What is a nitroprusside (Nitric Oxide Donor) challenge during a right heart catheterization (RHC)?

From the Guidelines

A nipride challenge right heart catheterization is a diagnostic procedure used to evaluate pulmonary hypertension and determine if it is reversible, with the most recent guidelines recommending the use of inhaled nitric oxide as the standard of care for vasoreactivity testing, as stated in the 2015 ESC/ERS guidelines 1. During this test, a catheter is inserted through a vein and guided to the right side of the heart to measure pressures in the heart chambers and pulmonary arteries. The "challenge" component involves administering a vasodilator, while monitoring how the pulmonary pressures respond. Typically, the medication is started at a low dose and gradually increased to a maximum dose as tolerated, with continuous monitoring of blood pressure. A positive response, indicating some reversibility of pulmonary hypertension, is generally defined as a reduction of the mean PAP ≥10 mmHg to reach an absolute value of mean PAP ≤40 mmHg with an increased or unchanged CO, as defined in the 2015 ESC/ERS guidelines 1. This information helps clinicians determine appropriate treatment strategies, as patients with reversible pulmonary hypertension may respond better to vasodilator therapies. The procedure carries risks including hypotension, so blood pressure monitoring is essential, and the test should be performed in a controlled setting with emergency equipment available. Some key points to consider when performing a nipride challenge right heart catheterization include:

• The use of sodium nitroprusside (Nipride) is not recommended as a first-line agent for vasoreactivity testing, due to its potential for producing marked hypotension and thiocyanate toxicity, as noted in the 2022 AHA/ACC/HFSA guideline 1.
• Inhaled nitric oxide is the preferred agent for vasoreactivity testing, due to its safety profile and efficacy, as stated in the 2015 ESC/ERS guidelines 1.
• The test should be performed in a controlled setting with emergency equipment available, and blood pressure monitoring is essential to minimize the risk of hypotension, as recommended in the 2009 ACCF/AHA guidelines 1.
• The results of the test should be interpreted in the context of the patient's overall clinical condition, and used to guide treatment decisions, as noted in the 2015 ESC/ERS guidelines 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Definition of Nipride Challenge

• A nipride challenge, also known as a nitroprusside challenge, is a diagnostic test used during right heart catheterization to assess the responsiveness of the pulmonary vasculature to vasodilators 2, 3, 4.
• The test involves administering sodium nitroprusside (SNP) to patients with pulmonary hypertension to evaluate the decrease in pulmonary vascular resistance (PVR) and mean pulmonary artery pressure (mPAP) 3, 4.

Purpose of the Nipride Challenge

• The primary purpose of the nipride challenge is to identify patients with pulmonary hypertension who may benefit from vasodilator therapy, such as calcium channel blockers (CCBs) 5.
• The test helps to differentiate between precapillary and postcapillary pulmonary hypertension, which is essential for guiding treatment decisions 2.

Procedure and Interpretation

• During the nipride challenge, SNP is administered intravenously, and hemodynamic parameters, such as PVR, mPAP, and cardiac output, are measured before and after the infusion 3, 4.
• A positive response to the nipride challenge is defined as a decrease in PVR of at least 20% 3.
• The results of the nipride challenge can help guide treatment decisions, such as the initiation of pulmonary vascular-targeted therapy, and can also provide prognostic information 2, 3.