Can Cleaner Air in the Operating Room Protect Patients from Infection?

As the superbug crisis worsens and the population ages, it’s a question more researchers and — more hospitals — are taking seriously.

Bacterial infections that once were easily treated have become grave, even lethal, and nowhere is the risk higher than in the operating theatre. Surgical-site infections rank among the most common healthcare-associated infections, and those acquired via orthopaedic surgery, such as total joint replacement procedures, are among the most painful, expensive, and serious.

“Surgical site infection is disastrous in orthopaedic practice, as it is difficult to rid the bone and joint of the infection,” a Saudi research team affirmed in International Surgery.

Patients infected during surgery are 60% more likely to be admitted to the intensive care unit and five times more likely to be readmitted to the hospital after discharge, compared to uninfected patients. The cost for a single Methicillin-Resistant Staphylococcus aureus (MRSA) infection acquired during surgery can reach $40,000.

Many infected patients face additional surgery and suffer “excruciating agony,” as documented by British researchers.

Others die from their infections. For prosthetic joint infections, the mortality rate is 2% to 7%, with a five-year survival rate worse than with many cancers.

And as European and American populations age, surgical procedures — and the lethal infections that can result — will only become more common. By 2030, the number of prosthetic joint surgeries is expected to exceed 3.8 million annually in the United States alone. By that same year, the total number of infections acquired during prosthetic joint surgery could approach 1 million.

In response to the infection crisis, hospitals are ramping up efforts to keep operating rooms sterile. They are restricting staff flow in the operating theatre, more effectively sterilizing surgical clothing and operating theatre surfaces, and demanding better hand hygiene among doctors and nurses. They are using special skin-prep procedures, post-op dressings, and antimicrobial sutures and are more carefully controlling antibiotic prescriptions.

And yet, dangerous microbes — MRSA, Enterococcus, Acinetobacter, and others — continue to penetrate surgical wounds.

What more can hospitals do?

They can sterilize the air.

Clean Air Is Safer for Patients

An American research team, writing about joint-replacement surgery in the American Journal of Infection Control, recently asked: “Is it time to reassess microbial contamination of the operating room air as a risk factor for surgical site infection?”

The answer: a resounding “yes.”

In fact, the World Health Organization has established limitations for microbial contamination in operating rooms, as have several European Union countries.

Airborne pathogens are a well-documented source of surgical site infections, accounting for about 20% of infections acquired in hospitals, including in the operating theatre.

The more contaminated the air, studies show, the higher the risk of infection.

For example, British researchers who analyzed joint-replacement surgery and infection outcomes at 15 hospitals reported a correlation between air contamination and the sepsis rate among patients.

“By far the largest proportion of bacteria found in the wound after the prosthesis had been inserted reached it by the airborne route,” the authors concluded.

And in a study of hip- and knee replacement operations, University of Glasgow researchers estimated 30% of bacteria in wounds “fell directly from the air.” The rest “presumably fell on to other surfaces” — scalpels or surgical gloves, for example — and were transferred indirectly to the wound.

Despite all the precautions hospitals take, infectious particles have numerous pathways to the operating-room air.

Bacterial and viral particles can be launched airborne when an infected patient — inside or outside the hospital — sneezes, coughs, talks, or even breathes. The particles can then travel via air currents throughout the building, into the operating room, and ultimately into the surgical wound. Pathogens shed from the skin of infected patients can make the same journey.

But air disinfection in the operating theatre can disrupt this chain of events.

“By targeting the air, we target the vector that causes surface contamination,” explains Ojan Assadian M.D., president of the Austrian Society for Infection Control.

In other words, when the air is clean, dangerous microbes can’t settle on surgical instruments or burrow into wounds.

Plasma Technology: A More Effective Way to Clean Operating Theatre Air

Though surgical patients are particularly vulnerable to infection, operating theatre air is often “no cleaner than the air in other units,” according to authors writing in Infection Control Today.

Air disinfection has been largely overlooked as a defence against operating theatre-acquired infection; for decades, experts have instead emphasized hand hygiene and surface cleaning.

But three facts have changed the calculus:


  • The superbug crisis has become increasingly dire.

  • Hand hygiene and surface cleaning have proven woefully inadequate at halting the spread of infection; in fact, the World Health Organization describes hospital hand-hygiene compliance as “abysmally low.”

  • New technology has made air disinfection dramatically more effective.


Of course, hand hygiene and surface cleaning remain critical strategies; hospitals cannot let up on campaigns to improve both, especially in surgical situations. But the rise of antibiotic-resistant bacteria has raised the stakes. As Dr. Assadian notes, “realistically, we must also rethink our approach and look into additional strategies.”

For decades, methods of air disinfection have been limited. Hospitals have relied on preventive maintenance of air handling systems; control of temperature, humidity, and air pressure; and HEPA filtration.

But HEPA filters only trap pathogens; they do not kill them. What’s more, viable pathogens caught in a HEPA filter can colonize, presenting a safety hazard for maintenance staff handling the filters.

Newer, more aggressive methods have shown promise but also have shortcomings. For example, ultraviolet germicidal irradiation can kill airborne pathogens, but UV lamps also can promote the formation of cataracts and other eye conditions. Misting hydrogen peroxide, while also useful for controlling infection, can irritate or burn a patient’s skin and corrode surfaces and instruments.

Notably, these solutions disinfect air on a temporary basis only, whereas pathogens are continually entering the operating theatre air.

For all these reasons, hospitals have been turning to ultra-low energy plasma technology that can disinfect air safely, 24 hours a day, with no human effort.

Deployed in numerous European hospitals, portable air disinfection units using plasma technology can sit unobtrusively in any operating theatre and work continually to eradicate airborne bacterial and viral particles.

Thus far, studies have demonstrated significant benefits: reduced respiratory infections, personnel sick leave, and rates of severe infectious outbreaks.

Can the same technology reduce surgical-site infections?

Infection-control experts in Sweden believe so and have launched the first double-blind, randomized, controlled trial to test this premise.

Conducted by Sweden’s Karolinska Institute, the study includes nearly all patients undergoing orthopaedic surgery at six Swedish hospitals over a three-year period. Patients are eligible if their surgery lasts at least 30 minutes. Novaerus Protect 800 was chosen by the Karolinska Institute to facilitate the study, under the hypothesis that its patented plasma technology will significantly reduce the incidence of surgical site infections (SSIs).

Of course, orthopaedic patients are not the only ones vulnerable to operating theatre-acquired infection. A U.S. research team, arguing in favour of “innovative strategies” for operating theatre air disinfection, noted that in the modern medical environment, virtually all surgical disciplines use implanted biomedical devices.

“Implants have been documented to be at high risk for intraoperative contamination,” the authors wrote in the American Journal of Infection Control.

The Human Cost of Surgical Site Infection

Studies on surgical site infections are packed with worrisome statistics — about hospital readmission rates, mortality rates, and economic costs. But while reading these studies, it’s easy to overlook the patient suffering that stems from operating theatre-acquired infections.

A British research team, however, delved into the human cost of surgical-site infection, conducting in-depth interviews with patients at three hospitals.

“This wound has taken over my life,” one patient told researchers. Another said: “I thought I was never going to get over it. It just seemed to go on and on.”

The epidemic of surgical-site infections will go on and on, too, unless hospitals escalate infection-control efforts in the operating theatre.

These efforts must include cleaning the air.

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