Can vasopressors be used in patients with pulmonary hypertension?

Vasopressor Use in Pulmonary Hypertension

Yes, vasopressors can and should be used in patients with pulmonary hypertension when hemodynamically indicated, but the selection must prioritize agents that maintain systemic vascular resistance (SVR) greater than pulmonary vascular resistance (PVR) to prevent right ventricular ischemia. 1

Fundamental Hemodynamic Principle

The critical concept governing vasopressor selection in pulmonary hypertension is maintaining adequate right ventricular coronary perfusion:

• Right ventricular coronary perfusion occurs during both systole and diastole, unlike left ventricular perfusion which occurs only during diastole 1
• If PVR exceeds SVR during systole, right ventricular ischemia will occur 1, 2
• Higher systolic systemic arterial pressure goals are necessary in pulmonary hypertension patients compared to non-pulmonary hypertension patients to prevent right ventricular ischemia 1

Preferred Vasopressor Strategy

Vasopressin at replacement doses is the recommended first-line vasopressor to offset potential drops in SVR when using inotropes like dobutamine 1. This approach maintains systemic pressure without increasing PVR.

Inotrope Selection

When inotropic support is needed alongside vasopressor therapy:

• Dobutamine, milrinone, and epinephrine have neutral or beneficial effects on PVR 1
• Dobutamine is often preferred over milrinone due to its shorter half-life, which provides better control in the face of potential hypotension 1
• These agents are supported by the literature for use in decompensated pulmonary hypertension with right ventricular failure 3

Adjunctive Pulmonary Vasodilator Therapy

Inhaled nitric oxide (iNO) is recommended for acutely decreasing PVR and improving cardiac output in critically ill pulmonary hypertension patients 1:

• iNO has the advantage of not affecting SVR while selectively reducing PVR 1
• iNO improves oxygenation by augmenting ventilation-perfusion matching and unloading an acutely failing right ventricle 1
• Upon weaning from iNO, a phosphodiesterase inhibitor should be started or restarted as replacement therapy to prevent rebound pulmonary hypertension 1

Intravenous prostacyclin also has support in the literature for acute management 3.

Hemodynamic Monitoring Requirements

Direct hemodynamic evaluation is recommended in critically ill pulmonary hypertension patients 1:

• Central line placement with direct measurement of central venous pressure and mixed oxygen saturation is often necessary 1
• A pulmonary arterial catheter can be useful but is not required 1
• Volume status assessment is notoriously difficult in pulmonary hypertension patients, and non-invasive estimates of central venous pressures may be misleading 1, 2

Critical Pitfalls to Avoid

Intubation and Mechanical Ventilation

Intubation alone can acutely decrease right ventricular preload and increase afterload, potentially precipitating hemodynamic collapse 1. Have vasopressors immediately available before intubating these patients.

Systemic Hypotension

The traditional approach of tolerating lower blood pressures in critically ill patients is dangerous in pulmonary hypertension. Systemic hypotension in the setting of elevated pulmonary pressures creates a pressure gradient favoring right ventricular ischemia 1, 2.

Vasodilator Therapy Contraindications

Patients with advanced pulmonary hypertension and severe right ventricular dysfunction may be unable to tolerate vasodilators due to negative inotropic effects 1. This is particularly relevant when systemic hypotension is present.

No single inotrope or pressor is entirely contraindicated in critically ill pulmonary hypertension patients, but each agent should be considered carefully based on its effects on both systemic and pulmonary vascular resistance 1.

Context-Specific Considerations

Acute vs. Chronic Pulmonary Hypertension

Therapy for acute arterial pulmonary hypertension should be aimed at acutely relieving right ventricular pressure overload and preventing right ventricular dysfunction 4. Cases complicated by right ventricular failure and systemic arterial hypotension require tight hemodynamic monitoring and aggressive treatment including combinations of pulmonary vasodilators, inotropic agents, and systemic arterial vasoconstrictors 4.

Pulmonary Hypertension Secondary to Other Conditions

For patients with pulmonary hypertension resulting from critical illness or chronic lung diseases, treatment should address the primary cause of hemodynamic deterioration, and pulmonary vasodilators usually are not necessary 3. The focus should be on optimizing the underlying condition rather than empiric pulmonary vasodilator therapy.