Post Cardiac Arrest Induced Hypothermia
Protocol and Procedure
Deborah Heart and Lung Center
Therapeutic Hypothermia Working Group
Purpose:
To improve mortality and neurological outcomes in patients who have survived cardiac arrest.
The goal of therapy is to achieve and maintain therapeutic hypothermia for a 24 hour period
with a target of 33C.
Policy:
Therapeutic Hypothermia (TH) shall be initiated on all adult cardiac arrest patients with return
of spontaneous circulation (ROSC) that fit the inclusion criteria, and does not have any of the
following: eye opening to painful stimuli, pre-existing coma, traumatic arrest (either
penetrating or blunt), body temperature less than 30˚C, or an apparent gravid uterus.
1. Therapeutic Hypothermia will be initiated, when possible, pre-hospital.
2. Upon arrival in Emergency Department or post cardiac arrest in DHLC, a “Code Chill”
will be called through the hospital beeper system. Team will consist of ED Attending or
Floor Attending, Intensivist, ICU Attending, ICU Fellow, ICU Code Nurse and nursing
supervisor. DHLC nursing will attend in an advisory capacity to facilitate transfer into
DHLC system
3. After patient is identified as a candidate, TH will begin immediately in the form of ice
packs to axilla, groin and neck.
4. Protocol will follow procedure outline once patient stabilization and therapies (antiarrhythmics, vasopressors/fluids with target SBP 90-100 mm Hg, and advanced airway
management with O2 sat >85%) are implemented.
5. Patient will be moved to the Critical Care Unit or the Cath Lab (for intervention) as soon
as possible after stabilization with cooling measures in place.
6. Discontinue cooling and begin active rewarming in the presence of any cardiovascular
instability ( i.e. persistent uncontrollable arrhythmias or refractory hypotension), or if
patient awakens.
Inclusion Criteria:
 Nontraumatic cardiac arrest with Return of Spontaneous Circulation (ROSC)
 Cardiopulmonary Resuscitation (CPR) initiated within 10 minutes of cardiac arrest
 ROSC within 30 minutes of recognition of the cardiac arrest; MAP ≥ 60 for at least 30
minutes post ROSC with or without vasoactive medication
 Initiation of Induced Hypothermia begun within 6 hours of collapse
 Initial body temperature must be greater than 30C
 No purposeful movement to command and Glasgow Coma Scale < 6
● Age > 18; Female < 50 must have negative urine HCG
Exclusion Criteria:
 Prolonged arrest time longer than 60 minutes or down time without BLS longer than 10
minutes
 Age less than 18 years
 Pregnancy
 Uncontrolled bleeding, thrombocytopenia or other coagulopathy
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Therapeutic Hypothermia Protocol
 DNR or DNI status
 Severely impaired pre-arrest cognitive status
 Other causes of coma (mass lesions, metabolic coma, seizures, drug overdose, head trauma,
cerebrovascular accident, etc.)
 Existing multi-organ dysfunction syndrome; severe sepsis or co-morbidities with minimal
chance of meaningful survival independent of neurological status; known terminal illness.
 Refractory arrhythmias
 Hypoxemia with Saturation <85% for more than 15 minutes
 Response to verbal commands after return of spontaneous circulation.
Qualifications:
Critical Care physicians caring for the patient will write orders for Therapeutic Hypothermia,
Admission and assess current medications/therapies for continuation during the protocol.
Cardiology, Neurology and Renal consultations should be considered.
 Critical Care registered nurses will manage/continue the cooling blanket temperature
regulation system and initiate hypothermia once patient is within the DHLC system.
Education:
Training will be provided to staff participating in the care of the selected patients.
Family/Patient Teaching:
 Explain the purpose of therapeutic hypothermia
 Explain the potential use of other assistive devices (ventilator, IV pumps, monitors,
Sportbed, pulse oximetry, cooling blankets)
 Explain the use of analgesics, sedatives and neuromuscular blocking agents.
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Therapeutic Hypothermia Protocol
Procedure/Protocol:
Equipment:
Cooling Blankets (2)
Cooling machine, two sets of hoses and temperature probe cable
Sterile/distilled water for cooling machine
Knee high antiembolism hose and SCDs
Ice packs
Rectal temperature probe
Foley catheter with temperature probe and drainage system
2 sheets
3 Liters 0.9NS IVF at 4 C
Large bore IV catheters, tubings and infusion pumps
Cardiac monitor, transducers, pressure system
Pulse oximetry (forehead)
Hands free defibrillator pads
Sportbed with rotation
OGT/NGT and LCS
Obtain
from SPD
Stocked in ICU
Procedure:
 The provision of therapeutic hypothermia to survivors of cardiac arrest consists of three
phases: Induction, Maintenance and Rewarming. This section will outline in detail the
steps to be taken. Specific order sheets and checklists are available. Check orders to
address specific interventions for the following complications of hypothermia: shivering,
hypotension, hypokalemia, hypomagnesemia, and hypocalcemia. Once patient has been
determined to be a candidate, proceed with Induction phase. If patient has STEMI on
EKG, consult cardiology and consider thrombolytic therapy/PCI/ASA administration
Induction with Intravenous Cold Saline and Cooling Blanket
 If temperature 30-33 C, allow patient to warm to 33 C
 Insert arterial line
 Insert CVC (consider PreSep catheter)
 Attach rectal temperature probe to cooling machine. Secondary temperature probe (foley
or other central temp) will be used to correlate cooling temperature probe.
1. Begin IV cold crystalloid as soon as patient is identified and place ice packs in patient’s
axilla and groin while cooling blanket is being readied. 0.9NS at 4 C is stored in
designated refrigerator in the ICU.
2. All fluids used during the cooling and rewarming phase should be dextrose free
3. Follow as ordered either No Cardiac Shock protocol or Cardiac Shock/LV Failure/low EF
protocol for cooling therapy.
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No Cardiac Shock protocol
 Infuse 1500 ml 4 C 0.9NS over 30 minutes
 If core temperature remains > 34.5 C, infuse an additional 500 ml over 30
minutes
 Repeat 500 ml infusions until core temperature  34.5 C to a maximum of 30
ml/kg total
Cardiac Shock/LV failure/low EF is present:
 Infuse 1500 ml 4 C 0.9NS over 60 minutes
 If core temperature remains > 34.5 C, infuse an additional 500 ml over 30
minutes
 Repeat 500 ml infusions until core temperature  34.5 C to a maximum of 30
ml/kg total
4. If unable to obtain target core temperature within 5 hours, contact provider
5. Completely expose patient and place cooling blankets above and below patient with a
sheet between patient and cooling blanket
6. Attach both blankets to the cooling machine.
7. Set cooling machine to autocontrol and goal temperature to 33C
8. Once patient reaches 34C, allow patient to drift down to goal temperature of 33C
9. Be alert for early signs of shivering and initiate shivering protocol
Maintenance with Cooling Blanket Machine
1. Acetaminophen 650 mg OGT/NGT/PR Q 6 hours during induction and maintanence; Q
4 hr. PRN during re-warming phase and for a temperature > 37C after warming. Clamp
NG/OG tube for 30 minutes after administration.
2. Maintain patient temperature at 33 C for 24 hours from initiation of cooling.
3. If patient is in pain or agitated, medicate with as ordered; otherwise sedation should be
limited to facilitate frequent neurologic exam checks.
4. If shivering develops see shivering orders
5. If hypotension develops (MAP  80 mmHg) see BP & Volume Management orders
6. If hypokalemia develops see electrolyte replacement orders
7. If dysrhythmia or bleeding develops see rewarming phase below
8. Maintenance of therapeutic hypothermia should be provided with cooling
blankets and if temperature > 33.5 C, infuse an additional intravenous 4C
0.9NS bolus of 250 ml Q 10 minutes until temperature < 33.5C.
9. Replace urine output every hour with 0.9NSS in a ratio of 1:1 or 0.5:1
BP & Volume Management
For patients on the therapeutic hypothermia protocol who develop hypotension
(MAP  80 mmHg) the following steps should be attempted:
 Assess for medical causes of hypotension
 Adjust/titrate down any analgesic/sedative/shivering medications. If shivering,
consider neuromuscular blockade
 Observe closely for fluid overload
 Initiate Vasopressors if MAP continues  80 after fluid resuscitation
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Hypertension: For patients on the therapeutic hypothermia protocol who develop
hypertension (MAP > 100 mmHg), consult orders for initiation of NITROglycerin IV.
Electrolyte Replacement
 Have provider evaluate electrolyte replacements if serum creatinine is > 2 mg/dl
 Check STAT potassium and magnesium for any cardiac dysrhythmia and every 4 hours
 After any replacement, check electrolyte level 1 hr after completion of replacement.
 During cooling phase: replace K+ < 3.5
replace Mg++ < 2.0
replace ionized Ca++ < 1.0 or serum Ca++ < 7.5
 Discontinue K replacements 8 hours prior to rewarming
 Discontinue Mg and Ca replacements once warming has begun
Analgesia/Sedation and Shivering
 Use Numeric, Faces or FLACC scale for pain assessments with a goal of less than 3 or
minimal pain behaviors. Refer to orders for analgesia orders.
 Propofol or Dexmedetomidine will be utilized to maintain a RASS (Richmond Agitation –
Sedation Scale) score of -3.
 Buspirone, Acetaminophen, Midazolam, and/or Neuromuscular Blocking Agents (NMBA)
will be administered on an as needed basis to prevent shivering and maintain the BSAS
(Bedside Shivering Assessment Scale) a score of 0.
DVT Prophylaxis
 Utilize antiembolic hose and sequential compression devices
 Administer Enoxaparin unless patient on heparin.
PUD Prophylaxis
 Administer Famotidine as ordered
Blood Product Transfusion
 Blood Warmer is required when cold agglutinins are present (see comments on the
transfusion tag).
Rewarming
The rewarming process should be gradual and take place ideally over 12 or more
hours. For patients with severe bleeding despite measures recommended in the BP
& Volume Management section, a rapid “active rewarming” process should take
place over 8 hours.
 Standard Rewarming Protocol – Cooling Blanket
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1. Monitor for hyperthermia, hypotension and hyperkalemia
2. May discontinue paralytics when temperature is 36 C
3. Consult Neurology services once normothermia (37 C) has been
achieved
4. Once a temperature of 37 C is reached, leave a cooling blanket on top
of the patient with machine set to 37 C for the remainder of the 48hr
period of therapy to avoid rebound hyperthermia
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5. Target is 37 C over approximately 12 hours at a rewarming rate of
0.33 C/hour
6. Manually increase temperature setting on the cooling machine by 1.0
C every 3 hours.
If the patient develops severe bleeding, the patient should be actively
rewarmed according to the following protocol:
 Active Rewarming Protocol – Cooling Blanket
1. Target temperature is 37 C over approximately 8 hours at
0.5 C/hour
2. Manually increase temperature setting on cooling machine by
0.5 C every hour
3. Discontinue paralytics when temperature is 36 C if
appropriate.
Nursing Interventions
 Review Appendix A: Physiologic Effects of Hypothermia
 Accurate weight should be obtained as soon as patient arrives in ICU.
 Infusion therapies, vasopressors and vasodilators may effect heat transfer, increase
potential for skin injury and contribute to adverse hemodynamic response
 The cooling system requires a dedicated rectal temperature probe; correlate with a
secondary temperature probe (foley or CVC) and monitoring of the water temperature
setting on cooling device.
 The heater on the ventilator should be turned off and room temperature should be
lowered to facilitate cooling.
● Assess rectal, foley and water temperature setting every 15 minutes during induction of
hypothermia and rewarming, and every 30 minutes during maintenance.
● All hemodynamic values and signs are recorded hourly
 Arterial line or NIBP is required for BP monitoring
 Place the patient on continuous cardiac monitor
 Lab work: (CBC, Chemistry Panel, Amylase, Lipase, Lactate, Cardiac Enzymes (CK, CKMB, Troponin I) Coagulation profile (PT/INR/PTT), ABG with ionized Ca++. Reassess at
12 and 24 hrs. Potassium and magnesium levels will be monitored every 4 hours.
Consider blood cultures with rewarming. Assess glucose every 4 hours and obtain order
for the IV Insulin Infusion Protocol for BS > 150. (Sub-cu insulin should not be given.)
 Assess baseline LOC and neurological status (Glasgow Coma Scale and TOF, document on
Sedation Flowsheet)
 Assess ventilatory function, because of vasoconstriction, pulse oximetry can be unreliable;
use forehead when possible.
 Assess Continuous ETCO2 monitor to maintain ETCO at 35-45.
 Observe VAP bundle (HOB elevated > 30 degrees, oral care, peptic ulcer disease
prophylaxis, DVT prophylaxis) with exception of sedation weaning and assessment of
readiness to wean until after neurological evaluation when rewarmed
 Assess GI function, abdomen, bowel sounds
 Assess skin integrity. External cooling devices can cause or exacerbate skin injury in
patients without intact skin. Skin check areas covered by cooling blankets every hour.
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 Assess for signs of shivering: palpate masseter, deltoids and pectoralis muscles for
vibration. Observe skeletal muscle movement that may be first detected as ECG artifact.
 Hands, head, and feet should be covered with socks or blankets to help reduce shivering.
 No bathing of patients during therapeutic hypothermia protocol
 Apply antiembolism hose (knee) and sequential compression devices
 Utilize Sport Bed with rotational therapy
 Assess urine output and utilize replacement fluids as ordered
 Utilize hands free defibrillator pads for arrhythmia management
 Do not pull any lines until patient warming is completed.
 No subcutaneous injections (except Lovenox) should be given until patient is rewarmed.
 Report the following to provider:
1. Loss of oxygen saturation signal
2. Inability to reach or maintain target temperature
3. Inability to control shivering
4. Deterioration in coma scale level
5. Loss of bowel sounds
6. ECG changes
7. Cardiac arrhythmias
8. HR < 50 or > 120
9. Urine output < 0.5 ml/kg/hr
Related Policies/Documents:
Pharmacy: Guidelines for Medication Administration via Feeding Tubes
ACM 23: Pain Management
PCS A-7: Application of Antiembolism Stockings
PCS C-5: Use of Pneumatic Compression Sleeve
PCS B-7.1: Blood and Blood Product Transfusion
Neurovascular Flowsheet (Glasgow Coma Scale)
RASS (Richmond Agitation-Sedation Scale)
BSAS (Bedside Shivering Assessment Scale)
IV Insulin Protocol
VAP Bundle
Physiologic Affects of Hypothermia (Appendix A)
Blanketrol II Instructions
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Appendix A. Physiologic Effects of Hypothermia
(Adapted from Burns, S. (2001). Revisiting Hypothermia: A Critical Concept. Critical Care Nurse, 21 (2) 83-86)
Cardiovascular
 Ventricular arrhythmias (hypothermic patients are more susceptible
to atrial and ventricular fibrillation).
 Myocardial depression, bradycardia, angina
 Increased SVR, decreased CO, decreased contractility (hypothermia has a
negative chronotropic effect on pacemaker tissue, which may lead to
bradycardia or AV block).
 Increased PR, QRS, QT intervals
 Hypothermia may cause repolarization abnormalities, producing ST segment
elevation and T-wave inversion.
Respiratory
 Decreased RR (hypoventilation, suppression of cough, and mucociliary
reflexes associated with hypothermia may lead to hypoxemia, atelectasis
and pneumonia.)
 Shift in oxyhemoglobin dissociation curve to the left (less oxygen is released
from oxyhemoglobin to the tissues)
 Decreased cough & increased secretions
Metabolic
 Decreased basal metabolic rate (hypothermia inhibits insulin release from
pancreas, but glucose levels remain normal in mild HT because shivering increases
glucose utilization. Shivering increases metabolic rate, CO2 production, O2
consumption and myocardial work).
 Decreased drug biotransformation
 Decreased tissue perfusion
Gastrointestinal
 Decreased motility, liver function, insulin release
 Ileus
 Stress ulceration
Renal
 Decreased renal plasma flow, Decreased urine output
 Increased specific gravity
 Decreased ADH
Hematologic
 Increased blood viscosity (hemoconcentration)
 Platelet dysfunction
Neurologic
 Confusion
 Coma
 Decreased LOC, decreased reflexes, decreased muscular tone
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Appendix B. Hypothermia Protocol Flow Sheet
INCLUSION CRITERIA






Nontraumatic cardiac arrest with Return of Spontaneous Circulation (ROSC)
Cardiopulmonary Resuscitation (CPR) initiated within 10 minutes of collapse
ROSC within 30 minutes of recognition of the cardiac arrest; MAP ≥ 60 for at least 30
minutes post ROSC with or without vasoactive medication
Initiation of Induced Hypothermia begun within 6 hours of collapse
Initial body temperature must be greater than 30C
No purposeful movement to command and Glascow coma Scale < 6
EXCLUSION CRITERIA









Prolonged arrest time longer than 60 minutes or down time without BLS longer than 10 minutes
Age less than 18 years
Pregnancy
Uncontrolled bleeding, thrombocytopenia or other coagulopathy
DNR or DNI status
Severely impaired pre-arrest cognitive status
Other causes of coma (mass lesions, metabolic coma, seizures, drug overdose, head trauma,
cerebrovascular accident, etc.)
Existing MODS; severe sepsis or comorbidities with minimal chance of meaningful survival
independent of neurological status
Refractory
Yesarrhythmias
No
STOP



Insert Arterial Line
Insert CVC
STEMI: consider TNK / Heparin / PCI / ASA.
Order:










Acetaminophen 650 OGT/NGT/PR Q 6 h
x 24 h, then Q4 h prn temp > 37 C
Buspirone 30 mg OGT/NGT Q 8 h x 24 h
PVD prophylaxis
PUD prophylaxis
Analgesia
Sedation assessment and interventions
Shivering assessment and interventions
Electrolyte replacements
BP and volume management
Lab work

If Temp >34.5 C and no cardiac shock present: infuse 1500 ml of 4C
0.9 NSS over 30 min and repeat 500 ml infusions until core temp <
34.5C or max of 30 ml/kg

If Temp > 34.5C and cardiac shock /LV failure/low EF present: infuse 1500 ml
of 4C 0.9 NSS over 60 min and repeat 500 ml infusions until core temp
< 34.5C or max of 30 ml/kg

Initiate cooling with cooling blanket with target temperature 33 C x 24 hr

Rewarming: After 24 hr. increase temperature 0.33 C every hour

May discontinue NMBA and then wean sedation when patient temp reaches 36C

Maintain patient at 37 C for the remaining 24 hours of therapy
Active Rewarming: Discontinue protocol
and actively rewarm at 0.5 C per hour if
patient develops hemodynamically
unstable arrhythmias; sustained MAP < 60
x 15 min. after resuscitation, severe
bleeding, or awakens.
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