Pulsed Delivery of Inhaled Nitric Oxide to Patients With Primary Pulmonary Hypertension: An Ambulatory Delivery System and Initial Clinical Tests

Abstract

Inhaled nitric oxide (NO) has been shown to be a selective pulmonary vasodilator in certain patients with primary pulmonary hypertension (PPH).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.The ambulatory delivery system consisted of a tank of 80 ppm of NO (balance N2), 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.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 x s x 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 N02 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.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.