## Cardiovascular Effects of IV Induction Agents | Agent | BP Change | HR Change | SVR | CO | Mechanism | |-------|-----------|-----------|-----|----|-----------| | **Etomidate** | **Minimal (±5%)** | **Minimal** | **Preserved** | **Preserved** | Minimal sympathetic depression; direct myocardial effects offset by sympathetic activation | | Propofol | ↓↓ (15–30%) | ↑ (reflex) | ↓↓ | ↓ | Peripheral vasodilation + myocardial depression | | Thiopentone | ↓↓ (10–20%) | ↑ (reflex) | ↓ | ↓ | Direct myocardial depression + vasodilation | | Ketamine | ↑ (10–20%) | ↑ (10–20%) | ↑ | ↑ | Sympathomimetic (catecholamine release); maintains airway reflexes | **Key Point:** Etomidate is the gold standard induction agent for hemodynamically unstable patients because it maintains blood pressure, heart rate, and cardiac output better than any other IV induction agent. **High-Yield:** Etomidate's cardiovascular stability is due to preservation of sympathetic tone and minimal direct myocardial depression. It is the agent of choice in septic shock, cardiogenic shock, and hypovolemia. **Warning:** Single-dose etomidate causes transient adrenal suppression (inhibits 11β-hydroxylase), but this does NOT contraindicate its use in acute settings. Prolonged infusions (>8 hours) are associated with adrenal insufficiency and should be avoided. **Clinical Pearl:** In a critically ill, hypotensive patient requiring intubation, etomidate 0.2–0.3 mg/kg IV is the safest induction choice.
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