## Hemodynamic Stability in Cardiac Compromise **Key Point:** Etomidate is the induction agent of choice in patients with compromised cardiac function, shock, or severe hemodynamic instability because it maintains sympathetic tone and preserves airway reflexes better than alternatives. ## Mechanism of Hemodynamic Preservation Etomidate maintains blood pressure through: 1. Minimal direct myocardial depression 2. Preservation of sympathetic outflow 3. Maintenance of baroreceptor reflexes 4. Absence of respiratory depression at induction doses ## Comparison of IV Induction Agents in Cardiac Patients | Agent | Hemodynamic Effect | Cardiac Output | SVR | Airway Reflexes | Use in Low EF | | --- | --- | --- | --- | --- | --- | | **Etomidate** | Minimal change | Preserved | Maintained | Preserved | ✓ BEST | | Propofol | Marked ↓ BP | ↓↓ | ↓↓ | Blunted | ✗ Avoid | | Thiopentone | Marked ↓ BP | ↓↓ | ↓↓ | Blunted | ✗ Avoid | | Ketamine | ↑ BP (usually) | Maintained | ↑ | Preserved | ✓ Alternative | **Clinical Pearl:** In this patient with EF 35% (severely reduced), propofol and thiopentone risk profound hypotension and cardiogenic shock. Etomidate's sympathomimetic properties make it ideal. **High-Yield:** Etomidate's only significant drawback is transient adrenocortical suppression (single dose causes ~11 hours of suppression), but this is acceptable in acute perioperative settings and does not contraindicate its use. **Warning:** Do NOT use propofol as a bolus in patients with reduced ejection fraction — the combination of myocardial depression, vasodilation, and loss of sympathetic tone can precipitate cardiogenic shock and cardiac arrest. ## Why Ketamine Is Not First Choice Here While ketamine preserves hemodynamics and airway reflexes, it causes sympathomimetic effects (↑ BP, ↑ HR) that may be undesirable in a patient with CAD and hypertension. Etomidate's neutral hemodynamic profile is superior.
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