Abstract
BACKGROUND:
Active compression-decompression cardiopulmonary resuscitation (ACDCPR) has been popular in the treatment of patients with cardiac arrest (CA). However, the effect of ACD-CPR versus conventional standard CPR (S-CRP) is contriversial. This study was to analyze the efficacy and safety of ACD-CPR versus S-CRP in treating CA patients.
METHODS:
Randomized or quasi-randomized controlled trials published from January 1990 to March 2011 were searched with the phrase “active compression-decompression cardiopulmonary resuscitation and cardiac arrest” in PubMed, EmBASE, and China Biomedical Document Databases. The Cochrane Library was searched for papers of meta-analysis. Restoration of spontaneous circulation (ROSC) rate, survival rate to hospital admission, survival rate at 24 hours, and survival rate to hospital discharge were considered primary outcomes, and complications after CPR were viewed as secondary outcomes. Included studies were critically appraised and estimates of effects were calculated according to the model of fixed or random effects. Inconsistency across the studies was evaluated using the I2 statistic method. Sensitivity analysis was made to determine statistical heterogeneity.
RESULTS:
Thirteen studies met the criteria for this meta-analysis. The studies included 396 adult CA patients treated by ACD-CPR and 391 patients by S-CRP. Totally 234 CA patients were found out hospitals, while the other 333 CA patients were in hospitals. Two studies were evaluated with high-quality methodology and the rest 11 studies were of poor quality. ROSC rate, survival rate at 24 hours and survival rate to hospital discharge with favorable neurological function indicated that ACD-CPR is superior to S-CRP, with relative risk (RR) values of 1.39 (95% CI 0.99–1.97), 1.94 (95% CI 1.45–2.59) and 2.80 (95% CI 1.60–5.24). No significant differences were found in survival rate to hospital admission and survival rate to hospital discharge for ACD-CPR versus S-CRP with RR values of 1.06 (95% CI 0.76–1.60) and 1.00 (95% CI 0.73–1.38).
CONCLUSION:
Quality controlled studies confirmed the superiority of ACD-CPR to S-CRP in terms of ROSC rate and survival rate at 24 hours. Compared with S-CRP, ACD-CPR could not improve survival rate to hospital admission or survival rate to hospital discharge.
KEY WORDS: Active compression-decompression, Cardiopulmonary resuscitation, Cardiac arrest, Meta-analysis
INTRODUCTION
Cardiac arrest (CA) seizes a large number of lives all around the world and causes increasing global concern. Approximately 400 000 to 460 000 people in the USA may die every year from sudden CA in the emergency department or before arrival at a hospital.[1] Standard CPR (S-CRP) has been used for cardiopulmonary resuscitation.[2] However, the mortality has not improved remarkably after S-CRP. The reported success rate of CPR ranged from 5% to 10%.[3] The reported coronary perfusion pressure (CPP), which was closely related to the successful resuscitation, was far from normal in patients with CA receiving S-CRP.[4] Active compression-decompression cardiopulmonary resuscitation (ACDCPR) with a hand-held suction device is applied on the mid sternum to compress the chest and then to actively decompress the chest after each compression. European Resuscitation Council Guidelines for Resuscitation 2010 does not recommend ACD-CPR as an option for CRP in CA patients.[5] However, recent studies demonstrated that ACD-CPR improved clinical outcome compared with S-CRP[5] and that the curative effect of ACD-CRP and S-CRP was not consistent in CA patients. Based on a systematic review and meta-analysis of the literature, we assessed existing evidences about the efficacy and safety of ACD-CRP and S-CRP in the management of CA.
METHODS
Search strategy
Studies were searched in PubMed, EmBASE, and China Biomedical Document Database from January 1990 to May 2011 by using the following terms: Active compression-decompression cardiopulmonary resuscitation, cardiac arrest, and cardiopulmonary resuscitation. The Cochrane database of systematic reviews was searched using such phrase as active compression-decompression cardiopulmonary resuscitation.
Inclusion and exclusion criteria
Inclusion criteria were as follows: 1) randomized or quasi-randomized controlled studies in adults (more than 18 years) diagnosed with CA at in-patient or out-patient clinics; 2) intervention with ACD-CRP; 3) intervention with S-CRP as control; 4) English and Chinese languages; 5) results including at least one of the following variables: ROSC rate, survival rate at 24 hours, survival rate to hospital admission, survival rate to hospital discharge, survival rate to hospital discharge without neurological impairment and complications of CPR. Exclusion criteria were as follows: 1) animal studies; 2) patients studied under 18 years old; 3) non-randomized studies; 4) studies far from our purpose of the study.
Selection of studies
The included studies were examined by two independent reviewers, and disagreements were handled by discussion.
Data extraction
Original data were extracted on a standard form, which includes: 1) the general information of selected studies, including details of study design, and randomized-blind criteria; 2) study population; 3) intervention and comparison and 4) measures of efficacy and safety.
Analysis of methodological quality and scientific evidence
The methodology in all the studies was analyzed including: 1) random distribution; 2) allocation concealment; 3) blind method if any; 4) studies lost or not; 5) quality evaluation of intention treatment. Jadad score was applied to evaluate the studies, the method was considered of low quality when the score was 1–2 and of high quality when it was 3–5.[6]
Data analysis and synthesis of results
Standard meta-analytical techniques were used to determine the efficacy and safety of ACD-CRP and S-CRP, using a model of fixed or random effects.[7] We analyzed dichotomous variables by estimation of relative risk (RR) with a 95% confidence interval as well as continuous variables by weighted mean difference (WMD) with a 95% confidence interval. The degree of inconsistency between the studies was quantified using the I2 statistical method that describes the proportion of variance across the studies because I2<50% and I2>50% reflect small and large inconsistency respectively.[8] The sensitivity of the method was analyzed to explore statistical heterogeneity.[9] As in recent studies, we did not use funnel plots to examine the possibility of publication bias.[10]
RESULTS
Searching results
In 151 articles searched, 130 were reviews and editorials, investigations, analytical studies, and case reports. Sixty animal studies were excluded and another 4 studies were excluded because their intervention groups did not use ACD-CRP. Furthermore, two studies were published in duplication. The latest study was selected. Finally, 13 randomly controlled trials were included into this meta-analysis involving 2 353 CA patients.[11–23] Thus 1 252 patients accepted ACD-CRP, and 1 252 received S-CRP (Figure 1).
Figure 1.
Searching strategy.
Included studies
Among the included studies, 4 were accomplished in Germany, 2 in France, 2 in Canada, and 1 in Australia. The rest 4 studies were conducted in the USA (2 studies) and China (2 studies). The four studies included patients with CA encountered in hospitals while the other studies included patients with CA out hospitals. Only Stiell studied both out-hospital and in-hospital CA patients. The four studies were multi-center control studies, and the other studies were single-center control studies. Stiell et al[21] studied a largest sample of 2 000 patients, while Tucker et al[23] studied 53 patients, comparatively the smallest sample. Six studies provided ROSC rate, 4 with survival rate at 24 hours, 2 with survival rate to hospital admission, 4 with survival rate to hospital discharge, and 5 with complications of CPR (Table 1).
Table 1.
General information about included studies
Methodology of the included studies
In 13 studies included in this analysis, there was no significant difference in baseline conditions. Four studies described the details of randomization. Only one study provided double blind allocation, while the rest did not mention it. In four studies using concealed allocation, only two were appropriate. According to Jadad scoring, more than three scores were found in two studies which were considered of high-quality methodology, while the rest studies were not satisfied with scores fewer than 3 (Table 2).
Table 2.
Quality of the included studies
ROSC rate
Six studies provided specific data on ROSC rate. The ACD-CRP group included 566 patients, and the S-CRP group consisted of 585 patients. There was significant difference among the studies (P=0.002, I2=74.4%). The calculated RR merger was 1.39 (95% CI 0.99–1.97), and analysis showed a significant improvement of ROSC rate in the ACD-CRP group compared with the S-CRP group (Figure 2).
Figure 2.
Comparison of ROSC rate between the ACD-CPR group and the S-CPR group.
Survival rate to hospital admission
Two studies provided specific data on survival rate to hospital admission for out hospital patients. The ACD-CRP group included 162 patients and the S-CRP group comprised 160 patients. No statistical heterogeneity was seen in the studies (P=0.45, I2=0%), so the model of fixed effects was used for analysis. The calculated OR merger was 1.06 (95% CI 0.76–1.60), and joint analysis also showed no significant difference in survival rate to hospital admission in the ACD-CRP group compared with the S-CRP group (Figure 3).
Figure 3.
Comparison of hospital admission rate between the ACD-CPR group and the S-CPR group.
Survival rate at 24 hours
Four studies provided specific data on survival rate at 24 hours. The ACD-CRP group included 417 patients, and the S-CRP group 428 patients. No significant heterogeneity was seen in the studies (P=0.78, I2=0%), thus random effects were analyzed. The calculated OR merger was 1.94 (95% CI 1.45–2.59), and joint analysis also showed a significant improvement in survival rate at 24 hours in the ACD-CRP group compared with the S-CRP group (Figure 4).
Figure 4.
Survival rate comparison at 24 hours between the ACD-CPR group and the S-CPR group.
Survival rate to hospital discharge
Four studies provided specific data on survival rate to hospital discharge. The ACD-CRP group included 608 patients and the S-CRP group 583 patients. No statistically heterogeneity was found in the studies (P=0.39, I2=0.9%), thus fixed effects were analyzed. The calculated RR merger was 1.00 (95% CI 0.73–1.38), and joint analysis also showed no significant difference in survival rate to hospital discharge in the ACD-CRP group compared with the S-CRP group (Figure 5).
Figure 5.
Hospital discharge rate comparison between the ACD-CPR group and the S-CPR group.
Complications of CPR
Five studies described complications after CPR; however, data were difficult to collect for analysis. Instead, descriptive studies were used for evaluating complications after CPR. It was reported that there were more sternal fractures and rib fractures (13/15 vs. 11/20; P<0.05) in ACD-CPR patients than in STD-CPR patients (14/15 vs. 6/20; P<0.005). Also sternal dislodgements (2.9% vs. 0.4%, P=0.03) and hemoptysis (5.4% vs. 1.3%, P=0.01) were more frequent in ACD ACLS patients. Others found that there was no difference in the incidence of complications caused by CPR.
DISCUSSION
The American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care 2010 recommend premier selection of standard CPR for CA patients in and out of hospital.[2] However, studies showed that standard CPR can only supply vital organs with limited blood pressure (BP),[24] even specialists are unable to perform high-quality resuscitation because of energy consumption.[25] The overall survival rate after cardiac arrest remains low. In 74 studies involving 36 communities as reported, the survival rate ranged from 2% to 44%.[26] The increase of CPP was found to be closely related to successful resuscitation.[2] Chest expansion after segues can suck blood into the heart where blood is ready for the next pump. The more the chest is expanded, the more cardiac output is given. During ACD-CPR, positive and negative pressures are used alternately to the chest by a “plunger” that forms a seal with the anterior chest wall. Several studies found that ACD-CPR produced better hemodynamic effects than standard CPR in patients,[27–29] but there were exceptions.[30]
The results of this meta-analysis indicate that ACD-CPR is superior to STD-CPR for CA patients in terms of ROSC rate, survival rate at 24 hours, and admission rate. However, survival rate to hospital discharge is not statistically significant. ACD-CPR can be used to impove the neurological outcome at discharge or to produce a better long-term outcome. This finding is not consistent with the published meta-analyses, suggesting that ACD-CPR is not beneficial to patients with CA.[31] This meta-analysis showed an increased rate of complications including sternal fracture which might be associated with ACD-CPR. Sternal fracture is unlikely to increase mortality because it causes no severe internal organ damage.
In this meta-analysis, methodological quality was not high in most of quasi-randomized controlled trials because only Chinese and English articles were reviewed. Large-scale multi-center randomized, controlled clinical studies on ACD-CRP for CA patients are needed.
The price of ACD-CPR device is acceptable for any hospital. However, the efficacy of ACD-CPR may be highly dependent on the quality and duration of training.[32]
In conclusion, compared with S-CPR, ACD–CPR can improve the ROSC rate and survival rate at 24 hours. There is no difference in hospital admission rate and hospital discharge rate between S-CPR and ACD-CPR patients. More studies are needed to provide sufficient evidence for clinical practice.
Footnotes
Funding: None.
Ethical approval: Not needed.
Conflicts of interest: The authors declare that there is no conflict of interest.
Contributors: Luo XR proposed the study, analyzed the data and wrote the first draft. All authors contributed to the design and interpretation of the study and to further drafts.
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