Evaluation of a Rat Cardiopulmonary Bypass Model Using an Extraluminal Flow Oxygenator.

BACKGROUND

Cardiac operations with cardiopulmonary bypass (CPB) trigger a systemic inflammatory response. To understand the underlying mechanisms behind the biological reactions during CPB, rat models that mimic clinical CPB have been developed. Previously, a rat CPB model incorporating an intraluminal flow oxygenator was employed to accommodate the limited blood volume of rats. This study aimed to evaluate a rat CPB model incorporating an extraluminal flow oxygenator.

METHODS

The effective membrane area and priming volume of the extraluminal flow oxygenator were 0.0236 m2 and 3.0 mL, respectively. Rats were divided into three groups: (i) SHAM group (surgical preparation only); (ii) CPB with intraluminal flow oxygenator group (CPB Int-oxy); and (iii) CPB with extraluminal flow oxygenator group (CPB Ext-oxy). Blood samples were collected before and at 60 and 120 min after CPB initiation. Hemodynamics, blood gases, blood cell counts (RBC, WBC, PLT), and inflammatory responses (IL-6, IL-10, TNF-α) were measured.

RESULTS

Each CPB group maintained an arterial pressure and Hb at approximately 75 mmHg and 9.5%, respectively, without blood transfusion, and an oxygenation and carbon dioxide removal from the blood were confirmed. In the CPB Ext-oxy group, PLT counts were significantly preserved at 60 and 120 min after the start of circulation compared with those in the CPB Int-oxy group. However, no significant differences in IL-6, IL-10, or TNF-α levels were observed between the CPB groups.

CONCLUSIONS

Incorporating the extraluminal flow oxygenator into a rat CPB model enables the simulation of CPB conditions that closely mimic those encountered in clinical CPB.