Table 4. Trends in Bystander CPR and AED Use.

Rates of both bystander CPR and lay person deployment of AEDs increased during the study period.

	2005-2006	2007	2008	2009	2010	2011	2012	P for trend
Person performing CPR								<0.001
Bystander	28.2%	33.1%	33.8%	31.6%	31.8%	36.7%	36.3%
First responder	35.1%	32.1%	35.0%	36.4%	38.1%	26.5%	29.3%
EMS personnel	36.7%	34.8%	31.2%	32.0%	30.1%	36.8%	34.4%
Bystander AED use*
All Arrests	1.9% (18/946)	2.3% (49/2173)	3.7% (138/3686)	3.5% (210/6021)	3.6% (298/8270)	4.5% (493/10,853)	4.2% (692/16,614)	<0.001
Witnessed arrests	6.5% (14/217)	5.6% (27/481)	9.2% (78/847)	9.1% (122/1340)	10.3% (183/1784)	9.5% (259/2719)	9.4% (398/4224)	0.048

Abbreviation: AED, automated external defibrillator; CPR, cardiopulmonary resuscitation; EMS, emergency medical services

^*By convention, for calculations of bystander AED use, we excluded from consideration patients with a witnessed arrest for whom CPR was initiated by a first responder (police, firemen) or EMS personnel, as bystanders would not be expected to deploy an AED in these circumstances