title: Shutting down operating theater ventilation when the theater is not in use: infection control and environmental aspects.
abstract: OBJECTIVE
  In hospital operating rooms (ORs), specially conditioned air is supplied to protect patients from airborne agents that may cause infections. This study investigated whether it is hygienically safe to shut down the air supply at night if measures are taken to ensure a timely restart before surgery is performed.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  Neurosurgical OR of a German university hospital.
  
  
  METHODS
  The ventilation system was switched off and restarted after 10 hours. Particles suspended in the air near the operating table were counted, OR temperature was measured, and settle plates were exposed and incubated.
  
  
  RESULTS
  In 13 investigations, a median of 1.3 x 10(4) particles 0.5 microm/m3 or greater (range, 5.8 x 10(3) to 1.1 x 10(5)) were documented immediately after restart in the morning. After 10 minutes and subsequently, no test showed a particle count exceeding the threshold limit of 1.0 x 10(4) particles 0.5 microm/m3 or greater recommended by the German Society of Hygiene and Microbiology. Only a few colony-forming units (CFU) were detected per settle plate (median, 0 CFU/60 cm2; range, 0 to 8) and OR temperatures quickly reached normal levels.
  
  
  CONCLUSIONS
  Shutting down OR ventilation during off-duty periods does not appear to result in an unacceptably high particle count or microbial contamination of the OR air shortly after the system is restarted. Because substantial energy and cost savings are likely, this should be considered in hygienically safe heating, ventilation, and air conditioning systems. However, normal ventilation should be established at least 30 minutes before surgical activity.
authors.affiliation: Institute of Environmental Medicine and Hospital Epidemiology, Hugstetter Str. 55, 79106, Freiburg, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Dettenkofer
authors.forename: M
authors.initials: M
authors.lastname: Scherrer
authors.forename: V
authors.initials: V
authors.lastname: Hoch
authors.forename: H
authors.initials: H
authors.lastname: Glaser
authors.forename: G
authors.initials: G
authors.lastname: Schwarzer
authors.forename: J
authors.initials: J
authors.lastname: Zentner
authors.forename: E D
authors.initials: ED
authors.lastname: Daschner
mesh_terms: D000046:Academic Medical Centers; D000391:Air Microbiology / Q000592:standards*; D015169:Colony Count, Microbial; D004784:Environmental Monitoring / Q000379:methods*; D005858:Germany; D006801:Humans; D017053:Infection Control / Q000379:methods*; D008284:Maintenance and Engineering, Hospital / Q000379:methods*; D009873:Operating Rooms / Q000592:standards*; D010316:Particle Size; D013530:Surgical Wound Infection / Q000517:prevention & control*; D014691:Ventilation / Q000295:instrumentation / Q000379:methods*