Model of Normothermic Long-term Cardiopulmonary Bypass in Swine Weighing More than Eighty Kilograms

Purpose: Swine models have been used to study cardiovascular disease, cardiac physiology, and transplantation, and have been associated with problems, such as friability of certain organs, anesthesia difficulties, ventricular fibrillation, and edema. We describe a stable model of extended cardiopulmonary bypass (up to 22 h) in swine weighing > 80 kg to be used as a research model.

Methods: Swine (n = 5, 88 ± 6 kg) had both femoral arteries cannulated and after open sternotomy, a two-stage venous catheter was placed in the right atrium/caudal vena cava. The circuit was primed with four parts blood and one part 0.9% NaCl.

Results: Cardiopulmonary bypass was maintained for 10 to 22 h, with the following parameters measured at beginning/middle/end: heart rate, 108 to 134 beats per minute; hematocrit, 30 to 38%; glucose concentration, 4 to 11 mmol/L; lactate concentration 6 to 7 mmol/L; pH 7.4 to 7.5; pCO₂, 35 to 38 mmHg; pO₂, 197-228 mmHg; HCO⁻₃, 21 to 25 mmol/L; base excess, −3 to +2; and total urine output, 425 to 1,600 ml.

Conclusions: Factors responsible for the success of this model include a higher oxygen concentration on initiation of cardiopulmonary bypass (567 ± 54 mmHg), maintenance of appropriate hematocrit, and use of non-citrated blood-crystalloid prime. The results indicate a stable model of normothermic long-term cardiopulmonary bypass in swine that allows researchers a longer opportunity for further exploration of relevant research issues.