Cardiac Surgery Induction

Cardiovascular Anesthesia · 9 min read

Cardiac induction is high-stakes — the patient is most vulnerable in the minutes after induction, before the surgical team has access to the heart. Three principles dominate: hemodynamic stability, blunting catecholamine response, smooth transition to maintenance.

Pre-induction setup

BEFORE the patient arrives in OR: large-bore peripheral IV (16g+), arterial line in pre-induction holding (radial, prep alternative side for redo sternotomy with prior CABG harvested vessels), TEE probe + machine in room, induction drugs drawn, esmolol + nicardipine + phenylephrine + epinephrine at hand. PATIENT in OR: standard ASA monitors + 5-lead ECG (II + V5) + arterial line + pulse ox on finger of correct side (away from BP cuff), nasal O2 cannula if planned for awake induction. Defibrillator pads on patient (anterior-posterior for sternotomy access).

Hemodynamic goals

GOAL — maintain MAP within 10-20% of patient baseline + AVOID TACHYCARDIA. Hypotension risk: hypoperfusion of stenosed coronaries → ischemia. Tachycardia risk: increased O2 demand + decreased diastolic filling time → ischemia. The HEART RATE matters more than BP — a HR 100 with MAP 90 is worse than HR 60 with MAP 70 in CAD. PRELOAD — keep adequate; avoid sudden vasodilation. AFTERLOAD — manage based on lesion (low for AR/MR, high for AS). CONTRACTILITY — preserve in CAD; avoid negative inotropes if EF <30%.

Drug selection

Most common cardiac induction recipe (CAD with preserved EF): FENTANYL 5-10 mcg/kg slow over 2-3 min (blunts laryngoscopy response, dose-dependent — higher dose = more stable; cardiac surgery uses higher than general anesthesia). MIDAZOLAM 0.05-0.1 mg/kg (amnesia + synergy with opioid). ETOMIDATE 0.2-0.3 mg/kg OR low-dose propofol 0.5-1 mg/kg (etomidate preferred for hemodynamic stability; single-dose adrenal effect controversial but acceptable). ROCURONIUM 0.6-1.2 mg/kg (intubation; pancuronium is alternative for vagolytic effect to offset bradycardia from high-dose opioid — modern practice often skips). VOLATILE titrated up gradually after intubation. LOW EF (<30%) — opioid-based with minimal hypnotic; consider ketamine 0.5-1 mg/kg for hemodynamic preservation.

Etomidate drug entry →

Laryngoscopy + intubation

BLUNT THE PRESSOR RESPONSE: pre-treat with esmolol 0.5 mg/kg or labetalol 5-10 mg before laryngoscopy (peak HR/BP at 60-90 sec post-intubation, can spike +20-30 mmHg + 10-20 bpm). Lidocaine 1.5 mg/kg IV may add modest blunting. PERFORM LARYNGOSCOPY GENTLY — careful blade placement, avoid prolonged attempts. CONFIRM ETT placement immediately (capnogram), depth (21-22 cm at lip in average adult), bilateral breath sounds. If TEE — operator inserts after intubation, before sterile prep.

Post-intubation transition

After ETT confirmed: sevoflurane 0.7-1.0 MAC titrated, fentanyl infusion if planned, second IV access, central line + PA catheter as indicated, foley, NG tube, warming blanket, antibiotic at incision time. RE-CHECK pressures + treat trends EARLY — don't let hypotension persist. PHENYLEPHRINE 50-100 mcg boluses or norepinephrine infusion 0.05-0.2 mcg/kg/min for sustained hypotension. ESMOLOL 10-30 mg boluses for tachycardia. Update surgeon on hemodynamic stability before they prep.

Special scenarios

AORTIC STENOSIS — "slow + full + tight" — preserve preload, AVOID vasodilation (drops aortic root pressure → coronary perfusion → ischemia → arrest), AVOID tachycardia. AORTIC REGURGITATION — "forward flow" — slight tachycardia (less time for backflow), reduced afterload OK. MITRAL STENOSIS — like AS but want LOW HR (need diastolic filling time). MITRAL REGURGITATION — like AR — forward flow, lower SVR. PULMONARY HYPERTENSION — preserve RV preload, AVOID hypoxia/hypercarbia/acidosis (raise PVR), milrinone + iNO ready. RECENT MI — ischemic; consider ICU admit + delay elective. EF <20% — extreme caution; opioid-only induction often safest.

Pearl — the first 30 minutes

Hemodynamic stability in the first 30 minutes after cardiac induction predicts most of the case. Get it right. If pressure drifts, treat aggressively + early. If HR rises, treat aggressively + early. Communicate frequently with the surgical team — they know the lesion + can advise on fluid + position adjustments. Don't 'wait and see' in cardiac induction — small problems become big problems quickly.

References

· Hensley Cardiac Anesthesia 6e Ch 7 (Induction)
· Miller's Anesthesia 9e Ch 56
· Kaplan's Cardiac Anesthesia 7e