Background: Therapeutic hypothermia is a standard treatment in infants with moderate or severe perinatal hypoxic-ischemic encephalopathy (HIE). Passive hypothermia (PH) is initiated immediately after birth resuscitation and is continued during transfer to the neonatal intensive care unit (NICU). Information regarding the effectiveness of PH in severe HIE infants in the tropics are scarce.

Objective: To investigate body temperature (BT) trends in infants with severe perinatal HIE who received PH after birth resuscitation and during transfer to the NICU in Thailand.

Materials and Methods: The present prospective descriptive study was conducted at Siriraj Hospital, Thailand’s largest national tertiary referral center. PH was commenced in the delivery room in HIE infants that had no contraindications for therapeutic hypothermia. Continuous rectal temperature was monitored from post-resuscitation until NICU admission. BT trend and proportion of infants who reached therapeutic range were observed.

Results: Ten infants had PH commenced in the delivery suite between 2015 and 2018. Mean ± standard deviation birthweight was 2,752.1±70.3 grams. All infants had severe HIE that required intubation during birth resuscitation. Median (min, max) age at PH initiation was 55.0 (7, 343) minutes, and median duration of PH was 42.5 (10, 165) minutes. Mean BT upon NICU admission was 35.9±0.7℃. Seven infants had BT of less than 36.5℃, but none reached therapeutic range (33.0℃ to 34.0℃). BT was significantly lower at NICU admission than at PH initiation (p=0.01). Correlation coefficient between change in BT and duration of PH was 0.5 (p=0.11). No adverse cardiovascular events were observed during PH.

Conclusion: Although 70% of study infants were hypothermic (less than 36.5℃) by the time they were admitted to the NICU, PH therapy was ineffective for inducing hypothermia to within therapeutic range (33.0℃ to 34.0℃) in infants with severe perinatal HIE. A detailed written protocol, an experienced team, and appropriate monitoring devices are recommended when therapeutic hypothermia is indicated in this vulnerable patient population.

Keywords: Body temperature trends, Passive hypothermia, Infants, Severe perinatal hypoxic-ischemic encephalopathy

Received 21 Mar 2019 | Revised 28 May 2019 | Accepted 29 May 2019