On Monday, I got a text message from our hospital’s Chief of General Surgery at 6:40 AM that the operating rooms were in excess of 100° F. When the air temperature in the OR is too high, it is not only uncomfortable for the surgeons and OR staff who are all wearing surgical gowns, it is unsafe for the patients because of the risk of infection. When temperatures are too high, microorganisms grow. When the humidity is too high, condensation can develop on the ceilings and equipment resulting in non-sterile indoor “rain” on patients or instruments. If either the temperature or the humidity is too high, then the surgeons start sweating which is not only a distraction but no one wants drops of sweat falling into a patient’s open incision. Too cold is also bad, hypothermic patients are more likely to get wound infections. Because both too hot and too cold is dangerous, the CDC adopts the American Institute of Architects parameters for operating room ventilation:

Temperature: 68-73° F

Humidity: 30-60%

Air changes: 15 total air changes per hour and minimum 3 air changes of outdoor air per hour

Keeping a relatively narrow temperature and humidity range turns out to be more difficult than it might seem because of the relationship between temperature and humidity. For example, if a room is 68° F with 60% relative humidity (within parameter range) and you drop the temperature to 64° F, the relative humidity will rise to 68% (out of parameter range).

Operating rooms have visual alerts in a central location when the OR air temperature or humidity is out of the parameter range but these alerts are on monitors and if no one happens to be looking at the monitors, then the alerts go unnoticed.

When a hospital goes through a JCAHO (Joint Commission) site survey, the surveyors will make a bee-line for refrigerators and freezers to be sure that there are temperature logs being kept and alarms when there is a loss of power or refrigeration. However, no one ever thinks to have logs or alarms for the air temperature in an operating room.

So, on Monday morning, we moved as many procedures from the overheated primary OR area to an unaffected secondary OR area. However, when temperatures get to 110° F, many disposable supplies can be damaged and have to be thrown out and sterilized instrument sets need to be re-processed. Therefore, a number of surgeries had to be canceled at the last minute. Fortunately, although there was inconvenience, no patients were placed in jeopardy.

The best way to avoid excessive heat in the OR is to have multiple, redundant alerts. So, make sure that you have both audible alerts as well as visual alerts on the temperature monitors.  Also, arrange that the alerts trigger auto-pages to hospital administrative staff when OR temperature or humidity parameters are out of range.

I must have missed the class on HVAC systems in medical school.

December 21, 2016