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Clean operating room decontamination solutions Negative pressure operating room to prevent cross infection A negative pressure clean operating room usually includes a ventilation system to allow air to flow into the negative pressure operating room from the corridor or any adjacent area, while ensuring that contamination is Air cannot escape from negative pressure operating rooms and into other areas of hospitals and health facilities.

Under natural conditions, air flows from the high pressure zone to the low pressure zone. If the operating room is under negative pressure, outside air will continuously flow into the room from under the door, while preventing gaseous pollution particles that grow in the room from escaping and entering the outside corridor. As an example of a common negative pressure room, a bathroom with an exhaust fan is a negative pressure room. Once the negative pressure condition is established, close the bathroom door and the fan will stop unpleasant odors and moisture from escaping the bathroom.

To create a negative pressure state, it can be achieved by balancing the ventilation system of the room so that more air is automatically exhausted than automatically supplied. This creates an unbalanced ventilation, with the room ventilation system constantly drawing in supplementary air from outside the room. In a well-designed negative pressure chamber, air flows in entirely through a gap (usually about half an inch high) under the door. In addition to this gap, this negative pressure chamber should be as airtight as possible to prevent air from entering through various other cracks and gaps, such as various gaps around windows, wall lighting, and socket outlets. Even if the room has achieved a negative pressure condition, the air leakage in these places may still offset or eliminate the negative pressure state of the room.

The minimum pressure differential required to achieve and maintain negative room pressure so that air flows into the room is very small (0.001 inches of water level gauge). The actual negative pressure value achieved depends on the difference between the ventilation system air consumption and supply and the structure and size of the room, including air flow paths and flow openings. If the room is well sealed, negative pressure values ​​higher than 0.001 inch water gauge are easily achieved. But if the room is poorly sealed, as is the case in many health facilities (especially older ones), achieving larger negative pressure values ​​may require a discharge/supply differential greater than the ventilation system capacity.

To achieve a negative pressure environment under the normal operation of a clean operating room ventilation system, first adjust the air flow supply and discharge in the room to achieve a discharge that is 10% higher than the supply or 50 cubic feet per minute higher (depending on the higher value) will do. In most cases, this standard can achieve a negative pressure value of at least 0.001 inch water level gauge. If the negative pressure value of the 0.001-inch water level gauge cannot be achieved, nor can it be achieved by increasing the flow difference (within the allowable range of the ventilation system), the room should be carefully inspected for gaps (such as door cracks, window cracks, plumbing fixtures and various fixtures built into walls, etc.) and then take remedial action to seal those cracks.

The negative pressure in the room can be changed by changing the operation of the ventilation system or opening and closing the door, hallway door or window of the room. If an operational structure has been established, ensure that all doors and windows in negative pressure rooms and other areas (such as hallway doors that affect air pressure) are properly closed, unless people need to enter or leave the room or area

Smoke test

A smoke test is a simple procedure used to determine if a room is already under negative pressure. Place a flamethrower under the negative pressure chamber door, about 2 inches away from the door. Squeeze the bulb of the fire tube lightly to allow the fire tube to produce a small amount of smoke. Holding the fire pipe parallel to the door, the smoke is slowly discharged from the pipe, making sure that the smoke discharge speed is lower than the air speed. If the room is already under negative pressure conditions, smoke will flow into the room from under the door. If the room is in a non-negative pressure condition, the smoke will blow out the door or remain stationary. The test must be performed with the door closed, and all windows in the clean operating room room must be tightly closed. If the room's air purifier is already running (including a fume hood or biosafety cabinet), it must remain running. If the room has an anteroom, the pressure difference from the corridor to the anteroom and from the anteroom to the room should be tested.

Infection transfer

The most common means of transmission of viral bacteria is through the respiratory system. When an infected patient coughs or sneezes, pollution particles containing droplet nuclei are emitted into the air. These particles are about 1-5 microns in diameter. Droplet nuclei may remain in the air for several hours, depending on the environment. The most powerful droplet nuclei may be as large as 5 microns in diameter. Droplet nuclei can be produced when speaking, coughing and sneezing. Each cough may produce 3000 droplet nuclei. Speaking for 5 minutes may produce 3000 droplet nuclei, and singing may produce 3000 droplet nuclei per minute. Sneezing produces the most droplet nuclei (tens of thousands) and can spread to people 3 meters away.

Air filters commonly used in air conditioning systems in medical institutions can effectively eliminate airborne droplet nuclei. In areas where medical institutions care for infected patients, the minimum standard should use pre-filtration systems and final filtration systems (sub-high-efficiency filters). Some of these areas have additionally installed HEPA filters. For particles 1-5 microns in diameter, a MERV 14 filter has an initial filtration efficiency of 95%.

Commonly used purification equipment in clean operating rooms include: laminar flow ceiling, high efficiency filter, air filter, transfer window, etc.