DESCRIPTION

Field of the invention

The present invention relates to a kit comprising a medical device for minimally invasive surgical drainage. More specifically, the invention relates to a kit allowing to provide a surgical drainage for medical or veterinary use, which kit comprises a tube or catheter made of flexible and biocompatible plastic material equipped with a suitable connector, and a buttoned probe made of a plastically deformable metallic material. With the help of the buttoned probe brought out from a skin incision (piercing), the tube connected with an end to the probe can be inserted into a recess of an ulcer cavity thereby performing the “ulcer piercing” technique. Then, the tube can be closed on itself to form a ring in a self-locking manner after having cut it to the desired length, so as to create a closed ring (“piercing ring”) which keeps the ulcer cavity accessible to allow effective daily irrigation of the cavity.

Background of the invention

It is known that deep skin ulcers with hidden recesses or fistulas (this term meaning a pathological, tubular-shaped communication between two structures or between two body cavities, or between a cavity and the outside) represent a surgical problem. This surgical problem first of all requires an accurate debridement, i.e. an operation involving the removal of any suffering, devitalised, necrotic or contaminated tissue and any foreign bodies from the ulcer, the drainage of the recesses where the stagnation of the exudate can occur and the systemic treatment with specific antibiotics.

As a matter of fact, the inflammatory state of a skin ulcer, kept active by a critical bacterial contamination or by an infection, determines the chronicity of the lesion. Any treatment, local or systemic, aimed at controlling and reducing the inflammatory state revitalizes the tissue repair process, reduces exudate and lessens bacterial contamination. However, it is known that the main cause of persistence of a critical bacterial contamination or infection, after an adequate remediation of the infected or necrotic tissues, is stasis of the exudate.

Therefore, the surgical drainage of any recess, be it superficial or deep, of a complex skin lesion is an essential factor for the prevention of any stasis of the exudate, and therefore for the healing of the ulcer.

In particular, diabetic foot ulcers present a major challenge for wound care professionals. Diabetic foot, complicated by a deep contaminated ulcer, is a case that is frequently observed in hospital emergency rooms or surgical outpatient clinics. This condition is mainly the consequence of insufficient prevention programs in the territory and/or of inadequate and ineffective procedures, which fail to prevent any superficial wounds from progressing in the patient’s tissues to involve the deeper underlying spaces, up to involving, in the most severe cases, even the bones, thus causing osteomyelitis.

In the case of the diabetic foot, the clinical problem is quite delicate, because such a complicated ulcer can evolve into a more critical condition, which can compromise the integrity of the stability of the foot, leading to the need for more or less extended radical amputation surgical interventions. It has been documented in diabetic patients that ulcer healing is an independent predictor of patient survival and amputation-free survival (SM Taylor et al., JACS, 201 1 ; 212: 532-45).

In medical practice, a drainage or drain is device suitable for facilitating the outflow of liquids, secretions or gases from a pre-existing or newly formed body cavity. The same term also refers to the event associated with such a device, i.e. the leakage of organic liquid or air from a body cavity or from a particular area of the patient, such as a surgical wound, an operating field or an abscess cavity.

Drainage is normally used in surgery in the post-operative course of surgical interventions, or in the course of surgical interventions carried out for certain pathologies, and it is also used in presence of certain pathological states, such as ulcers, in order to eliminate any infected material from the site and facilitate the repair. In the most common forms, surgical drainage devices consist of tubes of flexible and generally transparent polymeric material (for example, silicone, PVC, latex, polyurethane or Teflon), which are appropriately positioned inside the site to be drained. Such devices are often provided with perforations on the end which is inserted into the site (distal end), and are connected to a collection point external to the patient. At the proximal end of these tubes, a gravity collection device (passive drainage) or a connection to a suction or vacuum system (active drainage) may be provided.

A surgical drainage device of the prior art is described, for example, in the European patent EP0872259 B1 (PORGES), relating to a surgical drain composed of a plurality of individual tubular ducts, welded two by two along a longitudinal line of their outer surface. The first conduit is also welded to the last one, to form groups of (preferably six) conduits. These tubes can be separated from each other by tearing them along these longitudinal lines of contact starting from the distal ends, in order to divide the drainage action into several points in the tissues or in the cavity to be drained.

Another example of device of the prior art is disclosed in United States patent application US2003/0069551 (Bradley, III et al.), which relates to a tubular multipurpose drain consisting of two side-by-side tubes, also welded longitudinally to each other. One of the tubes can be used to supply a gas or liquid for therapeutic purposes to the area to be drained, and the other one, provided with holes distributed on its surface, acts as a real drainage tube. The drainage tube can be connected, at the proximal end, to an aspiration system, so as to provide a closed system of irrigation and aspiration. Also in this case the two tubes can be separated from each other by tearing them along the longitudinal welding line starting from the distal end. Separating them, so as to avoid a “siphon effect”, in which the irrigation fluid it passes directly from the exit of the first tube to the inlet of the second tube without sufficiently irrigating the tissues of the affected area.

Furthermore, the published U.S. patent application US 2017/224967 discloses a drainage device comprising a tubular catheter, with a proximal and a distal end, which can be closed as a loop by means of a cylindrical connector, in order to go through an abscess cavity. The catheter tube has holes through which a solution for washing the abscess cavity should flow.

Finally, the published U.S. patent application US 2015/0250460 describes an example of a tubular device suitable for drainage but not for irrigation, to be used for the treatment of perianal fistulas. Also in this case the device is equipped with a connector for closing it as a ring.

With specific reference to diabetic foot, in the case of deep contaminated neuropathic ulcers, the current practice provides for the execution of an extensive surgical incision of the planes overlying the cavity itself, starting from the point where the cavity starting from the ulcer it communicates with the outside. The affected tissues are laid flat, so that the clinician can be able to carry out a daily open-air remediation. At the end of the long healing process of the surgical wound, the incision results in a long and annoying scar, often running along the plantar load bearing surface. As an alternative to the incision of the tissues overlying the cavity, it is possible to envisage the positioning of a tubular or flat Penrose type drain in the blind cavity, which however does not allow complete cleansing and irrigation of the drained cavity, thus facilitating the persistence of an infectious state.

As part of the research and clinical work on complicated neuropathic ulcers of diabetic foot, a new minimally invasive surgical procedure has recently been proposed (Cavallini M., 2014-2020, see below), called the “ulcer piercing” technique, which is illustrated for explanatory purposes in Figures 1a-1f of the accompanying drawings. In the ulcer piercing procedure, after carrying out the usual debridement operations of the deep skin lesion (Fig. 1a), the infected, narrow and tortuous recess is followed by means of a flexible stylet, a buttoned probe or other suitable instrument introduced into the opening of the fistula, driving the instrument all the way into the cavity. When the probe has reached the end of the recess, it is pushed towards the overlying skin where, under local anaesthesia (Fig. 1 b), the tissue between the skin and the tip of the probe is incised (pierced) with a lancet (counter-opening) (Fig. 1c), to make the probe come out. Subsequently, (Fig. 1d) a drainage tube is fixed to the end of the probe protruding from the counter-opening and is advanced backwards along the identified recess, and finally (Fig. 1e) the two ends of the drainage tube are tied together with two sutures, thus creating a closed ring (piercing ring). In this way, (Fig. 1f) inserting a syringe into one of the two openings in the tissues corresponding to the drain allows the clinician to insert the spout of a syringe for pressure irrigation of the recess, several times a day, with a disinfectant solution. It is thus possible to easily clean the entire recess, and to avoid stagnation of the exudate (Cavallini, M.: Ulcer piercing: Cleansing of complicated diabetic neuropathic foot ulcers by positive pressure irrigation, J. Wound Care 2014, 23(2): 50-65; Cavallini, M.: Wound piercing: a novel approach for deep cutaneous ulcer cleansing, Ann. Ital. Chir. 2014, 85(5): 505-510; Cavallini, M., Ulcer Piercing: A Novel Drainage Technique for Diabetic Patients with Complicated Foot, J. Endocrinol. Diab. 2015, 2(4): 1 -4; Cavallini M.: A Novel Drainage Technique for Deep Complicated Diabetic Foot: Ulcer Piercing, FIP World Congress of Podiatry Montreal 26-28 May, 2016; Cavallini M.: A Novel Mini-Invasive Drainage Technique To Treat Deep Diabetic Foot Phlegmon: Ulcer Piercing, EWMA 2017 Annual Conference, Amsterdam, 3 - 5 May 2017; Cavallini M.: A Novel Mini-Invasive Drainage Technique to Treat Deep Diabetic Foot Infection, 9 ^th Annual Abu Dhabi Wound Care Conference, February 10-1 1 , 2018; Cavallini M.: Mini-Invasive Drainage Technique To Treat Deep Diabetic Foot Infection, 8 ^th International Symposium on the Diabetic Foot, The Hague, May 22-25, 2019; Cavallini M.: Mini-Invasive Drainage and Irrigation Avoid Exudate Stasis, Reduce Recurrence Risk and Allow Better Rehabilitation for Deep Infected Diabetic Foot Ulcers, EWMA 2020 Annual Conference, 13 - 15 May, London, UK).

Summary of the invention

In the light of the prior art reported above, the need to have available an improved drainage device allowing to apply the ulcer piercing technique described above in a simplified, routine and non-artisanal way is evident. This technique is characterized by the notable advantages of requiring a minimally invasive surgical intervention, reducing the risk of recurrences with extensive scars and facilitating rehabilitation. For this purpose it is proposed, according to the present invention, to create a self-locking tubular device, capable of closing on itself in a ring without having to manually operate the tying necessary to keep the ring stable, so as to prevent the device from being accidentally removed during the dressing manoeuvers. To obtain this, the device according to the invention is provided, at one of its two ends, with a cylindrical and compact connection element, which allows to connect end-to-end the other free end of the drainage tube, by inserting it in a stable manner.

In this way, a self-blocking surgical drain is created, to be applied with a minimally invasive method, which keeps an infected tissue recess drained and, in addition, allows full canal irrigation several times a day of this recess. The irrigation may be carried out with solutions of crystalloid substances (i.e. aqueous solutions of mineral salts or other water-soluble molecules), with disinfectant solutions or with antibiotics, for the control and treatment of soft tissue infection. Irrigation is performed by placing the tip of a syringe containing the water or the solution to be dispensed into the skin accesses next to the drainage tube outlet. Furthermore, keeping the two openings of the fistula constantly open prevents the stagnation of the exudate and, therefore, it is possible to effectively reduce the bacterial load in the ulcer lesion.

The insertion of the drain according to the invention involves the exploration of a real cavity of the tissues, for example an abscess cavity or a phlegmon, by means of a specially configured plastically deformable buttoned probe. When the probe reaches the end of the explored cavity, its tip is directed towards the overlying skin and local anaesthesia is performed, for example with an injection of lidocaine, in the area where the incision will have to be made to let protrude the probe head. It should be noted that the blunt probe (buttoned probe) allows the recesses and abscess cavities to be followed and explored in the tissues where the infection is present, without creating false paths, as it would happen if an instrument with a pointed end were used. Thus, the use of the blunt probe allows the surgeon to find the most suitable point to make the distal incision for the exit of the probe.

Once the probe head comes out, the length of the section through which the probe has penetrated is evaluated, and the free part of the drainage tube is cut to the length necessary to create a ring that does not generate tension, or that is too wide, in the tissues thus identified. The head of the probe, being commensurate with the internal diameter of the drainage tube, is then pressed into the free end of the drainage tube of the invention, so as to stably catch the drainage tube. With a retrograde movement, the tube is led out from the inlet channel, and then its end is cut to size and connected to the connection element present on the other end of the tube. It is frequent the need to place up to 5-10 drains at the same time to allow adequate infection control.

According to another embodiment of the present invention, it has been considered that the irrigation procedure of the cavity corresponding to the drainage ring can be facilitated by connecting the ring tube to a system for connection to a syringe, allowing irrigation to be carried out directly through the ring tube. In this embodiment, the ring tube is provided with holes for delivery of the irrigation liquid.

According to a further embodiment thereof, the present invention proposes to carry out the irrigation by connecting to a non-perforated ring tube an irrigation system in parallel, comprising a connector to a syringe directly leading to an independent section of tube, suitable for dispensing the irrigation liquid inside the cavity corresponding to the ring tube.

In clinical practice, the procedure and the devices proposed according to the invention are indicated in all cases in which there is a real cavity in the superficial or deep tissues, with complex and branched recesses (post-haema- toma, post-traumatic, post-abscess or phlegmon), and in which there is a stagnation of exudate and the persistence of a critical bacterial contamination. Pathological conditions which may benefit from the procedure disclosed and from the devices according to the invention are mainly sacral, ischial, trochanteric or calcaneal decubitus lesions, diabetic foot phlegmons, perianal abscesses, pilonidal sinus abscesses and, more generally, abscesses of the soft tissues, covert surgical wounds infections, serous collections and post-traumatic hematomas of soft tissues, as well as erysipela from infected skin lesions and necrotizing fasciitis. Pressure irrigation of the recess kept open by the drainage tube is a manual operation easily performed by any caregiver even at the patient’s home.

In all patients the drainage ring is replaced at least monthly and, preferably, weekly or every other week, and is permanently removed once the drained recess appears completely covered with homogeneous granulation tissue. The drain is replaced by detaching the connector, which is then connected to the end of a new tube. The latter is led into the cavity, pushed out through the other access point, cut to size, and then connected to the connector at the other end of the new catheter. This procedure allows you to explore and evaluate the status and progression of the repair within the drained abscess cavity.

Brief description of the drawings

The specific characteristics of the invention, as well as the advantages thereof, will become apparent with reference to some of the specific embodiments thereof, illustrated in the figures attached hereto, in which:

Figures 1a-1f, already treated previously, schematically show the various phases of the minimally invasive surgical procedure of “ulcer piercing” for the drainage of deep skin ulcers, as described by the prior art;

Figure 2 schematically shows the irrigation operation of the recess of a deep skin ulcer extending onto the sole of the foot of a patient treated with the minimally invasive surgical procedure of “ulcer piercing” and the relative drainage;

Figure 3 schematically shows a foot affected by multiple deep neuropathic ulcers (Charcot's foot) treated with the minimally invasive surgical procedure of “ulcer piercing” and the relative drainage;

Figure 4 shows a side view of a probe or buttoned probe which constitutes an element of the kit for minimally invasive surgical drainage according to the present invention;

Figures 5a and 5b show two side views of a first embodiment of the medical device of the minimally invasive surgical drainage kit according to the present invention; Figure 6 shows a side view of a second embodiment of the medical device of the minimally invasive surgical drainage kit according to the present invention; and

Figure 7 shows a side view of a third embodiment of the medical device of the minimally invasive surgical drainage kit according to the present invention.

Detailed description of the invention

Therefore, the present invention specifically provides a kit for implanting a medical or veterinary device for minimally invasive surgical drainage of deep contaminated ulcers having complex and branched recesses, which kit comprises the following elements: a) a tube of flexible and biocompatible plastic material, with an internal diameter between 2 and 8 mm, preferably between 2 and 5 mm, having an open first end and a second end inserted on a biocompatible cylindrical connector having an external diameter such that it can be inserted under pressure into the first open end of said tube of flexible and biocompatible plastic material; b) a buttoned probe of plastically deformable metallic material, having a central section of a diameter between 2 and 3 mm, a blunt or rounded and preferably enlarged first end, and configured to engage under pressure in the open end of said tube, and a second end preferably flattened and expanded so as to facilitate grip and manoeuvering of said probe, wherein the external diameter of said first end of the buttoned probe is equal to the internal diameter of said tube of flexible and biocompatible plastic material.

For the production of medical devices such as catheters, a range of polymers are used, including silicone rubber, nylon, polyurethane, polyethylene terephthalate (PET), latex and thermoplastic elastomers. Silicone is one of the most common implantable choices, because it is inert and non-reactive to bodily fluids and a to range of medical fluids it may come in contact with. The presence of these materials is quite well tolerated by the body tissues, causing a negligi- ble inflammatory reaction. The consistency and flexibility of drainage tubes depends on the type of material and on the thickness of their wall. The rigidity of the tubes must be such as not to traumatize the tissues with which they come into contact.

Due to their inert nature, Silastic brand medical grade silicone elastomers are materials used in numerous pharmaceutical and medical devices, including catheters, pacemaker leads, tubing, wound dressings, etc.. For this reason, these elastomers represent the preferred material for making the drainage tube of the present invention.

As already noted, the buttoned surgical probe is a thin and elongated surgical instrument, with two ends: one blunt, rounded or with a small swelling, to be introduced into the cavity to be explored, and the other preferably flattened and expanded, so as to be more easily handled. The buttoned metal surgical probe is generally used in the exploration of fistulous tracts and surgical wounds and in post-traumatic tissue detachments, and has a length of between 14 and 25 cm, and a preferred diameter of 2-3 mm. For the application envisaged for the kit of the present invention, the probe is made of a plastically deformable metal material, and can have a length of between 15 and 30 cm, preferably 20- 30 cm.

It should be noted that the connection system proposed for the ring closure of the draining device according to the invention consists of a connector inserted inside the lumen of the tube, which fits into the other free end of the same without creating connections bulkier than the tube itself. The absence of bulky connections is of fundamental importance for the application of the minimally invasive drainage device of the invention to the treatment of complicated neuropathic ulcers of the diabetic foot. In fact, it is frequent in these patients to have to implant up to 5-10 drains at the same time to allow adequate control of the infection.

According to a further embodiment of the invention, the plastic material tube of element a) also comprises: c1 ) a Y-shaped branch near said second end of the tube, inserted on a hollow tubular connector, terminating in a luer lock access for an irrigation syringe.

In this embodiment, the tube of flexible and biocompatible plastic material which forms the ring drain is provided with multiple holes for irrigation through the tube itself.

According to a third embodiment of the invention, the plastic material tube of element a) also comprises: c2) an additional section of tube made of flexible and biocompatible plastic material, joined in parallel to said tube of plastic material of element a) near said second end inserted on said cylindrical connector, and ending in a luer lock access for an irrigation syringe. The additional section of tube is long enough to deliver the liquid contained in the syringe into the ulcer site.

The three embodiments of the medical device for surgical drainage according to the invention are described in detail, by way of example, in the following paragraphs. In the figures, corresponding elements are assigned the same reference number.

With reference to Figures 4, 5a and 5b, an example of the first embodiment of the kit according to the invention is schematically shown therein. In such example, the probe 1 of Figure 4 has a rounded and enlarged head 2, in order to be able to firmly connect with the end free 3 of the drainage tube 4, shown not to scale in Figures 5a and 5b. The surgical drain 4 is a small size silastic tube (3-10 French units, equivalent to 0.33-3 mm), of between 10 and 30 cm in length, Shore A hardness 35, equipped with a connector 5 (visible in Figure 5a) at one end, which allows to make a stable drainage ring, as shown in Figure 5b.

In the version of the probe 1 illustrated in Figure 4, the instrument has the second end 6 flattened and widened, so as to facilitate its handling.

With reference to Figure 6, an improvement of the surgical drainage according to the invention consists in creating an access, specifically a Y-shaped branch 7, provided with a luer lock connection 8 for a syringe 9, in order to allow irrigation of the fistula through the holes 10 made in the drainage tube 4. Once the lesion has been irrigated using the syringe 9, the access to the Y-branch 7 is closed with a sealing cap 1 1 . The enlarged detail to the side of Figure 6 shows a part of the same device with the drainage tube 4 closed to form a loop (not shown) and the syringe 9 inserted in the luer lock connector 8 of the branch 7 to carry out the irrigation.

With reference to Figure 7, another possible improvement of the surgical drainage device consists in creating an access for a syringe alongside the drainage ring, but independent of it, through which it is possible to irrigate the fistulous tract. For this purpose, the invention provides for an additional section of tube 12 of flexible and biocompatible plastic material, joined in parallel to the drainage tube 4 near the second end to be inserted on the tubular connector 5, but not communicating with it. The additional section of tube 12 is connected to a luer lock access 8, which allows a syringe 9 (not shown) to be inserted to perform irrigations through the section of tube 12. Also in this case, when not in use, the luer access lock 8 is closed by a suitable closing cap 1 1 (not shown). It should be noted that the section of tube 12 has such a length as to be able to dispense the liquid contained in the syringe into the ulcer site.

As in the case of the experimental ulcer piercing procedure described by the prior art, the devices of the present invention are applied as follows:

A) by means of the buttoned probe provided in the kit it is possible to follow any deep hidden infected tract;

B) when the probe reaches the end of the hollow, the probe is pushed towards the skin of the patient and, under local anaesthesia, the interposed tissue is punctured and incised;

C) a drainage tube is connected to the probe;

D) the probe is pulled backwards, taking the drainage tube with it;

E) the two ends of the drainage tube are connected together (to provide a piercing ring);

F) the insertion of a syringe into the skin openings kept open by the drainage ring allows an easy and adequate daily irrigation and cleansing of the tract, which can be also performed by any trained home assistant, by a family member or by the patient himself.

The surgical technique for positioning the device of the present invention is simple and easy to perform in an outpatient setting, and has no disadvantages other than having to perform an accurate haemostasis of the skin incision which allowed the probe to come out. Thus, a closed tissue cavity is changed into a cavity open at two ends, with an inlet opening and an outlet opening, which allows efficient irrigation of the cavity itself.

For these reasons, the technique forming the basis of the present invention is a minimally invasive solution which makes it possible to avoid more extensive and demolitive surgical solutions, employing large incisions and laying the tissues overlying the recess flat. By avoiding more extensive tissue scarring, this conservative procedure improves the rehabilitation phase and reduces the risk of recurrence.

Other clinical advantages of the ulcer piercing technique applied through the drainage device of the invention are the following:

• stability of the drainage, which cannot be accidentally removed during dressing manoeuvres;

• easy use at home by a home caregiver (nurse or trained family member) in performing daily irrigations;

• a minimally invasive procedure to treat superficial or deep tissue cavities;

• the use of untimely large surgical drainage incisions is avoided;

• the rehabilitation of the tissues involved is improved due to the presence of small skin scars;

• the incidence of recurrence of skin and tissue lesions is reduced, having avoided the formation of more extensive scars.

The present invention has been described with reference to some specific embodiments thereof, but it is to be understood that variations or modifications may be made to it by those skilled in the art, without departing from the scope of protection as defined in the appended claims.