An evaluation of the Public Access Defibrillation (PAD) Demonstration

3.1 The evidence for PAD

Page last updated: August 2008

3.1.1 Findings from the 2004 review
3.1.2 Update: evidence published since 2004

3.1.1 Findings from the 2004 review

The 2004 Jacobs review identified a number of sources of evidence for the effectiveness of PAD in increasing survival rates for people who suffer cardiac arrest in public places. Studies cited came to the following conclusions.
  • A study of a PAD program in American airports concluded that 21 persons had suffered an arrest during the two-year project period, of which 62% were successfully resuscitated using an AED.

  • An Italian study compared the use of PAD to traditional EMS treatment for cardiac arrest, a higher survival rate was shown for people treated by volunteers trained to use AEDs compared with EMS services.

  • Only one sizeable randomised control trial was reported (the studies described above were non-controlled observational studies). This American study randomised sites into two groups: one set of sites was provided with CPR training alone (control group), the other with CPR training and training in the use of AEDs (intervention group). The study demonstrated a higher (almost double) survival rate for the intervention group compared with the control group.
However, the 2004 review was quick to point out that the object of these studies was not Public Access Defibrillation in its truest sense. The programs in question were generally based on a 'first responder' that centred on trained personnel operating the device, rather than the lay public.

Based on these considerations, the 2004 review concluded that:

The evidence to date supports the premise that early defibrillation delivered within a PAD mode improves survival following cardiac arrest occurring outside of hospital (Jacobs 2004, p.14).

3.1.2 Update: evidence published since 2004

In 2004 (shortly after the submission of the original literature review to the Department), Culley et al. published a cohort study of the impact of a PAD program on cardiac survival rates in Seattle and Washington, America (Culley 2004). The study compared survival rates for out-of-hospital cardiac arrests for those treated with an AED vs. those treated with traditional EMS. Culley concluded that PAD was involved in a small proportion of successful resuscitations for out-of-hospital cardiac arrests. The proportion of successful cardiac arrests was noted to increase over time as the implementation of the program progressed. Compared with traditional EMS, Culley concludes:

Survival rate was 50% in cases treated by PAD AED, a figure considerably better than most EMS systems (p. 1861)
A literature review by Clare (2006)15 also concluded that there was some evidence for the efficacy of PAD programs. Following the examination of 22 studies of PAD and related programs, the review concluded that PAD programs had a small but noticeable improvement in survival rates for people who suffered sudden cardiac arrest in public places. However, the paper noted that many of the studies in question incorporated bystander Cardiopulmonary Resuscitation (CPR) training as part of their interventions. The presence of people with CPR training was reported to exert a far greater effect over survival rate compared with PAD alone. The paper concluded:

Finally the effect of level one PAD programmes is partially dependent on the provision of bystander CPR (CPR by a member of the public with no duty to respond) as physiologically CPR maintains the shockable cardiac arrest rhythm by perfusing the heart and preventing degradation into asystole (p. 1061).

15 Conducted separately from the 2004 review for the Department