Purpose: This study was performed to determine the clinical features of full-term infants with hypoxemia detected by pulse oximetry and to establish the diagnosis of critical congenital heart disease (CCHD). Methods: We retrospectively reviewed the medical records of neonates who had been admitted to the neonatal intensive care unit within 2 weeks of birth at Korea University Ansan Hospital between January 2013 and October 2017 (n=450). We classified these neonates based on the presence of hypoxemia at admission and investigated neonatal characteristics, initial symptoms, echocardiographic findings, and final diagnosis associated with hypoxemic diseases. Results: Of 450 term infants, 265 infants (58.9%) were identified hypoxemia by pulse oximetry at admission. The most common symptoms of them were cyanosis and tachypnea. Among them, 80.1% of infants (214/265) were diagnosed with respiratory tract disease and 8.3% of infants (22/265) had congenital heart disease. Thirteen infants (13/265, 4.9%) had CCHD and were treated with urgent surgery or transcatheter intervention within 28 days of birth. Majority of infants with respiratory tract disorder were transferred from hospital immediately after birth, but 46.1% of infants (6/13) with CCHD remained asymptomatic after birth and were admitted after 48 hours after birth. In addition, other hypoxemic illnesses were identified as neonatal infectious and neurological diseases. Conclusion: This study showed the importance of assessment in neonates with hypoxemia, including those diagnosed with CCHD. The possibility of CCHD should be considered in the differential diagnosis in neonates demonstrating hypoxemia after 48 hours of birth. A larger prospective study is needed to assess the effectiveness and outcomes of pulse oximetry for neonatal screening in Korea.

Purpose: The aim of this study was to investigate the clinical characteristics of Respiratory syncytial virus (RSV) infection during the neonatal period to provide information that is useful in clinical practice and suggest extension of the palivizumab administration. Methods: Neonates admitted to the National Health Insurance Service Ilsan Hospital neonatal intensive care unit due to respiratory symptoms and for whom multiplex reverse transcription-polymerase chain reaction and multiplex real time-polymerase chain reaction tests were performed between October 2011 and May 2016 were included in this study. Medical records were retrospectively reviewed, and data was collected for 156 neonates. Results: Among the 156 neonates, RSV was detected in 114 (73.1%), non-RSV in 25 (16%), and no virus in 17 (10.9%). The majority were full term infants (92.4%) and peak incidence of RSV infection was in January. Post-natal care center infection was more common in the RSV group (46.6%) than that in the other virus groups (24%, P=0.0243). Clinical symptoms were severe in the RSV group in contrast to that in the non-RSV or others groups. The RSV group frequently needed oxygen therapy (P=0.0001) and the duration of hospital stays were longer (P=0.0001). Conclusion: RSV is a significant cause of respiratory infection in neonates and the severity is higher in contrast to that with other viral causes of infection. Infants in post-natal care centers have a high-risk of developing RSV infections; therefore, palivizumab administration may be considered in this group to prevent hospitalization and reduce the duration of hospital stay.

Purpose: The aim of this study is to examine the tolerability and effect of early high-dose amino acid administration in extremely low birth weight infants (ELBWIs). Methods: This retrospective cohort study included ELBWI (birth weight <1,000 g, n=142). Biochemical, nutritional, and neurodevelopmental data were compared between infants who received conventional low amino acid (LAA; 1.5 g/kg/day) and those who received high amino acid (HAA; 3 g/kg/day) within the first 48 hours after birth. Neurodevelopmental data included weight, height, and head circumference at discharge, 12 to 14 and 18 to 24 months of corrected age and the Korean Bayley Scale of Infant Development II (K-BSID-II) score at 18 to 24 months of corrected age. Results: The HAA group demonstrated higher peak plasma albumin ($3.0{\pm}0.4$ vs. $3.2{\pm}0.5$, P<0.05) and lower serum creatinine ($1.7{\pm}0.9$ vs. $1.4{\pm}0.8$, P<0.05) during the first 14 days than the LAA group. Full enteral feeding was achieved significantly earlier in infants in the HAA group than in infants in the LAA group ($46.2{\pm}23.0days$ vs. $34.3{\pm}21days$, P<0.01). There was no difference between the two groups in the z score changes in all growth indicators from birth to discharge and at 12 to 14 and 18 to 24 months of corrected age, as well as in the K-BSID-II score at 18 to 24 months of corrected age. Conclusion: Aggressive administration of amino acids during the first 2 days of life in ELBWI was well tolerated and correlated with earlier full enteral feeding, but did not improve growth and neurodevelopment.

Purpose: We assessed the influence of antenatal corticosteroid (ACS) on the inhospital outcomes of intrauterine growth restriction (IUGR) infants. Methods: A retrospective study was conducted with singletons born at $23^{+0}$ to $33^{+6}weeks$ of gestation at Seoul National University Hospital from 2007 to 2014. We compared clinical outcomes between infants who received ACS 2 to 7 days before birth (complete ACS), at <2 or >7 days (incomplete ACS), and those who did not receive ACS in IUGR and AGA infants. Multivariate logistic regression using Firth's penalized likelihood was performed. Results: 304 neonates with 91 IUGR neonates were eligible. Among AGA neonates, mortality (adjusted odds ratio [aOR], 0.13; 95% confidence interval [CI], 0.02 to 0.78), hypotension within 7 postnatal days (aOR, 0.20; 95% CI, 0.06 to 0.64), and severe bronchopulmonary dysplasia (BPD) or death (aOR, 0.24; 95% CI, 0.07 to 0.77) were lower in complete ACS group after adjusting for pregnancy induced hypertension and uncontrolled preterm labor. Mortality (aOR, 0.18; 95% CI, 0.04 to 0.78), hypotension (aOR, 0.26; 95% CI, 0.09 to 0.70), and severe BPD or death (aOR, 0.33; 95% CI, 0.12 to 0.92) were also lower in the incomplete ACS group. Among IUGR infants, after adjusting for birth weight and 5-minute Apgar score, inhaled nitric oxide use within 14 postnatal days was lower in both complete ACS (aOR, 0.07; 95% CI, 0.01 to 0.67) and incomplete ACS (aOR, 0.04; 95% CI, 0.01 to 0.37) groups. Conclusion: ACS was not effective in reducing morbidities in IUGR preterm infants.

Purpose: Preterm infants frequently require red blood cell (RBC) transfusions in neonatal intensive care units (NICU). Storage RBCs undergo many changes during storage periods. We aimed to compare the hemoglobin (Hb) correction effect according to the period of RBC storage and investigate the factors influencing Hb correction. Methods: This retrospective study reviewed the medical records of 289 patients who received RBC transfusion more than once in the NICU of Kosin University Gospel Hospital between February 2006 and March 2016. The subjects were classified into two storage groups: short-term (${\leq}7days$, n=88) and long-term (>7 days, n=201), according to the period of RBC storage. We checked Hb levels by complete blood cell count tests conducted within 2 days before and 5 to 9 days after the first transfusion. We compared the Hb difference between the two groups and analyzed the factors influencing Hb correction. Results: Excluding the use of an invasive ventilator, there was no significant difference between the two groups in terms of clinical characteristics. There was no significant difference in the Hb correction effect between the two groups (P=0.537). Birth weight greater than 1,500 g, higher weight at transfusion, and larger volume of transfusion were significant prognostic factors affecting greater changes in Hb. In addition, surgery experience, higher Hb level at transfusion, and additional blood tests were found to be significantly associated with less changes in Hb. Conclusion: The RBC storage period did not affect the Hb correction effect. The Hb correction effect may be diminished in infants with lower birth weight and lower weight at transfusion under unstable clinical conditions.

Purpose: We aim to assess the Bayley Scales of Infant and Toddler Development, third edition (Bayley-III), Adaptive Behavior (AB) and Social-Emotional (SE) scales at 18 to 24 months of corrected age (CA) to examine their associations with school-age cognitive and behavioral outcomes in children born preterm. Methods: Eighty-eight infants born with a very low birth weight (<1,500 g) or a gestational age of less than 32 weeks who were admitted to the neonatal intensive care unit from 2008 to 2009 were included. Of the 88 children who completed school-age tests at 6 to 8 years of age, 37 were assessed using the Bayley-III, including the AB and SE scales, at 18 to 24 months of CA. Correlation, cross-tabulation, and receiver operating characteristic analyses were performed to assess the longitudinal associations. Results: A significant association was observed between communication scores on the Bayley-III AB scale at 18 to 24 months of CA and the Korean version of the Wechsler Intelligence Scale for Children (K-WISC) full-scale intelligence quotient (FSIQ) at school age (r=0.531). The total behavior problem scores of the Korean version of the Child Behavior Checklist (K-CBCL) at school age were significantly negatively related to the Bayley-III SE and AB scales but not to the cognitive, language, or motor scales. Conclusion: Our findings encourage AB and SE assessments during the toddler stage and have important implications for the early identification of children in need of intervention and the establishment of guidelines for follow-up with high-risk infants.

Esophageal atresia (EA) with proximal tracheoesophageal fistula (TEF; gross type B) is a rare defect. Although most patients have long-gap EA, there are still no established surgical guidelines. A premature male infant with symmetric intrauterine growth retardation (birth weight, 1,616 g) was born at 35 weeks and 5 days of gestation. The initial diagnosis was pure EA (gross type A) based on failure to pass an orogastric tube and the absence of stomach gas. A "feed and grow" approach was implemented, with gastrostomy performed on postnatal day 2. A fistula was detected during bronchoscopy for recurrent pneumonia; thus, we confirmed type B EA and performed TEF excision and cervical end esophagostomy. As the infant's stomach volume was insufficient for bolus feeding after reaching a body weight of 2.5 kg, continuous tube feeding was provided through a gastrojejunal tube. On the basis of these findings, esophageal reconstruction with gastric pull-up was performed on postnatal day 141 (infant weight, 4.7 kg), and he was discharged 21 days postoperatively. At 12 months after birth, there was no catch-up growth; however, he is currently receiving a baby food diet without any complications. In patients with EA, bronchoscopy is useful for confirming TEF, whereas for those with long-gap EA with a small stomach volume, esophageal reconstruction with gastric pull-up after continuous feeding through a gastrojejunal tube is worth considering.

Leukocyte adhesion deficiency is a rare primary immunodeficiency and autosomal recessive disorder caused by a mutation in the gene encoding CD18, which is a constituent of leukocyte integrins. Clinical features usually begin with a delay in the separation of the umbilical cord in the neonatal period, and are characterized by marked leukocytosis with infection, delayed wound healing, and repeated bacterial and fungal infections. We experienced a case of leukocyte adhesion deficiency diagnosed in the neonatal period, in which a late preterm infant admitted to neonatal intensive care unit presented with a septic hip. Flow cytometry analysis of whole blood showed a decrease in the expression of CD11b/CD18. This is the first case of leukocyte adhesion deficiency with neonatal septic hip diagnosed in Korea.

Umbilical venous catheterization (UVC) is a common practice in intensive neonatal care. However, a malpositioned UVC and its prolonged use may lead to various problems, including mechanical, infectious, and thrombotic complications in various organs such as the liver, lungs, and heart. Congenital chylous ascites is characterized by abnormally high levels of triglycerides in the peritoneal fluid of newborns, which originate from refluxed lymph within the abdominal cavity. Herein, we report a case of an UVC complication presenting as chyloperitoneum simulating congenital chylous ascites in a preterm neonate that resulted from total parenteral nutrition (TPN) extravasation from a malpositioned UVC. Biochemical analysis of intraperitoneal chylous fluid and TPN infusate could help confirm the origin of chyloperitoneum. This case suggests that TPN extravasation from UVC should be considered when chyloperitoneum develops in newborns with an indwelling catheter. UVC positions must also be carefully monitored at regular intervals to recognize associated complications early, particularly in cases with an inevitably malpositioned catheter related to the anatomy of the vessel course.