Timing of Therapeutic Hypothermia & Short-Term Infant Outcomes

Abstract

Background: Hypoxic-ischemic encephalopathy (HIE) can result in devastating long-term neurological morbidity and/or death. Current evidence recommends initiating Therapeutic Hypothermia (TH), as early as possible, however, research specifically describing TH timing in relation to short-term infant outcomes is limited with mixed results. Purpose: Examine TH timing (TH initiation time & time to target temperature) on short-term outcomes (neonatal seizure; brain injury) of infants >35weeks, with suspected HIE, born at a large urban women’s medical center. Methodology: Retrospective, cross-sectional, correlational design examining data extracted from electronic health record from November 1, 2012- March 31, 2020. Descriptive and inferential statistics were performed. Results: Infants with neonatal seizures had higher initial lactates (M=13.39, SD=5.31) a significant difference of 4.38mmol (95% CI -6.89 to -1.86), t(113)=3.44, p=.001; lower arterial blood gas pH values (M=3.331, SD=4.41) a difference of 0.07mEq/L (95% CI, 0.01 to 0.14), t(109)= 2.37, p=.020; fewer minutes to reach target temperature (mean rank=39.11), a significant difference (U= 533, z= -2.677, p= .007). Infants with brain injury had higher initial lactates (M= 13.04 , SD= 5.52) a significant difference of 4.27mmol (95% CI -6.45 to -2.07), t(113)= -3.85, p< .001; lower arterial blood gas pH values (M=7.12, SD= 0.15), a significant difference of 0.09mEq/L (95% CI 0.0 to 0.14), t(109)= 3.16, p=.002. Infants with early initiation had higher initial lactates (M=11.43, SD=4.90) a significant difference of 2.49mmol (95% CI, 0.45 to 4.52, t(113) =2.42, p= .017, Cohen’s d= .607). Infants within target temperature had higher initial lactates (M = 10.57, SD = 5.46) a significant difference of 2.44mmol (95% CI, 0.49 to 4.40), t(113) = 2.47, p= .015, Cohen’s d = .481). Implications: Infants with neonatal seizures and/or brain injury had more acidotic cord and blood gas results, as well as higher initial lactates than those without neonatal seizures and/or brain injury. This study demonstrated the importance of TH timing, specifically time to target temperature, as infants with seizures required significantly less time to reach target temperature. A greater understanding of cord and blood gas results, initial lactates, and target temperature may increase the nurses’ ability to anticipate complications.