establishment of extracorporeal circulation

The establishment of extracorporeal circulation surgery is part of human surgery. The use of medicine is high. It requires the combination of in vivo surgery and in vitro surgery to achieve a smooth operation. Treatment of diseases: heart disease, acute pulmonary heart disease Indication heart disease. Contraindications Malnutrition, anemia, and liver, kidney, and other organ dysfunction. Preoperative preparation 1. Eliminate all infected lesions. 2. Correct malnutrition, anemia, and liver, kidney, and other organ dysfunction. 3. Correct heart failure or put the patient in the best possible condition. 4. Stop the digitalis and diuretics 48 hours before surgery. 5. Use an ordinary diet 1 week before surgery to adjust the electrolyte balance. If the patient takes long-term diuretics, the oral potassium chloride should be increased in the first week before surgery to overcome the deficiency of potassium in the body. 6. Start antibiotics with antibiotics on the 3rd day before surgery. Give a dose of antibiotics when you use the medicine before surgery. 7. In severe cases, glucose, insulin and potassium chloride solution (gik) were intravenously administered 1 week before surgery to protect the myocardium. 8. Psychotherapy should be performed on patients before surgery to eliminate concerns and enhance cooperation between doctors and patients. Let the patient understand the various situations that may occur during the operation to facilitate the patient's active cooperation. Surgical procedure 1. Incision: The sternal median incision is a standard extracorporeal circulation open heart surgery incision, which is well exposed and suitable for cardiac surgery in any part. The incision was slightly from the sternal notch and reached about 5 cm below the xiphoid. 2. Saw the sternum: Cut the sternal periosteum with an electric knife along the center, and separate the sternal incision to the sternum; then dissect the xiphoid and separate the posterior sternal space. After the xiphoid is removed, the sternum is sawn along the midline with a wind (electric) saw. The periosteum is electrocoagulated to stop bleeding, and the sternum is stopped by bone wax. 3. Cut the happy bag: cut the happy bag in the middle of the line, get the ascending aorta reflexed part, release the diaphragm, and cut the lower part of the incision to the side to facilitate the exposure. After that, the pericardial margin is sutured to the soft tissue outside the sternum, and the sternum is opened with a spreader to reveal the heart. 4. Extracardiac exploration: Exploring the size, tension, and tremor of the aorta, pulmonary artery, left and right atrium, left and right ventricles, superior and inferior vena cava, and pulmonary veins. Also check for the presence of left superior vena cava and other abnormalities that can be found outside the heart. 5. Establish extracorporeal circulation: (1) Vena cava strap: first separate the gap between the aorta and the pulmonary artery, lift the aortic band, pull the band on the ascending aorta to the left, reveal the inside of the superior vena cava, and use the right angle pliers to wrap around the inside of the superior vena cava. After the strap. In the same way, the lower vena cava was placed around the inferior vena cava with a lower lumen. (2) Arterial intubation: At the distal end of the ascending aorta, the concentric purse is sutured with the 7th line, and the blood vessels are not penetrated, and are sutured in the adventitia of the aorta, and the opening of the purse line is one by one. Put the purse string into the hemostatic device to stop bleeding and fix when intubating. The outer membrane of the central portion of the purse is removed. After injecting heparin into the right atrial appendage (3mg/kg), use a small round (tip) blade to cut a small incision in the center of the purse, which is slightly smaller than the diameter of the arterial cannula. When the blade is withdrawn, the artery cannula is sent into the ascending aortic incision. Tighten the hemostats of the two purse lines and secure the arterial cannula to the hemostat with a thick wire. Finally, the arterial cannula is fixed on the edge of the incision or the petiole of the distractor, and the cannula is connected to the artificial heart-lung machine. (3) Cavernous vein cannulation: a purse string is sutured in the right atrial appendage and the right atrium, and a hemostatic device is placed, and then the incision is inserted into the superior and inferior vena cava cannula (generally inserted through the atrial appendage) to tighten the hemostat. A 2 to 3 mm atrial appendage and atrial wall below the incision were ligated around the cannula with a thick wire, and the upper and lower lumen cannula was fixed by the ligature to prevent slipping. Connect the upper and lower lumen cannula to the artificial heart-lung machine. (4) Cold heart cardioplegic perfusion cannula: a suture was placed on the anterior lateral membrane of the ascending aorta and placed in a hemostat. The cold heart cardioplegia is filled with the needle and the gas is inserted into the central part of the sacral suture into the ascending aorta. The hemostasis is tightened, and the cannula and the hemostat are fixed together by thick lines. Connect the cannula to the infusion device. (5) Left heart drainage cannula: You can choose one of the following: Left atrial drainage: a large suture suture at the junction of the right upper pulmonary vein root and the left atrium, with a hemostat. After cutting a small opening in the fistula suture, insert the left atrial drainage tube into the left atrium and tighten. The hemostat is ligated with a thick wire and the drainage tube is fixed to the hemostat. Connect the drainage tube to the artificial heart-lung machine. Left ventricular drainage: some patients have better left ventricular drainage, a suture in the left ventricle near apical avascular region, a hemostat, a small incision in the center of the sacral suture, and a small incision The left ventricular drainage tube tightens the hemostat and fixes the drainage tube together with the hemostat. Connect the drainage tube to the artificial heart-lung machine system. Check all the pipes and their connections without error. It is sure that there is no obstacle in each channel, and the extracorporeal circulation can be started. After several minutes of parallel circulation, the upper and lower vena cava are blocked and enter the complete extracorporeal circulation. At this time, the upper and lower vena cava blood It is completely intubated into the artificial heart-lung machine and does not flow into the right atrium. At the same time, the blood is cooled. (6) Blocking the ascending aorta: When the whole body temperature drops to about 30 °C, lift the ascending aorta and use the aortic occlusion forceps to block the ascending aorta. Immediately, 4°C cold heart cardioplegia (1015ml/kg) was injected from the perfusion tube of the aortic root, and the surface of the heart was cooled with 4°C iced saline or ice particles to make the heart stop quickly. The operational indicators of cardiopulmonary bypass are as follows: Mean arterial pressure: 5.33 ~ 9.33 kPa (60 ~ 90 mmhg). Central venous pressure: 0.59 ~ 1.18kpa (6 ~ 12cmh2o). Body temperature: general surgery about 28 ° C; complex heart surgery can be used at a low temperature of 20 ° C ~ 25 ° C. Myocardial temperature: maintained at 15 ° C ~ 20 ° C. Flow rate: 50 ~ 60ml / kg for medium flow; 70 ~ 80ml / kg for high flow, clinically used high flow. Children and infants should have a higher flow rate than adults. Dilution: The cell volume is generally between 25% and 30%. Blood gas analysis: pao213.3 ~ 26.6kpa (100 ~ 200mmhg). Pvo2: 3.3 to 5.3 kPa (25 to 40 mmhg). Ph: 7.35 to 7.45. Paco2: 4.6 ~ 6.0kpa (35 ~ 45mmhg). Urine volume: 2 ~ 10ml / kg / hour. Blood potassium: During the extracorporeal circulation, k+ is maintained at 4-6 mmol/l, and potassium chloride should be given 1 to 2 mmol/kg per hour. Heparinization: human body according to 3mg/kg; pre-filled liquid 1mg/100ml; after 1 hour of operation, heparin was supplemented by artificial heart-lung machine. The act should be kept at around 600 seconds during operation. 6. Terminate extracorporeal circulation: (1) Rewarming: After the main operation in the heart is completed, rewarming can be started, but the heart still needs low temperature protection. (2) Exhaust: After the heart incision is sutured, the apical pin can be vented, the aortic root can be vented, or the perfusion needle can be removed and vented through the pinhole on the aortic wall. Remove the ice or ice brine from the pericardium before venting. (3) Open aorta: Open the ascending aorta blocking forceps. At this time, the left heart should be circulated smoothly to prevent the left heart from expanding. (4) Defibrillation: After opening the ascending aorta blocking forceps, if the conditions are right, the heart can automatically re-jump. If there is no re-jump, the electric shock can be used to debounce. Generally, the direct current is 5 to 50 watts. Blood gas and ions should be checked before defibrillation. If it is not normal, it should be corrected immediately to ensure successful recovery under physiological conditions. After the double jump, the heart should be kept at no load for a period of time to facilitate the recovery of myocardial function. (5) Auxiliary circulation: open the upper and lower cavity blocking bands after resuscitation, so that the complete extracorporeal circulation becomes a parallel cycle to assist the heart beat and reduce the burden on the heart. The longer the intracardiac operation time, the longer the time required for the assisted circulation to facilitate the recovery of cardiac metabolism and function. (6) Stop cardiopulmonary bypass: The conditions for cardiopulmonary bypass are: 1 body temperature up to 36 ° C; 2 mean arterial pressure 8 ~ 10.66 kPa (60 ~ 80 mmhg); 3 no significant bleeding in the surgical field; 4 blood gas analysis report normal; 5 blood ion normal; 6 no serious heart rhythm disorder. Before the shutdown, vasodilators and diuretics, such as sodium nitroprusside, furosemide, etc., can be used to gradually reduce the blood in the artificial heart-lung machine and achieve a positive balance to the human body. By the time of the shutdown, only the minimum amount of blood necessary to maintain operation is left in the machine. After the shutdown, continue to use the arterial pump to slowly transfuse blood to prevent blood shortage, and also prevent the input speed from being too fast, causing the heart to swell and damage the myocardial function. (7) Neutralization of heparin: The amount of protamine is calculated based on the measured value of act; or heparin is neutralized by protamine in an amount of 1:1. Prevent excessive or insufficient use of protamine. (8) Supplemental potassium: Before terminating extracorporeal circulation, the general patient has natural diuretic. If the urinary flow rate is not ideal enough, furosemide can be used. At this time, the rhythm disorder caused by hypokalemia is most likely to occur. The amount of potassium should be monitored according to the amount of urine and serum potassium: generally 0.7 to 1.0 g of potassium chloride should be input for every 500 ml of urine. To prevent excessive liquid load, intravenous infusion of 6:1000 to 15:1000 potassium chloride solution is required. Note that high-concentration potassium should be intubated from the large vein, and high-concentration potassium in the peripheral vein is difficult to ensure smoothness. (9) Supplementary blood volume: After the machine is stopped, the wound is still losing blood, and diuresis (urinary flow is often faster), so fresh blood and plasma should be input immediately to supplement the lack of blood volume. The ratio of blood to plasma can be determined based on cell pressure and hemoglobin measurements. (10) Extubation: After the shutdown, under the condition of stable condition, the upper lumen cannula can be removed and the inferior cannula can be retracted into the right atrium. If the condition continues to be stable, the inferior cannula can be removed. If you do not need to enter the blood inside the machine, the arterial cannula should be removed as early as possible. At the same time, protamine was injected into the ligature line at the aortic cannula, and the injection of protamine into the aorta rarely caused a decrease in blood pressure. complication Heart failure, anemia.

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