10/27/2009
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Nathan Ruch, MD FACEP Why hypothermia?
How does it work?
h h l ? Who can we help?
What is the pre‐hospital experience?
Unknown ECG tracings.
74yo male with funny feeling in his chest while shopping for shoes
Prior CABG Prior CABG
Medications are metoprolol and aspirin
Patient is a retired pharmacist
25 with suffer cardiac arrest during this talk
About 1000 Americans today
h h lf k h h l Less than half make it to the hospital
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Cardiac arrest Greater than 90% mortality rate
No significant decline over past few decades despite g p pnew drugs and improved access to electrical defibrillation
Return of spontaneous circulation (ROSC) Many patients go on to die during subsequent hospitalization
Neurologic impairment often remains as a lasting morbidity
450,000 sudden deaths per year in the US
<10% discharged from the hospital
h h l Many who “survive” have poor neurologic outcome
First reported 50 years ago
Decreased core temp reduces metabolic demand
b d d d d Abandoned due to resource requirements and lack of proven benefit
49 year old with pain in right arm that began while spreading mulch
No past medical history No past medical history
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Mild Hypothermia
90‐95F (32‐35C)
Moderate H pothermia Moderate Hypothermia
82‐89F (28‐32C)
Severe Hypothemia
<82 (<28C)
Nobody really knows
Reduced basal cellular energy requirements
d d f d l d Reduced free radical production
Improved cell membrane stability
Improved immune function
Decreased cytokine production
73yo woman with palpitations
Some left chest pain and dizziness
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77 patients
43 Hypoothermia
34 Normothermia 34 Normothermia
Results
49% good outcome with hypothermia
26% good outcome with normothermia
AHA – 2005 Guidelines
ILCOR – 2002 Consensus statement
Unconscious adults with ROSC after out of hospital cardiac arrest should be cooled to 32‐34C for 12‐24 hours when the initial rhythm is VF34C for 12 24 hours when the initial rhythm is VF
Such cooling may be useful for other rhythms and in hospital cardiac arrest
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Yes 13%
No 87%
Duration on non‐perfusing rhythm
Bystander CPR
l d f b ll Early defibrillation –AED’s
Quality of CPR
Age
Therapeutic hypothermia
One out of 5 hospital deaths is sudden cardiac arrest.
Overall survival in US is 5 8% Overall survival in US is 5‐8%
Good neurologic outcome in 3% of out of hospital arrests.
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Surface cooling (cooling blankets/ice bags)
Endovascular catheters
C l fl d Cool IV fluids
Cardiopulmonary bypass
Cooling caps/helmets
Rectal
Esophageal
Tympanic
Oral
PA catheter
Bladder
Axilla
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Unintentional overcooling <32C
Coagulopathy
l h h Ventricular arrhythmias
Increased risk of infection
Below 30C defibrillation may not be effective
Optimal duration unknown
12‐24 hours
Sh Shivering
Active rewarming 1C/HR
Heating blanket
Warm IV fluids
May help overcome institutional inertia
May aid in directing post arrest patient to most capable hospitalscapable hospitals
Pre‐hospital protocols mitigate hospital delays
Improves outcome
Requires minimal equipment and training
82yo woman who slipped and struck her head while reaching for a pot in the kitchen
Triage heart rate of 58 Triage heart rate of 58
Patient denies syncope or other symptoms
ECG done by tech with no order from MD
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www.wakeems.com/saem
Wake County/Raleigh, NC:
Single, 3rd service EMS System with 65,000 calls/year
Reliable firefighter first response Reliable firefighter first response
Resident population of ~825,000 (add 100 per day)
Post‐resuscitation patients are selectively transported to one of 2 high volume PCI centers
All calls receive EMD from a single, high‐volume center
Fire first response with AED and compressions Fire first response with AED and compressions
Paramedic response with transport ambulances
Supervisory response at paramedic level
Baseline [Jan 2004‐Apr 2005]: Traditional CPR, focus on airway
New CPR [Apr 2005‐Apr 2006]: Continuous New CPR [Apr 2005 Apr 2006]: Continuous compressions, delayed intubation for VF/VT
Impedance Threshold Device (ITD) [Apr 2006‐Oct 2006]
Induced Hypothermia [Oct 2006‐Oct 2007]
ROSC after cardiac arrest not related to trauma or hemorrhage
Age 16 years or greater Age 16 years or greater
Female without obviously gravid uterus
Initial temperature >34 C
Patient is intubated (no RSI)
Patient remains comatose without purposeful response to pain
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All EMS records are maintained in an electronic database
Records with any of the following characteristics Records with any of the following characteristics are reviewed to determine if cardiac arrest occurred:
EMS Patient Disposition = cardiac arrest
CPR procedure is recorded
Defibrillation is recorded
Age less than 16
Obvious traumatic origin of arrest
S d EMS witnessed arrest
Arrest not in EMS control
Prison facilities
Out‐of‐system intercept
Arrests under direction of non‐EMS physician
Data were analyzed using logistic regression
Covariates offered for the regression:
A Age
Gender
Response time for the first defibrillator
Witnessed status
Location
Primary outcome was the proportion of OOH‐CA patients for whom resuscitation was attempted that survived to discharge in baseline vs. hypothermia g ypphases
Secondary outcomes include (by phase):
Pulse at emergency department, survival to admission, neurological intact survival to discharge
Additionally, results were stratified by initial rhythm
3124 OOH‐CA occurred during the study period 1442 obvious deaths (no resuscitation attempted) 1682 attempted resuscitations 484 of 1682 were excluded due to: 119 not under EMS control/not a code 109 obvious traumatic origin 70 under the age of 16 206 EMS witnessed
1198 met inclusion criteria
Total OOH-CA N= 1198
Baseline N = 372
New CPR N= 319New CPR N= 319
ITD N= 148
Hypothermia N= 359
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Mean Age 65
Percent male 58%
Private Residence 81%
Witnessed Status 36%
Bystander CPR 36%
Mean Defibrillator Response
5.3 – 6.1 mins
Initially VF/VT 26%
NOTE: no statistically significant difference between study periods
10
12
14
16
7.3%
8.2%
11.6%
P<0.05*
0
2
4
6
8
Baseline New CPR ITD Hypo
4.6%
* when compared with baseline
20
25
30
35
40
Percent survival 12%
22%
29%
37%
P<0.05*
0
5
10
15survival
Baseline New CPR ITD Hypo
Treatment Period
12%
* When compared with baseline
4
5
6
7
8
Neuro4 4%
6.2%
7.8%
P <0.05*
0
1
2
3
4Intact
Baseline New CPR ITD Hypo
Treatment Period
1.9%
4.4%
* When compared with baseline
20
25
30
35
Neuro 20%
28%
P<0.05 *
0
5
10
15
eu oIntact
Baseline New CPR ITD Hypo
Treatment Period
10%
17%
20%
* When compared with baseline
25
30
35
**
0
5
10
15
20
Pulse @ ED Admit D/C Neuro
Baseline
Hypo
* P <0.05 when compared with baseline
**
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Confounders
Removal of stacked defibrillations
Protocol driven pre and post resuscitation cardiac Protocol‐driven pre‐ and post‐resuscitation cardiac arrest care
Improvement with procedures due to repetition
Hawthorne effect
Intention‐to‐treat analysis
Induced hypothermia is not experimental therapy
Part of standard therapy post arrest (IIb/Ilb)
Few complications
Not expensive
Time sensitive
Impacts outcome (NNT 8)
14 yo girl with palpitations
Takes verapamil 240mg
S l d h Similar episodes in the past
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