Mechanical ventilation system
The basis of cleanliness in a modern surgical suite is supply ventilation. Outdoor air or recirculated air is forced into the room through special filters.
A key defense mechanism is the creation of positive pressure. Clean air constantly escapes from the operating room through natural gaps. This pressure difference acts as an invisible shield: it physically prevents the penetration of contaminated air masses from adjacent surgical departments and corridors.
If the building is not equipped with centralized ventilation, mobile air purifiers (e.g., VOPR-1.5) are used. They effectively filter out dust and microorganisms fixed to it.
Ultraviolet irradiation
Bactericidal UV lamps are actively used for sterilization. They can be installed as:
- Ceiling-mounted or wall-mounted (stationary options).
- Floor-standing (mobile units, e.g., of the "Mayak" type).
The operating mode strictly depends on the radiator design. Conventional open lamps are turned on exclusively in the absence of people. However, there are models with special shields that block direct UV rays—their use is permitted even in the presence of the surgical team.
Aerosol purification method
Acts as a supplement or alternative to ultraviolet irradiation. The "Dezinfal" sprayer device is used for chemical air treatment.
A specific mixture is used as the bactericidal agent:
- 3% hydrogen peroxide solution ($H_2O_2$).
- 0.5% lactic acid solution.
Spraying is carried out in advance—ideally on the eve of scheduled surgery, or at least 2 hours before the operation starts, so that the suspension has time to settle and take effect.
Laminar airflow operating rooms
This is the gold standard for interventions with a high risk of infectious complications: organ transplantation (where patients receive immunosuppressants), artificial prosthesis implantation, and extensive burn surgery.
Features of the laminar system:
- Pressure and air exchange: Air is forced under a pressure of 0.2–0.3 atm, providing a colossal 500-fold exchange per hour.
- Multistage filtration: Outdoor air passes through a pre-filter, is forced by a fan, and is pushed through a primary high-efficiency filter (usually ceiling-mounted).
- Directed movement: A constant vertical or horizontal flow of sterile air is formed. It moves from top to bottom, carrying microorganisms away from the staff and patient, and is removed through openings in the perforated floor.
In older surgical suites where full ventilation reconstruction is impossible, isolation booths are installed. These are plastic or glass structures whose walls do not reach the floor. The filter ceiling creates a vertical laminar flow inside, which displaces contaminated air into the floor gaps.
Historical note: The Spray method
At the dawn of asepsis, the spray method (Spray) was used. Before and during surgery, a phenol solution was sprayed into the air using an atomizer. This destroyed airborne bacteria. The effectiveness of this crude but innovative approach was proven by a multiple-fold reduction in mortality from postoperative purulent complications.
Briefly: answers to topical questions
What air cleanliness classes are designated for surgical suite premises?
Three classes of air cleanliness are designated for the premises of the operating department depending on their purpose.
- Particularly clean (A) — operating rooms prepared for work.
- Clean (B) — pre-operation rooms, dressing rooms, and treatment rooms.
- Conditionally clean (C) — corridors adjacent to operating rooms.
Which microorganisms are the main causative agents of airborne surgical infection?
The main microorganisms indicated in sources in relation to the airborne environment and nosocomial surgical infection:
- Staphylococcus aureus (S. aureus) — a sanitary indicator microorganism of healthcare facility air.
- Hemolytic streptococci — sanitary indicator microorganisms associated with the human upper respiratory tract microflora.
- Staphylococcus — one of the main causative agents of hospital-acquired infection.
- Escherichia coli — one of the main causative agents of hospital-acquired infection.
- Proteus — one of the main causative agents of hospital-acquired infection.
- Klebsiella — one of the main causative agents of hospital-acquired infection.
- Pseudomonas aeruginosa — one of the main causative agents of hospital-acquired infection.
For nosocomial infection in a surgical hospital, sources indicate transmission routes via objects, air, and linens; this flora is characterized by high resistance to antibacterial agents.
How often should bacteriological air control be performed in the operating room?
Bacteriological control of air sterility in the operating room must be performed once a month. This type of routine general control is carried out by culturing materials to assess air bacterial contamination, as well as testing swabs from walls, ceilings, and medical devices.
What are the exact operating modes and exposure times for bactericidal irradiators in the surgical suite?
The cited sources indicate the operating modes of ultraviolet bactericidal lamps, but do not provide the exact exposure time for bactericidal irradiators in the surgical suite.
Operating modes:
- Conventional lamps — used in the absence of people.
- Lamps with special shields — protect against direct UV rays and can operate in the presence of people.
To remember the composition of the bactericidal aerosol, use the abbreviation PM: Peroxide (hydrogen peroxide 3%) + Milk (lactic acid 0.5%).
Class and exam questions
Why is it important to maintain positive pressure in the operating room?
Excess pressure creates a directed outward airflow through gaps. This prevents dirty air from corridors and adjacent rooms from penetrating the sterile zone.
Can quartz or germicidal lamps be turned on when people are in the operating room?
Conventional open lamps must not be used. In the presence of personnel, only emitters equipped with special protective shields are permitted to be turned on.
In which cases is an operating room with laminar airflow strictly required?
Such systems are necessary for surgeries with the highest risk of infection: organ transplantation, implant placement, and the treatment of extensive burns.
What else to study on this topic
- Physical principles of laminar airflow formation
- Design and filtration class of ceiling filters (HEPA filters)
- Safety precautions when working with open-type UV irradiators
- Assessment of microbiological air purity in the surgical suite
- Design features of isolation boxes for old buildings
Master the entire topic in the "General Surgery" course
This is a summary. The course covers everything tested in classes and exams.
- Full study guide on «Air sterilization in the operating room» and 3,335 more pages for this subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 70 video lessons on the subject
Other topics in the section "CHAPTER 2. ASEPSIS AND ANTISEPSIS"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.