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Resuscitation 81 (2010) 1152–1155

Contents lists available at ScienceDirect

Resuscitation

journa l homepage: www.e lsev ier .com/ locate / resusc i ta t ion

imulation and education

uality of chest compressions during continuous CPR; comparison betweenhest compression-only CPR and conventional CPR�

hika Nishiyamaa, Taku Iwamia,∗, Takashi Kawamuraa, Masahiko Andoa,aohiro Yonemotob, Atsushi Hiraidec, Hiroshi Nonogid

Department of Preventive Services, Kyoto University School of Public Health, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, JapanDepartment of Epidemiology and Biostatistics, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashimachi , Kodaira, Tokyo 187-8553, JapanCenter for Medical Education, Kyoto University Graduate School of Medicine, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, JapanDepartment of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan

r t i c l e i n f o

rticle history:eceived 28 January 2010eceived in revised form 11 April 2010ccepted 8 May 2010

eywords:asic life support (BLS)ystander CPRardiac arrestardiopulmonary resuscitation (CPR)hest compression

a b s t r a c t

Objectives: This study aimed to compare the time-dependent deterioration of chest compressionsbetween chest compression-only cardiopulmonary resuscitation (CPR) and conventional CPR.Methods: This study involved 106 and 107 participants randomly assigned to chest compression-onlyCPR training and conventional CPR training, respectively. Immediately after training, participants wereasked to perform CPR for 2 min and the quality of their CPR skills were evaluated. The number of chestcompressions in total and those with appropriate depth were counted every 20-s CPR period from the startof CPR. The primary outcome was the CPR quality index calculated as the proportion of chest compressionswith appropriate depth among total chest compressions.Results: The total number of chest compressions remained stable over time both in the chest compression-only and the conventional CPR groups. The CPR quality index, however, decreased from 86.6 ± 25.0 to

ducationanikin

andomized controlled trial

58.2 ± 36.9 in the chest compression-only CPR group from 0–20 s through 61–80 s. The reduction wasgreater than in the conventional CPR group (85.9 ± 25.5 to 74.3 ± 34.0). The difference in the CPR qualityindex reached statistical significance (p = 0.003) at 61–80 s period.Conclusions: Chest compressions with appropriate depth decreased more rapidly during chestcompression-only CPR than conventional CPR. We recommend that CPR providers change their roles

the qu

every 1 min to maintainCTR C0000000321)

. Introduction

Bystander-initiated cardiopulmonary resuscitation (CPR) playsmajor role in the chain of survival to save cardiac arrest victims.1

ecently, chest compression-only CPR without ventilations, haseen advocated as the alternative to chest compression plus rescuereathing resuscitation (conventional CPR).2–7 Chest compression-nly CPR is attractive because not only can it deliver a greaterumber of chest compressions without interruption but also it

s simpler and easier to learn and perform CPR than conven-

ional CPR.8 We demonstrated that people who attended chestompression-only CPR training programs performed better chestompressions than those who attended conventional CPR trainingrograms in a randomized controlled trial.9

� A Spanish translated version of the abstract of this article appears as Appendixn the final online version at doi:10.1016/j.resuscitation.2010.05.008.∗ Corresponding author. Tel.: +81 75 753 2401; fax: +81 75 753 2424.

E-mail address: iwamit@e-mail.jp (T. Iwami).

300-9572/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved.oi:10.1016/j.resuscitation.2010.05.008

ality of chest compressions during chest compression-only CPR. (UMIN-

© 2010 Elsevier Ireland Ltd. All rights reserved.

The quality of chest compressions has been recognized as a keydeterminant of successful CPR and the importance of continuouschest compressions with adequate depth is emphasized.1 Majorconcern is that the rescuer’s fatigue might deteriorate the qual-ity of CPR during continuous chest compressions.10,11 Some studyshowed that the quality of chest compression declines over timeduring chest compression-only CPR and conventional CPR, but inthese studies experimental conditions were insufficient.10–13 Thisstudy aimed to compare the time-dependent deterioration of chestcompressions between the two types of CPR as an additional anal-ysis in our abovementioned study.9

2. Methods

2.1. Study design and participants

This study was designed as a randomized controlled trial (RCT)and the details are shown in our previous report.9 Briefly, vol-unteers aged 18 years or more were recruited from the general

C. Nishiyama et al. / Resuscitation 81 (2010) 1152–1155 1153

Table 1Baseline characteristics of participants.

Chest compression-only CPR (n = 106) Conventional CPR (n = 107) p-value

Men, n (%) 55 (51.9) 56 (52.3) 0.528Age, year, means ± SD 38.7 ± 20.0 38.1 ± 14.5 0.780Previous CPR training, n (%) 42 (39.6) 47 (43.9) 0.309

2 (1.9) 0.3377 (6.5) 0.170

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Experience of actual CPR, n (%) 4 (3.8)Family history of sudden cardiac death, n (%) 3 (2.8)

PR denotes cardiopulmonary resuscitation.

ublic (December 2005 through July 2006) and randomly assignedo either the chest compression-only CPR group or the conven-ional CPR (30:2) group with stratification by sex and age (<40r ≥40 years) using permuted blocks. Health care professionals oredical/co-medical students were excluded from this study.A total of 223 participants were enrolled, 112 of whom under-

ent a 120-min training program consisting of continuous chestompressions and an automated external defibrillator (AED) oper-tion. The remaining 111 were given with a 180-min trainingrogram consisting of chest compressions, ventilations, and an AEDperation based on the 2005 American Heart Association guidelinesor cardiopulmonary resuscitation and emergency cardiovascularare (chest compression/ventilation ratio of 30:2). Mean age ofarticipants was 38 years, and 52% were men.

.2. Data collection

After the training and a short break, we evaluated participants’esuscitation skills using a case-based scenario. In this test, a partic-pant was called into the testing room and said: “Imagine, you aret a department store. Suddenly a man collapses in front of you. Youre the only person around. Do whatever you can do to help thisan.” We gave the same scenario for all participants and evaluated

heir CPR skills. After presentation of the scenario, we evaluatedheir CPR skills including initial assessment, calling for 119 (emer-ency call number in Japan), chest compressions, and ventilationsfor the conventional CPR group) for 2 min. The data on CPR skillsere collected automatically by use of Laerdal Resusci Anne PC

killreporting Manikin System® (Laerdal Medical, Stavanger, Nor-ay).

.3. Measure quality of chest compression

We counted the number of chest compressions in total andhose with appropriate depth during every 20-s CPR period fromhe start of CPR (i.e., start of chest compressions in the chestompression-only CPR group and either start of ventilations orhest compressions in the conventional CPR group). The primaryutcome of this analysis was CPR quality index calculated as theroportion of chest compressions with appropriate depth amonghe total chest compressions during every 20-s CPR period. Theppropriate depth was defined as 3.5–5.5 cm according to theapanese CPR guideline.14 We also evaluated the number of chestompressions, time to CPR, and no-flow time.

.4. Statistical methods

Analyses were performed on an intention-to-treat basis. The

ata were compared across groups using chi-square test for cat-gorical variables and Student’s t-test for continuous variables.nalyses were performed using SPSS Ver.12 (SPSS, Inc., Chicago,

L). A two-tailed value of p < 0.05 was considered statistically sig-ificant.

Fig. 1. Number of chest compressions during every 20-s CPR period of chestcompression-only CPR and conventional CPR. Error bar indicates standard deviation.

2.5. Ethical considerations

All procedures were conducted according to the Declaration ofHelsinki. Participants submitted written informed consent prior toparticipation. This study was approved by the Ethics committees ofKyoto University Graduate School of Medicine.

3. Results

3.1. Baseline characteristics

In this RCT, 6 participants assigned to the chest compression-only CPR group and 4 to the conventional CPR group were absentfrom training because of urgent business or poor physical con-dition. Therefore, the remaining 106 participants in the chestcompression-only CPR group and 107 participants in the con-ventional CPR group were evaluated for their CPR skills. Baselinecharacteristics of the two groups are shown in Table 1. There wereno significant differences in age, sex ratio, previous CPR training,experience of actual CPR, and family history of sudden cardiac arrestbetween the groups.

3.2. Decline in quality of chest compressions over time

Fig. 1 illustrates the time-course of the number of chest com-pressions. The numbers were 34.1 ± 4.2, 35.1 ± 4.7, 35.1 ± 4.7 and35.6 ± 5.1 in the chest compression-only CPR group and 17.7 ± 6.7,17.5 ± 4.7, 24.0 ± 6.2 and 20.2 ± 7.9 in the conventional CPR groupduring 0–20, 21–40, 41–60 and 61–80 s, respectively. The numbersof chest compressions remained stable in both groups, but theywere greater in the chest compression-only CPR group than in the

conventional CPR group at any CPR period.

Fig. 2 shows the chronological change in the quality of CPR.The quality index gradually decreased from 86.6 ± 25.0 (0–20 s) to58.2 ± 36.9 (61–80 s) in the chest compression-only CPR group andfrom 85.9 ± 25.5 (0–20 s) to 74.3 ± 34.0 (61–80 s) in the conven-

1154 C. Nishiyama et al. / Resuscitati

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ig. 2. CPR quality index, the proportion of chest compressions with appropri-te depth among the total chest compressions during 20-s CPR period, for chestompression-only CPR and conventional CPR. Error bar indicates standard deviation.

ional CPR group over time. The decay of CPR was greater duringhe chest compression-only CPR, and the intergroup difference inhe CPR quality index increased, reaching statistical significance at1–80 s period (p = 0.003).

.3. Interruption of chest compressions during 2-min CPR

Time to the first resuscitation (either chest compressionr ventilation) was 32.0 ± 8.0 s and 35.0 ± 9.0 s in the chestompression-only CPR group and in the conventional CPRroup, respectively (p = 0.005). No-flow time was 32.0 ± 9.0 s and1.0 ± 10.0 s in the chest compression-only CPR group and the con-entional CPR group, respectively (p < 0.001).

. Discussion

To our knowledge, this is the first RCT indicating a difference inhe time-dependent deterioration of chest compressions betweenhest compression-only CPR and conventional CPR with compres-ion/ventilation ratio of 30:2. It demonstrated that the quality ofhest compressions declined more rapidly in chest compression-nly CPR than in conventional CPR and the difference reachedtatistical significance 1 min after start of CPR. Previous studiesvaluating the influence of rescuer fatigue on the quality of chestompressions had some weak points including the non-controlledtudy design, biased participants such as medical students,12 ando CPR training before skills evaluation.13 In the latter study, it

s not clear whether their fatigue or lack of CPR knowledge skillsindered their CPR performance, because their CPR were evalu-ted without prior CPR training. In addition, they compared chestompression-only CPR with the conventional CPR with compres-ion/ventilation ratio of 15:2.12 Hence, our study provided validnd updated evidence on the time-dependent CPR deterioration.

Although the number of total chest compressions did not changever time, the percentage of correct compressions with sufficientepth was gradually reduced with ongoing resuscitation as pre-iously reported.12,15,16 Most plausible explanation of this qualityeterioration is the cumulative fatigue resulting from continuous

1,10,11,15

hest compressions. One clinical study evaluating actualn-hospital resuscitation also found time-dependent deteriorationf chest compression by rescuer’s fatigue.17 This inference waslready confirmed by some studies using physiological markersuch as heart rate, oxygen saturation by pulse oximetry, blood

on 81 (2010) 1152–1155

lactate concentration, and neuromuscular function.18–21 In thesereports, physical fitness may be beneficial to CPR providers toensure the adequacy of chest compressions during CPR.10,16,18–21 Inthe conventional CPR, longer hands-off time caused by ventilationsmight serve as a rest and result in a recovery from fatigue.

The 2005 American Heart Association guidelines for CPR andemergency cardiovascular care recommend that rescuers changetheir chest compressions every 2 min during conventional CPR,1

but it does not refer to a change during chest compression-only CPR due to insufficient evidence. Rescuers generally do notbecome aware when their fatigue-induced compression impair-ment begins.11 Unless the rescuer complains of fatigue, he/sheshould be replaced with others in order to maintain the qualityof chest compressions. According to the findings of this study, werecommend that rescuers should change their roles in CPR every1 min for chest compression-only CPR.

Even if chest compression-only CPR has the drawback of easyfatigability, much larger numbers of chest compressions during 2-min CPR than the conventional CPR8,9 would amply compensatefor this weakness. It is simpler, easier to learn and perform8,9 andis expected to increase the number of lay people who could per-form bystander-initiated CPR.9,22 Bearing these features in mind,we should disseminate chest compression-only CPR in order toincrease bystander CPR and improve survival after OHCA.

This study has some limitations. First, we did not measure theintermediate factors that lowered the quality of CPR and could notthoroughly infer the biological mechanism of chest compressiondecay. Second, the resuscitation skills were evaluated by a case-based scenario test and actual resuscitation performances wereunknown. Third, although rescuers’ characteristics such as gen-der, height, and weight also would influence the quality of chestcompressions,10 we did not evaluate these factors in this study. Weare planning to assess the associations between rescuers’ charac-teristics and CPR quality in the next study. Finally, we cannot ruleout the possibility that the difference in duration of CPR trainingmight affect the outcomes.”

5. Conclusions

Quality of chest compressions rapidly declined in the chestcompression-only CPR compared with the conventional CPR. Werecommend that rescuers should change their roles in CPR every1 min to maintain the quality of chest compressions during chestcompression-only CPR.

Conflict of interest statement

There are no conflicts of interest to declare.

Role of funding source

This study was supported by a Grant-in-Aid for Health andLabour Sciences Research Grants (H16-Shinkin-02) from theJapanese Ministry of Health, Labour and Welfare.

Acknowledgements

We gratefully acknowledge Masaaki Matsumoto, KatsuharuHirai, Shohei Nakai, Keiji Akatsuka, Tatsuo Azuma, Katsuo Ogura,Eiji Ohtani, Nobuyuki Iwai, Masato Ando, Kazushi Nakajima,

Yasuyuki Shinkai, Katsuya Ito, Seiji Kasatani, and Rei Suzuki forinstruction in the CPR training program. We also thank all membersof the Japanese Population-based Utstein-style Study with Basicand Advanced Life Support Education (J-PULSE), and the faculty ofKyoto University School of Public Health for helpful comments on

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he design and data analyses, both of which were critical to theuccessful study.

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