Cool to be Cold: Induced Hypothermia in TBI

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Cool to be Cold Induced Hypothermia in TBI
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Brain

• Brain temperature is 2 - 4 degrees higher than
  body temperature
• As the temperature rises there is an increase in
  metabolic rate of brain cells
• A Normal temperature is essential in any
  individual with brain injury

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Temperature Control

• Skin surface contains temperature sensing cells
• Hypothalamus
• Thermoregulatory control center
• Individual set point
• First response to overheating is sweating
• First response to cold is shivering
• Metabolic heat production increases to raise temp

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Clinical Studies

• Cardiopulmonary arrest
• 40-50 of in hospital cardiac arrests witnessed
  (Mortality 65-90)
• Mild hypothermia beneficial in witnessed arrest,
  brief interval lt15 minutes, Ventricular
  Fibrillation to Ventricular Tachycardia, In the
  Emergency Department within 60 minutes
• TBI
• Aimed at reducing secondary injury
• GCS 5 or 6 on admit
• Favorable outcome 29 vs. 8
• Mortality 52 vs. 76

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What happens in hibernation?
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• Maintains normal cell function with
• Reduced metabolic rate
• Reduced heart rate and respiratory rate
• Reduces energy needs

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So why use hypothermia?

• By slowing the metabolic rate the body has
• Reduced oxygen needs
• This will in turn
• Reduce intracranial pressure
• Limit secondary injury to the brain

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Induced mild hypothermia

• 32 - 34 Centegrade (89.6 93.2 Fahrenheit)
• Within 4 hours
• Duration 24 - 48 hours
• Intravenous cooling to reduce shivering

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Inclusion Criteria

• General
• Age 18 or greater
• Systolic Blood pressure can be maintained gt 90
  (may be with fluids low-moderate dose
  pressors)
• Traumatic Brain Injury
• Glasgow Coma Score lt 8
• Able to initiate therapy within 4 hours of
  trauma
• Refractory Increased Intracranial Pressure
• Intracranial pressure gt 30 despite maximal
  medical therapy

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Problems associated with Hypothermia

• Lowers heart rate and blood pressure
• Reduces cardiac output
• Difficulty in normal formation of clots
• Increase bleeding tendencies
• Reduces resistance to infection
• Thermal discomfort - Shivering

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Exclusion Criteria

• Infection
• Platelet count lt 75,000/mm3
• Medical instability related cardiac dysrhythmias
  before initiation of hypothermia
• Pregnancy

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Exclusion Criteria

• Known, pre-existing significant clotting problems
  or bleeding tendencies
• Patient has known hypersensivity to hypothermia
  (Raynauds Disease, Sickle Cell disease)

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Guidelines

• Adequate sedation shivering control
• All patients intubated and ventilated
• Standard ICU monitoring
• NG tube/Foley catheter/Arterial line
• Foley temperature probe

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Patient Monitoring

• Continuous monitoring of heart rate, Blood
  Pressure Oxygen saturation
• Temperature
• Every 15 minutes during hypothermia induction
• Every 30 minutes hypothermia maintenance
• Check blood Sugar every 6 hours

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Labwork

• Every 4 hours X3
• BMP Mg level
• Daily (until 24 hrs after return to normal
  temperature)
• ABGs, CBC with diff, BMP, Mg, Phos, Serum
  osmolarity, PT/INR/PTT, Troponin, CPK
  Bld/Urine/Sputum CX

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Induction Maintenance

• Within Emergency prior to intravascular cooling
• Refrigerated saline
• Bolus 1 liter of refrigerated 0.9 normal saline
  over 30 minutes PRN temperature greater than 34
  C (93.2 F).
• May repeat using 500cc bolus, up to 2 liters

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• Hypothermia blanket
• Use hypothermia blanket until intravascular
  cooling line place and system up and running.
• Remove once intravascular cooling initiated

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Maintenance

• Intravascular cooling (ALSIUS Coolgard )

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Coolgard System

• Intravascular cooling
• Programs target temperature and rate which
  temperature is reached
• Triple lumen catheter
• (3) microtherm balloons
• Cool saline flows through the catheter and
  balloons
• Blood flows by balloons cooling blood
• Cools from the inside out thus less shivering

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Current studies

• RhinoChill System
• Uses nasal passageway
• close proximity to the brain
• A natural heat exchanger

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Ice Lavage

• Enteric cooling
• 250 cc ice water per NG
• Clamp NG for 15 minutes
• To low intermittent suction for 15 minutes
• Repeat as needed

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Surface Cooling

• Hypothermia blanket
• Place on cooling blanket sheet between patient
  and blanket
• Set hypothermia unit at 4.0C (39.2F) initiate
  alternative cooling methods

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Surface Cooling

• Ice Water baths/Ice ETOH baths
• Ice packs to venous pools
• Arm pits, back of neck, groin
• Shivering suppression
• Propofol (sedative)
• Midazolam (sedative)
• Vecuronium (paralytic)

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Medications

• Pain Management
• Fentanyl
• Medications to maintain blood pressure
• Phenylephrine
• Dopamine
• Levophed
• Miscellaneous medications
• Tylenol scheduled every 4 hours or PRN
• Potassium Supplement - goal potassium 3-3.5

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Patient Management Issues

• DVT Prophylaxis
• SCDs
• Heparin SQ (unless contraindicated)
• Nutrition
• May attempt if the patient is able to tolerate
  HOB continuously at 30 degrees
• Hold feedings if residuals gt 200ml
• Resume when residuals lt 100 ml

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• Serum Potassium
• Do not provide supplement unless K lt 3.0 mmol/l
  or cardiac instability
• Target K 3.5/cardiac stability

Hypokalemia is expected with hypothermia as
potassium moves into the cell, as the patient is
re-warmed there will be a rebound effect,
therefore aggressive supplement of K is nor
recommended.
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Re-warming process

• Re-warm 0.3 0.5per hour
• Current trend is 0.1 C per 1-2 hours
• Set machine the desired rate of warming
• Wean Vecuronium
• Wean off Propofol
• Wean Midazolam
• If sedation indicated maintain a modified Ramsey
  score of 4
• Resume if shivering occurs
• Hold potassium supplements 8 hrs prior to
  re-warming

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General Issues

• Intact central thermoregulation center makes it
  difficult to lowering body temperature
• The intravascular cooling devices maintains
  temperature goal via alternating cooling
  heating cycles

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• Femoral catheter more effective in cooling
  (larger vessel)
• Mitten Socks if having difficulty with
  shivering keep hands feet covered
• Deviation in temperature in a couple of degrees
  lower increases risk of cardiac arrhythmias
  bradycardia

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Future

• Additional clinical trials in TBI
• Early onset to cooling
• Field
• Emergency Room

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Case Study

• 21 year female lost control of her car
• Unresponsive at the scene
• In the Emergency Room
• Airway placed
• Intracranial pressure (ICP) monitor placed
• Increases in her ICP noted with minimal
  stimulation despite sedation

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• Cooled to 91 degrees for 10 days with good
  control of ICP
• Given paralyzing drugs, sedation, pain
  medications during this time
• Tracheostomy GT placed
• Gradually re-warmed over 24-38 hour period

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• After re-warming process ICP stable localizing
  to stimuli
• Transferred out of the ICU and eventually to
  rehab
• Following simple commands tracking environment

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• After discharged continued in out patient
  rehabilitation
• Returned to school Massage therapist
• Continual problems
• Memory
• Year of 2006 in bits pieces
• Overall memory difficulties
• Mood
• decrease patience, labile emotions

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• Did hypothermia help her?
• Why did she recover?
• Will she ever return to her old self

All are unknown . We only know that she
recovered despite unbelievable odds
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• References
• Clifton, G L. (2004). Is keeping cool still hot?
  An update on hypothermia in brain injury. Current
  Opinion in Critical Care, 10116-119.
• Clifton, G.l., et al. (2001). Lack of effect of
  induction of hypothermia after acute brain
  injury. The New England Journal of Medicine,
  344(8) 556 563.
• Gupta, A.K., Al-Rawi, P.G., Hutchinson, P.J.,
  Kirkpatrick, P.J. (2002). Effect of hypothermia
  on brain tissue oxygenation in patients with
  severe brain injury. British Journal of
  Anaesthesia, 188-192.
• Polderman, K. H. (2004). Application of
  therapeutic hypothermia in the ICU opportunities
  and pitfalls of a promising treatment modality.
  Part 1 Indications and evidence. Intensive
  Critical Care Medicine, 30556-575.
• Polderman, K. H. (2004). Application of
  hypothermia in the intensive care unit
  opportunities and pitfalls of a promising
  treatment modality. Part 2 practical aspects and
  side effects.
• Schwab, S., Schwarz, S. Spranger, M. , Keller, E.
  , Bertram, M., Hacke, W. (1998). Moderate
  hypothermia in the treatment of patients with
  severe middle cerebral artery infarction. Stroke,
  292461-2466.

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Thank you
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