Improving Decreased Heater-Cooler Efficiency as a Result of Heater-Cooler Infection Control Strategy

Heater-cooler units (HCUs) play a vital role in temperature management during cardiopulmonary bypass. In recent years, HCUs have been shown to play a significant role in the propagation of bacteria causing patient infection and significant harm. As a result, various institutions across the world have begun moving the HCU either far away or outside of the operative theater entirely. The purpose of this study was to examine the effect that the increased length of HCU water lines have on the ability of the device to heat and cool. We hypothesized that the increase in water line distance leads to a decrease in HCU efficiency and that insulating the water lines would blunt the effect of this increase in distance. Five water line conditions were compared under two cooling and two warming ranges. Short water lines, long water lines, and long water lines with foam, rubber, or tape insulation were compared. Cooling from an arterial line temperature of 26.7-19.7°C showed no difference between conditions with the exception that every long line condition takes significantly longer to cool than short water lines. Cooling from 35.6 to 28.6°C revealed that all insulations reduce the cooling time compared with long water lines without insulation, but only foam insulation reduces to the level of the short water lines. During warming conditions, all insulations reduced the warming time compared with long uninsulated water lines, but none were comparable with short water lines. Increased water line length leads to a decrease in HCU efficiency. Insulation is effective at increasing efficiency of long water lines, but only at warmer temperatures and not to the level of short water lines. Only foam-insulated long water lines were able to match the efficiency of short water lines, but only across a single temperature range.