Patent Description:
Wound irrigation is considered a salient feature of clinical management in treating chronic open wounds, decubiti, vascular ulcers, and wound breakdown. The critical elements of the method are delivery, volume of fluid, and solution additives. Delivery can include powered/mechanical pumps, pressure canisters, thumb operated bulb syringes, piston syringes, plastic bottles that are hand squeezed for spray from a nozzle, and simply pouring fluid from a kidney basin. An important consideration is the aerosolized particles that can result from the splatter effect of high flow and pulsatile irrigation systems. This can expose the patient and healthcare professionals to air-born contaminants. Documented studies have shown that <NUM>% of the skin and mucous membrane seeding occurs to the eyes usually resulting from inadequate use of federally mandated eye protection. Contamination of the eye conjunctiva has been well documented with HIV virus and Hepatitis C infections from the splash effect.

The optimal pressure and rate of fluid flow remains controversial as high flow is considered important to dislodge bacteria and the biomass film created by the bacteria. High pressure is considered to range from <NUM> to <NUM> kPa (<NUM> to <NUM> PSI). While this level of force is considered adequate to remove bacteria, soft tissue damage, impaired immune response, and forcing debris deeper into the wound are hazards. Experts have concluded that <NUM> to <NUM> kPa (<NUM> to <NUM> PSI) of fluid pressure is adequate to dislodge bacteria eliminating the other effects. Studies comparing the efficacy of pulsatile lavage versus other flow types are inconclusive, but one study showed pulsatile flow was clearly less effective compared with at least one other type of flow (elucidated with respect to the invention described herein) in clearing Staph. aureus in infected rabbit wounds. The optimal volume of fluid irrigation is also inconclusive but lavage of up to <NUM> liters of fluid in large open wounds has been recommended. For reference in this specification, <NUM> kPa is equal to <NUM> pounds per square inch (PSI), <NUM> PSI is equal to <NUM> kPa, <NUM> PSI is equal to <NUM> kPa and <NUM> PSI is equal to.

Additives have included a variety of antiseptics including hydrogen peroxide, chlorhexidine gluconate (CHG), sodium hypochlorite, and parachloroxylenol but FDA clearance has been limited by lack of conclusive benefit and the possible toxicity to local host cells when higher concentrations are used. Cell and tissue culture studies with povidone-iodine and sodium hypochlorite have shown that they can be diluted sufficiently to mitigate the tissue toxicity effects without elinlinating their bactericidal activity; however, these diluted concentrations were significantly lower than is typically used in clinical practice. Similar dilutional studies with hydrogen peroxide and acetic acid have shown that they lose their bactericidal activity before they lose their tissue toxicity. It is notable that the only antiseptic currently with FDA clearance for debriding and cleansing wounds is an irrigation fluid containing sterile water and <NUM>% CHG in a medical device. A recent study of the use of <NUM>% CHG with sterile water as an irrigation solution against selective gram-positive and gram negative surgical isolates, including methicillin-resistant Staphylococcus aureus, revealed a <NUM>- to <NUM>-log reduction in bacteria recovery at <NUM> and <NUM> minutes. Additionally, significant reductions (P values ranging from <. <NUM> to <. <NUM>) in bacterial recovery from the surface of <NUM> different biomedical devices were seen when exposed to the same irrigation solution. Irrigation with this combination prior to wound closure could have a significant impact on the risk of surgical site infections.

In surgical wound debridement, a prominent industry has developed around the use of a mini-piston pump that is battery operated and can be delivered to the surgical field with a sterile and disposable hand held apparatus. The pump is a simple volume displacement device that has one piston cylinder, resulting in a variable pressure throughout the pump cycle. Pressure is reduced by the suction cycle of fluid inflow. This characteristic drives a cyclic pulsatile flow of fluid that has been advocated to debride the wound and remove foreign biomass produced by bacteria.

An important consideration is to understand the physics of fluid mechanics by which these pulsatile systems operate. The battery powered mini-piston pump functions much as any piston system where there is a drive shaft, in this case driven by a small electrical motor powered by a battery pack. The piston system passively draws in fluid from the reservoir system and then drives this fluid downstream into the pump channel that delivers the fluid to the wound. For this system, the pump is powered to create a maximum displacement force that can be measured in pounds per square inch. This has been established by FDA guidelines to have a ceiling of <NUM> kPa (<NUM> PSI). Therefore, whatever the speed of the pump or revolutions per minute, the pump pressure remains fixed by the force of displacement of the piston. The variables of performance can be altered by the flow rate determined by the revolutions of the pump and the velocity of flow. Flow velocity is determined by the inner dimensional area of the tube which the fluid passes to exit at the pump tip and be sprayed onto the wound.

The other factor to consider is the splatter effect magnified by the pulsatile flow. Again, the pressure of the piston pump is constant causing the same splatter effect even at lower RPMs. The pulsatile flow effect is minimally seen in the peristaltic pumps at lower RPMs and disappears at higher RPM's. As fluid is incompressible, the pressure drops very slightly with the wave drawing fluid behind the fluid roller. This allows for a steady continuous stream flow of fluid from the tip which some believe is more effective at removing biomass compared to the pulsed stream. To reiterate, the pump pressure remains the same at the high and low speeds that the piston pump operates, but the amount of fluid that the pump moves changes as a function of pump speed or revolutions per minute. In actual practice, there may be a limit to the amount of piston RPM's possible.

The pulsatile irrigation systems are single use because the pump, tubing and handle come into contact with the operating field adjacent the wound site, which thereby renders these elements non-sterile. This happens dramatically in surgery, where a combined suction-irrigation instrument is relied upon to siphon-off spent irrigation solution while allowing continued free access to the surgical site, yet there remains considerable splattering of operating room personnel (of whom most wear head gear with face shields), because the surgical wound site is not enclosed. Even where a shielding enclosure is employed post-operatively on an outpatient basis, the irrigation instrument becomes contaminated within the operating field defined by the enclosure, thus it must be discarded after a single use. The piston pump is in fluid communication with the instrument and exposed to spent irrigation solution during the procedure and this must also be thrown away, whether or not the pump is within or adjacent the irrigation instrument. In fact, pulsatile irrigation-suction guns have been used in combination with enclosure bags on outpatient procedures, as will be explained in the section immediately below, although the suction feature is often disabled by cutting off the hose leading into the pulsatile gun. Moreover, the predominant pulsatile gun models on the market are actuated by a finger trigger that controls the pump pressurizing fluid in the gun.

Some have sought to contain the backsplash emanating from the wound site being irrigated, by providing barriers, e.g., transparent bags, which surround the operating field. However, these barriers remain complicated, expensive and/or inadequate in the main, as well as the systems where used. These still leave problems of pulsatile irrigation unresolved.

<CIT> discloses a handpiece for a surgical irrigation and suction device that includes a trigger operated valving mechanism which controls the release of irrigation fluid. The valving mechanism includes a flexible tube which defines a portion of the irrigation conduit. The valving mechanism further includes a hook and rib arrangement in which the flexible tube can be drawn into a V-shaped kinked configuration which closes off flow through the tube. The spring is connected to a trigger which, when squeezed, shifts positions of the spring to release the kink and permit liquid flow. An irrigation wand may be provided with a special nozzle which directs a plurality of streams of irrigation fluid in a single plane spray pattern. A retainer clip may be provided to prevent inadvertent separation of the wands.

<CIT> discloses an irrigation system that includes an elongated, hand-held instrument for applying a solution spray to a surgical area of a patient during surgery. The instrument includes an elongated handle having an outer ribbed surface to be hand-held. The handle has a central passageway between an inlet end and a discharge end. A nose is secured to the discharge end of the handle with a flow control valve secured within the handle. Nozzles are selectively connected to the nose to create selected flow patterns at the surgical site. The valve has an external pushbutton actuator to control the solution flow through a passageway in the body and nose. A pressurized liquid supply includes a sealed disposable, liquid solution filled bag and a sterile tube connected to the inlet end of the body. The solution bag is releasably supported within a pressurizing bag which in turn is carried on a portable stand unit. A bulb pump or small pressurized cannister is coupled to the pressurizing bag, with a regulating valve, for establishing a pressure of about <NUM> to <NUM> therein. The irrigating solution flow is applied to the wound at about <NUM> to <NUM> kPa (<NUM> to <NUM> psi). The solution bag, instrument and interconnected elements are all throw-away elements providing a sterile one-time irrigating apparatus.

<CIT> discloses a solid cone spray nozzle with a mouthpiece having an outlet chamber and an inlet opening emanating from the outlet chamber and having a smaller cross-section than the latter. An inlet opening into the outlet chamber has a smaller cross-section than the outlet chamber and downstream of the outlet chamber inlet opening is provided a web-like preatomizer element on which impacts at least partly a fluid jet following entry into the outlet chamber. It also discloses its use e.g. as a two-fluid spray nozzle for spraying or atomizing low viscosity liquids for cooling purposes in billet or bloom continuous casting installations.

<CIT> discloses a nozzle tip of a spray gun of the airless type in which a slot is formed at a forward end of the nozzle tip which has a bottom at which a nozzle orifice opens and two opposite walls disposed parallel to each other and along the major axis of the nozzle orifice, each wall having an inner surface inclined outwardly in going from bottom to top so that the slot is trapezoidal in cross-sectional shape. The nozzle orifice at its edge is substantially in the form of a rectangle with four sides thereof being slightly curved outwardly, and a connecting portion between the nozzle orifice and a passage for the paint inside the gun is elliptically curved, the degree of elliptic curving varying depending on the specific gravity and viscosity of the paint used.

<CIT> discloses a wound treatment apparatus including a flexible transparent envelope of generally elongated configuration having a first end and a second end, a primary opening at the first end of the envelope, the primary opening having a peripheral margin therearound, the margin including a securement band for securement of the flexible envelope to a portion of the body being treated. The apparatus includes a first access port through the envelope, a wound fluid applying gun having an elongated barrel juxtaposable in a close fitting relationship to the first access port, to supply a pressurized wound treatment fluid onto any body portion attached to the envelope, and a drain port in communication with a collection chamber for draining any effluent fluid, tissue and/or gas from that envelope.

<CIT> discloses a sealed dirt-collecting pulse debridement system. The sealed dirt-collecting pulse debridement system comprises a pulse flusher, wherein the pulse flusher is provided with a nozzle which is used for conveying pulse flushing fluid. The sealed dirt-collecting pulse debridement system is characterized in that the pulse debridement system further comprises a sealed dirt-collecting debridement bag which is matched with the pulse flusher in use, the sealed dirt-collecting debridement bag is provided with a sealed bag body for supplying sealed flushing space, an inlet, a nozzle inserting pipe which is connected with the nozzle in an installing and matched mode, a waste liquid discharging pipe which is used for discharging flushing waste liquid and a waste liquid collecting bag which is used for collecting the flushing waste liquid, the sealed bag body is provided with an opening which can adequately surround the flushed affected part, a bag body adhesive sticker which surrounds the opening is arranged on the sealed bag body, an outlet of the nozzle inserting pipe is communicated with the sealed bag body and faces towards the opening, and the waste liquid discharging pipe is communicated with the sealed bag body and the waste liquid collecting bag.

<CIT> discloses an apparatus for irrigating and draining body wounds of patients or animals, having a base plate, which can be sealingly fixed to the area surrounding a wound and which has an opening for the passage of tubes and lines and which is provided with a closed bag fixed or fixable in sealing manner to the base plate and which is provided with an opening in the fixing area.

<CIT>, entitled "Closeable, Disposable Wound Care System", discloses a clear receptacle having an adhesive portion for sealing to the patient. The receptacle is a bag for retaining fluids along with a spraying or irrigation member such as a syringe. This enables the wound irrigation procedure to be carried out in a closed system. Upon completion, the receptacle may be completely sealed and disposed of as appropriate to avoid cross-contamination of caregivers.

<CIT>, entitled "Splash and Spill Resistant Extremity Irrigation and Debridement Surgical Drape", seeks to isolate an injured limb creating a self-enclosed system through which irrigation and debridement is performed. The drape isolates the injured limb from the remainder of the body as well as the surgical team in order to create a fluid splash barrier to prevent the splash or spill of contaminated blood or surgical irrigation solutions. Perforated fenestrations provide access for hands of the operator and instruments used.

<CIT>, entitled "Fluid Containment Apparatus", shows a dual-horned upper containment structure wherein pressurized irrigation fluid is supplied to a (homed) inlet and suction supplied to an (homed) outlet, between which fluid circulates within an open lower face of the containment structure and an articulating ring situated atop a bandage that has a cut-out for a wound site (denoted by segments A, Band C). This containment assembly is said to enable pulse lavage irrigation of wounds in a non-controlled setting while providing containment of contaminated irrigation fluid, said to prevent exposure of individuals and surfaces in proximity to the patient to infectious materials.

<CIT>, entitled "Tissue Debriding Apparatus", along with its progeny patents/applications, commonly describe an approach involving plastic enclosure bags used with pulsatile irrigation guns, which is promoted by PulseCare Medical LLC of North Andover, MA ("PulseCare") as Continuous Pulsatile Irrigation ("CPI"). The plastic CPI bag used provides fluid effluent collection and is directed to fostering a dry operating field by creating an arrangement of connected bags. The wound irrigation bag allows for a tent like closed system that keeps the patient and the air, dry from the irrigation process. One or more ports are located so that the proximal side edge may be removed allowing for a pulsatile irrigation gun to be inserted for the irrigation. The caregiver then irrigates <NUM> liters of saline onto the open wound, irrigating, debriding and hydrating the wound surface. The force of the pulsatile irrigator is set at slightly below <NUM> kPa (<NUM> PSI), considered by the United States Food and Drug Administration (FDA) as a safe irrigation force that will not damage wound granulation tissue.

The PulseCare CPI system uses two different bags with a channel that extends from an irrigation bag to a collection reservoir. The plastic thickness is <NUM> MIL for the wound bag and <NUM> MIL for the reservoir bag, which appears adequate for the system. In use, the bags are placed in such a way that gravity drives the effluent from the irrigation bag into the collection bag where flocculating granules are provided that are activated to solidify <NUM> of saline, the collection bag is then folded over and disposed of in the trash or other prescribed medical waste container. This can be done as a biocide is included that kills all biologicals in the irrigated fluid. The system is said to, in some cases, be considered not a "red bag" biological for disposal in any trash dump.

Negative issues include the unit cost of the PulseCare CPI bag, which can retail for $<NUM> (USD) at present and is further supplied non-sterile, and the fact that the CPI bag system requires a custom multi-step manufacturing process, which the instant invention proposes to simplify and improve. The bag requires sealing of all the edges by hand. Then there is placement of the irrigation channels that require double seals to create an open channel. The collection reservoir also requires a double seal for a total of <NUM> double seals. There further remain additional steps of folding and packaging the bags.

It is known in the prior art that the use of a pulsating stream of fluid, such as water, can be utilized to cleanse body tissue of contaminants. <CIT>, entitled "Method and Apparatus for Oral Hygiene", describes a system that creates a fluid jet lavage stream that could cleanse the surgical site. The invention utilizes a piston pump, creating a pulsatile flow measured by stroboscope with a frequency of approximately <NUM> cycles per min, the stroke of the piston being <NUM> (<NUM>/<NUM> inch) and the orifice <NUM> (<NUM> inch in diameter), with a full pressure curve starting at zero pressure and peaking at approximately <NUM> kPa (<NUM> pounds per square inch ("PSI")). This discharge pressure may be carefully controlled by adjusting a bypass channel on the discharge side of the pump down to a level of <NUM> kPa (<NUM> PSI). The wave form of the jet lavage at the beginning of the exhaust stroke of the pump elevates steeply, indicating that there is a shock characteristic. This device was designed for the oral cleaning of teeth, with patients experiencing definite gum pain at higher level of force application.

<CIT>, entitled "Irrigation Handpiece with Built in Pulsing Pump", describes pulsatile irrigation by a mini-piston pump with a battery-powered motor that is housed in a hand-piece that has been sterilized for use in the operative surgical field. This device is self-contained, does not require any connections to a power source or compressed air, and only requires the external connection of the irrigation liquid source. While advocates of pulsed irrigation believe the impact of the liquid droplets have an advantage to dislodge bacteria, disrupt biomass, and remove debris, there is concern of the potential splatter effect and aerosolizing particles that expose the patient and healthcare professionals to air-born contaminants. Documented studies have shown that <NUM>% of the skin and mucous membrane seeding occurs to the eyes, usually resulting from inadequate use of federally mandated eye protection. Contamination of the eye conjunctiva has been well documented with HIV virus and Hepatitis C infections resulting from the splash effect.

<CIT>, entitled "Debridement Extension Providing Irrigation and Mechanical Scrubbing for Removal of Dead, Devitalized, or Contaminated Tissue from a Wound", describes a long gun extension for treating deep tract wounds, such as in orthopedic surgical procedures. The manually actuated gun with tip extension mechanically debrides the wound tissues to be removed, the extension having suction and irrigation ports supplied through a manually actuated gun with pump that pressurizes the irrigation fluid.

<CIT>, entitled "Surgical Instrument, System, and Method for Biofilm Removal", is adapted to dispense pressurized irrigant from an irrigation duct in the instrument through a tip toward a layer of bacterial biofilm. The instrument has an elongated introducer that may be shaped to correspond to the contours of a patient's nasopharyngeal passages and cavities. A controller regulates flow of suction and irrigation to and from the instrument, and may alternatively be operated by a foot pedal by the user of the system. Multiple bags may infuse different fluids which are drawn into the supply tube where a pump situated in a gun pressurizes the fluid and delivers same to a gun actuated manually by a trigger. The instrument functions as an endoscope to visualize accumulations of biofilm, then delivers irrigation fluid under pressure to the biofilm site and aspirates the loosened biofilm through a suction cannula for removal by the instrument.

Two competing suction-lavage products have been designed for use in orthopedic surgery. One branded instrument is the PulsaVac®, manufactured and sold by Zimmer, Inc. ® of Warsaw, Indiana. The other brand, also well-known, is the Interpulse® manufactured and sold by Stryker Instruments® of Kalamazoo, Michigan. Both have enjoyed considerable success over the years.

An alternative irrigation delivery, and a subject of this invention, can be accomplished by the use of a peristaltic pump. The pump is non-sterile and is placed at some distance from the surgical field. However, the tube-set through which irrigation solution passes to the surgical field, is a "closed" sterile system. Two or more rollers advance the fluid by squeezing the tubing against a circumferential rim that contains a segment of the tubing. There may be some form of uncharacteristically uneven flow at low RPMs of the peristaltic pump but at typical RPMs, the flow is virtually direct and continuous.

Historically, the peristaltic pump was patented by Eugene Allen in <NUM> and popularized by Dr. Michael DeBakey in <NUM> when Dr. DeBakey designed a peristaltic pump eventually to be used as a heart-lung machine in cardiac bypass surgery. <CIT>, entitled "Peristaltic Irrigation Pump System", is representative of an irrigation and distension pump system for surgical use. Numerous system designs are said to be known by which the tubing used with the pumps may be configured into surgical tube sets adapted for various applications (arthroscopy, laparoscopy, irrigation, etc.). The tube sets may be coded to identify the procedure for which they are designed and can be relatively easily engaged with the pump and other components. These designs may generally utilize a cassette in the form of a molded housing which retains a portion of the tubing so that the engagement of the tubing with the peristaltic pump simply requires the attachment of the cassette adjacent the peristaltic pump roller assembly rather than the laborious process of threading a tube around the roller assembly and securing it in place.

While there are many applications to these peristaltic pumps, study of the fluid mechanics reveal that certain parameters can be optimized for use in clinical practice. The use of peristaltic pumps in wound debridement is not well-elucidated concerning how these systems function. That is, pump head pressure, flow rate, and flow velocity have not been categorized for clinical efficacy and safety. The important difference from a piston pump is the fact that the peristaltic pump flow rate is constant and the pressure is determined by the RPM's. This control determines the force generated by the system. As the pump RPM's increase, the flow rate increases, and the pressure of the system increases. As compared to the piston pump, where the pressure becomes the variable while flow remains constant for a given RPM. As understood by practice of the present invention, with the Bernoulli Effect, the inner tube dimensional area determines the velocity at the tip. This function has value if there is a reason to deliver different fluids at differing flow rates. This discussion will be continued below, in conjunction with the choice of parameters taught by the practice of the subject invention.

The afore-mentioned approaches of others generally have not transcended the problems inherent in conventionally-used pulsatile irrigation methods, nor have these sought to employ peristaltic pumps.

The afore-mentioned approaches of others, using pulsatile pumps, insufficiently address the provision of a continuous flow of an irrigation solution to an irrigation instrument, and the opportunities for improvement using other means of wound irrigation, apart from pulsatile pumps.

These approaches of others have not reduced splatter by the pulsatile delivery system, in the operating field.

The approaches of others in attempting to contain the pulsatile irrigation splatter by means of enclosing the wound site have not resulted in a simple, economical and effective containment, during the delivery of wound irrigation solution.

There is a need for a continuous, peristaltic irrigation device and a systemfor outpatient wound debridement, irrigation and removal of biofilm.

An advantage of the present invention is that a completely sterile device enters the sterile surgical field. A fluid-isolating peristaltic pump operated by a foot pedal of the invention remotely transports a sterile irrigation solution that remain from outside the sterile operating field into the wound site where only the tubing of the pump and effluent are disposed of after a single use.

Another advantage of the present invention is a pump that can quickly and smoothly deliver a continuous flow of irrigation solution in an optimal, i.e., flat spray onto the wound site, without aerosolized biofilm spattering as experienced with hand actuated guns driven by pulsatile pumps that must be disposed of after a single use.

Yet another advantage of the present invention is an inexpensive tube set that is driven by a durable pump and foot pedal control shown to be reusable for a lengthy life cycle with a multitude of reliable operations.

Still another advantage of the present invention is a biofilm removal in the effluent generated by the procedure, according to the invention, rather than entrained biofilm arising from the wound site into the air.

The features and advantages of the disclosure will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the disclosure without undue experimentation. The features and advantages of the disclosure may be realized and obtained by means of the devices and combinations particularly pointed out in the appended claims.

Aspects of the invention are disclosed in the following description and related drawings directed to specific embodiments of the invention. Alternate embodiments may be devised without departing from the scope of the invention. Additionally, well-known elements of exemplary embodiments of the invention will not be described in detail or will be omitted so as not to obscure the relevant details of the invention. Further, to facilitate an understanding of the description discussion of several terms used herein follows.

Likewise, any of the terms "embodiments of the invention", "embodiment" or "invention" does not require that all embodiments of the invention include the discussed feature, advantage or mode of operation.

Embodiments can be designed as taught herein, to cooperate with nearly any elements that make use of a peristaltic pump and tube set for wound irrigation. For examples, embodiments can be designed to cooperate with various styles and shapes of the present device, assembly and system as will be appreciated by those having ordinary skill in the art.

Nevertheless, for illustrative purpose and in a non-limiting fashion, at least one exemplary embodiment is described herein in reference to the device nozzle. At least another embodiment that is an alternative to the immediately preceding device nozzle is provided. Yet another alternative embodiment thereto is further provided.

According to one aspect of the present invention, there is generally shown in <FIG><NUM> and <FIG>, a medical device <NUM>, for debridement and irrigation of a patient wound site <NUM>. Device <NUM> contains a tube <NUM> having a proximal portion <NUM> adapted to receive an irrigation solution <NUM> from a reservoir generally indicated at <NUM>, a distal portion <NUM> of tube <NUM> having a distinctive nozzle <NUM> and an intermediate portion <NUM> for transporting the solution. Tube <NUM> has a barrel <NUM> that may be manipulated by a user <NUM> (shown snipping open an entry slit for the device in <FIG>) to position device <NUM> relative to wound site <NUM>. Nozzle <NUM> has a body <NUM> formed with a distally leading channel <NUM> presenting a semispherical first spatial conformation <NUM> and a proximally leading opening formed in the body presenting a second spatial conformation <NUM> intersecting the semispherical terminus <NUM> at a V-notch <NUM> (<FIG>). This geometry, as will be derived from principles of flow mechanics discussed below, defines what will be described as an "effective diameter" of the nozzle. It is this numerical value, i.e., range of values, which determines a corresponding spray pattern and other flow characteristics, from nozzle <NUM> onto wound <NUM>.

Several preferred embodiments of device <NUM> will now be described, in relation to assembling of various arrangements of its features. Nozzle <NUM> is also preferably in a fixed position on a distal tip or portion <NUM> of tube <NUM>, which is also preferably captured within a hand piece generally shown at <NUM> in its alternative forms (<FIG> and <NUM>) that simultaneously prevents rotation of tube <NUM> relative to the hand piece, more preferably the hand piece is affixed to barrel <NUM>, preventing relative motion therebetween. Device <NUM> may preferably have a hand piece <NUM> formed with an integral finger grip <NUM> consisting of lateral halves <NUM> held together by pins or the like <NUM> (<FIG>) affixed to barrel <NUM>, preventing relative motion therebetween. Alternatively, hand piece <NUM> is plastic and elongated with a bulbous molded shape indicated at <NUM>, capturing tube <NUM> and nozzle <NUM> at a distal tip <NUM> of the tube, preventing relative motion therebetween. It is also preferred that hand piece <NUM> structurally captures nozzle <NUM> at distal tip <NUM>, including complementary anti-rotation structures (not shown) preventing relative motion therebetween. Alternatively, hand piece <NUM> captures nozzle <NUM> at distal tip <NUM>, the nozzle being made of injection molded plastic and alternatively bonded to the tip and hand piece, respectively, by an adhesive or by sonic welding (not shown), preventing relative motion therebetween. Nozzle <NUM> may alternatively be a metallic material such as brass or stainless steel and mechanically fastened to hand piece <NUM> at distal tip <NUM>, using a threaded <NUM> or crimped (not shown) fastener that aligns channel <NUM> with the internal diameter (Arrows <NUM>) of distal tip <NUM>. A vent hole <NUM> is formed in hand piece <NUM> and barrel <NUM>, to allow manual regulation of the flow of irrigation solution <NUM> by user <NUM>.

Various preferred configurations of nozzle <NUM> will now be described. Device <NUM> preferably includes nozzle <NUM> having its proximally leading opening formed with a spatial geometry selected from a wedge shape as shown, a cone shape (discussed but not shown), a tetrahedron or a star shape (not shown) formation <NUM> in body <NUM>. Nozzle <NUM> more preferably has a proximally leading generally wedge shaped formation <NUM> (<FIG>and <FIG>Body <NUM> presents an apical spatial portion <NUM> such as V-notch <NUM> that intersects with the semispherical terminus <NUM> of channel <NUM>. Although not specifically shown in the Figures, it is alternatively preferred that the nozzle has a proximally leading generally conically shaped formation in the body, the cone presenting an apical spatial conformation that intersects with the semispherical terminus of the channel, similarly to what has been illustrated and discussed with respect to the V-notch of the wedge-shaped embodiment elucidated above. Nozzle <NUM> may be constructed of an injection-molded plastic material such as PVC or the like, depending on cost and design for moldability, whereas tube <NUM> is made of an extruded plastic material, also possibly PVC. Although not shown in the Figures, the tube may be extruded with a polygonal cross-section and the handpiece and nozzle injection molded with complementary polygonal cross-sections, respectively, which together in the proper manner would prevent relative motion therebetween.

Various preferred performance attributes will now be discussed. The desired spray pattern, determined by the effective diameter of nozzle <NUM>, is a flattened pattern generally approaching perpendicularity to the axis of channel <NUM>, which corresponds to the profile and proportions of a wound <NUM> typical of that shown, (<FIG><FIG><FIG><FIG>The angle of incidence <NUM> of the generally flat spray pattern relative to the axis <NUM> (<FIG>) of channel <NUM> (<FIG>) is preferably greater than zero but less than about <NUM> degrees. Alternatively, an angle of incidence <NUM> of the spray pattern relative to the axis of channel <NUM>, as determined by the effective diameter, may be generally arrow-shaped greater than about <NUM> degrees and less than about <NUM> degrees. Alternatively preferred, the shape and angle of incidence <NUM> of the spray pattern relative to the axis of channel <NUM>, as determined by the effective diameter of nozzle <NUM> may generally be conical and between about <NUM> degrees and about <NUM> degrees. The two ranges of more acute angles of incidence are not shown, nor is the conical profile formed in the body, though the same are described below as possible embodiments of the present invention, depending on the performance objectives.

According to a second aspect of the present invention, a wound irrigation assembly <NUM> is described. Included is device <NUM> with tube <NUM> having inlet <NUM> for connection with reservoir <NUM> of irrigation solution <NUM> and an outlet via distal tip <NUM>. Hand piece <NUM> captures barrel <NUM>. Nozzle <NUM> is aligned with inner diameter <NUM> of tube outlet <NUM> and is captured by hand piece <NUM>, preventing relative motion therebetween. Also included in assembly <NUM> is a clear plastic containment and collection bag shown with two variations, i.e., a torso wound version <NUM> and an extremity wound version <NUM>. Bags <NUM>, <NUM> are made of a generally tubular sheet stock unrolled (Arrow <NUM>) from a spool <NUM> (<FIG>that includes a lower patient-side layer <NUM> and an upper device receiving layer <NUM>. Patient-side layer <NUM> has a fenestration <NUM> sized to accommodate wound <NUM> and a dual sided adhesive tape <NUM> with one side <NUM> adhered on the patient side layer along an outer border of the fenestration. Tape <NUM> forms a polygonal (<FIG>) or rounded (<FIG>) lateral flow barrier <NUM> when an opposite side <NUM> of the tape is adhered to a patient's body <NUM> in alignment with wound <NUM>. Upper side <NUM> of bags <NUM>, <NUM> allows for a random access point chosen by the user to be snipped in a bag with scissors <NUM> through which nozzle <NUM> passes thereby transporting sterile solution <NUM> into a sterile operating field <NUM> delimited within the given bag. In <FIG>, an ovoid tape dam <NUM> is shown with extremity bag <NUM> having an open end <NUM> for insertion of the bodily extremity as shown in <FIG>, The open end <NUM> is provided with double-sided tape <NUM> and may also be provided with elasticized gathers made of hook and loop material (Velcro®) as shown in <FIG>. Nozzle <NUM> has body <NUM> formed with a distally leading channel <NUM> presenting a semispherical first spatial conformation <NUM> and a proximally leading opening <NUM> formed in the body presenting a second spatial conformation <NUM> intersecting the semispherical terminus. This relationship defines an effective diameter of nozzle <NUM> that determines a corresponding spray pattern onto wound <NUM>.

The peristaltic pump <NUM> in the present irrigation system has a key feature, which is the spray pattern created by the tip of the spray nozzle <NUM>, shown by the several illustrated embodiments of the invention. This system utilizes a direct continuous flow of irrigating fluid that is directed under low pressure (less than15 PSI) to the surface of wound <NUM> for debridement and removal of detritus. The pump <NUM> is used in conjunction with a tube set including an inlet portion <NUM> and an outlet portion <NUM>. This differs from the pulsatile irrigator
system discussed previously, i.e., where a mini-piston pump creates a power stroke accelerating the flow to a peak pressure of fluid flow achieving the same pressure level (less than <NUM> PSI). The principle characteristic of the pulsatile pump flow is the 'splash' effect created when the fluid is expelled from the tip (not shown). Altering the tip dimension may change the pulsatile flow, but the explosive discharge at peak pressure creates an aerosolized spray that entrains disrupted biofilm where it presents a health hazard to caregivers and patients.

An important determination of the peristaltic irrigation result is exactly what the nozzle spray looks like. Options may include a fan shape of various angles, a cone shape, or a four-square shape. Following the diagram of a fan shaped spray nozzle in <FIG>, there are two key elements that determine the spray fflow. First is the semispherical hole <NUM> that extends from the inlet <NUM> to the nozzle tip. The distance of the dome <NUM> of the hemisphere to the tip surface can influence the fan spray by determining the width of the spray pattern. The closer the dome <NUM> is to the surface, the wider the "V" notch <NUM> may be, and this allows for a wider spray pattern. As the dome <NUM> moves away from the tip, the "V" notch narrows, (not shown) which will narrow the spray pattern. Although not shown, similar effects can occur with a cone spray, where a cone is drilled from the tip down to the semisphere. The "V" notch can be made as an axial plane cut in the distal tip surface that exactly centers on the semisphere surface (not shown). The limbs of the "V" cut can be wider or narrower. To create a 'four square' spray pattern, a second "V" shaped cut can be made that centers on the semisphere and is perpendicular to the first cut (not shown). One may consult the well-known Bete Catalog, at Page <NUM>, standard flat spray nozzle; NF10- <NUM>/<NUM>" NPT; <NUM> PSI; Max Flow <NUM> GPM; Equivalent Tip Orifice Diameter-<NUM>" Spray Angles <NUM>°, <NUM>°; Available Materials are brass, <NUM> Stainless Steel, <NUM> Stainless steel, and PVC (plastic).

The other important consideration is the flow rate of the peristaltic pump <NUM> that approximates the maximum pressure allowed (<NUM> PSI) when the RPM of the pump reaches the maximum. As the subtle differences in the creation of the nozzle spray <NUM> are unique to the material machining or molding process, the surface area of the hole <NUM> in the nozzle tip <NUM> determines the pressure at a given rate of flow. Therefore, the system design must work backward from the chosen pressure limit, the maximum flow rate determined by the peristaltic pump <NUM> at a given RPM, and the final tip area.

In <FIG>, there is disclosed a system for creating a digital signal to regulate the speed of a peristaltic pump operated by a foot pedal <NUM>. The system includes the step of counting ticks in an encoder using an optical or electrical signal and the step of inputting the signal to the system. A further step is converting the signal input to a digital scale from <NUM> to <NUM>, either through an analog to digital converter <NUM> or a counting microprocessor. A stepper motor <NUM> is provided and the digital scale is used to alter the time step between cycles of the stepper motor. Phases of the stepper motor <NUM> are alternated. The lag between each charge of the phase by the digital signal is modulated. The time delay <NUM> is changed by dividing the minimum delay over the scaled input signal <NUM> for a Minimum Delay/Input Signal. As the input signal is reduced from <NUM> to <NUM>, the motor reduces speed <NUM>.

<FIG> shows a basic wiring diagram for the various electrically controlled components of the foot pedal <NUM> control systems, which the reader should find self-explanatory from the descriptive labels accompanying the component setup.

<FIG> shows one optional analog pedal <NUM> control set-up where the change in resistance <NUM> rotates or translates a potentiometer to affect the pump speed.

The bags <NUM>, <NUM> of assembly <NUM> preferably contain a biocidal flocculent material <NUM> that solidifies effluent <NUM> within the bag <NUM>, <NUM> for easier collection and disposal. Bags <NUM>, <NUM> of assembly <NUM> preferably define a rectangular shape, being sealed at the longitudinal creases <NUM> on the opposed longitudinal sides (i.e., in the spooling direction) and cut and impact-sealed (Arrow <NUM>) at the ends <NUM> of the bag blank. This configuration ideally accommodates a torso wound irrigation procedure, the fenestration <NUM> being formed intermediate the longitudinal creases <NUM> and ends (hatched lines) of the bag <NUM> to be adhered by the tape dam <NUM> to the patient's body <NUM>. Alternatively, the bag <NUM> is cut and sealed (by action of lever as shown) on only one of the ends opposite the open end <NUM> so that three sides of the rectangular bag blank are closed. There is thus an opening <NUM> at the one end to allow ingress of an upper or lower bodily extremity <NUM> for irrigation of a wound <NUM> thereon. The open side <NUM> is secured by tape and/or gathers <NUM> around the extremity <NUM> to prevent disengagement of the bag <NUM> prior to completion of the procedure. The tape dam <NUM> constrains lateral flow of effluent <NUM> within the bag for collection and disposal, similar to the design of torso bag <NUM>, The nozzle <NUM> of assembly <NUM> has an alternately preferred proximally leading generally wedge shaped formation <NUM> in the body <NUM> and presents an apical spatial portion that intersects with the semispherical terminus <NUM> of channel <NUM> to determine the spray pattern <NUM>. Alternatively, though not specifically shown in the Figures, the assembly nozzle may have a proximally leading generally conically shaped formation in the body, the cone presenting an apical spatial conformation that intersects with the semispherical terminus of the channel. The assembly nozzle preferably has an effective diameter that determines a generally flat spray pattern <NUM> coinciding with a profile of the wound <NUM>.

According to a third aspect of the present invention, a system for debridement and irrigation of an outpatient wound <NUM> will now be described. Device <NUM> includes tube <NUM> having inlet <NUM> and outlet tip <NUM> with barrel <NUM> therebetween and an elongated hand piece <NUM> with lobes <NUM> mounted in fixed position around the barrel. Nozzle <NUM> is mounted at a distal portion <NUM> of tube <NUM> and hand piece <NUM> without relative motion between the nozzle, tube and hand piece, respectively. A generally rectangular clear plastic tubular containment and collection bag having at least three (<NUM>) and up to all four (<NUM>) sides of the bag periphery is sealed as described above relative to assembly <NUM>. Fenestration <NUM> is formed in the lower patient side <NUM> of the bag bordered by a dual-sided tape dam <NUM> which, when adhered also to the patient <NUM>, confines lateral flow of effluent <NUM> to the space within the bag for collection of the effluent and disposal of the bag. The fenestration <NUM> and corresponding tape dam <NUM> profiles are selected from generally rounded or polygonal shapes (<FIG>), depending upon a given wound site <NUM>.

Referring to <FIG>, there is further shown a device <NUM> with delivery tube <NUM> enclosed tightly by preferred plastic hand piece <NUM> with bulbous grip <NUM> of the present invention. Various cooperating fastening members will now be described that are molded within the hand piece for snapping the mating halves thereof together to securely capture tube <NUM> against relative motion with hand piece <NUM>. Particularly, <FIG> are a series of orthogonal external views of the device <NUM>, illustrating the ergonomic hand piece <NUM>. Common structures are indicated by nozzle <NUM> and V-notch <NUM>, vent hole <NUM>, and an elongated downwardly tapering neck <NUM>. <FIG> shows a barb <NUM> of the proximal nozzle interlocking with distal end <NUM> of neck <NUM>. <FIG> shows the fully captured length of tube <NUM> with internal diameter aligned with the bore of nozzle leading into channel <NUM> with semispherical terminus <NUM> spaced from V-notch <NUM>, as hereinbefore described. The adjoining structures of hand piece <NUM> are shown relative to passage of tube <NUM>. <FIG> shows the mating halves of preferred bulbous hand piece <NUM> snapped together via locking tangs <NUM>, also showing visible mold part lines leading from neck <NUM> to nozzle <NUM>. <FIG> are cut away to further reveal locking tangs <NUM>, tube <NUM> retaining ribs <NUM> and seats <NUM> to receive pegs <NUM> from <FIG> and mating peripheral alignment grooves <NUM> on both molded halves. A serrated groove <NUM> on proximal barb <NUM> is seated at <NUM> in <FIG>. <FIG> shows in exploded form the mating halves of the hand piece <NUM> of device <NUM>. The internal snap-in structures are shown in corresponding relationship to one another on the opposed molded halves, as detailed above in connection with <FIG>.

The system preferably includes a sterile packet with a disposable wipe (not shown) containing an antiseptic such as Chlorhexidine Gluconate ("CHG") or the like in terms of safety and efficacy. Another alternative antiseptic is Hypochlorous Acid that has shown effective bacterial biofilm control, however, the regulatory approval of the antiseptic remains in progress relative to wound irrigation. Hypochlorous Acid, in an optical dosage form, is currently available in OTC products.

Importantly, the device, assembly and system aspects of the present invention, described above, utilize a peristaltic pump <NUM> fitted with a tube set (<NUM>, <NUM>) which is supplied with irrigation solution <NUM> from a reservoir<NUM>. To calculate pump pressure in a peristaltic pump system, one needs to know the basic flow velocity and the inner diameter of the pump tubing. Using Bernoulli's formula, the pressure of the system can be determined for comparison:
<MAT>
Bernoulli formula with ρ as the gonstant of <NUM>/m<NUM>
<MAT>
Volumetric flow rate from flow velocity times area of tube inner diameter<MAT>
Area of tube inner diameter
<MAT>
Substitution of Volumetric flow
<MAT>
Substitution of Area.

The pump delivers a flow rate between about <NUM> milliliters per minute to about <NUM> milliliters per minute at a constant pressure of <NUM> PSI, wherein the effective diameter of the nozzle <NUM> is between about <NUM> millimeters and <NUM> millimeters, and further wherein an effective diameter of <NUM> millimeters creates a distal tip flow pressure of <NUM> PSI for an optimal flow rate of <NUM> milliliters per minute. This results in a three liter reservoir <NUM> of irrigation solution <NUM> being drained in merely a few minutes. To calculate the optimal distal tubing <NUM> inner diameter that would render <NUM> PSI of fluid pressure with the above peristaltic pump that has a maximum setting of <NUM> RPM's with a flow rate measured at <NUM> milliliters per minute one may use the following formula. <MAT>
Where V̇ = <NUM>/min = <NUM><NUM>/sec
<MAT>
P for <NUM> PSI = <NUM>,<NUM>/meter sec<NUM> (Pascals)
<MAT>
<MAT>.

The other factor to be weighed is the splatter effect magnified by the pulsatile flow of prior devices of this type. Again, the pressure of the piston pump is constant causing the same splatter effect even at lower RPMs The uneven flow effect is minimally seen in the peristaltic pumps at rather low BPM and disappears at higher PPM, As fluid is incompressible, the pressure drops very slightly with the wave. drawing fluid behind the fluid roller, This allows for a steady continuous stream flow of fluid froin the distal tip of the device which some believe is more effective at removing biomass compared to a pulsed stream.

The advantages for the peristaltic pump <NUM> include the fact that the pump becomes a durable item that may be reused many times with standard maintenance. This will lower the costs. The piston pump loses sterility and must be disposed of after a single use because of potential biomass contamination. The operator has control of the pressure with the peristaltic pump <NUM> being gentler at lower RPM and more brisk and stiff at higher RPM of the pump. This can be done with a manual dial or an electrically activated variable output foot pedal <NUM> that controls the RPM, as discussed relative to <FIG> and <FIG>-14B above.

Peristaltic pumps made by Prefluid Ltd of Changzhou, China have been found acceptable herein, particularly Model MP <NUM>-TH162 having a flow rate range from. <NUM>-<NUM>/min. Specifications for the MP <NUM> line of pumps were accessed on November <NUM>, <NUM> at www. net/medical-peristaltic-pump/MP300-peristaltic-pump. Likewise, the Prefluid MP <NUM> line of peristaltic pumps was also found acceptable for certain uses. The flow rate of these MP <NUM> pumps is in the range of <NUM>-<NUM>/min and detailed specifications for this pump line were accessed on Mov. <NUM>, <NUM> at www. net/medical-peristaltic-pump/MP200-peristaltic-pump. These MP <NUM> and MP <NUM> pumps are said by the manufacturer to be applicable to hospital surgical debridement.

The peristaltic pump <NUM> in the present irrigation system <NUM> has several key features that have the following characteristics. Pump <NUM> has a variable flow rate determined by the operator which allows for the administration of different irrigation effluents Normal saline or water may be irrigated at the maximum pressure allowed by the maximal flow, but antiseptic solutions such as <NUM>% chlorhexidine gluconate (Irrisept®) in irrigation should be applied at very low pressures that allow the irrigation solution <NUM> to pool in the wound <NUM>. A unique feature of the pump system <NUM> is to have two separate irrigation fluids <NUM>, <NUM> attached to the proximal tube irrigation channel that may be administered a different desired pressures, but still a part of the same assembly (<FIG>, <FIG><FIG>showing two bags <NUM>, <NUM> that have different fluids <NUM>, <NUM>. Another key feature is the spray pattern created by the tip of the spray nozzle <NUM> shown by several illustrated embodiments of the invention (<FIG><FIG><FIG><FIG>This system utilizes a direct continuous flow of irrigating fluid that is directed under low pressure (less than <NUM> PSI) to the surface of the wound <NUM> for debridement and removal of detritus. Empirical considerations suggest that the direct continuous flow with the fluid directed at an angle to the surface may be more effective than a flow directed perpendicular to the surface. The pump <NUM> is used in conjunction with a tube set <NUM>, 23A-C including an inlet portion 23A and an outlet portion <NUM>.

Claim 1:
A medical device (<NUM>) for irrigation of a wound site (<NUM>), comprising:
a hand piece (<NUM>); and
a tube (<NUM>) having a proximal portion (<NUM>) adapted to receive an irrigation solution (<NUM>), a distal tip (<NUM>) having a nozzle (<NUM>) and an intermediate portion for transporting the solution (<NUM>), the tube (<NUM>) having a manipulable barrel (<NUM>) to position the device (<NUM>) relative to the wound site (<NUM>), wherein the nozzle (<NUM>) has a body (<NUM>) formed with a distally leading channel (<NUM>) presenting a semispherical first spatial conformation (<NUM>) and a proximally leading opening (<NUM>) formed in the body (<NUM>) presenting a second spatial conformation (<NUM>) intersecting the semispherical terminus, defining an effective diameter of the nozzle (<NUM>) that determines a corresponding spray pattern from the nozzle (<NUM>) onto the wound (<NUM>);
wherein the hand piece (<NUM>) captures the nozzle (<NUM>) at the distal tip (<NUM>) of the tube (<NUM>), including complementary anti-rotation structures preventing relative motion therebetween.