Cooling Of Neonates With Suspected HIE At TCH Guidelines For Treatment
Management guidelines for students, interns and registrars on a variety of routine and emergency situations in our neonatal service at Tygerberg Children’s Hospital. Published in 2014.
Criteria for considering treatment with cooling
When is cooling not appropriate?
Neonates with suspected birth asphyxia who have spontaneous respiration by 30 minutes of age should be assessed to determine whether they meet the criteria for cooling (Criteria A & B below), and should be discussed with the attending consultant.
Criteria for considering treatment with cooling
A. Infants >36 completed weeks gestation with at least one of the following:
- Apgar score of ≤7 at 10 minutes
- Continued need for resuscitation, including endotracheal or mask ventilation, at 10 minutes after birth
- Acidosis within 60 minutes of birth (defined as any occurrence of umbilical cord, arterial or capillary pH <7.00)
- Base Deficit ≥ 16 mmol/L in umbilical cord or any blood sample (arterial, venous or capillary) within 60 minutes of birth
Infants that meet criteria A should be assessed for whether they meet the neurological abnormality entry criteria (B):
Seizures or moderate to severe encephalopathy, consisting of:
- Altered state of consciousness (reduced or absent response to stimulation) and
- Abnormal tone (focal or general hypotonia, or flaccid) and
- Abnormal primitive reflexes (weak or absent suck or Moro response)
The severity of encephalopathy can be assessed using the table below. Infants should have abnormalities in at least 3 categories (e.g. tone, level of consciousness (LOC), reflexes, autonomic function).
| Parameter |
Moderate HIE (Sarnat 2) |
Severe HIE (Sarnat 3) |
| Level of consciousness | Lethargic |
Stupor or coma |
| Spontaneous activity | Decreased Activity |
No activity |
| Posture |
Distal flexion, complete extension | Decerebrate |
| Tone |
Hypotonia (focal or general) |
Flaccid |
| Suck |
Weak | Absent |
| Moro |
Incomplete | Absent |
| Pupils |
Constricted | Deviated, dilated or non-reactive |
| Heart rate |
Bradycardia | Variable |
| Respiration |
Periodic or shallow breathing | Apnoea |
aEEG Assessment
The amplitude integrated EEG (aEEG) should ideally be recorded in all infants with suspected birth asphyxia, preferably before cooling is started. However, cooling need not be delayed until the aEEG is initiated. (Also see aEEG Brainz Monitoring).
A normal aEEG record (confirmed by assessing the underlying EEG and excluding artefact distortion of aEEG) may not necessarily guarantee a good outcome, and should therefore not be used to exclude infants from cooling if they have clear signs of moderate/severe encephalopathy on clinical grounds.
IV anticonvulsant therapy may cause transient suppression of EEG activity. Ideally the aEEG should be commenced before administering anticonvulsant therapy.
When is cooling not appropriate?
Cooling is not appropriate if:
- The infant is likely to require surgery during the first 3 days after birth
- There are other abnormalities indicative of poor long term outcome
Ongoing cooling needs to be reviewed as it may not be appropriate if the infant appears moribund or has persisting extremely severe encephalopathy such that further treatment is likely to be futile, for example if the aEEG/EEG is isoelectric beyond 12-24 hours of age.
Cooling may produce adverse respiratory or cardiovascular effects and should be used with caution in infants with an unstable respiratory or cardiovascular condition (eg. PPHN).
When to start cooling
Cooling should be started as soon as possible after resuscitation is completed, ideally within 6 hours of birth, but can be considered up to 8 hours.
Current evidence suggests that cooling is unlikely to be beneficial if started more than six to eight hours after birth.
Protocol for cooling
If the decision is made to treat with cooling, then the following steps should be followed:
I. Admission
- Arrange admission to NICU if not already in ICU ASAP.
- Switch off radiant/incubator heater - discontinue active warming.
II. On admission to N ICU
- Switch off radiant/incubator heater - discontinue active warming
- Monitor rectal temperature (see nursing guidelines)
- Start CFM/aEEG
- General management as per HIE guidelines.
III. Treatment with cooling
- Follow the Tecotherm system guidelines (see separate sheet)
- Initial mattress temperature set to 28°C – adjust according to response
- Record time of starting cooling, initial temperature, and target date & time for stopping (72 hrs from start).
- NB: Make sure there are 18 pages in observation pack.
- Aim for rectal temp of 33-34°C
- If baby shows signs of distress during cooling (eg. relative tachycardia, shivering), sedation should be considered (if not already on sedation):
- Phenobarbitone 10-20mg/kg, may be repeated up to 40mg/kg. OR
- Lorazepam (Ativan) 0.05mg-0.1mg/kg/dose. OR
- Morphine 50mcg/kg slow IV bolus over 10 minutes, then 50mcg/kg bolus 6 hourly or infusion at 8mcg/kg/hr. Can double dose for +- 6 hours if still distressed, then review.
IV. Re-warming
- Cooling will be stopped 72 hours from when it was initiated. Rate of re-warming should not be more than 0.5 ° C/hour
- If clinical condition deteriorates during re-warming
- Stop re-warming
- Discuss with consultant
When to stop cooling
If a decision is made by the attending medical/nursing team to withdraw intensive care, cooling should be discontinued and, if time allows, the baby re-warmed before intensive care is withdrawn.
Note:
Cooling and re-warming should be completed in NICU.
Ensure all documentation completed before discharge from NICU.