EFFECTIVE CONTROL OF PULMONARY VASCULAR-RESISTANCE WITH INHALED NITRIC-OXIDE AFTER CARDIAC OPERATION

Increased pulmonary vascular resistance may greatly complicate the per ioperative management of cardiac surgical patients, Inhaled nitric oxi de may be a promising new therapy to selectively lower pulmonary vascu lar resistance, The purpose of this study was to examine the effects o f inhaled nitric oxide on pulmonary and systemic hemodynamics in cardi ac surgical patients, Twenty patients (age 57 +/- 6 years) were studie d in the operating room after weaning from cardiopulmonary bypass, Mea n pulmonary artery pressure, pulmonary vascular resistance, systemic v ascular resistance, and mean aortic pressure were determined at four p oints of data collection: before nitric oxide, with 20 ppm nitric oxid e, with 40 ppm nitric oxide, and after nitric oxide, Statistical analy sis was by analysis of variance; significance was accepted for p < 0.0 5, Inhaled nitric oxide produced selective pulmonary vasorelaxation, P ulmonary vascular resistance was lowered from 343 +/- 30 before nitric oxide to 233 +/- 25 dynes . sec(-1). cm(-5) with 20 ppm nitric oxide, Pulmonary vascular resistance was not further lowered by 40 ppm nitri c oxide (p < 0.05), Mean pulmonary arterial pressure was 29 +/- 1 mm M g before nitric oxide and was lowered to 22 +/- 1 mm Mg by 20 ppm nitr ic oxide and 21 +/- 1 mm Mg by 40 ppm nitric oxide (p < 0.05), Both pu lmonary vascular resistance and mean pulmonary arterial pressure retur ned to baseline after withdrawal of inhaled nitric oxide, Inhaled nitr ic oxide produced no changes in either systemic vascular resistance or mean aortic pressure, We conclude that nitric oxide may be used as an effective pulmonary vasodilator after cardiac operations, It may be p articularly valuable for selectively lowering right ventricular afterl oad in patients with right ventricular dysfunction.