Portable, Closed-Loop Heater-Cooler Unit for Temperature Management in Mechanical Circulatory Support

Temperature management is critical in patients on mechanical circulatory support. Heater-cooler units (HCUs) deliver temperature-controlled solution to modulate patients’ temperature, yet they have several limitations. Extant systems have limited temperature-titration capabilities, bulky size, poor portability, extensive disinfection protocols, and depend on AC power. We developed a portable, battery-powered HCU with a closed-loop autoregulation that autonomously maintains the targeted blood temperature. Performance was assessed in a mock circulatory loop and validated in a porcine ex vivo heart perfusion (EVHP) and cardiopulmonary bypass (CBP) model. The HCU reliably maintained normothermia in both in vitro and porcine studies. Time to target temperature from deep hypothermia (18°C) scaled with perfusate flow and volume in vitro: 26.0 minutes for EVHP, 39.0 minutes for pediatric CBP, and 104.1 minutes for adult CBP. For EVHP cases, blood temperature rose from an initial 15.41°C and 25.17°C following cardioplegic arrest to target in 24.37 and 26.48 minutes, maintaining normothermia for approximately 6 and 15 hours, respectively. The HCU also maintained normothermia for a 41 kg pig during 159 minutes of CBP. Isolated battery power maintained normothermia for 2 hours in EVHP conditions. The HCU successfully modulated heating and cooling to achieve and maintain the target temperature without perfusionist intervention following target selection.