Patent Description:
Each year several million patients present to emergency rooms seeking medical assistance for skin and soft tissue infections. A majority of these infections are subcutaneous abscesses, which are confined accumulations or collections of pus and dead tissue below the skin. Patients presenting with this common skin condition usually experience pain and can also present with fever or chills.

The treatment of abscesses is one of the most commonly performed hospital procedures. Some abscesses are 'simple' or 'pointing' and are almost ready to burst through the skin. These abscesses can typically be treated in an outpatient setting with local anaesthetic via an incision and drainage procedure. After administration of a local anaesthetic, a small incision is made at the site to puncture the skin. Contents of the abscess can then escape by draining out through the incision, sometimes assisted by manual expression of the contents by a clinician. Contents of the abscess may project upward and outward when excised and clinicians typically use personal protective equipment to mitigate risk of self-contamination.

Abscesses which are extensively large, deep, or which have thick or nonhomogenous contents can be more challenging to drain. Some can be drained using imaging guidance to place a needle, catheter or other suitable drain through the skin into the abscess to remove or drain the fluid collection. However, the drains most commonly inserted often become occluded with abscess contents and stop flowing before the entire contents have been cleared. The patient then requires surgery to open the abscess using a larger incision.

Presently, the majority of complex abscess cases presenting to hospitals are treated in theatre with surgery and under a general anaesthetic. Whilst surgical treatment generally resolves the problem of the abscess, it generates a series of new problems. Patients undergoing surgical abscess treatment typically require a one to two day hospital stay. They must be fasted prior to surgery and face the risks associated with administration of general anaesthesia. Surgical treatment of abscesses requires an incision that needs to be long and deep enough to allow access to the abscess cavity. Typically, the incision will extend across the entire diameter of the abscess and, consequently, scarring may become of concern to the patient. Further, the use of longitudinal force to penetrate skin and tissue to reach the abscess carries a risk of inadvertently puncturing underlying tissue structures.

Surgical treatment of abscesses is thus financially costly for the health care system and patient and also carries risks associated with surgery and administration of general anaesthesia.

Other medical procedures may similarly require access to a fluid collection site in the body of a patient to drain a fluid, which may be liquid or gas. At least some of these medical procedures share similar problems and risks to abscess drainage procedures.

<CIT> discloses a fenestration system that includes a drainage screwdriver, a drainage screw removably receivable onto the drainage screwdriver and a drainage cap removably coupleable with the drainage screw when the drainage screw is removed from the drainage screwdriver. The drainage screwdriver can receive the drainage screw so that the drainage screw can be screwed through tissue and/or a cyst or abscess sac. The drainage screwdriver can then release the drainage screw so that it is inserted into the tissue, cyst or abscess so as to be capable of drainage. A lumen in the drainage screw can function similarly to a drainage tube. The drainage cap can be applied to the drainage screw to close the lumen to inhibit other fluids or particles from entering into the tissue, cyst or abscess via the lumen.

<CIT> discloses a percutaneous minimally invasive stereotactic puncture treatment system for intracranial lesions. The treatment system comprises a puncture part, a guide part, a limit part and a drainage part. The drainage part comprises a drainage tube and an external drainage device. The puncture part is sleeved with the drainage tube and a drill of the puncture part is exposed. The guide part fixes the drainage tube and the puncture part in the puncture direction. The limit part controls the displacement of the drainage tube and the puncture part in the puncture direction. When a puncture is finished, the puncture part is removed from the drainage tube, and by connecting the external drainage device with the drainage tube, irrigation and drainage are achieved.

<CIT> discloses a surgical drain insertion device for insertion of a drain into a person's body. The drain insertion device comprises a penetrator having a head connected by a shank to a tip; and a duct concentric with the shank, which provides an opening through which a drainage tube can be inserted into the duct. The shank of the penetrator has a male threaded portion adjacent to the tip so that the penetrator can be rotated to separate muscle fibres to create a passage in the body wall of a person and to bring the drainage tube into fluid flow connection with the body cavity adjacent to said body wall. The duct is a bore through the penetrator, or may be formed by a sleeve around the penetrator. The device may include a securing means comprising a plurality of lugs.

<CIT> discloses an apparatus for inserting a thoracotomy tube in a patient without damaging adjacent lung tissues. The thoracotomy tube is adapted to receive a trocar having screw threads on the distal end thereof. The proximal end of the trocar has a handle thereon to rotate the trocar so that the screw threaded distal end forms an incision within the skin of the patient and the tip end of the screw thread passes into the pleural cavity. The distal end of the thoracotomy tube is provided with screw threads on the outer surface thereof to form a continuation of the screw threads of the trocar. The distal tip or end of the trocar terminates in a short flexible tube. A hollow needle extends through a central passageway in the trocar and through the flexible tip on the trocar. The opposite end of the hollow needle is provided with a pressure chamber which is in fluid communication with the passageway in the needle. In use, the trocar and thoracotomy tube are screwed into the body tissues of the patient and when the distal end of the needle enters the pleural cavity within the body, liquid within the pressure chamber passes through the hollow needle and into the pleural cavity. The release of the fluid from the pressure chamber is an indicator to the surgeon that the end portion of the needle has entered the pleural space. The trocar and thoracotomy tube are then screwed in as the needle is withdrawn from the flexible tip on the distal end of the trocar so as to prevent damage to any body tissues.

<CIT> discloses an apparatus for draining fluid from a body cavity that a housing having an integral cannula in permanent fluid communication with an outlet port, and an access port closed by a self-sealing elastomeric plug through which passes a removable needle. A tube attached to the outlet port includes a double check valve and pump port to permit aspiration of fluid from the cavity. The apparatus may include a flange and locking device on the cannula to fix the apparatus to the patient's body at a desired insertion depth.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each of the appended claims.

The invention is defined in the independent claim and other embodiments are listed in the dependent claims.

According to a first aspect, there is disclosed a percutaneous drainage device comprising a penetration component slidably engaged with a cannula. The penetration component has a piercing end adapted to penetrate tissue of a patient and introduce an open end of the cannula to a subcutaneous fluid collection site, wherein the cannula provides a passage through which a fluid collection may be drained from the patient. The percutaneous drainage device is characterised in that a length of the cannula is adjustable.

The penetration component may be slidably located in the cannula and be movable between a first position in which the penetration component is located concentric to the cannula; and a second position in which the penetration component is retracted and separated from the cannula. In one embodiment, the penetration component is located in a lumen of the cannula when in the first position.

The penetration component may have a threaded portion at or adjacent the piercing end. The threaded portion may be tapered towards the piercing end. The threaded portion assists the penetration component to drive or drill into the tissue of the patient in use, towards a subcutaneous fluid collection site. The threaded portion may have one or more thread turns.

The piercing end may optionally be provided with a cutting tool or pointed tip to create an initial incision into patient tissue. The cutting tool or pointed tip may be removed or retracted prior to driving or drilling the penetration component into patient tissue.

The piercing end may be driven into patient tissue by rotation of the penetration component about a longitudinal axis thereof. Rotation may be actuated by rotational manipulation of a handle, located at an end of the penetration component opposite to the piercing end. Rotation of the piercing end into patient tissue enables gradual stretching of tissue and smooth introduction of one end of the cannula into tissue and towards the subcutaneous fluid collection site.

The penetration component may be prevented from rotating inside the lumen of the cannula by a securing means. The cannula may also be rotated with the penetration component by rotational manipulation of the handle, thereby driving both penetration component and cannula into tissue of the patient.

The penetration component may have tight tolerance with the lumen of the cannula to generate a negative pressure during retraction of the penetration component from the cannula. This may assist with initial suction of fluid collection.

At least part of an outer surface of the cannula may be threaded to assist in drilling and thereby driving the percutaneous drainage device into patient tissue and towards the fluid collection site.

At least part of one or both of the penetration component and cannula may be comprised of a radiopaque material. The percutaneous drainage device may be provided with one or more radiopaque depth markings.

A length of the cannula may be adjusted following removal of the penetration component by cutting or snapping a frangible portion. A portion of the cannula may protrude from the skin of the patient following any adjustment of cannula length. The cannula may be removed from the patient following removal of the penetration component or remain in situ for a period of time.

The cannula may be secured in situ in the patient by an anchoring means. The anchoring means may comprise a clamp, such as a hinged clamp, which clamps around an outer circumference of the portion of cannula protruding from the patient. The anchoring means may also have an adhesive portion which may attach directly to skin of the patient immediately surrounding the cannula.

The percutaneous drainage device may be provided with a collection management component or collection vessel. The collection vessel is arranged in use to be in fluid communication with the cannula and receive fluid collection that drains from the patient through the cannula.

The collection vessel may attach to the anchoring means by a connector means, to enable attachment, removal and replacement of the collection vessel as required.

The collection vessel may include a pressure regulation means for generating negative pressure in the collection vessel, which may include a valve means.

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

In the drawings, like reference numerals designate similar parts.

Embodiments of a percutaneous drainage device will now be described by way of example only.

Referring initially to <FIG>, there is shown a percutaneous drainage device <NUM> having application in drainage of a subcutaneous fluid collection from a patient. The percutaneous drainage device <NUM> is useful for and will be described primarily in the context of draining an abscess. However, it should be understood that the percutaneous drainage device <NUM> of the present disclosure has utility in gaining access to and drainage of any subcutaneous fluid collection and that the subcutaneous fluid collection may be liquid and/or gas. In the context of drainage of an abscess, 'fluid collection' refers to a collection of pus, liquefied tissue and any other associated liquid held within the confines of an abscess wall.

The percutaneous drainage device <NUM> comprises a cannula <NUM> having a lumen <NUM>, a first open end <NUM> and an opposing second open end <NUM>. The cannula <NUM> may be slidably engaged with a penetration component <NUM> comprising an elongate shaft <NUM> having a handle <NUM> at one end and an opposing piercing or drilling end <NUM>. The penetration component <NUM> is movable between a first position in which the cannula <NUM> is concentric to the elongate shaft <NUM> of the penetration component <NUM>; and a second position in which the penetration component <NUM> is retracted from and separated from the cannula <NUM>, as shown in <FIG>. In the first position, the penetration component <NUM> may be located substantially inside the lumen <NUM> of the cannula <NUM>, as shown in <FIG>.

In the embodiment shown in the Figures, the penetration component <NUM> may be prevented from rotating inside the lumen <NUM> of the cannula <NUM> when in the first position by a securing means. In the embodiment shown in <FIG>, the securing means comprises one or more grooves <NUM> disposed on a surface of the lumen <NUM> adjacent the second open end <NUM> of the cannula <NUM>. The one or more grooves <NUM> engage with one or more corresponding ribs <NUM> disposed on an end of the penetration component <NUM> adjacent the handle <NUM>.

A first embodiment of the penetration component <NUM> is shown in <FIG>. In this embodiment, the penetration component <NUM> comprises an elongate shaft <NUM> with a handle <NUM> at one end and an opposing drilling or piercing end <NUM>. In the embodiment shown in <FIG>, the piercing end <NUM> is a cutting tool, such as a small blade.

A second embodiment of the penetration component <NUM> is shown in <FIG>, where the piercing end <NUM> comprises a pointed tip. The piercing end <NUM> can be used to pierce or perform an initial incision into skin and tissue of the patient, creating an initial aperture. The cutting tool or pointed tip may be retracted or otherwise removed prior to driving or otherwise further introducing the percutaneous drainage device <NUM> into the tissue of the patient and towards a subcutaneous fluid collection site.

The elongate shaft <NUM> of the penetration component <NUM> has a threaded portion <NUM> at or adjacent the piercing end <NUM>. In the embodiments shown, the threaded portion <NUM> is tapered towards the piercing end <NUM>, providing a tapered tip with a helical ridge on a surface thereof. At least part of the threaded portion <NUM> extends outwardly from the first open end <NUM> of the cannula <NUM> when the penetration component <NUM> is in the first position. The threaded portion <NUM> may have one or more thread turns.

The threaded portion <NUM> provides the ability to drill and drive into the body of the patient when the penetration component <NUM> is rotated about the longitudinal axis. This rotation and initial driving of the threaded portion <NUM> of the penetration component <NUM> steadily and gradually stretches and increases the aperture of the initial incision. As the penetration component <NUM> is drilled and driven into the body of the patient, the aperture of the initial incision can be increased to a size that enables smooth introduction of the cannula <NUM>.

The threaded portion <NUM> can be drilled and driven into tissue by rotation of the elongate shaft <NUM>. Rotation is actuated by rotational manipulation of the handle <NUM>. This mechanism advantageously requires low or minimal longitudinal force to create a passage through the tissue overlying the abscess. Application of minimal longitudinal force can mitigate risk of accidental puncture or damage to the patient.

The penetration component <NUM> has a tight tolerance with the lumen <NUM> of the cannula <NUM> so as to in use, generate a negative pressure during retraction of the penetration component <NUM> from the cannula <NUM>. A portion of the elongate shaft <NUM> of the penetration component <NUM> may have a bulge portion (not shown), having an outer diameter which is larger relative to the remainder of the elongate shaft <NUM>, to further reduce tolerance with the cannula <NUM> and form a seal therein. The bulge portion can be located adjacent the threaded portion <NUM>. The bulge portion may, in use, further assist in generation of a negative pressure when retracting the penetration component <NUM> from the cannula <NUM>. This may assist with initial suction of fluid collection once the percutaneous drainage device <NUM> has been appropriately positioned in the patient tissue and fluid collection site.

The cannula <NUM>, an embodiment of which is shown in <FIG>, comprises an elongate hollow cylinder <NUM> which may be flexible or rigid. The cannula <NUM> may be made from a bio-stable or bio-resorbable material which can be cut by a standard surgical cutting implement such as scissors. Alternatively, the cannula <NUM> may be made from a material which can be snapped or broken. The cannula <NUM> may be snapped or broken along one or more frangible portions disposed at intervals along the length of the elongate hollow cylinder <NUM>. The length of the cannula <NUM> may therefore be adjusted as required by cutting or snapping along the length of the elongate hollow cylinder <NUM>.

The lumen <NUM> of the cannula <NUM> may have a diameter comparable to a diameter of the elongate shaft <NUM> of the penetration component <NUM>. The diameter of the lumen <NUM> may be sufficiently large to enable flow and drainage of fluid collection from the body of a patient with minimal risk of blockage.

The cannula <NUM> may be concentric to the elongate shaft <NUM> of the penetration component <NUM>. When in the first position, the elongate shaft <NUM> may sit inside the lumen <NUM> and at least part of the piercing tip <NUM> of the penetration component <NUM> may extend outwardly from the first open end <NUM>, as shown in <FIG>. The first open end <NUM> may have a bevel or chamfer to provide a smooth transition with the penetration component <NUM> when in the first position and when the percutaneous drainage device <NUM> is driven or otherwise introduced into patient tissue.

At least part of an outer surface of the cannula <NUM> may be threaded, providing a threaded surface <NUM>. In the embodiment shown in the Figures, a majority of the outer surface is threaded. The threaded surface <NUM> can assist drilling and driving of the percutaneous drainage device <NUM> into patient tissue. The cannula <NUM> with penetration component <NUM> located and fastened therein by securing means can be driven into tissue by rotational manipulation of the handle <NUM>.

The cannula <NUM> may be provided with one or more castellations or orifices <NUM> adjacent the first open end <NUM> to prevent vacuum sealing when the cannula <NUM> is in contact with tissue. The cannula <NUM> may also be provided with markings <NUM> on the outer surface to provide guidance on depth location of the abscess. The markings <NUM> can be etched, printed, indented or otherwise provided on the surface of the cannula <NUM>.

At least part of one or both of the penetration component <NUM> and cannula <NUM> may be comprised of a radiopaque material. One or more radiopaque depth markings (not shown) may be present on the surface of the cannula <NUM>. The percutaneous drainage device <NUM> may therefore be introduced and guided into the patient and towards and into the subcutaneous fluid collection site with imaging guidance such as ultrasound.

The percutaneous drainage device <NUM> may be further provided with an anchoring means <NUM> or anchoring subassembly. In the embodiment shown in <FIG>, the anchoring means <NUM> comprises a hinged clamp <NUM> comprising a pair of semi-cylindrical or semi-circular portions or halves <NUM>, hingedly connected to each other. The semi-cylindrical portions <NUM> are movable between an open position, shown in <FIG>, and a closed or locked position, shown in <FIG>.

The semi-cylindrical portions <NUM> can be locked in the closed position by a securing means, such as a simple latch mechanism. Once locked, the semi-cylindrical portions <NUM> form a cylinder or circle having an interface or inner surface <NUM> with a circumference comparable to an outer circumference of the cannula <NUM>. The semi-cylindrical portions <NUM> can be made from a rigid material whereby when the hinged clamp <NUM> is in a closed position, the inner surface <NUM> provides a rigid interface.

The anchoring means <NUM> further includes an adhesive portion <NUM>, extending radially outwardly from the semi-cylindrical portions <NUM>. In the embodiment shown, the adhesive portion <NUM> comprises an adhesive pad, disposed perpendicularly to the axes of the semi-cylindrical portions <NUM>. The adhesive pad may be flexible and attaches directly to the patients skin.

The hinged clamp <NUM> with inner surface <NUM> may clamp around the elongate hollow cylinder <NUM> of the cannula <NUM>. The hinged clamp <NUM> may be fastened in place around the cannula <NUM> by suitable means such as friction fit or adhesive. Alternatively, the inner surface <NUM> may be threaded or have other suitable configuration so that it can be mechanically attached to the cannula <NUM>.

The anchoring means <NUM> may be further provided with a connector means to enable the anchoring means <NUM> to connect to a collection management component or collection vessel <NUM>. In the embodiment shown in <FIG> and <FIG>, the connector means comprises a pair of flanges <NUM>, extending radially outwards from an end of the cylinder or circle formed when the semi-cylindrical portions <NUM> are in the closed position. The flanges <NUM> are adapted to slot into a corresponding aperture <NUM> in a wall of the collection vessel <NUM>. Once the flanges <NUM> are inserted through the aperture <NUM> and into an interior of the collection vessel <NUM>, the collection vessel <NUM> can be rotated, securing the collection vessel <NUM> onto the anchoring means <NUM> by a twist lock mechanism. The collection vessel <NUM> can be removed by counter-rotation and pulling the flanges <NUM> out of the aperture <NUM>. The collection vessel <NUM> may therefore be changed or replaced as required.

One embodiment of the collection vessel <NUM> is shown in <FIG>. In this embodiment, the collection vessel <NUM> comprises a hollow container or reservoir having a rear wall <NUM> through which the aperture <NUM> is located. A front wall <NUM> of the collection vessel <NUM> may have markings <NUM> on an outer surface thereof, which can be printed, etched or labelled to provide guidance on the quantity of collection discharged from the abscess. The collection vessel <NUM> has a slim or flattened configuration to minimise the amount of protrusion from the body of the patient. In one embodiment, the collection vessel <NUM> has size and configuration so as to protrude no more than about <NUM>, ideally no more than <NUM>, from the patient's body.

The collection vessel <NUM> may be a rigid, semi-rigid or absorbent reservoir. If rigid or semi-rigid, the collection vessel <NUM> may have means for providing negative pressure, to assist in suction of fluid collection from the patient once the percutaneous drainage device <NUM> has been appropriately positioned in the patient. The collection vessel <NUM> may be provided with one or more apertures <NUM> to equalise atmospheric pressure in the collection vessel <NUM>.

The collection vessel <NUM> may include a pressure regulation means (not shown) for generating negative pressure inside the collection vessel <NUM>. In one embodiment, the pressure regulation means may include a valve <NUM>. The valve <NUM> may be a one-way valve. The clinician or other operator may compress or inwardly press a deformable part of the collection vessel <NUM> or a part thereof to expel gas from the collection vessel <NUM> through the valve <NUM>. As the collection vessel <NUM> or part thereof begins to return towards an undeformed state, negative pressure is created inside the collection vessel <NUM>, providing suction of collection fluid through the cannula <NUM> and into the collection vessel <NUM>.

Referring to <FIG>, there is shown a sequence of steps of use of the percutaneous drainage device <NUM> of the present disclosure, though it should be understood that the sequence of steps may vary depending on clinician preferences. The abscess or other fluid collection present in the patient is first located by the clinician. Following administration of a local anaesthetic around the target site, an initial incision is made into the tissue, either by a conventional scalpel (step 2a) or by the piercing tip <NUM> of the penetration component <NUM>. Once the initial incision is made, the piercing tip <NUM> may be retracted or otherwise removed prior to driving the percutaneous drainage device <NUM> into the tissue of the patient.

The clinician may then commence driving the percutaneous drainage device <NUM> into the tissue by manual rotation of the handle <NUM> and penetration component <NUM> with surrounding cannula <NUM> (steps 3a and 3b). Driving and positioning of the percutaneous drainage device <NUM> in the patient may be assisted by imaging guidance, such as ultrasound or fluoroscopy. The threaded portion <NUM> of the penetration component <NUM> assists the driving function of the percutaneous drainage device <NUM>, converting torsional energy into linear motion. Advantageously, this can provide greater positional control whilst simultaneously reducing need for downwards force into the tissue. As the penetration component <NUM> is driven into the tissue, the threaded portion <NUM> gently stretches cutaneous tissue onto the cannula <NUM> which may assist in reducing site morbidity. Threading on the surface of the cannula <NUM> may also assist the percutaneous drainage device <NUM> to drive further into the tissue and towards the target fluid collection site.

The clinician may determine that the first open end <NUM> of the cannula <NUM> has reached the target fluid collection site by imaging guidance. Once the first open end <NUM> of the cannula <NUM> has reached the abscess or target fluid collection site, the clinician may grasp the handle <NUM> of the penetration component <NUM> and pull away from the body of the patient to retract the penetration component <NUM>, removing it from the cannula <NUM> (step <NUM>) through the second open end <NUM>. The clinician may further confirm that the first open end <NUM> of the cannula <NUM> is appropriately positioned in the target fluid collection site by visually observing presence of pus or other fluid upon retraction of the penetration component <NUM>. The tight tolerance between the penetration component <NUM> and cannula <NUM> generates a negative pressure during retraction of the penetration component <NUM> from the cannula <NUM>, initiating suction and flow of fluid collection from the abscess and into the lumen <NUM> of the cannula <NUM>. The cannula <NUM> thereby provides an extraction pathway through which the abscess contents may drain from the patient's body.

Holding the cannula <NUM> in place with the bevelled or chamfered first open end <NUM> positioned in situ in the abscess or target fluid collection, the length of the cannula <NUM> can be trimmed as required. The cannula <NUM> may be cut to size using scissors (step <NUM>), or snapped along an appropriate frangible portion. The cannula <NUM> may be trimmed so that a small portion remains protruding from the skin of the patient. The portion of cannula <NUM> protruding from the skin of the patient may be sufficiently long to enable attachment of the anchoring means <NUM>.

The cannula <NUM> is held in place and secured to the patient by the anchoring means <NUM>, which is attached to the portion of cannula <NUM> protruding from the patients skin. In the embodiment shown in the Figures, the hinged clamp <NUM> with rigid inner surface <NUM> is attached to the portion of cannula <NUM> protruding from the patients skin. The hinged clamp <NUM> may be positioned on the cannula <NUM> such that the pair of flanges <NUM> extend radially from the outermost end of the cannula <NUM>. The adhesive portion <NUM> of the anchoring means <NUM> may be attached directly to the patients skin.

The dual attachment of the anchoring means <NUM> to both the cannula <NUM> and the patient's skin provides an anchor to maintain the cannula <NUM> in position and to attach the collection vessel <NUM> if required. The collection vessel <NUM> may be attached to the anchoring means <NUM> by the connector means. In the embodiment shown, the flanges <NUM> of the anchoring means <NUM>, which extend radially from the outermost end of the protruding cannula <NUM>, are aligned with and pushed through the corresponding aperture <NUM> in the wall of the collection vessel <NUM>. The collection vessel <NUM> is then rotated approximately <NUM>° to lock the collection vessel <NUM> onto the anchoring means <NUM>.

The clinician may activate the pressure regulation means to generate negative pressure inside the collection vessel <NUM>. The clinician can compress the deformable part of the collection vessel <NUM>, reducing the volume inside the collection vessel <NUM>, expelling air through the valve <NUM> and generating negative pressure. As the collection vessel <NUM> returns to an undeformed state and pressure begins to equalise inside the collection vessel <NUM>, fluid is suctioned out of the fluid collection site and into the cannula <NUM>.

With the collection vessel <NUM> so attached and in fluid communication with the cannula <NUM> via aperture <NUM>, collection fluid may travel from the patient's body through the cannula <NUM> and into the collection vessel <NUM> (step <NUM>). The cannula <NUM> may remain percutaneously in situ for a period of time, typically up to seven days, or until such time as it is deemed that the fluid collection has been appropriately drained. The cannula <NUM> thus acts to maintain an opening in the skin and subcutaneous fat to permit drainage of the fluid collection over time.

Alternatively, the cannula <NUM> can be removed shortly after removal of the penetration component <NUM>. Prior to removal, the cannula <NUM> can provide a passage through which fluid, comprising liquid and/or gas, may exit or drain from the patient. Following removal of the cannula <NUM>, a passage created in the tissue by introduction of the percutaneous drainage device <NUM> may still permit drainage of fluid from the patient.

Markings <NUM> on the outer surface of the collection vessel <NUM> provide an indication of how much fluid has been drained from the patient. The collection vessel <NUM> can be detached and removed from the anchoring means <NUM> when desired. The collection vessel <NUM> may be discarded or sent to a laboratory for analysis of the contents. If further fluid is to be drained, the removed collection vessel <NUM> can be replaced by a fresh collection vessel <NUM>. The percutaneous drainage device <NUM> of the present disclosure thus combines percutaneous access and drainage of an abscess as well as ongoing management of the abscess contents during healing.

Once it has been determined that the abscess has been sufficiently drained, the cannula <NUM> may be removed from the patient. All components of the percutaneous drainage device <NUM> may be discarded following use.

The percutaneous drainage device <NUM> of the present disclosure, when placed percutaneously substantially as described above, advantageously provides a low pressure channel and passage for thick, complex collections comprising any combination of pus, debris and dead tissue, to flow out from within the subcutaneous abscess.

The percutaneous drainage device <NUM> of the present disclosure conveniently provides all the components required to offer a minimally invasive therapy that can be used to treat an abscess. A clinician using the percutaneous drainage device <NUM> can quickly and easily drain an abscess or other similar subcutaneous fluid collection in a setting which does not require hospital admission. The percutaneous drainage device <NUM> of the present disclosure therefore advantageously shifts the treatment of abscesses and other subcutaneous fluid collections from a high-cost setting requiring hospital inpatient admission, theatre time and associated patient risk, to a relatively low-cost outpatient procedure with reduced clinical care time and associate patient risk.

The following series of tests were performed, using embodiments of the penetration component <NUM> with specifications as set out in Table <NUM> below.

Each penetration component A-D was tested to determine (i) ability to enter and drive into tissue upon application of rotational force; (ii) whether or not an initial incision was required; (iii) level of damage or twisting to skin; and (iv) how easy the penetration component could be removed from the tissue. The results of these tests are also included in Table <NUM> above. Each penetration component was tested on an upper thigh region of a fresh frozen cadaver.

In each case, an initial incision in the skin was required prior to introducing the piercing point of the penetration component. Test penetration components A and C caused twisting of the skin upon entry, indicating that they could cause damage to the surrounding tissue. Test penetration components B and D showed less damage to the skin, with test penetration component D causing the least damage.

Test penetration components A and B were able to drive into the tissue only after application of axial pressure. Test penetration component A required application of significant axial pressure and reached a depth of <NUM> only. Test penetration component B required initial application of axial pressure but started to drive into the tissue once a depth of about <NUM> was reached. Test penetration component C was able to tunnel into the tissue to a depth of about <NUM> with application of rotational force only. Minimal axial pressure was required to drive further to a measured depth of about <NUM>. Test penetration component D required little or no axial pressure to commence and continue driving into the tissue.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claim 1:
A percutaneous drainage device (<NUM>) comprising a penetration component (<NUM>) slidably engaged with a cannula (<NUM>), the penetration component (<NUM>) having a piercing end (<NUM>) arranged to penetrate tissue of a patient and introduce an open end (<NUM>) of the cannula (<NUM>) to a subcutaneous fluid collection site, wherein the cannula (<NUM>) provides a passage through which a fluid collection may be drained from the patient;
wherein the penetration component (<NUM>) is movable between a first position in which the penetration component (<NUM>) is located concentrically within the cannula (<NUM>) and a second position in which the penetration component (<NUM>) is retracted and separated from the cannula (<NUM>);
wherein the penetration component (<NUM>) is located in a lumen (<NUM>) of the cannula (<NUM>) when in the first position, characterised in that the penetration component (<NUM>) has a tight tolerance with the lumen (<NUM>) and generates a negative pressure during retraction of the penetration component (<NUM>) from the cannula (<NUM>).