The construction of a clean operating department must simultaneously meet the requirements of both hygienic standards and air cleanliness technical standards in three aspects: design, construction, and acceptance.

2.1.1 Controlling nosocomial infections should be a concept of comprehensive control, cutting off all contamination routes

It is not enough for only the operating room to be clean; the cleanliness requirement should be implemented throughout an area comprising the operating room and its necessary supporting auxiliary rooms. This area is the operating department, that is, the clean operating department.

Among all hospital departments, the surgical environment poses the greatest potential hazard, so the control requirements for the operating department and operating rooms should justifiably be the highest.

In order to facilitate achieving and maintaining the indoor environmental air quality requirements of the clean operating department and to eliminate interference from other departments, the clean operating department should preferably be a complete enclosed system.

The pollution sources leading to nosocomial infections in the operating room are shown in Table 2.1.

Table 2.1 Sources of Nosocomial Infection in the Operating Room

Infection Source Infection Route
Internal Patient's own infection caused by improper preoperative skin cleansing
External ① Direct contact with instruments, surfaces, or medical staff that have not been disinfected, have been incompletely disinfected, or have been re-contaminated by air ② Dissemination of droplets produced by hospital personnel who have been in contact with patients ③ Droplets and dust particles in the air transmitting microorganisms to the surgical incision ④ Immunocompromised patients inhaling bacteria-laden air

The relationship of personnel and articles in the clean operating department to nosocomial infection is shown in Tables 2.2 and 2.3.

Table 2.2 Classification of Personnel in the Clean Operating Department

Composition Nature Clean/Contaminated Category Requirements
Operating surgeon, scrub nurse Directly performing surgical operations, passing surgical instruments Clean personnel High hygiene standard for room entry
General physicians, circulating nurses Not directly performing surgical operations, large range of movement, greater impact Clean personnel Relatively high hygiene standard for room entry
Interns, visitors Treated as general medical staff Clean personnel Relatively high hygiene standard for room entry
Patients Often carriers of bacteria, and may bring contaminants from wards and corridors Quasi-clean personnel Disinfected, wiped down, and changed into gowns, but generally not subjected to strict hygienic treatment

Table 2.3 Classification of Articles in the Clean Operating Department

Composition Nature Clean/Contaminated Category Requirements
Surgical gowns, surgical drapes, gloves, surgical instruments, dressings, etc. In direct contact with wounds Clean articles Sterilized by autoclaving
Surgical instruments and equipment, articles after cleaning but before sterilization Not in contact with wounds; contact occurs only after disinfection and sterilization Quasi-clean articles Cleaning
Post-operative instruments, dressings, surgical waste Often carry large numbers of bacteria, causing contamination of personnel and air Contaminated articles Transported in isolation as much as possible

【Reference】 ① The composition proportions of nosocomial infection sites are shown in Table 2.4 (based on the 1998–1999 surveillance data of the National Nosocomial Infection Surveillance Network). As can be seen from the table, for surgery, lower respiratory tract and wound infections account for more than half of all infections.

Table 2.4　Composition Ratio of Nosocomial Infection Sites (%)

Department Lower respiratory tract Gastrointestinal tract Postoperative wounds Skin and soft tissue Urinary tract Blood Others
Internal medicine 35.5 13.5 0.4 4.0 12.8 1.4 32.4
Surgery 26.9 7.8 25.7 9.0 11.1 1.3 18.2
Pediatrics 24.1 25.2 1.4 7.0 1.7 0.8 39.8
Gynecology 12.4 8.4 11.1 1.6 24.1 0.2 42.2
Obstetrics 16.7 5.8 13.4 13.4 12.2 0.7 37.7
ENT 14.5 10.0 14.3 4.7 2.9 0.08 53.5
Total 30.4 11.9 10.1 6.4 10.9 1.2 29.1

② The distribution composition proportions of common pathogens in nosocomial infections at different sites are shown in Table 2.5 (same source as Table 2.4).

Table 2.5　Distribution Composition Ratio of Common Pathogens in Nosocomial Infections at Different Sites (%)

Pathogen Infection site Infection site Infection site Infection site Infection site Infection site Infection site
Lower respiratory tract Postoperative wounds Urinary tract Gastrointestinal tract Blood Skin and soft tissue Other sites
Escherichia coli 5.0 16.8 21.5 6.9 16.6 9.3 7.5
Pseudomonas aeruginosa 11.2 10.0 — — 5.5 13.2 —
Enterobacter spp. — 9.6 8.7 5.2 — 8.6 6.5
Klebsiella spp. 8.5 6.1 — — 6.6 — —
Staphylococcus aureus 8.7 11.6 — — 8.3 20.4 6.9
Staphylococcus epidermidis 5.9 5.9 5.1 5.9 11.5 7.9 16.9
Candida albicans 7.9 — 5.8 13.6 — — 8.0
Enterococcus — — 5.5 — — — —
Fungi 16.0 2.6 21.9 50.5 10.7 5.2 18.1

2.1.2　Infection control is also a whole-process control concept, requiring that the entire surgical process be under control

(1) General hygiene disinfection and sterilization measures only provide control at the starting point; in the entire surgical process thereafter, as personnel move about—and especially as a result of the air supplied by air conditioning—the aseptic state of the room that has just been disinfected is immediately destroyed.

Practice has proven that, at a time when medical technology and equipment have all made great strides while the air condition alone has deteriorated (see Tables 2.6–2.8), the airborne route is an important route of infection; in particular, since operating rooms in the future cannot possibly keep air conditioning out, air-conditioning air by itself is an enormous source of microorganisms.

Table 2.6　Counting Concentrations of Atmospheric Dust in Several Typical Regions Abroad

Region Dust concentration (≥0.5μm)/(particles/L) Region Dust concentration (≥0.5μm)/(particles/L)
Rural area $3times10^4$ Polluted area $177times10^4$
Large city $12.5times10^4$ Ordinary area $17.7times10^4$
Industrial center $25times10^4$ Clean area $3.5times10^4$
Rural area $10times10^4$ For cleanroom design $17.5times10^4$
Suburb $20times10^4$ Extremely clean $0.19times10^4$
Urban area $50times10^4$ Extremely polluted $56times10^4$

Table 2.7　Zoned data on atmospheric dust in China

Region Dust concentration (≥0.5μm)/(particles/L)
Non-industrial area or rural area $leqslant 1times10^{5}$
Urban suburbs $leqslant 2times10^{5}$
Within industrial cities $leqslant 3times10^{5}$

Table 2.8　Examples of outdoor atmospheric bacterial concentration measurements

Location Time Bacterial concentration　settled colonies/[count/(dish·h)] Bacterial concentration　airborne bacteria/(count/m³) Notes
Shanghai Xinhua Hospital 9:30～11:30 583 (6 times) 1 992 (3 times) Measured by Tongji University; most measurements were taken outside windows at heights above the second floor. The settled bacteria and airborne bacteria were not all measured at the same point. Airborne bacteria were sampled with a slit sampler
Shanghai Changzheng Hospital 7:30～10:14 714 (6 times) —
Shanghai Huashan Hospital 8:15～11:45 534 (8 times) 4 237 (8 times)
7:35～10:00 374 (8 times) 2 337 (5 times)
10:15～12:06 195 (5 times) 245 (4 times)
Shanghai Zhongshan Hospital 8:37～8:52 232 (1 time) 1 235 (1 time)
Water Supply and Drainage Laboratory, Tongji University, Shanghai 1504
Outdoors at Tianjin Health and Epidemic Prevention Station 400～1 740 Measured by the Epidemic Prevention Station of the Tianjin Municipal Health Bureau, sampled with a WOL-1 air microorganism sampler
Beining Park, Tianjin 620～1 340
Outdoors at Tianjin Workers' Hospital 1 640～2 760
Square in front of Tianjin Railway Station 5 120～13 600
Outside the Zhongyuan Company shopping mall, Tianjin (during business hours) 1 680～3 800

The whole-process control concept is shown in Table 2.9.

Table 2.9　Two concepts of aseptic control

Item Modern concept Past concept
Control concept Whole-process control, not merely the result of "the patient not being infected" Relying on drug control to achieve the result of "the patient not being infected"
Control requirements Control of the entire surgical process, cutting off all contamination routes (including air) to prevent bacteria from reaching the incision Relying on drugs to disinfect the environment, with patients taking large amounts of antibiotics
Control approach "Preventive" measures "Remedial" measures
Effect "Controlling the whole process" to prevent bacteria from entering the human body, with drugs as an auxiliary means, achieving the result of minimal injury to the patient Bacteria have already entered and damaged the human body, and infection is then controlled with drugs; this only reflects a "result", while the "control process" has already failed

【Reference】

① Data from the World Health Organization (WHO) point out: "If the total bacterial count is 700～1 800 per m³, there is a significant risk of airborne infection; if the total bacterial count is less than 180 per m³, this risk appears to be very small."

② According to investigation and research by British scholars over more than 30 years, statistics on postoperative infections from 6000 hip joint replacement surgeries show that when the bacterial concentration drops from 200 per m³ to 20 per m³, the infection rate can be reduced by half. For this lower limit of "20", some have also given 40, 30 or 10.

Figure 2.1 shows the results of the postoperative infection rate of hip joints. It is generally pointed out that when the bacterial concentration is reduced further, for example down to 5 /m³, the decrease in infection rate is no longer significant. It should be noted that the above bacterial concentrations are intraoperative data.

(2) Pathways of airborne infection in the operating room.

1) Incision and wound infection. Whether it is a surgical incision or a wound, it is surrounded by microbial aerosols from the very beginning. Microbial particles, whether deposited directly or coming into indirect contact with the incision or wound, may colonize, multiply, and cause infection on it. Even one of the most common airborne miscellaneous bacteria—Bacillus subtilis—has caused wound infections.

Figure 2.1　Postoperative infection rate of hip joint

It is also reported that the bacterial species isolated from wound exudates can all be collected from the air in the operating room. Biochemical classification was performed on the Escherichia coli from wound infections and the E. coli isolated from the operating room, and half of them were completely identical. Identification by colony and overall morphology proved that airborne microorganisms are an important source of wound-infecting bacteria.

Staphylococcus aureus, especially methicillin-resistant Staphylococcus aureus, can cause fulminant wound-surface infections.

【Reference】　It was once believed that airborne transmission of Pseudomonas aeruginosa caused by microbial aerosols was rather unlikely. However, since 2.9% Pseudomonas aeruginosa was detected in the ceiling dust of burn wards, and Pseudomonas aeruginosa has been repeatedly found in the air of burn wards, this view has been shaken.

2) Respiratory tract infection. Most pathogenic microorganisms can be transmitted through the air, causing respiratory tract infections.

The characteristics of respiratory tract infection are: fulminant onset, large infection area, and an infective dose far lower than that of other routes.

【Reference】

① A person must ingest 100 million tularemia bacilli to become infected, whereas inhaling only 10–50 of them can cause illness.

② For guinea pigs, the "respiratory median infective dose" of inhaled Legionella is only 5% of the intraperitoneal infective dose.

③ For humans, the "respiratory median infective dose" of inhaled adenovirus is only half of the "tissue culture median infective dose".

④ Infection can occur as long as a single Q fever rickettsia organism deposits in the respiratory tract.

3) Fungal infection. Since fungal spores drift about with great ease, the air in hospitals becomes the medium for their transmission. Therefore, fungal infection has become an important target of airborne infection.

Patients who have undergone organ transplantation, patients on long-term antibiotics and hormones, those receiving radiotherapy or chemotherapy, those with neutropenia, and those with various foreign bodies retained in the body after surgery—what these patients have in common is immunodeficiency and diminished defense function, which makes them highly prone to fungal infection. For example, filamentous fungal disease is mainly caused by inhaling airborne filamentous fungal spores or conidia.

Through contact with air contaminated by fungi, dressings, infusion apparatus, valves, pacemakers, artificial joints, intraocular lenses, and dialysis equipment become contaminated, which in turn leads to infection of patients.

【Reference】

① Contamination of the air supply system of an operating room by pigeon droppings caused three cases of Aspergillus fumigatus endocarditis.

② Contamination of the filter in the air supply system of an operating room caused two cases of Rhizopus arrhizus infection.

③ Decay of the wood beneath a cabinet dispersed large quantities of Penicillium conidia, causing infections in multiple people.

(3) Clean air technology not only has the function of preventing external bacteria from entering the operating room and of controlling airborne infection throughout the entire surgical process; the German medical and health community has also found that it is an effective means of preventing the massive proliferation of specific bacteria indoors after long-term disinfection has disrupted the balance of bacterial species.

2.1.3　For the quality of a clean operating department, the design, construction, and acceptance of the operating department are equally important

Good design without good construction will not do, and good construction without good design will not do either; even if both the design and the construction are good, it is necessary to Only through strict acceptance inspection, letting the data speak, can the reliability of the results be demonstrated, and only then can the operating department be put into use.