Efficacy of passive hypothermia and adverse events during transport of asphyxiated newborns according to the severity of hypoxic-ischemic encephalopathy

Carreras, Nuria; Alsina, Miguel; Alarcon, Ana; Arca-Díaz, Gemma; Agut, Thais; García-Alix, Alfredo

doi:10.1016/j.jped.2017.05.009

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Original articles • J. Pediatr. (Rio J.) 94 (3) • May-Jun 2018 • https://doi.org/10.1016/j.jped.2017.05.009 copy

Efficacy of passive hypothermia and adverse events during transport of asphyxiated newborns according to the severity of hypoxic-ischemic encephalopathy^☆ ☆ Please cite this article as: Carreras N, Alsina M, Alarcon A, Arca-Díaz G, Agut T, García-Alix A. Efficacy of passive hypothermia and adverse events during transport of asphyxiated newborns according to the severity of hypoxic-ischemic encephalopathy. J Pediatr (Rio J). 2018;94:251-7.

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Objective

To determine if the efficacy of passive hypothermia and adverse events during transport are related to the severity of neonatal hypoxic-ischemic encephalopathy.

Methods

This was a retrospective study of 67 infants with hypoxic-ischemic encephalopathy, born between April 2009 and December 2013, who were transferred for therapeutic hypothermia and cooled during transport.

Results

Fifty-six newborns (84%) were transferred without external sources of heat and 11 (16%) needed an external heat source. The mean temperature at departure was 34.4 ± 1.4 °C and mean transfer time was 3.3 ± 2.0 h. Mean age at arrival was 5.6 ± 2.5 h. Temperature at arrival was between 33 and 35 °C in 41 (61%) infants, between 35 °C and 36.5 °C in 15 (22%) and <33 °C in 11 (16%). Infants with severe hypoxic-ischemic encephalopathy had greater risk of having an admission temperature < 33 °C (OR: 4.5; 95% CI: 1.1-19.3). The severity of hypoxic-ischemic encephalopathy and the umbilical artery pH were independent risk factors for a low temperature on admission (p < 0.05). Adverse events during transfer, mainly hypotension and bleeding from the endotracheal tube, occurred in 14 infants (21%), with no differences between infants with moderate or severe hypoxic-ischemic encephalopathy.

Conclusion

The risk of overcooling during transport is greater in newborns with severe hypoxic-ischemic encephalopathy and those with more severe acidosis at birth. The most common adverse events during transport are related to physiological deterioration and bleeding from the endotracheal tube. This observation provides useful information to identify those asphyxiated infants who require closer clinical surveillance during transport.

KEYWORDS
Birth asphyxia; Hypoxic-ischemic encephalopathy; Neonatal transport; Therapeutic hypothermia; Passive cooling; Thermogenesis

Grade	Clinical items	Clinical signs	aEEG items	aEEG recording^d d The worst aEEG segment of 30 min to 1 h in length before clinical evaluation. Grading: Normal trace: normal continuous voltage pattern (upper margin >10 µV and lower margin >5 µV); Moderately abnormal trace: discontinuous pattern (upper margin >10 µV and lower margin ≤5 µV). Severely abnormal trace: burst suppression pattern (upper margin <10 µV and lower margin <5 µV; often accompanied by bursts of high voltage activity), continuous low voltage (upper margin <10 µV and lower margin <5 µV), or isoelectric pattern (upper and lower margin <5 µV, with no burst of activity).
Mild	Alertness Muscular tone Motor responses Reactivity Clinical seizures	Normal Altered: hypotonia (usually) or hypertonia, Normal or slightly decreased Normal or hiperexcitability: increased myotatic reflexes, tremor and/or myoclonus None	Background amplitude or pattern SWC Electrographic Seizures	Normal or moderately abnormal. Present or absent Absent
Moderate	Alertness Muscular tone Motor responses Reactivity Clinical seizures	Lethargy or moderate stupor^a a Lethargy; difficulty to wake up to noxious stimuli and when awake up maintains the alertness a few seconds (≤6″). ^,^b b Stupor: wake up with great difficulty to noxious stimuli and infant quickly falls asleep. Altered: usually hypotonia Greatly decreased, normal quality Decreased tendon reflexes, weak primitive reflexes Present or absent	Background amplitude or pattern SWC Electrographic Seizures	Moderately or severely abnormal Absent Present or absent
Severe	Alertness Muscular tone Motor responses Reactivity Clinical seizures	Severe stupor or coma^b b Stupor: wake up with great difficulty to noxious stimuli and infant quickly falls asleep. ^,^c c Coma; failure to wake up upon nociceptive stimuli. Altered: hypotonia (usually) or hypertonia Absent or stereotyped. Primary reflexes absent Present or absent Frequent signs of brain stem dysfunction	Background amplitude or pattern SWC Electrographic Seizures	Severely abnormal Absent Present or absent

	Transferred
	67
Gestational age (weeks)^a a Mean ± SD.	38.1 ± 2.2
Birth weight (g)^a a Mean ± SD.	3050.7 ± 617.1
Male gender (%)	44 (65.7)
Growth restriction (%)	7 (10.4)
Cephalic presentation (%)	56 (90.3)
Sentinel event (%)	22 (32.8)
Altered fetal heart rate (NRFS) (%)	44 (68.8)
Emergence cesarean section (%)	48 (71.6)
Meconium-stained liquor (%)	24 (35.8)
Artery pH^a a Mean ± SD.	6.9 ± 0.2
Base deficit^a a Mean ± SD.	22.6 ± 6
Apgar 1 min^b b Median (interquartile range).	2 (0–3)
Apgar 5 min^b b Median (interquartile range).	4 (2–6)
Apgar 10 min^b b Median (interquartile range).	7 (5–8)
Advanced resuscitation (%)	52 (77.6)
Heart rate recovery time^b b Median (interquartile range).	3 (1–10)
Moderate HIE (%)	24 (35.8)
Severe HIE (%)	34 (50.7)
Whole-body hypothermia (%)	59 (88.1)
Hospitalization (days)^b b Median (interquartile range).	9 (3–15)
Death (%)	27 (40.3)

	Total population	Mild HIE	Moderate HIE	Severe HIE	p
	n = 67	n = 9	n = 24	n = 34
Hours since the decision to transfer to admission to our referring NICU (h)^a a Presented as median (interquartile range).	3 (2–4)	3 (2–4.5)	2.5 (1.3–3.9)	3.1 (2–4.3)	0.12
Age on admission (h)^b b Presented as mean ± SD (interquartile range).	5.6 ± 2.4 (4.25–6.5)	5 ± 1.5 (3.5–6.5)	5 ± 1.7 (4–6)	6.2 ± 2.9 (4–7)	0.32
Distance traveled (km)^a a Presented as median (interquartile range).	29 (9–70)	29 (9–75)	29 (9–70)	17 (8.25–75)	0.98
Temperature after stabilization at birth^b b Presented as mean ± SD (interquartile range).	34.7 ± 1.6 (33.7–35.7)	35.2 ± 1.3 (33.5–36.6)	34.5 ± 1.1 (33.8–35.3)	34.6 ± 1.9 (33.7–36)	0.47
Temperature on departure from referring center (°C)^b b Presented as mean ± SD (interquartile range).	34.4 ± 1.4 (33.5–35.4)	35.4 ± 1.3 (34.5–36.6)	34.5 ± 1.1 (33.6–35.2)	34 ± 1.4 (33.4–34.8)	0.02
Temperature during transport; first time (°C)^b b Presented as mean ± SD (interquartile range).	34.3 ± 1.4 (33.5–35.2)	35.3 ± 0.9 (34.6–36.1)	34.6 ± 1.2 (33.5–35.8)	33.9 ± 1.5 (33.5 – 34.7)	<0.01
Temperature during transport; second time (°C)^b b Presented as mean ± SD (interquartile range).	34.1 ± 1.4 (33.4–35.1)	35.3 ± 0.9 (34.6–36.1)	34.3 ± 0.8 (33.5–35.2)	33.7 ± 1.5 (33–34.3)	0.01
Temperature on admission (°C)^b b Presented as mean ± SD (interquartile range).	34.1 ± 1.3 (33.1–34.8)	34.7 ± 1.1 (34.2–35.6)	34.3 ± 1.1 (33.3–35.2)	33.7 ± 1.3 (32.7–34.5)	0.04

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[1] * Corresponding author. E-mail:agarciaalix@hsjdbcn.org (A. García-Alix).