Research ArticleThe Effect of Door Opening on Positive Pressure and Airflow in Operating RoomsWeiser, Mitchell C. MD, MEng; Shemesh, Shai MD; Chen, Darwin D. MD; Bronson, Michael J. MD; Moucha, Calin S. MDAuthor Information From Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY (Dr. Weiser) and the Icahn School of Medicine at Mount Sinai, New York, NY (Dr. Shemesh, Dr. Chen, Dr. Bronson, and Dr. Moucha). Correspondence to Dr. Weiser: email@example.com Dr. Weiser or an immediate family member serves as a paid consultant to Pacira Pharmaceuticals. Dr. Bronson or an immediate family member serves as a board member, owner, officer, or committee member of the Arthritis Foundation. Dr. Moucha or an immediate family member is a member of a speakers’ bureau or has made paid presentations on behalf of 3M. Neither of the following authors nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Shemesh and Dr. Chen. The authors would like to acknowledge that this study was made possible by a clinical research grant from the LeFrak Family Foundation. The videos that accompany this article are online at http://links.lww.com/JAAOS/A82, http://links.lww.com/JAAOS/A83, and http://links.lww.com/JAAOS/A84. Journal of the American Academy of Orthopaedic Surgeons: March 1, 2018 - Volume 26 - Issue 5 - p e105-e113 doi: 10.5435/JAAOS-D-16-00891 SDC Metrics Abstract Introduction: Door openings and increased foot traffic in operating rooms (ORs) during total joint arthroplasty are thought to increase the risk of surgical site infection. Methods: Digital manometers were used to collect pressure data during off-hours at the thresholds of both the outer door (ie, the door to the common OR hallway) and the inner substerile door, which opens to the substerile hallway, of six empty ORs used for total joint arthroplasty. Airflow patterns were visualized with smoke studies to determine whether outside air entered the ORs during single or multiple door openings. Data were analyzed using the Student t-test and one-way analysis of variance. Results: Positive pressure was not defeated during any door-opening event. The average time for recovery of the initial pressurization in the OR regardless of the door used was between 14 and 15 seconds (P = 0.462). No differences in the degree of room depressurization were noted between entry of personnel through the outer door, passing of a surgical tray through the outer door, and entry of personnel through the inner door (P = 0.312). Smoke studies confirmed that no contaminated outside air entered the OR with single door opening. Outside air entered the OR if two doors were open simultaneously. Conclusion: Single door opening does not defeat OR positive pressure, but simultaneous opening of two doors allows contaminated air to flow into the OR. OR traffic should continue to be limited during surgical procedures. OR personnel should be educated about the danger to the sterile field that can result from simultaneous door openings and should be discouraged from such activity. Copyright 2018 by the American Academy of Orthopaedic Surgeons.