Whole-body hypothermia for hypoxic-ischemic encephalopathy (HIE)

Screening criteria

Screen term infants for eligibility if they had poor respiratory effort at birth and needed resuscitation or appear encephalopathic.

Inclusion criteria

Infants > 36 weeks and > 1800 grams with Perinatal Depression (Part A) and HIE (Part B).

Part A: Physiologic criteria for acute perinatal depression:

1) Cord gas or first postnatal blood gas at < 1 hour of age with either pH <7.0 or base deficit > 16 mmol/L.

OR

2) If cord gas or first postnatal blood gas at < 1 hour of age has either a pH of 7.01 - 7.15 or a base deficit of 10 - 15.9 mmol/L or if a blood gas is not available then the following additional criteria are required.

  1. An acute perinatal event (e.g., late or variable decelerations, cord prolapse, cord rupture, uterine rupture, maternal trauma, hemorrhage, abruptio placenta, etc.) and either:
  1. Apgar score of < 5 at 10 minutes or
  2. ii. Need for ventilation initiated at birth and continued for at least 10 minutes

Exclusion criteria

  1. Inability to initiate cooling by 6 hours after birth.
  2. Known chromosomal anomaly (excluding Trisomy 21, Turners, etc).
  3. Presence of major congenital anomalies.
  4. Infants in extremis for whom no additional intensive therapy will be offered.

If an infant meets either criteria A1 or A2, proceed to Part B (neurological criteria and exam).

Part B - Neurological criteria: Infants meet criteria if either seizures or HIE is present.

Evidence for HIE:

Moderate/severe hypoxic-ischemic encephalopathy (HIE) will be defined as either seizures or in the absence of seizures, the presence of signs in 3 of 6 categories from the neurological exam.

Neurological Criteria Table
Category Moderate Encephalopathy Severe Encephalopathy
1. Spontaneous activity Decreased activity No activity
2. Posture

Distal flexion or complete extension or frog-legged

 Decerebrate

3. Autonomic system

Pupils
Heart rate
Respirations

Constricted
Bradycardia (< 100 BPM)
Periodic breathing

Skew deviation/dilated/non-reactive
Variable HR
Apnea or ventilated
4. Tone

Hypotonia (focal or general)
Hypertonia

Flaccid
Rigid

5. Primitive reflexes

Suck
Moro

Weak
Incomplete

Absent
Absent
6. Level of consciousness

Lethargic (decreased activity, arousable, responsive to stimuli)

Lethargic (decreased activity, arousable, responsive to stimuli)

Timing of the examination:

The exam should be done in the first 1 - 3 hours of life once the patient’s cardiopulmonary status has been stabilized.

Performance of the neurological examination for Whole Body Cooling:

The neurological examination should take 10 - 15 minutes to complete and be performed by the attending and/or fellow. The exam is to be recorded in the admit note and performed in the following order: Spontaneous activity, posture, autonomic system, tone (via ROM), primitive reflexes and level of consciousness (response to stimuli).

Patients who have HIE as defined by seizures will still need to have a neurological exam for cooling performed and documented.

If the infant meets physiologic criteria A1or A2 and neurologic criteria B without exclusion criteria, then whole body cooling can be initiated by ordering “Cooling per protocol”.

Reference: N Engl J Med 2005; 353:1574-84.