The time of initiation of therapeutic hypothermia and the course of hypoxic-ischemic encephalopathy in term newborns

Abstract

Background. The current algorithm for therapeutic hypothermia in full-term infants with hypoxic-ischemic encephalopathy requires the initiation of hypothermia within the first six hours of life. But the question remains unsolved about the possible benefits of early initiation of hypothermia (within the first hour of life), taking into account the different models of the procedure. The aim of our work was to investigate the relationship between the time of initiation of the phase of passive cooling of therapeutic hypothermia and the short-term effects of hypoxic-ischemic encephalopathy. Materials and methods. Analysis of manifestations of hypoxic-ischemic encephalopathy was performed depending on the time of hypothermia initiation: in the first hour of life or during the first 2–6 hours of life. Results. The study included 129 full-term infants with asphyxia at birth, who underwent therapeutic hypothermia (a model of systemic hypothermia using simple means of cooling). Among infants with an early initiation of cooling, the course of hypoxic-ischemic encephalopathy was unfavourable in 27.7 % (23/83) of cases. Among newborns with later initiation of hypothermia, 36.1 % (13/46) of children had an adverse course of hypoxic-ischemic encephalopathy. No significant changes were found between the groups with different time of initiation of passive cooling in terms of the frequency of destructive hypoxic-ischemic brain lesions and fatal cases due to the development of post-ischemic brain edema and multiple organ failure (p = 0.551). Significant differences were observed between the groups in terms of the core body temperature at the time of hospitalization in the neonatal hospital (33.17 ± 0.11 °C vs. 33.85 ± 0.18 °C), the age at reaching the target temperature (4.64 ± 0.65 hours vs. 7.52 ± 1.35 hours), duration of hospitalization in neonatal department (27.3 ± 1.4 days vs. 33.8 ± 2.7 days, p = 0.020). Conclusions. No significant differences were found in the short-term effects of hypoxic-ischemic lesions depending on the initiation of passive cooling within the first 6 hours of life. However, infants, who were passively cooled during the first hour of life, had lower core body temperatures at the time of hospitalization and reached the target cooling temperature faster.