Designing the OR Around the People in It: A Human Factors Approach to SSI Prevention

Surgical site infections (SSIs) are a problem we have not solved. We have known the basics for decades. Give the right antibiotic at the right time. Prep the skin properly. Keep the patient warm. Limit door openings. Watch the air. And yet SSI rates have barely moved in many service lines, with roughly 160,000 to 300,000 still occurring in U.S. hospitals every year.

The question I keep hearing from quality leaders is: why doesn’t the bundle work the way it’s supposed to?

The answer is rarely that surgeons and nurses do not care. It is almost always the case that the system around them makes the right thing harder than it should be. That is the territory of human factors engineering, and it’s where the next real gains in SSI reduction will come from.

The bundle is real. The execution is the problem.

Most SSI bundles look reasonable on paper. CHG-alcohol prep, clipper-only hair removal, weight-based prophylaxis with appropriate redosing, normothermia, glycemic control, traffic control, and increasingly, air disinfection in the OR. The issue is that each of those elements depends on a person remembering, deciding, or reacting at the right moment, often during a case when their attention is correctly focused elsewhere. Antibiotic redosing is a classic example. The evidence is clear that prolonged cases need a second dose. Compliance studies still show that this is missed 20 to 40 percent of the time, depending on the institution. You cannot lecture your way out of that. The fix is in the system.

What Do Human Factors Mean In the OR?

Human factors engineering (HFE) treats the OR as a system of people, equipment, environment, and workflow, and asks where in that system errors are more likely to occur. The discipline borrows heavily from aviation and other settings where individual heroics cannot serve as a safety net.

Three principles tend to matter most for SSI work.

• First, make the safe action the easy action. If the right CHG applicator is not within the prep nurse’s arm’s reach, prep technique starts to drift. If the antibiotic timing prompt is buried in a tab nobody clicks, it gets missed.
• Second, reduce reliance on memory and vigilance. Checklists, forcing functions, and visual cues do the remembering so the team can focus on the case. The WHO surgical safety checklist is the obvious example, and the data on its effects are still among the strongest we have.
• Third, engineer the environment, not just the behavior. This is the part that often gets skipped. Temperature, humidity, traffic, lighting, and air quality are all part of the SSI equation, and none of them respond to staff training. That third point is where air disinfection earns its place in the bundle.

Air Is Part of the System

For a long time, OR airborne contamination was treated as a fixed property of the room. You had your laminar flow, your air changes per hour, your terminal HEPA filtration, and that was the floor. Whatever fell into the wound from the air was considered unavoidable.

That assumption no longer holds. Studies using particle counting and microbial sampling have shown that intraoperative bioburden in the air rises sharply with door openings, staff movement, and case duration, and that traditional ventilation often cannot keep up. Higher airborne CFU counts correlate with higher wound contamination, particularly in orthopedic and cardiac cases where the consequences of infection are severe.

Adding active air disinfection to the OR, layered on top of existing HVAC, addresses the part of the problem that no amount of staff training or door discipline will fully solve. It is a passive intervention. It works whether the team remembers it or not. From a human factor’s standpoint, that is the kind of control you want, because its effectiveness does not depend on anyone’s vigilance during the case. It also pairs well with the behavioral elements of the bundle. Traffic control programs reduce door openings, which reduces particle introduction. Air disinfection handles what gets in anyway. The two work together rather than competing for staff attention.

What This Looks Like in Practice

Hospitals that have made real progress in reducing SSI rates tend to follow a pattern. They stop treating the bundle as a checklist to enforce and start treating it as a system to design. Antibiotic timing is automated where possible. Prep supplies are standardized and pre-positioned. Warming protocols start in pre-op rather than at incision. Door-opening data is reviewed monthly, not annually. And the air around the wound is actively managed instead of assumed to be clean enough. None of this is about working harder. It is about removing the points where the current system asks people to be perfect.

The Takeaway for OR Leaders

If your SSI rates are stuck, the next move is probably not another in-service. It is a walk through the OR with a human factors lens, asking where the system makes the right action difficult and where you are still relying on memory or vigilance to hold the line. Air disinfection belongs on that list, alongside the more familiar elements of the bundle, because it addresses a contamination source that behavioral interventions cannot reach. The goal is an OR where doing the right thing is the path of least resistance for everyone in the room. That is what human factors engineering offers, and that is where the next generation of SSI prevention is going.