+86 18186671616
Jason@cleanroomequips.com
Negative pressure wards provide good conditions for isolating infectious sources and blocking airborne diseases, which can minimize the spread of infectious diseases, protect medical staff from infection, and effectively prevent cross-infection between patients.
(Figure 1: Negative pressure isolation ward)
What is a negative pressure isolation ward
It is used to isolate patients with infectious diseases or suspected patients that are transmitted through and may be transmitted through the air. Ventilation is used to make the air in the ward area flow from the clean area to the contaminated area in a directional manner and make the static air pressure in the ward lower than the static air pressure in the surrounding adjacent areas to prevent pathogenic microorganisms from spreading outward.
Scope of application: It is suitable for the isolation of patients with respiratory diseases, such as pneumonic plague, SARS, human influenza, tuberculosis, measles, etc. It can also be applied to emergency treatment of some special pathogens or critical illnesses with unknown causes.
Building layout requirements
The distance between the negative pressure isolation ward and the surrounding buildings, such as dormitories and public buildings, should be at least 20m. If it is less than 20m, a fence should be set up; in general hospitals, negative pressure isolation wards should be set up independently. If they cannot be set up independently, they should be set up at one end (side) of the building and form a separate area; if they are set up in high-rise buildings, they should be close to the top floor; the entrances and exits of the ward where the isolation ward is located should be set up independently, and the clean and contaminated passages should be separated, and the two should not intersect; the location of the negative pressure isolation ward in the hospital to which it belongs should be downwind of the most wind direction throughout the year.
The ward composed of multiple wards should be strictly divided into clean area, semi-contaminated area and contaminated area, and a buffer zone should be set between the three areas; it is best to set up double corridors in the ward, inner corridor and outer corridor, the inner corridor is the medical staff passage, and the outer corridor is the patient passage.
(Figure 2: Respiratory diseases)
The ward should be equipped with a medical call intercom system, communication system, cable TV system, logistics system, and a closed-circuit television teaching system and an access control system to prevent unauthorized personnel from entering and exiting at will.
There should be a hand-washing branch, a shower room, a toilet and a hand-over window with double sliding doors in the negative pressure isolation ward. There should be a buffer room and a non-touch faucet between the ward door and the inner corridor to facilitate the staff to wash their hands, change isolation clothes and gloves, etc., and also prevent indoor microorganisms from directly entering the inner corridor. The hand-over window set on the wall of the inner corridor between the ward and it is best to be a mutually interlocking device.
Air conditioning and Ventilation system requirements
The ventilation system should make each functional area independent (self-circulating system), that is, the clean area, potential contaminated area and contaminated area should be equipped with air conditioning systems separately. The air conditioning and ventilation system can adopt a fresh air mode, a fan coil plus fresh air mode and an indoor self-circulating Air conditioning system equipped with a disinfection device. Negative pressure isolation wards cannot share central air conditioning with other wards in the hospital.
The fresh air in the isolation ward must come from the outside. It is strictly forbidden to indirect fresh air from the machine room, ceiling or corridor. The fresh air outlet should be away from the exhaust outlet of the building, the open cooling tower, the chimney exhaust outlet and various pollution sources, and be upwind of them. The fresh air collection port should be more than 3m from the ground. When it is installed on the roof, it should be more than 1m from the roof. The air supply speed of the fresh air outlet should not exceed 3m/s to avoid inhaling debris.
(Figure 3: Ward air conditioning and ventilation system)
The air supply outlet of the isolation ward should use low-resistance high-efficiency or above filtration equipment. The air quality should reach a total bacterial count of ≤500cfu/m3, and beta-hemolytic streptococci and Staphylococcus aureus should not be detected. For the exhaust of the negative pressure isolation ward, a high-efficiency filter of not less than Class B (with a filtration efficiency of not less than 99.99%) should be installed at the indoor air outlet.
The Ventilation frequency of the negative pressure isolation ward is 8-12 times, and the per capita fresh Air volume should not be less than 40m3/h. Other auxiliary rooms take 6-10 times. The exhaust of the negative pressure isolation ward should use a leak-proof exhaust device that can be safely unloaded.
The exhaust duct outlet cannot be located in the technical mezzanine or equipment layer. It should be directly connected to the outdoors. It should have a check valve and rain protection measures. It should be more than 20m away from the air inlet and be downwind. The purification air conditioning system should adopt a constant air volume system and operate 24 hours a day. The air volume should be set at low speed at night.
air flow requirements
The air flow organization should meet the principle of directional flow so that the air in the ward (ward) flows reasonably from the clean area to the contaminated area. The air supply and return air adopts the air flow organization of upper delivery and lower side return.
The total direction of the air flow is consistent with the direction of particle deposition. The air flow organization of upper delivery and upper return (small circulation, easy to raise dust) cannot be adopted.
The air flow direction must meet the principle of protecting medical staff and the principle of protecting patients from cross-infection.
(Figure 4: Ventilation in ward)
Negative pressure isolation wards are equipped with main air supply outlets and secondary air supply outlets. The main air supply outlet is placed on the ceiling of the regular standing position of medical staff beside the bed, and the distance from the head of the bed should be no more than 0.5m, and the length should not be less than 0.9m; the secondary air supply outlet is set on the ceiling at the end of the bed, and the distance from the end of the bed should be no more than 0.3m, and the length should not be less than 0.9m. The exhaust of the ward should be set at the place closest to the bed, and the appropriate location is the lower side of the head of the bed. The upper edge of the air outlet inlet should not be higher than 0.6m above the ground, and the lower edge should be higher than 0.1m above the ground; the wind speed of the return (exhaust) air outlet should not be greater than 1.5m/. The return air outlet should not be set at the entrance of the ward to avoid medical staff facing polluted air when opening the door, which may cause the risk of inhalation infection, and at the same time prevent the polluted air from escaping when opening the door.
The air supply outlet should be set on the center line of the ward for multi-person wards, and the position of the return air outlet should ensure that each bed is not downwind of each other. An airflow check valve should be set on the exhaust duct between the main exhaust systems to prevent air cross-contamination between wards.
Pressure control requirements
Pressure control decreases from clean area-semi-contaminated area-contaminated area in sequence to ensure that the clean area is at positive pressure and the contaminated area is at negative pressure. The air supply volume in the clean area is greater than the exhaust volume, and the exhaust volume in the contaminated area is greater than the air supply volume, so that the pressure in the ward is lower than the outdoor pressure.
The negative pressure levels in the ward are from high to low: bathroom, negative pressure isolation ward, buffer center, and inner corridor. The negative pressure isolation ward should be outside the ward, and a pressure difference sensor should be set in the middle to detect the negative pressure value or to automatically adjust the supply and exhaust volume of the ventilation system without setting the air volume valve.
The pressure difference (negative pressure) between adjacent rooms with different pollution levels is not less than 5Pa. The air pressure in the clean area should be kept positive relative to the outdoor atmospheric pressure.
(Figure 5: Ward pressure control)
Usage and management requirements
The pressure difference between the contaminated area and the potential contaminated area, and between the potential contaminated area and the clean area in the negative pressure isolation ward should be automatically monitored on the air conditioning system. Every time the medical staff enters the air isolation ward, they must first check whether the negative pressure value on the pressure gauge meets the predetermined pressure difference value. Only when the specified requirements are met can they enter the isolation ward.
The doors and windows of the isolation ward should be kept closed at all times.
When entering the air isolation ward, medical staff should wear secondary protective clothing, that is, wear medical protective masks, work clothes, isolation clothes or protective clothing, shoe covers, gloves, work hats, goggles or protective masks. Medical staff who perform aerosol-inducing operations should use third-level protection, that is, in addition to secondary protection, they should wear masks or full-face respirators.
(Figure 6: Layout of the isolation ward)
Understand the location of the exhaust vent to prevent wrong standing.
The air inlet filter should be equipped with an alarm device to replace the filter regularly to ensure that the system operates within the designed air volume range.
Maintain a reasonable bed spacing, the minimum distance between the bed and any fixed obstacle should be no less than 0.9m; one negative pressure ward should be arranged with one patient, and patients with the same respiratory disease can be arranged if conditions are unavailable, and the bed spacing should be greater than 1.1m.
Patients in respiratory isolation wards are restricted from going outside the ward, and patients should wear surgical masks when leaving the ward.
Room purification and disinfection devices should not be installed in negative pressure isolation wards; cleaning utensils in negative pressure isolation wards are fixed and dedicated, and they need to be disinfected and dried after use, and medical waste must be strictly handled.
(Figure 7: Clean isolation ward)
Cleaning staff are relatively fixed, and they need to be trained in infection control before taking up their posts, and they must strictly protect themselves; for surface disinfection of objects in isolation wards, medium and high efficiency disinfectants approved by the health administration department should be used, with effective concentrations and action times.
Filter replacement cycle: Air handling units and fresh air units should be inspected regularly and kept clean. The coarse filter of the fresh air unit should be cleaned every 2 days; the coarse filter should be replaced every January to February; the medium filter should be checked weekly and replaced every 3 months; the sub-high efficiency filter should be replaced every year, and replaced in time if contamination and blockage are found. The end high efficiency filter should be checked once a year, and replaced when the resistance exceeds the initial design resistance of 160Pa or has been used for more than 3 years. The medium efficiency filter in the exhaust fan unit should be replaced every year, and replaced in time if contamination and blockage are found. Regularly check the return Air Filter, clean it once a week and replace it once a year. If there is special contamination, replace it in time, and wipe the inner surface of the return air outlet with disinfectant.
Related definitions
Clean area: an area in the ward where respiratory infectious diseases are diagnosed and treated that is not easily contaminated by substances such as patient blood, body fluids and pathogenic microorganisms, and that patients with infectious diseases should not enter. Including medical staff's duty room, toilet, men's and women's locker room, bathroom, storage room, food preparation room, etc.
(Figure 8: Clean area)
Semi-contaminated area (potentially contaminated area): an area between the clean area and the contaminated area in the ward for the diagnosis and treatment of respiratory infectious diseases, which may be contaminated by the patient's blood, body fluids, pathogenic microorganisms and other substances. Including medical staff's office, treatment room, nurse station, patient's post-use items, medical equipment, etc., processing room, inner room, etc.
Contaminated area: an area where infectious disease patients and suspected infectious disease patients receive treatment in the ward for the diagnosis and treatment of respiratory infectious diseases, including the temporary storage and treatment of items contaminated by their blood, body fluids, secretions, and excrement. Including wards, treatment rooms, waste rooms, and patient admission and discharge treatment rooms, etc.
(Figure 9: Hospital contaminated area)
Buffer room: a small room with doors on both sides set up between the clean area and the potential contaminated area, and between the potential contaminated area and the contaminated area in the ward for the diagnosis and treatment of respiratory infectious diseases, which is a preparation room for medical staff.
