ADDITION OF NITRIC-OXIDE TO OXYGEN IMPROVES CARDIOPULMONARY FUNCTION IN PATIENTS WITH SEVERE COPD

Study objective: To assess the effect of nitric oxide inhalation on pu lmonary hemodynamics and oxygenation in patients with COPD receiving l ong-term oxygen therapy (LTOT). Design: Prospective study, Setting: IC U of a university medical center. Patients: A total of 18 (6 female, 1 2 male) patients with COPD, spontaneously breathing with LTOT, Interve ntions: Oxygenation and hemodynamic variables were measured and calcul ated at an inspired oxygen fraction (FIo(2)) adjusted to mimic LTO'T c onditions (control), and then 1 h after each sequential addition of 5, 10, and 20 ppm nitric oxide to the gas mixture. A newly developed dev ice (Pulmonox) provided both the delivery and continuous analysis of n itric oxide and oxidative nitric oxide products, Measurements and resu lts: There was a significant improvement in oxygenation at 5 ppm nitri c oxide (PaO2/FIo(2) ratio improved from 244+/-37 to 303+/-59, p<0.05) , but no further improvement at higher doses (ceiling effect). There w as a dose-dependent improvement in hemodynamic variables that was maxi mal at 20 ppm nitric oxide (mean pulmonary artery pressure decreased f rom 29+/-7 to 24+/-5 mm Hg, pulmonary vascular resistance index decrea sed fi om 565+/-321 to 392+/-215 dyne . s . cm(-5) . m(-2) and right v entricular ejection fraction improved from 34+/-6 to 39+/-7%, all p<0. 05), Conclusion: Prior studies have demonstrated that inhaled nitric o xide may improve or worsen oxygenation in patients with COPD. Our data show an unequivocal improvement in oxygenation (albeit with a ceiling effect at 5 ppm) and pulmonary hemodynamics (dose dependent) in COPD patients receiving LTOT, Further studies are warranted to examine the usefulness of inhaled nitric oxide during acute exacerbations of COPD, or even the possibility of long-term application in patients receivin g LTOT.