Therapeutic hypothermia

4.5. Therapeutic hypothermia for the infant with hypoxic ischaemic encephalopathy

Pilot studies in animals demonstrated that reducing brain temperature following moderate to severe hypoxic ischaemic encephalopathy (HIE) could reduce the degree of neuronal loss (Gunn, 2000).

There is now Level 1 evidence that inducing hypothermia in term and near term infants with moderate or severe encephalopathy following peripartum asphyxia can reduce the degree of brain injury and long term neurodevelopmental sequelae. (Jacobs, 2010, Azzopardi et al., 2009).

The neuroprotective effects of therapeutic hypothermia, if commenced within 6 hours of birth include:

A reduction in the combined outcome of death or major disability at 18 – 22 months corrected age
A reduction in the number of survivors with cerebral palsy
A reduction in neuromotor delay
A reduction in cognitive delay

The Australian Resuscitation Council guidelines state:

Cooling should be conducted under carefully defined protocols, consistent with those used in the randomized, controlled trials.“(ANZCOR 2016: Guideline 13.9, p. 2).

Any infant who is considered a candidate for therapeutic hypothermia should be discussed promptly with a neonatologist.
Plans should be made for admission to a neonatal intensive care unit.

The following information is from state specific protocols within Australia.

Eligibility criteria:

To be eligible for cooling (active or passive) the infant must meet all of the following criteria:

1. ≥35 weeks’ gestation

2. 1800g birth weight (Victoria and Queensland) or ≥2000g (Tasmania)

3. Less than 6 hours after birth

4. Evidence of peripartum hypoxia-ishaemia as evidenced by the presence of at least two of the following:

* Apgar score ≤5 at ten minutes

* Continued need for resuscitation including positive pressure ventilation (+/- chest compressions) at ten minutes

* Cord pH less than 7.0 or base deficit of 12 or more within 60 minutes of birth.

5. The presence of moderate/severe HIE, defined as seizures OR presence of signs in at least three of the six categories given in the table below.

Category	Moderate Encephalopathy	Severe Encephalopathy
Level of consciousness	Lethargy	Stupor/coma/obtunded
Spontaneous activity	Decreased activity	No activity
Posture	Decorticate: Arms flexed, legs extended	Decerebrate: Arms and legs extended
Tone	Hypotonia	Flaccid
Primitive reflexes	Weak suck, gag & Moro	Absent suck, gag and Moro
Autonomic system Pupils Heart rate Respirations	Constricted Bradycardia Periodic breathing	Dilated/deviated/non-reactive Variable heart rate Apnoea

N.B. Most eligible infants will require or be receiving respiratory support

Exclusion criteria:

Birth weight less than 1800g (Victoria and Queensland) or birth weight <2000g (Tasmania)

Oxygen requirement greater than 80%

Major congenital abnormalities

Uncontrolled clinical coagulopathy (i.e active bleeding)

Survival appears unlikely (this should be discussed with a tertiary neonatologist or a PIPER Consultant)

As cooling must be initiated within 6 hours of birth, referring hospitals are strongly encouraged to seek advice from the neonatal transport team in their state (PIPER-Neonatal in Victoria) or a tertiary centre neonatologist as early as possible to discuss whether an infant meets the criteria for cooling.

Primary considerations before cooling is initiated:

The first priority is to ensure appropriate resuscitation of the newborn, therefore attention to airway, breathing and circulation must take priority over cooling, which is of secondary importance.

All newborns who meet the eligibility criteria should be considered for cooling.

Ideally, a discussion should take place with the parents before cooling is commenced. Prior to talking to the parents, it is strongly recommended that PIPER are consulted to ensure that the newborn meets the criteria for cooling.

Cooling should ONLY be commenced in a non-tertiary Special Care Nursery following discussion with the PIPER Consultant and agreement between PIPER and the referring doctor.

The continuing management of the newborn in whom cooling has been commenced should occur in a tertiary Neonatal Intensive Care Unit (NICU). Therefore all newborns in whom cooling is commenced should be transferred to a NICU by PIPER.

Cooling is only considered for newborn infants who are ≥35 weeks gestation at birth and should not be undertaken for preterm infants born before 35 weeks gestation.

The type of cooling (active or passive) will be determined by the PIPER Consultant in discussion with the referring hospital doctor.

Continuous rectal temperature monitoring with a rectal probe is recommended during cooling. Intermittent axillary temperature monitoring is acceptable whilst awaiting the arrival of PIPER.

Cooling is an adjunct therapy. The ability to commence cooling should NOT influence the decision to cease resuscitation attempts at birth.

There is no evidence to support cooling in:

Infants without HIE or with mild HIE

Premature infants less than 35 weeks’ gestation

Guidelines for cooling in non-tertiary hospitals

Guidelines for cooling have been developed for infants in Victoria, Queensland, Tasmania and New South Wales.

These guidelines contain state-specific:

Eligibility and exclusion criteria for cooling
General management of the infant before cooling is commenced
Observations and monitoring during cooling
Management of potential side effects

The decision to commence cooling in a non-tertiary hospital should always be made in consultation with a consultant neonatologist from the neonatal transport team or a tertiary centre in your state.

Victoria: Neonatal e-Handbook: Better Safer Care Victoria (November 2018)

Therapeutic hypothermia for hypoxic-ischaemic encephalopathy: initiation in special care nurseries

Queensland Maternity and Neonatal Clinical Guideline (March, 2018)

Hypoxic Ischaemic Encephalopathy

Tasmanian Department of Health and Human Services. Royal Hobart Hobart Clinical Guideline (November 2009)

Cooling for Neonatal Hypoxic Ischaemic Encephalopathy_Nov_2009

New South Wales Health: Policy Directive (January, 2010)

New South Wales Health_Whole Body Cooling_Neonates Suspected Moderate or Severe_HIE_2010