Feasibility and Safety of Controlled Active Hypothermia Treatment During Transport in Neonates With Hypoxic-Ischemic Encephalopathy

The Association Between Neonatal Intensive Care Unit Arrival Temperatures and Short-Term Outcomes of Neonates with Moderate and Severe Hypoxic-Ischemic Encephalopathy

Therapeutic hypothermia (TH) is the only treatment method that is known to reduce mortality and neurological sequela rates in newborns with moderate and severe hypoxic-ischemic encephalopathy (HIE). We aimed to evaluate the relationship between rectal temperatures measured upon arrival to our unit and short-term outcomes in newborns with HIE/TH. This was a retrospective study conducted between January 2022 and January 2023. The neonates were divided into three groups according to their rectal temperatures measured upon arrival at our unit as follows: Group 1) <33°C, Group 2) 33-34°C (group arriving at target temperature), and Group 3) >34°C. Short-term outcomes and mortality were compared between the groups. Group 1 consisted of 17 (19.8%) neonates, Group 2 consisted of 34 (39.5%) neonates, and Group 3 consisted of 35 (40.7%) neonates who had HIE and an indication for TH. Rectal temperature on arrival to the unit was not related to the rate of clinical convulsions, rates of abnormal attenuated electroencephalography and magnetic resonance imaging findings, rate of pulmonary hypertension, duration of mechanical ventilation and length of hospital stay. Although the mortality rate was 29% in Group 1, it was 3% and 6% in Groups 2 and 3, respectively (p = 0.016). No relationship was found between the rectal temperature upon arrival to the NICU and the short-term outcomes in HIE/TH neonates. However, the mortality rate in those who were overcooled was significantly higher compared with the other groups.

Cooling strategies during neonatal transport for hypoxic-ischaemic encephalopathy

AIM

We reviewed the literature on cooling methods during transport of newborn infants with hypoxic-ischaemic encephalopathy (HIE) born in a non-tertiary centre and transferred to a neonatal intensive care unit for therapeutic hypothermia.

METHODS

The electronic databases CENTRAL, MEDLINE, Embase, CINAHL, and Scopus were searched from inception up to 8 March 2022 for studies comparing cooling versus no cooling, active versus passive cooling, and servo-controlled versus non-servo-controlled cooling. Odds ratio and confidence of interval were calculated for dichotomous outcomes and mean difference and confidence interval for continuous outcomes.

RESULTS

The final analysis included 14 studies, 1 randomised and 13 non-randomised, involving 1098 newborn infants. Compared with the other cooling methods, servo-controlled active cooling was more likely to maintain body temperature within the target range of 33°C-34°C on arrival at a neonatal intensive care unit: odds ratio 13.58, 95% confidence interval 4.32-42.66, risk difference 0.33, 95% confidence interval 0.19-0.46; 224 participants; three studies; I² 0%. The certainty of evidence was low. Only five studies reported mortality rates.

CONCLUSION

Servo-controlled active cooling may be the preferred method during transport of newborn infants with HIE. A future area of focus should be long-term neurodevelopmental outcomes after servo-controlled active cooling.

Therapeutic Hypothermia in Transport Permits Earlier Treatment Regardless of Transfer Distance

OBJECTIVE

Therapeutic hypothermia (TH) is currently the only effective therapy available to improve outcomes in neonates with hypoxic-ischemic encephalopathy (HIE) and has maximal effect when initiated within 6 hours of birth. Neonates affected by HIE are commonly born outside of cooling centers and transport is a barrier to timely initiation. In this study, we sought to determine if the initiation of servo-controlled TH in transport allowed neonates to reach target temperature earlier, without a significant delay in the transfer process, for both local and long-distance transport.

STUDY DESIGN

In this single-center cohort study of neonates referred to a level IV neonatal intensive care unit for TH, we determined the chronologic age at which target temperature was reached for those cooled in transport. Short-term outcome measures were assessed, including survival, incidence of electrographic seizures, discharge feeding method, and length of hospitalization.

RESULTS

In a study population of 85 neonates, those receiving TH during transport (n = 23), achieved target temperature (33-34°C) 77 minutes sooner (230 ± 71 vs. 307 ± 79 minutes of life (MOL); p < 0.001). Locally transported neonates (<15 miles) achieved target temperature 69 minutes earlier (215 ± 48 vs. 284 ± 74 MOL; p < 0.01). TH during long-distance transports allowed neonates to reach target temperature 81 minutes sooner (213 ± 85 vs. 294 ± 79 MOL; p < 0.01). Infants who were cooled in transport discharged 4 days earlier (13.7 ± 8 vs. 17.8 ± 13 days; p = 0.18) and showed a significantly higher rate of oral feeding at discharge (95 vs. 71%; p = 0.03).

CONCLUSION

For those starting TH in transport, time to target temperature was decreased. In our cohort, cooling in transport was associated with improved short-term outcomes, although additional studies are needed to correlate these findings with long-term outcomes.

KEY POINTS

· Therapeutic hypothermia started during transport allows shorter time to target temperature.. · Transfer was minimally delayed by starting cooling in transport.. · Cooling in transport was associated with increased rate of oral feeding at hospital discharge..