Prospective safety assessment of the acute vasoreactivity test using an inhaled nitric oxide delivery system in pulmonary hypertension.

BACKGROUND

Acute vasoreactivity testing (AVT) is essential for identifying responders to calcium channel blockers in pulmonary arterial hypertension (PAH), and inhaled nitric oxide (NO) is a recommended agent for AVT. However, evidence regarding standardized and safe delivery systems for NO during AVT remains scarce globally. In this study, we prospectively evaluated the safety and hemodynamic effects of AVT using a dedicated inhaled NO delivery system in patients with various forms of pulmonary hypertension.

METHODS

We conducted a prospective, single-arm study on 39 patients with PH who underwent right heart catheterization. AVT was performed with inhaled NO (20 ppm for 10 min) using a dedicated delivery system during the procedure. The primary endpoint was the safety of NO inhalation, defined as the absence of hypotension, hypoxemia due to pulmonary edema, or methemoglobinemia. Hemodynamic changes were secondary endpoints. Outcomes were compared between those with and without PAH.

RESULTS

No major adverse events were observed (hypotension, hypoxemia, or methemoglobinemia; 95 % confidence interval: 0 %-7.4 %). Minor symptoms included transient headache (n = 2) and cough (n = 1). Inhaled NO significantly reduced mean pulmonary arterial pressure (-2.7 ± 3.8 mmHg, p < 0.001) and pulmonary vascular resistance (-56.1 ± 97.8 dyn·s/cm5, p < 0.001). The AVT criteria were met in two (5.1 %) patients with PAH.

CONCLUSIONS

This prospective pilot study demonstrates that AVT using the INOflo system is safe and induces selective pulmonary vasodilation in PAH and selected forms of pulmonary hypertension. These findings provide device-specific safety data supporting the feasibility of standardized NO delivery for AVT in clinical practice.