Background Large animal cardiopulmonary bypass (CPB) models are expensive,and prevent assessment of neurocognitive function,and difficulties with long-term recovery.The purpose of this study was to establish a novel rat model of cardiopulmonary bypass for deep hypothermic circulatory arrest without blood priming.Methods Twenty adult male Sprague-Dawley rats weighing 450-560 g were randomized to CPB with deep hypothermic circulatory arrest (DHCA) and control groups,with 10 rats each.The experimental protocols,including blood and crystalloid fluid administration,anesthesia,orotracheal intubation,ventilation,cannulation,and heparinization were identical in both groups.After inducing cardiac arrest,the circuit was turned off and rats were left in a DHCA state for 15 minutes.Rats were rewarmed to 34℃ to 35℃ over a period of 36 to 42 minutes using CPB-assisted rewarming,a heating blanket,and a heating lamp along with administration of 0.1 mEq of sodium bicarbonate and 0.14 mEq of calcium chloride.The remaining priming volume was reinfused and animals were weaned from CPB.Results All CPB with DHCA processes were successfully achieved.Blood gas analysis and hemodynamic parameters were in the normal range.The vital signs of all rats were stable.Conclusions Our CPB circuit has several novel features,including a small priming volume,active cooling/rewarming processes,vacuum-assisted venous drainage,peripheral cannulation without thoracotomy or stemotomy,and an accurate means of monitoring peripheral tissue oxygenation.