***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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    ***EXAMPLES*** 
    Input: Background —Interruptions to chest compression – generated blood flow during cardiopulmonary resuscitation ( CPR ) are detrimental . Data show that such interruptions for mouth-to-mouth ventilation require a period of “ rebuilding ” of coronary perfusion pressure to obtain the level achieved before the interruption . Whether such hemodynamic compromise from pausing to ventilate is enough to affect outcome is unknown . Methods and Results —Thirty swine ( weight 35±2 kg ) underwent 3 minutes of untreated ventricular fibrillation before 12 minutes of basic life support CPR .  Animals were r and omized to receive either st and ard airway ( A ) , breathing ( B ) , and compression ( C ) CPR with expired-gas ventilation in a 15:2 compression-to-ventilation ratio or continuous chest compression CPR . Those r and omized to the st and ard 15:2 group had no chest compressions for a period of 16 seconds each time the 2 ventilations were delivered . Defibrillation was attempted at 15 minutes of cardiac arrest . All resuscitated animals were supported in an intensive care environment for 1 hour , then in a maintenance facility for 24 hours . The primary end point of neurologically normal 24-hour survival was significantly better in the experimental group receiving continuous chest compression CPR ( 12 of 15 versus 2 of 15;P < 0.0001 ) . Conclusions —Mouth-to-mouth ventilation performed by single layperson rescuers produces substantial interruptions in chest compression – supported circulation . Continuous chest compression CPR produces greater neurologically normal 24-hour survival  than st and ard ABC CPR when performed in a clinical ly realistic fashion . Any technique that minimizes lengthy interruptions of chest compressions during the first 10 to 15 minutes of basic life support should be given serious consideration in future efforts to improve outcome results from cardiac arrest CONTEXT The survival benefit of well-performed cardiopulmonary resuscitation ( CPR ) is well-documented , but little objective data exist regarding actual CPR quality during cardiac arrest . Recent studies have challenged the notion that CPR is uniformly performed according to established international guidelines . OBJECTIVES To measure multiple parameters of in-hospital CPR quality and to determine compliance with published American Heart Association and international guidelines . DESIGN AND SETTING A prospect i ve observational study of 67 patients who experienced in-hospital cardiac arrest at the University of Chicago Hospitals , Chicago , Ill , between December 11 , 2002 , and April 5 , 2004 . Using a monitor/defibrillator with novel additional sensing capabilities , the parameters of CPR quality including chest compression rate , compression depth , ventilation rate , and the fraction of arrest time without chest compressions ( no-flow fraction ) were recorded . MAIN OUTCOME MEASURE Adherence to American Heart Association and international CPR guidelines . RESULTS Analysis of the first 5 minutes of each resuscitation by 30-second segments revealed that chest compression rates were less than 90/min in 28.1 % of segments . Compression depth was too shallow ( defined as < 38 mm ) for 37.4 % of compressions . Ventilation rates were high , with 60.9 % of segments containing a rate of more than 20/min . Additionally , the mean ( SD ) no-flow fraction was 0.24 ( 0.18 ) . A 10-second pause each minute of arrest would yield a no-flow fraction of 0.17 . A total of 27 patients ( 40.3 % ) achieved return of spontaneous circulation and 7 ( 10.4 % ) were discharged from the hospital . CONCLUSIONS In this study of in-hospital cardiac arrest , the quality of multiple parameters of CPR was inconsistent and often did not meet published guideline recommendations , even when performed by well-trained hospital staff . The importance of high- quality CPR suggests the need for rescuer feedback and monitoring of CPR quality during resuscitation efforts IMPORTANCE A strategy using mechanical chest compressions might improve the poor outcome in out-of-hospital cardiac arrest , but such a strategy has not been tested in large clinical trials . OBJECTIVE To determine whether administering mechanical chest compressions with defibrillation during ongoing compressions ( mechanical CPR ) , compared with manual cardiopulmonary resuscitation ( manual CPR ) , according to guidelines , would improve 4-hour survival . DESIGN , SETTING , AND PARTICIPANTS Multicenter r and omized clinical trial of 2589 patients with out-of-hospital cardiac arrest conducted between January 2008 and February 2013 in 4 Swedish , 1 British , and 1 Dutch ambulance services and their referring hospitals . Duration of follow-up was 6 months . INTERVENTIONS Patients were r and omized to receive either mechanical chest compressions ( LUCAS Chest Compression System , Physio-Control/Jolife AB ) combined with defibrillation during ongoing compressions ( n = 1300 ) or to manual CPR according to guidelines ( n = 1289 ) . MAIN OUTCOMES AND MEASURES Four-hour survival , with secondary end points of survival up to 6 months with good neurological outcome using the Cerebral Performance Category ( CPC ) score . A CPC score of 1 or 2 was classified as a good outcome . RESULTS Four-hour survival was achieved in 307 patients ( 23.6 % ) with mechanical CPR and 305 ( 23.7 % ) with manual CPR ( risk difference , -0.05 % ; 95 % CI , -3.3 % to 3.2 % ; P > .99 ) . Survival with a CPC score of 1 or 2 occurred in 98 ( 7.5 % ) vs 82 ( 6.4 % ) ( risk difference , 1.18 % ; 95 % CI , -0.78 % to 3.1 % ) at intensive care unit discharge , in 108 ( 8.3 % ) vs 100 ( 7.8 % ) ( risk difference , 0.55 % ; 95 % CI , -1.5 % to 2.6 % ) at hospital discharge , in 105 ( 8.1 % ) vs 94 ( 7.3 % ) ( risk difference , 0.78 % ; 95 % CI , -1.3 % to 2.8 % ) at 1 month , and in 110 ( 8.5 % ) vs 98 ( 7.6 % ) ( risk difference , 0.86 % ; 95 % CI , -1.2 % to 3.0 % ) at 6 months with mechanical CPR and manual CPR , respectively . Among patients surviving at 6 months , 99 % in the mechanical CPR group and 94 % in the manual CPR group had CPC scores of 1 or 2 . CONCLUSIONS AND RELEVANCE Among adults with out-of-hospital cardiac arrest , there was no significant difference in 4-hour survival between patients treated with the mechanical CPR algorithm or those treated with guideline -adherent manual CPR . The vast majority of survivors in both groups had good neurological outcomes by 6 months . In clinical practice , mechanical CPR using the presented algorithm did not result in improved effectiveness compared with manual CPR . TRIAL REGISTRATION clinical trials.gov Identifier : NCT00609778 AIM Recently three large post product placement studies , comparing mechanical chest compression ( cc ) devices to those who received manual cc , found equivalent outcome results for both groups . Thus the question arises whether those results could be replicated using the devices on a daily routine . METHODS We prospect ively enrolled 948 patients over a 12 months period . Chi-Square test and Mann-Whitney-U test were used to assess differences between " manual " and " mechanical " cc subgroups . Uni- and multivariate Cox regression hazard analysis were used to assess the influence of cc type on survival . RESULTS A mechanical cc device was used in 30.1 % ( n=283 ) cases . Patients who received mechanical cc had a significantly worse neurological outcome - measured in cerebral performance category ( CPC ) - than the manual cc group ( 56.8 % vs. 78.6 % , p=0.009 ) . Patients receiving mechanical cc  were significantly younger , more were male and were more likely to have byst and er CPR and an initially shock-able ECG rhythm . There was no difference in the quality of CPR that might explain the worse outcome in mechanical cc patients . CONCLUSION Even with high quality CPR in both , manual and mechanical cc groups , outcome in patients who received mechanical cc was significantly worse . The anticipated benefits of a higher compression ratio and a steadier compression depth of a mechanical cc device remain uncertain . In this study selection for mechanical cc was not st and ardized , and was non-r and om . This merits further investigation . Further research on how mechanical cc is chosen and used should be considered . CLINICAL TRIAL REGISTRATION https://ekmeduniwien.at/core/catalog/2013/ ( EK-Nr:1221/2013 ) Background —Recent data highlight a vital link between well-performed cardiopulmonary resuscitation ( CPR ) and survival after cardiac arrest ; however , the quality of CPR as actually performed by trained healthcare providers is largely unknown . We sought to measure in-hospital chest compression rates and to determine compliance with published international guidelines . Methods and Results —We developed and vali date d a h and held recording device to measure chest compression rate as a surrogate for CPR quality . A prospect i ve observational study of adult cardiac arrests was performed at 3 hospitals from April 2002 to October 2003 .  Resuscitations were witnessed by trained observers using a customized personal digital assistant programmed to store the exact time of each chest compression , allowing offline calculation of compression rates at serial time points . In 97 arrests , data from 813 minutes during which chest compressions were delivered were analyzed in 30-second time segments . In 36.9 % of the total number of segments , compression rates were < 80 compressions per minute ( cpm ) , and 21.7 % had rates < 70 cpm . Higher chest compression rates were significantly correlated with initial return of spontaneous circulation ( mean chest compression rates for initial survivors and nonsurvivors , 90±17 and 79±18 cpm , respectively ; P=0.0033 ) . Conclusions —In-hospital chest compression rates were below published resuscitation recommendations , and suboptimal compression rates in our study correlated with poor return of spontaneous circulation . CPR quality is likely a critical determinant of survival after cardiac arrest , suggesting the need for routine measurement , monitoring , and feedback systems during actual resuscitation CONTEXT Defibrillation as soon as possible is st and ard treatment for patients with ventricular fibrillation . A nonr and omized study indicates that after a few minutes of ventricular fibrillation , delaying defibrillation to give cardiopulmonary resuscitation ( CPR ) first might improve the outcome . OBJECTIVE To determine the effects of CPR before defibrillation on outcome in patients with ventricular fibrillation and with response times either up to or longer than 5 minutes . DESIGN , SETTING , AND PATIENTS R and omized trial of 200 patients with out-of-hospital ventricular fibrillation in Oslo , Norway , between June 1998 and May 2001 . Patients received either st and ard care with immediate defibrillation ( n = 96 ) or CPR first with 3 minutes of basic CPR by ambulance personnel prior to defibrillation ( n = 104 ) . If initial defibrillation was unsuccessful , the st and ard group received 1 minute of CPR before additional defibrillation attempts compared with 3 minutes in the CPR first group . MAIN OUTCOME MEASURE Primary end point was survival to hospital discharge . Secondary end points were hospital admission with return of spontaneous circulation ( ROSC ) , 1-year survival , and neurological outcome . A prespecified analysis examined subgroups with response times either up to or longer than 5 minutes . RESULTS In the st and ard group , 14 ( 15 % ) of 96 patients survived to hospital discharge vs 23 ( 22 % ) of 104 in the CPR first group ( P = .17 ) . There were no differences in ROSC rates between the st and ard group ( 56 % [ 58/104 ] ) and the CPR first group ( 46 % [ 44/96 ] ; P = .16 ) ; or in 1-year survival ( 20 % [ 21/104 ] and 15 % [ 14/96 ] , respectively ; P = .30 ) . In subgroup analysis for patients with ambulance response times of either up to 5 minutes or shorter , there were no differences in any outcome variables between the CPR first group ( n = 40 ) and the st and ard group ( n = 41 ) . For patients with response intervals of longer than 5 minutes , more patients achieved ROSC in the CPR first group ( 58 % [ 37/64 ] ) compared with the st and ard group ( 38 % [ 21/55 ] ; odds ratio [ OR ] , 2.22 ; 95 % confidence interval [ CI ] , 1.06 - 4.63 ; P = .04 ) ; survival to hospital discharge ( 22 % [ 14/64 ] vs 4 % [ 2/55 ] ; OR , 7.42 ; 95 % CI , 1.61 - 34.3 ; P = .006 ) ; and 1-year survival ( 20 % [ 13/64 ] vs 4 % [ 2/55 ] ; OR , 6.76 ; 95 % CI , 1.42 - 31.4 ; P = .01 ) . Thirty-three ( 89 % ) of 37 patients who survived to hospital dis 
    Output:
    
However , the results were not statistically significant between different kinds of mechanical chest compression devices and manual resuscitation in survival to admission , discharge and CPC scores for OHCA patients and survival to discharge for in-hospital CA patients .
Conclusions The ability to achieve ROSC with mechanical devise was inferior to manual chest compression during resuscitation .
The use of mechanical chest compression can not be recommended as a replacement for manual CPR , but rather a supplemental treatment in an overall strategy for treating CA patients