Transcript Document
Anaesthesia for cardiovascular surgery with extracorporeal circulation Key points • Understanding of the pathophysiology of the heart diseases • Undestanding of pharmacology • Cardiopulmonary bypass • TEE • Myocardial preservation Cardiopulmonary bypass (CPB) • Collection of venous blood (reservoir) • Adds oxygen (oxygenator) • Returns blood to a large artery (heat exchanger) • Level of fluid in reservoir is critical (type of pumps) • Activation of stress hormones Systemic hypothermia • Core body temperature (20-30 oC) • Metabolic oxygen requirements halved with each of 10 oC) • Rewarming via CPB • Profound hypothermia (15-18 oC ) • Total circulatory arrest • Adverse effects of hypothermia: platelet dysfunction, reversibly coagulopathy Myocardial preservation • What is a damage to the myocardium? • Imbalance between oxygen supply and demand • Ischemia, Stunning, Hibernation, Infarction • Aortic cross clamping • Ventricular fibrillation and distension • Coronary vessels emboli Potassium and blood cardioplegia • • • • Kalium 10 – 40 mEq/L Sodium < 140 mEq/L Calcium, Magnesium Others compounds like: glucose, buffers, lidocaine, glucocoticoids • Antegrade and retrograde (via sinus venosus) route of administartion Vasodilators • ACE Inhibitors: captopril, enalapril • Nitrovasodilatators: NTG, NPS, molsidomina, hydralazyna • Calcium channel blockers • Potassium channel activators: diazoxide, minoxidil, pinacidil, cromakalin Nitrate sides of action Anticoagulation • ACT 400-450 sec • Heparin 300-400 U/kg (3 mg/kg) by central line • Resistance to heparin (antithrombin III deficiency): reversed by 2 U FFP, antithrombin III concentrate • Heparin induced thrombocytopenia (alternatives: hirudin, bivalirudin, ancrod) Bleeding prophylaxis • Aprotinin (4-6 mln KIU) • Tranexamic acid (10 mg/kg) followed by 1mg/kg/h • Epsilon-aminocapronic acid 5-10 g followed by 1 g/h Bypass period • Monitoring • Flow and pressure MAP = Pump flow x SVR • Hypothermia, cardioplegia, • Ventilation • pH stat management (need CO2) • Alpha-stat management Important points • • • • Anesthesia Cerebral protection Termination of and weaning from CPB Reversal of anticoagulation (Protamine 1-1,3 mg protamine per 100 U of heparin) • Persistent bleeding • Transportation • Postoperative period