CONTINUOUS LOW-DOSE INHALED NITRIC-OXIDE FOR TREATMENT OF SEVERE PULMONARY-HYPERTENSION AFTER CARDIAC-SURGERY IN PEDIATRIC-PATIENTS

Objective-To assess the effect of inhaled nitric oxide (NO) on severe postoperative pulmonary hypertension in children after surgical repair of a congenital heart defect. Design-A pilot study of NO administrati on to 7 consecutive children who required adrenergic support and in wh om postoperative mean pulmonary artery pressure was more than two thir ds of mean systemic pressure and persisted despite alkalotic hypervent ilation. Setting-Routine care after cardiac surgery for congenital hea rt disease in a multidisciplinary paediatric intensive care unit. Meth ods-Continuous inhalation of NO, initially at 15 ppm. Thereafter, dail y attempts at complete weaning or at reducing NO to the lowest effecti ve dose. Results-In 6 of the 7 children NO inhalation selectively decr eased mean (SD) pulmonary artery pressure from 51 (12) to 31 (9) mm Hg (P < 0.05) while mean systemic arterial pressure was unchanged (68 (1 0) v 71 (7) mm Hg) (NS) and the arteriovenous difference in oxygen con tent decreased from 6.7 (0.9) to 4.8 (0.8) vol% (P < 0.05). Concomitan tly Pao(2) increased from 158 (98) to 231 (79) mm Hg) (P < 0.05). The seventh child showed no response to NO up to 80 ppm, could not be wean ed from cardiopulmonary bypass, and died in the operating room. In res ponders, attempts at early weaning from NO inhalation always failed an d NO at concentrations of less than 10 ppm was continuously administer ed for a median of 9.5 days (range 4 to 16 days) until complete weanin g was possible from a mean dose of 3.9 (2.9) ppm. Methaemoglobinaemia remained below 2% and nitrogen dioxide concentrations usually ranged f rom 0.1 to 0.2 ppm. One child later died and five were discharged. A f ew months after surgery Doppler echocardiography (and catheterisation in one) showed evidence of regression of pulmonary hypertension in all 5. Conclusions-Inhalation of NO reduced pulmonary artery pressure in children with severe pulmonary hypertension after cardiac surgery and this effect was maintained over several days at concentrations carryin g little risk of toxicity.