Retrospective analysis of hematological parameters in newborns undergoing therapeutic hypothermia

This study was conducted to investigate how hematologic parameters are affected in infants born asphyxiated and treated with therapeutic hypothermia (TH), which is one of the causes of serious mortality and morbidity during and after the neonatal period. Our other aim was to investigate the effects of TH treatment on these parameters and to investigate the effect of the obtained data on the degree of asphyxia, mortality, morbidity and prognosis. The study was retrospectively conducted with neonates hospitalized with the diagnosis of hypoxic ischemic encephalopathy (HIE) in the Neonatal Intensive Care Unit of Aydın Adnan Menderes University Hospital between January 2018 and June 2023. According to Sarnat and Sarnat staging, the patients were divided into two groups as stage 2-3 (moderate-severe) HIE and received therapeutic hypothermia and stage 1 (mild) HIE and did not require therapeutic hypothermia treatment and their files were retrospectively analyzed. Demographic and clinical characteristics, laboratory parameters and imaging results were analyzed and compared between two groups. The hematologic parameters of the patients were compared at different times during the neonatal intensive care unit admission and after the application of therapeutic hypothermia, and the effect of therapeutic hypothermia on these parameters was investigated. The effects of the obtained data on the degree of asphyxia, mortality, morbidity and prognosis were analyzed. According to Sarnat and Sarnat staging, 149 patients were included in the study, including 90 patients with stage 2-3 (moderate-severe) HIE and 59 patients with stage 1 (mild) HIE. When the complete blood count parameters at postnatal hours 0-6 during hospitalization were compared according to the stages of the patients, the lymphocyte count was found to be significantly higher in the moderate-severe HIE group compared to the mild HIE group (p=0.025). There was no significant difference in NLR (neutrophil-lymphocyte ratio), MLR (monocyte- lymphocyte ratio), TLR (platelet lymphocyte ratio) during hospitalization between moderate to severe HIE and mild HIE groups (p=0.374, p=0.079, p=0.432). In the moderate-severe HIE group, leukocyte count, neutrophil count, monocyte count, platelet count (p<0.001) and eosinophil count (p=0.015) measured at the end of postnatal day 3 after TH to evaluate the effect of TH were found to be significantly lower than before TH, while MLR and TLR were found to be significantly higher (p<0.044 and p>0.001, respectively), no significant change was found in NLR. To evaluate the effects of TH on hematologic parameters, complete blood counts on postnatal day 3 after TH were also compared between the two groups. On postnatal day 3, platelet count was found to be significantly lower in stage 2-3 HIE group compared to stage 1 HIE group (p=0.005). The relationship between hematologic parameters and EEG findings and cranial MRI findings were analyzed in terms of the adverse short-term outcomes of HIE. In patients who had seizures and used antiepileptic drugs, platelet counts were found to be significantly lower on days 5-14 (p=0.032). Neutrophil count and NLR were significantly higher in patients with abnormal EEG on day 5-14 (p=0.024). Eosinophil count on day 1 was significantly higher in patients with abnormal cranial MRI (Magnetic Resonance Imaging) findings (p=0.035). When the relationship between hematologic parameters and mortality was examined in our study, neutrophil counts were significantly lower on day 1 (p=0.040) and platelet counts were significantly lower on days 1 and 3 (p=0.036 and p=0.002). While TLR was significantly lower on the third day (p=0.05), no significant change was found in NLR and MLR in the lost patients. When the relationship between hematologic parameters and prognosis was examined in our study, lymphocyte count at the end of the third postnatal day was significantly higher (p=0.038) in the moderate-severe HIE group with neurodevelopmental retardation. In patients with neurodevelopmental retardation, platelet counts measured at different times were found to be significantly low in all of them (p=0.001 for postnatal days 1 and 3, p=0.008 for postnatal days 5-14). In patients with neurodevelopmental retardation, TLR was significantly lower at different times (p=0.016 for day 1, p=0.003 for day 3, p=0.008 for days 5-14). It was concluded that hematologic parameters may be affected by the therapeutic hypothermia in newborns undergoing therapeutic hypothermia and that these hematologic parameters evaluated at different times may help clinicians to predict the severity of asphyxia, mortality and morbidity. Key Words: Hypoxic ischemic encephalopathy, Lymphocyte, Neutrophil, Neutrophil-to-lymphocyte ratio, Perinatal asphyxia, Platelet, Platelet-to-lymphocyte ratio.