Anesthesia for Cardiac Surgery - Other Cardiac Procedures
Off-bypass CABG is performed to avoid the complications associated with CPB and to minimize aortic manipulation. Proximal grafts are performed using either a partial aortic cross-clamp technique or a specifically designed proximal anastamotic device that precludes aortic clamping. Distal grafts are performed using one of several heart stabilizing devices. Considerations for this procedure include the following:
- Consider tailoring anesthetic management to allow possible early extubation after surgery (e.g., fentanyl 5 to 10 μg/kg, volatile anesthetic followed by an infusion of propofol or dexmedetomidine).
- Heparin 350 units/kg IV is given, and the ACT is maintained above 400 seconds. This allows the patient to be emergently initiated on CPB if necessary. Antifibrinolytic therapy is avoided. A small dose of protamine (50 to 100 mg) is given after the procedure.
- ECG monitoring can be difficult because the heart is placed in nonanatomic positions. Nonetheless, it is important to establish a baseline ECG (for each position) and to monitor the ST segments.
- Hemodynamic instability is common, particularly when the surgeon is performing the distal anastomoses. Grafts to vessels with less disease tend to be associated with more instability than those to vessels that are occluded. Increasing MAP to optimize coronary perfusion is critical for the ischemic heart during creation of the distal anastomosis. If hemodynamically intolerable ischemia results, coronary shunting may be indicated. Occasionally, repositioning of the heart is required to permit augmented right-sided filling when hemodynamic instability is due to obstruction of right heart inflow.
- Volume requirements tend to be high. A full heart tends to tolerate physical manipulation better.
- Ventricular dysrhythmias may be treated with amiodarone 150 mg IV bolus and then followed with 1 mg/min infusion. Acid–base and electrolyte abnormalities should be corrected.
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