Validation of a Rat Model of Cardiopulmonary Bypass With a New Miniaturized Hollow Fiber Oxygenator

Abstract

Cardiopulmonary bypass (CPB) is an essential component of cardiac surgery, with still unknown device/patient interactions. To evaluate the response of CPB to hemodynamic, biochemical, inflammatory, as well as thermo-pharmacodynamic interactions, a novel miniaturized oxygenator with controlled and standardized specifications has been developed together with an improved surgical central cannulation technique. A hollow-fiber small priming volume (6.3 ml) oxygenator was manufactured according to specifications resulting from engineering, heart surgery and perfusion expertise (Dideco-Sorin Group, Italy) with the following characteristics: Gas Exchange Surface--450 cm2, and Heat Exchange Surface--16 cm2. The oxygenator was tested in vitro and in vivo in five anesthetized, ventilated, open-chest rats using a miniaturized roller pump. Pressures were monitored in the animal before and after the oxygenator. Central venous cannulation through the superior vena cava and aortic cannulation through the carotid artery were used. In vitro: blood oxygenation increased 10-fold (from room air to 100% O2) and PCO2 removal was 2.5-fold. In vivo: CPB was performed without blood prime for 90 minutes (no ventilation) maintaining stable hemodynamics. A maximal blood flow rate of 124 ml/min/kg was obtained. Arterio-venous PO2 gradients were 10-fold (O2 100%) with only small variations when changing blood flow rates. This new, standardized and miniaturized hollow fiber oxygenator, new cannulation technique and CPB circuit achieved optimal gas transfer with small asanguinous priming volumes. This study opens new potentials for various CPB-related study protocols in the small animal.

Role of calcium desensitization in the treatment of myocardial dysfunction after deep hypothermic circulatory arrest

“…This study was conducted in a previously described and validated rat model of CPB [12]. DHCA and CPB-assisted rewarming reproduces the clinical setting of both cardiac surgery interventions and extracorporeal resuscitation after accidental hypothermia.…”

“…Central cannulation was performed as previously described [12]. In brief, after complete sternotomy, a venous cannula (a modified four-hole 16 gauge Angiocath catheter, Delta Med, New York City, NY, USA) was advanced into the right atrium using a right trans-superior vena cava approach, allowing excellent drainage.…”

“…CPB was set up as previously described [12]. The setup consisted of a venous reservoir, a roller pump, a hollow-fiber oxygenator (Sorin, Mirandola, Italy), and a vacuum regulator with an applied pressure of 30 mmH 2 O to facilitate venous drainage, all connected by 1.6 mm internal diameter plastic tubing.…”

“…For energy status determination, the sample preparation and high-performance liquid chromatography (HPLC) measurement of ATP, ADP, AMP and phosphocreatine, as well as hypoxanthine and xanthine, were performed as previously described [12]. A piece of frozen tissue (50 to 100 mg) was homogenized with a micro-dismembranator and deproteinized with 400 μL of 0.4 mol/L perchloric acid.…”

Extracorporeal rewarming from experimental hypothermia: Effects of hydroxyethyl starch versus saline priming on fluid balance and blood flow distribution

“…The extracorporeal circuit (Figure ) was made up of a venous reservoir, a peristaltic pump (Masterflex ® L/S ® ; Cole‐Parmer Instrument Company, Vernon Hills, IL, USA), a hollow‐fibre miniaturized oxygenator (Sorin, Mirandola, Italy) with oxygenation capacities previously validated (Cresce et al., ) and a heat exchanger. All components were connected by silicone tubing with an internal diameter of 3 mm on the venous side (pre‐oxygenator) and 2 mm on the arterial side (post‐oxygenator) of the circuit.…”