Surgical Infection Risk May Be Impacted By Operating Room Door Openings: Study

A new study suggests that there may be a connection between the level of traffic through an operating room and the risk of surgical infections, finding that the frequency of operating room doors opening may undermine steps taken to maintain a sterile environment. 

In a study published last week in the medical journal Orthopedics, researchers indicate that there is a significant relationship between operating room door openings and room pressure, calling for further research to determine whether post-surgical infections may be directly related to this loss of positive pressure.

Operating rooms are designed to maintain positive pressure, where the room pressure is greater than the surroundings, to keep airborne contaminants out of the room. This is done with special ventilation systems that force air out of the room when doors are opened. However, when doors are frequently opened, outside air may enter the operating room instead.

Researchers electronically monitored air pressure, comparing it against the number and length of door openings in operating rooms during nearly 200 knee and hips surgeries between March and June 2011 at the Johns Hopkins Bayview Medical Center in Baltimore. Electronic monitoring of heating, ventilating, and air conditioning systems is a part of infection control initiatives put in place in hospitals.

The medical staff and surgeons were unaware the data was being collected to ensure habits were not changed.

The study revealed that in 77 out of 191 cases, the door was opened long enough to allow the positive pressure to be defeated, allowing air to flow into the operating room. On average, the door was opened 9.5 times per surgery for an average of nearly 10 minutes. Researchers found for every 2.5 minute increase in operating time, the doors were opened one more additional time adding 6.9 seconds to the total open time.

The time with the door open significantly affected the minimum pressure recorded in the room, potentially allowing airborne bacteria to enter.

Despite the room being able to recover from the loss of pressure, it still put patients at risk of infection. Other studies have also shown that a high level of operating room traffic is related to higher bacterial counts.

The study also found the number of times the door was opened and the duration of openings was linked to the length of surgery, type of surgery and even surgeon. The research found the average operating time was 103 minutes, but ranged from 82 minutes to 182 minutes. There were 23 air exchanges per hour.

Infection data was also obtained from hospital infectious disease monitoring records. Researchers found of the 200 cases there was one knee infection and no hip infections. The doors also opened one fewer times in knee surgeries than hip surgeries.

Despite low infections rates, researchers said understanding the factors of frequent door openings and why it is happening will help find interventions for decreasing the foot traffic in and out of the operating room. Lowered foot traffic will translate to reduced infection risk overall.