CABG anesthesia, step by step

An on-pump coronary bypass is not one anesthetic but three transitions with an interval between them — onto bypass, the arrested heart, and separation — each with its own checklist. Underneath all of them sits the defining tension: a myocardium whose oxygen supply is already compromised has to survive induction and the pre-bypass period without the ischemia the operation exists to fix.

1. Before induction

Multivessel coronary disease rarely travels alone. Diabetes, carotid and peripheral vascular disease, renal impairment and reduced ventricular function are the usual company, and each changes something. Preoperative antiplatelet and anticoagulant status shapes both the bleeding and the timing question.

Ventricular function on the recent echocardiogram is the single number most worth knowing before induction. It sets how much hypotension the induction can afford and whether inotropic support is a contingency or a plan.

2. Lines and monitoring

An arterial line before induction, central venous access, urinary catheter with temperature, and transesophageal echocardiography in most centers. Processed EEG and cerebral oximetry vary by institution.

Five-lead ECG with ST analysis earns its place in this case more than in any other: the thing you are watching for in the pre-bypass window is ischemia, and ST trend is the continuous form of that question. Positioning is supine with arms tucked and both chest and leg conduit sites prepped — once draped, access to everything runs through lines placed beforehand.

3. Induction and the pre-bypass window

This is the interval the case is built around. The coronary disease is present, the grafts are not yet, and the hemodynamic goals are the ones that protect a supply-limited myocardium. Watch for:

• New ST change, a new wall motion abnormality on echo, or hemodynamic deterioration — ischemia in the window where the disease is present and the fix is not.
• Sternotomy, conduit harvest and cannulation each carry their own stimulus and their own hemodynamic consequence.

4. Going on bypass

Anticoagulation is given, confirmed by activated clotting time, and announced before cannulation. The announcement is part of the procedure, not courtesy: the surgeon cannot cannulate on an unconfirmed ACT.

5. The arrested interval

The anesthetic does not pause because the heart has. Three things change at once:

• Awareness prevention shifts to the pump — the volatile agent is no longer being delivered by your machine.
• Ventilation stops with the lungs deflated.
• Pressure management becomes a negotiation with the perfusionist rather than something you control alone.

Glucose rises on bypass regardless of whether the patient is diabetic; insulin management is protocolized in most units.

6. Separation

Worked as a list, in order: rhythm, rate, contractility, afterload, then flow handed back, with pacing available. Reperfusion after cross-clamp release is a classic moment for malignant arrhythmia.

The failure mode to have thought about in advance is failure to separate: a ventricle that cannot carry the circulation despite pacing and inotropes, escalating toward mechanical support.

7. After bypass

Protamine is given slowly, with the surgical field watched, because protamine reactions range from hypotension to catastrophic pulmonary hypertension.

Antifibrinolytics are standard in most centers, and blood is in the room rather than in the building. Bleeding after protamine is surgical, coagulopathic, or both — and transfusion decisions are made against laboratory and viscoelastic data rather than by sight. Re-exploration for bleeding is a known endpoint of the case, not a surprise.

8. Emergence

Usually not in the operating room. The patient leaves sedated and ventilated for intensive care, where warming completes, bleeding declares itself or does not, and extubation follows a protocol measured in hours. Fast-track extubation pathways vary by institution.