Therapeutic hypothermia physiology and evidence Dr Sanjay Wazir - - PowerPoint PPT Presentation

Therapeutic hypothermia – physiology and evidence

Dr Sanjay Wazir Consultant Neonatology Cloudnine hospital Gurgaon

Objectives – hypothermia treatment

 Why hypothermia  Does it work especially the low cost options  How to do it  Which babies to be put into treatment

Global burden

Disease model

So not all babies who did not cry at birth need treatment

Target mechanisms in asphyxia

Multiple interventions have been tried but most have not shown benefit

Hypothermia has a sustained benefit

Temp Range- major trials

 NICHD trial- 33.4 ± 0.4 °C  TOBY trial – 33.5 ± 0.5 °C  ICE trial – 33.8 ± 0.4 °C

This is the basis why most trails have stuck to this range

Phases of cooling

Techniques for therapeutic hypothermia during transport and in hospital for perinatal asphyxial encephalopathy. Nicola J. Robertson, Giles S. Kendall, Sudhin Thayyil

Induction

• Earlier the cooling, better
• utcome
• Passive cooling post reusus
• Neuro exam before induction
• ? Speed of induction
• Overshoot common

Phases of cooling

Maintenance  33-34 C  Prevent fluctuations- servo better  Avoid cold injury to skin  Prevent displacement

• f temp probe

 Nursing  Monitoring

Phases of cooling

Re-warming  Slow 0.2-0.5 C/hr  NO rapid rewarming

 Adult studies-poor

• utcome

 ? Hypotension due to vasodilatation or hyperkalema/hypoglycem ia  Rebound seizures reported  Not reported in RCT’s

 Monitor few hours after normothermia to prevent rebound hyperthermia

Cooling Equipment-manual and semi-automated devices

Techniques for therapeutic hypothermia during transport and in hospital for perinatal asphyxial encephalopathy. Nicola J. Robertson, Giles S. Kendall, Sudhin Thayyil

Cooling Equipment- Automated (servo) devices

Techniques for therapeutic hypothermia during transport and in hospital for perinatal asphyxial encephalopathy. Nicola J. Robertson, Giles S. Kendall, Sudhin Thayyil

Cooling equipment-low cost devices

 Passive cooling  Cool gel/Ice packs  Fans  Water bottles  Phase-changing material

• 18 babies cooled passively
• Room temp 24 C
• Barbiturate, opiates and benzodiazepams

used if temp not coming down

• Then active cooling with cool gel packs
• 4/18 (22%) did not require any active

cooling at all.

• 14 newborns (78%) were actively cooled

with ice packs over a total of 9.6 ± 7.5 hours

Daetwyler K et al. Feasibility and safety of passive cooling in a cohort of asphyxiated newborn infants. Swiss Med Wkly. 2013;143:w13767

Passive cooling

 Thomas et al-Indian Pediatr. 2011 Jun 7;48(6):445-51  Cloth covered ice gel packs in 20 babies-

 Induction achieved -mea±n 52 mins),  stable maintenance 33.01±0.4 and smooth re-warming (0.48±0.07C)

Cool gel/Ice Packs

Monitoring -Clinical

 Temperature- continuous core (rectal/esophageal) and skin

 Record q15 mins for 1st 4 hour, then q1h

 Vitals- continuous HR, SPO2, BP and urine

• utput

 Should have ECG leads,  invasive BP-art line/UA,  Central access (UV) as far as possible,  SPO2 monitoring,  Urinary cath/bag  Record hourly  Change position and check skin for cold injury q4h

Inclusion Criteria for Brain Cooling

A.GA > 35 Wks /Birth Weight > 1800 Gms /<6 Hrs of age

• B. Physiological criteria –Any1 of following

1.ABG (UC/1st postnatal hr) PH<7 or ABE > -12

• 2. Apgar score <5 at 5 min

3.Ventilation required for at Least 10 min

• C. Neurological Criteria :

Seizure or Evidence of Moderate and Severe encephalopathy (3 of 6 criteria in modified Criteria)

MODIFIED SARNAT’S STAGING Shankaran et

• al. NICHD

trial NEJM 2005

OUTBORN

1.GA > 35 wks / Birth Weight > 1800 g/ < 6 hrs of age

• 2. Physiological Criteria – Newborn who did not cry immediately after

Birth/ Required resuscitation/APGAR score < 5 at 5 min(if avail.)

• 3. Neurological Criteria –Seizures or evidence of encephalopathy

The newborn should fulfill criteria 1, 2,and 3.If not ,do not use the product

Department of Neonatology , Christian Medical College, Vellore, India

Exclusion Criteria

 > 6 hours of age  Major congenital abnormalities,  Imperforate anus  significant head trauma or skull fracture  Coagulopathy with active bleeding  Severe PPHN/ possible need for NO  Infants < 1,800g-birth weight

Stopping cooling prior to 72 hours

 Persistent hypoxemia in 100 % oxygen  Life threatening coagulopathy  Arrthymia requiring medical treatment (not sinus bradycardia)  Decision on withdrawal of care-signs of irreversible brain damage

Clinical Monitoring

Heart rate Q 1hrly Respiratory Rate Q 1hrly Blood pressure Q 1hrly Spo2 Q 1hrly –more frequent if hypotensive Rectal Temperature Q 1hrly Skin Temp Q 1hrly Neurological examination At recruitment prior to cooling and q 24 hrly till normal and discharge(Thompson scoring) Urine Output Q 6hrly Skin Beakdown/redness Q 4 hrly

Lab Monitoring

Baseline 24 hrs 48 hrs 72 hrs

• S. Electrolyte

Y Y Blood urea Y Y

• S. Creatinine

Y Y Blood sugar PT/APTT Y Y Y Y Hb, TLC, DLC,Plt. Y Y Y SGOT/SGPT Y ECG When Clinically Indicated HR < 80/min

NEUROLOGICAL MONITORING

 Neurological assessment at least once a day till rewarming- eg Sarnat/Thompson  Formal eg Amiel-Tison/Hammersmith NNE/TIMP (test for infant motor performance) at 1 week or discharge  aEEG  Neuroimaging -Ultra sound/MRI with MRS

ADVERSE OUTCOME

 Sclerema and Subcutaneous fat necrosis  Skin erythema  Pulmonary hemorrhage  Renal failure  Increased blood viscosity- hemoconcentration, hyperviscosity  DIC  Hypoglycemia  Acid-base and electrolyte disturbances  Increased risk of infections  Hypotension- marked decrease in myocardial contractility and cardiac output in experimental animal models  Sudden cardiac arrest, VT,VF  Pulmonary vasoconstriction.

Conclusion

 Asphyxia - huge burden but now interventions for reduction available  Selection of babies is key to optimum outcome  Servo controlled devices are good but expensive  Low cost models are available – look very promising but would need long term data

THANK YOU