Hemodynamic changes during total-body cooling and rewarming phase in neonates with hypoxic-ischemic encephalopathy

IntroductionNeonatal hypoxic-ischemic encephalopathy (HIE) is a major cause of neonatal morbidity and mortality. Therapeutic hypothermia (TH) is the standard neuroprotective intervention; however, it significantly influences cardiovascular function, necessitating careful hemodynamic monitoring.AimTo evaluate hemodynamic changes in term neonates with HIE during therapeutic hypothermia and the subsequent rewarming phase using serial echocardiographic assessment.Materials and methodsThis prospective observational study included 32 term neonates with suspected perinatal or intrapartum hypoxia admitted within 6 hours of birth. All patients underwent whole-body TH followed by controlled rewarming. Hemodynamic evaluation was performed using serial echocardiography at predefined time points during cooling and after rewarming. Cardiac troponin I levels were measured at admission, during cooling, and after rewarming, and compared with levels in healthy neonates.ResultsSerial echocardiography demonstrated significant changes in cardiovascular function across the cooling and rewarming phases. Cardiac output, left ventricular output, fractional shortening, right ventricular output, and tricuspid annular plane systolic excursion showed significant changes over time, with several measures of ventricular systolic function improving after rewarming. Myocardial performance indices also decreased over time, indicating changes in global ventricular performance. Superior vena cava flow and pulmonary artery pressure increased during cooling and remained elevated during the early post-rewarming period. Inferior vena cava collapsibility and right ventricular systolic/diastolic indices also showed significant changes across the study period. Cardiac troponin I levels did not differ significantly between the cooling and post-rewarming measurements (0.19 ± 0.02 vs. 0.20 ± 0.02 ng/mL, P = 0.825). Correlations between echocardiographic parameters and clinical severity markers, including pH, Apgar score, and Sarnat stage, were variable.ConclusionTH induces significant but reversible alterations in cardiac function in neonates with HIE. Serial echocardiographic assessment provides valuable insights into these dynamic changes and may support individualized cardiovascular management during both cooling and rewarming phases. Larger multicenter studies with longer follow-up are needed to determine their clinical significance and relationship with neonatal outcomes.