Methods
This prospective study included a total of 102 cases, comprising 51 infants admitted to a tertiary level Neonatal Intensive Care Unit with a diagnosis of NE and treated with hypothermia between January 2019 and June 2020, and a control group of 51 healthy newborns. Before the study, written informed consent was obtained from the parents of the patients who participated in the research. Approval for the study was granted by the Ethics Committee of Harran University Medical Faculty (Approval date: 07.01.2019, Session 1, Number: 19.01.03). All procedures were applied in compliance with the Helsinki Declaration.
Inclusion Criteria: All cases included in the perinatal asphyxia group were admitted to our unit for the application of therapeutic hypothermia treatment. Therapeutic hypothermia was administered to patients born at ≥36 weeks, aged ≤6 hours, had cord blood or blood gas taken within the first hour after birth showing a pH value of ≤7.00 and/or with base deficit ≥16 mmol/L, had a 10-minute Apgar score of <5, had an ongoing need for resuscitation and showed signs of medium or heavy encephalopathy in the clinical evaluation. In both the clinical assessment and the follow-up period, aEEG findings were also taken into account.15,16
Exclusion Criteria: Infants were excluded from the study if they were aged > 6 hours, were born before the 36th week of pregnancy, weighed under 2000 grams, had an uncertain diagnosis or the presence of other documented conditions which could cause neonatal encephalopathy, congenital metabolic diseases, a diagnosed energy deficiency in the family with a sibling’s medical history and other accompanying diseases together with early encephalopathy, who were thought to be unlikely to benefit from the treatment, had severe or extensive parenchymal cranial hemorrhages, severe life-threatening coagulopathy, maternal chorioamnionitis, trisomy’s, multiple organ anomalies, bacterial growth in blood cultures taken within the first 72 hours of life and/or were suspected of having early-onset neonatal sepsis.15-16
All patients included in the perinatal asphyxia group received TH treatment. A total of 51 patients underwent TH with the whole body cooling system. Therapeutic hypothermia was applied using the Arctic Sun® 5000 Temperature Management System as servo-controlled whole body cooling with a rectal temperature probe targeting a rectal temperature of 33.5°C. After 72 hours of cooling, 7 hours of re-warming was applied (maximum temperature rise of 0.5 ° C / hour) and the session was finished when the body temperature reached 36.5°C.
In the control group, blood samples were taken within the first 0-6 hours after birth from healthy, term infants who were given to their mothers following the birth and whose physical examination showed no pathological findings. In addition, there were no pathological findings during pregnancy of the mothers of these babies.
Blood Withdrawal and Analysis: Blood samples of 2mL were taken from all the cases studied for 0-6 hours postpartum and from cases with hypothermia diagnosed with NE only at 24 and 72 hours. Whole blood count analysis was performed on the samples obtained using an automated blood count device (Abbot Celldyn 3500 Ill, USA). As a result of the complete blood count analysis, leukocyte, neutrophil, lymphocyte, thrombocyte and MPV values were obtained.
Data Analysis: Statistical analyses were performed using SPSS version 24.0 software (SPSS Inc, Chicago, IL, USA). Descriptive statistics were summarized as number, percentage, mean, and standard deviation values. Normal distribution of the variables was checked visually (histogram and probability charts) and using analytical methods (Kolmogorov-Smirnov test). Data showing normal distribution were analyzed using the Independent Samples t-test. The analysis of skewed variables was performed using the Mann Whitney U-test. The repeat measurements of the perinatal asphyxia groups were compared with the Paired Samples t-test. Categorical variables were analyzed using the Pearson Chi-square test. Specificity and sensitivity analysis were performed by using receiver operating characteristic (ROC) curve analysis technique. In the ROC analysis, the area under the curve (AUC) values were studied. A value of p<0.05 was accepted as statistically significant.