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Emergency Department, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100730, China
Summarise the evidence regarding the safety of mechanical and manual chest compressions for cardiac arrest patients.
Methods
Two investigators separately screened the articles of EMBASE, PubMed, and Cochrane Central databases. Cohort studies and randomized clinical trials (RCTs) that evaluated the safety of mechanical (LUCAS or AutoPulse) and manual chest compressions in cardiac arrest patients were included. A meta-analysis was performed using a random effects model to calculate the pooled odds ratios (ORs) and their 95% confidence intervals (CIs). The primary outcome was the rate of overall compression-induced injuries. The secondary outcomes included the incidence of life-threatening injuries, skeletal fractures, visceral injuries, and other soft tissue injuries.
Results
The meta-analysis included 11 trials involving 2,818 patients. A significantly higher rate of overall compression-induced injuries was found for mechanical compressions than manual compressions (OR, 1.29; 95% CI, 1.19–1.41), while there was no significant difference between the two groups in respect of the rate of life-threatening injuries. Furthermore, both modalities shared similar incidences of sternal fractures, vertebral fractures, lung, spleen, and kidney injuries. However, compared to mechanical compressions, manual compressions were shown to present a reduced risk of posterior rib fractures, and heart and liver lesions.
Conclusions
The findings suggested that manual compressions could decrease the risk of compression-induced injuries compared to mechanical compressions in cardiac arrest patients. Interestingly, mechanical compressions have not increased the risk of life-threatening injuries, whereas additional high-quality RCTs are needed to further verify the safety of mechanical chest devices.
Researchers have persevered in exploring the optimal depth and frequency of chest compressions during the past few decades, leading to the American Heart Association recommending chest compressions to be made to a depth of 5–6 cm and at a frequency of 100–120/min in its Guidelines for CPR.
Part 3: Adult Basic and Advanced Life Support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
However, many disadvantages of manual compressions were subsequently found, such as inappropriate depth and frequency, and especially, frequent prolonged interruptions.
To resolve these problems, researchers developed various mechanical devices to assist with CPR in cardiac arrest situations, aiming to achieve specific rates and depths which were in turn expected to improve outcomes.
Application of mechanical cardiopulmonary resuscitation devices and their value in out-of-hospital cardiac arrest: A retrospective analysis of the German Resuscitation Registry.
Two among these mechanical devices are currently widely used worldwide: the Lund University Cardiac Assist System (LUCAS) and the AutoPulse. The LUCAS is a piston-based device that provides compressions and active decompressions via a suction cup placed at the center of the chest. The AutoPulse system
applies force to a broad area of the chest by tightening a load-distributing band (LDB) which rhythmically compresses and constrains the chest wall. While mechanical compressions appear to relieve medical teams performing CPR, their routine use was not explicitly recommended according to European Resuscitation Council guidelines
. Furthermore, the most recent randomized clinical trials (RCTs) failed to demonstrate improved patient survival rates with mechanical CPR compared to manual CPR controls,
Mechanical chest compression with LUCAS device does not improve clinical outcome in out-of-hospital cardiac arrest patients: A systematic review and meta-analysis.
regrettably even suggested that mechanical compressions appeared to be associated with higher incidences of injuries compared to manual CPR, which may have been associated with survival outcomes. Moreover, some currently available reports focused on efficacy rather than safety of compressions, resulting in lower reporting of incidence of injury than the safety centered studies
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
. Previous articles report that mechanical compressions induced more cutaneous abrasions, rib and sternal fractures, lesions to abdominal and thoracic organs, and even life-threatening injuries, compared to manual compressions.
we carried out a meta-analysis of those studies that focused on safety to investigate systematically whether cardiac arrest patients treated with mechanical chest compressions had incurred more injuries than those receiving manual chest compressions.
Methods
The study was conducted in conformity with the preferred reporting items for Systematic Reviews and Meta-Analyses.
The protocol of this study was registered at https://inplasy.com/, with a registration number of INPLASY2020110111.
Screening of relevant research
A flow chart of the filtering program of relevant studies is shown in Fig. 1. All articles available in the English language and published in the PubMed, Cochrane Central, or EMBASE databases from incipiency to May 30, 2020 were searched individually. The method combining Title/Abstract keywords and Mesh/Emtree was adopted. The search terms were “cardiac arrest”, “chest compression”, “LUCAS”, “AutoPulse”, “LDB”, and “injuries”. A detailed search strategy is presented in Supplementary data 1.
Inclusion criteria for studies to be considered eligible for this meta-analysis were: (1) the study participants included were adult patients with cardiac arrest; (2) the comparative arms of the study were mechanical chest compressions (LUCAS or AutoPulse) and manual chest compressions; (3) the studies were cohort studies or RCTs; (4) the study papers were written in English; (5) the studies measured compression-induced injuries, and the injuries were determined by autopsy, post-mortem computed tomography (PMCT), or dedicated imaging. Based on meta-analysis exclusion criteria, articles were excluded if: (1) the study lacked outcome data; (2) only the abstract of the original study was available; (3) only a citation of or report on the study within another publication could be found; (4) the full text of the article could not be obtained.
Outcomes
Primary outcome was the rate of overall compression-induced injuries. Secondary outcomes included the incidence of life-threatening injuries, skeletal fractures such as sternal, rib, vertebral fractures, visceral injuries such as lung, heart, liver, spleen, kidney lesions, and other soft tissue injuries.
Research selection and data extraction
All the available articles were selected in accordance with the above-mentioned inclusion and exclusion criteria by two independent researchers (YWY and HYL). Any discrepancies identified were discussed with YXG. Relevant data, including first author’s first name, host country of the study, study design type, study period, study participants, number of experimental arms and control arms, type of mechanical device, and methods of identifying injuries, were extracted from the original studies.
Risk of bias assessment
Assessment of the risk of bias for RCTs was based on the principle of the Cochrane Collaboration, including random sequence generation, allocation concealment, blinding of participants, staff and outcomes assessors, incomplete outcome data, selective outcome reporting, and other biases. In addition, the Newcastle-Ottawa Scale (NOS)
was used to evaluate risk of bias for cohort studies, items of which included selection of cohorts, comparability of cohorts, as well as assessment of outcome. The total score of the NOS scale was 9 points.
Statistical analysis
Outcomes of this meta-analysis were compression-induced injuries. I2 and P values were applied to assess the heterogeneity of the meta-analysis and the percentage of variability. This was on account of heterogeneity instead of sample error and was assessed as low, moderate, or high when I2 was <50%, 51–75%, or ≥76%, respectively. Since heterogeneity was high in compression-induced injuries, a random effects model was employed to determine the merged odds ratios (ORs) and 95% confidence intervals (CIs) for each result. Possible publication bias was evaluated through the funnel plot method and Egger’s linear regression.
A sensitivity analysis was used to test the robustness of the study model. All statistical analyses in this study were implemented via Stata 16.0 software.
Results
Screening of relevant research
Based on the retrieval strategy, 2,905 records were screened following electronic database searches and bibliographical reviews, of which 214 were duplicates. Among the remaining articles, 2,680 were eliminated on the basis of title, abstract, study design, unrelated results, unwanted comparisons, and so forth. Therefore, 11 articles were amalgamated into the present study (10 cohort studies,
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
Effects of mechanical chest compression device with a load-distributing band on post-resuscitation injuries identified by post-mortem computed tomography.
The outcomes of 2,818 cardiac arrest patients were examined in this meta-analysis, of which 1,395 patients pertained to the mechanical group [LUCAS (908 patients); AutoPulse (487 patients)] and 1423 to the manual group. Eligible studies included seven trials
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
Effects of mechanical chest compression device with a load-distributing band on post-resuscitation injuries identified by post-mortem computed tomography.
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
Effects of mechanical chest compression device with a load-distributing band on post-resuscitation injuries identified by post-mortem computed tomography.
examined the safety of chest compressions by combined means. More details of study characteristics of included articles are presented in Table 1.
Table 1Summary of the included studies
Author (year)
Country
Study design
MC/SC
Study period
Subjects
Types of mechanical devices
No. of arms (mechanical/manual)
Investigative method
Smekal (2009)
Sweden
prospective cohort study
MC
2005–2007
non-survivors of CA
LUCAS
38/47
autopsy
Pinto (2013)
America
retrospective cohort study
SC
2005–2009
non-survivors of CA
AutoPulse
88/87
autopsy
Smekal (2014)
Sweden
prospective cohort study
MC
2008–2012
non-survivors of CA
LUCAS
139/83
autopsy
Lardi (2015)
Switzerland
retrospective cohort study
SC
2011–2013
non-survivors of CA
LUCAS
26/32
autopsy
Koga (2015)
Japan
retrospective cohort study
SC
2009–2014
non-survivors of CA
AutoPulse
241/82
PMCT
Ondruschka (2018)
Germany
retrospective cohort study
SC
2011–2017
non-survivors of CA
LUCAS
113/501
autopsy
Milling (2019)
Denmark
retrospective cohort study
SC
2015–2017
OHCA
LUCAS
84/353
autopsy, diagnostic imaging, or medical records
Friberg (2019)
Sweden
Prospective cohort study
SC
2005–2013
non-survivors of CA
LUCAS
362/52
autopsy
Sonnemans (2019)
Netherlands
retrospective cohort study
SC
2012–2017
non-survivors of CA
AutoPulse
43/29
PMCT
Koster (2017)
Netherlands
RCT
SC
2008–2014
IHCA and OHCA
LUCAS, AutoPulse
115 AutoPulse/122 LUCAS/137 manual
autopsy, PMCT, or clinical follow-up
Baumeister (2015)
Switzerland
retrospective cohort study
SC
2011–2015
non-survivors of CA
LUCAS
24/20
PMCT
SC, single center; MC, multicenter; No, number; CA, cardiac arrest; OHCA, out of hospital cardiac arrest; IHCA, in hospital cardiac arrest; LUCAS, Lund University Cardiac Assist System; RCT, randomized clinical trial; PMCT, post-mortem computed tomography.
Ten of the trials included were observational cohort studies and one was an RCT. Scores of all the cohort studies were greater than or equal to six points on the basis of NOS (seeSupplementary data 2). Assessment of risk of bias for the RCT also suggested a low risk of bias (seeSupplementary figure 1).
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
reported overall compression-induced injuries rate. Compared to manual compressions, mechanical compressions were found to be associated with significantly higher rate of overall compression-induced injuries (OR, 1.29; 95% CI, 1.19–1.41; I2, 21.83%) (Fig. 2).
Fig. 2Mechanical vs. manual chest compressions, outcome: the overall compression-induced injuries (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
reported the incidence of life-threatening injuries. These revealed no significant difference between manual and mechanical compressions (OR, 5.30; 95% CI, 0.53–53.16; I2, 71.62%) (seeSupplementary figure 2).
Skeletal fractures
Sternal fractures
Rates of sternal fractures were reported in all studies included. A random effects model was created and implemented to assess pooled effects, which suggested that there was no distinct difference in the rate of sternal fractures between the mechanical compression group and the manual compression group (OR, 1.28; 95% CI, 0.92–1.78; I2, 81.85%) (Fig. 3) .
Fig. 3Mechanical vs. manual chest compressions, outcome: sternal fractures (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
A distinction of subgroups within the mechanical compression group was established, results of which indicated a noticeably higher incidence of sternal fractures in the LUCAS group than the manual group (OR, 1.63; 95% CI, 1.23–2.15; I2, 67.63%), while there were no differences between the AutoPulse and manual groups (OR, 0.69; 95% CI, 0.30–1.57; I2, 81.82%) (Fig. 4).
Fig. 4Mechanical (subgroups distinguishing LUCAS from AutoPulse) vs. manual chest compressions, outcome: sternal fractures (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
of which reported rates of rib fractures, where the mechanical device used was the LUCAS. Compared to manual compressions, the LUCAS device was shown to be associated with an increased overall risk of rib fractures (OR, 1.23; 95% CI, 1.12–1.35; I2, 22.35%), and multiple rib fractures (rib fractures ≥3) (OR, 1.45; 95% CI, 1.13–1.87; I2, 62.36%). In contrast, no significant differences in the rate of rib fractures <3 were found (OR, 0.97; 95% CI, 0.26–3.61; I2, 35.56%) (Fig. 5).
Fig. 5Mechanical (LUCAS) vs. manual chest compressions, outcome: rib fractures, rib fractures ≥3, rib fractures <3 (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Effects of mechanical chest compression device with a load-distributing band on post-resuscitation injuries identified by post-mortem computed tomography.
investigated the location of rib fractures, and mechanical CPR was found to correlate with a significantly higher risk of posterior rib fractures than manual compressions (OR, 7.28; 95% CI, 2.47–21.49; I2,37.96%) (seeSupplementary figure 3). When subgroup analysis was performed, the above differences in posterior rib fractures remained when comparing AutoPulse with manual compressions (OR, 9.94; 95% CI, 2.02–48.86; I2, 67.85%), while no significant discrepancies between AutoPulse and manual CPR were found with regard to anterolateral rib fractures (OR, 1.05; 95% CI, 0.94–1.17; I2, 0.00%) (seeSupplementary figure 4).
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
of the studies included examined the rate of vertebral fractures and found no differences between mechanical and manual methods (OR, 3.82; 95% CI, 0.85–17.19; I2, 0.00%). When subgroup analysis was performed, the results did not change (seeSupplementary figure 5).
among the studies included analyzed total visceral injuries. No differences between mechanical and manual groups were found (OR, 3.04; 95% CI, 0.41–22.54; I2, 85.33%) (seeSupplementary figure 6).
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
Effects of mechanical chest compression device with a load-distributing band on post-resuscitation injuries identified by post-mortem computed tomography.
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
Effects of mechanical chest compression device with a load-distributing band on post-resuscitation injuries identified by post-mortem computed tomography.
AutoPulse vs. manual compressions). Mechanical methods were found to be associated with a higher risk of heart lesions (OR, 2.10; 95% CI, 1.25–3.55; I2, 40.96%). When subgroup analysis was performed, a significantly higher rate of heart lesions was identified in the LUCAS group compared to manual CPR group (OR, 2.17; 95% CI, 1.07–4.39; I2, 57.31%). In contrast, no noteworthy discrepancies were identified between the AutoPulse and manual compression groups (OR, 2.08; 95% CI, 0.81–5.36; I2, 0.00%) (Fig. 6).
Fig. 6Mechanical vs. manual chest compressions, outcome: heart lesions (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
evaluated LUCAS vs. AutoPulse vs. manual compressions). No differences were apparent between mechanical and manual methods (OR, 1.94; 95% CI, 0.83–4.56; I2, 68.94%) (Fig. 7). When subgroup analysis was performed between LUCAS and manual compressions, the result did not change (OR, 1.91; 95% CI, 0.80–4.56; I2, 69.30%) (seeSupplementary figure 7).
Fig. 7Mechanical vs. manual chest compressions, outcome: lung lesions (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
was a three-way comparison between LUCAS vs. AutoPulse vs. manual CPR). Compared to manual CPR, mechanical compressions were found to be associated with a higher risk of liver lesions (OR, 2.75; 95% CI, 1.22–6.20; I2, 44.92%) (Fig. 8).
Fig. 8Mechanical vs. manual chest compressions, outcome: liver lesions (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
When the subgroup distinguishing LUCAS and AutoPulse within the mechanical compression group was conducted, a significantly higher rate of liver lesions was identified in LUCAS than manual CPR (OR, 4.10; 95% CI, 2.27–7.40; I2, 0.0%), while no notable discrepancies were detected between the AutoPulse and manual compression groups (OR, 0.80; 95% CI, 0.16–4.07; I2, 19.02%) (seeSupplementary figure 8).
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
AutoPulse vs. manual). No differences were identified in the rate of either spleen (OR, 1.06; 95% CI, 0.13–8.63; I2, 67.28%) or kidney and perirenal lesions (OR, 3.09; 95% CI, 0.72–13.36; I2, 0.0%) between the mechanical and manual groups (seeSupplementary figure 9). When subgroup analysis was performed between LUCAS and manual compressions, neither result changed (OR, 2.24; 95% CI, 0.17–30.05; I2, 53.93%; OR, 3.46; 95% CI, 0.66–18.05; I2, 0.15%, respectively) (seeSupplementary figure 10).
Lesions to major vessels
The rate of injuries to major vessels was reported in four
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
of the studies included, each of which used LUCAS. LUCAS compressions were found to be linked to an increased risk of injury to major vessels compared to manual compressions (OR, 2.93; 95% CI, 1.01–8.46; I2, 0.0%) (seeSupplementary figure 11).
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
Effects of mechanical chest compression device with a load-distributing band on post-resuscitation injuries identified by post-mortem computed tomography.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
Effects of mechanical chest compression device with a load-distributing band on post-resuscitation injuries identified by post-mortem computed tomography.
evaluated LUCAS vs. AutoPulse vs. manual compressions). Mechanical CPR was shown to be associated with a higher risk of pneumothorax than manual compressions (OR, 2.05; 95% CI, 1.19–3.54; I2, 21.1%) (seeSupplementary figure 12).
When the subgroups distinguishing LUCAS and AutoPulse within the mechanical compression group were analyzed, a significantly higher rate of pneumothorax was found in the AutoPulse group compared to manual CPR (OR, 2.25; 95% CI, 1.17–4.31; I2, 0.00%), while no notable discrepancies were identified between LUCAS and manual compressions (OR, 1.64; 95% CI, 0.72–3.76; I2, 39.73%) (seeSupplementary figure 13).
Other injuries
Some trials also identified other compression-induced injuries, where mechanical methods were found to be linked to a higher risk of hemoperitoneum (OR, 3.97; 95% CI, 1.76–8.99; I2, 0.00%) and skin lesions than manual compressions (OR, 3.53; 95% CI, 2.34–5.33; I2, 58.79%), while no statistical discrepancies in rates of haemothorax or retrosternal bleeding were identified (seeSupplementary figure 14).
When subgroup analysis was performed between LUCAS and manual modalities, a significantly higher risk was identified in the former than the latter in: haemothorax (OR, 3.62; 95% CI, 1.92–6.83; I2, 0.00%), hemoperitoneum (OR, 5.44; 95% CI, 1.31–22.55; I2, 0.00%) and skin lesions (OR, 3.80; 95% CI, 1.87–7.70; I2, 56.85%), while no notable discrepancies in rates of retrosternal bleeding or mediastinal bleeding were detected between the groups (seeSupplementary figure 15).
Sensitivity analysis
Since none of the 11 studies were assessed as high risk of bias, no sensitivity analysis was implemented in accordance with the methodological criteria. As an alternative, sensitivity analysis was implemented through the means of eliminating the included articles one by one to evaluate their impact on the pooled OR and 95% CI. The figures obtained showed that the results were stable and credible (Supplementary figure 16 and Supplementary figure 16– Sensitivity analysis for sternal fractures and for lung injuries, respectively).
Publication bias
Funnel plots (Fig. 9) and Egger’s regression asymmetry tests were performed to evaluate the possible publication bias in the included studies. Evaluating the sternal fractures between mechanical and manual chest compressions suggested that no significant publication bias was found (P = 0.512).
In this meta-analysis, 11 trials analyzing compression-induced injuries and involving 2,818 patients were analyzed. The results of this study suggest that mechanical compressions comprised a significantly higher rate of overall compression-induced injuries than manual compressions. However, no notable discrepancies were identified between the two groups regarding rate of life-threatening injuries. When considering specific bone or visceral damage, manual compressions were shown to present a lesser risk of posterior rib fractures, heart lesions, liver lesions, and pneumothorax compared to mechanical CPR. In contrast, both compression methods shared similar rates of sternal and vertebral fractures, lung, spleen, and kidney lesions, and haemothorax. However, a discrepancy between the damage distribution associated with LUCAS compared to AutoPulse was identified. Compared to manual compressions, LUCAS was shown to present higher risks of skeletal and visceral injuries, including sternal and rib fractures, heart lesions, liver lesions, major vessel injuries, and haemothorax. In addition, significant differences were noted in terms of posterior rib fractures and pneumothorax when comparing AutoPulse with manual CPR.
A concise meta-analysis conducted by Bonnes et al.
had found no difference in respect of injuries associated with CPR when comparing mechanical and manual compressions, which findings were not consistent with the present authors’ study. Possible reasons for the above discrepancy results may include the following: (1) all the studies included in the meta-analysis
Mechanical chest compressions and simultaneous defibrillation vs conventional cardiopulmonary resuscitation in out-of-hospital cardiac arrest: the LINC randomized trial.
which had focused more on efficacy than safety, leading to the possibility that compression-induced injuries had been underestimated. However, the primary outcome of all eligible studies in the present meta-analysis was safety, which may have provided greater scientific evidence for the safety of chest compressions. (2) The research methods into injuries in the previous studies
Mechanical chest compressions and simultaneous defibrillation vs conventional cardiopulmonary resuscitation in out-of-hospital cardiac arrest: the LINC randomized trial.
had primarily been based on reviewing clinical records, whereas the trials included in the present meta-analysis used autopsy and PMCT. More importantly, it is widely acknowledged that forensic autopsy remains the gold standard for detecting and evaluating injuries
Effects of mechanical chest compression device with a load-distributing band on post-resuscitation injuries identified by post-mortem computed tomography.
The effectiveness of postmortem multidetector computed tomography in the detection of fatal findings related to cause of non-traumatic death in the emergency department.
Therefore, this present meta-analysis may be more adequately to evaluate the safety of mechanical and manual chest compressions.
The present study revealed a higher incidence in overall compression-induced injuries, rib fractures, heart and liver lesions, pneumothorax, and hemoperitoneum in mechanical than in manual compression methods. According to the present authors, this may be due to (1) mechanical devices becoming displaced during use and applying excessive force to vulnerable thoracic or abdominal structures, leading to increased rates of fractures and organ damage;
(2) mechanical devices being deemed likely to exert more forceful pressure at a standard frequency and depth than manual CPR, which may have multiplied the incidence of injuries;
device displacement during use, and transition from manual to mechanical chest compressions were cited as key causes of time loss. Thus, prolonged CPR administration when using mechanical devices may have compounded injury occurrences. Interestingly, although mechanical chest compressions were found to be associated with an increased risk of overall compression-induced injuries, no such correlation was observed when comparing the incidence of life-threatening injuries between manual and mechanical compressions. However, only three studies had reported this index, which comprised differences in their respective standard setting of life-threatening injuries, and a relatively large heterogeneity, so further studies would be needed to verify this outcome.
In addition, in the subgroup analysis, the present study showed that LUCAS and AutoPulse CPR caused different patterns of fractures and visceral injuries. This may be due to the distinct respective mechanisms of the two devices: the LUCAS device focuses its compressive force on the sternum, consequently leading in particular to sternal fractures, heart lesions, haemothorax; whereas the mechanism of the AutoPulse
appliance instead exerts pressure to a broader chest area by tightening the LDB to supply a constant reduction of 20% in the anterior–posterior dimension, which may apply significant stress to the posterior ribs and generate elevated intra-thoracic pressure, potentially increasing the rate of posterior rib fractures and pneumothorax. Hence the two devices may present distinct post-resuscitation damage, as is contended here.
The advantages of the present study include: (1) this was a meta-analysis to investigate compression-induced injuries by comparing mechanical with manual chest compression methods in patients post-cardiac arrest, thus setting out a preliminary map of the injury locations for physicians. This in turn could be used for reference to assist in making clinical choices and enhancing awareness and ability among emergency and cardiac medical personnel to assess fractures and visceral injuries following successful resuscitation; (2) the mechanical CPR group was split into the LUCAS and AutoPulse subgroups in order better to understand their respective characteristics; (3) though most of the trials included in the present research were observational studies, sensitivity analysis indicated that the results are stable and reliable.
This study nonetheless comprises the following limitations: first, it was a secondary analysis of original literature. There was high heterogeneity between studies regarding several outcomes, which may have been due to differences in sample size, types of mechanical devices, etc. This disparity may in turn have influenced statistical results. Second, all but one of the studies examined were observational, with just a single RCT. Data from the RCT and observational studies were combined for the purposes of statistical analysis, which may be regarded as a flaw in methodology.
Conclusion
In the authors’ view, this study provides a sound preliminary map of compression-induced injuries and suggests that manual CPR may decrease the risk of injuries compared to mechanical chest compressions. Interestingly, a similar incidence in life-threatening injuries between manual and mechanical compressions was observed, which suggests that mechanical compression methods did not increase the risk of life-threatening injuries. Additional studies are required to further understand the safety of mechanical chest devices. Therefore, mechanical chest compression devices should be employed with greater caution, and all patients with successful CPR outcomes should undergo appropriate imaging examinations to screen for any compression-induced injuries.
Conflict of interest
The authors have no conflict of interest to disclose.
Funding and acknowledgements
This research was supported by: the National Science and Technology Major Project (grant number: 2017ZX10103005-009), the National Nature Science Foundation of China (grant number: 81701893), the Joint Construction Project of Henan Province Medical Science and Technology Research Plan (grant number: SB201901006), Science and Technology people-benefit project of Zhengzhou (grant number: 2020KJHM0001), the Teaching reform research and Practice Project of Zhengzhou University (grant number: 2020zzuJXLX083), CAMS Innovation Fund for Medical Sciences (CIFMS) (grant number: 2020-I2M-C&T-B-014), Leading Talents Fund in Science and Technology Innovation in Henan Province (grant number: 194200510017), and the Key Scientific Research Projects of Institutions of Higher Learning in Henan Province (grant number: 20A320046).
Ethics approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Availability of data and materials
The datasets used and/or analyzed during the present study are available from the corresponding author upon reasonable request.
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Appendix A. Supplementary material
The following are the Supplementary data to this article:
Supplementary figure 2Mechanical vs. manual chest compressions, outcome: life-threatening injuries (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 3Mechanical vs. manual chest compressions, outcome: posterior rib fractures (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 4AutoPulse vs. manual chest compressions, outcome: anterolateral and posterior rib fractures (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 5Mechanical vs. manual chest compressions, outcome: vertebral fractures (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 6Mechanical vs. manual chest compressions, outcome: visceral injuries (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 7LUCAS vs. manual chest compressions, outcome: lung lesions (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 8Mechanical (subgroups distinguishing LUCAS from AutoPulse) vs. manual chest compressions, outcome: liver lesions (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 9Mechanical vs. manual chest compressions, outcome: lesions to spleen, kidneys and perirenal injuries (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 10LUCAS vs. manual chest compressions, outcome: lesions to spleen, kidneys and perirenal injuries (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 11Mechanical (LUCAS) vs. manual chest compressions, outcome: major vessel injuries (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 12Mechanical vs. manual chest compressions, outcome: pneumothorax (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 13Mechanical (subgroups distinguishing LUCAS from AutoPulse) vs. manual chest compressions, outcome: pneumothorax (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Supplementary figure 14Mechanical vs. manual chest compressions, outcome: other injuries (Figure legend: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur.)
Supplementary figure 15LUCAS vs. manual chest compressions, outcome: other injuries (Figure legends: “Yes” represents the number of cases in which injuries occurred, and “No” represents the number of cases in which injuries did not occur).
Part 3: Adult Basic and Advanced Life Support: 2020 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care.
Application of mechanical cardiopulmonary resuscitation devices and their value in out-of-hospital cardiac arrest: A retrospective analysis of the German Resuscitation Registry.
CPR-related injuries after manual or mechanical chest compressions with the LUCAS device: a multicentre study of victims after unsuccessful resuscitation.
Mechanical chest compression with LUCAS device does not improve clinical outcome in out-of-hospital cardiac arrest patients: A systematic review and meta-analysis.
No difference in autopsy detected injuries in cardiac arrest patients treated with manual chest compressions compared with mechanical compressions with the LUCAS device–a pilot study.
Effects of mechanical chest compression device with a load-distributing band on post-resuscitation injuries identified by post-mortem computed tomography.
The effectiveness of postmortem multidetector computed tomography in the detection of fatal findings related to cause of non-traumatic death in the emergency department.
Mechanical chest compressions and simultaneous defibrillation vs conventional cardiopulmonary resuscitation in out-of-hospital cardiac arrest: the LINC randomized trial.
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