A 52-year-old male with COPD (FEV1 35% predicted) and cor pulmonale is scheduled for elective abdominal aortic aneurysm repair. Intraoperative monitoring shows SpO2 88%, ETCO2 52 mmHg, and mean arterial pressure 78 mmHg. Which of the following induction agents is MOST appropriate for this patient?

Explanation

## Induction Agent Selection in High-Risk COPD with Cor Pulmonale This patient has severe COPD (FEV1 <40%) with established cor pulmonale, presenting with baseline hypoxemia (SpO2 88%) and hypercapnia (ETCO2 52 mmHg). The choice of induction agent is critical to avoid catastrophic hemodynamic and respiratory collapse. ### Why Ketamine is Correct: - **Preserves airway reflexes** better than other agents - **Maintains spontaneous ventilation** — crucial in severe COPD where loss of respiratory drive can precipitate acute decompensation - **Sympathomimetic effect** — increases HR and BP via catecholamine release; maintains coronary and cerebral perfusion pressure - **Bronchodilation** — direct smooth muscle relaxation and indirect effect via catecholamine release; reduces airway resistance - **Maintains pulmonary vascular tone** — less risk of acute right heart failure in cor pulmonale - **Dose**: 1–1.5 mg/kg IV is standard for induction in hemodynamically compromised patients ### Key Point: In severe COPD with cor pulmonale and baseline hypoxemia, **ketamine is the induction agent of choice** because it is the only agent that preserves respiratory drive, maintains hemodynamic stability, and provides bronchodilation. **High-Yield Mnemonic:** "COPD + Cor Pulmonale = **K**etamine" (Keeps airway, Keeps breathing, Keeps blood pressure) ### Comparison Table: | Agent | Respiratory Drive | Hemodynamics | Airway Tone | Safety in COPD | |-------|-------------------|--------------|-------------|----------------| | Propofol | ↓↓ (apnea) | ↓↓ (hypotension) | Relaxation | Contraindicated | | Thiopental | ↓↓ (apnea) | ↓↓ (hypotension) | Relaxation | Contraindicated | | Etomidate | ↓ (mild) | ↑ (stable) | Relaxation | Relative CI* | | **Ketamine** | **↑ (preserved)** | **↑ (maintained)** | **↑ (bronchodilation)** | **IDEAL** | *Etomidate causes adrenal suppression and lacks bronchodilation. **Clinical Pearl:** In this scenario, even brief apnea from propofol or thiopental could trigger acute hypercapnic respiratory failure, acute cor pulmonale decompensation, and cardiac arrest.