INHALED NITRIC OXIDE (NO) FOLLOWING RECONSTRUCTIVE SURGERY FOR CONGENITAL HEART DISEASE: FACTORS ASSOCIATED WITH IMPROVEMENT IN GAS EXCHANGE.† 157

Infants undergoing reconstructive cardiac surgery for congenital heart disease (CHD) may develop pulmonary hypertension due to reactive pulmonary vasculature despite technically successful surgery. Inhaled NO reduces pulmonary vascular resistance in this setting. However, optimal dose and duration of treatment have not been correlated with pretreatment status. We investigated if there was time dependency in NO-induced improvement in either arterial oxyhemoglobin saturation (SaO₂) or directly measured pulmonary arterial pressure (P_pa) and if duration of treatment was correlated with perioperative factors. Nine infants with complex CHD, median age 7 weeks(range: 1 day to 17 months), were treated with NO (20-40 ppm) for either severe oxyhemoglobin desaturation (n=7) or for elevated P_pa (n=2) following reconstructive surgery. Eight of nine patients responded, as defined by a rise in SaO₂ of ≥ 5% or by decrease in P_pa of ≥ 10% of baseline. Time to peak SaO₂ response is shown for the responders treated for decreased SaO₂. There was no correlation between duration of need for NO (range of 48-200 hrs.) as determined by daily brief trials without NO and duration of cardiopulmonary bypass (CPB) time (range: 60 to 210 minutes). There was also no correlation between the 0.5 hr. response to NO and the duration of need for NO. Two of nine patients died, including one with pre-treatment SaO₂ of 20% who showed no response and one who demonstrated acute decrease in P_pa. No NO-related toxicity was detected. Inhaled NO can improve gas exchange and pulmonary hypertension acutely following surgery, but the maximum response to inhaled NO may not be achieved for several hours. Neither the initial response to NO nor CBP time predicts duration of need for NO. Table

Table 1