Clinical Background on CPR

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• Clinical Background on CPR

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From the weakest link to chain of survival
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The Chain is as strong as the weakest link.
So identifying and strengthening this link is of
utmost importance
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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

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Presenting Rhythms in SCA

• Recent studies show that VF or VT
• is the initial rhythm less than 50 of the time

Peberdy MA et al. Resuscitation.
200358297-308. Kaye W et al. JAMA.
200239(5),Suppl A. Cobb L et al. JAMA.
2002288(23)3008-3013.
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Coronary Perfusion and ROSC
A well perfused myocardium is more likely to
experience return of spontaneous circulation
(ROSC)
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CPP and ROSC (Paradis et al.)

• Victims with CPP lt 15 mmHg do not achieve ROSC
• With conventional CPR, the overall mean CPP 12.5

Paradis NA et al. JAMA. 19902631106-1113.
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AHA/ERC Guidelines 2005 CPR

• Simply put push hard, push fast, allow full
  chest recoil, minimize interruptions in
  compressions

Circulation. 2005112IV-206.
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ERC Guidelines 2005 CPR

• High quality, consistent and uninterrupted chest
  compressions
• Push hard, push fast
• Compression to ventilation ratio 302
• Rate 100 manual compressions per minute
• Depth 4 - 5 centimeters
• Duty cycle 50 - 50
• Ventilation 8 -10 breaths per minute

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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

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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 lt 90/min 28.1
Depth too shallow lt 1.5 in 37.4
Ventilation rate too high gt 20/min 60.9
Abella BS et al. JAMA. 2005293305-310.
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CPR Challenges Quality (Abella et al.)
Rate too slow
Depth too shallow
Ventilation rate too high
Abella BS et al. JAMA. 2005293305-310.
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CPR Challenges Quality (Wik et al.)

• chest compressions were not delivered half of
  the time, and most compressions were too shallow

Flow
No Flow
Wik L et al. JAMA. 200523 299-304.
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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.

Flow
No Flow
Kern KB et al. Circulation. 2002105645-649.
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CPR Challenges Hyperventilation
Hyperventilation induces hypotension
Mean ventilation rate 30/minute 3.2
16 seconds
v v v v v v v v
v v
first group 37/minute 4 after
retraining 22/minute 3
Aufderheide TP et al. Circulation.
20041091960-1965.
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CPR Challenges Perfusion (Kern)
Manual CPR provides minimal blood flow to the
heart and brain
30 - 40 of normal flow
10 - 20 of normal flow
Kern KB Baillieres Clinical Anaesthesiology.
200014(3)591-609.
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CPR Challenges Interruptions
(Edelson, Abella et al.)

• 77 decrease in ROSC when pre-shock time
  increased from lt/ 9.7 seconds to lt/ 22.5 seconds

Edelson et al. Circulation. 2005112(17)II-1099
Edelson DP, Abella BS et al. Circulation.
2005112(17)II-1099.
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CPR Challenges Interruptions (Berg et al.)
Interrupting chest compressions for rescue
breathing can adversely affect hemodynamics
during CPR for VF
Blood pressure
Berg et al, 2001
Time
Chest compressions
Berg RA et al. Resuscitation. 20011042465-2470.
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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).
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CPR Challenges Defibrillation Support
Effective compressions help restore
ATP, increasing the likelihood of successful
defibrillation
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Compression Depth and Shock Success
Edelson et al. Resuscitation 2006 Nov
71(2)137-45
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Hands-Off Interval vs Shock Success

• 60 consecutive VF arrests at U Chicago
• Shock success after 1st DF

Edelson et al. Resuscitation 2006 Nov
71(2)137-45
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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 current-generation automated
  external defibrillators that require long
  pre-shock pauses for rhythm analysis.

Edelson et al. Resuscitation 2006 Nov
71(2)137-45
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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
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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.

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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.

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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.

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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 )
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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.

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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.

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Conclusion

• The implementation of Guidelines 2005 into the
  ALS course appear to have improved the process of
  CPR by reducing no-flow 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.

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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, 305310

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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, 305310
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Resuscitation (2008) 79, 13
DefibrillationSafety versus efficacy
Gavin D. Perkins, Andrew S. Lockey
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In fact, this is what BLS might be