Abstract 1755 Poster Session I, Saturday, 5/1 (poster 18)

Purpose: 1) To evaluate factors associated with successful use of inhaled nitric oxide (iNO) in neonates with hypoxemic respiratory failure. 2) To report the hospital outcomes of a diverse sample of neonates treated with iNO. Methods: The primary inclusion criterion was use of iNO for hypoxemic respiratory failure. Neonates with serious congenital heart disease were excluded. Data on demographic and outcome variables from 20 centers was collected, checked and entered into a database. Data queries were sent to each center for missing or incorrect data. Patients were classified as iNO therapy successes or failures. Treatment failure was prospectively defined (see results). Pretreatment characteristics and outcome data were summarized by group (iNO success or iNO failure) and univariate analyses using Chi-square and T-test were performed to evaluate factors associated with iNO success. Multivariate logistic regression was performed to determine what factors were most important in predicting treatment success. Results: Two hundred patients have been reported, 111 patients had complete and checked data. Seventy (63%) neonates were classified as iNO successes and 41 (36%) as iNO failures. Treatment failures were: 22 neonates had no response and needed ECMO; 10 had no sustained response (<4 hrs); 8 had improved oxygenation but were treated with ECMO, and 1 had a toxic methemoglobin level. Of the 111 neonates, 30 (27%) were treated with ECMO; 13 (12%) died; 15 (14%) required oxygen at 30 days of age and 13 (12%) had signs of brain injury (intracranial hemorrhage, seizures, atrophy, or infarct). The median time to iNO failure was 6 hrs (range, 0-108 hrs). There were no differences in the two groups in EGA, birth weight, Apgar Scores at 5 mins, age iNO started, gender, or direction of atrial or ductal level shunts. Neonates with congenital diaphragmatic hernia were the least likely to respond (5/11, 55%) and neonates with RDS were most likely to respond (18/23, 78%). However, the response rates were not statistically different across all diagnoses. At initiation of therapy, neonates in whom iNO worked had higher PaO2/FiO2 ratios than neonates in whom iNO failed (60±6 vs. 40±7, p=0.01). There were no pretreatment differences between groups in pH, PaCO2, or ventilator settings. Both groups were on similar iNO doses at 1 hr of therapy (27 vs. 28ppm). When compared to patients in whom treatment failed, patients responding to treatment and avoiding ECMO were more likely to survive (97 vs. 73%, p<0.01) and less likely to develop chronic lung disease (10 vs. 24%, p=0.07). Conclusions: This is the first multi-center report of a large sample of neonates treated under different iNO protocols. In this data set, severity of lung disease as assessed by the PaO2/FiO2 was more important than age at start of therapy in determining response. This work is supported in part by a grant from iNO Therapeutics, Inc.