A 28-year-old male with acute appendicitis and sepsis (BP 95/60 mmHg, HR 118/min, lactate 4.2 mmol/L) requires emergency surgery under general anesthesia. The anesthesiologist must choose an induction agent. Propofol is contraindicated due to the patient's hemodynamic instability. Which agent should be administered, and what is the most appropriate immediate action after induction?

Explanation

## Clinical Context: Septic Patient Requiring Emergency Surgery This patient has septic shock with hypotension, tachycardia, and elevated lactate. The choice of induction agent is critical because: - Propofol causes severe vasodilation and myocardial depression—contraindicated. - Thiopentone causes profound cardiovascular depression—also contraindicated. - **Etomidate** preserves hemodynamics but causes adrenal suppression—problematic in sepsis. - **Ketamine** maintains airway reflexes, preserves hemodynamics, and provides analgesia—ideal for this scenario. ## Why Ketamine Is the Best Choice **High-Yield:** Ketamine is the induction agent of choice in hemodynamically unstable patients, including septic shock, because it maintains or increases blood pressure and heart rate via sympathomimetic effects. | Agent | Cardiovascular Effect | Airway Reflexes | Analgesia | Sepsis Suitability | |---|---|---|---|---| | Propofol | ↓↓ BP, ↓ HR | Preserved | No | **Contraindicated** | | Thiopentone | ↓↓↓ BP, ↓ HR | Preserved | No | **Contraindicated** | | Etomidate | ↔ BP, ↔ HR | Preserved | No | Relative CI (adrenal suppression in sepsis) | | **Ketamine** | **↑ BP, ↑ HR** | **Preserved** | **Yes** | **Ideal** | **Key Point:** Ketamine is a dissociative anesthetic that maintains sympathetic tone and airway reflexes, making it the safest induction agent in hemodynamic compromise. ## Immediate Actions After Ketamine Induction 1. **Ensure adequate analgesia:** Ketamine provides analgesia but is not a complete analgesic for surgery. Opioids (fentanyl) must be added. 2. **Monitor for emergence reactions:** Ketamine can cause hallucinations, agitation, and dysphoria during recovery. Benzodiazepines (midazolam) reduce this risk. 3. **Maintain hemodynamic support:** Continue fluid resuscitation and vasopressors as needed. 4. **Proceed with surgery:** Unlike propofol or thiopentone, ketamine allows safe induction in septic shock. **Clinical Pearl:** Ketamine's sympathomimetic effects (via catecholamine release and inhibition of reuptake) make it unique among induction agents—it actually supports blood pressure in shock states, unlike all other agents. ## Why NOT the Other Options **Option A (Etomidate):** While etomidate preserves hemodynamics better than propofol or thiopentone, it causes dose-dependent adrenal suppression (inhibits 11β-hydroxylase). In septic patients, adrenal insufficiency worsens outcomes. A single bolus of etomidate may suppress cortisol for 24 hours. Hydrocortisone post-operatively is insufficient—the suppression occurs immediately and during the critical intra-operative period. **Option C (Thiopentone):** Thiopentone causes profound cardiovascular depression (↓↓ BP, ↓ HR) through direct myocardial depression and vasodilation. In a septic patient already hypotensive, thiopentone risks cardiovascular collapse and is contraindicated. **Option D (Defer induction):** Emergency appendicitis with sepsis requires urgent surgical source control. Delaying surgery for 30 minutes risks further deterioration, organ failure, and death. Resuscitation should occur in parallel with induction and surgery, not sequentially. **Mnemonic — Induction Agents in Shock:** - **K**etamine = **K**eeps BP up (sympathomimetic) - **E**tomidate = **E**xcellent hemodynamics but **E**ndocrine risk (adrenal) - **P**ropofol = **P**rofound hypotension (contraindicated) - **T**hiopentone = **T**erribly hypotensive (contraindicated)