EMS Controversies in Prehospital Care

1. EMSControversies in Prehospital Care Aric Storck PGY1 Dr. Andy Anton June 26, 2003

2. Objectives • Public Access Defibrillation • Better or worse than targeted first responder programs? • Defibrillation +/- CPR • Shock first or CPR first? • Prehospital Triage • Is it accurate and is it safe?

3. Background • Cardiovascular disease is a major cause of death in North America • 1 million deaths per year in US • ~450,000 sudden and unexpected • Most occur outside of hospital • Poor survival rates (1-5% in some major centres)

4. The target of PAD Incidence of Unexpected Cardiac Arrest (NEJM 2002:347(16);1223-1224)

5. Very, very good evidence that survival is intimately linked to • CPR • Timeliness of defibrillation

6. NEJM 2002:347(16);1223-1224

7. Public Access Defibrillation • What is it? • PAD is a strategy to improve survival from VF arrest by placing AED’s in the hands of trained (and untrained) laypersons • What is the rationale? • Survival decreases by 7-10% for every passing minute of VF. PAD allows for earlier defibrillation.

8. What is an Automatic External Defibrillator? JAMA 2001 285(9)1193

9. Circulation 1999;100(16):1703-1707 Sequence of AED voice prompts during mock cardiac arrest.

10. JAMA 2001;285(9):1196 Electrocardiograms From a Person in Cardiac Arrest

11. What about EMS and AED’s? • Many studies (which will not be reviewed here) show AED’s to be an effective part of EMS • Some studies suggest AEDs more effective than manual defibrillators among paramedics • Many studies have shown increased survival with targeted first responders (police, firefighters, etc.) carrying AEDs

12. AEDs Outside the Traditional EMS System • Some (including AED manufacturers …) have argued for a “fire extinguisher” model • AEDs widely located in public and private places to achieve defibrillation ASAP

13. Public Access Defibrillation • VF is the most frequent initial rhythm in witnessed cardiac arrest • Electrical defibrillation is the most effective treatment of VF • Probability of successful defibrillation diminishes rapidly over time • VF tends to converts to asystole after a few minutes

14. Time to Defibrillation vs Rates of Survival to Hospital Discharge Rates given for 4 years of consecutive patients (1112) initially discovered in ventricular fibrillation. Response times are known for 942 cases. Both witnessed and unwitnessed cases in this 4-year period are considered. The average (SD) response time for first emergency unit was 3.0 (1.5) minutes and for paramedics was 6.5 (3.2) minutes after dispatch. VF indicates ventricular fibrillation. JAMA 2001;285(9):1196

15. Expected Survival According to the Interval between Collapse and the Administration of the First Shock by the Defibrillator. NEJM 2002;347(16):1223-1224

16. So What Does the Literature Say…

17. Outcomes of Rapid Defibrillation by Security Officers After Cardiac Arrest in CasinosValenzuela T, et al. NEJM. 2000;343(17):1206-1209. • Casinos are unique environments amenable to a rapid defibrillation program • Security officer visible from every point at all times • Security cameras closely monitor public areas • Many elderly patrons in poor health

18. Methods • Prospective study • Prospective target of 100 VF arrests • 32 participating casinos in Nevada, Pennsylvania, and Mississippi • AEDs placed at intervals to ensure <3 minute elapsed time between collapse and defibrillation

19. Training • Security officers required to have basic CPR • 6 hour course in AED use • Theoretical and practical training • 75% required on exam to pass

20. Subjects • Inclusion • Unconscious • Unresponsive • No palpable pulse • No spontaneous respiration • Exclusion • <9 years old • <36 kg

21. Protocol • When informed of “sick person” the nearest officer procedes to the patient • Begins CPR if needed • Second officer brings nearest AED to patient • AED immediately attached and prompts followed • Resuscitation continued until EMS arrival or return of spontaneous circulation and respiration

22. Data Colection • Time of collapse obtained from security cameras or interview with witness (if not in a public area) • AED recorded • Rhythm strip for analysis • Time of shocks

23. Outcome Variables • Predictor variables • Time from collapse to CPR • Time from collapse to defibrillation • Primary outcome variable • Survival to hospital discharge

24. Results • Total Cardiac Arrests - N = 148 • Initial rhythm VF = 105 • Initial rhythm PEA = 17 • Initial rhythm asystole = 26 • NB: No subjects without VF as initial rhythm survived

25. Ventricular Fibrillation • 105/148 arrests (71%) • 15/105 unobserved collapse • 3/15 (20%) survival to discharge • 4/105 pronounced dead on scene • 35/105 pronounced dead at hospital ER • 10/105 admitted to hospital but died before d/c • 56/105 (53%) survived to hospital discharge

26. Witnessed VF Arrests • 90/105 VF arrests • 54% received CPR prior to arrival of AED • Collapse to CPR 2.9+/-2.8 minutes • Collapse to defibrillation 4.4 +/- 2.9 • Collapse to arrival of EMS 9.8+/-4.3 • Survival to hospital discharge 53 (59%)

27. Valenzuela, et al. NEJM 2000

28. The importance of time … • Defibrillation < 3 minutes after witnessed arrest • Survival 74% (26/35) • Defibrillation > 3minutes after witnessed arrest • Survival 49% (27/55) • P=0.02

29. Implications • Rapid AED use by targeted responders is an effective and feasible strategy • Much improved survival compared with previous estimates of out of hospital arrest survival • Minimally trained personnel (ie. security officers) can safely and effectively operate AEDs • Waiting for paramedics would have added ~5 minutes to time to defibrillation

30. Limitations • Casinos are atypical environments • Very intense monitoring • Very high density of cardiac arrests • Survival very dependent on collapse to defibrillation interval • Must be able to ensure very rapid response times

31. Use of AEDs by a U.S. AirlinePage R, et al. NEJM. 2000;343:1210-6. • Aircraft are unique settings for cardiac arrest • Stress/exertion associated with flying • Disruption of circadian rhythms • Decreased oxygen tension in cabin • VF arrests on airplanes rarely survive due to the delay obtaining EMS and defibrillation • Minimum 20 minutes required for emergency landing under the best of circumstances

32. Methods • In 1997 American Airlines began installing AEDs on all aircraft • All 24,000 flight attendants were trained in AED use • One hour classroom • Four hour workshop • 1.5 hour refresher courses • Use of AEDs monitored for a 2 year period

33. AED Protocol • When SSx of possible cardiac arrest • Patient moved to aisle, galley, bulkhead • Clothing covering chest is removed • Electrodes placed on chest • Assistance of medical personnel is solicited • Flight attendants follow instructions on AED

34. Results • Patient characteristics • N=200 • 66% male • Mean age 58 years • 191 aboard aircraft • 9 in terminals

35. Indications for AED use • LOC - 99 (49.5%) • Chest Pain – 62 patients • Dyspnea 19 • Nausea / malaise – 8 • Light-headedness – 3 • Palpitations – 3 • Stroke – 1 • Unclear reasons – 5 • NB – physician assisted with 139 patients (69.5%)

36. Electrocardiographic Data • 185 electrocardiograms available for review • 15 lost due to device malfunction, memory erased, etc • 145 – sinus rhythm • 14 sinus bradycardia • 21 sinus tachycardia • 8 – atrial fibrillation • 3 – junctional rhythm • SVT – 1 • MAT -1

37. Agonal rhythm – 13 • Ventricular fibrillation - 14

38. Shocks and survival • 13/14 patients with documented VF defibrillated • defibrillation withheld at request of one patient’s family • 13/13 – VF terminated with first shock • Recurrent VF in 8 patients • 7/8 successfully resuscitated with subsequent shocks • NB – two patients defibrillated for presumed VF but data lost in machine. Both patients died

39. Outcomes • 6/15 (40%) patients defibrillated were discharged home from hospital with full neurologic recovery

40. Use of defibrillator as a monitor • Used and recorded ECG on 171 patients without VF • 101/200 patients did not have LOC • In no case was a shock inappropriately administered • Specificity for algorithm = 100%

41. No shocks recommended or delivered inappropriately • Sensitivity 100% • Specificity 100% Page R, et al. NEJM 2000;343:1210-6.

42. Frequency of defibrillator use • 200 uses on • 627,956 flights • 896,000,000 miles • 70,801,874 passengers • AED used once per 3288 flights • Death or resuscitation once per 21,654 flights

43. Conclusions • AEDs 100% sensitive and 100% specific • VF terminated after first shock 100% of time • Rate of survival to discharge 40% • AEDs safe for use as monitor • Allows further assessment of need to divert aircraft or utilize medications in the emergency medical kit

44. What about Real Public Access Defibrillation?

45. Public Use of Automatic External DefibrillatorsCaffrey S, et al. NEJM. 2002;347(16):1242-1247. • AEDs shown to save lives when used by designated personnel in certain public places • Prospective study to determine whether random bystanders could successfully retrieve and use AEDs for cardiac arrest

46. Methods • AEDs placed at 60-90 second intervals in three Chicago area airports (100 million passengers per year) • Use of AEDs promoted in media, pamphlets, and videos in waiting areas • Outcomes • Time from notification of dispatchers to defibrillation • Survival at 72 hours and one year • Neurologic status • Characteristics of rescuers

47. Study design • Study sites • O’Hare – 80,000,000 passengers/year • 59 AED’s • Midway – 20,000,000 passengers/year • 10 AED’s • Meigs field – 77,000 passengers/year • 1 AED

48. CPR/AED training provided to 450 employees • Airport police • Security • Public safety dispatchers • Voluntary training of 3,000 / 40,000 other airport employees

49. AEDs • Housed in glass cabinet 60-90sec apart • Highly visible signs indicating location of nearest AED • Cabinets equipped with alarms / dispatcher alerts

50. Data collected • Dispatch time • Defibrillation time • Recovery time (return of consciousness) • ECG tracing • Audio recording