What is pulmonary hypertension?

From the Guidelines

Pulmonary hypotension is an uncommon condition that is not a primary clinical concern, and instead, clinicians more frequently encounter pulmonary hypertension, which is elevated pressure in the pulmonary arteries. When dealing with true pulmonary hypotension, the management focuses on treating the underlying cause, which may include volume resuscitation with intravenous fluids like normal saline at 10-20 ml/kg if hypovolemia is present, as seen in various clinical conditions 1. Pulmonary hypotension can occur secondary to systemic hypotension, right heart failure, or after certain medications, and it is essential to understand the different forms of pulmonary hypertension, such as pulmonary arterial hypertension (PAH), which is a clinical condition characterized by the presence of pre-capillary PH and pulmonary vascular resistance >3 Wood units, in the absence of other causes of pre-capillary PH 1. Some key points to consider in the management of pulmonary hypotension include:

• Monitoring blood pressure, heart rate, oxygen saturation, and potentially cardiac output measurements
• Using echocardiography to assess right ventricular function and pulmonary pressures to guide management decisions
• Understanding the comprehensive clinical classification of pulmonary hypertension, which includes different groups, such as PAH, pulmonary veno-occlusive disease, and pulmonary hypertension due to left heart disease 1 The pulmonary circulation normally operates as a low-pressure system, with a normal mean pulmonary artery pressure of 10-20 mmHg, so significant drops can compromise gas exchange and right ventricular function 1. In severe cases of pulmonary hypotension, vasopressors such as norepinephrine (starting at 0.05-0.1 mcg/kg/min) may be needed, and it is crucial to prioritize the single most recent and highest quality study, such as the 2015 ESC/ERS guidelines for the diagnosis and treatment of pulmonary hypertension 1.

From the Research

Definition and Diagnosis of Pulmonary Hypotension

• Pulmonary hypotension is not directly addressed in the provided studies, however, pulmonary hypertension (PH) is defined as a mean pulmonary artery pressure (mPAP) >20 mm Hg, with a pulmonary vascular resistance >2.0 Wood units (WU) 2.
• The diagnosis of PH requires right heart catheterization to assess mPAP and pulmonary vascular resistance.

Treatment of Pulmonary Embolism

• Anticoagulants such as warfarin, unfractionated heparin (UFH), and low-molecular-weight heparins are used to treat pulmonary embolism 3.
• Newer oral anticoagulants like rivaroxaban, dabigatran, and apixaban provide alternative therapeutic options for long-term anticoagulation 3.
• Enoxaparin monotherapy without oral anticoagulation is a feasible treatment option for acute symptomatic pulmonary embolism 4.

Management of Hypotension

• Hypotension can be a sign of significant underlying pathology and requires rapid identification and treatment to prevent organ injury 5.
• Treatment of hypotension is best targeted at the underlying etiology, with expedited bedside evaluation and rapid initiation of treatment 5.

Management of Mild Pulmonary Hypertension

• The management of mild pulmonary hypertension (mPAP 21-24 mm Hg and pulmonary vascular resistance 2-3 WU) requires particular consideration, as clinical trials have used the classical hemodynamic definition of PH 2.
• Practical information tailored to clinicians without training in PH is necessary for the management of mild PH 2.

Anticoagulation Choice in Hospitalized Patients with Pulmonary Embolism

• Despite guideline recommendations, there is increasing use of unfractionated heparin (UFH) in hospitalized patients with acute pulmonary embolism 6.
• Factors associated with anticoagulant selection include agnosticism regarding choice of anticoagulant, inertia of learned practice, therapeutic momentum after anticoagulation initiation, and institutional culture and support 6.