Hypothermia

Question 1

Criteria for cooling?

Answer 1

>= 36 weeks who are =< 6 hours old and meet A or B and C

Consider in >= 35 weeks

A. cord pH =< 7.0 or BE >= -16 OR

B. pH 7.01-7.15 or base deficit -10 to -15.9 on cord gas or blood gas within 1 H AND

1. Hx of acute perinatal event (such as but not limited to cord prolapse, placental abruption or uterine rupture) AND
2. Apgar score =< 5 at 10 min or at least 10 min of PPV

C. Evidence of moderate-to-severe encephalopathy, demonstrated by presence of seizures OR at least one sign in 3 or more of the 6 categories below:

Cooling may be deferred if an infant’s neurological status has fully returned to normal within 30-45 minutes after birth

Question 2

Exclusion criteria for cooling in neonates

Answer 2

• moribund infants/infants with congenital or genetic abnormalities
• severe IUGR
• significant coagulopathy
• severe head trauma or intracranial bleeding

Question 3

Side effects of hypothermia

Answer 3

• sinus brady (HR 80-100)
• hypotension (possibly need inotropes)
• PPHN with impaired oxygenation
• mild thrombocytopenia
• prolong bleeding time
• subcutaneous fat necrosis with or without hypercalcemia

Question 4

Stop hypothermia and rewarm if:

(happens in <10% of cases)

Answer 4

• hypotension despite inotropic support
• PPHN with hypoxemia despite adquate treatment
• clinically significant coagulopathy despite treatment

Question 5

Infants with HIE at risk for:

Answer 5

• arrhythmia
• anemia
• leukopenia
• hypoglycemia
• hypokalemia
• urinary retention
• coagulopathy

Question 6

How do you provide hypothermia for neonates?

(start from community hospital)

Answer 6

COMMUNITY HOSPITAL

• Passive cooling while awaiting transport (remove hat, blanket, and turn off overhead warmer)
  
  • do not use ice packs
  • monitor temp q15 min to ensure temp doesn’t decrease below 33

COOLING

• Two setups:
  
  • whole body cooling to rectal temp 33.5 +/- 0.5
    
    • recommended preferentially
  • Head cooling to 34.5 +/- 0.5
• Cool for 72 hours
• Rewarm over 6-12 hours; by 0.5 q1-2 hours
  
  • if seizures and worsening of clinical encephalopathy —> recool for 24 hours
• Brain imaging
  
  • once rewarming has finished, on day of life 4 or 5
  • Consider repeat on DOL 10-14 when imaging and clinical features discordant or when diagnostic ambiguity persists
• Follow up at 18-24 months with multi-D team

Question 7

What percent of babies with HIE post cooling have CP or severe disability

Answer 7

• CP or severe disability > 30% of HIE affected newborns
• cognitive deficits, vison, sensorineural hearing loss, epilepsy

Question 8

How do you rewarm a baby post cooling?

Answer 8

• Rewarm over 6-12 hours; by 0.5 q1-2 hours
• if seizures and worsening of clinical encephalopathy —> recool for 24 hours

Question 9

What are adjunctive therapies to cooling in neonates with HIE?

Answer 9

• Analgesic
  
  • Longer serum clearance of morphine, fentanyl, and midaz
  • low infusion of morphine =< 10 mcg/kg/h or equivalent opioid is recommended as initial approach
• Antiepileptic
  
  • use cautiously but treat neonatal seizures
  • serum levels in first 72 hours
• Minimal enteral feeding (10-20 ml/kg/d) during hypothermia
  
  • more than minimal feeds not safe because decreased gut perfusion
• Aim for normal everything
  
  • Minimize fluctuations in CO2, avoid hyperoxia, ensure adequate tissue perfusion with appropriate pressors/inotropes, normal BG, treat hyperbili, minimize handling