***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: 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 Objective : To compare cardiopulmonary resuscitation ( CPR ) with a compression to ventilation ( C : V ) ratio of 15:2 vs. 30:2 , with and without use of an impedance threshold device ( ITD ) . Design : Prospect i ve r and omized animal and manikin study . Setting : Animal laboratory and emergency medical technician training facilities . Subjects : Twenty female pigs and 20 Basic Life Support (BLS)-certified rescuers . Interventions , Measurements , and Main Results : Animals : Acid-base status , cerebral , and cardiovascular hemodynamics were evaluated in 18 pigs in cardiac arrest r and omized to a C : V ratio of 15:2 or 30:2 . After 6 mins of cardiac arrest and 6 mins of CPR , an ITD was added . Compared to 15:2 , 30:2 significantly increased diastolic blood pressure ( 20 ± 1 to 26 ± 1 ; p < .01 ) ; coronary perfusion pressure ( 18 ± 1 to 25 ± 2 ; p = .04 ) ; cerebral perfusion pressure ( 16 ± 3 to 18 ± 3 ; p = .07 ) ; common carotid blood flow ( 48 ± 5 to 82 ± 5 mL/min ; p < .001 ) ; end-tidal CO2 ( 7.7 ± 0.9 to 15.7 ± 2.4 ; p < .0001 ) ; and mixed venous oxygen saturation ( 26 ± 5 to 36 ± 5 , p < .05 ) . Hemodynamics improved further with the ITD . Oxygenation and arterial pH were similar . Only one of nine pigs had return of spontaneous circulation with 15:2 , vs. six of nine with 30:2 ( p < 0.03 ) . Humans : Fatigue and quality of CPR performance were evaluated in 20 BLS-certified rescuers r and omized to perform CPR for 5 mins at 15:2 or 30:2 on a recording CPR manikin . There were no significant differences in the quality of CPR performance or measurement of fatigue . Significantly more compressions per minute were delivered with 30:2 in both the animal and human studies . Conclusions : These data strongly support the contention that a ratio of 30:2 is superior to 15:2 during manual CPR and that the ITD further enhances circulation with both C : V ratios OBJECTIVE Multiple procedures performed in parallel may cause each procedure to be performed less effectively than if performed in isolation . BLS performed by prehospital providers potentially includes artificial ventilations , chest compressions , and application of an automated external defibrillator ( AED ) . This study examines the effectiveness of  artificial ventilation  and  chest compressions  both with and without an AED . METHODS Thirty-six prehospital providers participated in a prospect i ve observational study . Tested in pairs ( n=18 ) , subjects r and omly completed three , 6-min scenarios [ apneic patient with a pulse ( VENT ) , a pulseless patient ( CPR ) , and a pulseless patient with an AED available ( CPR+AED ) ] . A full-torso manikin capable of generating a carotid pulse was connected to a computer to record number of ventilations , tidal volume , flow rate , number of compressions , and compression depth . Data were analyzed by t-test , ANOVA , and Mann-Whitney U-test . RESULTS Artificial ventilation performed in isolation provided more correct ventilations than during CPR or CPR+AED ( 25.7 % , 14.2 % , 13.7 % , p=0.02 ) . Fewer ventilations were delivered during CPR and CPR+AED ( p=0.03 ) . More compressions were delivered with CPR alone vs. CPR+AED ( 51.9 , 35.7 min(-1 ) , p=0.00 ) . More correct compressions were delivered during CPR alone vs. CPR+AED ( p=0.05 ) . CONCLUSIONS Both the quality and quantity of BLS decreases as the number of procedures performed simultaneously increases . Further decrements might occur when ALS skills enter into resuscitation . These results suggest a need to automate and /or prompt the performance of BLS to optimize resuscitation Objectives : To discover the circumstances of out of hospital cardiac death irrespective of resuscitation attempts . Design : Prospect i ve community study over the two years 1994 and 1995 . Setting : The health districts of Brighton , South Glamorgan , and York , UK . Subjects : 1290 victims of sudden death or cardiac arrest caused by coronary heart disease who were under 76 years of age . Interventions : Basic and advanced life support for witnessed cardiac arrests . Main outcome measures : Survival to reach hospital and for 30 days after the arrest . Results : 35 ( 35 % ) of 101 patients ( mean age 64 ) whose arrest was witnessed by a doctor or paramedic survived for 30 days compared with 9 of 464 ( 2 % ) whose arrest was witnessed by a relative or byst and er at home ( mean age 66 ) and 15 of 200 ( 8 % ) whose arrest was witnessed in a public place ( mean age 61 ) . None of the 525 victims of an unwitnessed arrest survived but the majority of those whose arrest was witnessed had complained of new symptoms before the arrest . Victims who were given basic life support by relatives or byst and ers had better survival ( 14 of 183 ( 8 % ) ) than those who were not ( 10 of 481 ( 2 % ) , p < 0.001 ) . Of the 20 % of arrests that occurred in public places , few were in places where public access defibrillators would now be available . Conclusions : The burden of out of hospital cardiac arrest is mainly in the home but most victims have premonitory symptoms . Public education to seek help urgently for new or prolonged chest pain seems the most promising method to address the problem STUDY OBJECTIVE This study correlated the delay in initiation of byst and er cardiopulmonary resuscitation ( ByCPR ) , basic ( BLS ) or advanced cardiac ( ACLS ) life support , and transport time ( TT ) to survival from prehospital cardiac arrest . This was a secondary endpoint in a study primarily evaluating the effect of bicarbonate on survival . DESIGN Prospect i ve multicenter trial . SETTING Patients treated by urban , suburban , and rural emergency medical services ( EMS ) services . PATIENTS Eight hundred and seventy-four prehospital cardiac arrest patients . INTERVENTIONS This group underwent conventional ACLS intervention followed by empiric early administration of sodium bicarbonate noting resuscitation times . Survival was measured as the presence of vital signs on emergency department ( ED ) arrival . Data analysis utilized Student 's t-test and logistic regression ( p<0.05 ) . RESULTS Survival was improved with decreased time to BLS ( 5.52 min versus 6.81 min , p=0.047 ) and ACLS ( 7.29 min versus 9.49 min , p=0.002 ) intervention , as well as difference in time to return of spontaneous circulation ( ROSC ) . The upper limit time interval after which no patient survived was 30 min for ACLS time , and 90 min for transport time . There was no overall difference in survival except at longer arrest times when considering the primary study intervention bicarbonate administration . CONCLUSION Delay to the initiation of BLS and ACLS intervention influenced outcome from prehospital cardiac arrest negatively . There were no survivors after prolonged delay in initiation of ACLS of 30 min or greater or total resuscitation and transport time of 90 min . This result was not influenced by giving bicarbonate , the primary study intervention , except at longer arrest times OBJECTIVES To compare the quality of resuscitation between those with a simplified chest compression-only cardiopulmonary resuscitation ( CPR ) program and those with a conventional CPR program .  METHODS The participants were r and omly assigned to either the 120-min training program of chest compressions ( chest compression-only CPR ) or the 180-min training program of chest compressions and ventilations ( conventional CPR ) . Main outcome measures were the net number of appropriate chest compressions during the 2-min test period and the proportion of appropriate chest compressions over the theoretically attainable number one month after the training . RESULTS 223 participants were enrolled and 104 in each group completed this study . The 2-min number of appropriate chest compressions was 86.1+/-57.2 in the chest compression-only CPR group , which was significantly greater than 57.1+/-30.2 in the conventional CPR group ( p<0.001 ) . The proportion of appropriate chest compressions was higher in the chest compression-only CPR group than in the conventional CPR group ( 47.1+/-31.1 % versus 38.1+/-20.1 % , p=0.022 ) . Time without chest compressions during conventional CPR  reached 85.5+/-17.0 s out of 120 s , which was significantly longer than that during chest compression-only CPR ( 33.9+/-10.0 s , p<0.001 ) . The total number of ventilations and the number of appropriate ventilations during 2 min was 2.5+/-3.0 and 0.9+/-1.6 , respectively . CONCLUSIONS A simplified chest compression-only CPR program makes it possible for the general public to perform a greater number of appropriate chest compressions than the conventional CPR program ( UMIN-CTR C0000000321 ) BACKGROUND Despite a large amount of data assessing outcomes of out-of-hospital cardiac arrests ( OHCAs ) , little information is available about physician-staffed emergency medical service ( EMS ) systems . The aim of our study was to investigate the impact of a physician on the outcome of patients after OHCA . METHODS This is a prospect i ve , observational study that included 539 consecutive patients ( 63.9 + /- 19.1 years old ; 349 males ) with OHCA in the community of Dachau ( 135,000 inhabitants ) in whom resuscitation was attempted between January 2000 and January 2006 according to Utstein style . Patients were followed up to hospital discharge . The primary end point of the study was that the patients was discharged alive from hospital . RESULTS Of 412 patients with an OHCA , 180 ( 43.7 % ) were admitted to hospital , and 47 ( 11.4 % ) were discharged alive . Resuscitation was started by a physician in 117 ( 28.4 % ) patients , by a layperson in 118 ( 28.6 % ) , or by an EMS personnel in 177 ( 43.0 % ) . A total of 18 patients ( 18.6 % ) treated by physicians , 13 patients ( 8.0 % ) treated by EMS personnel ( P = .02 vs treatment by physician ) , and 16 patients ( 16.5 % ) resuscitated by laypersons were discharged from hospital ( P = .8 vs treatment by physician ) . In 105 patients with byst and er-witnessed OHCA of cardiac origin with shockable rhythm , the discharge rate was 32.4 % ( n = 34 ) . Multivariate analysis identified ventricular fibrillation on first electrocardiogram , observed OHCA , short response time intervals but not the unit that performed the first resuscitation attempt as independent predictors of survival . CONCLUSIONS A physician on board of the advanced life support 
    Output:
    
Educational polymorphisms of BLS algorithms could build unpredictable barriers between rescuers and cardiac arrest victims and might seriously limit instructors ' educational effectiveness .