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 Peberdy MA et al. Resuscitation. 2003;58: Kaye W et al. JAMA. 2002:39(5),Suppl A. Cobb L et al. JAMA. 2002;288(23):

Coronary Perfusion and ROSC A well perfused myocardium is more likely to experience return of spontaneous circulation (ROSC)

CPP and ROSC (Paradis et al.) Paradis NA et al. JAMA. 1990;263: Victims with CPP < 15 mmHg do not achieve ROSC With conventional CPR, the overall mean CPP = 12.5

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: centimeters Duty cycle: 50% - 50% Ventilation: 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.) Abella BS et al. JAMA. 2005;293: “…quality of multiple parameters of CPR was inconsistent and often did not meet published guideline recommendations….” Parameter (1 st 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/min60.9%

CPR Challenges: Quality (Abella et al.) Rate too slow Depth too shallow Ventilation rate too high Abella BS et al. JAMA. 2005;293:

CPR Challenges: Quality (Wik et al.) “…chest compressions were not delivered half of the time, and most compressions were too shallow…” Wik L et al. JAMA. 2005; Flow No Flow

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….” Kern KB et al. Circulation. 2002;105: Flow No Flow

Aufderheide TP et al. Circulation. 2004;109: Mean ventilation rate: 30/minute ± 3.2 first group: 37/minute ± 4 after retraining: 22/minute ± 3 16 seconds v v v v v CPR Challenges: Hyperventilation Hyperventilation induces hypotension

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 Bailliere’s Clinical Anaesthesiology. 2000;14(3):

CPR Challenges: Interruptions 77% decrease in ROSC when pre-shock time increased from </= 9.7 seconds to </= 22.5 seconds Edelson et al. Circulation. 2005;112(17)II-1099 Edelson DP, Abella BS et al. Circulation. 2005;112(17):II (Edelson, Abella et al.)

Berg et al, 2001 Blood pressure CPR Challenges: Interruptions (Berg et al.) Time Berg RA et al. Resuscitation. 2001;104: Interrupting chest compressions for rescue breathing can adversely affect hemodynamics during CPR for VF Chest compressions

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

Effective compressions help restore ATP, increasing the likelihood of successful defibrillation CPR Challenges: Defibrillation Support

Compression Depth and Shock Success 50% 60% 88% 100% P<0.01 Edelson et al. Resuscitation 2006 Nov ;71(2):137-45

Hands-Off Interval vs Shock Success 94% 72% 60% 38% 60 consecutive VF arrests at U Chicago Shock success after 1 st DF Edelson et al. Resuscitation 2006 Nov ;71(2):137-45

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

Difficulty of cardiac arrest rhythm identification does not correlate with length of chest compression pause before defibrillation. Crit Care Medicine2006 Dec; 34(12 Suppl):S Abella BS, Kim S, Edelson DP, Huang KN, Merchant RM, Myklebust H, Vanden Hoek TL, Becker LB.

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. Design

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 secs vs. shortest pause quartile of 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. Results

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. Conclusion

Resuscitation volume 77 issue 1 pages ( April 2008 ) Quality of CPR during advanced resuscitation training Gavin D. PerkinsGavin D. Perkins, William Boyle, Hannah Bridgestock, Sarah Davies, Zoe Oliver, Sandra Bradburn, Clare Green, Robin P. Davies, Matthew W. CookeWilliam BoyleHannah Bridgestock Sarah DaviesZoe OliverSandra BradburnClare Green Robin P. DaviesMatthew W. Cooke

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. Design

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. Results

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. Conclusion

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