Microbial decontamination.

Background of the Invention

The present invention pertains to the art of microbial decontamination. It finds particular application in conjunction with sterilizing medical equipment and will be described with particular reference thereto. It will be appreciated, however, that the invention is also applicable to disinfecting systems as well as to microbially decontaminating a wide range of items, including dental instruments, endoscopes, laboratory equipment, manufacturing equipment, and other equipment and items on which it is desirable to eliminate microbial life forms.

Sterilization connotes the absence of all life forms, including bacterial endospores which are the living organisms most resistant to conventional sterilants. Disinfection, by distinction, only connotes the absence of pathogenic life forms. Microbial decontamination is generic to both sterilization and disinfection.

Most medical equipment is sterilized at high temperatures. Commonly, the equipment is sterilized in a steam autoclave under a combination of high temperature and pressure. Endoscopes, rubber and plastic devices or portions of devices, such as lenses, and the like may be destroyed or have their useful lives severely curtailed by this heat and pressure.

The more sensitive medical equipment is often sterilized with ethylene oxide, which is thermally less severe than steam. The items must be exposed to the ethylene oxide for a relatively long time, on the order of three and a half hours. Thereafter, eight to twelve hours are normally required for de-gassing or desorbing the ethylene oxide from plastic and other materials which are capable of absorbing the ethylene oxide. The pressurization and depressurization cycles of ethylene oxide sterilization may damage lens systems and other delicate instruments. Moreover, the ethylene oxide is relatively expensive. It is sufficiently toxic and volatile that extensive precautions are commonly taken to assure operator safety.

Liquid systems are commonly used for disinfection of heat sensitive or other delicate instruments. Using liquid sterilants to achieve disinfection is normally rapid, cost effective, and does minimal damage to medical devices. Commonly, a technician mixes a sterilant composition and manually immerses the item to be sterilized. The immersion is timed manually by the technician. Technician variation, liquid sterilant shelf life, and the like raise problems with assurance and reproducibility of the disinfection. Rinsing of the items to remove chemical residues also adds a variable that reduces the assurance of disinfection or sterility. Once the sterilant solution is rinsed, the item is susceptible to reinfection by air borne microbes.

In accordance with the present invention, a new and improved sterilization apparatus, system, and method are provided which overcomes the above referenced problems and others.

Summary of the Invention

In accordance with one aspect of the present invention, a liquid sterilizing or disinfecting system is provided. A sloping container-receiving basin contains a vent aperture adjacent an upper most end, a drain aperture adjacent a lower most end, and a liquid inlet. A lid selectively seals the basin when in a closed position and opens to provide ready access to the basin. A container (B) for receiving articles to be microbially decontaminated is removably disposed in the basin. A liquid sterilant supply means supplies a liquid antimicrobial solution and a sterile rinse supply means supplies a sterile rinse liquid. A drain is connected with the basin drain aperture for draining antimicrobial and rinse liquids from the basin. A means is provided for selectively opening and closing the drain to drain liquids from the basin and retain liquids in the basin. A pump selectively pumps volumes of liquid antimicrobial solution from the liquid antimicrobial solution supply means and volumes of sterile rinse liquid from the rinse supply means to the liquid inlet for filling the container and displacing the air therefrom.

In accordance with another aspect of the invention, the container includes an outer lower shell having a bottom surface and a peripheral wall. The shell defines a drain aperture adjacent to the basin lower most portion and defines a liquid receiving aperture in fluid communication with the basin liquid inlet. A nozzle plate defines a tortuous inlet path from the liquid receiving aperture to a plurality of nozzles distributed around the lower shell. The inlet path is sufficiently tortuous that migration of contaminating microbes in ambient air after removal from the basin is inhibited. A container cover has a top surface and downward depending flanges which engage the shell to close the container. At least one of the shell and cover is configured to define a tortuous vent path from at least an upper most portion of the container when disposed in the basin such that received liquids displace substantially all air from the container through the vent path.

One advantage of the present invention is that it facilitates effective sterilization of medical and other items with liquid sterilants.

Another advantage of the present invention is that it maintains the sterile condition of the items during temporary or longer term storage.

Yet another advantage of the present invention is that it facilitates maintaining an organized inventory of sterilized items.

Still further advantages of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description.

Brief Description of the Drawings

The invention may take form in various parts and arrangements of parts. The drawings are only for purposes of illustrating a preferred embodiment and are not to be construed as limiting the invention. <ul id="ul0001" list-style="none"><li>FIGURE 1 is a perspective view of a microbial decontamination system in accordance with the present invention;</li><li>FIGURE 2 is a diagrammatic illustration of the fluid flow paths for the system of FIGURE 1;</li><li>FIGURE 3 is a top view of the container, particularly the container cover;</li><li>FIGURE 4 is a side view of the cover;</li><li>FIGURE 5 is a top view of the container lower shell with the cover removed; and,</li><li>FIGURE 6 is a side view of the shell of FIGURE 5.</li></ul>

Detailed Description of the Preferred Embodiment

With reference to FIGURE 1, a sterilizing apparatus <b>A</b> defines a basin <b>10</b> for removably receiving one of a plurality of containers <b>B</b>. Each container may be configured or fitted with appropriate mounting structures <b>C</b> for holding or arranging medical instruments or other items. After the container is placed in the basin, a lid <b>12</b> is closed causing a gasket <b>14</b> to seal the basin and container from the ambient atmosphere. The sterilizing apparatus in a carefully controlled cycle floods the basin filling the container and surrounding the medical instruments, container, or other items to be sterilized with a liquid sterilant or other antimicrobial solution. The sterilant solution is drained and a sterile rinse fills the basin and container to remove chemical residue. After the rinse has been drained, the lid is opened and the container is removed as a unit containing sterilized items. The container is configured such that it permits the ingress and egress of liquid sterilant and rinse solutions but prevents microbial contamination in the ambient air from reaching the enclosed medical instruments or other items. The container with the contained sterilized items may be inventoried and stored until the sterile items are needed.

With reference to FIGURE 2, water, such as tap water, is received at an inlet <b>20</b>. A valve <b>22</b> selectively enables the water to flow to a sterilizing means <b>24</b> for sterilizing the received water. In the preferred embodiment, the sterilizing means is a filter which mechanically separates microbes and other contaminants from the received water. When the valve <b>22</b> is opened, incoming water flows through the filter <b>24</b> becoming sterilized and flows through a tubing system <b>26</b> to a basin inlet <b>28</b>. A seal <b>30</b> directs water into a liquid receiving inlet <b>32</b> in a lower wall <b>34</b> of the container <b>B</b>.

The liquid flows through a tortuous path <b>40</b> defined between the bottom wall <b>34</b> and apertures <b>42</b> in a baffle plate <b>44</b> of the container. The liquid flows into the interior of the container immersing the items to be sterilized. Liquid flows out of the container through a container drain outlet <b>46</b> and vent passage <b>48</b> and the tubing system <b>26</b> conveys the fluid from a basin drain outlet <b>50</b> to a heater <b>52</b> and a pump <b>54</b>. A drain valve <b>56</b> selectively enables the fluid to be drained from the system. A recirculating valve <b>58</b> allows the pump to pump the fluid through the tubing system back to the fluid inlet <b>28</b>. As additional sterile water flows into the system, air is displaced through a vent passage or vent outlet <b>60</b> which is connected by a check valve <b>62</b> with the drain.

The received liquid also fills a well <b>70</b> which defines a reagent receiving chamber for receiving antimicrobial agents, wetting agents, detergents, and other treatment chemicals for improving the cleaning and sterilizing effect. An ampule <b>72</b> contains peracetic acid or other strong oxidant compositions or reagents which react to form strong oxidants, as well as buffers and corrosion inhibitors to be introduced into the well. After the system is filled with water, inlet valve <b>22</b> is closed. The recirculating valve <b>58</b> is opened and the pump <b>54</b> is actuated. As fluid is drawn through the well by the pump, the reagents mix with the water forming a sterilizing or other antimicrobial solution. The sterilizing solution is circulated through the tubing system <b>26</b> back to the inlet <b>28</b> through the tortuous path <b>40</b> and distributed among the many inlets of the baffle plate <b>44</b>. As the pump <b>54</b> circulates the sterilant solution, some of the sterilant flows through the sterilizing filter <b>24</b> sterilizing it. Other solution flows through the vent <b>60</b> and other tubing and fluid contacting surfaces.

After the sterilant solution has been maintained in contact with the items in the container and all tubing valve and other surfaces between the sterilizing means <b>24</b> for a selected duration, the recirculation valve <b>58</b> is closed and the drain valve <b>56</b> is opened. The anti-microbial solution is pumped or drained from the system. In this manner, all the tubing and valve surfaces with which the sterile rinse fluid comes in contact are sterilized by the sterilant solution. More specifically, the fill valve <b>20</b> is again opened so that tap water flows through filter <b>24</b> through the sterilized tubing system <b>26</b> to the fluid inlet <b>28</b>. The sterile rinse solution continues to flow into the basin <b>10</b> until all the air is displaced. Pump <b>54</b> may be actuated again to recirculate the rinse solution for a preselected duration. Thereafter, the drain valve <b>56</b> is opened and the rinse solution is drained. Air flows through a check valve <b>76</b> and the sterilizing filter <b>74</b> such that sterile air fills the basin and container as the rinse and sterilant solutions are drained.

With reference to FIGURES 3 and 4, the container <b>B</b> has a generally flat cover <b>80</b> with a downward depending peripheral wall <b>82</b> extending peripherally therearound. Spacers <b>84</b> extend upward from the container cover to engage the sterilizer lid such that lid urges the container into firm engagement with the sealing means <b>28</b>. The spacers are configured such that no air is trapped by the spacers or the interaction between the spacers and the sterilizer lid. Rather, all surfaces around the spacers become immersed in the sterilant solution and are sterilized.

With reference to FIGURE 5, the container bottom wall <b>34</b> encloses the bottom of the container. The container bottom wall connects with a container peripheral wall <b>86</b> which extends peripherally around the container bottom wall. Projections <b>87</b> (Figure 3) define a horizontal vent path portion over the container upper lip and projections <b>88</b> define a vertical vent path portion along the side of the container so that the sterilant and rinse liquids can displace the ambient air. Moreover, the container and cover peripheral walls define the horizontal and vertical portions of the vent path <b>48</b> sufficiently tortuously that air born microbes are not carried into the container interior through the vent path.

The baffle plate <b>44</b> has a plurality of apertures <b>90</b> distributed therearound. The apertures are disposed offset from the inlet aperture <b>28</b>. In this manner, the tortuous path <b>40</b> which is defined between the inlet aperture and the baffle plate nozzle apertures is sufficiently tortuous that air borne microbes are inhibited from entering the container. The baffle plate includes a plurality of projections <b>92</b> which project downward toward the container bottom wall to maintain the baffle plate and the container in the spaced relationship. The baffle plate also defines a canted surface section <b>94</b> adjacent the drain outlet. The canted surface portion extends over the drain outlet and provides fluid flow paths towards either edge thereof. Preferably, the canted portion is symmetrically disposed over the outlet aperture <b>46</b>. Liquid then flows to the edges of the canted portion onto the lower surface <b>34</b> and down to the drain aperture <b>46</b>. In this manner, a tortuous path is again defined between the drain aperture and the interior of the container. Projections <b>96</b> provide a barrier between the inlet and outlet passages so that the liquid pumped into the inlet flows through the baffle plate nozzle apertures primarily rather than directly to the outlet. A small vent passage <b>98</b> is defined through the barrier to assure that no ambient air is trapped adjacent the vent outlet and to thoroughly drain the baffle interspace during draining cycles. When the pump <b>54</b> is activated, some liquid will, of course, flow through this barrier vent but the majority will be discharged through the baffle plate apertures <b>90</b>.

A pair of handles <b>100</b> are interconnected with the container lower portion to facilitate lifting of the container without accidental removal of the container cover.

The invention has been described with reference to the preferred embodiment. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. For example, the bottom wall and the baffle plate may be designed with appropriate ridges, partitions, depressions, and the like such that the container is dedicated to accommodating a preselected type of medical apparatus, items, or other equipment. Larger and smaller containers may also be provided. A plurality of smaller containers might even be provided within the basin and have their contents sterilized concurrently. It is intended that the invention be construed as including all such alterations and modifications insofar as they come within the scope of the appended claims or the equivalents thereof.