As a special public space, hospitals have distinct standards for air cleanliness and microbial control in different areas due to varying medical treatment needs. Liquid tank air filters, with their zero-leakage sealing structure, ability to intercept particles ranging from 0.1 to 0.3μm, and wide environmental adaptability, have become the core components of air purification systems in high-cleanliness areas of hospitals. The following analyzes the application logic and practical value of key purification scenarios in hospitals.
I. Purification Area of the Operating Department: Building a Sterile “Air barrier” during the operation
The operating department is the top priority in hospital infection control, especially for clean operating rooms, which need to simultaneously meet the three major requirements of “particle control”, “microbial interception” and “airflow stability”. The application of liquid bath air filters directly affects the incidence of surgical site infection (SSI).
Class I-II clean operating rooms (Class 100 / Class 1,000) : The “sterile defense line” for core surgeries
Suitable scenarios: Cardiac surgery (cardiopulmonary bypass surgery), neurosurgery (intracranial tumor resection), organ transplantation (liver/kidney transplantation), orthopedics (joint replacement surgery), and other surgeries that require an extremely sterile environment. For this type of surgery, the concentration of 0.5μm particles in the surgical area should be controlled at ≤350 particles /m³, and the bacterial concentration in the air should be ≤1cfu/30min · φ90mm petri dish to prevent the particles from carrying pathogenic bacteria and causing serious complications such as implant infection and intracranial infection.
Application logic
The “liquid tank high-efficiency filter + top supply air laminar flow system” is adopted, with the filter directly installed at the high-efficiency supply air outlet directly above the operating table. Its silicone gel sealing structure can achieve a seamless fit between the frame and the frame, with a leakage rate of ≤0.001%, completely preventing unfiltered air from seeping in through the gaps. When combined with ultra-fine glass fiber filter materials (with a filtration efficiency of ≥99.999% for 0.3μm particles), it can effectively intercept microbial carriers such as bacterial spores (such as Bacillus subtilis) and fungal spores (such as Aspergillus) in the air.
Actual case: In the cardiac surgery room of a tertiary hospital, after installing the liquid bath filter, the bacterial concentration in the air of the surgical area was stabilized at 0.6cfu/30min · φ90mm plates. The postoperative SSI incidence rate dropped from 3.5% to 0.9%, reaching the world’s top clean surgical standards.
2. Class III-IV Clean operating rooms (Class 10,000 / Class 100,000) : “Clean Assurance” for Routine surgeries
Applicable scenarios: General surgery (laparoscopic cholecystectomy), obstetrics and gynecology (cesarean section), ophthalmology (phacoemulsification for cataracts), and other routine surgeries. Although the cleanliness requirement is slightly lower, it is necessary to avoid contamination of the surgical incision by dust, Staphylococcus aureus and Pseudomonas aeruginosa carried by droplets from medical staff.
Application advantages
Compared with traditional HEPA filters, the dynamic air pressure adaptive function of liquid trough filters can maintain the supply air velocity stably at 0.25-0.3m/s. Even if the airflow is disturbed due to the movement of personnel and instruments during the operation, it can still form an “air barrier” to prevent external contaminated air from entering the surgical area. Meanwhile, its service life can reach over two years (while traditional filters only last for 6 to 12 months), reducing the frequency of filter replacement and saving 3 to 4 operating room shutdowns for maintenance each year, ensuring the continuity of surgical arrangements.
Ii. Intensive Care Unit (ICU) : The “Air Shield” Protecting Immune-Vulnerable Populations
Critically ill patients admitted to the ICU (such as those with shock, multiple organ failure, and extensive burns) have weakened immune functions and are vulnerable to airborne pathogens (such as the novel coronavirus, influenza virus, and Acinetobacter baumannii). Therefore, the liquid tank filter needs to take into account both “clean protection” and “environmental adaptation”.
1. Protective isolation ward (Burn ICU/Transplant ICU) : A “sterile space” for vulnerable patients
Core requirement: To create a one-way clean environment for patients with skin barrier damage (extensive burns) and immunosuppression (after organ transplantation), to prevent external air pollutants from entering the ward and reduce the risk of infection.
Application scenarios
The “top supply and bottom return” ventilation system is adopted, and liquid tank high-efficiency filters are installed on the top of the ward. Triple purification is achieved through a multi-layer filtration structure.
The pre-filter layer (primary filter material) intercepts large particles of dust ≥5μm, reducing the load on the high-efficiency filter material.
The high-efficiency filter layer (PTFE-coated material) intercepts virus particles and bacteria ranging from 0.1 to 0.3μm, with a filtration efficiency of ≥99.999%.
The activated carbon adsorption layer removes the unpleasant odor of wound secretions and residual disinfectants (such as the smell of chlorine-containing disinfectants) in the ward, enhancing the comfort of patients.
Data support: After the installation of liquid tank filters in a certain burn ICU, the concentration of 0.5μm particles in the ward was ≤1000 particles /m³, and the concentration of air bacteria was ≤2cfu/30min · φ90mm petri dishes. The incidence of hospital-acquired pneumonia (VAP) in patients decreased from 19.2% to 5.7%.
2. Infectious Disease Negative Pressure Ward (COVID-19 ICU/Tuberculosis ICU) : A “Safe Exit” to Block the Spread of Pathogens
Core requirement: For patients with respiratory infectious diseases, a negative pressure environment is needed to prevent the spread of pathogens to external areas. The filter must have the capabilities of “high-efficiency exhaust purification” and “anti-disinfection corrosion”.
Application logic
Liquid trough high-efficiency filters (upgraded to ULPA ultra-high-efficiency filters in some scenarios) are installed at the exhaust outlets of negative pressure wards. The chemics-resistant sealant (capable of withoperating in pH 2-12 environments and temperatures ranging from -20 ° C to 80 ° C) can adapt to frequent disinfection operations in the wards (such as peracetic acid fumigation and chlorine-containing disinfectant spraying). Avoid the leakage of pathogens due to the aging and cracking of the sealant. Meanwhile, the filter’s interception efficiency for 0.1μm virus particles is ≥99.999%, ensuring that the air discharged from the ward is strictly purified, free of pathogen residue, and protecting the safety of medical staff and the external environment.
Iii. Pharmacy Purification Area: The “Clean Defense Line” Ensuring Drug Quality
The purification areas of the pharmacy department (Intravenous Admixture Service (PIVAS), sterile drug production rooms, and drug storage rooms) need to control air particles and microorganisms to prevent drug contamination, which could lead to reduced efficacy or safety risks. The “high-precision filtration” and “stable operation” characteristics of liquid tank filters are crucial in such scenarios.
1. Intravenous Admixture Service (PIVAS) : The “Aseptic Prerequisite” for Precise Admixture
The core requirement is that the preparation process of intravenous infusion (chemotherapy drugs, antibiotics, nutritional solutions) should be carried out in a sterile environment to avoid contamination of the liquid by air particles and bacteria and prevent infusion reactions in patients (such as fever and allergy).
Application scenarios
In the biosafety cabinets and horizontal laminar flow tables of PIVAS, liquid tank high-efficiency filters are installed. Their detachable structure makes maintenance and replacement convenient. When the resistance of the filter material reaches the set value (such as 250Pa), staff can quickly remove the filter for replacement without stopping the entire preparation system, ensuring the efficiency of infusion preparation. Meanwhile, the zero-leakage sealing design ensures that 100% of the air in the mixing operation area is filtered, preventing unclean air from entering the mixing area and contaminating the liquid medicine. After the application of PIVAS in a certain tertiary hospital, the particle contamination rate during the infusion preparation process dropped from 8.3% to 0.9%, and no adverse infusion reactions caused by drug liquid contamination occurred again.
2. Sterile drug production/storage room (Injection/Vaccine Workshop) : The “Stable Guarantee” of drug quality
Core requirements: The production and storage of sterile drugs (such as injections and vaccines) must comply with GMP standards. The concentration of air particles (0.5μm) should be controlled at ≤3500 particles /m³ (in a 10,000-level clean area), and no microorganisms should be detected to prevent the drugs from being contaminated, which may affect their efficacy or cause safety accidents.
Application advantages
The long service life (up to more than 2 years in an ISO 5-level clean environment) and low maintenance cost of the liquid tank high-efficiency filter can reduce the number of shutdowns for maintenance in the pharmaceutical production room and ensure the continuity of production. Meanwhile, its stable filtration performance can ensure that the particles and microorganisms in the air are always controlled within the standard range. After a certain vaccine manufacturing enterprise installed the liquid tank filter, the qualification rate of sterile drug production increased from 97.5% to 99.8%, and there were no more batch scrapping problems caused by air pollution.
Iv. Other Special purification Areas: Precisely tailored to specific requirements
Reproductive Medicine Center (In Vitro Fertilization Laboratory) : “Sterile Environment” for embryo Culture
The applicable scenarios include in vitro embryo culture, embryo transfer and other operations. The concentration of airborne particles (0.5μm) in the laboratory should be controlled at ≤350 particles /m³ (in a Class 100 clean area), and no microorganisms should be detected in the air to prevent embryo contamination and the failure of culture.
Application value: The zero-leakage seal and ultra-high filtration accuracy of the liquid tank filter can ensure that the air around the embryo incubator is 100% sterile. After its application in a certain reproductive medicine center, the embryo implantation rate increased from 38.5% to 49.2%.
2. Pathology Section Laboratory (Molecular Pathology Area) : The “Clean Foundation” for Precise Detection
Core requirement: Molecular pathological testing (such as gene sequencing and PCR testing) should avoid nucleic acid contamination in the air to prevent false positive test results.
Application logic: A liquid tank high-efficiency filter was installed in the fume hood of the laboratory. By effectively intercepting nucleic acid fragments in the air, it ensured a clean testing environment. After application in a certain pathology department, the false positive rate of nucleic acid testing dropped from 5.3% to 0.8%.
