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Science Behind the Guidelines

ECC. Science Behind the Guidelines. John M. Field M.D. FAHA, FACC, FACEP Professor Medicine & Surgery PSU College Medicine Penn State Heart and Vascular Institute Senior Science Editor Emergency Cardiovascular Care Programs AHA National Center, Dallas.

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Science Behind the Guidelines

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  1. ECC Science Behind the Guidelines John M. Field M.D. FAHA, FACC, FACEP Professor Medicine & Surgery PSU College Medicine Penn State Heart and Vascular Institute Senior Science Editor Emergency Cardiovascular Care Programs AHA National Center, Dallas

  2. The Importance of Early Defibrillation …the perceived value of antiarrhythmics, vasopressors, advanced airway control and ventilation has declined markedly since 1992- the evidence is disappointingly weak that any of these interventions convey effective benefit to cardiac arrest patients. CURRENTS AHA September, 2000

  3. The Importance of Early Defibrillation …the relative value of early defibrillation by reducing 1-2 minutes the interval between adult sudden cardiac arrest and a first defibrillatory shock does more to improve survival than the benefit from medications, airway interventions and newly designed defibrillation waveforms combined. CURRENTS AHA September, 2000

  4.                  First Response with AED %  100 75 50 0 AED Survival Rates for Out-of-Hospital VF 40 35 30 25 20 15 10 5 0  1975 1977 1979 1981 1983 1985 1987 1989 1991 19993 Cobb, L. A. et al. JAMA 1999;281:1182-1188.

  5. 1.6 4.4 BLS 3.7 3.4 1.1 Survival to Hospital Discharge Variable Adjusted Odds Ration Age < 75yrs First Link- Early Access Second Link- Bystander CPR Third Link- Early Defib Fourth Link- ACLS Stiell, I. G. et al. N Engl J Med 2004;351:647-656

  6. G U I D E L I N E S 2 0 0 5 • Guidelines 2005 • Major changes • Science Behind The Guidelines • Major Challenges 1

  7. G U I D E L I N E S 2 0 0 5 • Guidelines 2005 • SUMMARY • Major changes • Science Behind The Guidelines 1

  8. G U I D E L I N E S 2 0 0 5 Weighing the Evidence Grade of Evidence • Data from many large, randomized trials • Data from fewer, smaller randomized trials, careful analyses of nonrandomized studies, observational registries • Expert consensus

  9. ECC Weighing the Evidence Data from clinical trials, significant Rx effects Data from clinical trials, smaller Rx effects Prospective non-randomized cohort studies Historic or case controlled studies Case series- no control group Animal or model studies Extrapolation Common sense or common practice LEVEL 1 LEVEL 8

  10. I IIa IIb III Class of Recommendations Intervention is useful and effective Evidence conflicts/opinions differ but leans towards efficacy Evidence conflicts/opinions differ but leans against efficacy Intervention is not useful/effective and may be harmful

  11. ECC Class of Recommendations I IIa IIb III I Intervention is useful and effective Evidence conflicts/opinions differ but leans towards efficacy Evidence conflicts/opinions differ but leans against efficacy Intervention is not useful/effective and may be harmful No evidence of benefit-not harmful

  12. ECC G U I D E L I N E S 2 0 0 5 Atropine (Asystole/PEA) 1mg IV Q 3-5 minutes (total dose-3mg) • No prospective studies support use • LOE – 3, 4, 5, 6 • Class Recommendation- Indeterminate

  13. G U I D E L I N E S 2 0 0 5 Major Recommendations • Emphasis  effective chest compressions • Ventilations delivered over one second • Single compression-ventilation ratio • Single shock followed by immediate CPR •  Emphasis advanced airway • Recommendation intraosseous access (IO)  Emphasis ET drug administration

  14. G U I D E L I N E S 2 0 0 5 Key Emphasis • Performance of High Quality CPR • Integration of CPR-BLS and ACLS • Chest Compressions • Early Defibrillation

  15. G U I D E L I N E S 2 0 0 5 Major Recommendation Effective chest compressions

  16. CPR SYSTOLE (compression) CPR DIASTOLE (relaxation) Coronary Perfusion Pressure (Ao diastolic - RA diastolic)

  17. Survival- Prolonged CPR 35 30 25 20 Paradis CPP, mm Hg 15 10 5 0 24 hr Surv ROSC-EXP NO ROSC Berg RA et al: Circulation 2001;104:2465-70

  18. G U I D E L I N E S 2 0 0 5 ROSC NR • Push hard and push fast 100 COMPRESSION, MIN-1 Compression Rate vs ROSC 80 60 40 20 QUARTILE Yu Circulation 2002;106:368

  19. ROSC Chest Compression RateIn-Hospital CPR Abella Circulation 2005:111

  20. Rescue Breaths What really happens- 20 16 14 Seconds for 2 breaths 12 10 0 Lay Med Std Medics Ewy et al: Circulation 2005;111:2134-42

  21. Lay persons: 2 rescue breaths interrupted CC for 16 seconds Actual CC/min=39±11 Assar, 2000 16 secs 58% 42%

  22. Myocardial Blood Flow and CPP after 16 seconds of interrupting CPR 22 Continuous 100 Continuous 20 90 P<0.001 P<0.001 18 80 MBF, ml/100g/min CPP, mm Hg 16 15:2 70 14 15:2 60 12 10 50 Berg RA et al: Circulation 2001;104:2465-70 ICCM, WT, 10/04

  23. Probability - Successful Defibrillation Interruption Chest Compression 50 n=156 45 40 35 PROSC, % 30 25 20 15 10 5 0 5 10 15 20 Duration of hands-off, seconds Eftestol T et al: Circulation 2002;105:2270-3

  24. Intrathoracic Pressure Incomplete Chest Recoil Mm Hg % Decompression Yannopoulos Resuscitation 64:363

  25. Incomplete Relaxation Aufderheide Resuscitation 2005 64:353-62

  26. Rescuer Fatigue Compressions/ minute 30% - COULD NOT COMPLETE Minute of Resuscitation Ashton Resuscitation 2002

  27. Effective Chest Compressions • Push hard and push fast • Limit Interruptions • Allow full chest recoil • Switch every 2 minutes 1

  28. Death by Hyperventilation RATE/ min mmHg/min mmHg % Aufderheide TP Circulation 2004; 109:1960-5

  29. G U I D E L I N E S 2 0 0 5 Major Recommendations Deliver ventilations over one second  Avoid Hyperventilation-Too fast Too much

  30. G U I D E L I N E S 2 0 0 5 Major Recommendations Single Compression:Ventilation Ratio Except- HCP 2 rescuer CPR for infants and children 30:2

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