动物模型,体外循环 z-bo 2020-08-06 557

　　1 closed chest method (Without thoracotomy)

　　(1) Reproduction method Rats were anesthetized by intraperitoneal injection of sodium pentobarbital at a dose of 30 mg/kg body weight, and then intubated orally, and mechanically ventilated (frequency 60 times/min, peak airway pressure 9.0cmH2O (0.88kPa) ), the left femoral artery was cannulated, and the arterial pressure and arterial blood gas were monitored after heparinization (500U/kg body weight); a 20G trocar was inserted into the tail artery (can also be inserted into the carotid artery or femoral artery) as the CPB perfusion end; A 14-16G trocar engraved with several side holes is inserted through the right jugular vein to the junction of the inferior vena cava of the right atrium as a venous drainage tube, with the help of gravity and siphon to drain blood from the inferior, superior and coronary sinus veins into the rat Blood reservoir 30-40cm below the plane of the heart. The CPB loop is composed of blood reservoir, thermostat, constant flow peristaltic pump, rat micro-membrane oxygenator and connecting pipeline. There is a bypass channel between the blood reservoir and the oxygenator, which facilitates the expulsion of air before the CPB. CPB is pre-filled without blood, and the pre-filling solution is composed of 12 ml of lactated Ringer's solution, 7 ml of 6% hydroxyethyl starch and 1 ml of mannitol. After the circulation starts, the venous blood is introduced into the blood reservoir through the venous drainage tube, and the temperature is changed by the thermostat. After oxygenation, the oxygenator is infused into the artery through the blood pump. The perfusion flow rate at the beginning of the bypass is about 35ml/(kg·min), gradually Increase to 90～100ml/(kg·min). After the bypass starts, the ventilator is stopped to assist breathing, the oxygenator supplies oxygen (FiO2100%), the ratio of oxygen flow to perfusion flow is maintained at 0.8-1.0, and parallel extracorporeal circulation is established. The arterial pressure was maintained at 55-60mmHg (7.32-7.98kPa) during the bypass. After the diverter starts, the temperature-variable water tank should be used to keep warm. After the diverter is stable, the rectal temperature will gradually drop to about 32.0℃, and the temperature will gradually be restored after 45-60 minutes of diverter. CPB will be stopped after the rectal temperature reaches about 37.0℃. Resume mechanical ventilation and evacuate the ventilator after the spontaneous breathing is stable.

　　(2) Model characteristics There are many studies on cardiopulmonary bypass animal model methods. In the past, large animals such as dogs, pigs, and sheep were often used, which was costly and difficult to manage. At present, many scholars have made certain progress by referring to their methods and using rats as experimental subjects, but the methods are diverse and each has its own characteristics. For example, the arterial perfusion can choose the tail artery, femoral artery or carotid artery. The closed-chest method has less damage to the animal, which is good for long-term survival after surgery. The use of tracheal intubation instead of tracheotomy is also to reduce post-operative complications.

　　(3) Comparative medicine Cardiopulmonary brain injury during cardiopulmonary bypass is mainly caused by systemic inflammation and ischemia-reperfusion injury caused by blood contacting non-physiological tubes during cardiopulmonary bypass. Relieving ischemia-reperfusion injury and inflammatory response is the main means of implementing protection during surgery. To study the body's pathophysiological response within a certain period of operation after surgery, long-term survival of the animal must be the main condition, so the closed chest method can be used.

　　2 By methods of thoracotomy

　　(1) Reproduction method Inject heparin saline into the femoral vein at the amount of 1000μg/kg body weight, cut the neck and chest skin, free the organs, and then intubate the respirator. Open the chest, free the right common carotid artery and superior vena cava, place double ligatures, insert 22-gauge and 20-gauge puncture needles to tap the arteriovenous extracorporeal circulation tube (the superior vena cava puncture needle enters the right atrium, the arterial tube first Pre-filled with gel), fixed with a ligature, and ligated the distal end of the blood vessel. The temperature of the pipeline is maintained at 38°C through a thermostatic circulator. Free the aorta and pulmonary artery, and set the 10th line for blocking. Take the donor mouse, anesthetize the heparinized, and connect the tracheal tube to a ventilator (the method is the same as above). After opening the chest, cut the right common carotid artery for bleeding and add a small amount of colloid as a prefilling solution. The heart and lungs are completely removed, and the heart apex is cut off. Intubate the human pulmonary artery through the right ventricular outflow tract, fix it with No. 10 wire (cut off part of the left ventricular wall, and ligate around the right ventricular wall and the ventricular septum to facilitate tightening), cut the left atrial appendage to facilitate pulmonary venous return, and insert the tube into the body The circulatory venous pipeline is fixed with the experimental frame, and a blood reservoir connected with a thermostatic circulator is placed underneath. The pulmonary venous blood is recovered by a bypass pump and pumped into the right common carotid artery of the experimental mouse through the arterial pipeline. The circulation route at this time is: experimental mouse right atrium → venipuncture needle, tube and bypass pump → isolated pulmonary artery → isolated pulmonary circulation → isolated pulmonary vein and left atrial appendage → constant temperature blood storage → bypass pump and pipeline → arterial puncture needle →Right common carotid artery of experimental mouse→Circulation of experimental mouse.

　　(2) The characteristics of the model The open-chest method is closer to the clinical situation, but the animals are difficult to survive after surgery, so it is generally not used to study the postoperative body response. This method introduces the establishment of an extracorporeal circulation model by using isolated rat lungs as an oxygenator for extracorporeal circulation, which overcomes the difficulty of making mechanical oxygenators for small animals. But its oxygenator can also use mechanical oxygenator.

　　(3) The more medically ideal rat cardiopulmonary bypass model should be an experimental device that is as close to modern clinically as possible. It needs to have the following capabilities: full-flow circulation support at room temperature or low temperature (>150～180ml/( kg·min)); continuous bypass for 1 to 2 hours, and maintain moderate blood dilution and destroy fewer blood cells; the precharge does not exceed the autologous blood volume of adult rats; it can carry out sufficient and effective heat exchange to achieve central cooling Rewarming; experimental animals can obtain stable long-term survival. This needs further research. In actual work, different rat models can be used according to research purposes.