***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND The rate of survival after out-of-hospital cardiac arrest is low . It is not known whether this rate will increase if laypersons are trained to attempt defibrillation with the use of automated external defibrillators ( AEDs ) . METHODS We conducted a prospect i ve , community-based , multicenter clinical trial in which we r and omly assigned community units ( e.g. , shopping malls and apartment complexes ) to a structured and monitored emergency-response system involving lay volunteers trained in cardiopulmonary resuscitation ( CPR ) alone or in CPR and the use of AEDs . The primary outcome was survival to hospital discharge . RESULTS More than 19,000 volunteer responders from 993 community units in 24 North American regions participated . The two study groups had similar unit and volunteer characteristics . Patients with treated out-of-hospital cardiac arrest in the two groups were similar in age ( mean , 69.8 years ) , proportion of men ( 67 percent ) , rate of cardiac arrest in a public location ( 70 percent ) , and rate of witnessed cardiac arrest ( 72 percent ) . No inappropriate shocks were delivered . There were more survivors to hospital discharge in the units assigned to have volunteers trained in CPR plus the use of AEDs ( 30 survivors among 128 arrests ) than there were in the units assigned to have volunteers trained only in CPR ( 15 among 107 ; P=0.03 ; relative risk , 2.0 ; 95 percent confidence interval , 1.07 to 3.77 ) ; there were only 2 survivors in residential complexes . Functional status at hospital discharge did not differ between the two groups . CONCLUSIONS Training and equipping volunteers to attempt early defibrillation within a structured response system can increase the number of survivors to hospital discharge after out-of-hospital cardiac arrest in public locations . Trained laypersons can use AEDs safely and effectively BACKGROUND Sudden death from cardiac causes remains a leading cause of death among patients with congestive heart failure ( CHF ) . Treatment with amiodarone or an implantable cardioverter-defibrillator ( ICD ) has been proposed to improve the prognosis in such patients . METHODS We r and omly assigned 2521 patients with New York Heart Association ( NYHA ) class II or III CHF and a left ventricular ejection fraction ( LVEF ) of 35 percent or less to conventional therapy for CHF plus placebo ( 847 patients ) , conventional therapy plus amiodarone ( 845 patients ) , or conventional therapy plus a conservatively programmed , shock-only , single-lead ICD ( 829 patients ) . Placebo and amiodarone were administered in a double-blind fashion . The primary end point was death from any cause . RESULTS The median LVEF in patients was 25 percent ; 70 percent were in NYHA class II , and 30 percent were in class III CHF . The cause of CHF was ischemic in 52 percent and nonischemic in 48 percent . The median follow-up was 45.5 months . There were 244 deaths ( 29 percent ) in the placebo group , 240 ( 28 percent ) in the amiodarone group , and 182 ( 22 percent ) in the ICD group . As compared with placebo , amiodarone was associated with a similar risk of death ( hazard ratio , 1.06 ; 97.5 percent confidence interval , 0.86 to 1.30 ; P=0.53 ) and ICD therapy was associated with a decreased risk of death of 23 percent ( 0.77 ; 97.5 percent confidence interval , 0.62 to 0.96 ; P=0.007 ) and an absolute decrease in mortality of 7.2 percentage points after five years in the overall population . Results did not vary according to either ischemic or nonischemic causes of CHF , but they did vary according to the NYHA class . CONCLUSIONS In patients with NYHA class II or III CHF and LVEF of 35 percent or less , amiodarone has no favorable effect on survival , whereas single-lead , shock-only ICD therapy reduces overall mortality by 23 percent STUDY OBJECTIVES This study was conducted to identify modifiable factors associated with survival for prehospital cardiac arrest in a large , multicenter EMS system with basic life support/defibrillation ( BLS-D ) level of care . METHODS This observational cohort study constitutes Phase I of the 3-phase Ontario Prehospital Advanced Life Support ( OPALS ) Study . Included were all adults who had cardiac arrest before EMS arrival in 21 urban/suburban communities that operate under the jurisdiction of 1 ambulance services branch , have 911 telephone service , and provide ambulance defibrillation but no prehospital advanced life support ( ALS ) . Central dispatch and ambulance records were review ed according to the Utstein guidelines . Associations between multiple patient and EMS factors and survival to discharge were assessed by univariate then stepwise logistic regression analyses . RESULTS From January 1 , 1991 , to January 31 , 1995 , 5,335 eligible patients were treated . Of these , 46.8 % of cardiac arrests were witnessed by citizens , 14.5 % received byst and er CPR , 25.6 % received CPR by fire or police , and 38.2 % had an initial rhythm of ventricular fibrillation/ventricular tachycardia ( VF/VT ) . The mean interval from call received to vehicle stopped was 6.7 minutes . Survival was 3.5 % overall and 8.8 % for VF/VT . Multivariate analysis found the following factors to be independently associated with survival ( odds ratio with 95 % confidence intervals ) : age.81 ( . 73,.89 ) , byst and er-witnessed arrest 4.05 ( 2.78 , 5.90 ) , byst and er CPR 2.98 ( 2.07 , 4.29 ) , CPR by fire or police 2.20 ( 1.46 , 3.31 ) , and response interval call received to vehicle stopped.76 ( .71,.82 ) . CONCLUSION This represents the largest multicenter BLS-D study of prehospital cardiac arrest yet conducted and clearly indicates that patient survival may be improved by optimization of EMS response intervals , byst and er CPR , as well as first-responder CPR by fire or police CONTEXT Survival rates for out-of-hospital cardiac arrest are low ; published survival rates in Ontario are only 2.5 % . This study represents phase II of the Ontario Prehospital Advanced Life Support ( OPALS ) study , which is design ed to systematic ally evaluate the effectiveness and efficiency of various prehospital interventions for patients with cardiac arrest , trauma , and critical illnesses . OBJECTIVE To assess the impact on out-of-hospital cardiac arrest survival of the implementation of a rapid defibrillation program in a large multicenter emergency medical services ( EMS ) system with existing basic life support and defibrillation ( BLS-D ) level of care . DESIGN Controlled clinical trial comparing survival for 36 months before ( phase I ) and 12 months after ( phase II ) system optimization . SETTING Nineteen urban and suburban Ontario communities ( population s ranging from 16 000 to 750 000 [ total , 2.7 million ] ) . PATIENTS All patients who had out-of-hospital cardiac arrest in the study communities for whom resuscitation was attempted by emergency responders . INTERVENTIONS Study communities optimized their EMS systems to achieve the target response interval from when a call was received until a vehicle stopped with a defibrillator of 8 minutes or less for 90 % of cardiac arrest cases . Working both locally and provincially , communities implemented multiple measures , including defibrillation by firefighters , base paging , tiered response agreements with fire departments , continuous quality improvement for response intervals , and province-wide revision and implementation of st and ard dispatch policies . All response times were obtained from a central dispatch system . MAIN OUTCOME MEASURE Survival to hospital discharge . RESULTS The 4690 cardiac arrest patients studied in phase I and the 1641 in phase II were similar for all clinical and demographic characteristics , including age , sex , witnessed status , rhythm , and receipt of byst and er cardiopulmonary resuscitation . The proportion of cases meeting the 8-minute response criterion improved ( 76.7 % vs 92.5 % ; P<.001 ) as did most median response intervals . Overall survival to hospital discharge for all rhythm groups combined improved from 3.9 % to 5.2 % ( P = .03 ) . The 33 % relative increase in survival represents an additional 21 lives saved each year in the study communities ( approximately 1 life per 120000 residents ) . The charges were estimated to be US $ 46900 per life saved for establishing the rapid defibrillation program and US $ 2400 per life saved annually for maintaining the program . CONCLUSION An inexpensive , multifaceted system optimization approach to rapid defibrillation can lead to significant improvements in survival after cardiac arrest in a large BLS-D EMS system STUDY OBJECTIVE Many centers optimize their emergency medical services ( EMS ) systems to achieve a target defibrillation response interval of " call received by dispatch " to " arrival at scene by responder with defibrillator " in 8 minutes or less for at least 90 % of cardiac arrest cases . The objective of this study was to analyze survival as a function of time to test the evidence for this st and ard . METHODS This prospect i ve cohort study included all adult , cardiac etiology , out-of-hospital cardiac arrest cases from phases I and II of the Ontario Prehospital Advanced Life Support ( OPALS ) study . Patients in the 21 Ontario study communities received a basic life support level of care with defibrillation by ambulance and firefighters but no advanced life support .  Survival was plotted as a function of the defibrillation response interval . The equation of the curve , generated by means of logistic regression , was used to estimate survival at various defibrillation response interval cutoff points . RESULTS From January 1 , 1991 , to December 31 , 1997 , there were 392 ( 4.2 % ) survivors overall among the 9,273 patients treated . The defibrillation response interval mean was 6.2 minutes , and the 90th percentile was 9.3 minutes . There was a steep decrease in the first 5 minutes of the survival curve , beyond which the slope gradually leveled off . Controlling for known covariates , the decrement in the odds of survival with increasing response interval was 0.77 per minute ( 95 % confidence interval 0.74 to 0.83 ) . The survival function predicts , for successive 90th percentile cutoff points , both survival rates and additional lives saved per year in the OPALS communities compared with the 8-minute st and ard : 9 minutes ( 4.6 % ; -18 lives ) , 8 minutes ( 5.9 % ; 0 lives ) , 7 minutes ( 7.5 % ; 23 lives ) , 6 minutes ( 9.5 % ; 51 lives ) , and 5 minutes ( 12.0 % ; 86 lives ) . CONCLUSION The 8-minute target established in many communities is not supported by our data as the optimal EMS defibrillation response interval for cardiac arrest . EMS system leaders should consider the effect of decreasing the 90th percentile defibrillation response interval to less than 8 minutes The Ontario Prehospital Advanced Life Support Study represents the largest prehospital study yet conducted , worldwide . This study will involve more than 25,000 cardiac arrest , trauma , and critically ill patients over an 8-year period . The study will evaluate the incremental benefit of rapid defibrillation and prehospital Advanced Cardiac Life Support measures for cardiac arrest survival and the benefit of  Advanced Life Support  for patients with traumatic injuries and other critically ill prehospital patients . This article describes the OPALS study with regard to the rationale and methodology for cardiac arrest patients The Philips HeartStart Home Defibrillator is an automated external defibrillator ( AED ) that is approved for home use by untrained users . Most cardiac arrests occur in the home , so a rapid response with cardiopulmonary resuscitation ( CPR ) and defibrillation is critical for survival . No prospect i ve studies demonstrate that the use of AEDs in the home by untrained persons improves health outcomes . Further investigation is needed to determine the benefit and harm of AEDs in the home 
    Output:
    
Thus , AEDs can be used by first responders to deliver early defibrillation in out-of-hospital and hospital setting s. However , simply providing an AED would not likely improve survival outcomes .
There is little doubt regarding the effectiveness and safety of AEDs to treat people in cardiac arrest .
Thus , in an out-of-hospital setting , general use of AEDs by laypersons would not be cost-effective .
Nevertheless , the PAD study found that when response time was fixed , the application of AED improved survival .
The results suggested that deployment of AEDs in hospitals would be cost-effective in terms of cost per quality adjusted life year gained .
Conversely , deployment of AEDs in office buildings , apartments , and houses was not cost-effective .
CONCLUSIONS The OPALS study model appears cost-effective , and effectiveness can be further enhanced by training community volunteers to improve the byst and er-initiated CPR rates .
Deployment of AEDs in all public access areas and in houses and apartments is not cost-effective .