The Effect of Door Opening on Operating Room Positive Pressure and Airflow

Introduction: Operating room (OR) door openings and increased foot traffic during total joint arthroplasty (TJA) presents a concern for surgical site infection (SSI). Environmental controls such as positive pressure, air filtration, and the limitation of operating room traffic are all currently utilized methods to reduce the risk of SSI in TJA. We aimed to define: if OR positive pressure is defeated with door opening, how long it takes the room pressure to recover from a door opening event, if there any advantage to utilizing an inner substerile door to enter the OR, and to what extent does outside, unconditioned air enter the OR during a door opening event.

Methods: This observational study was performed during off-hours in 6 empty ORs normally utilized for TJA. Pressure data was recorded at the threshold of both the main and inner substerile door under several conditions. Testing was performed in triplicate to reduce bias. Airflow patterns were visualized with smoke studies to determine if outside air entered the OR with the main door open, the inner core door open, or both doors open together.

Results: The average time needed for OR pressure to recover from personnel entering through the main door, equipment being passed through the main door, or personnel entry through the inner core door was 14.11, 14.22, and 14.73 seconds, respectively. OR positive pressure was not defeated at any time point during single door opening, even with the main doors open for 30 seconds. Smoke studies confirmed that contaminated outside air did not enter the operating room during single door opening events. Contaminated air was visualized to enter the OR if greater than 1 door was open simultaneously.

Conclusion: OR personnel should be informed of the danger that simultaneous (>1) door opening poses to the sterile field and discouraged from such activity.