Technical field

The present invention relates to a ventilation system for an operating room.

Background

At a hospital, operations are carried out in an operating room, where surgical operations are carried out in a sterile environment. An operating room (also known as an operating theater, or operating suite) may be a rectangular or square room, which can be divided into four areas:

Area 1, Surgical Area: In this area surgery is carried out and many people per square meter are present. The staff is in sterile clothing and there are sterile instruments.

Area 2, Instrument Area: In this area, sterile instruments are present on designated tables and staff is coming and going.

Area 3, Anesthetic Area: In this area, many people per square meter from the anesthetic staff are present. This area has lower hygiene requirements compared to Areas 1 and 2.

Area 4, Other Area : In this area, staff is coming and going. This may be an area for passage between the operating room and the corridor and a working space for staff in non-sterile clothing.

The four areas are illustrated in figure 1.

It has long been known that one of the key factors to prevent surgical site infections is use of air having a low concentration of viable bacteria. With the increasing occurrence of antibiotic- resistant bacteria that cause surgical site infections, reliance on antibiotic prophylaxis cannot continue. Thus, ventilation of the operating room must be as efficient as possible. Today, the risk for infection after a surgery is partly related to the concentration of Colony Forming Unit (CFU) in the air around the surgical Area 1 and the instrument Area 2. CFU/m ³ is a measure for the number of bacteria and other infectants (microbes, viruses, etc.) present in the air.

CFU are introduced to the air partly from staff in the operating room and from air flowing into the operating room, e.g. when doors are opened to adjoining areas. Such adjoining areas are for example corridors or other rooms with lower requirement for air quality in terms of CFU/m ³ . CFU/m ³ in an operating room depends, among others, on the number of people in the operating room, what clothes they wear, the ventilation system used and quality of air coming in through door openings.

A ventilation system supplies clean air to the operating room. For example, the ventilation system supplies clean air to the operating room from the ceiling of the operating room. The ventilation system also exhausts air from the operating room. The manner in which this is done affects the efficiency of the ventilation and thus the concentration of viable infectants in the operating room.

The requirement of clean air is highest around the operative Area 1, where surgery is performed and around the instrumental Area 2, where the sterile surgical equipment is present. Personnel in the operating room work primarily in two areas: the surgical Area 1 and the anesthetic Area 3. Air in the room flows between the four Areas. Air may flow between the Areas non-directionally or unidirectionally. The direction of the flow depends among others on the device used for input of air and the device(s) used for exhausting air. In other words, the type of ventilation system used in an operating room highly influences the flow of air between the different Areas.

Air supply can be designed to be an air-mixing system or an air-displacement system. An aim of a mixing ventilation system is to dilute contaminated air by reducing the CFU/m ³ .

An aim of a displacement ventilation system is to displace contaminated air by pushing clean air into the area. In an operation room, high air flows displacement systems are used to create piston ventilation, such as Laminar Air Flow ceilings (LAF-ceilings). In LAF-ceiling, air is distributed as a unidirectional flow with micro-turbulence. The systems are also known as Unidirectional Flow systems.

LAF-ceiling area is commonly used in operation rooms. In LAF-ceiling, air is supplied from the ceiling over the operating table and exhausted at a high and low location in all four corners of the operating room. Exhausting units are configured to exhaust equal amount of air per time unit in each corner, i.e. 25% of the total amount of exhausted air is exhausted in each corner. This is called symmetric exhaust according to DIN-standard. Usually, 1/4 of the exhausting units are positioned in the proximity of the ceiling of the operating room and 3/4 of the exhausting units are positioned in the proximity of the floor of the operating room. The lower positioned exhaust units exhaust about 75% of the air and the higher positioned exhaust units exhaust about 25% of the air. The system provides for a very low CFU presence in the surgical Area (< 3 CFU/m ³ ) and around the instrumental Area 2. However, the known systems are not able to achieve equal CFU/m ³ level throughout the room. The concentration of CFU is always higher in the proximity of staff and/or an open door compared to other Areas in the room. Besides, the flow of air from the LAF-ceiling prevents an accumulation of CFU in the surgical Area. But, this air flow can be disrupted by movement of the staff present in the room, which in turn reduces the protective effect of the air supply on the surgical Area.

A mixing ventilation system will not be able to achieve equal CFU levels in the whole room. The concentration of CFU will be higher in proximity of staff or an open door.

There is a need to increase the cleanliness of operating rooms, to reduce CFU/m ³ , minimize the spread of CFU and to reduce the risk of infections for the patients, such as surgical site infections.

It is an aim of the present invention to at least partly overcome the above-mentioned problem, and to provide an improved ventilation system for an operating room.

An aim of the invention is to increase the efficiency of the ventilation and reduce the concentration of viable bacteria in the operating room. This aim is achieved by the system as defined in claim 1.

The system comprises a ventilation system for an operating room. The operating room comprising a surgical Area where the patient and surgical personnel are positioned during surgery, an anesthetics Area where the anesthetics personnel are positioned during surgery, and a door to an outside of the operating room. The ventilation system comprises a plurality of first exhausting units positioned in the proximity of at least two corners of the operating room, and a second exhausting unit positioned with its center point at least 2 meters above floor level and within 3 meters from a center point of an upper frame of the door. The second exhausting unit is configured to exhaust more air per time unit than any one of the first exhausting units individually.

An asymmetric air outlet construction is provided to reduce the risk of spreading air with low quality (i.e. > 3 CFU/m ³ ) to the surgical Area and instrument Area, e.g. from the anesthesia Area or when a door is opened. An air outlet, i.e. the second exhausting unit, with a dominating part of the total air exhaust is positioned in closeness of the door. With dominating part is meant that the second exhausting unit exhaust more air per time unit than each of the other exhausting units, i.e. the first exhausting units, individually.

For a mixing ventilation system with a high airflow, an air outlet construction with a high degree of asymmetry will create a mass effect that will affect directions of air movements in the whole room. This will reduce CFU/m ³ in Area 1.

The system provides a high ventilation efficiency by positioning a domination part of the air exhaust in an area with a higher concentration of CFU in the air (e.g. 5 or more CFU/m ³ ).

According to some aspects, the second exhausting unit is configured to exhaust more or equal to 25% of the total room air exhaust per time unit. The amount of exhaust of air from the second exhausting unit depends on the number of first exhausting units and also on the number of times the door opens to the outside of the operating room and the number of people in the room. According to some aspects, the opening of the door automatically increases the exhaust rate of the second exhausting unit. According to some aspects, the second exhausting unit is configured to exhaust more or equal to 33% of the total room air exhaust per time unit.

According to some aspects, the second exhausting unit is positioned in or on the ceiling of the operating room. The location of the second exhausting unit will depend on the set up of the operating room and the space available for positioning a second exhausting unit. Preferably, the second exhausting unit is positioned in or on the ceiling. It may be that the layout of the operating room is such that there is no room for the second exhausting unit in or on the ceiling, in which case the second unit can be positioned in or on a wall.

According to some aspects, the second exhausting unit comprises more than one exhausting unit. It may be more efficient, and/or more cost effective to arrange more than one second exhausting units next to each other. According to some aspects, the second exhausting unit is positioned with its center point within 2 meters from a center point of an upper frame of the door. Depending on the size and layout of the room, the distance between the center point of the second exhausting unit and the center point of the upper frame of the door can be adapted. In a small operating room, the distance may for example be one meter or even shorter than one meter.

According to some aspects, the air supply unit comprises a LAF-ceiling arranged to create a unidirectional air flow for supplying air from the ceiling over the operating table.

According to some aspects, the LAF-ceiling comprises nozzles arranged to exhaust air in a direction different than the unidirectional flow for creating turbulence in the air flow.

Brief description of the drawings

The invention will now be explained more closely by the description of different embodiments of the invention and with reference to the appended figures.

Fig. 1 shows a top view of an example set up of an operating room with the four Areas.

Fig. 2 shows a side view of an example set up of an operating room.

Fig. 3 shows a diagram indicating the air quality requirements versus CFU load in the different Areas of the operating room.

Fig. 4 shows an top view of an operating room with the exhausting units and indicating a maximum distance between the centre of the door and the centre point of the second exhaust unit. The bottom part shows a side view of a cut out at line X of the middle part of the room.

Fig. 5a, 5b, 5c shows a top view of the same room as figure 1 indicating the air quality requirements versus CFU load in the different Areas of the operating room. The bottom parts show a side view of the same rooms.

Fig. 6 shows the airflow from a LAF ceiling over an operating table with a lamp over the table. Fig. 7a shows a simplified view of nozzles in the LAF ceiling for creating a turbulent air flow. Fig. 7b shows an example of a nozzle.

Fig. 8 shows the airflow from a LAF ceiling with nozzles over an operating table with a lamp over the table.

Fig. 9 shows the airflow in an operating room installed with a LAF ceiling with nozzles over an operating table.

Fig. lOa-e shows different examples of how nozzles may be designed.

Detailed description

Aspects of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings. The system disclosed herein can, however, be realized in many different forms and should not be construed as being limited to the aspects set forth herein. Like numbers in the drawings refer to like elements throughout.

The terminology used herein is for the purpose of describing particular aspects of the disclosure only and is not intended to limit the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

Figures 1 and 2 shows an operating room. The room may be square or rectangular with at least one door positioned in at least one wall, The room can be divided into four Areas:

Area 1, Surgical Area: In this area surgery is performed and many people per square meter are present. The staff SI is in sterile clothing and there are sterile instruments.

Area 2, Instrument Area: In this area there are sterile instruments 10 on designated tables, separate to the surgical area.

Area 3, Anesthetic Area: Anesthesia staff S3 working area. Also, in this area, there are many people per square meter. This area has lower hygiene requirements compared to Area 1 and 2 because it is not so closely associated with the surgical site of the patient.

Area 4, Other Area: In this are there is staff S4 coming and going and no instruments are present. This is an area for passage between the operating room and the corridor. This is also a working space for staff in non-sterile clothing.

Figure 3 shows a diagram indicating the air quality requirements versus CFU load in the different Areas of the operating room. In Area 4, the Other Area, there are few people and the air quality requirements are low since the patient 5 is not near this area. In Area 3, the Anaesthesia Area 3, there are more people per m ² than in Area 4 but the air quality requirements are about the same. In Area 2, the Instrument Area, the air quality requirements are high but the CFU load is normally low enough not to cause a problem for the required air quality. The low CFU load is mainly due to a reduced number of people per m ² in the Area. In Area 1, the Surgical Area, the air quality requirements are high while the CFU load is increased compared to Area 4. One reason is the presence of many people per m ² in this Area 1. This Area puts high demand on the ventilation system in the room.

The ventilation system comprises a plurality of first exhausting units 6 positioned in the proximity of at least two corners of the operating room and a second exhausting unit 7. The second unit has a center point 7c and is positioned at least 2 meters above floor level. The second exhausting unit is positioned within 3 meters from a center point 8c of an upper frame of the door 8. The second exhausting unit 7 is configured to exhaust more air per time unit than any one of the first exhausting units 6 individually. Thus, the second exhausting unit 7 may be an air outlet with the dominating air exhaust, positioned in or on the ceiling or in or on a wall, > 2 meter from the floor and with its center point < 3 m from the center of the upper frame of the door. Depending on the size and layout of the room, the distance between the center point 7c of the second exhausting unit 7 and the center point 8c of the upper frame of the door 8 can be adapted. In a small operating room, the distance may be for example 1.5 meters, 1 meter or even less than 1 meter.

The second exhausting unit is, for example, positioned in or on the ceiling of the operating room. The location of the second exhausting unit 7 will depend on the set up of the operating room and the place available for positioning the second exhausting unit. Preferably, the second exhausting unit is positioned in or on the ceiling, but it may be that the layout of the operating room is such that there is no room for the second exhausting unit in or on the ceiling and it is then positioned in or on a wall. The limitations of it being positioned with its center point at least 2 meters above floor level and within 3 meters from a center point of an upper frame of the door also applies when the second exhausting unit is positioned in or on the ceiling.

To improve efficiency, and/or cost effectiveness, more than one second exhausting units may be used. These second units may be positioned in proximity or next to or attached to each other. According to some aspects, the second exhausting unit comprises more than one exhausting unit.

Figure 4 illustrates an operating room from above. The bottom part of the figure illustrates a cut through at line X of the top part so that the same room can be seen from a side view. In the bottom part is illustrated that the clean air is added to the room by the ventilation system. This clean air can be added from the ceiling above the operating table 12 in Surgical Area 1. In other words, the operating room has at least one air supply unit 9, which supplies clean air to the operating room. According to some aspects, the at least one air supply unit 9 is positioned in or on the ceiling of the operating room in Area 1. In another aspect, the at least one air supply unit is positioned in or on the ceiling of the operating room directly above the operation table 12.

In figure 1, 2 and 4 is shown that first exhausting units 6 of the ventilation system are arranged/ disposed, located, placed/positioned in the proximity of the four corners. In the bottom part of figure 4, the first exhausting units are present in the proximity of the ceiling and in the proximity of the floor. A second exhausting unit is positioned in the proximity of the door 8, which closes an opening between the operating room and the outside of the operating room, for example a corridor. The second exhausting unit 7 is configured to exhaust more amount of air per time unit than the first exhausting units individually. Preferably, the second exhausting unit 7 is positioned in the proximity of, or in, or on, the ceiling of the operating room, preferably in the ceiling.

An asymmetric air outlet construction 7 is used to reduce the risk of spreading air with low quality (> 4 CFU/m ³ ) to the Surgical Area 1 and Instrument Area 2. An air outlet, i.e., the second exhausting unit 7, with a dominating part of the total air exhaust, is positioned in closeness of the door 8. The second exhausting unit is preferably positioned in association with Anesthesia Area 3, such that air from this Area 3 does not flow to Area 1 or 2. If the door is located as shown in figure 1 and 4, i.e. in the same side of the operating room as the Anesthesia Area 3, the second exhausting unit can be positioned with its center point 7c between the door 8 and the Anesthesia Area 3. The second exhausting unit is for example positioned in the ceiling or in a wall near the ceiling, with its center point positioned between the Anesthesia Area 3 and the door 8. With dominating part is meant that the second exhausting unit 7 exhausts more air per time unit than each of the first exhausting units 6, individually.

If a second exhaust system is used in combination with mixing ventilation will affect the air movements in the whole room and thus improve air quality in the surgical area (Area 1.)

The system provides a high ventilation efficiency by positioning a dominating part of the air exhaust in an area with a high concentration of CFU (>3.5/m ³ ) in the air.

As previously mentioned and according to some aspects, the second exhausting unit is configured to exhaust more or equal to 25%, or between 24 and 50%, of the total room air exhaust per time unit. The amount of exhaust of air per time unit from the second exhausting unit relative to the total amount of exhaust from the first and second units together, depends, for example, on the number of first exhausting units, on the number of times that the door opens, the number of staff S in the room and the like. According to some aspects, the opening of the door automatically increases the exhaust rate of the second exhausting unit. According to other aspects, the exhaust of the first and/or second exhausting units is increased, when the CFU level raises above a predetermined value. In other words, opening of the door may automatically trigger the exhaust rate of the first and/or second exhaust unit to increase for a predetermined amount of time. For example, the exhaust rate of the second exhausting unit is 25% of the total air exhaust from the room per time unit and when the door in opened, the exhaust rate is increased to 33% for a specified amount of time. The specified predetermined amount of time is for example any time between 15 seconds to 3 minutes. For example, 1 minute or 2 minutes. According to some aspects, the second exhausting unit is configured to exhaust more or equal to 33%, or between 25 and 40%, of the total room air exhaust per time unit.

For example, the second exhausting unit may be arranged to exhaust about 32% of the total amount of exhausted air, and the first exhausting units may be arranged to exhaust about 17% of the total amount of exhausted air in each of the four corners. This is a so-called asymmetric exhaust air. Asymmetric air flow improves air flow in the room, especially the flow of air around objects and persons in the room, thereby reducing the risk for accumulation of bacteria and the like around such objects.

An example ventilation system will now be described with an example. An operating room set up approximately according to figure 1 has 8 first exhausting units 6; two in each corner. One top first exhausting unit is positioned high in the wall, in the proximity of the ceiling, and one bottom first exhausting unit is positioned low in the wall, in the proximity of the floor. In each corner, the first exhausting units evacuate about 17% of the total amount of air evacuated from the room per time unit so that the total amount of air evacuated per time unit by all of the first exhausting units is about 68%. In each corner, the top first exhausting unit exhausts about 33% of the 17% and the bottom first exhausting unit exhausts about 67% of the 17%. The second exhausting unit 7 is positioned in the ceiling with its center point 7c within 3 meters from a center point 8c of an upper frame of the door 8. In this example, it is positioned with its center point 2 meters from the center point of the upper frame of the door. The ceiling of the example operating room is 2.7 meters high, therefore, the second exhausting unit is positioned 2.7 meters above the floor.

Figure 5 illustrates the effect of the ventilation system of the invention. The upper part of the figure illustrates an operating room from above. The bottom part of the figure illustrates a side view of the same room. On the left, figures 5a illustrates the effect obtained with a DIN- standard ventilation system as used today. It is obvious from figure 5a that the amount of CFU/m ³ is highest in Areas 1 and 3 and less in Areas 2 and 4. Figure 5b illustrates that the CFU/m ³ is reduced in all Areas 1 to 4 using the ventilation system of the invention. Figure 5c illustrates the effect of a system, wherein the second exhausting unit 7 is positioned low behind Area 3. It is obvious from figure 5c that the CFU/m ³ is higher compared to figure 5b, where the second exhausting unit 7 is position high up in the ceiling.

Figure 6 shows the airflow from a LAF ceiling 11 over an operating table 12 with a lamp 14 over the table 12. As can be seen in the figure, the air under the lamp 14 can become stagnant or just circulate under the lamp 14. CFU/m ³ may increase in the area under the lamp 14 since the air may not be continuously changed. This effect will differ greatly between operating rooms with different lamps 14 over the operating table 12.

Figure 7a shows a simplified view of a solution to the problem of stagnant air under an operating lamp 14 with nozzles 13 in the LAF ceiling 11 for creating a turbulent air flow. In other words, in the illustrated example of figure 7a, the air supply unit comprises a LAF-ceiling arranged to create a unidirectional air flow for supplying air from the ceiling over the operating table 12 and the LAF ceiling comprises nozzles 13 arranged to exhaust air in a direction different than the unidirectional flow for creating turbulence in the air flow.

LAF ceilings are well known in the art. LAF ceilings in general comprises some kind of airflow producing unit, filters for filtrating the air and an exhaust surface with holes or mesh or the like for allowing the air to flow downwards in a unidirectional flow.

The nozzles are, according to some aspects, protrusions in the exhaust surface that concentrates and directs the air flow of the LAF ceiling. The nozzles may thus be protrusions in the exhaust surface which has a tapering profile in the direction of the desired air flow to concentrate the flowing air. The tapering profile of the nozzles is for example that the nozzles have a cut off cone shape or have a step wise cone shape with a cut off end. Thus, the nozzles 13 comprises for example funnel shaped pipes in which the air enters the funnel at the wider side and leaves the funnel in the narrower side so that the air pressure increases in the funnel. Figure 7b shows an example of a nozzle from above to the left and from the side to the right. The protrusions are angled such that the air flowing out of them is different from the angle of the unidirectional air flow of the rest of the LAF ceiling. According to some aspects, the nozzles are angled between 20° and 70° as compared to a plane defined by the exhaust surface of the LAF ceiling. Preferably, the angle is between 25° and 50° and even more preferably between 30° and 45°.

The nozzles are, according to some aspects, inclined to be directed towards a center of the LAF ceiling. Thus, the air flow from the nozzles is directed to coincide under the LAF ceiling at a central part. That the air flow is directed towards a central part means that the air flow is directed towards a line that is extending vertically down from the middle of the LAF ceiling.

Figure 8 shows the airflow from a LAF ceiling 11 with nozzles 13 over an operating table 12 with a lamp 14 over the table 12. As can be seen in the figure, the nozzles direct the air flow such that it interrupts the stagnant air that can form under the lamp 14. In this example, the nozzles are arranged in a cross shape, with four nozzles on each leg of the cross. Depending on the size of the LAF ceiling, more or less nozzles may be required. It may also be that the nozzles are arranged on more than four legs of a cross or that there are different number of nozzles on different legs.

According to some aspects, the nozzles may be angled at different angles. For example, the nozzles closest to the central part may be angled 70° as compared to a plane defined by the exhaust surface of the LAF ceiling and then the angle may gradually decrease for nozzles further and further away from the central part. The nozzles furthest from the central part are, for example, angled 20°. The angles may of course differ between different sizes of LAG ceilings. The angles of the nozzles may also be chosen depending on the height of the ceiling in the operating room it is used in.

Figure 9 shows the airflow in an operating room installed with a LAF ceiling 11 with nozzles 13 over an operating table 12.

According to some aspects, it may be that the nozzles are not connected to the same air flow as the rest of the LAF ceiling; the nozzles may have a separate air flow and thus a separate unit for creating the air flow.

Figure lOa-e shows different examples of how nozzles may be designed. Figure 10a shows a cut off cone shape where the air flow enters in the bottom part and exhaust in the narrower top part. In figure 10b there is illustrated a nozzle that is inclined in its form. Figure 10c shows an example of a nozzle which tapers irregularly. Figures lOd and lOe shows example nozzles where the exhaust opening is not in the same plane as the exhaust surface but inclined. The nozzle may thus not be attached to the exhaust surface at an inclination; the shape of the nozzle provides the angled air flow.

The size of the nozzle may vary depending on the size of the LAF ceiling or the air flow required in a specific set up of a LAF ceiling. The nozzles may for example be between 50 and 70 mm high and between 20 and 40 mm wide. Please note that the nozzles may be arranged behind the exhaust surface. In other words, the nozzles may be arranged on the inside of the LAF ceiling, on the inner side of the exhaust surface.

It should be noted that the solution with the nozzles in the LAF ceiling ca n be operating separately of the rest of the invention. In other words, the nozzles in the LAF ceiling are not dependent on the ventilation system to function.

Reference list:

1. Area 1

2. Area 2

3. Area 3

4. Area 4

5. Patient

6. First exhaust unit

7. Second exhausting unit

c. Center point of second exhaust unit

8. Door

c. Center point of door

9. Air supply unit

10. Instruments

11. LAF ceiling

12. Operating table

13. Nozzle

14. Lamp

S. Staff/personnel/people

SI surgical staff

53 anesthetic staff

54 other staff