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Off-Pump Coronary Artery Bypass Surgical & Anesthetic Concerns. Brian D-L Marasigan, M.D. CV Anesthesiology UT-Houston. Surgical and Anesthetic Concerns. Define Off-pump CABG Surgery Define basic anesthetic concerns Understand basic cardiac anatomy and physiology
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Off-Pump Coronary Artery Bypass Surgical & Anesthetic Concerns Brian D-L Marasigan, M.D. CV Anesthesiology UT-Houston
Surgical and Anesthetic Concerns • Define Off-pump CABG Surgery • Define basic anesthetic concerns • Understand basic cardiac anatomy and physiology • Understand intra-operative goals • Understand the problems associated with On-Pump verses Off-Pump Surgery
Off pump CABG Surgery • Off-pump = Without the use of assistive devices • Cardiopulmonary Bypass (CPB) Machine • Left Heart Bypass Machine • Ventricular Assist devices • Beating Heart CPB = CPB without use of aortic cross clamp or cardiac arrest. • On-pump CABG = CABG on CPB
CABG Surgery • Heart Port- Endoscopic Heart Surgery • MIDCAB – Thoracotomy approach (usually for single vessel LIMA to LAD bypass) • Robotic Heart Surgery – Davinci robot for minimally invasive heart surgery • PADCAB – Perfusion assisted CAB – immediate perfusion of grafts
Basic Anesthetic Perspective • A Complicated heart surgery without the support of Cardiopulmonary Bypass • The basic cardiac physiology related to all surgical patients • Optimize cardiac function while minimizing cardiac stress
Basic Anesthetic Concerns • Cardiac Function and Metabolism • Coronary Anatomy • Utilization of Oxygen • Supply of Oxygen and Nutrients • Demand of Oxygen and Nutrients
Oxygen Extraction • Coronary Oxygen Extraction- Highest – 65-75% • Kidney and Brain • Whole body 25-35% • Increased extraction SVC vs IVC • VO2- Oxygen Consumption • MVO2- Myocardial Oxygen Consumption • SVO2- Venous Oxygen saturation – Mixed Venous Oxygen • Maximal Extraction ~ Circulation (80ml/min) >Oxygenation (20%vol) 8-16 mlO2/min rest vs 70+ mlO2/min exercise
Supply of Oxygen and Nutrients • CaO2 = 1.31xHgbxSaO2 + 0.003PaO2 • CPP = AoDBP – LVEDP (SVR) • Preload = LVEDV (SV) • HR = Diastolic Filling Time • Coronary Stenosis – R=8Lμ/∏r4
Demand of Oxygen and Nutrients • Wall Stress = RxP/WT (Afterload, LVH) • HR - Increased # Contractions • Inotropy – increased contractility (work force) • LVEDV – Frank-Starling Curve • Arrhythmia – increased MVO2 • Stress – Demand Ischemia
Anesthetic Management • GETA with or without Thoracic Epidural • Monitors – Arterial Line, CVC, PAC, TEE, Cerebral Oximetry, 5Lead EKG, ASA monitors • IVF – Fluid warmers, Colloid vs Crystalloid, RBCs • Drugs – Low dose Heparin, Antifibrinolytics, Narcotics • CPB on Backup
Anesthetic Goals • Maintain NSR with HR 60-80 • Increase Preload to maintain filling, maximize starling curve, and avoid excessive LVEDV/Wall Stress • Maintain high Hgb, SaO2, PaO2 • Maintain AoDBP (Afterload - NE) • Maintain CO (SV,CBF) • Minimize Sympathetic Stimulation (Pain, Ionotropy, Chronotropy) • Provide Coronary Dilation and Ischemic Preconditioning • Provide excellent communication • Prepare for next stages of operation
Basic Surgical Process • Graft Harvesting – LIMA, LSVG, LRad, RIMA • Heparinization • CPB Cannulation • Proximal Anastomosis • Distal Anastomosis (Snaring & shunting) • Reversal of Protamine • Decannulation • Maintenance of normothermia, graft patency, coagulation, GETA
Benefits of OPCAB Surgery • Avoidance of CPB • Coagulopathy • Neurologic Deficit • Air/Plaque Embolism • Aortic Manipulation/Clamping • Avoidance of Ventricular Arrest, Defibrilation, Pacing • Difficulty of separation from CPB • Transfusion PRBC, FFP, PLT, Cryo • Cannulation site trauma/bleeding • Risk of Recall • Risk of full dose Heparin and Protamine • Risk of deep hypothermia <34 • Risk of Hemodilution and Volume Shifts • Potentially Faster Surgery
Benefits of OPCAB Surgery • Decreased Cost to Patient • Decreased ICU and Hospital stay • Decreased duration of Intubation • Decreased requirement for Inotropic, Chronotropic, or Vasoconstrictive support • Potentially decreased risk of infection and improved wound healing • Potentially Faster recovery
Risks of OPCAB Surgery • Direct trauma to myocardium • Unprotected myocardium with occlusion of coronary targets • Decreased cardiac function intra-op • Decreased Cardiac Output / Organ perfusion / Systemic Pressure • Increased requirement for drips intra-op • Decreased graft patency due to technical difficulty or thrombosis • More work for Anesthesiologist
Off-Pump Coronary Artery Bypass Surgical & Anesthetic Concerns