The temperature of an operating room (OR) is often noticeably cool, an observation that can be startling for patients preparing for surgery. This chill is a highly controlled environmental factor. The specific temperature and air quality within the surgical suite are meticulously managed variables, deliberately chosen to optimize conditions for the procedure itself. This precise climate control supports the complex work of the surgical team and maintains a sterile field.
Typical Temperature Range and Regulatory Standards
The ambient temperature within a surgical operating room is precisely regulated according to national guidelines, typically falling between 68°F and 75°F (20°C to 24°C). This range is mandated by professional organizations such as the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) and the Association of periOperative Registered Nurses (AORN). ASHRAE Standard 170 defines the parameters for both temperature and relative humidity in healthcare facilities. The temperature can be adjusted within the allowed range by the surgical team to suit the specific requirements of the procedure. For certain lengthy or complex operations, such as cardiac surgery, the temperature may be lowered toward the bottom of the range or even slightly below, supporting the team’s performance.
Primary Medical Reasons for Cooling the OR
The primary motivation for maintaining a cooler OR environment is the reduction of infection risk. Lower temperatures inhibit the proliferation of microorganisms, as bacteria tend to thrive in warmer conditions. By slowing the growth of potential pathogens, the cool air contributes to a more sterile environment, minimizing the risk of surgical site infections.
A cooler room also directly supports the surgical staff, who wear multiple layers of clothing, including scrubs, sterile gowns, and sometimes lead shielding. Surgical procedures are physically demanding, and the cooler temperature prevents the staff from overheating and perspiring. Perspiration can lead to fatigue, reduced focus, and an increased risk of contaminating the sterile field.
The cool temperature is also beneficial for the sophisticated equipment used in surgery. Many sensitive monitoring devices, cameras, and electronics generate heat and function optimally within a regulated, cooler climate. Preventing overheating ensures the consistent accuracy and reliability of this machinery throughout the procedure.
Patient Thermal Management During Surgery
While the cool environment is necessary for infection control and staff performance, it poses a challenge to maintaining the patient’s normal body temperature. Patients under anesthesia are prone to developing unintended perioperative hypothermia (UPH), defined as a core body temperature below 96.8°F (36°C). Anesthesia impairs the body’s natural ability to regulate its temperature, and exposure to the cool OR air causes heat loss through radiation and convection.
Perioperative hypothermia is a concern because it can lead to several adverse outcomes, including delayed wound healing, increased risk of surgical site infections, and adverse cardiac events. Even a mild drop in core temperature can increase the risk of bleeding and necessitate a greater need for blood transfusions. Therefore, a dedicated focus on patient warming is a mandatory part of surgical care.
To counteract the cold air, active warming techniques are employed throughout the patient’s time in the perioperative area. Forced-air warming devices, often referred to by the brand name Bair Hugger, are commonly used to circulate warm air over the patient’s body. Additional measures include the use of warmed intravenous (IV) fluids and irrigation fluids, which prevent the infusion of room-temperature liquids from further cooling the core body temperature. Passive measures, such as insulating the patient with blankets and thermal coverings, are also used to minimize heat loss.