Patent Application
20100234794
The present invention generally relates to a system and method for reducing the incidence of surgical site infection, and more specifically to apparatuses and methods for using and directing gases useful in reducing the incidence of surgical site infection.
Infections contracted in hospitals and other health care facilities are the fourth largest killer in America. Every year in this country, almost two million patients contract infections in hospitals, and an estimated 103,000 die as a result, as many deaths as from AIDS, breast cancer, and auto accidents combined. These deaths are largely due to respiratory system infections, urinary tract infections, catheter related infections, and surgical site infections resulting from accidental exposure to pathogens. The risk of surgical site infection is present in all surgical procedures, but can be particularly serious in certain operations, such as cardiovascular surgery and joint replacement.
Rigorous adherence to the principles of asepsis is the foundation of surgical site infection prevention. It is critical to minimize a patient's exposure to bacterial contamination (as well as other pathogens) from members of the surgical team and from non-sterile equipment or surfaces in the operating room through the use of gloves, gowns, masks, and drapes. Draping of the surgical site provides a sterile work surface and helps minimize the transfer of microorganisms between non-sterile areas and the surgical wound. These measures also help protect health care professionals from exposure to pathogens in the patient's blood and other body fluids.
It has been long recognized that hand hygiene is also a very important exercise to reduce infection in the operating room and in other patient locations within a health care facility. Surgeons and staff are trained to wash their hands extensively prior to putting on sterile gloves. In addition, solutions with anti-microbial activity are frequently used to scrub the patient and prospective surgical site prior to surgery. Surgeons and all personnel within the sterile field wear sterile gowns, gloves, and masks. Their hair is typically covered with a hair net or hat. Prophylactic antibiotics may also be given to the patient as part of the surgical preparation. In addition, all instruments and medical devices are sterilized prior to the procedure.
Despite compliance of the surgeon and surgical staff with rigorous hygiene principals and infection control protocols, airflow in the operating room can affect infection rates by allowing certain bacteria to get to a wound or other access site in a patient. The bacteria can be blown into the wound from health care providers' (surgeon, nurses, anesthesiologist, technicians, etc.) skin, hair, clothing, or hands. In addition, bacteria or other pathogens can contaminate an open wound, for example, when entrained in air entering the operating room while a door to the operating room is open. Bacteria or other pathogens from a prior surgical procedure or cleaning exercise by cleaning staff may become airborne. As a result, and in an attempt to mitigate and/or prevent such contamination, laminar flow of HEPA-filtered air has also been employed in the operating room to reduce scatter of bacteria into a surgical wound. Conventional laminar flow systems operate by drawing ambient air, under negative pressure, into a laminar flow unit. This air first passes through a pre-filter which traps the larger size dust and dirt particles. A blower in the unit then directs this pre-filtered air, now under positive pressure, through a conventionally-known 99.97% efficient HEPA filter to generate sterile, unidirectional ultra-clean air. The HEPA filter can remove particles down to a size of 0.30 microns. Viruses range in size from 0.01 microns to 0.03 microns.
Bacteria range in size from 0.1-15 microns. Other pathogens such as protozoa can be even larger. It is also recognized that many pathogens are typically attached to dust particles, or contained in droplets, although they may be also individually entrained in an air stream or draft. When the laminar air moves in one direction at a uniform speed of between 70-120 FPM, its individual molecules assume parallel paths, or streamlines. The physics of this phenomenon allow for these streamlines of air to bend around objects and obstacles without losing laminarity or losing the particles that they carry. Currently, the use of laminar flow air involves directing HEPA filtered air from wall or ceiling vents to floor vents. Because of the parallel stream lines, entrained particles will remain entrained in the airstream until a turbulent condition is encountered.
Such conventional ventilation systems are widely used in operating rooms in many countries around the world. These systems entail high investment costs and operating expenses, and must be properly and constantly maintained to be effective. A recent study by Brandt, et al. (Operating Room Ventilation with Laminar Air Flow Shows No Protective Effect on the Surgical Site Infection Rate in Orthopedic and Abdominal Surgery; Annals of Surgery, Volume 28, Number 5, Pages 695-700, November, 2008) evaluated whether operating room ventilation with vertical laminar airflow impacts surgical site infection rates. Surprisingly, they found that operating room ventilation with laminar airflow showed no benefit and was, surprisingly, even associated with a significantly higher risk for severe infections. The authors hypothesized that the reason for this surprising finding is that the heads of the surgical team members may be positioned above the surgical site, i.e., directly in the laminar airstream from the ceiling down to the wound. This may facilitate pathogen containing particles such as droplets and skin particles, falling directly into the wound with the downstream airflow. Another hypothesis proposed by the authors was that the ventilation may allow cooler air to fall into the wound, lowering intra-operative tissue temperatures. Lowering of body temperature is known to increase the chance of surgical site infection, and a local decrease in temperature could theoretically increase the chances of surgical site infection as well.
Unfortunately, current ventilation systems designed to reduce surgical site infections are expensive to install and maintain and may still allow bacteria to enter the surgical wound from any non-sterile, shedding surfaces that are very close to the surgical wound. This is evident since surgical site infection remains a source of illness and possible cause of death in the surgical patient. In addition, infections acquired during surgery invariably result in longer hospitalization and higher costs. Hospitals may soon be denied reimbursement costs for those cases where an infection was deemed to be acquired in the hospital, i.e., a so called “never event”. Accordingly, there is a need in this art for novel apparatuses and methods for delivering gases directly over or in close proximity to a wound or surgical site in order to reduce or prevent pathogens from contacting or entering the wound, and thereby reduce the incidence of infections.
It is an object of the present invention to provide a system for preventing or reducing the incidence of infection during a surgical procedure or during treatment in a healthcare facility. Therefore, a system is disclosed for preventing infection of a surgical site, wherein the surgical site is a wound or instrument. The system is comprised of a source of air that is coupled to a manifold having a wall, a proximal end, distal end, and a lumen therein. The air enters the lumen of the manifold and then exits at least one opening in the wall of the manifold. The manifold is attached to a substrate proximate a surgical site by an attachment means or attachment member such as clamp, a shaft, bracket, screw, adhesive, cable, chain, wire, staple, or velcro. The substrate is typically a surgical retractor, bed, bedrail, or instrument stand. Preferably, the attachment means or attachment member is a shaft having a proximal end and a distal end, the proximal end adapted to be secured to the substrate, and the distal end of the shaft attached to the manifold. Air exiting the manifold passes directly over the surgical site so as to prevent airborne pathogens such as bacteria and pathogen- laden particles from entering or contaminating the surgical site.
In one embodiment, the source of air is comprised of a power supply, a a fan or blower, a filter, and coupling means for delivering the air to the manifold. In another embodiment, the source of air can be a compressed air source, e.g., in a tank under pressure. The air may contain carbon dioxide or a dilute solution of anti-microbial agent or antibiotics. In another embodiment, the shaft is flexible or articulated and is pivotably coupled to the manifold. In yet another embodiment, the system further comprises an ultraviolet or blue light source producing a wavelength within the range of 200-400 nm or 440-490 nm, respectively. Antibiotic-resistant bacterial infections represent an important and increasing public health threat. At present, fewer than 5% of staphylococcal strains are susceptible to penicillin, while approximately 40%-50% of Staphylococcus aureus isolated have developed resistance to newer semisynthetic antibiotics such as methicillin. In still yet another embodiment, the light emits blue light with a wavelength of 440-490 nm, preferably at 470 nm. This light has been demonstrated to be effective in killing methicillin resistant Staphyloccoccus aureus (MRSA).
Another aspect of the present invention is a method for performing a surgical procedure, the method includes providing a source of air that is coupled to a manifold having a wall, a proximal end, distal end, and a lumen therein. The air enters the lumen of the manifold and then exits at least one opening in the wall of the manifold. The manifold is attached proximate a surgical site by attachment means including a clamp, a shaft, bracket, screw, adhesive, cable, chain, wire, staple, or velcro. The substrate is typically a surgical retractor, bed, bedrail, or instrument stand. The substrate as contemplated by the present invention can also be a surface of the patient's body. Preferably, the attachment means useful in the method of the present invention is a shaft having a proximal end and a distal end, the proximal end adapted to be secured to the substrate, and the distal end of the shaft attached to the manifold. Air exiting the manifold passes directly over the surgical site so as to prevent airborne bacteria and bacteria laden particles from entering the surgical site.
In one embodiment, the source of air is comprised of a power supply, a fan, a filter, and coupling means for delivering the air to the manifold. In another embodiment, the method mixes the source of air with carbon dioxide, an anti-microbial agent, or an antibiotic to further aid in preventing contamination of the surgical site.
In yet another embodiment, the method includes adding an ultraviolet light (200-400 nm) or blue light (440-490 nm) source to the system.
In still yet another embodiment, the method includes providing a plurality of these devices, with at least one device coupled to a negative source of air and at least one device coupled to a positive source of air.
These and other aspects and advantages of the present invention will become more apparent from the following description and examples, and accompanying drawings.
Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention that may be embodied in other specific structure and are not limited thereto. While the preferred embodiments have been described, the details may be changed without departing from the spirit and scope of the invention, which is defined by the claims.
As used herein the term “laminar flow” is defined to mean a flow of air moving with uniform velocity and direction with a minimum amount of turbulence. The term “turbulent flow” is defined to mean a flow of air having a non-uniform or random direction with varying velocity. The term “air stream” is defined to mean air exiting a manifold and having a general direction with varying degrees of laminar and turbulent properties. The term “surgical site” is defined to mean a surgical wound, a traumatic wound, or a table or instrument required for surgery
The manifold 12 illustrated in
Various shapes for the air holes 214 can be formed so as to control the direction, velocity, and turbulence within the air flow. For example, the air holes can be rectangular, triangular, circular, or elliptically shaped. The air holes 214 extend through side wall 215 and are in communication with lumen 223. If desired, two manifolds of the present invention can be placed adjacent to one another, with one manifold delivering air at a first velocity and another manifold delivering air at a second velocity. Air exiting holes 214 in the manifold 21 is directed immediately over a surgical site, thereby reducing the likelihood of foreign material such as airborne bacteria, epithelial cells, dust, or bacteria laden microparticles from entering the site. The air delivered can be in a laminar form or non-laminar (turbulent) curtain of air. The air curtain can be delivered parallel to the surgical site and the height of the air curtain relative to the surgical site is easily adjusted by adjusting the shaft 22 or the coupling point 221 between the shaft 22 and the manifold 21. For a shaft having articulating members 222 disposed over a cable 223, the height of the manifold relative to the surgical site can be adjusted by loosening the cable 223 within the shaft 22, adjusting the height, and then applying tension to the cable 223 by using a tensioning arm 224 or equivalent. Other means for adjusting the height can be to use magnetorheological or electrorheological fluids within the shaft 22. In the embodiment that uses magnetorheological or electrorheological media in the shaft, a magnetic or electric field would also need to be supplied to the shaft 22, respectively. Higher heights of the air stream relative to the surgical site allow for the surgeon's hands and tools to operate below the airflow stream. Lower heights reduce the chance bacteria can enter the site, but are somewhat compromised by turbulence created by the surgeons hands and instruments. Nonetheless, the air stream can reduce airborne bacteria and particulates such as skin cells, hair, dust, etc. from entering the surgical site. In the preferred embodiments of the system and method, the air is delivered proximate a surgical site, preferably within about 2-36 inches above the sitedepending upon the operating room environment, the surgical procedure being performed, and other circumstances. Delivering the air proximate a surgical site, with no potential sources of contamination such as people or non-airborne bacteria between the surgical site and the air leaving the manifold, therefore reduces or eliminates the likelihood of contamination of the surgical site. The direction of airflow can be adjusted by tilting the manifold in one or more directions. Thus, airflow can move in a vertical direction if an air wall is needed or desired. Alternatively, the manifold 21 delivers air in a direction perpendicular to the surgical site 23. The air stream can be adjusted to be laminar, laminar-like or turbulent when using the systems of the present invention. For a more laminar air flow, a straight manifold having a fixed lumenal diameter of about 1-5 mm can be used. For a more turbulent air flow, larger lumens with varying diameters of about 6-10 mm can be employed. The lumenal surface of the manifold can also be roughened to enhance turbulence. The manifold can also be curved to increase turbulence
Referring now to
Another embodiment of the present invention is illustrated in
The present invention provides a great deal of freedom to the surgical staff with respect to exactly where and how each manifold delivers air. For example, air entering the manifold can optionally be pre-filtered with a HEPA filter, for example. In one embodiment, the air entering the manifold can be heated. Heating the air helps to avoid hypothermia, a condition known to increase the risk of surgical site infections. In another embodiment, the air is mixed with a dilute solution or mist of an antibiotic or anti-microbial agent. In another embodiment, the air is humidified with a sterile solution. The air may also be passed through a nebulizer just prior to entering the manifold. The HEPA filtered air can be directed in any number of directions and on multiple surgical sites, if these exist. In addition to adhesive as a way to attach the manifold to surfaces such as drapes, retractors, rails, clothing, etc., other conventional attachment devices or components such as velcro, pins, staples, tape, snaps, buttons, or sutures and the like can also be used.
Furthermore, the systems of the present invention can optionally be fitted with a source of UV (200-400 nm) or blue light (440-490 nm) to shine on the surgical site. The light can be placed on or attached to the manifold. The preferred wavelength of ultraviolet light is 254 nm. The preferred wavelength of blue light is 470 nm. Alternatively, the UV or blue light can be used separately, i.e., not attached to the manifold. Multiple manifolds can be used on one surgical site. At least one of these manifolds can be coupled to a negative pressure source coupled to a vacuum. The combination of a negative pressure source facing a positive air pressure may help to create a stronger and more aligned air flow to prevent intra-operative infection. For any of the embodiments illustrated herein, an “air curtain”, having a substantially non-laminar profile, can also be used. Although desired, laminar air flow per se is not a pre-requisite to the functioning of the device. In addition, while the drawings herein illustrate delivery heads with a plurality of holes, a single slit can also be used, the slit formed for at least a portion of the length of the air producing side of the manifold. The direction that the airflow is directed over the surgical site is easily adjusted by a surgeon or member of the surgeons staff by tilting or rotating any of the manifolds or shafts of the embodiments described herein. The preferred velocity of air flow for turbulent or laminar air flow profiles will be between about 25-300 feet per minute (FPM), and preferably within the range of about 70-120 FPM.
The following examples are illustrative of the principles and practice of the present invention, although not limited thereto.
The system illustrated in
A surgical procedure that would benefit from the present invention is a surgical repair of a ventral hernia. The surgical team prepares for the surgical procedure in the following manner. A patient is prepared for surgery in a conventional manner by use of proper anesthesia, and prophylactic antibiotics, if necessary. The skin near and around the surgical site is cleaned with an antimicrobial agent such as iodine or chlorhexidine gluconate. The surgical site is then draped so as to minimize both the surgical site area and exposure of the surgical site to sites that were not cleaned by the surgical team. The system for reducing surgical site infection is placed near the proposed site of surgery. The flexible manifold illustrated in
Although this invention has been shown and described with respect to detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and scope of the claimed invention.
