动物造模,药效评价,体外循环 z-bio 2024-08-26 481

　　1. Closed chest technique

　　(1) The replication method involves intraperitoneal injection of pentobarbital sodium at a dose of 30mg/kg body weight in rats, followed by oral intubation and mechanical ventilation (frequency 60 times/min, peak airway pressure 9.0cmH2O (0.88kPa)). Left femoral artery catheterization is performed, and arterial pressure and arterial blood gas are monitored after heparinization (500U/kg body weight); A 20G trocar is inserted into the tail artery (or carotid or femoral artery) as the perfusion end for CPB; A 14-16G trocar with several side holes engraved on the front end is inserted through the right jugular vein into the junction of the right atrium and inferior vena cava as a venous drainage tube. The inferior vena cava, superior vena cava, and coronary sinus vein are drained by gravity and siphon action into a blood reservoir located 30-40 cm below the level of the rat heart. The CPB circuit consists of a blood reservoir, a temperature regulator, a constant flow peristaltic pump, a rat miniature membrane oxygenator, and connecting pipes. There is a bypass channel between the blood reservoir and the oxygenator, which facilitates the discharge of air before CPB. CPB adopts bloodless pre filling, and the pre filling solution consists of 12ml of lactate Ringer's solution, 7ml of 6% hydroxyethyl starch, and 1ml of mannitol. After the start of circulation, venous blood is introduced into the blood reservoir through a venous drainage tube, heated by a temperature regulator, and oxygenated by an oxygenator before being injected into the artery through a blood pump. At the beginning of circulation, the perfusion flow rate is about 35ml/(kg · min), gradually increasing to 90-100ml/(kg · min). After the start of bypass, stop the ventilator assisted breathing and provide oxygen (FiO2100%) through the oxygenator. Maintain the ratio of oxygen flow to perfusion flow at 0.8-1.0, and establish parallel extracorporeal circulation. During the bypass process, the arterial pressure is maintained at 55-60mmHg (7.32-7.98kPa). After the start of the diversion, pay attention to insulation by using a variable temperature water tank. After the diversion is stable, gradually reduce the anal temperature to about 32.0 ℃. After 45-60 minutes of diversion, gradually rewarm it. Stop CPB when the anal temperature reaches about 37.0 ℃. Resume mechanical ventilation and evacuate the ventilator after stable spontaneous breathing.

　　(2) There have been many studies on extracorporeal circulation animal models, but in the past, large animals such as dogs, pigs, and sheep were often used, which were costly and difficult to manage. At present, many scholars have made certain progress by referring to its method of using rats as experimental subjects, but the methods are diverse and each has its own characteristics. For example, arterial perfusion can be selected from the tail artery, femoral artery, or carotid artery. The closed chest method causes less damage to animals and is beneficial for long-term survival after surgery. The use of endotracheal intubation instead of tracheotomy is also to reduce the occurrence of postoperative complications.

　　(3) The cardiorespiratory brain injury in comparative medicine during extracorporeal circulation is mainly caused by systemic inflammatory response and ischemia-reperfusion injury caused by blood contact with non physiological pipelines during extracorporeal circulation. Reducing ischemia-reperfusion injury and inflammatory response is the main means of intraoperative protection. To study the pathological and physiological reactions of the body during a certain period after surgery, the main condition must be the long-term survival of the animal, so the closed chest method can be used.

　　2 open chest techniques

　　(1) The replication method involves injecting heparin saline solution into the femoral vein at a dose of 1000 μ g/kg body weight, cutting open the skin of the neck and chest, freeing the organs, and inserting a tube to connect to a ventilator. Open the chest, free the right common carotid artery and superior vena cava, place double channel ligatures, and insert 22 and 20 puncture needles respectively to connect the arteriovenous extracorporeal circulation tubes (the superior vena cava puncture needle enters the right atrium, and the arterial tube is first pre filled with colloid), fix the ligatures, and ligate the distal end of the blood vessel. The pipeline is maintained at a temperature of 38 ℃ through a constant temperature cycler. Separate the aorta and pulmonary artery, and place Line 10 for blocking. Take the donor mouse, anesthetize it with heparin, insert a tracheal tube and connect it to a ventilator (the same method as above). After thoracotomy, cut off the right common carotid artery and add a small amount of colloid as a pre filling solution. Remove the heart and lungs intact, cut off the apex of the heart, insert the human pulmonary artery through the right ventricular outflow tract, fix it with line 10 (cut off part of the left ventricular wall, ligate the line around the right ventricular wall and interventricular septum to facilitate tightening), cut open the left atrial appendage to facilitate pulmonary vein reflux, insert the tube into the extracorporeal circulation venous tube, fix it to the experimental frame, and place a blood storage device connected to the constant temperature circulation device below. Collect pulmonary vein blood and pump it into the right common carotid artery of the experimental mouse through the arterial tube with a bypass pump. At this time, the circulation route is: right atrium of the experimental mouse → venipuncture needle, catheter, and bypass pump → isolated pulmonary artery → isolated pulmonary circulation → isolated pulmonary vein and left atrial appendage → constant temperature blood reservoir → bypass pump and catheter → arterial puncture needle → right common carotid artery of the experimental mouse → systemic circulation of the experimental mouse.

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

　　(3) The ideal rat extracorporeal circulation model in medicine should be an experimental device that is as close to modern clinical practice as possible. It needs to have the following abilities: full flow circulatory support at room temperature or low temperature (>150-180ml/(kg · min)); Continuous flow for 1-2 hours, while maintaining moderate blood dilution and minimal destruction of blood cells; The pre charge amount shall not exceed the autologous blood volume of adult rats; Capable of conducting sufficient and effective heat exchange to achieve central cooling and reheating; Experimental animals can achieve stable long-term survival. This requires further research. In practical work, different rat models can be used according to the research objectives.