Automatic External Defibrillation

1. Automatic External Defibrillation Aaron J. Katz, AEMT-P, CIC www.es26medic.net Revised for 2005 AHA Protocols

2. AHA Chain of Survival • Early access • Early CPR • Early defibrillation • Early ALS

3. Cardiac electrophysiology • SA Node • “dominant pacemaker” • “Fires” 60-100 times per minute • Internodal pathways • AV Node • Bundle of HIS • Left and right bundle branches • Purkinje network

5. Nonperfusing heart rhythms • Ventricular tachycardia (“VTACH”) • Ventricular fibrillation (“VFIB”) • Asystole • Electromechanical dissociation (EMD) • Pulseless electrical activity (PEA)

6. VTACH

7. VFIB

8. Asystole

9. The bottom line • All the above abnormal heart rhythms can not produce a perfusing pulse • Pulseless VTACH and VFIB CAN be successfully converted to a perfusing rhythm using a defibrillator

10. AED – the technology • Very accurate computer enabling recognition of lethal rhythms (“Analyze”) • Modern AED will talk • Shocking mechanism (“Shock”) • Automatic vs. semiautomatic

11. Common AED errors • Bad battery • Patient moving • AED applied to a responsive patient

12. Bad battery • Use fully charged batteries • Depends on manufacturer • Pay attention to AED warnings about batteries • Bad batteries are uncommon today • COLD WEATHER

13. Patient moving • Causes inaccurate analysis • Don’t touch the patient • Stop the bus when analyzing!

14. AED applied to a responsive patient • AED applied to a responsive patient with a rapid pulse • AED may falsely interpret as VTACH – and recommend shock • Therefore: only apply AED to an unresponsive pulseless patient

15. Complications & solutions • Patient has a pacemaker • Apply pads 1” from pacemaker • AICD • No danger to EMT! • Small amount of energy • Apply pads 1” from pacemaker • Very hairy chest • Shave the area • Keep a disposable razor with your defibrillator

16. Integrating AED into CPR

17. AED integration • Arrive at the scene • Assess responsiveness • Stop CPR (EMTs or bystanders) • Verify pulselessness & apnea • EMS Witnessed Arrest? • Perform CPR until defibrillator is attached • Arrest not witnessed by EMS? • Two minutes of CPR prior to using defibrillator

18. AED integration – cont’d • Prepare for defibrillation: • Bare the chest • Remove nitro paste/patches • Apply pads to the chest • Look at the pads, they show you how • Right: right of sternum under clavicle • Left: left ribs • Top of pad should 2-3” below armpit • Apply them smoothly • STOP CPR

19. AED integration – cont’d • Shout “clear” 3 times • “I’m clear, you’re clear, everybody clear” • Analyze • AED may tell you “analyzing – do not touch the patient” • Results…

20. AED integration – cont’d • Analysis at any time will result in either: • Shock advised • AED will charge and tell you to clear the patient and press shock • No shock advised • Patient may have a pulse • Patient has a nonshockable rhythm • Asystole, EMD/PEA

21. Shocks recommended • One Shock • Check pulse… • Two minutes of CPR • Press Analyze • Shock if recommended • Two minutes of CPR • …

22. Continue • After 3 cycles of CPR or if spontaneous breathing occurs, begin transport • During transport, continue CPR, re-analyze every 2 minutes, and shock as indicated

23. No shock advised • No spontaneous breathing? • 2 minutes of CPR • Analyze/Shock as indicated/2 minutes of CPR cycles • Spontaneous breathing • Assess vital signs • Support airway • Support breathing • Transport