The dissertation evaluates the frequency and severity of acute renal injury (AKI) according to the criteria of KDIGO neonatal modification in premature infants with HSPDA, to study the features of renal blood flow, renal oxygenation, diagnostic capabilities of renal biomarker NGAL, to identify risk factors for AKI and to develop criteria for early diagnosis of AKI in premature infants with HSPDA. In addition, according to autopsy data to study the morphological features of the kidneys in premature infants with patent ductus arteriosus. To achieve the goal and solve the tasks set, a comprehensive clinical and paraclinical examination of 74 premature infants (gestational age 29 - 36 weeks) was made. The study was open, single-center, prospective, stratified, cohort.
Inclusion criteria: premature infants at 29-36 weeks of gestation with HSPDA, patent ductus arteriosus (PDA), closed ductus arteriosus (CDA), the presence of signed informed parental consent to participate in the study.
Exclusion criteria: congenital malformations, intracerebral and intraventricular hemorrhages of III-IV degree, neonatal sepsis, severe asphyxia in childbirth, skin diseases, intrauterine growth retardation.
Children were stratified by the presence of HSPDA: the first group included 40 children with HSPDA, the second group - 17 children with PDA without hemodynamic disorders, the third group - 17 children with CDA. Additionally, children were stratified by the presence of AKI. Diagnosis and stratification of the severity of AKI was performed according to the criteria of KDIGO neonatal modification. The study period was 10 days. 8 children dropped out of the study due to the development of exclusion criteria: intraventricular hemorrhage of III-IV degree (4 cases), neonatal sepsis (4 cases).
The gestational age of children averaged 32.9 ± 0.22 weeks. The mean birth weight was 1998.2 ± 56.55 g.
According to the results of the study, the presence of HSPDA in premature infants is a factor that affects the severity of AKI. On the fifth or seventh day of life, the development of stage II-III AKI is observed in every third case. Risk factors for the development of AKI were: PDA diameter> 2 mm, the presence of chronic foci of infection, chorioamnionitis in the mother, the dose of ibuprofen 20 mg / kg in the first day of life, the use of furosemide.
Indicators of renal hemodynamics are closely related to the size of PDA in the first day of life. In premature infants with HSPDA, who were diagnosed with AKI on the third day of life, in comparison with children without AKI already on the first day of life there was a significant decrease in peak systolic blood flow and final diastolic blood flow velocity, increase in RI in the interlobar renal artery, which also persists for the third day of life. Non-invasive monitoring of renal oxygenation (RrSO2) by NIRS in preterm infants with HSPDA allowed to establish an inverse correlation between RrSO2 and direct with fractional oxygen extraction (FTOE) on the first day of life and blood creatinine concentration on the third 0.434, p˂0.02). Low renal oxygenation (56.1 ± 4.5%) in the first day of life is associated with the development of AKI on the third day of life in premature infants with HSPDA. The level of NGAL of urine on the first day significantly correlates with the maximum stage of AKI (ρ = 0.76, p <0.001) and the diameter of HSPDA > 2 mm. A correlation between urinary NGAL and RrSO2, FTOE, renal blood flow parameters, especially peak systolic blood flow velocity in the interlobar artery on the first and third day, revealed that these indicators may also be early markers of AKI development.
Morphological features of the kidneys in premature infants with PDA are delayed development of the glomeruli of the subcapsular zone of the cortex, an increase in the of the renal stroma due to of the functional parenchyma, increased hemorrhage into the superficial zone of the renal cortex. Decompensation of the tubular renal system occurs in the presence of PDA ≥ 3 mm.
The binary logistic regression model revealed the most significant predictors of AKI development in premature infants with HSPDA: the maximum blood flow rate in the interlobar renal artery, HSPDA diameter greater than 2 mm and serum creatinine levels in the first day of life.
Key words: acute kidney injure, premature newborns, hemodynamically significant open ductus arteriosus.
