American Journal of Emergency Medicine (2012) 30, 784-793

Review

Cardiocerebral resuscitation vs cardiopulmonary resuscitation for cardiac arrest: a systematic review

Yang Chen-lu PhD ^a,1, Wen Jin PhD ^b,?,1, Li You-ping MSc ^c, Shi Ying-kang MSc ^d,?

^aWest China Medical School, Sichuan University, Guoxue Xiang, Chengdu 610041, China

^bDepartment of Hospital Management & Health Policy, West China Hospital, Sichuan University, Chengdu 610041, China

^cThe Chinese Evidence-Based Medicine Center & Department of Clinical Epidemiology, West China Hospital,

Sichuan University, Guoxue Xiang, Chengdu 610041, China

^dDepartment of Thoracic & Cardiovascular Surgery, West China Hospital, Sichuan University, Chengdu 610041, China

Received 17 October 2010; revised 24 February 2011; accepted 25 February 2011

Abstract

Objective: The objective of this study is to evaluate the efficacy of cardiocerebral resuscitation (CCR) vs cardiopulmonary resuscitation (CPR) for patients with out-of-hospital cardiac arrest (OHCA).

Methods: We conducted a systematic review of controlled trials and observational studies. We searched Cochrane Central Register of Controlled Trials; MEDLINE; Embase; and Chinese databases such as VIP, CNKI, WANFANG, and CBM from their inception to September 2010. Data from original studies were extracted and assessed with predefined criteria.

Results: Thirteen studies comprising 3 randomized controlled trials and 10 observational studies were included. Pooled analysis of 4 observational studies suggested that Neurologically intact survival of patients with OHCA was improved in CCR group (odds ratio [OR], 1.45; 95% confidence interval [CI], 1.07-1.97). Survival to hospital discharge in the CCR group was superior or at least equal to that in CPR group (randomized controlled trial OR, 1.25; 95% CI, 1.01-1.55; cohort studies OR, 1.15; 95% CI, 0.72- 1.82; Case-control studies OR 0.85; 95% CI, 0.65-1.12). In the subgroup analysis of patients with a shockable rhythm as an initial rhythm, survival to hospital discharge was significantly improved in the CCR group (cohort studies OR, 2.03; 95% CI, 1.44-2.86). However, when only nonCardiac origin cardiac arrest was taken into consideration, survival rate was better in the CPR group (cohort studies OR, 0.87; 95% CI, 0.77-0.98).

Conclusion: Cardiocerebral resuscitation might be equivalent or superior to CPR in patients with OHCA in both survival rate and neurologic benefits. Further work is needed to assess the efficacy of CCR for victims who had OHCA of noncardiac causes.

(C) 2012

* Corresponding authors. Shi Ying-kang, MSc, and Wen Jin, PhD, Sichuan University, Guoxue Xiang, Chengdu 610041, China. Tel.: +86 28 13666224598; fax: +86 28 85422253.

E-mail addresses: [email protected] (Wen J.), [email protected] (Shi Y.K.).

¹ The first 2 authors, Yang Chen-lu and Wen Jin, contributed equally to this article.

Introduction

Cardiopulmonary resuscitation (CPR) by bystanders with both chest compressions and mouth-to-mouth ventilation has been widely used as a standard approach to treat patients having out-of-hospital cardiac arrest (OHCA) ever since it was introduced in the 1960s [1]. However, the ratio of

0735-6757/$ - see front matter (C) 2012 doi:10.1016/j.ajem.2011.02.035

compression to ventilation in CPR has always been a point of debate. In the 2000 American Heart Association (AHA) Guidelines for CPR and Emergency Cardiac Care [2], the recommended ratio is 15:2. However, the survival rate of patients with OHCA has yet to be optimal especially when the Neurologically favorable survival was considered over the years [3-8]. As a result, the AHA reappraised the effect of ventilation in CPR and changed the recommended ratio to 30:2 in 2005 with the following statement, “Laypersons should be encouraged to do compression-only CPR if they are unable or unwilling to provide rescue breaths” [9].

Developed by the University of Arizona Sarver Heart Center Resuscitation Group, cardiocerebral resuscitation (CCR) or compression-only CPR [10] is a relatively new approach for patients with OHCA [11,12]. Compared with CPR, CCR is easier to be managed and may bring about more neurologic benefits, which have made it increasingly popular worldwide in recent years. So far, the study of Bobrow et al [13] has showed the efficacy of CCR in improving survival with favorably neurologic function rate in OHCA; but some other studies found no difference between the two [6,7,14-16]. Because it is essential for emergency rescuers to know whether the benefits of CCR are strongly evidenced, we performed this systematic review to examine the efficacy of it in patients with OHCA by summarizing the current human evidence.

Methods

Eligibility criteria

We selected studies in accordance with the following criteria: (1) types of studies: randomized controlled trial (RCT), controlled clinical trial, or observational study; (2) participants: human beings having OHCA; (3) interventions: CCR and CPR; and (4) outcomes: survival rate and neurologic benefits. The neurologic status of patients was assessed with Cerebral performance categories score [13,17]. A CPC score of 1 indicates good cerebral performance; score of 2, moderate cerebral disability; score of 3, severe cerebral disability (eg, depending on others for daily support because of impaired brain function); score of 4, coma or vegetative state; and score of 5, brain death. In our analysis, a CPC score of 1 or 2 was considered Favorable neurologic outcome.

Data sources and search strategies

We searched English articles in the Cochrane Central Register of Controlled Trials (September 2010), MEDLINE (1950 to September 2010), and Embase (1966 to September 2010) using the following search strategies: CCR, OR chest compression only, OR hands only, OR Continuous chest compression, OR continuous chest compressions, OR chest

compression alone, and OR cardiac-only resuscitation. We also searched Chinese language electronic databases: Chinese Biomedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), and Chinese Sci & Tech Journals (VIP).

Study selection and data collection process

Two authors (Y.C.L. and W.J.) reviewed the results of the search and obtained full articles of the potentially eligible studies. The 2 authors independently assessed the studies for inclusion and the quality of eligible studies. We extracted relevant data with a Standardized reporting form. Discrepancies were resolved through discussion between the authors. In case of different opinions, a third reviewer (L.Y.P.) was consulted for consensus.

Quality assessment

According to the recommendation of the Cochrane Handbook for Systematic Reviews of Interventions [18], we assessed the quality of RCTs using the following predefined items: (1) randomization, (2) allocation concealment, (3) blinded outcome assessment, (4) reporting loss to follow-up/ withdrawal, and (5) comparability of baseline.

We assessed the quality of observational studies with a specific checklist including the following items [19]: (1) if characteristics of the participants were described; (2) if cases and controls were drawn from the same population; (3) if the comparability of baseline was described; (4) if measures of association were presented (odds ratio [OR]/risk ratio), including 95% confidence interval [CIs] and numbers in the analysis (totals); (5) if lost to follow-up was described; (6) if potential confounders were described; (7) if the recruitments of cases and controls were in the same time frame; and (8) if there were clear inclusion and exclusion criteria.

Data analysis

Results of the studies were summed up to calculate the OR for dichotomous outcomes and weighted mean differ- ences for continuous outcomes, along with 95% CIs. P <= .05 was considered statistically significant. Heterogeneity among studies was evaluated by ?2 test and I² statistics. A P value of <=.1 was considered to indicate statistical heterogeneity among studies. "I²” denotes the percentage of total variation across the studies that is the result of heterogeneity rather than chance (a I² value of 0% denotes no observed heterogeneity, and greater I² values denote increasing heterogeneity). If there was no statistical hetero- geneity among studies, a pooled outcome of intervention was calculated with a fixed effect model. If there was statistical heterogeneity among studies, a subgroup analysis was conducted to spot the sources of heterogeneity (eg, trial quality); and if necessary, a random effect model would be adopted. We planned to assess the potential publication bias

Survival to hospital admission“>by using a funnel plot, if possible. All statistical analyses of included studies were performed with Review Manager 5.0 (The Cochrane Collaboration, Oxford, England).

Subgroup analysis was planned for (1) whether the patients had an Initial shockable rhythm (ventricular tachycardia or ventricular fibrillation) and (2) cause of cardiac arrest: cardiac causes or noncardiac causes (such as trauma, drowning, drug overdose, asphyxia, respiratory diseases, and cerebrovascular diseases) [20].

If a study appears to be an outlier (has results very different from the rest of the studies), then its influence on a meta-analysis in this study will be assessed by excluding it (sensitivity analysis).

Results

Study selection and quality assessment

The electronic search identified a total of 261 studies, of which 89 were potentially eligible based on their titles and abstracts. Finally, we included 13 [4-7,13,15,20-26] studies containing 3 RCTs and 10 observational studies (Fig. 1).

Characteristics of the included studies are summarized in Table 1. All included studies were assessed for quality (Tables 2-3).

We were only able to do funnel plot analysis for our primary outcome of survival to hospital discharge rate because of the limited number of included studies. Upon visual inspection of the funnel plot for survival to hospital discharge, we found evidence of publication bias for cohort studies (Fig. 2).

Outcomes

All the studies (n = 38 230) reported survival rate, of which 5 observational studies (n = 21 462) and 1 RCT (n = 1s286) reported neurologic function status of the survival, which was evaluated with a Cerebral performance category score mentioned [27] above.

Survival to hospital admission

Six studies (n = 14 943) reported survival to Hospital admission rate. These studies included 668 survivals (23.1%) in 2895 individuals in CCR group and 2461 survivals (20.4%) in 12 048 individuals in CPR group. No significant difference was identified in survival to hospital admission rate between the 2 groups when they were analyzed according to the study design, respectively (RCT OR, 1.30; 95% CI, 0.91-1.86; cohort studies OR, 1.14;

95% CI 0.72-1.78; case-control studies OR, 0.92; 95% CI,

0.69-1.22) (Fig. 3). In a sensitivity analysis excluding 1

study [13] (OR, 1.58; 95% CI, 1.27-1.98), the pooled OR

(95% CI) of cohort studies was 0.90 (0.71-1.14).

Survival to hospital discharge

Survival to hospital discharge was defined as the patient leaving the hospital alive or survival to 30 days postcardiac arrest, whichever came first [15]. Meta-analysis of 3 RCTs (n = 3031) showed better outcome in the CCR group (OR, 1.25; 95% CI, 1.01-1.55), but the results of 7 cohort studies

(n = 7985) and 2 case-control studies (n = 10 158) showed no significant difference (cohort studies OR, 1.15; 95% CI,

Fig. 1 Flow chart of studies through Selection process.

Cardiocerebral resuscitation for cardiac arrest

787

Table 1 Characteristics of included human studies

Trial	Country	Study Trial period design	No. of participants	Mean age (SD, y)	Participants	Primary outcome
Rea et al [26],	United States	RCT 2004-2009	G1: 960	G1: 63.9 +- 16.3	OHCA, adult victims excluding	Survival to hospital
2010	and England		G2: 981	G2: 63.4 +- 16.5	arrest due to trauma, drowning,	discharge, survival to hospital
					or asphyxiation	discharge with favorable
						neurologic outcome
Svensson et al [25],	Sweden	RCT 2005.2-2009.1	G1: 656	G1: 67	OHCA, adult victims excluding	Survival to hospital discharge
2010			G2: 620	G2: 68	arrest due to trauma, drowning,
					or asphyxiation
Hallstrom et al [5],	United States	RCT ?-1998.8	G1: 279	G1: 68.5	OHCA, adult victims excluding	Survival to hospital discharge
2000			G2: 241	G2: 67.9	poisoning and overdoses
Kitamura et al [20],	Japan	Cohort study 2005.1-2007.12	G1: 7474	G1: 75.7 (75.3-76.1)	All adult cardiac arrests of	1-mo survival with favorable
2010			G2: 8878	G2: 74.6 (74.2-74.9)	noncardiac causes	neurologic outcome
Bobrow et al [13],	United States	Cohort study 2005.1-2007.11	G1: 1799	G1: 67.8 (15.0) G2: 65.7 (15.4)	All adult cardiac arrests, cardiac	Survival to hospital discharge,
2008			G2: 661		and noncardiac causes	survival to hospital
						discharge with favorable
						neurologic outcome
Kellum et al [23],	United States	Cohort study 2004-2007	G1: 22	Unknown	All witnessed adult cardiac arrest	Survival to hospital discharge
2008			G2: 16		with an initially shockable rhythm
Holmberg et al [4],	Sweden	Cohort study ?-1995	G1: 1812	Unknown	All adult cardiac arrests, cardiac	1-mo survival
2001			G2: 278		and noncardiac causes
Iwami et al [7],	Japan	Cohort study 1998.5-2003.4	G1: 783	G1: 69.1 (16.1) G2: 68.2 (15.3)	All witnessed adult cardiac arrest	1-mo survival, 1-y survival
2007			G2: 544		of presumed cardiac origin	with favorable neurologic
						outcome
Ong et al [15],	Singapore	Cohort study 2001.10-2004.10	G1: 287	G1: 56.0 (20.1) G2: 58.6 (15.8)	All adult cardiac arrests, cardiac	Survival to hospital discharge,
2008			G2: 154		and noncardiac causes	30-d survival with favorable
						neurologic outcome
SOS [6], 2007	Japan	Cohort study 2002.9-2003.12	G1:712	G1:68(55-80) G2:69(55-80)	All adult cardiac arrests, cardiac	30-d survival with favorable
			G2:439		and noncardiac causes	neurologic outcome
Waalewijn	Netherlands	Cohort study 1995.1-1997.8	G1: 437	Unknown	All bystander witnessed	Survival to hospital discharge
et al [24], 2001			G2: 41		adult cardiac arrests with
					EMS resuscitation
Van Hoeyweghen	Belgium	Case-control 1983-1989	G1: 544	Unknown	All adult cardiac arrests,	14-d survival
et al [21], 1993		study	G2: 263		cardiac and noncardiac causes
Bohm et al [22],	Sweden	Case-control 1990-2005	G1: 8209	G1: 63 (18)	All adult cardiac arrests,	1-mo survival
2007		study	G2: 1145	G2: 66 (16)	cardiac and noncardiac causes
G1 indicates CPR group; G2, CCR group; EMS, emergency medical services.

Table 2 Quality assessment of included RCT

Trial Randomization

Rea et al [26], 2010

Svensson et al [25], 2010

Hallstrom et al [5], 2000

A B A

Allocation concealment

A B C

Blinded outcome assessment

B B B

Reporting loss to follow-up/withdrawal

A A A

Comparability of baseline

A A A

Randomization: A indicates adequate; B, unclear (reported randomization but method not described); C, inadequate (quasi-random method of allocation, such as alternation, date of birth, or case record number and other); D, not mentioned. Allocation concealment: A indicates adequate; B, unclear (not mentioned); C, clearly inadequate concealment/not used. Blinding: A indicates adequate (double-blind or blinding the outcomes evaluators); B, partly blinded/unclear (single-blind or not mentioned); C, not used (“open label” or “unmask’). Reporting loss to follow-up/withdrawal: A indicates adequate reporting (including numbers and causes); B, partly reported; C, not reported. Comparability of baseline: A indicates comparable (at least including age); B, unclear; C, not comparable.

0.72-1.82; case-control, OR, 0.85; 95% CI, 0.65-1.18)

(Fig. 4). In a sensitivity analysis excluding 1 study [13] (OR, 2.50; 95% CI, 1.75-3.58), the pooled OR (95% CI)

of cohort studies was 0.94 (0.73-1.21).

Survival with favorable neurologic outcome

There were 4 observational studies (n = 5110) and 1 RCT (n = 1286) concerning the neurologic benefits of CCR vs CPR. They showed that CCR by bystanders is equivalent or superior to conventional CPR in adult patients with OHCA

Table 3 Quality assessment of included observational studies

(RCT OR, 1.29; 95% CI, 0.93-1.79; cohort studies OR, 1.45;

95% CI, 1.07-1.97) (Fig. 5). In a sensitivity analysis

excluding 1 study [13] (OR, 1.95; 95% CI, 1.19-3.18), the pooled OR (95% CI) of cohort studies was 1.23 (0.83-1.80).

Subgroup analysis

Patients with a shockable rhythm as an initial rhythm

One RCT, 5 cohort studies, and 1 case-control trial reported survival to hospital discharge rate of patients with a

Trial	Clear inclusion/ exclusion citeria	Participants’ characteristics described	Case/controls drawn from the same population	Comparability of baseline	If measures of association are presented (OR/RR), including 95% CIs and numbers in the analysis (totals)	Loss to follow-up	Potential confounders described	Recruitment of case/control over same time frame
Kitamura et al [20],	Y	Y	Y	Y	Y	Y	Y	Y
2010
Van Hoeyweghen	Y	N	Y	N	N	UN	N	Y
et al [21], 1993
Bohm et al [22],	Y	Y	Y	Y	Y	UN	Y	Y
2007
Bobrow et al [13],	N	Y	Y	Y	Y	N	Y	N
2008
Kellum et al [23],	Y	Y	Y	Y	Y	N	Y	N
2008
Holmberg et al [4],	Y	Y	Y	N	Y	N	Y	Y
2001
Iwami et al [7],	Y	Y	Y	Y	Y	Y	Y	Y
2007
Ong et al [15],	Y	Y	Y	Y	Y	N	N	Y
2008
SOS [6], 2007	Y	Y	Y	Y	Y	Y	N	Y
Waalewijn et al	Y	N	Y	N	Y	N	N	Y
[24], 2001
RR indicates risk ratio; Y, yes; N, no; UN, unclear.

Fig. 2 Funnel plot for survival to hospital discharge rate of cohort studies.

shockable rhythm (ventricular fibrillation or ventricular tachycardia) as an initial rhythm. Pooled result of the 5 cohort studies showed significant improvement in the survival to hospital discharge rate in the CCR group (OR, 2.03; 95% CI, 1.44-2.86) (Table 4). In a sensitivity analysis

excluding 1 study [13] (OR, 2.94; 95% CI, 1.82-4.74), the pooled OR (95% CI) of cohort studies was 1.43 (0.87-2.33). Meanwhile, studies of Van Hoeyweghen et al [21] and Iwami et al [7], respectively, reported that patients receiving CCR tend to have a better chance of getting an initial shockable rhythm (Van Hoeyweghen et al OR, 1.52; 95% CI, 1.13-2.04; Iwami et al OR 1.09; 95% CI, 0.83-1.41). Only 1

RCT and 2 cohort studies highlighted neurologic status at discharge, and the outcome showed better results in the CCR group, yet, without significant difference.

Patients having cardiac arrest of noncardiac origin One RCT and 3 cohort studies reported outcomes of patients having arrests of noncardiac causes. Pooled results of 2 cohort studies showed better survival rate in the CPR group (OR, 0.87; 95% CI, 0.77-0.98). The ORs for all other

comparisons showed no significant difference (Table 5).

Discussion

This systematic review showed that CCR might be superior to or, statistically speaking, not different from CPR for patients with OHCA in survival. The pooled result of 4 observational studies revealed that neurologically intact survival of patients with OHCA was significantly improved in CCR recipients.

According to several previous studies [14,28-30], the neurologic outcome of patients having OHCA mainly depends on the blood flow to the brain during the rescue. Chest compressions create blood flow to brain by compres- sing the chest and increasing intrathoracic pressure and, thus, deliver a small but critical amount of oxygen and substrate to the brain. However, this critical cerebral perfusion is lost when the rescuer stops chest compressions for mouth-to- mouth ventilation [28,29].

In our subgroup concerning patients who had a shockable rhythm as an initial rhythm, the CCR group tended to yield benefits, which means initial rhythm might be related to the prognosis in OHCA. Our finding is grounded on several studies [6,13,26]. Meanwhile, 2 studies (Van Hoeyweghen et al [21] and Iwami et al [7]) reported tendency in patients receiving CCR to have a bigger opportunity of getting an initial shockable rhythm. Nevertheless, 2 studies with relatively small

Fig. 3 Effects of CCR vs CPR on survival to hospital admission of patients having cardiac arrests.

Fig. 4 Effects of CCR vs CPR on survival to hospital discharge of patients having cardiac arrests. (?Van Hoeyweghen et al [21] took 14-day survival as an end point).

sample sizes could not come to a final conclusion. We hope that more studies in this field will be conducted in the future to see whether it is a general phenomenon.

Whether it is suitable to perform CCR for victims who have OHCA of noncardiac causes such as airway obstruction or drowning has touched off a heated controversy in recent years [31]. According to the previous AHA guidelines, rescue ventilation is an important part of basic life support especially for patients having noncardiac caused cardiac arrest [9]. Some experts said that, for such victims, respiratory problem is the primary cause of arrest [32]; so

ventilation plays a key role in resuscitation. In our analysis of such condition, CPR indeed performed better than CCR. Even so, given that the frequency of survival and the favorable neurologic outcome were extremely low in both the CCR and CPR groups, further study is needed to judge which one is better.

Although Figs. 3-5 showed that, in cohort studies, there was a trend toward benefit with CCR, we noticed that the positive results might be driven by data from the study of Bobrow et al [13]. Consequently, we performed a sensitivity analysis excluding that study to explore its influence on the

Fig. 5 Effects of CCR vs CPR on survival with favorable neurologic function.

Table 4 Subgroup analysis of patients with a shockable rhythm as an initial rhythm
Outcome	RCT No. of studies	OR a (95% CI)		Cohort study No. of studies	OR a (95% CI)		Case-control study No. of studies OR a (95% CI)
Survival to hospital discharge	1	1.35 (0.96-1.92)		4	2.03 (1.44-2.86)		1 0.69 (0.40-1.19)
Favorable neurologic function	1	1.42 (0.95-2.13)		2	1.47 (0.91-2.36)		- -
a Greater than 1 indicates favors CCR; less than 1, favors CPR.

meta-analysis. We found that exclusion of that study caused several statistical differences in 2 pooled outcomes (the outcome of CCR vs CPR on survival with favorable neurologic function and that of subgroup analysis of patients with a shockable rhythm as an initial rhythm), as described in the Results above. We have carefully reviewed the article of Bobrow et al [13] and noticed that his study involved training for minimally interrupted chest compression as well as other changes in emergency medical service such as early administration of epinephrine and delayed endotracheal intubation, which were not emphasized in other studies. However, whether these measures could affect the efficacy of CCR to that extent needs to be confirmed in the future.

The time interval between patients starting having OHCA and the start of resuscitation, which consists of the intervals from collapse to the start of CPR and from collapse to defibrillation, is one of the possibly confounders that may affect the validity of the analyzed results. Herlitz et al [33] reported that the time interval between collapse and arrival of the rescuer is a major contributor to a better survival rate after OHCA. Nevertheless, in our review, we failed to perform a subgroup analysis because only 4 observational studies reported results separately by time intervals and, what is more, the reported intervals had varying durations. Similarly, several previous studies have demonstrated that Prolonged ventricular fibrillation is quite different from short-time ventricular fibrillation in regard to the prognosis of OHCA [6,30,34-37]. Although we are willing to set up a subgroup to analyze this factor, we found most of the raw studies lacked related data. As a result, in this review, we analyzed all kinds of OHCA at the same time, given that, in real emergency cases, it is always hard for rescuers to tell exactly when the victims collapsed; thus, a general observance of the efficacy of CCR may offer a practical evidence for bystander resuscitation providers.

quality of CCR/CPR by bystanders was an important factor that may affect the prognosis for patients. Three prior studies have demonstrated that poor-quality resuscitation

gives no benefit to victims compared with no CPR at all [21,38,39]. In this review, few primary studies reported their outcomes separately by Quality of resuscitation; and it just seemed impossible for us to evaluate the quality of rescuers’ performance in every case; therefore, at present, we were not able to set a subgroup to analyze this factor. Nonetheless, quality of rescuers might be a possible clinical heterogeneity in this field; and we hope future research could be designed more precisely to reduce it.

In recent years, postresuscitation care, especially thera- peutic hypothermia, is being rapidly accepted around the world. Some recent studies [40-43] have shown that mild therapeutic hypothermia can produce better outcomes for patients with OHCA, particularly for a good Neurologic recovery. However, in our case, only 4 primary studies [6,13,15,23] mentioned postresuscitation care; and all of them lack data on the impact of inhospital therapeutic hypothermia. For postresuscitation care may affect neuro- logic benefits, we hope that further studies will take it into account and that a better neurologic status can be achieved by receiving a combination of CCR and good postresuscita- tion therapy.

This review has some limitations. On one hand, owing to the fact that the event in this study was an emergent situation, in which expecting patients with identical baseline was not possible and, thus, some clinical heterogeneity might exist, therefore, results must be interpreted with caution. However, this clinical heterogeneity here reflected the resuscitation condition in the real world exactly. Importantly, the studies reviewed were carried out in out-of-hospital situation; and the results may not be generalized to inpatient settings.

On the other hand, the evidence was far from complete; and the quality, far from satisfied. We only obtained 3 RCTs with small sample sizes in this field. The results should be interpreted with caution, therefore; and our findings are expected to be confirmed in more RCTs later. Furthermore, the funnel plot demonstrated asymmetry, which suggested that publication bias may exist.

Table 5 Subgroup analysis of patients having arrests due to noncardiac causes
Outcome	RCT No. of trials	OR a (95% CI)		Cohort study No. of studies	OR a (95% CI)
Survival to hospital discharge	1	0.68 (0.33-1.39)		2	0.87 (0.77-0.98)
Favorable neurologic function	1	0.63 (0.26-1.51)		2	0.82 (0.65-1.04)
a Greater than 1 indicates favors CCR; less than 1, favors CPR.

In 2008, the AHA committee recommended CCR for adults who suddenly collapse [31]. This study reviews the qualities and results of current research in this field and provides the current best evidence for the recommendation. From our perspective, CCR is better than CPR in at least 2 main aspects: first, because most bystanders are unwilling or unable to perform conventional CPR [4,7,15,22,28,44], the reason of which has something to do with the fear of contracting infectious diseases according to previous sur- veys, we infer that the potential rescuers will be more willing to provide compression only CCR; second, it is doubtless that CCR is more convenient to be taught to and performed by the public. Besides, we also provide the relatively comprehensive and objective evidence in this field, which could be considered as a reference for future research.

Conclusions

This systematic review demonstrates that bystander CCR might be equivalent or superior to CPR in patients with OHCA. Further work is needed to assess the efficacy of CCR for patients with OHCA of noncardiac causes.

Acknowledgments

The National High Technology Research and Develop- ment Program (“863” Program) of China (Grant No. 2008AA022503 and 2008AA022501), China Post-doctoral Science Foundation (Grant No. 20090461341), the Scientific Research Starting Foundation for Young Teachers in Sichuan University (Grant No. 2009SCU11172), and the National Natural Science Foundation of China (Grant No. 81072376) financially supported this study. The authors are beholden to the Foundations for their support of this work.

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