Pulmonary arterial hypertension (PAH) represents one of the most formidable comorbidities in anesthesia, owing to its complex pathophysiology and extreme sensitivity to perioperative stressors. Even seemingly stable patients possess profoundly reduced cardiopulmonary reserve, and anesthetic interventions—including airway manipulation, reduced functional residual capacity, increased intrathoracic pressure, and vasodilation—can precipitate sudden hemodynamic collapse. This chapter provides an in-depth analysis of PAH for anesthesiologists, integrating molecular physiology, right ventricular (RV) mechanics, pulmonary vascular biology, and advanced perioperative management strategies. Using a structured, systems-based, and evidence-driven approach, the chapter covers classification, risk stratification, pathophysiological mechanisms, diagnostic evaluation, anesthesia-specific considerations, intraoperative strategies, ventilation science, hemodynamic support, and postoperative care. Algorithms, drug tables, monitoring plans, and early warning signs are incorporated to create a high-utility reference for anesthesia practitioners.

After completing this chapter, the anesthesia practitioner should be able to:

1. Explain the fundamental physiology of the pulmonary circulation and right ventricle in health and PAH.

2. Identify the pathophysiologic determinants of elevated pulmonary vascular resistance (PVR) and their relevance in anesthesia.

3. Describe the WHO classification of pulmonary hypertension and integrate diagnostic investigations into clinical anesthesia planning.

4. Recognize high-risk features in PAH patients undergoing non-cardiac surgery.

5. Develop a structured preoperative evaluation and optimization strategy.

6. Select appropriate induction and maintenance agents based on RV physiology and PVR implications.

7. Implement lung-protective, RV-protective ventilatory strategies.

8. Use vasopressors, inotropes, and pulmonary vasodilators effectively and safely.

9. Manage acute RV failure using physiologically grounded algorithms.

10. Provide high-quality postoperative care with emphasis on early detection of decompensation.

Pulmonary arterial hypertension (PAH) is a progressive disorder marked by sustained elevations in pulmonary artery pressure and pulmonary vascular resistance (PVR). For anesthesiologists, PAH is one of the highest-risk cardiovascular comorbidities encountered in the perioperative period. While advances in medical therapy have improved survival, PAH patients remain physiologically fragile, particularly when exposed to the hemodynamic perturbations of anesthesia and surgery.

The perioperative period introduces multiple threats:

• Airway manipulation → hypoxia and sympathetic stimulation

• Induction of anesthesia → vasodilation and loss of sympathetic tone

• Mechanical ventilation → increases in intrathoracic pressure and PVR

• Surgical stress → catecholamine surges, inflammation, and altered preload

• Fluid shifts → RV overload or underfilling

• Pain, acidosis, hypoventilation → precipitous increases in PVR

Even minor deviations in oxygenation, pH, or carbon dioxide can create profound increases in PVR, overwhelming a right ventricle already operating near the limits of compensation. RV failure can occur abruptly and is associated with high mortality.

The anesthesiologist’s objective is therefore clear:
Protect the right ventricle.
This requires deep integration of physiology, vigilant monitoring, and precise anesthetic technique.

This chapter examines these principles comprehensively, building from...