Beneficial Effects 

• Inhalation Keeps Vasodilation Selective to the Pulmonary Vasculature that is Better Ventilated
• Improved Ventilation-Perfusion (V/Q) Matching and Arterial Oxygenation
  • Blood Flow is Preferentially Directed to Better Ventilated Areas
• Decreased Intrapulmonary (Right-to-Left) Shunting
• Decreased Pulmonary Vascular Resistance, Reducing Right Ventricular Afterload

Side Effects

• Typically Has Minimal Systemic Effects
• Increased Preload Can Worsen Cardiogenic Pulmonary Edema from Left Heart Failure
• Small Anti-Platelet Effect (Clinical Impact is Unclear)

Indications

• ARDS with Worsening Oxygenation Despite Lung-Protective Ventilation Strategies
  • *Improves Oxygenation in Severe ARDS but No Proven Mortality Benefit
• Decompensated Pulmonary Hypertension
• Acute Right Heart Failure
• Hypoxemia Due to Pulmonary Vasoconstriction

Contraindications

• Left-Sided Heart Failure

Agents

• Nitric Oxide
  • Potent Vasodilator
  • Starting Dose: 20 ppm (Initial and Maximal Dose) and Subsequently Weaned Down Over the Following Days Once Stabilized
• Aerosolized Epoprostenol Sodium (Flolan/Veletri)
  • Synthetic Prostacyclin Causes Vasodilation
  • Generally Much Less Expensive than Nitric Oxide
  • Starting Dose: 50 ng/kg/min (Initial and Maximal Dose) and Subsequently Weaned Down Over the Following Days Once Stabilized
• Less Common Agents:
  • Nitroglycerine – Metabolized to Nitric Oxide
  • Milrinone – Phosphodiesterase Inhibitor
• *All Have Similar Efficacy but Nitric Oxide and Epoprostenol Can Be Precisely Titrated Making Them Better Suited for Prolonged Maintenance Therapy