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Radiant Beats Convection Air Conditioning Systems for Operating Theatre Comfort

A study from Japan has found that operating theatres using radiant air conditioning systems (RAS) provide greater comfort for patients than traditional convection systems.

 

Radiant Beats Convection Air Conditioning Systems for Operating Room Comfort

Maintaining a consistent room temperature is an important component of a comfortable operating [theatre] (OR) environment. A popular approach to cooling the OR uses a convection air conditioning system (CAS). CAS technology funnels cold, clean air over the patient’s body surface via a vent located directly above the operating table. The patient is cooled via convection as air passes over their body. However, because patients are subjected to the direct flow of air, sometimes they can become uncomfortably cold, thus requiring the use of a patient warming system to correct the temperature.

RAS technology, in contrast, warms or cools the room via water passing through pipes located in the walls and/or ceiling. This system controls room temperature via radiation, eliminating the need for a direct flow of air across the patient’s body.

Yoshimi Inagaki, MD, and colleagues from Tottori University Hospital, in Yonago, Japan, studied the effect of the two systems on maintaining a consistent, comfortable OR environment. Their data were presented at the 70th PostGraduate Assembly in Anesthesiology.

Monitoring the Effect of Temperature Variations

The study was conducted from November 2015 through March 2016. During this period, 21 patients were admitted to the OR that used CAS and 27 to the OR that used RAS; all patients were scheduled for laparoscopic surgeries. In both rooms, temperature and humidity were maintained at 25°C and 50%, respectively, from the time of patient admission through the end of anesthesia. The patients’ tympanic temperature was measured continuously from preanesthetic induction through waking from anesthesia. The thermal comfort of the patient was determined by using the Predicted Mean Vote (PMV) method.

The investigators found that minimum PMV scores—meaning the patient was feeling cool—were significantly lower with the RAS than with the CAS (P<0.0001) (Table 1). Additionally, changes in tympanic temperature from baseline were significantly fewer with the RAS than with the CAS (Table 2). Only two of the RAS patients required forced-air warming, versus 17 in the CAS group.

 

Table 1. Tympanic Temperature Variation by System
CAS Patients, mean (SD) RAS Patients, mean (SD)
PMV –0.058 (0.393) °C –1.462 (0.630) °C
CAS, convection air conditioning system; PMV, Predicted Mean Vote; RAS, radiant air conditioning system

 

Table 2. Time-Related Temperature Change by System
PMV Time Intervals CAS Patients, mean (SD) RAS Patients, mean (SD)
60 minutes after admission to OR (P<0.01) –0.273 (0.212) ??°C –0.081 (0.156) °C
At 120 minutes (P<0.001) –0.520 (0.365) °C –0.075 (0.262) °C
At 180 minutes (P<0.005) –0.520 (0.376) °C –0.047 (0.366) °C
At end of surgery (P<0.005) –0.527 (0.559) °C 0.081 (0.542) °C
CAS, convection air conditioning system; PMV, Predicted Mean Vote; RAS, radiant air conditioning system

Dr. Inagaki said, “The merit of the radiant air conditioning system is it delivered equal temperature in the whole room, providing a comfortable summer environment—not warming, not cooling—to patients and workers.”

Remek Kocz, MD, clinical instructor of anesthesiology at the State University of New York, in Buffalo, expressed interest in seeing these data applied to a pediatric population. “The temperature changes in children are far more noticeable for us in the OR, in both shorter-term and longer-term durations, than in adults,” he said. “This system could have a very significant application in a pediatric population. We have many cases which last under an hour and we notice a significant decline in temperature.”

Dr. Inagaki hopes to conduct a further study that randomly assigns patients to the two air conditioning systems, in an effort to track their accuracy at maintaining temperature and patient comfort.

— Ethan Covey


Drs. Inagaki and Kocz reported no relevant financial disclosures.

 

Source: Anesthesiology News

 

 

Radiant Beats Convection Air Conditioning Systems for Operating Room Comfort

 
 
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The Operating Theatre Journal, OTJ, is published monthly and distributed to every hospital operating theatre department in the UK. The distribution includes both the National Health Service and the Private Sector.

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