Discrete room pressure drops predict door openings and contamination levels in the operating room setting

Abstract

BackgroundContamination of operating room air is associated with increased risk of surgical site infection. Door opening events occur often during surgery. The effect of door opening on room pressure and contamination is investigated, and detection of door opening events via a single internal barometric pressure sensor is demonstrated. MethodsA single barometric pressure sensor stationed in a corner away from the door was used to measure room pressure in a simulated OR with air flow conditions of 20 ACH and a positive pressure of approximately 7.5 Pa. A laser-based particle counter was used to measure particle levels during a series of 20 periodic door opening events. ResultsThe average (standard deviation) detected room pressure in the OR under positive pressure decreased by approximately 6.5 (1.2) Pa (p>3 × 10−17). When the door is closed the pressure returns. Initial airborne particle levels in the room were 36 (6) /ft3. 20 periodic door openings performed over 40 min. resulted in particle levels exceeding 200/ft3. ConclusionsOR barometric pressure decreases and recovers when the door to an OR under positive pressure is opened and closed and provides a detectable signal for passively monitoring and tracking door openings. The number of particles in the unoccupied OR increases as increasing numbers of door opening events occur.