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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).
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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
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