Good Recovery after Nontransthoracic Cardiopulmonary Bypass in Rats
Background. Cardiopulmonary bypass (CPB) has been shown to be associated with systemic inflammatory response leading to postoperative organ dysfunction. Unwanted side effects of CPB are well known but poorly understood due to the absence of a stable recovery animal model that is easy to handle and reduces experiment cost and time. The purpose of this study was to establish a good recoverable rat model of CPB to study the pathophysiology of these potential complications.
Materials and Methods. Twenty adult male Sprague-Dawley rats weighing 480 ± 20 g were randomly divided into either the CPB group (n = 10) or the sham group (n = 10). All rats were anesthetized, intubated, and ventilated. The carotid artery and jugular vein were cannulated. The blood was drained from the right atrium via the right jugular and further transferred by a miniaturized roller pump to a hollow fiber oxygenator and back to the rat via the left carotid artery. Priming consisted of 8 mL of homologous blood and 6 mL of colloid. The surface of the hollow fiber oxgenator was 0.075 m2. Rats were catheterized and brought on bypass for 120 minutes at a flow rate of 100-120 mL/kg per minute. Oxygen flow/perfusion flow was 0.8 to 1.0, and the mean arterial pressure remained 60 to 80 mmHg. Blood gas analysis, lactate dehydrogenase, and survival rate were examined subsequently.
Results. All CPB rats recovered from the operative process without incident and recovery remained uneventful in follow-up at 1 week. Normal cardiac function after successful weaning was confirmed by electrocardiography and blood pressure measurements. Mean arterial pressure remained stable. The results of blood gas analysis at different times were within normal range. No significant hemolysis could be detected with the use of lactate dehydrogenase during bypass.
Conclusions. The rat model of CPB can in principle simulate the clinical setting of human CPB. The non-transthoracic model is easy to establish and is associated with excellent recovery. This reproducible model may open the field for various studies on the pathophysiological process of CPB and systemic ischemia-reperfusion injury in vivo.
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