A novel augmented venous-drainage model of cardiopulmonary bypass for deep hypothermic circulatory arrest without blood priming

Cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) are commonly used in cardiac surgery. However, the mortality and morbidity are still high in practice. Developing novel protective stategies and elucidating the underlying mechanisms for the pathophysiological consequences of DHCA have been hampered because of the absence of a satisfactory recovery animal model. The aim of this study was to establish a novel and safe DHCA model without blood priming in rats to study the pathophysiology of potential complications.

Ten adult male Sprague-Dawley rats (age, 14-16 weeks; weight, 200-300g) were used. The entire CPB circuit consisted of a modified reservoir, a custom-designed small-volume membrane oxygenator, a roller pump and a home-made heat exchanger, all of which were connected via silicon tubing. The volume of the priming solution was less than 10 ml. The right jugular vein, right carotid artery and left femoral artery were cannulated. The blood was drained from the right atrium through the right jugular vein and fed back to the rat via the left femoral artery. CPB was commenced at a full flow rate. The animals were cooled to a pericranial temperature of 18°C and then subjected to 45 minutes of DHCA with global ischemia. Circulatory arrest was followed by rewarming and over 60 minutes of reperfusion. CPB was terminated carefully. Blood in the circuit was centrifuged and slowly transfused to achieve optimal hematocrit. Blood gas and hemodynamic parameters were recorded at each time point before CPB, during CPB and after CPB.

All CPB and DHCA processes were achieved successfully. No rat died in our research. Blood gas analyses at different times were normal. Cardiac function and blood pressure were stable after the operation. The vital signs of all the rats were stable.

The novel augmented venous-drainage CPB and DHCA model in rats could be established successfully without blood priming.