In Pre-Hospital Cardiac Arrest Patients, How Does Hands-Only CPR Compared To Standard CPR, Affect Neurological Outcomes?

Abstract
Summary
Out-of-hospital cardiac arrest is the leading cause of death in the U.S. Increasing bystander-initiated CPR through “hands-only” CPR and EMS dispatcher instructed “hands-only” CPR improves survival rates.
Methods
CINAHL, PubMed, and OvidMD were searched for the following key terms or combination thereof: “hands-only”; “compression-only”; chest compression-only”; “bystander”; “CPR”; “dispatcher”; and “neurological affect”. We initially restricted our search to peer-reviewed studies published in English between January 2004 and June 2014, but agreed by consensus to use a 2000 study located during a manual search of included study references.
Results
We identified nine Level II, III, and IV studies comparing “hands-only” CPR and “standard” CPR, published between 2000 and 2013, and occurring in the countries of Japan, London, Sweden and the U.S. All but one of the study results recommend that “hands-only” CPR is at least equal or superior to “standard” CPR.
Conclusions
Guidelines should be established to teach bystander “hands-only” CPR nationwide, to increase public awareness of the effectiveness of “hands-only” CPR and start to teach out-of-hospital “hands-only” CPR.

Introduction
Sudden cardiac arrest is the leading cause of death in the United States (Neumar, Barnhart, Berg, Chan, Geocadin, Luepker,… Nichol, 2011). According to the American Heart Association (AHA), “Each year, emergency medical services (EMS) assesses nearly 360,000 out-of-hospital cardiac arrests (OHCA) in the United States” (Neumar, et al. 2011). Bystander initiated cardiopulmonary resuscitation (CPR) could mean the difference between life and death in many of these victims. The 2008 AHA Science Advisory Committee for the Public approved the use of “hands-only” CPR (HO-CPR) in a collapsed adult victim of sudden cardiac arrest (Sayre, Berg, Cave, Page, Potts, & White, 2008). The purpose of the recommendation is to increase bystander involvement and improve victim survival outcomes. The current 2010 AHA guidelines for bystander or dispatcher assisted CPR involves two simple steps: 1) call 9-1-1 (or send someone to do that), and; 2) push hard and fast in the center of the chest (Sayre, et al. 2008). This Committee has concluded that adult victims of OHCA who received bystander HO-CPR or standard CPR have a similar chance of survival (Sayre, et al. 2008). Our PICO question is: In pre-hospital cardiac arrest patients how does “hands-only” CPR (HO-CPR) compared to “standard” CPR (STD-CPR) affect neurological outcomes? The importance of bystander CPR is a crucial piece in the links in the chain of survival: early recognition, activation of the emergency response system, and initiation of CPR in an out-of-hospital cardiac arrest victim (Sayre, et al. 2008). Two of the members of our group are affiliated with the AHA as instructors and have a special interest in promoting bystander CPR as the first link in the chain of survival and to improve outcomes. The review of literature will illustrate the importance of “hands only” CPR and its clinical impact on out-of-hospital adult cardiac arrest victims.
Methods
In this mini-systematic review, our group convened and selected three electronic medical databases and agreed upon key terms to be searched. Due to restrictions in scope and time, this mini review was not a comprehensive search of available databases or publications, rather our group agreed upon electronic search of the three most widely used databases from our combined collegiate experience: CINAHL, PubMed, and OvidMD. The key terms we agreed upon to search included any combination of the following: “hands-only”; “compression-only”; chest compression-only”; “bystander”; “CPR”; “dispatcher”; and “neurological affect”. In order to develop this paper in the most efficient manner with up-to-date data, we initially restricted our search to peer-reviewed studies published in English between January 2004 and June 2014.
After independently performing our searches, we reconvened our group to analyze our search results that identified eight potential studies. We then conducted a manual check of each study’s reference list to further identify any potential studies. During this manual check, we identified one additional study that was published in the year 2000, but after a group discussion and consensus, we included that study in our review. The inclusion criteria for the selected studies were comparisons between “standard” CPR and “hands-only” (compression-only) CPR, where neurological outcomes were assessed. By the end of this group meeting, we had limited our search to nine (between 8 and 10 studies) studies, including eight of the most recent studies meeting the inclusion criteria and the one study published in 2000. Exclusion criteria was any duplicate publication and any study with no outcome data.
Results
We identified nine studies relevant to our question, including: two retrospective studies, one of which combined two randomized trials; four randomized trials, one of which was blind; two prospective observational studies; and, one animal (swine) study. The primary countries of study were Japan, England, Sweden and the United States, which were published 2000 – 2013. Among the various studies, over 23,000 out-of-hospital cardiac arrests were analyzed: Bohm, Rosenqvist, Herlitz, Hollenberg, & Svensson, (2007) 11,275 participants aged 45 to 81; Dumas, Rea, Fahrenbruch, Rosenqvist, Faxen, Svensson,… Bohm, (2013) 2946 participants over the age of 18 years; Ewy, Zuercher, Hilwig, Sanders, Berg, Otto,… Kern, (2007) 64 healthy swine; Hallstrom, Cobb, Johnson & Copass, (2000) 520 participants with the mean age of 68 years; Iwami, Kawamura, Hiraide, Berg, Hayashi, Nishiuchi,… Nonogi, (2007) 1327 participants over the age of 18 years; Nishiyama, Iwami, Kawamura, Ando, Yonemoto, Hiraide, & Nonogi, (2010) 223 participants over the age of 18 years; Rea, Fahrenbruch, Culley, Donohoe, Hambly, Innes… Eisenberg, (2010) 1942 participants with the mean age of 63 years; SOS-KANTO Study Group 4068 participants between 55 and 80 years; Svensson, Bohm, Castren, Petterson, Engerstrom, Herlitz, & Rosenqvist, (2010) 1276 participants with a mean age of 67 years. The quality of all the studies were high, six Level II studies, one Level III study and two Level IV studies.
Table 1.
Study Summary Table. Author(s) | Method/Design | Sample/Age Range | Setting | Key Findings | Major Limitations | Bohm, et al. (2007) | Retrospective cohort | 11,275 participants/ 45 to 81 years | Sweden | There was no significant difference in the 30-day survival rates between standard CPR and compression-only CPR. | - Unable to adjust for unknown variables such as comorbidities |

Table 1 (continued).
Study Summary Table. Author(s) | Method/Design | Sample/Age Range | Setting | Key Findings | Major Limitations | Dumas, et al. (2013). | Retrospective cohort, combined 2 Randomized trials | 2946 participants/ 18 years or older | DART (USA) &TANGO trials (Sweden) | There is long-term mortality benefit of dispatcher instruction strategy consisting of compression-only CPR versus standard CPR among adult patients experiencing out-of-hospital cardiac arrest and requiring dispatcher assistance. | - Conduction of original studies independently without consideration of long-term outcome.- Not including functional status or quality of live during long-term follow-up- Limited power to evaluate for subgroup or phase-specific intervention differences in the outcome. | Ewy, et al. (2007) | Randomized trial, Swine Model | 64 swine | Tuscon, AZ | The odds of neurologically normal 24-hour postresuscitation survival was significantly greater (odds ratio 3.7) for the continuous chest compression group compared to the 30:2 CPR group. | - May not apply to two person bystander CPR 30:2 when interruptions are limited.- Subject to compression depth bias.- Study was completed with an endotracheal tube in place, improving passive gas exchange. |
Table 1 (continued).
Study Summary Table. Author(s) | Method/Design | Sample/Age Range | Setting | Key Findings | Major Limitations | Hallstrom, Cobb, Johnson, Copass, (2000). | Randomized trial, Blind study | 520 participants/ mean age 68 years | Seattle, WA | The outcome of compression-only CPR is similar to that after standard CPR. Compression-only CPR may be the preferred approach for bystanders inexperienced in CPR. | - Did not follow a strict intention-to-treat analysis- No establishment of the true worth of providing CPR instructions before the arrival of emergency medical services | Iwami, et al. (2007). | Prospective, Observational study | 1327 participants/ over 18 years | Japan | The 1-year survival outcome of compression only CPR(4.3%) is slighter higher than standard CPR(4.1%) compared to no bystanders CPR. | - Lack of data on the quality of bystander CPR- Not proper training for cardiac-only resuscitation in Japan. |

Table 1 (continued).
Study Summary Table. Author(s) | Method/Design | Sample/Age Range | Setting | Key Findings | Major Limitations | Nishiyama, et al. (2010). | Randomized trial | 223 participants/ over 18 years | Japan | Chest compressions with appropriate depth decreased more rapidly during chest compression-only CPR than conventional CPR. | - No measurement of the intermediate factors that lowered the quality of CPR - No evaluation of the resuscitation skills actual resuscitation performances but by a case-based scenario.- No evaluation or consideration of rescuers’ characteristics such as gender, height, and weight. | Rea, et al. (2010). | Randomized trial | 1942 participants/ mean age 63 years | King County (WA) EMS, Thurston County (WA) EMS and London Ambulance Service (England) | The dispatcher CPR instruction consisting of chest compression alone did not increase survival when compared with chest compression plus rescue breathing overall. | - Not being able to measure the core components of the resuscitation maneuver (e.g., depth of chest compression).- Small sample |

Table 1 (continued).
Study Summary Table. Author(s) | Method/Design | Sample/Age Range | Setting | Key Findings | Major Limitations | SOS-KANTO Study Group (2007) | Prospective, Observationalstudy | 4068 participants/55 – 80 years | Kanto, Japan | Compression-only CPR is equal to or superior to standard CPR in adult patients with witnessed out-of-hospital cardiac arrest, in terms of neurological benefit.No evidence of any benefit to mouth-to-mouth ventilation in bystander CPR. | - Neither randomized control or population-based study.- Quality of bystander CPR was not assessed.- Unable to standardize postresuscitation care. | Svensson, et al. (2010). | Randomized trial | 1276 patients/ mean age 67 years | Sweden | Giving instructions for compression-only CPR before the arrival of EMS personnel does not significantly improve the outcome of patients as compared with standard CPR. Neither the one-day nor 30-day rates of survival differed significantly between the two groups | - Small randomized study sample- Protocol violation due to the prejudice of dispatchers against compression-only CPR and a preference for standard CPR- Not including the latest guideline of the AHA and the European Resuscitation Council. |

Discussion
Appraisal
With regard to the overall quality of the selected studies, 6 of the 9 studies are randomized controlled trials, one of which is a blind study. Eight of the research articles were funded by their respective institutions, government agencies or through private funding and donations. The similarity in all the research studies was that consent from the patients was not sought or obtained prior to the study, but was sometimes acquired later. The general weakness of all the studies is that they did not clearly identify the threats to validity. In the Swedish study by Bohm et al. (2007), 11,275 patients who had an out-of-hospital cardiac arrest and received bystander CPR that was reported to the Swedish Cardiac Arrest Register between 1990 and 2005 were included. EMS personnel witnessed cardiac arrests were excluded from the study (Bohm, et al. 2007). After exclusions, 8209 patients (73%) received standard CPR, 1145 patients (10%) received compression-only CPR and 1921 patients (17%) received ventilation-only CPR (Bohm, et al. 2007). When the authors compared compression-only CPR and standard CPR and adjusted for differences at baseline, survival to 1-month odds ratio was 1.18 (95% CI, 0.89 to 1.56) (Bohm, et al. 2007). The authors concluded that there was no significant differences between the two types of CPR (Bohm, et al. 2007).
In Dumas et al. (2013), the study has the advantage in study design with specific subject eligibility. Subjects were eligible for the DART study if they were unconscious and not breathing normally, bystander CPR was not ongoing, and the bystander was willing to receive instruction. In the TANGO study, subjects were eligible if the collapse was witnessed (seen or heard), and the subject was unconscious and not breathing normally (Dumas, et al. 2013). Then, the researchers performed subgroup analyses defined by arrest pathogenesis, presenting arrest rhythm, witnessed status, and emergency medical services response interval among witnessed arrests (Dumas, et al. 2013). There are no significant biases that can threaten the validity of the study because common entry criteria and the randomization approach help protect against bias and enable combination of the study data (Dumas, et al. 2013). Each study used national and provincial death registries to ascertain mortality (Dumas, et al. 2013). The authors concluded that the findings provide strong support for long-term mortality benefit of dispatcher CPR instruction strategy consisting of compression-only CPR rather than standard CPR among adult patients with cardiac arrest requiring dispatcher assistance (Dumas, et al. 2013).
We included the Ewy, et al. (2007) randomized control swine model animal study because it was a realistic experiment and directly related to our PICO question. The authors of this University of Arizona research, medically induced ventricular fibrillation in 64 otherwise healthy swine and randomly initiated either compression-only CPR or standard CPR in one of four interval groups; 3 min, 4 min, 5 min, and 6 min respectively (Ewy, et al. 2007). During the experiment, researchers continuously collected data on the aortic pressure, right atrial pressure, tidal volume, ECG, and Peak end-tidal CO2 (Ewy, et al. 2007). The first biphasic defibrillator shock was delivered the 12 min point, and followed with the initiation of advanced cardiac life support (ACLS) per the 2005 guidelines (Ewy, et al. 2007). The researchers reported that the compression-only CPR groups had a significantly higher rate of a perfusing rhythm following the initial shock (21/33) than the standard CPR groups (9/31) (Ewy, et al. 2007). After analysis of the findings, the authors of this study conclude that compression-only CPR resulted in more 24-hour neurologically normal survivors than standard CPR survivors (Ewy, et al. 2007).
Hallstorm, Cobb, Johnson, & Copass (2000) concluded that a strategy of dispatcher-instructed standard CPR was no better than a strategy of dispatcher-instructed compression-only in Seattle, WA, where there is a two-tier EMS system with relatively short response times and a tightly-structured dispatch protocol. Although the differences were not statistically significant, the rates of survival to hospital discharge were higher with compression-only CPR than standard CPR (29% higher), as was the hospital admission rate (15% higher) (Hallstorm, Cobb, Johnson, & Copass, 2000). The strength of the study can be that the research was conducted due to perceived biases in previous research as noted by the authors:
“In 1989 we therefore began a preliminary trial of dispatcher-instructed bystander CPR that compared the value of instructions for chest compression only with that of standard instructions for chest compression plus mouth-to-mouth ventilation. After approximately 200 victims had been enrolled, the study was terminated because the conditional power of rejecting the null hypothesis (i.e., that chest compression and chest compression plus mouth-to-mouth ventilation result in similar rates of survival to hospital discharge) in favor of superiority of chest compression plus mouth-to-mouth ventilation was low” (Hallstorm, Cobb, Johnson, & Copass, 2000, p. 1546).
In Iwami et al. (2007), the data from a large-scale population-based cohort in Osaka indicates that cardiac-only resuscitation and standard CPR as provided by citizens are similarly effective for most adult out-of-hospital cardiac arrests of presumed cardiac origin. The data was collected using an Utstein-style reposting guideline for cardiac arrests such as, sex, age, initial cardiac rhythm, time, course of resuscitation, type of bystander-initiated CPR, return of spontaneous circulation, and hospital admission, the 1-week, 1-month, and 1 year survival rates and neurological status 1 year after the event (Iwami et al., 2007). The study does have a few biases and weakness, like all multisite epidemiological studies, with data integrity, validity, and ascertainment bias. We also considered bias from a cultural aspect, because potential lay rescuers, EMS personnel, and medical personnel generally claim that they would be more willing to provide CPR if mouth-to-mouth rescue breathing were not necessary (Iwami et al., 2007). Willingness to perform mouth-to-mouth rescue breathing appears to differ among different cultures. In a Japanese study, only 2% of high school students, 3% of teachers and nurses, and 16% of medical students claimed that they were willing to provide mouth-to-mouth resuscitation for a stranger in cardiac arrest (Iwami et al., 2007). Nearly 40% of rescuers who provided bystander CPR did not provide mouth-to-mouth resuscitation (Iwami et al., 2007). The researchers strengthened their study by using uniform data collection, consistent definitions, time synchronization process, and large sample size to minimize these potential sources of bias (Iwami et al., 2007).
Nishiyama et al. (2010) recommend that rescuers should change their roles in CPR every one minute to maintain the quality of chest compressions during chest compression-only CPR because the quality of chest compressions rapidly declined in the chest compression-only CPR compared with standard CPR in respect to effective outcomes for patients. The most plausible explanation of this quality deterioration is the cumulative fatigue resulting from continuous chest compressions (Nishiyama, et al. 2010). In the conventional CPR, longer hands-off time caused by ventilations might serve as a rest and result in a recovery from fatigue (Nishiyama, et al. 2010). There were no significant biases or threats that can interfere with the validity of this study identified.
Rea et al. (2010) discussed the role of ventilations in cardiopulmonary resuscitation (CPR) performed by a layperson as uncertain. The researchers conducted a multicenter, randomized trial of dispatcher instructed CPR to bystanders to determine different outcomes between compression-only CPR and standard CPR (Rea, et al. 2010). They concluded that dispatcher instruction consisting of compression-only CPR did not increase the survival rate overall, although there was a trend toward better outcomes in key clinical subgroups (i.e. patients with a cardiac cause of arrest and patients with shockable rhythms) (Rea, et al. 2010). In our opinion, the ethical perspective for the participants is a weakness of this study. The study was approved by the appropriate review boards, but patients were enrolled without consent and survivors were later informed that they had been enrolled in a clinical investigation of CPR in King County EMS (Washington), or Thurston County EMS (Washington), or London Ambulance Service (England) (Rea, et al. 2010). The bias in this study that threatened the validity of the conclusions is that they did not observe overall neurologic status at discharge (Rea, et al. 2010). This finding would provide assurance that improved resuscitation with chest compression alone is not achieved at the cost of neurologic impairment. Indeed, there was some suggestion that the brain may derive specific benefit, given the increase in the magnitude of both the relative and absolute differences favoring compression-only CPR over standard CPR, as evident from the two contrasting outcomes, survival (16.8% and 14.7%, respectively) and survival with favorable neurologic status (14.4% and 11.5%) (Rea, et al. 2010).
In the prospective cohort multicenter observational study of the SOS-KANTO Study Group (2007), the researchers analyzed 4068 occurrences of witnessed out-of-hospital cardiac arrests in the Kanto Region of Japan. The authors compared the results of no bystander CPR (2917, 72%), bystander compression-only CPR (439, 11%) and bystander standard CPR (712, 18%) to a 30-day post cardiac arrest endpoint utilizing the Glasgow-Pittsburg (SOS-KANTO, 2007). It seems to go without saying, but the study concluded that there are better outcomes associated with any CPR attempt than when there was no CPR attempt (SOS-KANTO, 2007). The study also found that compression-only CPR produced more favorable neurological outcomes over standard CPR in the sub-groups of cardiac arrest with apnea, cardiac arrest with shockable rhythm and cardiac arrest with CPR started within the first four minutes (SOS-KANTO, 2007). There was no additional evidence in any sub-group that the addition of ventilations, standard CPR, improved neurological outcomes (SOS-KANTO, 2007). In Svensson et al. (2010), the authors compared the 30-day survival rate of 282 patients that received “compression-only” CPR with 297 patients that received “standard” CPR and results showed no significant difference to the 30-day survival rate. However, one weakness of this study is that compression-only CPR was not significantly better than standard CPR when applied to cardiac arrest caused by trauma, respiratory failure, intoxication, in children under 8 years of age, or in patients with whom bystanders performed CPR without instructions from dispatchers (Svensson, et al. 2010). Another weakness was that information for follow-up in 6.8% of the sample was not available (Svensson, et al. 2010). Biases of this study are that dispatchers were given detailed written instructions to use for compression-only CPR and standard CPR, but were permitted to diverge from the written instructions if they found it necessary (Svensson, et al. 2010). Threats to validity include, data collected from EMS records was compared to data on survival status from the national registers, but no inter-rater reliability assessment was performed. Finally, CPR guidelines were altered during the study, which gave compression-only CPR a more prominent role (Svensson, et al. 2010).
Synthesis
We believe that the all of study authors correctly interpreted and reported their findings and subsequently their individual conclusions. Although each study used a different measure for outcome, i.e. survival to hospital admission or survival one-day postresuscitation or survival to 30-day postresuscitation or survival till hospital discharge, 5 out of 9 articles found that there is hands-only CPR is equal to standard CPR but more research need to be done in order to highlight the significant difference in neurological outcomes between standard CPR and hands-only CPR. Three studies identified that compression-only CPR is clinically better than standard CPR.
Rhea et al. (2010) suggested that compression-only CPR may increase survival among certain groups of patients, those with a cardiac cause of arrest and those with ventricular fibrillation. Dumas et al. (2013) study provides strong support for long-term mortality benefit of dispatcher CPR instruction strategy consisting of compression-only CPR rather than standard CPR among adult patients cardiac arrest requiring dispatcher assistance. Ewy et.al (2007) described that the odds of neurologically normal 24-hour postresuscitation survival was significantly greater (odds ratio 3.7) for the continuous chest compression group compared to the 30:2 CPR group. Besides, the 1-year survival outcome of compression only CPR (4.3%) is slightly higher than standard CPR (4.1%) compared to no bystander CPR (Iwami, et al, 2007). Interestingly, Nishiyama et al. (2010) concluded that chest compressions with appropriate depth and rate decreased more rapidly during chest compression-only CPR than standard CPR. Therefore, hands-only CPR has a negative effect on the rescuer compared to standard CPR.
One major problem with Bohm et al. (2007) is true for many observational studies, which is how to identify and include multivariates, and how to factor the confounding factors, such as comorbidities or whether respiratory arrest led to cardiac arrest. In the letter case, standard CPR would be superior to compression-only CPR. The study by Dumas et al. (2013) has several limitations. “The original studies were conducted independently and were not originally designed to ascertain long-term outcome.
Although we observed survival differences, we were not able to ascertain functional status or quality of live during long-term follow-up, although favorable functional status has been associated with better long-term prognosis in the general population.” Some weaknesses that we noted in Ewy et al. (2007) include the swine that were used were otherwise healthy animals, there was an admitted randomization error, neurological outcomes was based on subjective opinion of a veterinarian, the study was conducted with an endotracheal tube in place that could skew the effect of CPR (Ewy, et al. 2007). On the other hand, strengths include the depth and force of chest compressions was monitored by mean arterial systolic pressure, the study was scientifically designed, and was presented in a transparent manner (Ewy, et al. 2007). Hallstorm, Cobb, Johnson, & Copass (2000) study has 2 limitations. First, they did not follow a strict intention-to-treat analysis. This was the case because data from many patients who were randomly assigned to treatment were excluded from the analysis for a priori reasons. With out-of-hospital cardiac arrest, it would not be appropriate to have dispatchers take the time to ask for information about all exclusion criteria before implementing the protocol. The exclusions are critical for two reasons. First, including data in the analysis on patients who did not have cardiac arrest would artifactually increase the survival rate, since most of these patients survived. Similarly, most patients with drug overdoses, alcohol intoxication, or carbon monoxide poisoning were resuscitated after respiratory arrest and hence were also survivors. Second, if patients who received no advanced cardiac life support (from whom CPR was withheld because it was considered futile or for some other reason) were included, the effect would be to reduce the survival rate, since all such patients died. The reasons for exclusion did not differ significantly between the treatment groups. The other limitation of this study is that the true worth of providing CPR instructions before the arrival of emergency medical services has not been established. However, the prevailing opinion at this time is that bystander-initiated CPR is a highly effective aid to resuscitation from cardiac arrest. “The 2 most important limitations of this study are the lack of data on the quality of bystander CPR and the potential biases involved in providing cardiac-only resuscitation, conventional CPR, or no bystander CPR. Moreover, the EMS providers’ first responsibility is to resuscitate the victim, not to evaluate the bystanders’ effectiveness at the time of their arrival. It is well known that the critical issues for blood flow during CPR are force of compressions, rate of compressions, and avoidance of interruptions in compressions. These technical issues are taught during standard CPR training in Japan. However, cardiac-only resuscitation is not taught. Rescuers who do not provide rescue breathing may be less well trained and may provide less effective chest compressions. If so, this may explain the discrepancy between the Utstein Osaka data and animal studies that show better outcomes with cardiac-only resuscitation than conventional CPR in models of out-of-hospital single- rescuer CPR for VF. Nevertheless, our data cannot explicitly address these potential biases” (Iwami et al. 2007, p. 2906). Nishiyama et al. (2010) discussed some limitations in the study. First, they did not measure the intermediate factors that lowered the quality of CPR and could not thoroughly infer the biological mechanism of chest compression decay. Second, the resuscitation skills were evaluated by a case- based scenario test and actual resuscitation performances were unknown.
Third, although rescuers’ characteristics such as gender, height, and weight also would influence the quality of chest compressions, they did not evaluate these factors in this study. Rhea et al. (2010) discussed their limitations as followed:
“The intervention randomized bystander CPR either to chest compressions alone or to chest compressions interspersed with rescue breathing in a ratio of 2 breaths to 15 compressions. This 2:15 ratio was the guideline specified during the first portion of the trial. One might expect that the results — and specifically the differences observed — would be attenuated if the ratio had been 2:30. Such an inference is uncertain given the incomplete understanding of the mechanisms underlying the benefit of CPR and the fixed logistic considerations of incorporating rescue breathing. We were able to assess progress through the study protocol, although we were not able to objectively and quantitatively measure the core components of the resuscitation maneuver (e.g., chest compression depth)” (p. 431).
Despite nearly 2000 eligible patients were enrolled, the study may still be criticized for having insufficient power to detect clinically important differences. For example, the study would need approximately 4200 subjects to have 80% power to demonstrate a significant difference in survival with a favorable neurologic outcome between the group treated with chest compression alone and the group treated with chest compression plus rescue breathing (14.4% and 11.5%, respectively). The SOS-KANTO Research Ethics Board approved the study and informed consent was waived, within the Japanese government guidelines (SOS-KANTO, 2007). Responding paramedics observed the bystander CPR technique, but the quality of individual compressions were not standardized or assessed (SOS-KANTO, 2007). The study was not randomized, nor population-based; however, the authors noted the population was “similar” to other large cities in Japan (SOS-KANTO, 2007). Resuscitation time events were unknown in 70% of the sample, possibly skewing the timed sub-groups data (SOS-KANTO, 2007). Despite funding for this study being provided by Laerdal Foundation of Acute Medicine and the Japanese Ministry of Health, Labor & Welfare, the authors deny any influence over their study design, data collection, data analysis, data interpretation or writing of the study (SOS-KANTO, 2007).
There are a few limitations in the study conducted by Svensson et al. (2010). There were
3809 patients were enrolled, but the final analysis included data from only one third of these patients (approximately 600 patients in each of the two groups). Thus, many patients who underwent randomization were subsequently excluded from the analysis, according to the predefined inclusion and exclusion criteria. Also, the dispatchers did not follow the randomization instructions in a small proportion of cases. The reason for this protocol violation is likely because some dispatchers had a prejudice against compression-only CPR and a preference for standard CPR. Some callers also showed a preference for a CPR technique other than that specified by randomization. Another consideration was that during the course of the study, the AHA and the European Resuscitation Council changed their CPR guidelines, giving greater emphasis to the quality and quantity of chest compressions.
In 2010, Hupfle, Selig & Nagele conducted a meta-analysis of three of the randomized trials (Hallstrom, Cobb, Johnson, & Copass, 2000; Rea, et al. 2010; Svensson, et al. 2010) that showed a “significantly increased chance of survival with chest-compression-only CPR compared with standard CPR, with an absolute increase in survival 2.4% (95% CI 0.1 – 4.9)” (p. 1554) despite their individual analysis showing only a “small benefit” in survival to discharge of compression-only CPR. In other words, when the studies were combined, the individual results of independent studies showed a significant improvement in outcomes.
Implications for Nursing Practice/Research
Although the above findings do not directly impact nursing practice because its’ focus was on out-of-hospital cardiac arrests, it does directly impact patient outcomes; and, thus indirectly impacts our nursing practice. We do recommend further research and a professionally-prepared review to establish standard guidelines to teach bystander “hands-only” CPR nationwide, to increase public awareness of the effectiveness of “hands-only” CPR and start to teach out-of-hospital “hands-only” CPR.
Conclusion
In conclusion, this mini-systematic review provides evidence to support bystander hands-only CPR, or dispatcher instructed hands-only CPR, over standard CPR in out-of-hospital cardiac arrests. Eight of the 9 studies included in this review concluded that bystander hands-only CPR was at least equal to or favored over bystander standard CPR, including dispatcher instructed, in out-of-hospital cardiac arrest. Only 1 of the 9 studies did not support hands-only CPR because from the rescuers’ perspective, it leads to rescuer fatigue more quickly, subsequently causing substandard chest compressions.
According to American Heart Association (2014), compression-only CPR is defined as: “Hands-Only CPR is CPR without mouth-to-mouth breaths. It is recommended for use by people who see a teen or adult suddenly collapse in an “out-of-hospital” setting (such as at home, at work or in a park). It consists of two easy steps:
1. Call 9-1-1 (or send someone to do that).
2. Push hard and fast in the center of the chest.”

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