WINTHROP UNIVERSITY HOSPITAL: Mild Therapeutic Hypothermia for
Comatose Survivors of out of hospital cardiac arrest
Hypothermia Team:
 MICU attending
 Cardiology Attending
 ICU fellow
 Cardiology fellow
 Neurologist
 MICU nurse manager or designee
 ED nurse manager or designee
 ED attending
 MICU/CCU resident
 Nursing supervisor/ Critical Care Nursing Director or designee
 Critical Care Educator
 Bed Board Nurse
Logistics:
 Priority of MICU bed - within 3 hours
 1:1 nursing X 36 hours
 Maintain cooled saline in ER
 Begin cooling with iced saline, ice packs
 Peripheral IV preferred for cooled NS; if needed, can administer via femoral
central line
 CVP line and arterial line required for continuous CVP and BP monitoring (place
once patient is stabilized)
 Intubation, mechanical ventilation; turn off humidifier (use HME’s only)
 Blood gases do not have to be temperature corrected.+
Background
Increased brain temperature contributes to ischemic brain damage in patients post cardiac
arrest. Studies have shown that lowering temperature by a few degrees decreases
ischemic damage. In studies of out of hospital cardiac arrest, induced hypothermia
protocols have contributed to improved neurologic outcomes.
Goal
If criteria are met, the patient is cooled using induced hypothermia for 24 hours to a T°
32-34°C (89-93° F). Target time to reach goal temperature is less than 6 hours. The 24
hour cooling period begins when the target temperature is reached.
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Preparation
Shivering, our body’s attempt at maintaining homeostasis generates heat, thereby
impairing the ability to achieve the target temperature. Additionally, the resultant energy
expenditure is likely detrimental to the metabolic status of the acutely injured brain.
 When using conventional surface cooling or with the Arctic Sun device it is
necessary to control shivering with the use of specific anti-shivering/sedative
medications.
 If shivering can not be controlled, paralysis may be necessary.
Cooling must be done rapidly (4-6 hours) to achieve maximum effectiveness, and should
be instituted as early as possible. Most studies have found it necessary to use cold saline
infusion, ice packs and cooling blankets to achieve the temperature goal. Other methods
such as ice lavage may be used to help achieve target temperature.
Inclusion Criteria
 Age greater than 18 years
 Cardiac arrest with return of spontaneous circulation (ROSC) within 30 minutes
 Persistent coma as evidenced by no eye opening to pain after resuscitation or a
Glasgow coma scale < 8 (No waiting period required)
 Blood pressure of at least 90mmHg systolic spontaneously or with fluids &/or
pressors
 Intubated and on mechanical ventilation
Exclusion Criteria
 Time to ROSC >30 minutes
 Interval from arrest to CPR 15 minutes
 DNR status
 Temperature < 30°C on admission
 Repeated arrest
 Life threatening arrhythmia
 Active bleeding
 Unable to maintain BP with pressors
 Pregnancy
 Trauma as a cause of cardiac arrest
 Major surgery within 2 weeks
 Sepsis
 Severe Coagulopathy
 Other causes of coma (consider CT/MRI/EEG if clinically indicated)
 Poor pre-morbid cognitive status
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Nursing Instructions
Cooling/Rewarming Protocol (in ER)
 Infuse cooled saline (cooled to 4°C), 2 Liters over 1 hour, to initiate cooling. Cold
saline infusion can be administered via a peripheral line or femoral venous
catheter and can lower temperature by 1-2°C. DO NOT infuse cooled saline via
internal jugular or subclavian catheters. (Caution if renal failure, see below)
 Place ice packs on patient’s axilla and groin until cooling blankets started.
Remove once cooling device is applied to avoid overshoot.
 Monitor vital signs, with particular attention to arrhythmia detection.
Arctic Sun Device for Cooling (see below if Arctic Sun NOT Available).
will be started once patient arrives in MICU.
 Apply pads per sizing chart
 Select auto mode for a goal of 33°C (temperature may vary once goal is met by
0.5 degrees)
 In order for patients to achieve and maintain target hypothermia of 33°C complete
sedation must be achieved with continuous infusion of appropriate medications.
Paralysis may be required if unable to control shivering with anti-shivering
protocol. Sedation goal: Ramsey score: 6, Bedside Shivering Assessment Scale
(BSAS): 0(see below).
Target temp = 33°C, not lower than 32°C not higher than 34°
 Monitor and record patient and water temperature every 1 hour
Water temperature < 10°C indicates active cooling
Water temperature > 20°C indicates no or minimal active cooling
Prolonged or episodic active cooling indicates a febrile response and should trigger
evaluation for a possible site of infection
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Sedation protocol activated
Mechanical Ventilator order set activated
Continuous CVP monitoring
Arterial line monitoring
Continuous temperature monitoring via bladder probe. If anuric, may need rectal
probe or Pulmonary Artery catheter to monitor core temperature.
NG tube
Lacrilube to eyes every 8 hours while sedated/receiving paralytics
VS q 15 minutes during induction of hypothermia
VS q 30 min X 2, then q 1 hours
EKG every 8 hours during cooling
CBC, PT/PTT, CMP, lactate, troponin, amylase, lipase STAT
CBC with diff, platelets, PT/INR, PTT every 12 hours
Renal panel with Magnesium every 8 hours
LFT’s, lactate daily x 3 days
Blood cultures x 2 sets, urine, sputum cultures daily
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Blood pressure and Volume Management
 Target systolic BP > 90mmHg: MAP > 70mm Hg to maintain cerebral perfusion
 IV fluids (normal saline)
 Use vasopressors if necessary (as per order sheet)
Discontinuation of cooling ( after discussion with MICU fellow/attending)
Passively re-warm patient for:
 Refractory hypotension, requiring 2 or more vasopressors
 Refractory arrhythmias
 Uncontrolled bleeding
Medications
Sedation required: titrate sedation to eliminate shivering (see scales below)
To Ramsey Score: 6
To BSAS: 0
Can select from this category of sedatives:
 Propofol
 Midazolam
 Dexmedetomidine
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Use vecuronium (Norcuron) or cisatracurium (Nimbex) as a bolus during
induction. Either repeat boluses or infusion for paralysis can be used if shivering
cannot be controlled with anti-shivering measures.
Anti -Shivering
 Acetaminophen 650 mg every 4-6 hours ATC
 Fentanyl bolus +/-Fentanyl infusion
 Buspirone 30 mg via NGT every 8 hours ATC
 Counter warming: Forced air convection warming blanket (Bair hugger) at 4043°C
 Can add meperidine
 Consider early use of bolus paralytics to control shivering.
Paralysis
 Vecuronium or cisatracurium Consider early use of bolus to control shivering,
o can use repeated boluses or continuous infusion (see order set)
 Sedation must be used if paralytic agents are administered.
 Discontinue paralytics after patient is warmed to 37°
 Discontinue sedation 2 hours AFTER paralytic agent stopped
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Critical Care Orders
 After 24 hours of cooling, re-warm at a rate of 0.2-0.3°C every hour, to target
temp of 37°C
 Maintain temperature at 37°C for an additional 24 hours.
 Stop all potassium administration 8 hrs prior to re-warming, including all
potassium IV fluids. (Rewarming causes rebound hyperkalemia )
 Remove skin pads and assess skin integrity every 4 hours
If Arctic Sun not available- external cooling with cooling blanket and ice
 Eligibility confirmed and materials gathered.
 Obtain two cooling blankets and cables (one machine) to “sandwich” the patient.
The bottom blanket should have a bath blanket covering it to protect patient’s
skin. Place the top cooling blanket over a bath blanket.
 Begin sedation with midazolam (Versed ) or Propofol (Diprivan) and institute
sedation protocol as above.
 Pack patient in ice (groin, chest, axilla, side of neck); use additional measures as
needed (see below) to bring patient to goal temperature. Avoid packing ice on top
of chest; that may impair chest wall motion..
 Once goal temperature is reached, ice bags may be removed and the cooling
blankets used to maintain temperature.
Special circumstances:
 Patients with seizures must be on continuous EEG monitoring. Remember to get
head CT to rule out primary CNS event.
 Patients with renal failure- consider giving only 1 L of cooled saline
 DO NOT give cooled saline if there is evidence of fluid overload
 Cool with ice packs, cooling blanket, etc
 Hemodialysis can be done while receiving hypothermia
 Remember to use rectal probe for T° monitoring if anuric.
Bedside Shivering Assessment Scale (BSAS)
 0 – none
 1 – Mild: Neck, Thorax (pectoralis muscles)
 2 – Moderate: Involves upper extremities, neck, face
 3 – Severe: Whole body
Modified Ramsey Sedation Scale
1. Anxious, Agitated, Restless
2. Cooperative, Oriented, Tranquil-accepts mechanical ventilation.
3. Responds to commands only
4. Brisk response to light glabellar tap or loud noise.
5. Sluggish response to light glabellar tap or loud noise.
6. No Response.
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