690 D.-H. Kim, J.D. Park, H.-S. Kim, et al. Period II (n=31) iNO (n=12) No iNO (n=19) Responders (n=7) Non-responders (n=5) Operation (n=6) No-operation (n=1) Operation (n=1) No-operation (n=4) Operation (n=17) No-operation (n=2) iNO (n=5) iNO (n=1) Survival (n=6) Death (n=1) Survival (n=1) Death (n=4) Survival (n=17) Death (n=2) Fig. 2. Outcomes of pre- and postoperative iNO therapy for neonates with congenital diaphragmatic hernia during period II. significantly from 69% (9 of 13) in P1 to 100% (24 of 24) in P2. clinical no-response group. In total, 7 of 12 patients who received iNO therapy in P2 survived postoperatively. Pre- and postoperative respiratory management Pre- and postoperative respiratory managements during the two periods are summarized in Table 3. The number of patients who received HFOV therapy before operation was not significantly different between the two periods. Howev- er, the mean durations of preoperative intubation and mecha- nical ventilation were significantly longer in P2 than in P1, and the mean duration of preoperative mechanical ventila- tion in survivors was also significantly longer in P2 than in P1 (data not shown, 13.1±7.9 hr vs. 40.6±24.3 hr, p= 0.003). Mean maximal preoperative peak inspiratory pres- sure (PIP), MAP, and FiO2 were not significantly different in P1 and P2. Mean maximal preoperative PIP, MAP, and FiO2 in P2 were measured before iNO therapy. Outcome of patients who received iNO therapy during period II Twelve of 31 patients in P2 received iNO therapy (Fig. 2). Initial OI was above 12 in all patients who received iNO therapy (data not shown). Seven of the 12 were regarded as clinical responders and five as non-responders. Six of the seven patients in the clinical response group underwent operation, and five of the six patients survived after postoperative iNO therapy, and one patient survived without postoperative iNO. Only one of the five patients in the clinical no-response group underwent operation, and survived after postoperative iNO therapy. This patient had the lowest initial OI (=12) in the DISCUSSION Comparisons of survival rates of CDH patients between institutions or periods are difficult and controversial because the spectrum of disease severity is very wide. In recent retro- spective reviews of CDH cases in the United Kingdom (a 13-yr study) and France (a 5-yr study), overall survival rates ranging between 50% and 56% were observed (9, 10). More recently, the Congenital Diaphragmatic Hernia Study Group reported an overall survival rate of 64% based on data from 71 institutions in North America, Europe, and Australia (4). Thus, the overall survival rate of 69% at our institution (a 15-yr study) is similar to or higher than those reported from other institutions (2, 4, 9-11). However, the survival rate of 69% at our institution has not been constant over the 15-yr period. After iNO therapy was introduced in June 1998, we noticed a change in the survival rates of neonates with CDH. Thus, to investigate this change in survival rate, we divided the study cohort into two groups according to the admission date, i.e., prior to (P1) or after (P2) the intro- duction of iNO therapy. Increases in inborn delivery and prenatal diagnosis in P2 can be explained by the fact that prenatal diagnosis has gradually become routine with the advent of frequent screening ultrasonography during preg- nancy, and thus, more mothers with a prenatal diagnosis of CDH are referred to a tertiary-care center equipped with ‘immediate planned care’. No significant difference was observed between the survival