[Treatment of patent ductus arteriosus in very preterm infants in China].

Objective: To describe the current status and trends in the treatment of patent ductus arteriosus (PDA) among very preterm infants (VPI) admitted to the neonatal intensive care units (NICU) of the Chinese Neonatal Network (CHNN) from 2019 to 2021, and to compare the differences in PDA treatment among these units. Methods: This was a cross-sectional study based on the CHNN VPI cohort, all of 22 525 VPI (gestational age<32 weeks) admitted to 79 tertiary NICU within 3 days of age from 2019 to 2021 were included. The overall PDA treatment rates were calculated, as well as the rates of infants with different gestational ages (≤26, 27-28, 29-31 weeks), and pharmacological and surgical treatments were described. PDA was defined as those diagnosed by echocardiography during hospitalization. The PDA treatment rate was defined as the number of VPI who had received medication treatment and (or) surgical ligation of PDA divided by the number of all VPI. Logistic regression was used to investigate the changes in PDA treatment rates over the 3 years and the differences between gestational age groups. A multivariate Logistic regression model was constructed to compute the standardized ratio (SR) of PDA treatment across different units, to compare the rates after adjusting for population characteristics. Results: A total of 22 525 VPI were included in the study, with a gestational age of 30.0 (28.6, 31.0) weeks and birth weight of 1 310 (1 100, 1 540) g; 56.0% (12 615) of them were male. PDA was diagnosed by echocardiography in 49.7% (11 186/22 525) of all VPI, and the overall PDA treatment rate was 16.8% (3 795/22 525). Of 3 762 VPI who received medication treatment, the main first-line medication used was ibuprofen (93.4% (3 515/3 762)) and the postnatal day of first medication treatment was 6 (4, 10) days of age; 59.3% (2 231/3 762) of the VPI had been weaned from invasive respiratory support during the first medication treatment, and 82.2% (3 092/3 762) of the infants received only one course of medication treatment. A total of 143 VPI underwent surgery, which was conducted on 32 (22, 46) days of age. Over the 3 years from 2019 to 2021, there was no significant change in the PDA treatment rate in these VPI (P=0.650). The PDA treatment rate decreased with increasing gestational age (P<0.001). The PDA treatment rates for VPI with gestational age ≤26, 27-28, and 29-31 weeks were 39.6% (688/1 737), 25.9% (1 319/5 098), and 11.4% (1 788/15 690), respectively. There were 61 units having a total number of VPI≥100 cases, and their rates of PDA treatment were 0 (0/116)-47.4% (376/793). After adjusting for population characteristics, the range of standardized ratios for PDA treatment in the 61 units was 0 (95%CI 0-0.3) to 3.4 (95%CI 3.1-3.8). Conclusions: From 2019 to 2021, compared to the peers in developed countries, VPI in CHNN NICU had a different PDA treatment rate; specifically, the VPI with small birth gestational age had a lower treatment rate, while the VPI with large birth gestational age had a higher rate. There are significant differences in PDA treatment rates among different units.

[A comparison of the clinical diagnosis and outcome in preterm infants with bronchopulmonary dysplasia under two different diagnostic criteria].

Objective: To compare the clinical diagnosis and outcomes of preterm infants with bronchopulmonary dysplasia (BPD) under two different diagnostic criteria. Methods: A retrospective study was performed in 157 preterm infants who were admitted to Neonatal Intensive Care Unit of the Children's Hospital, Zhejiang University School of Medicine from January 2015 to December 2018. Enrolled infants, with gestational age <32 weeks and survived >14 days, met the 2001 National Institute of Child Health and Human Development(NICHD) definition of moderate and severe BPD or died between 14 days of postnatal age and 36 weeks owing to persistent parenchymal lung disease and respiratory failure. The severities of BPD were revaluated according to the 2018 revised definition of BPD proposed by NICHD. Characteristics and outcomes of these infants were compared with the two different diagnostic criteria with t-test, nonparametric test or Chi-square test. Results: In the 157 enrolled infants (100 males), severities of BPD were classified as moderate in 62, severe in 84 and unclassifiable in 11 according to the 2001 NICHD criteria, while grade Ⅰ in 51, Ⅱ in 29, Ⅲ in 66 and ⅢA in 11 infants respectively according to the 2018 NICHD criteria. Duration of oxygen therapy, positive pressure ventilation and endotracheal intubation in grade Ⅱinfants of 2018 criteria were much longer than that in moderate infants of 2001 criteria (80 (65, 95) vs. 65 (59, 77) d, 52 (38, 58) vs.30 (19, 48) d, 10 (2, 17) vs.4 (0, 12) d, Z=-2.995, -3.750, -2.073, all P<0.05). Mortality of moderate and severe infants in 2001 criteria was 10.3% (15/146), while mortality of BPD in 2018 criteria was 16.6% (26/157). Mortality of grade Ⅲ and ⅢA BPD in 2018 criteria was much higher than mortality of severe BPD in 2001 criteria (33.8% (26/77) vs. 17.9%(15/84), χ(2)=5.357, P<0.05). Conclusion: Definition and classification of BPD based on 2001 NICHD criteria may cause missed or unclassified cases, resulting in the underestimation of the morbidity and mortality of infants with severe BPD.

Tyrosine phosphorylation of Kv1.5 is upregulated in intrauterine growth retardation rats with exaggerated pulmonary hypertension.

Intrauterine growth retardation (IUGR) is associated with the development of adult-onset diseases, including pulmonary hypertension. However, the underlying mechanism of the early nutritional insult that results in pulmonary vascular dysfunction later in life is not fully understood. Here, we investigated the role of tyrosine phosphorylation of voltage-gated potassium channel 1.5 (Kv1.5) in this prenatal event that results in exaggerated adult vascular dysfunction. A rat model of chronic hypoxia (2 weeks of hypoxia at 12 weeks old) following IUGR was used to investigate the physiological and structural effect of intrauterine malnutrition on the pulmonary artery by evaluating pulmonary artery systolic pressure and vascular diameter in male rats. Kv1.5 expression and tyrosine phosphorylation in pulmonary artery smooth muscle cells (PASMCs) were determined. We found that IUGR increased mean pulmonary artery pressure and resulted in thicker pulmonary artery smooth muscle layer in 14-week-old rats after 2 weeks of hypoxia, while no difference was observed in normoxia groups. In the PASMCs of IUGR-hypoxia rats, Kv1.5 mRNA and protein expression decreased while that of tyrosine-phosphorylated Kv1.5 significantly increased. These results demonstrate that IUGR leads to exaggerated chronic hypoxia pulmonary arterial hypertension (CH-PAH) in association with decreased Kv1.5 expression in PASMCs. This phenomenon may be mediated by increased tyrosine phosphorylation of Kv1.5 in PASMCs and it provides new insight into the prevention and treatment of IUGR-related CH-PAH.

[Use of noninvasive high-frequency oscillatory ventilation in very low birth weight infants].

Objective: To evaluate the effectiveness and safety of the use of noninvasive high-frequency oscillation ventilation (nHFOV) in very low birth weight infants. Method: A total of 36 cases received nHFOV between January 2016 and October 2016 in Children's Hospital, Zhejiang University School of Medicine, including 24 males and 12 females, with the gestational age of (27.5±2.5) weeks and birth weight of(980±318)g. The data of the ventilator settings, side effects, and changes of the respiratory function before and after nHFOV were collected and analyzed retrospectively. Nonparametric tests or t tests or χ(2) tests were used. Result: Thirty-two (89%) out of the 36 cases successfully avoided intubation or re-intubation after using of nHFOV. nHFOV was used as the rescue treatment after failure of other noninvasive ventilation in 17 cases, and as the prophylactical treatment preventing re-intubation after extubation in the remaining 19 cases. There were significant decreases in the incidences of apnea and desaturation(SpO(2)<0.85), the level of PaCO(2, )and the FiO(2) 24 h after the initiation of the nHFOV as the rescue therapy((1.2±1.1)vs.(6.3±2.1)episodes , (1.1±1.2) vs.(4.3±1.5) episodes, (43±8) vs.(56±10) mmHg, 0.30±0.07 vs. 0.39±0.11, respectively; 1 mmHg=0.133 kPa, t=7.562, 8.913, 4.179, 3.437 respectively, all P<0.01). No significant changes were found in FiO(2) and PaCO(2) levels 24 h after initiation of nHFOV as the prophylactical therapy after extubation (0.42±0.12 vs.0.40±0.10, (49±8)vs.(48±7)mmHg, t=0.872 and 0.501 respectively, both P>0.05), except for the significant decreases in the mean airway pressure ((7.9±2.6)vs.(9.6±1.6)cmH(2)O, 1 cmH(2)0=0.098 kPa, t=2.198, P=0.041). There were 4 cases suffered from nasal septum injury, while no other nHFOV related complications were noted. Conclusion: nHFOV can be applied in preterm infants as a rescue treatment after the failure of other noninvasive ventilation, or prophylactically used in patients who have high risk of re-intubation.