Transcript Document

SCD and Therapeutic
Hypothermia
Ruchika Husa, MD
OSU Wexner Medical Center
Clinical Vignette
• Young female found down by coworker
in the UCSD temporary office building.
• No bystander CPR upon code teams
arrival.
• pulseless, non-responsive.
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Intubation
Shock 1
Shock 2
Shock 3
Shock 4
Shock 5
Shock 6
00:45
02:45
05:30
08:30
10:30
11:45
ROSC
Post Resuscitation
• Cooled. Full neurologic recovery.
• No baseline ECG abnormalities.
• Cardiac MRI without anatomic
abnormalities.
• ICD and discharge after 12 days.
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Objectives
• Evidence behind therapeutic
hypothermia
• Patient selection
• Methods of cooling
• Timing of cooling
• Degree of hypothermia
• Duration of hypothermia
Why should we cool?
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Reperfusion Injury
Reperfusion
Ischemia
0
10
20
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Why should we cool?
• Reperfusion injury
• Necrosis/apoptosis
• Inflammation
• Reactive oxygen species
• Improved defibrillation
• B-blocker effect?
Historic perspective
• Open heart surgeries: moderate
hypothermia (28C to 32C) used since the
1950s to protect the brain during intra-op
global ischemia.
• Successful use of hypothermia after SCD
described in 1950s but subsequently
abandoned due to lack of evidence.
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Cont.
• Guideline 2000 for CPR and Emergency
Cardiovascular care did not include
therapeutic hypothermia after arrest.
• In 2002 the results of 2 prospective
randomized trials lead to addition of this
recommendation to the guidelines.
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Why should we cool?
• Entry criteria: witnessed cardiac
arrest with first resuscitation attempt
5-15 min after collapse, ROSC (<60
from collapse), persistent coma, VF.
• Exclusion criteria: severe
cardiogenic shock, hypotension
(SBP <90mmHg), persistent
arrhythmias, primary coagulopathy.
• Approximately 92% of screened
participants were excluded.
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PROTOCOL
• In European study, patients were
cooled using a special mattress and
ice packs. Target temp 32℃ to 34℃ for
24 hours. Rewarming over 8 hours.
• Australian study used cold packs in
the field. Target temp 33℃ for 12 hours.
Rewarming over 6 hours.
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Why should we cool?
Hypothermia After Cardiac Arrest Study Group (2002) NEJM
NEUROLOGIC OUTCOME AND MORTALITY AT SIX
MONTHS
OUTCOME
NORMOTHERMIA
HYPOTHERMIA
RISK RATIO (95% CI)* P VALUE†
no./total no. (%)
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Favorable neurologic
54/137 (39)
75/136 (55)
1.40 (1.08–1.81)
0.009
outcome
•
Death
6/138 (55)
56/137 (41)
0.74 (0.58–0.95)
0.02
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ALS Task Force
recommendation in 2002
• Unconscious adult patients with spontaneous
circulation after out-of-hospital cardiac arrest
should be cooled to 32℃ to 34℃ for 12-24
hours when initial rhythm was ventricular
fibrillation.
• Such cooling may be beneficial for other
rhythms or in-hospital cardiac arrest.
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Why should we cool?
Post-Arrest Care
• Cooling
• Emergency PCI
• Good ICU care
• Rehab?
Post-Arrest Care
Sunde (2007) Resuscitation
Prognostic factors affecting
survival with favorable outcomes
Prognostic factors
Adjusted odds ratio
Intervention period
Age >70
Time to ROSC
Ambulance response time
Initial VF
95% CI
4.47
1.60—12.52
0.48
0.17—1.37
0.91
0.85—0.96
0.91
0.78—1.07
1.84
0.33—10.41
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Post-Arrest Care
Prehospital Cooling Issues
• Does post-arrest cooling in the field
really make that much difference?
• Should we be cooling during arrest?
• Does cooling distract from other
tasks?
• Are there patients with complications
from cooling that cannot be identified
in the field?
When should we cool?
• Cellular approach
• Pre-treatment
• Necrosis/apoptosis
• Inflammation/ROS
• Pragmatic approach
• Intra-arrest
• Prehospital ROSC
• ED
• ICU
When should we cool?
Necrosis
Apoptosis
0
1
2
3
4
5
6
7
Days
8
9
10
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12
13
14
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When should we cool?
Hypothermia After Cardiac Arrest Study Group (2002) NEJM
When should we cool?
Abella (2004) Circulation
When should we cool?
Kuboyama (1993) Crit Care Med
When should we cool?
Nozari (2006) Circulation
When should we cool?
Nozari (2006) Circulation
Prehospital Hypothermia
Prehospital Hypothermia
Kim (2007) Circulation
Prehospital Hypothermia
Kim (2007) Circulation
Who should we cool?
• All arrest victims?
• Brain doesn’t know the rhythm
• Only ventricular fibrillation?
• Evidence-based approach
• Non-VF patients?
• Infection
• CHF
• Bleeding
Resuscitation - September 2011
Mild therapeutic hypothermia is associated with
favourable outcome in patients after cardiac arrest with
non-shockable rhythms
- Retrospective analysis of adult cardiac arrest survivors suffering a witnessed
out-of-hospital cardiac arrest with asystole or pulseless electric activity as the first
documented rhythm.
- Patients who were treated with mild therapeutic hypothermia were more likely to
have good neurological outcomes, odds ratio of 1.84 (95% confidence interval:
1.08–3.13).
- Mortality was significantly lower in the hypothermia group (odds ratio: 0.56; 95%
confidence interval: 0.34–0.93).
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Resuscitation - February 2012
Does therapeutic hypothermia benefit adult cardiac
arrest patients presenting with non-shockable initial
rhythms?: A systematic review and meta-analysis of
randomized and non-randomized studies.
•
TH is associated with reduced in-hospital mortality for adults patients
resuscitated from non-shockable CA.
•
However, most of the studies had substantial risks of bias and quality
of evidence was very low.
•
Further high quality randomized clinical trials would confirm the actual
benefit of TH in this population.
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Recent trial
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Trial design
• Randomized 950 unconscious adults after out-ofhospital cardiac arrest of presumed cardiac cause
(irrespective of initial rhythm) to targeted
temperature management at either 33°C or 36°C.
• The primary outcome was all-cause mortality
through the end of the trial.
• Secondary outcomes included a composite of poor
neurologic function or death at 180 days
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Body Temperature during the Intervention Period.
Nielsen N et al. N Engl J Med 2013;369:2197-2206.
Probability of Survival through the End of the Trial.
Nielsen N et al. N Engl J Med 2013;369:2197-2206.
Results
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Complications of Hypothermia
• Coagulopathy
• Overshoot?
• Hemodynamic
• Dysrhythmias
• Infectious
• Sepsis, pneumonia
• Electrolyte disturbances
Who should we cool?
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How should we cool?
• Surface cooling
• Evaporative
• Ice packs/chemical
• Cooling pads
• Internal strategies
• Cooled intravenous fluids
• Intravascular catheters
• Intranasal catheters
Cooling Catheters
Surface Cooling
How cold?
• Official recommendations
• Target temp 32-34o C
• ? 36◦C
• Threshold for effect?
• Adverse effects?
• Really cold?
• Different mechanisms
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Deep Hypothermia
20 min
Circulatory
Arrest
Deep Hypothermia
How long?
• Official recommendations
• Inflammatory pattern
• Peak at 72 hours
• Customized
• Depth and duration
How long?
Assessing neurologic recovery
• New thoughts on longer waiting time
prior to withdrawal of care.
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Suggested protocol
• OOHCA with ROSC
• Iced saline in EMS or ED
• Cooling catheter  surface cooling with
pads
• Median time from ED arrival to initiation
of hypothermia < 30min
• Bladder temp probe
• Avoid shivering
• Aggressively control hyperthermia
(fever) post rewarming.
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Parting Thoughts
• More patients should be closely
monitored for hyperthermia
• The complications of hypothermia
should be anticipated, not avoided
• Future research may help clarify the
optimal “dose” and duration of
hypothermia