Objective:To systematically analyze the effects of liberal and restrictive red blood cell transfusion strategies on mortality and neurodevelopmental impairment (NDI) of extremely low birth weight infant (ELBWI).Methods:From the establishment of the databases to March 2021, randomized controlled trials on this subject published in English or Chinese from databases (Pubmed, Embase, Cochrane Library, Web of science, Wanfang database, CNKI, VIP and CBM) were searched. The article selection process and data extraction were carried out by two independent investigators. RevMan 5.3 software was used for meta analysis.Results:The literature search yielded 692 pertinent articles and 4 studies were selected for meta-analysis. 3 577 ELBWI were followed up until corrected age of 22~26 months. Meta-analysis showed that restrictive and liberal transfusion thresholds had no significant effects on severe adverse outcomes (mortality+NDI) ( RR=1.01, 95% CI 0.94~1.08, Z=0.24, P=0.81), mortality rate ( RR=1.10, 95% CI 0.94~1.29, Z=1.24, P=0.22), NDI ( RR=0.98, 95% CI 0.89~1.07, Z=0.46, P=0.65) and cerebral palsy ( RR=1.21, 95% CI 0.89~1.66, Z=1.21, P=0.23) for ELBWI. Conclusions:Restricted and liberal blood transfusion have similar long-term effects on mortality and NDI of ELBWI. This may provide certain reference value guiding clinical blood transfusion in ELBWI.

Objective:To study the changes of cord blood neutrophil gelatinase-associated lipocalin (NGAL) under different levels of hypoxia at birth and its correlations with hypoxic organ damage (including liver, kidney and heart).Methods:From April to October 2022, all neonates born in our hospital were prospectively enroll in the study. The neonates without perinatal risk factors were assigned into the control group. The neonates with intrauterine distress or hypoxia during labor were assigned into the hypoxia group (no asphyxia at birth) and the asphyxia group (with asphyxia at birth). Cord blood was collected from the umbilical artery and cord blood gas (CBG) and NGAL were measured. Liver enzymes, kidney function and cardiac enzymes as biomarkers for hypoxic organ damage were measured 24~48 h after birth. The correlations of NGAL and the biomarkers were analyzed.Results:A total of 161 neonates were enrolled, including 91 in the control group, 49 in the hypoxia group and 21 in the asphyxia group. NGAL in the asphyxia group was significantly higher than the hypoxia group and the control group [(1.81±0.71) ng/ml vs. (1.22±0.53) ng/ml, (0.88±0.47) ng/ml], NGAL in the hypoxia group significantly higher than the control group ( P<0.05). NGAL was negatively correlated with Apgar score, pH and BE of CBG ( r<-0.3, P<0.05) and positively correlated with lactate, ALT, creatinine ( r>0.3, P<0.05). No significant correlations existed between NGAL and gender, gestational age, birth weight, mother's age, BMI and CK-MB ( P<0.05). ROC curve showed that sensitivity and specificity of NGAL for predicting hypoxic organ damage were 84.3% and 60.3%, respectively, with a cut-off value of 1.07 ng/ml. Conclusions:Cord blood NGAL may increase with the deterioration of hypoxia at birth and may be associated with hypoxic organ damage.