Study: ORs with radiant air conditioning more comfortable than those with convection systems

Editor's Note

Radiant air conditioning systems (RAS) provide greater comfort for surgical patients than traditional convection air conditioning systems (CAS), according to a Japanese study detailed in Anesthesiology News December 3. 

According to the article, the study was conducted from November 2015 through March 2016 and involved 48 patients scheduled for laparoscopic surgeries—21 in a CAS-equipped OR and 27 in an RAS-equipped OR. Both rooms maintained a temperature of 25°C and 50% humidity from patient admission through the end of anesthesia. Patients' tympanic temperatures were continuously measured from pre-anesthetic induction until awakening. Thermal comfort was assessed using the Predicted Mean Vote (PMV) method. Key findings include:

• Thermal Comfort: Patients in RAS rooms experienced significantly lower minimum PMV scores, indicating greater comfort, compared to those in CAS rooms (P<0.0001).
• Temperature Stability: Tympanic temperature variations were notably less pronounced in the RAS group. For instance, at the end of surgery, RAS patients showed a mean temperature change of +0.081°C, compared to -0.527°C in the CAS group (P<0.005).
• Use of Warming Systems: Only 2 RAS patients required forced-air warming, compared to 17 CAS patients.

According to the article, convection systems cool the OR by funneling cold, clean air over the patient's body surface through vents located directly above the operating table. While effective at maintaining a cool environment, this direct airflow can make patients uncomfortably cold, often necessitating the use of patient warming systems. In contrast, RAS controls room temperature via radiation, using water passing through pipes in the walls and ceiling, thereby eliminating the need for direct air movement over the patient's body. This delivers equal temperature throughout the room, with researchers highlighting particular advantages for pediatric populations.