringe may be arranged to hold anaesthetic fluid.

The delivery lumen may comprise a needle. The needle may couple to the syringe, for example to a syringe holding anaesthetic fluid. A controller may be configured to perform any of the methods described herein.

Aspects of the invention may be provided in conjunction with each other and features of one aspect may be applied to other aspects. Brief Description of Drawings

Embodiments of the disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which :

Figures 1A-C illustrate an example fluid delivery system;

Figures 2A shows a side view of an example syringe;

Figure 2B shows a cross sectional view of an example syringe;

Figure 2C shows an end view of an example syringe;

Figures 3A-D show an example flow control valve;

Figure 4 shows an example syringe.

Figure 5 is a flow diagram illustrating an example method;

Speci fic Description

Described herein with reference to the Figures are systems, apparatus and methods relating to the delivery of a fluid, such as an anaesthetic, to a target site. Such a fluid delivery system may integrate aspiration and injection functions, thus enabling the practitioner to exert greater control over the process. The system may also allow for the pressure at which a fluid is injected to be controlled or limited, which may reduce the possibility nerve damage as a result of injection. The system comprises a syringe with two barrels, one for storing fluid to inject at target site, and the other to receive any fluid aspirated from the target site. The system also comprises a valve which can switch between an aspiration state, in which fluid can be drawn from the target site towards the aspiration barrel, and an injection state in which fluid held in the injection barrel can be delivered to the target site. In this way, both the aspirating and injecting functions may be provided using a single syringe . Figures 1A-C show an example fluid delivery system 100. Figure 1A shows a system 100 comprising a syringe 110 coupled to a valve 120 via first and second connection tubes 141, 142. The system also comprises a fluid delivery lumen such as a needle 130. The needle 130 is coupled to the valve 120 to enable fluid to flow between the needle 130 and the syringe 110 via the connection tubes 141 , 142.

The apparatus is shown in more detail in Figures IB and 1C. The syringe 110 comprises an aspiration barrel 104 and an injection barrel 105. The aspiration barrel 104 is configured to obtain fluid from the needle 130 via the first connection tube 141. The injection barrel 105 is configured to store an injection fluid for delivery to a target site, and to provide this fluid to the needle 130 via the second connection tube 142.

The walls of the connection tubes 141, 142 and the aspiration barrel 104 may be transparent, for example they may comprise a transparent material such as a clear plastic, so that during operation a practitioner can identify any fluid, e.g. blood, that may be aspirated from the target site and drawn towards the aspiration barrel. For example, in operation fluid aspirated from the target site flows into the first connection tube 141 where it can be seen by a practitioner. The injection barrel 105 may also be transparent.

The aspiration barrel 104 and the injection barrel 105 are affixed to one another along their side, and are the same length such that the opposing ends of the aspiration barrel 104 and the injection barrel 105 are aligned. Therefore, an outlet of the aspiration barrel 104 and an outlet of the injection barrel 105 are aligned in the plane perpendicular to the lengths of the barrels 104, 105. The valve 120 comprises an aspiration outlet 121 arranged to coupling to the first connection tube 141 for example for providing fluid to the aspiration barrel 104. The valve 120 also comprises an injection inlet 122 arranged for coupling to the second connection tube 142 for example for obtaining fluid from the injection barrel 105. The valve 120 further comprises a fluid delivery lumen connector 123 arranged to couple to a fluid delivery lumen such as the needle 130. The fluid delivery lumen connector 123 is configured to provide fluid to and obtain fluid from a target site via a fluid delivery lumen e.g. the needle 130. The valve 120 is configured to switch the system between an aspiration configuration and an injection configuration. In the aspiration configuration the valve 120 provides a flow path between the needle 130 and the aspiration barrel 104 via the valve 120 and connection tube 141. In the injection position, the valve 120 provides a flow path between the injection barrel 105 and the needle 130 via connection tube 142. Valve structure and operation is described further with reference to Figures 3A-E. The syringe further comprises a first plunger 106 and a second plunger 107. The first plunger is configured to move slidably within the aspiration barrel 104 and the second plunger 107 is configured to move slidably within the injection barrel 105. Each of the plungers 106, 107 can be retracted to provide a negative pressure in their respective barrels 104, 105. The plungers 106, 107 are also operable to pressurise fluid contained in the barrels 104, 105, for example to expel fluid contained in the barrels 104, 105. For example in the example shown in Figures 1B-

C the plungers 106, 107 are operable to move slidably towards an outlet of their respective barrels 104, 105 to expel fluid contained in the barrels 104, 105.

The syringe 110 further comprises a biasing means 109 such as a spring for pressurising fluid in the injection barrel 105. In the example shown in Figures 1B-C, the biasing means 109 is configured to drive the second plunger 107, and in this example the biasing means 109 is mounted on the second plunger 107 to drive it. In operation, the second plunger 107 can be retracted and, upon release, automatically pressurise fluid in the injection barrel 105 due to the force exerted on the second plunger 107 by the biasing means 109. Without wanting to be bound by theory, the spring constant of the biasing means 109 can be selected so that a particular injection pressure is provided, for example at the tip of the needle 130, using Hooke's Law:

F = kx

In which F is the force exerted by the biasing means, k is the spring constant, and x is the extension of the spring. A spring constant can thus be selected based on a maximum desired pressure :

PA

k =—

x

in which P is the pressure, A is the cross-sectional area of the flow path.

Therefore, a spring constant of the biasing means 109 can be selected based on the dimensions of the syringe 110 and/or of the biasing means 109 itself, so that a desired or maximum injection pressure of the fluid is not exceeded, e.g. 30 psi, 20 psi, 15 psi, 10 psi.

High injection pressures may lead to an increased risk of nerve damage, and as such it may be desirable to limit the injection pressure by using a particular spring constant. In some examples the biasing means may be configured so that the injection pressure at a tip of the fluid delivery lumen does not exceed 30 psi, 20 psi, 15 psi, or 10 psi.

Figure IB shows the second plunger 107 fully retracted and in a charged state. Figure 1C shows the biasing means 109 in a fully discharged state, in which the biasing means 109 is fully extended. Therefore in this example the full extension (x) of the biasing means 109 is given by the distance that the biasing means 109 extends between these two states in the injection barrel 105. By selecting the spring constant of the biasing means fluid can be injected automatically upon release of the second plunger 107, and the injection pressure of this fluid can be limited, e.g. to 30 psi, 20 psi, 15 psi, 10 psi .

It is noted that although Figure IB shows both the first 106 and second 107 plungers fully retracted, and Figure 1C shows both plungers 106, 107 as fully compressed, it is of course the case that each plunger 106, 107 can move slidably within their respective barrel 104, 105 completely independently of one another .

The syringe 110 further comprises a first and second locking mechanism, both provided by element 108 in Figures 1B-C. first plunger 106 and second plunger 107 are operable to engage and disengage with the first and second locking mechanisms respectively, when in a fully retracted state. This is described in more detail below with reference to Figure 2A-B Outlets of the aspiration barrel 104 and injection barrel 105 are coupled to the connection tubes 141, 142 via a connector 150. The connector is configured so that the aspiration connection tube cannot couple to the outlet of the injection barrel 105, and the injection connection tube cannot couple to the outlet of the aspiration barrel 104. The connector 150 comprises two reverse Luer tapers and a mechanical failsafe, for example in the form of a protrusion on the injector side, to prevent the connector 150 from coupling to the outlets of the syringe 110 in the incorrect configuration. The connector 150 is arranged so that the syringe 110 is incompatible with (e.g. cannot form a connection with) a standard Luer device. The connector 150 is also configured so that the connection tubes 141, 142 are incompatible with (e.g. cannot form a connection with) a standard syringe. The aspiration barrel 104 and the injection barrel 105 are affixed to one another, in particular they are laterally affixed side-by-side. In the example shown, the aspiration barrel 104 and injection barrel 105 are rigidly fixed to each other, however in other examples they may be flexibly fixed to one another. In other examples the aspiration barrel and the injection barrel may be provided by separate elements. These elements may be configured to attach and detach from one another. In such examples, the aspiration and injection barrels may perform the functions and methods described herein in either attached or detached configurations.

Figures 2A-C show an example double-barrelled syringe 200. Specifically, Figure 2A gives a side view of the syringe 200, Figure 2B gives a cross-sectional side view of the syringe 200 and Figure 2C gives a cross-sectional end view of the syringe

200. The syringe 200 comprises an aspiration barrel 204 and an injection barrel 205, and further comprises a first plunger 210 configured to move slidably within the aspiration barrel 204, and a second plunger 220 configured to move slidably within the injection barrel 205. The syringe 200 further comprises a biasing means 209 for driving the second plunger 220 to pressurise fluid in the injection barrel 205. In the example shown in Figure 2B the biasing means is a spring and is mounted on the second plunger 220.

The syringe 200 also comprises a locking member 208 that provides a first locking mechanism 230 that is configured to interlock with the first plunger 210, and a second locking mechanism 240 configured to interlock with the second plunger 220. By forming an interlock, the first 230 and second 240 locking mechanisms are configured to inhibit movement of the first 210 and second 220 plunger respectively. The first plunger 210 comprises a plurality of radially spaced protrusions 212, for example four protrusions spaced equally around the plunger, such that the first plunger 210 has a cross shaped cross-section. The first locking mechanism 230 comprises a cross-shaped opening that enables the first plunger to move slidably along the aspiration barrel 204 but that inhibits lateral movement or rotation of the first plunger 210. The first plunger 210 also comprises a series of notches 211, such that at the point at which the notches 211 are aligned with the first locking mechanism 230, the first plunger 210 is operable to freely rotate, such that the protrusions 212 come in and out of alignment with the first locking mechanism 240 upon rotation. The first plunger 210 can thereby interlock with the first locking mechanism 230 as the protrusions 212 are not able to advance through the first locking mechanism 230. As such, the first locking mechanism 230 is configured to inhibit movement of the first plunger 210 relative to the aspiration barrel 204.

Similarly, the second plunger 220 also comprises protrusions 222 and notches 221, and is configured to interlock with the second locking mechanism 240 in substantially the same way as described above with reference to the first plunger 210, to inhibit movement of the second plunger 220 relative to the injection barrel 205. Also shown is a connector 250 configured to couple to the aspiration barrel 204 and the injection barrel 205, and to enable fluid to flow between at least one of the barrels 204, 205 and a fluid delivery lumen, such as a connection tube, needle or catheter . In an example operation, with both plungers 210, 220 fully discharged, the syringe 200 may be coupled (via connector 250) to a needle which can be inserted at a fluid source such as an anaesthetic source. The second plunger 220 is retracted to provide a negative pressure in the injection barrel 205, enabling a fluid such as an anaesthetic to be drawn into the injection barrel 205. As the second plunger 220 is retracted, the biasing means 209 to be loaded into a charged state, for example by compressing a spring. Once the second plunger 220 is retracted to the point at which the notches 221 engage with the second locking mechanism 240, the second plunger 220 may be rotated so that movement of the second plunger 220 along the injection barrel 205 is inhibited.

The syringe 200 may then be connected at connector 250 to first and second connection tubes to form a flow path to and from a fluid delivery lumen via a valve. In this way a flow path may be provided between a target site and each of the aspiration barrel 204 and the injection barrel 205, via the valve. This target site may be a candidate site on a body at which to inject the anaesthetic fluid contained in the injection barrel 205. Prior to the insertion of the fluid delivery lumen to the target site the second plunger 220 is disengaged from the second locking mechanism 240, e.g. by rotating it. Upon disengagement the biasing means 221 automatically drives the second plunger 220, pressurising the fluid contained in the injection chamber 205, and priming the connection tube to remove any air contained therein. Once the fluid delivery lumen is inserted at the target site, the first plunger 210 is retracted to provide a negative pressure in the aspiration barrel 204, and locked into place as described above. The valve is switched to a reverse position causing any fluid present at the tip of the fluid delivery lumen to be aspirated and drawn towards the aspiration barrel 204. Based on what fluid, if any, has been drawn towards the aspiration barrel 204, a practitioner can determine whether the target site is a suitable site for injection of the fluid contained in the injection barrel 205. For example, if blood can be seen to have been drawn into the aspiration barrel 204 a practitioner may determine that the target site is within a blood vessel and therefore is not a suitable site for the injection of an anaesthetic fluid. In this case the fluid delivery lumen can be removed and another site chosen.

If the practitioner determines that the site is suitable, then they may switch the valve into a forward position such that the pressurised fluid is provided to the fluid delivery lumen for injection at the target site.

The above process may be further controlled using a valve, for example the valve 120 shown in Figure 1. Examples of valves operable to control the aspiration and injection process are described in more detail below with reference to Figures 3A-E.

Figures 3A-C give exterior views of an example valve 300 which may be used to control the aspiration and injection of a target site. For example, such a valve may be used in conjunction with the syringe described with reference to Figure 2 and/or as part of the system described with reference to Figure 1. The valve 300 is arranged so that it can be held and operated by a single hand. The valve 300 comprises an outer casing 310 which is substantially cuboidal but which has two opposing concave faces which may enable a practitioner to more easily hold the valve 300. Each concave face comprises a plurality of ridges 305 which may further improve the grip of the practitioner.

The valve 300 comprises a fluid delivery lumen connector 301 configured to couple to a fluid delivery lumen, such as a needle. The connector 301 is configured to provide fluid to and obtain fluid from a fluid delivery lumen. The valve 300 comprises an aspiration outlet 302, configured to provide fluid obtained from the fluid delivery lumen to a container, for example to a syringe or to the aspiration barrel of a syringe such as is described above with reference to Figures 1 and 2. The valve 300 also comprises an injection inlet 303, configured to obtain fluid from a container, for example from a syringe or from the injection barrel of a syringe such as is described above with reference to Figures 1 and 2, and provide it to a fluid delivery lumen, e.g. for delivery to a target site.

The valve 300 also comprises a mechanical slider 304 operable by hand, and configured to move slidably within a channel 306.

Figure 3D shows an internal cross sectional view of an example valve 300, e.g. the view along the line A-A shown in Figure 3A. As shown, the mechanical slider 304 is coupled to a piston 320 in order to switch the valve 300 between different flow path configurations. In more detail, the valve can be configured in a reverse position in which a flow path between the aspiration outlet 302 and the fluid delivery lumen connector 301 is provided; a neutral position in which flow is prevented between the delivery lumen connector 301, the aspiration outlet 302 and the injection inlet 303; and a forward position in which a flow path between the fluid delivery lumen connector 301 and the injection inlet 303 is provided. The mechanical slider 304 can be operated to move the piston 320 within a chamber 350 of the valve 300 so as to switch the valve 300 between the reverse, neutral and forward positions. A first opening 307 is provided so as to form a flow path between the aspiration outlet 302 and the fluid delivery lumen connector 301 via the chamber 350. A second opening 308 is provided so as to form a flow path between the injection inlet 303 and the fluid delivery lumen connector 301 via the chamber 350. The piston 320 forms a plurality of seals 315, 325, 335 with the casing 310 to inhibit fluid flow between the injection inlet 303, the aspiration outlet 302 and the fluid delivery lumen connector 301 in the reverse, neutral and forward positions.

Specifically, the piston 320 comprises a first seal 315 with the casing 310 which is arranged to prevent any fluid flow or leakage between the aspiration outlet 302 and the injection inlet 303. Specifically the first seal 315 is arranged to prevent fluid flow between the aspiration outlet 302 and the injection inlet 303 regardless of the position of the piston 320 within the chamber 350. The piston further comprises a second seal 325. As the piston 320 moves slidably within the chamber 350 the second seal 325 is configured to block and unblock the first opening 307, so as to open and close the flow channel between the aspiration outlet 302 and the fluid delivery lumen connector 301. Specifically, when the piston 320 is in an aspiration position (as is shown in Figure 3D) the first opening 307 is uncovered, and when the piston is in a neutral or forward position the first opening is blocked by the second seal 325. The piston further comprises a third seal 335. As the piston 320 moves slidably within the chamber 350 the third seal 335 is configured to block and unblock the second opening 308, so as to open and close the flow channel between the injection inlet 303 and the fluid delivery lumen connector 301. Specifically, when the piston 320 is in an injection position the second opening 309 is uncovered, and when the piston is in a neutral or reverse position (as is shown in Figure 3D) the second opening is blocked by the third seal 335. Figure 3E shows another cross section view of example valve 300. As is shown, the valve 300 can be positioned in neutral, reverse (aspiration) and forward (injection) positions. In the neutral position the position of the second seal 325 and the third seal 335 prevent any fluid flow between the fluid delivery lumen connector 301 and either the aspiration outlet 302 or the injection inlet 303. In the reverse position the piston 320 is positioned such that fluid is able to flow from the fluid delivery connector 301 to the aspiration outlet 302, but the third seal 335 still prevents any fluid flow between the injection inlet 303 and the fluid delivery lumen connector 301. In the forward position the piston 320 is positioned such that fluid is able to flow from the injection inlet 303 to the fluid delivery connector 301, but the second seal 325 prevents any fluid flow between the fluid delivery lumen connector 301 and the aspiration outlet 302.

In operation the valve 300 is operable to transition from the reverse position to the forward position and back again via the neutral position. Therefore to move the valve 300, or a system comprising the valve 300, between an aspiration and injection state, the valve must first be moved into an intermediate neutral state in which all flow paths across the valve are blocked. The piston 320 can be moved slidably between these positions in a single motion, for example by a practitioner operating the mechanical slider 304.

Figure 4 shows an example syringe 400 for injecting a fluid, for example an anaesthetic, to a target site. The syringe comprises a barrel 405 arranged to contain an injection fluid, and a plunger 406 configured to move slidably within the barrel 405. A biasing means 409 is also provided to pressurise the fluid contained in the barrel 405 and thereby to expel the fluid from the syringe 400 at an outlet 410. The outlet 410 is arranged for connection with a fluid delivery lumen, for example a connection tube, needle or catheter.

In the example shown the biasing means 409 is provided by a spring mounted on the plunger 406, and is configured to drive the plunger 406 to pressurise fluid contained in the barrel 405. The biasing means is arranged such that the fluid is automatically pressurised upon release of the plunger 406. As described above with reference to Figure 1, the spring constant of the biasing means 409 can be selected based on the dimensions of the syringe 400 so that a desired or maximum injection pressure of the fluid is not exceeded, e.g. 15psi. This may reduce the possibility of potential nerve damage as a result of injection.

The syringe further comprises a locking mechanism 408, configured to engage with the plunger 406 substantially as described above with reference to Figure 2 to inhibit movement of the plunger 406 relative to the barrel. Specifically the plunger 406 comprises a plurality of protrusions that may be brought in and out of alignment with the locking mechanism 408 upon rotation of the plunger 406 when the plunger 406 is in a freely rotatable retracted state.

Figure 5 is a flow diagram showing an example method that may be performed using a fluid delivery system, for example the fluid delivery systems described above with reference to the preceding Figures. Such a method may be used to ensure that an injection fluid such as an anaesthetic is provided to a desired target site, for example to ensure that the fluid is not injected intravenously. The system comprises a syringe, a valve and a fluid delivery lumen, wherein the syringe comprises an aspiration barrel configured to obtain fluid from the fluid delivery lumen and an injection barrel configured to provide an injection fluid to the fluid delivery lumen, for example as described above with reference to the preceding figures. The injection barrel is pre- loaded with the injection fluid, for example a plunger of the injection barrel is retracted and engaged with a locking mechanism to load a biasing means and draw injection fluid into the injection barrel. The method comprises providing 501 a negative pressure in the aspiration barrel and releasing 502 the biasing means to pressurise fluid in the injection barrel and prime a connection tube connected to the injection barrel to expel any air present in the connection tube. The fluid delivery lumen is inserted 503 at a target site. The valve is switched 504 into a reverse position such that, due to the negative pressure in the aspiration barrel, if blood is present at the target site it is aspirated and provided towards the aspiration barrel, for example so that it is visible in a transparent connection tube connected to the aspiration barrel. If it is determined 505 that blood is present, then the fluid delivery lumen is removed 506. If it is determined 505 that blood is not present, then the valve is switched 507 to inject the injection fluid to the target site.

The system for performing this method may further comprise the valve configured to control fluid flow between the syringe and the fluid delivery lumen. The valve may be switched to a reverse position to enable fluid to flow between the fluid delivery lumen and the aspiration barrel. The valve may be configured to prevent fluid flow between the injection barrel and the aspiration barrel in the reverse position.

The valve may be switched to a forward position to enable a fluid flow between the injection barrel and the fluid delivery lumen, . The valve may also be configured to prevent fluid flow between the fluid delivery lumen and the aspiration barrel in the forward position. Switching the valve to a forward position may comprise switching the valve to a neutral position in which fluid flow between the fluid delivery lumen, the aspiration barrel and the injection barrel is prevented.

Releasing the biasing means to pressurise the injection fluid may comprise providing an injection pressure that does not exceed a certain pressure, e.g. 30 psi 20 psi, 15 psi, 10 psi.

Providing 501 a negative pressure may comprise retracting a plunger of a syringe, and loading the biasing means may comprise retracting a plunger along the injection barrel and may further comprise interlocking the plunger with a locking mechanism. Releasing 502 the biasing means may comprise disengaging the locking mechanism. Engaging and disengaging with the locking mechanism may comprise rotating the plunger, for example when the plunger is in a retracted state.

If it is determined that blood has been aspirated from the target site this may indicate that a tip of the fluid delivery lumen is in a blood vessel and therefore another site for injection should be found. A practitioner can remove the fluid delivery lumen from a target site and move it to another several times, repeating the aspiration steps described until a suitable site is found. The negative pressure provided by the aspiration barrel may enable several aspiration attempts for e.g. a single retraction of the aspiration plunger. The system described may have enough negative pressure for e.g. a ten-second aspiration or e.g five two-second aspirations. If further negative pressure is required, this can be topped up be provided by providing more negative pressure in the aspiration barrel, e.g. by retracting the plunger again. The amount of negative pressure provided by the aspiration barrel will vary, e.g. based on the size of the barrel and how far the plunger is retracted.

Although many of the above embodiments have been described with reference to a single syringe comprising two barrels, in some examples certain functions of the syringe described herein could be performed using two separate syringes, for example a syringe for aspiration and a syringe for injection. Other embodiments for example that include a greater number of barrels or syringes are also envisaged, for example that may enable the delivery of more than one substance of interest to a target site.

Although the above apparatus, systems and methods are described above with reference to a needle it will be understood that other kinds of fluid delivery lumen may be used in conjunction with the apparatus described above, for example a catheter.

While the aspiration barrel and connection tubes have been described above as transparent, other colours and optical properties of the barrels and/or connection tubes are envisaged, for example those that may allow a practitioner to determine the presence of fluid in the aspiration barrel.

Other means for determining the presence of an aspiration fluid are also envisaged, for example through the use of sensors e.g. optical or mass sensors.

Means for measuring the pressure in the system may also be provided, for example for measuring the pressure in the injection barrel and/or the pressure in the aspiration barrel. Such means may be provided by a pressure sensor, for example an electronic pressure sensing circuit. Means for displaying the measured pressure may also be provided, for example a digital or analogue display or monitor configured to display pressure information obtained from the pressure measuring means.

The function of the aspiration barrel may be provided by a vacuum tube, for example a vacuum blood collection device which may be connected to the valve in place of the aspiration barrel by the connection tube.

The aspiration barrel may comprise a biasing means for providing vacuum/negative pressure to draw fluid towards the aspiration barrel . For example a spring may be provided within the aspiration barrel. For example, the biasing means may be arranged between the first plunger and the outlet of the barrel. The biasing means may enable negative pressure to be provided automatically, for example as a compressed spring is released. In some examples the biasing means may provide negative pressure automatically as the first plunger is disengaged from a locking mechanism, for example a compressed spring may be released and expand upon disengagement. The biasing means may enable the amount of vacuum remaining in the aspiration to be visibly shown, for example based on the position of the plunger as a spring is returned to its un-sprung position.

In some examples the aspiration barrel and the injection barrel are detachable from one another. In this example aspirated fluid can be collected in the aspiration fluid which in turn can detach from the delivery system. For example the aspiration barrel could then be transported for pathology analysis of the aspirated fluid. Although the first and second locking elements are described as comprising cross-shaped openings and as being provided by a single element, it will be understood that this is merely exemplary. Other locking mechanisms are envisaged, for example that comprise openings with differently shaped cross-sections or that provide different means for securing the plungers altogether. For example a notch may be provided that is configured to engage with a switch and/or catch element. This may enable the plunger to lock into position without needing to be rotated, thus improving the stability of the system during the locking/unlocking procedure.

The locking mechanisms may alternatively be provided by two or more separate elements. Similarly, while the cross-section of the first and second plunger are described as having cross-shaped cross-sections, they may in fact have a range of differently shaped cross-sections in other examples. In some examples a locking mechanism may only be provided for one or other of the aspiration barrel and the injection barrel, and in alternative examples no locking mechanism is provided - for example the plungers described may be positioned and/or held in place by hand .

Although a spring is shown and described above, other biasing means are envisaged, for example a tensile element for providing a tension force on the plunger may be provided.

Alternative valve structures are also envisaged. Although a piston forming three seals with a casing is described above, other structures suitable for providing the described functionalities are envisaged, for example structures that enable the valve to transition between reverse, neutral and forward positions. Although a slider for operating the valve is described above, the valve may instead comprise a switch, rocker, button, trigger or other mechanism that enable the valve to be switched by hand between the different states described.

In the embodiments described above, fluid pressure in the system is controlled at the syringe. However, in other examples the pressurising/depressurising function and the storage/collection of injection and/or aspirated fluid may be provided at different parts of the system, for example by separate elements such as a pressure control element and a fluid storing element. In some examples means for determining the pressure in the system may be provided, for example by such a pressure control element. This may be configured to display in the system at a given time, e.g. pressure caused by the biasing means or by the aspirating apparatus .

In certain examples a controller described herein may be configured to perform any of the methods, or particular steps of said methods. The activities and apparatus outlined herein may be implemented using controllers and/or processors which may be provided by fixed logic such as assemblies of logic gates or programmable logic such as software and/or computer program instructions executed by a processor. Other kinds of programmable logic include programmable processors, programmable digital logic (e.g., a field programmable gate array (FPGA) , an erasable programmable read only memory (EPROM) , an electrically erasable programmable read only memory (EEPROM) ) , an application specific integrated circuit, ASIC, or any other kind of digital logic, software, code, electronic instructions, flash memory, optical disks, CD-ROMs, DVD ROMs, magnetic or optical cards, other types of machine-readable mediums suitable for storing electronic instructions, or any suitable combination thereof.

The above embodiments are to be understood as illustrative examples. Further embodiments are envisaged. It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the invention, which is defined in the accompanying claims.

Other variations and modifications of the apparatus will be apparent to persons of skill in the art in the context of the present disclosure.