Pulsed delivery of inhaled nitric oxide to patients with primary pulmonary hypertension - An ambulatory delivery system and initial clinical tests

Background: Inhaled nitric oxide (NO) has been shown to be a selective pulmonary vasodilator in certain patients with primary pulmonary hypertension (PPH). Objectives: The purpose of this study was to design and test a system for delivery of NO to awaken, ambulatory patients with PPH and to evaluate this system in the home setting. Methods: The ambulatory delivery system consisted of a tank of 80 ppm of NO (balance N-2), a modified gas-pulsing device, and nasal cannulas. The pulsing device was set to deliver NO for 0.1 s at the beginning of each inspiration. Results: Using this system, eight patients with PPH were studied with pulmonary artery catheters in place. Inhalation of NO led to significant reductions in both mean pulmonary arterial pressure (PAPm) (51+/-12 to 43+/-10 mm Hg; p=0.001) and pulmonary vascular resistance (PVR) (790+/-285 to 620+/-208 dyne . s . cm(-5); p=0.01). Three of the eight patients had both greater than 20% and greater than 30% decreases in PAPm and PVR, respectively. No exhaled NO or NO2 was detectable in any of the eight patients. One patient was discharged home from the hospital on a regimen of inhaled NO. At 9 months, no adverse effects were noted and the system was working well. Conclusions: Pulsed delivery of inhaled NO to ambulatory patients with PPH, via nasal prongs, is feasible and, in some patients,leads to significant improvement in pulmonary hypertension. Inhaled 09NO, therefore, may have a role in the long-term treatment of patients with PPH.