Clinical Background
on CPR
From the weakest link to chain of survival
The Chain is as strong as the weakest link….
So identifying and strengthening this link is of
utmost importance
Circulation is Critical for Survival
• Provides oxygen to preserve vital organ function
• Converts non-shockable rhythms (asystole,
PEA) to shockable ones (VF, VT)
– More than half of all arrests involve non-shockable
rhythms
Presenting Rhythms in SCA
Recent studies show that VF or VT
is the initial rhythm less than 50% of the time
120%
% of Cardiac Arrests
100%
80%
59%
60%
75%
40%
41%
20%
25%
0%
Hospital
EMS
VF/VT
Peberdy MA et al. Resuscitation. 2003;58:297-308.
Kaye W et al. JAMA. 2002:39(5),Suppl A.
Cobb L et al. JAMA. 2002;288(23):3008-3013.
PEA/Asystole
Coronary Perfusion and ROSC
A well perfused myocardium is more likely to experience
return of spontaneous circulation (ROSC)
CPP and ROSC (Paradis et al.)
Victims with CPP < 15 mmHg do not achieve ROSC
With conventional CPR, the overall mean CPP = 12.5
90%
79%
% of patients w/ ROSC
80%
70%
60%
46%
50%
40%
30%
20%
10%
0%
0%
<15
15-25
CPP (mm Hg)
Paradis NA et al. JAMA. 1990;263:1106-1113.
>25
AHA/ERC Guidelines 2005: CPR
“Simply put: …push hard, push fast,
allow full chest recoil, minimize
interruptions in compressions…”
Circulation. 2005;112:IV-206.
ERC Guidelines 2005: CPR
• High quality, consistent and uninterrupted
chest compressions
• Push hard, push fast
• Compression to ventilation ratio: 30:2
• Rate: 100 manual compressions per minute
• Depth: 4 - 5 centimeters
• Duty cycle: 50% - 50%
• Ventilation: 8 -10 breaths per minute
CPR Challenges
• Poor quality
– Inconsistent rate, depth, duty cycle
• Harmful interruptions
– Required due to clinician fatigue, patient transport
• Inadequate cerebral and coronary perfusion
• Ineffective defibrillation support
CPR Challenges: Quality (Abella et al.)
• “…quality of multiple parameters of CPR was
inconsistent and often did not meet published
guideline recommendations….”
Parameter (1st 5 minutes)
Criteria
% of Time Incorrect
Rate too slow
< 90/min
28.1%
Depth too shallow
< 1.5 in
37.4%
Ventilation rate too high
> 20/min
60.9%
Abella BS et al. JAMA. 2005;293:305-310.
Parameter (1st 5 minutes)
CPR Challenges: Quality (Abella et al.)
Rate too slow 28.1%
Depth too shallow 37.4%
Ventilation rate too high
0%
60.9%
10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
% of Time Incorrect
Abella BS et al. JAMA. 2005;293:305-310.
CPR Challenges: Quality (Wik et al.)
“…chest compressions
were not delivered half
of the time, and most
compressions were too
shallow…”
No Flow
52%
48%
% time no CC
Flow
48%
% too shallow
% too deep
33%
0%
% incomplete release
25%
0%
Wik L et al. JAMA. 2005;23 299-304.
20%
40%
60%
CPR Challenges: Interruptions (Kern et al.)
“…Any technique that minimizes lengthy interruptions of chest
compressions during the first 10 to 15 minutes of basic life support
should be given serious consideration in future efforts to improve
outcome results from cardiac arrest….”
38%
Flow
62%
No Flow
Kern KB et al. Circulation. 2002;105:645-649.
CPR Challenges: Hyperventilation
Hyperventilation induces hypotension
Mean ventilation rate: 30/minute ± 3.2
16 seconds
v
v
v
v
first group: 37/minute ± 4
Aufderheide TP et al. Circulation. 2004;109:1960-1965.
v
v
v
v
v
v
after retraining: 22/minute ± 3
CPR Challenges: Perfusion (Kern)
Manual CPR provides minimal blood flow
to the heart and brain
10% - 20% of normal flow
30% - 40% of normal flow
Kern KB Bailliere’s Clinical Anaesthesiology. 2000;14(3):591-609.
CPR Challenges: Interruptions
(Edelson,
Abella et al.)
77% decrease in ROSC when pre-shock time increased
from </= 9.7 seconds to </= 22.5 seconds
100%
90%
87%
80%
70%
ROSC
60%
50%
40%
30%
20%
20%
10%
0%
</= 9.7 sec
Edelson et al. Circulation. 2005;112(17)II-1099
Edelson DP, Abella BS et al. Circulation. 2005;112(17):II-1099.
</= 22.5 sec
CPR Challenges: Interruptions (Berg et al.)
Blood pressure
Interrupting chest compressions for rescue breathing can
adversely affect hemodynamics during CPR for VF
Berg et al, 2001
Chest compressions
Berg RA et al. Resuscitation. 2001;104:2465-2470.
Time
CPR Challenges: Defibrillation Support
After ~4 minutes of VF, the myocardium is nearly depleted of
ATP*, a vital energy source needed for successful defibrillation
*Adenosine triphosphate (ATP), which breaks down into adenosine diphosphate (ADP).
Myocardial Cell
100% ATP
Myocardial Cell
<10% ATP
Myocardial Cell
30-40% ATP
CPR Challenges: Defibrillation Support
Effective compressions help restore ATP,
increasing the likelihood of successful defibrillation
Compression Depth and Shock Success
100%
80%
P<0.01
P<0.01
88%
100%
60%
Shock
Success 40%
50%
60%
20%
0%
<26 mm
26-38 mm
39-50 mm
Compession Depth (mm)
Edelson et al. Resuscitation 2006 Nov ;71(2):137-45
>50 mm
Hands-Off Interval vs Shock Success
•
60 consecutive VF arrests at U Chicago
•
Shock success after 1st DF
100%
80%
94%
72%
60%
Shock
Success 40%
60%
38%
20%
0%
<10
10-20
21-30
Hands-Off Interval (sec)
Edelson et al. Resuscitation 2006 Nov ;71(2):137-45
>30
Conclusions
The quality of CPR prior to defibrillation directly affects
clinical outcomes. Specifically, longer pre-shock
pauses and shallow chest compressions are
associated with defibrillation failure. Strategies to
correct these deficiencies should be developed and
consideration should be made to replacing currentgeneration automated external defibrillators that
require long pre-shock pauses for rhythm analysis.
Edelson et al. Resuscitation 2006 Nov ;71(2):137-45
Abella BS, Kim S, Edelson DP, Huang KN, Merchant RM,
Myklebust H, Vanden Hoek TL, Becker LB.
Difficulty of cardiac arrest rhythm identification
does not correlate with length of chest
compression pause before defibrillation.
Crit Care Medicine2006 Dec; 34(12 Suppl):S427-31
Design
•
Prospective in-hospital study of cardiac arrest
resuscitation attempts coupled with a retrospective
review of preshock pause rhythms by 12 trained
providers. Reviewers scored rhythms by ease of
identification using a discrete Likert scale from 1 (most
difficult to identify) to 5 (easiest to identify). The
resuscitation cohort was organized into preshock
pause-duration quartiles for statistical analysis.
Resident physicians were then surveyed regarding
human factors affecting preshock pauses.
Results
•
A total of 118 preshock pauses from 45 resuscitation
episodes were collected. When evaluated by quartiles
of preshock pause duration, difficulty of rhythm
identification did not correlate with increasing pause
time.
•
In fact, the opposite was found (longest preshock
pause quartile of 23.8-60.2 secs vs. shortest pause
quartile of 1.1-7.9 secs; rhythm difficulty scores, 3.2 vs.
3.0; p = .20).
•
When 29 resident physicians who recently served on
resuscitation teams were surveyed, 18 of 29 (62.1%)
attributed long pauses to lack of time sense during
resuscitation, and 16 of 29 (55.2%) thought that room
crowding prevented rapid defibrillation.
Conclusion
•
Long cardiopulmonary resuscitation pauses
before defibrillation are likely due to human
factors during the resuscitation and not due to
inherent difficulties with rhythm identification.
This preliminary work highlights the need for
more research and training in the area of
team performance and human factors during
resuscitation.
Gavin D. Perkins, William Boyle, Hannah Bridgestock,
Sarah Davies, Zoe Oliver, Sandra Bradburn, Clare Green,
Robin P. Davies, Matthew W. Cooke
Quality of CPR during advanced resuscitation training
Resuscitation volume 77 issue 1 pages 69-74 ( April 2008 )
Design
•
Observational study of quality of CPR during
advanced life support training courses before
and after the implementation of the European
Resuscitation Council Guidelines 2005 into
the ALS course. The quality of chest
compressions were downloaded from a
manikin and direct observations of no-flow
time; pre-shock pauses were recorded.
Results
•
•
•
•
•
94 cardiac arrest simulations were studied (46 before
implementation of Guidelines 2005 and 48 after).
Delays in starting CPR, inadequate compression depth,
prolonged interruptions of chest compressions and
excessive pre-shock pauses were identified.
The introduction of Guidelines 2005 resulted in
improvements in the number of compressions given per
minute and a reduction in no-flow time and duration of
pre-shock pauses
overall the quality of CPR performed during the ALS
course remained poor.
There was little evidence of performance improving
over successive simulations as the course progressed.
Conclusion
•
The implementation of Guidelines 2005 into the ALS course
appear to have improved the process of CPR by reducing noflow time during simulated CPR. However, the quality of CPR
during ALS training remains sub-optimal. Delays in starting
CPR, inadequate compression depth, excessive interruptions
in chest compressions and prolonged pre-shock pauses mirror
observations from clinical practice. Strategies to improve CPR
performance during ALS training should be explored and
potentially may result in improvements in clinical practice.
Current handposition
•The
current approach to chest compressions
In 80% of the 189 patients’ CT images, the intrathoracic
structure just underneath the INL was the ascending aorta
(18.0%), the root of aorta (48.7%), or the left ventricular
outflow tract (12.7%), rather than the left ventricle itself
Jungho, Joong and Kyuse, Resuscitation (2007) 75, 305—310
Current handposition
For more efficient and effective chest compression
during CPR, compressing the sternum more caudally
than the INL should be considered if it is not associated
with the risk of increasing internal visceral
injuries
Jungho, Joong and Kyuse, Resuscitation (2007) 75, 305—310
Resuscitation (2008) 79, 1—3
Defibrillation—–Safety versus efficacy
Gavin D. Perkins, Andrew S. Lockey
In fact, this is what BLS might be