Therapeutic Hypothermia for
Post-Cardiac Arrest Patients
Lois Andrews, RN-BC, MSN, CCRN
10/10

Objectives:
1.
Describe the physiologic effects of hypothermia.
2.
Identify the indications for hypothermia after cardiac arrest.
3.
Identify the contraindications for instituting the hypothermia
protocol.
4.
Describe the process for initiating cooling and rewarming.
Historical Perspective
Hypothermia Defined
hypothermia = 32-35◦C
 Moderate = 28- 32◦C
 Severe = 20-28◦C
 Mild
2005 Recommendation
AHA & ILCOR
Recommended inducing & maintaining for
12 to 24 hours, Therapeutic hypothermia
(33°C) after ROSC in patients
experiencing OHCA who remain comatose
hours of after resuscitation & in whom the
initial cardiac rhythm is VF.
2010 International Consensus
Therapeutic hypothermia: Adult patients who are
comatose (not responding in a meaningful way
to verbal commands) with spontaneous
circulation after out-of-hospital VF cardiac arrest
should be cooled to 32–34°C for 12–24 h.
Induced hypothermia might also benefit comatose
adult patients with spontaneous circulation after
OHCA from a non-shockable rhythm or inhospital cardiac arrest.
Pathophysiology of
Post-Cardiac Arrest
Brain ischemia during cardiac arrest
(Global vs Focal)
Inflammation and injury
Increased ICP
Poor neurological outcome
Physiologic Effects of
Hypothermia
 Desired




effects:
Decreases the cerebral
metabolic rate (1°C = 5-7%)
Inhibits influx of Ca &
glutamate accumulation
Suppresses ischemiainduced inflammatory
cytokines
Reduces disruptions in BBB
& vascular permeability
Physiologic Effects of
Hypothermia

Potential adverse effects:
 Decreases heart rate
 Decreases phosphate and
potassium concentrations
 Decreases gut motility
 Increases blood glucose concentrations
 Increases systemic vascular resistance
 Prolongs clotting times
 May cause diuresis
 May decrease the number and function
of WBCs and platelets
Hypothermia Protocol
IS THE PATIENT A CANDIDATE
FOR THERAPEUTIC
HYPOTHERMIA?
Inclusion Criteria for Therapeutic
Hypothermia

Cardiac arrest patient, post resuscitation with
return of spontaneous circulation and persistent
coma (GCS < 6)

Resuscitation time (time of collapse to return of
spontaneous circulation) should be < 1 hour

Patient is intubated

Time from resuscitation to initiation of hypothermia
< 6 hours (ideally, but up to 12)
Exclusion Criteria for Therapeutic
Hypothermia
 Absolute:
(If the patient meets any of the
below, he/she is not a candidate)






DNR code status
Metastatic cancer or other terminal illness
Responds to verbal commands
Pregnancy
Comatose baseline due to CNS depressing
drugs or other possible cause
Temperature < 30ºC (86ºF)
Relative Exclusion Criteria: (the physician may continue to
order the Hypothermia Protocol based on the belief that the
benefits outweigh the potential risk)










Hemodynamic instability (MAP < 60mmHg) for more than 30
minutes post resuscitation
Uncontrolled cardiac arrhythmias, multiple arrests/ pulseless
periods
Prolonged QT interval (> 0.45)
Prolonged hypoxemia (SaO2 < 85%) for greater than 15
minutes after return of spontaneous circulation
Delay of greater than 15 minutes to initiation of BLS
Patients with known bleeding diathesis or with active ongoing
bleeding
Platelet count < 50,000/mL
Recent surgery (within 14 days)
Active sepsis
Etiology of cardiac arrest thought to be caused by trauma or
severe bleeding
Background Information
To be successful, the patient must be
managed in three phases:
 Cooling
 Maintenance
 Rewarming
LET’S GET STARTED!

Physician completes inclusion & exclusion criteria on page 1 of
orders

As soon as decision is made to start hypothermia, begin
sedation. NO SEDATION VACATION DURING COOLING
PHASE.

Induction of hypothermia should begin as soon as possible after
ROSC and can be quickly achieved with 30mL/kg or 2L of cold
(4°C) IV fluid and packing the patient’s neck, axilla & groin with
ice packs. (AHA 2010)
LIFEFLIGHT OF MAINE: CRITICAL CARE TRANSPORT TEAM
3.2a NEUROPROTECTIVE INDUCED HYPOTHERMIA AFTER CARDIAC
ARREST
Procedure:
A. Institute cooling as early as possible. Temp goal is 33°C.
B. Sedate and paralyze the patient as per Protocol 2.3.; Veccuronium is
preferred. Suppress shivering with neuromuscular blockade.
C. Rapid IV infusion of ice cold (4°C). LR. Administer 30 ml/kg IVx1 dose over a
period of 30 minutes immediately after neuromuscular blocking agent
administered. Maximum of 2 liters LR during transport.
D. Apply ice packs to patient’s neck, axilla, and inguinal area after patient is
sedated and paralyzed and iced LR is administered IV.
E. If patient shivering increase sedative and/or analgesia dose prior to increasing
paralytic
F. Monitor temperature via esophageal temperature probe –as time and mission
allow.
G. Consider turning on aircraft AC to assist with cooling enroute.
H. Report to receiving tertiary care center.
In the ICU

Prior to initiation of cooling:

Have initial labs drawn

Perform a thorough skin assessment

Place temperature probe: PA, Foley or esophageal & rectal



Turn room thermostat to lowest setting during cooling and maintenance
phase
Prepare for A-line and CVP line insertion.
Ventilator circuit – no heating
In the ICU

Patients will be on the following protocols:
 Electrolyte replacements
 Glycemic Control/Intensive insulin
 Neuromuscular blockade
 Correct potassium (goal of 3.5) PRIOR to onset of
cooling therapy
 Admitting MD to consult critical care intensivist (if
applicable) to manage therapeutic hypothermia
LAB and DIAGNOSTIC STUDIES
 Stat Portable Chest x-ray on admission
 Stat 12-lead EKG on admission
 Labs on admission: Complete Metabolic Panel, iCa, LFTs, amylase,
lipase, CBC w/diff, PT/PTT/INR
 Labs every 4hrs x 24hrs: Basic Metabolic Panel, magnesium,
phosphorus, CBC w/diff, PT/PTT/INR

Obtain one set of blood cultures 12 hours after onset of cooling
(Hypothermia may mask infection)

During warming – BMP q 4 hrs
COOLING PHASE




Cool patient to a target temperature of 32º - 34º C (89.6º
- 93.2º F) within 6-12 hours of onset of arrest. Maintain
at target temperature for 24 hours.
Monitor and record VS, CVP, cardiac rhythm and
primary temperature q 30 min. until goal temp is
achieved.
Correlate and record secondary temperature source q
2hours.
If unable to achieve target core temperature, consult MD
COOLING PHASE
Shivering

Perform shivering assessment hourly throughout
cooling phase (Palpate mandible to assess for shivering)

If shivering occurs during cooling phase, implement
Critical Care Neuromuscular Blocker orders.

Preferred Neuromuscular blocking agents are
Cisatracurium, Atracurium, or Vecuronium. (NO
neuromuscular drug holiday during the cooling
phase!)
 PATIENT
SHOULD REMAIN AT
TARGET TEMPERATURE FOR 24
HOURS.
MAINTENANCE PHASE




Once target temp is achieved, monitor and record VS,
CVP, cardiac rhythm and primary temperature hourly
and PRN during maintenance.
Correlate and record secondary temperature every 2
hours
Assess skin every 2 hours for any signs of breakdown
If patient has recurring malignant dysrhythmias
discontinue cooling, begin rewarming and notify MD.
REWARMING PHASE
Active vs Passive








Should begin 24 hours after target temperature achieved
Proceed with rewarming slowly (0.5° - 1° C per hour) over 6-8 hours
to prevent vasodilation, hypotension and rapid fluid & electrolyte
shifts.
Draw BMP q 4 hrs, but DO NOT replace potassium during
rewarming phase (shifts back into serum from cells)
Discontinue neuromuscular blockers once patient’s temperature
>36ºC, but continue sedation until TOF = 4.
If shivering occurs, apply warm blankets or use Demerol
Do not permit hyperthermia in the first 24 hours after cooling.
Administer acetominophen for temp >37ºC (98.6ºF)
Once normothermic goal reached for 48 hours, consult MD for
removal of unnecessary lines.
SNGH TH Patients
12
10
8
Total
Completed
Expired
SNF
Home
6
4
2
0
2008
2009
2010
CONCLUSION

Cardiac arrest with widespread
cerebral ischemia frequently leads to
severe neurologic impairment. Induced
hypothermia is a promising method that
increases the rate of favorable neurologic
outcome and reduces mortality.