LOW-DOSES OF INHALED NITRIC-OXIDE IN HEART-TRANSPLANT RECIPIENTS

Background: The purpose of this study was to assess the hemodynamic ef fects of low doses of inhaled nitric oxide in patients after orthotopi c heart transplantation. Methods: Two hours after the operation 10 adu lt patients who were still under anesthetic effects and undergoing mec hanical ventilation inhaled, during 60 minutes, a mixture of nitrogen, oxygen, and nitric oxide (20 ppm). A standard profile of hemodynamic data was collected at baseline, at 30 minutes, at 30 more minutes of i nhalation, and at the same points after nitric oxide suspension. Resul ts: A significant decrease was found from baseline to 60 minutes, imme diately after nitric oxide inhalation in the following: systemic vascu lar resistance index 1268 +/- 409 to 1090 +/- 354 (p = 0.0161); pulmon ary vascular resistance index 252 +/- 124 to 154 +/- 98 (p < 0.05); pu lmonary vascular resistance index/systemic vascular resistance index r atio 0.21 +/- 0.09 to 0.14 +/- 0.08 (p = 0.0025); transpulmonary gradi ent 12 +/- 3 to 9 +/- 3 (p = 0.05). A significant increase was also fo und in cardiac index from 4.2 +/- 1.1 to 4.9 +/- 1.4 (p = 0.0007). Oth er parameters such as mean pulmonary, systemic, wedge and right atrial pressures, in addition to intrapulmonary shunting, heart rate, and ox ygen extraction ratio, did not present any significant changes. The pr ocedure was well tolerated by all patients, and no undesirable effects such as methemoglobin elevation or worsening of pulmonary hypertensio n after nitric oxide suspension were observed. Conclusions: The benefi cial effects observed by inhaled nitric oxide in the pulmonary vascula r resistance index/systemic vascular resistance index ratio, transpulm onary gradient, and cardiac index suggest that nitric oxide acts mainl y in pulmonary territory and could be a possible pulmonary vasodilator agent used to control central hemodynamics after heart transplantatio n.