Resuscitation Science. Bystander-Initiated Rescue Breathing for Out-of-Hospital Cardiac Arrests of Noncardiac Origin

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1 Resuscitation Science Bystander-Initiated Rescue Breathing for Out-of-Hospital Cardiac Arrests of Noncardiac Origin Tetsuhisa Kitamura, MD, MS; Taku Iwami, MD, PhD; Takashi Kawamura, MD, PhD; Ken Nagao, MD, PhD; Hideharu Tanaka, MD, PhD; Atsushi Hiraide, MD, PhD; for the Implementation Working Group for All-Japan Utstein Registry of the Fire and Disaster Management Agency Background Although chest compression only cardiopulmonary resuscitation (CPR) is effective for adult out-ofhospital cardiac arrest (OHCA) of cardiac origin, it remains uncertain whether bystander-initiated rescue breathing has an incremental benefit for OHCA of noncardiac origin. Methods and Results A nationwide, prospective, population-based, observational study covering the whole population of Japan and involving consecutive OHCA patients with emergency responder resuscitation attempts was conducted from January 2005 through December The primary outcome was neurologically intact 1-month survival. Multiple logistic regression analysis was used to assess the contribution of bystander-initiated CPR to better neurological outcomes. Among a total of bystander-witnessed OHCAs of noncardiac origin, 8878 (20.5%) received chest compression only CPR, and 7474 (17.3%) received conventional CPR with rescue breathing. The conventional CPR group (1.8%) had a higher rate of better neurological outcome than both the no CPR group (1.4%; odds ratio, 1.58; 95% confidence interval, 1.28 to 1.96) and the compression-only CPR group (1.5%; odds ratio, 1.32; 95% confidence interval, 1.03 to 1.69). However, the compression-only CPR group did not produce better neurological outcome than the no CPR group (odds ratio, 1.19; 95% confidence interval, 0.96 to 1.47). The number of OHCAs needed to treat with conventional CPR versus compression-only CPR to save a life with favorable neurological outcome after OHCA was 290. Conclusions This nationwide observational study indicates that rescue breathing has an incremental benefit for OHCAs of noncardiac origin, but the impact on the overall survival after OHCA was small. (Circulation. 2010;122: ) Key Words: cardiac arrest cardiopulmonary resuscitation death, sudden epidemiology Survival after out-of hospital cardiac arrest (OHCA) of noncardiac origin is generally poor. 1 6 Although bystanderinitiated cardiopulmonary resuscitation (CPR) plays a key role in saving OHCA victims in the chain of survival, the prevalence of bystander CPR is still low. 1 Clinical Perspective on p 299 Many studies have shown that chest compression only CPR is as effective as conventional CPR with rescue breathing for bystander-witnessed adult OHCA of cardiac origin Currently, it is recommended that laypersons who witness sudden adult collapse should provide continuous chest compressions without mouth-to-mouth ventilation. 11 It is reported that 20% to 40% of adult OHCAs are of noncardiac origin, most of which involve respiratory compromise such as drowning or asphyxia. 1 6 However, evidence of the effectiveness of bystander CPR for patients suffering OHCAs of noncardiac origin is scarce, 11,12 and it remains unclear whether the addition of bystanderinitiated rescue breathing would be needed in such cases. The Fire and Disaster Management Agency (FDMA) of Japan launched a prospective, nationwide, population-based cohort study of OHCA victims in January 2005 and collected bystander-witnessed OHCAs of noncardiac origin. Using this extensive database, we tested the hypothesis that bystander-initiated conventional CPR including chest compressions and rescue breathing would result in better outcomes after OHCAs of noncardiac origin compared with either no CPR or compression-only CPR. Methods Study Design and Setting The All-Japan Utstein registry of the FDMA is a large-scale, prospective, population-based registry of OHCA covering all of Japan. 13,14 This cohort enrolled all patients who suffered OHCA, were treated by emergency medical service (EMS) systems, and were transported to medical institutions from January 1, 2005, through December 31, Among them, patients with OHCAs of noncardiac origin who were 18 years of age whose collapse was Received November 27, 2009; accepted May 20, From the Kyoto University Health Service, Kyoto (T. Kitamura, T.I., T. Kawamura); Department of Cardiology, Cardiopulmonary Resuscitation and Emergency Cardiovascular Care, Surugadai Nihon University Hospital, Tokyo, Japan (K.N.); Graduate School of Sport System, Kokushikan University, Tokyo (H.T.); and Center for Medical Education, Kyoto University Graduate School of Medicine, Kyoto (A.H.), Japan. Correspondence to Taku Iwami, MD, PhD, Kyoto University Health Service, Yoshida Honmachi, Sakyo-ku, Kyoto , Japan. iwamit@ .jp 2010 American Heart Association, Inc. Circulation is available at DOI: /CIRCULATIONAHA

2 294 Circulation July 20, 2010 witnessed by bystanders were eligible for this study. The implementation working group for All-Japan Utstein registry of the FDMA designed the study protocol; the FDMA collected and managed the data; and the authors analyzed the data and wrote the manuscript. The protocol for analyses was approved by the Ethics Committee of the Kyoto University Graduate School of Medicine. Cardiac arrest was defined as the cessation of cardiac mechanical activity as confirmed by the absence of signs of circulation. 13,14 The arrests were classified into those of presumed cardiac and noncardiac origin, the latter resulting from external causes such as trauma, hanging, drowning, drug overdose, asphyxia, respiratory diseases, cerebrovascular diseases, malignant tumors, and any other noncardiac causes. These diagnoses were made by the physician in charge in collaboration with the EMS providers. EMS Systems in Japan Japan has an area of km 2, including both urban and rural communities, and its population was 127 million in There were 807 fire stations with a dispatch center in EMS is provided by the municipal governments. The free telephone emergency number is used to call for ambulance from anywhere in Japan. Life support is provided 24 hours a day by the local EMS system. When called, an ambulance is dispatched from the nearest fire station. Usually, each ambulance has a crew of 3 emergency providers, including at least 1 emergency life-saving technician, a highly trained prehospital emergency care provider. Emergency life-saving technicians are allowed to insert an intravenous line and an adjunct airway and to use semiautomated external defibrillators for OHCA patients. Specially trained emergency life-saving technicians were also given permission to insert tracheal tubes in July 2004 and to administer intravenous epinephrine in April Physicianstaffed ambulances and heliambulances are available in only a few areas. Citizen use of an automated external defibrillator has been legally permitted since July 2004 in Japan. All EMS providers performed CPR according to the Japanese CPR guideline based on the 2000 American Heart Association guideline until September 2006 and the 2005 AHA guideline thereafter. 1,16 Do-not-resuscitate orders or living wills are generally not accepted in Japan, and EMS providers are not permitted to terminate resuscitation in the field. Therefore, most patients with OHCA who were treated by EMS personnel were transported to hospital and were registered in this cohort, excluding cases of decapitation, incineration, decomposition, rigor mortis, or dependent cyanosis. CPR Training for the General Public Systemic CPR training for citizens has been offered mainly by each local fire department. In Japan, 1.4 million citizens per year participated in the systemic CPR training, which consisted of conventional CPR including chest compressions, mouth-to-mouth ventilation, and automated external defibrillator use. 17 Compressiononly CPR was not taught in any resuscitation training program in Japan during the study period. The emergency telephone dispatchers in Japan are basically trained and ordered to give CPR instructions with conventional CPR before EMS arrival. However, it is permitted to encourage bystanders to provide chest compression only CPR if it is difficult for them to administer rescue breathing. Data Collection and Quality Control Data were prospectively collected with a data form based on the Utstein-style reporting guidelines for OHCA such as gender, age, origin (cardiac or noncardiac [external causes, respiratory diseases, cerebrovascular disease, malignant tumors, or other]), type of bystander witness (none, family members, or other), initial cardiac rhythm (ventricular fibrillation [VF], including ventricular tachycardia, pulseless electric activity, or asystole), time course of resuscitation, type of bystanderinitiated CPR (none, chest compression only, or conventional), type of advanced airway management (none, laryngeal mask airway, esophageal obturator airway, or endotracheal intubation), and intravenous fluid and epinephrine (none, administered), as well as return of spontaneous circulation before hospital arrival, 1-month survival, and neurological status 1 month after the event. A series of EMS times of call receipt, vehicle arrival at the scene, contact with patients, initiation of CPR, defibrillation by EMS, and hospital arrival were recorded based on the clock used by each EMS system. The initiation and type of bystander CPR were obtained by EMS interview with the bystanders before leaving the scene. All survivors were followed up for up to 1 month after the event by the EMS personnel in charge. Neurological outcome was determined by follow-up interviews 1 month after successful resuscitation with the cerebral performance category scale: category 1, good cerebral performance; category 2, moderate cerebral disability; category 3, severe cerebral disability; category 4, coma or vegetative state; and category 5, death. 13,14 The data form was filled out by the EMS personnel in cooperation with the physicians in charge of the patient and registered in the computer-based registry system. All data were integrated into the FDMA Web-based database server and then checked by the computer logic and the steering committee. If the data were incomplete, FDMA returned them to the respective fire station, and the data were completed. Statistical Analyses The primary outcome measure was neurologically intact 1-month survival, which was defined as cerebral performance category 1 or 2. 13,14 Secondary outcome measures included return of spontaneous circulation before hospital arrival and 1-month survival. Outcomes of bystander-witnessed OHCAs of noncardiac origin were compared by the type of bystander-initiated CPR. Both bystander-initiated compression-only CPR and conventional CPR with rescue breathing were considered to be bystander CPR, whereas unknown type of bystander-initiated CPR was not. In addition, the effect of each type of bystander-initiated CPR was evaluated after patients were divided into 2 groups, those whose time interval from collapse to the initiation of EMS CPR was 0 to 15 minutes and those whose interval was 15 minutes, because the addition of rescue breathing might have benefit for a long duration of cardiac arrest. 9,10,18,19 Patient characteristics and outcomes by type of bystander-initiated CPR were evaluated with ANOVA for numeric variables and 2 test for categorical variables. The age-adjusted annual incidence of OHCAs was calculated by direct methods using 2005 census data and 1985 Japanese model population. 15,20 Multivariable analysis was used to assess the contribution of bystander-initiated CPR to better neurological outcome; odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated. Potential confounding factors that were biologically essential and considered to be associated with outcomes were included in the multivariable analysis. These variables included gender, age, origin, type of bystander witness, first recorded rhythm, type of advanced airway management, epinephrine, intravenous fluid, time interval from collapse to CPR by EMS, and time interval from collapse to hospital arrival. The number of OHCAs needed to treat to save a life with favorable neurological outcome after OHCA was also calculated. All statistical analyses were performed with the SPSS statistical package version 16.0J (SPSS, Inc, Chicago, Ill). All tests were 2 tailed, and a value of P 0.05 was considered statistically significant. The authors had full access to and take full responsibility for the integrity of the data. All authors have read and agree to the manuscript as written. Results The Figure shows an overview of OHCAs. During these 3 years, adult OHCAs were documented. Of attempted resuscitations, (45.2%) were of noncardiac origin. The age-adjusted annual incidence of OHCAs with noncardiac origin throughout Japan during the study period was 30.6 per person-years, of which 13.6 were external causes, 3.5 were respiratory diseases, 3.2 were cerebrovascular diseases, 2.0 were malignant tumors, and 8.3 were others. Of victims, OHCAs were

3 Kitamura et al Rescue Breathing for Noncardiac OHCA 295 Figure. Overview of EMS-treated cardiac arrests with an abridged Utstein template from January 1, 2005, through December 31, witnessed by bystanders and by EMS, and were not witnessed. After exclusion of the 106 cases without information on bystander-initiated CPR, were eligible for our analyses. Of these, 8878 (20.5%) received chest compression only CPR, 7474 (17.3%) received conventional CPR with rescue breathing, and (62.2%) received no CPR. Among eligible patients, neurological status was not obtained for 196 (0.4%). Demographic characteristics of study patients by type of bystander CPR are given in Table 1. The mean age and male-to-female ratio were higher in the no CPR group than in either the compression-only CPR or the conventional CPR group. External causes accounted for 40% of cases regardless of the type of bystander CPR. Patients in both the compression-only and conventional CPR groups were slightly more likely to have VF as initial rhythm than those in the no CPR group. Both CPR groups were also more likely to receive advanced life support measures such as epinephrine use, tracheal intubation, and intravenous fluid than the no CPR group. The duration from collapse to EMS maneuvers was longer in both the compression-only and conventional CPR groups than in no CPR group. Table 2 shows the outcomes of bystander-witnessed OHCA of noncardiac origin by type of bystander-initiated CPR. The conventional CPR group (1.8%) had a higher rate of neurologically intact 1-month survival than the no CPR group (1.4%; adjusted OR, 1.58; 95% CI, 1.28 to 1.96), but the compression-only CPR group (1.5%) had a survival similar to that of the no CPR group (adjusted OR, 1.19; 95% CI, 0.96 to 1.47). Conventional CPR produced better neurological outcome even referring to chest compression only CPR (adjusted OR, 1.32; 95% CI, 1.03 to 1.69). As for return of spontaneous circulation before hospital arrival (11.2% versus 8.8%; adjusted OR, 1.37; 95% CI, 1.25 to 1.51) and 1-month survival (7.2% versus 5.8%; adjusted OR, 1.41; 95% CI, 1.26 to 1.58), the conventional CPR group also showed significantly better neurological outcome than the no CPR group, whereas the compression-only CPR group did not. The number of OHCAs needed to treat with conventional CPR versus compression-only CPR to save a life with favorable neurological outcome after OHCA was 290. A time-based analysis of the effect of type of bystanderinitiated CPR is shown in Table 3. The conventional CPR group had significantly higher rates of better neurological outcome than the no CPR group both among OHCAs of 0- to 15-minute duration (2.1% versus 1.7%; adjusted OR, 1.39; 95% CI, 1.11 to 1.75) and among 15 minutes (1.1% versus 0.4%; adjusted OR, 3.11; 95% CI, 1.75 to 5.51), although the OR was larger in the long-duration cardiac arrest. Outcome was similar between the compression-only CPR group and the no CPR group regardless of duration of cardiac arrest. Neurologically intact 1-month survival after bystanderwitnessed OHCAs of noncardiac origin according to type of bystander CPR and origin of OHCA is shown in Table 4. Neurologically intact 1-month survival was higher in the conventional CPR group than in the no CPR group for external causes (1.9% versus 1.4%; adjusted OR, 1.69; 95% CI, 1.18 to 2.43), cerebrovascular diseases (2.9% versus

4 296 Circulation July 20, 2010 Table 1. Characteristics of the Study Participants by Type of Bystander CPR No CPR (n ) 2.1%; adjusted OR, 1.58; 95% CI, 0.97 to 2.57), and other causes (1.9% versus 1.5%; adjusted OR, 1.50; 95% CI, 1.00 to 2.25), whereas survival was similar between the compression-only CPR and no CPR groups. For OHCAs with respiratory diseases and malignant tumors, neurological outcome was dismal regardless of the type of bystander CPR. Compression-Only CPR (n 8878) Conventional CPR (n 7474) P* Age, mean (95% CI), y 70.3 ( ) 74.6 ( ) 75.7 ( ) Male, n, % (95% CI) , 62.9 ( ) 5181, 58.4 ( ) 3818, 51.1 ( ) Origin, n, % (95% CI) External causes, n, % (95% CI) , 39.7 ( ) 2968, 33.4 ( ) 2452, 32.8 ( ) Respiratory diseases 3810, 14.2 ( ) 1564, 17.6 ( ) 1371, 18.3 ( ) Cerebrovascular diseases 2953, 11.0 ( ) 1089, 12.3 ( ) 971, 13.0 ( ) Malignant tumors 2524, 9.4 ( ) 803, 9.0 ( ) 471, 6.3 ( ) Other 6940, 25.8 ( ) 2454, 27.6 ( ) 2209, 29.6 ( ) Type of bystander witness, n, % (95% CI) Family members , 67.8 ( ) 5444, 61.3 ( ) 3177, 42.5 ( ) Others 8668, 32.2 ( ) 3434, 38.7 ( ) 4297, 57.5 ( ) Type of first documented rhythm, n, % (95% CI) VF/pulseless VT 982, 3.7 ( ) 418, 4.7 ( ) 386, 5.2 ( ) PEA , 38.3 ( ) 3162, 35.6 ( ) 2945, 39.4 ( ) Asystole , 58.1 ( ) 5298, 59.7 ( ) 4143, 55.4 ( ) Type of advanced airway management, n, % (95% CI) None , 55.5 ( ) 4614, 52.0 ( ) 3819, 51.2 ( ) Laryngeal mask airway 2649, 9.9 ( ) 809, 9.1 ( ) 757, 10.1 ( ) Esophageal obturator airway 7521, 28.0 ( ) 2712, 30.6 ( ) 2280, 30.6 ( ) Endotracheal intubation 1784, 6.6 ( ) 740, 8.3 ( ) 606, 8.1 ( ) Intravenous fluid, n, % (95% CI) 4387, 16.3 ( ) 1583, 17.8 ( ) 1299, 17.4 ( ) Epinephrine, n, % (95% CI) 773, 2.9 ( ) 356, 4.0 ( ) 279, 3.7 ( ) Collapse to call, mean (95% CI), min 3.2 ( ) 3.8 ( ) 4.1 ( ) Collapse to EMS arrival at the scene, mean (95% CI), min 10.1 ( ) 11.4 ( ) 11.8 ( ) Collapse to CPR by EMS, mean (95% CI), min 12.5 ( ) 13.1 ( ) 13.6 ( ) Collapse to shock by EMS, mean (95% CI), min 13.3 ( ) 14.5 ( ) 15.4 ( ) Collapse to hospital arrival, mean (95% CI), min 32.6 ( ) 33.1 ( ) 33.6 ( ) VT indicates ventricular tachycardia; PEA, pulseless electrical activity. *P values are calculated to test the homogeneity among the 3 CPR groups. Calculated for cases with VF as first documented rhythm. Table 2. Discussion From this nationwide registry of OHCA, we have clearly shown that the bystander-initiated conventional CPR with rescue breathing was more effective than either compression-only CPR or no CPR for adult OHCAs of noncardiac origin regardless of the duration of arrest and that the benefit becomes larger in Outcomes of Bystander-Witnessed OHCAs of Noncardiac Origin by Type of Bystander CPR No CPR (n ) Compression-Only CPR (n 8878) Conventional CPR (n 7474) ROSC before hospital arrival, n (%) 2373 (8.8) 815 (9.2) 838 (11.2) Adjusted OR (95% CI) Reference 1.08 ( ) 1.37 ( ) 1-mo survival, n (%) 1557 (5.8) 558 (6.3) 535 (7.2) Adjusted OR (95% CI) Reference 1.17 ( ) 1.41 ( ) Neurologically intact 1-mo survival, n (%) 370 (1.4) 131 (1.5) 136 (1.8) Adjusted OR (95% CI) Reference 1.19 ( ) 1.58 ( ) ROSC indicates return of spontaneous circulation. ORs were adjusted for gender, age, origin, type of bystander witness, first recorded rhythm, type of advanced airway management, epinephrine, intravenous fluid, time interval from collapse to CPR by EMS, and time interval from collapse to hospital arrival.

5 Kitamura et al Rescue Breathing for Noncardiac OHCA 297 Table 3. Neurologically Intact 1-Month Survival After Bystander-Witnessed OHCAs of Noncardiac Origin by Type of Bystander CPR and EMS CPR No CPR Compression-Only CPR Conventional CPR EMS CPR 0 15 min (n ) Neurologically intact 1-mo survival, n (%) 340 (1.7) 118 (1.8) 109 (2.1) Adjusted OR (95% CI) Reference 1.18 ( ) 1.39 ( ) EMS CPR 15 min (n ) Neurologically intact 1-mo survival, n (%) 27 (0.4) 11 (0.5) 24 (1.1) Adjusted OR (95% CI) Reference 1.20 ( ) 3.11 ( ) EMS CPR indicates the time interval from collapse to initiation of CPR by EMS. ORs were adjusted for gender, age, origin, type of bystander witness, first recorded rhythm, type of advanced airway management, epinephrine, intravenous fluid, time interval from collapse to CPR by EMS, and time interval from collapse to hospital arrival. long-duration cardiac arrests. Preceding studies evaluating the effectiveness of type of bystander-initiated CPR for OHCAs of noncardiac origin 8,10,21,22 failed to assess the associations between outcomes and the CPR groups among OHCAs of noncardiac origin because of a lack of statistical power. Unlike these earlier studies, our study was large enough to allow evaluation of the differences in outcomes between the each type of bystanderinitiated CPR among OHCAs of noncardiac origin. Although this study suggests that conventional CPR with rescue breathing is a better approach for OHCAs of noncardiac origin, the absolute survival is very low regardless of type of CPR among this group, and the number of OHCAs needed to treat with conventional CPR versus compressiononly CPR to save a life with favorable neurological outcome after OHCAs of noncardiac origin was large. Even among the witnessed OHCAs of noncardiac origin over 3 years in an entire large country, 10 additional patients survived with better neurological outcome after conventional CPR compared with compression-only CPR. Therefore, the impact of rescue breathing on the overall survival after OHCAs of noncardiac origin was small. Further efforts, including advanced life support techniques and cause-specific treatments, are needed to increase survival after OHCAs of noncardiac origin. Many previous clinical studies have shown the effectiveness of chest compression only CPR for OHCAs of cardiac origin, 7 10 and compression-only CPR is recommended primarily for adult witnessed sudden collapse of cardiac origin. 11 Although 20% to 40% of adult OHCAs are considered to be of noncardiac origin, 1 6 little is known about the difference in the effectiveness of the 2 types of bystander CPR between cardiac and noncardiac OHCAs. 11,12 Our study results could affect the approach used for cardiac arrests of presumed noncardiac causes. Why does rescue breathing have an incremental benefit for OHCAs of noncardiac origin? Most cardiac arrests of noncardiac origin are due to respiratory causes such as drowning and asphyxia. 1 6 Some animal studies showed that conventional CPR was more effective than compression-only CPR for outcomes after cardiac arrests of the asphyxia model. 23,24 In asphyxia, oxygen consumption with carbon dioxide and lactate production continues for several minutes after respiratory arrest before cardiac arrest and depletes the pulmonary oxygen reservoir. Therefore, asphyxia results in hypoxemia and acidemia at the time of cardiac arrest, and rescue breathing would be of considerable help under those conditions. In our study, conventional CPR improved survival after OHCA from external causes, most of which involve respiratory Table 4. Neurologically Intact 1-Month Survival After Bystander-Witnessed OHCAs of Noncardiac Origin by Type of Bystander CPR and Origin of OHCA No CPR Compression-Only CPR Conventional CPR External causes (n ) 10, Neurologically intact 1-mo survival, n (%) 146 (1.4) 45 (1.5) 46 (1.9) Adjusted OR (95% CI) Reference 1.15 ( ) 1.69 ( ) Respiratory diseases (n 6745) Neurologically intact 1-mo survival, n (%) 51 (1.3) 17 (1.1) 19 (1.4) Adjusted OR (95% CI) Reference 0.87 ( ) 1.01 ( ) Cerebrovascular diseases (n 5013) Neurologically intact 1-mo survival, n (%) 61 (2.1) 27 (2.5) 28 (2.9) Adjusted OR (95% CI) Reference 1.26 ( ) 1.58 ( ) Malignant tumors (n 3798) Neurologically intact 1-mo survival, n (%) 9 (0.4) 2 (0.2) 1 (0.2) Adjusted OR (95% CI) Reference 0.63 ( ) 0.51 ( ) Others (n 11,603) Neurologically intact 1-mo survival, n (%) 103 (1.5) 40 (1.6) 42 (1.9) Adjusted OR (95% CI) Reference 1.23 ( ) 1.50 ( ) ORs were adjusted for gender, age, type of bystander witness, first recorded rhythm, type of advanced airway management, epinephrine, intravenous fluid, time interval from collapse to CPR by EMS, and time interval from collapse to hospital arrival.

6 298 Circulation July 20, 2010 compromise. Our findings were also consistent with the inference made from animal models. Cardiac arrest resulting from cerebrovascular diseases might also follow respiratory arrest because of damage to the respiratory center in the brainstem Therefore, rescue breathing would increase survival after cardiac arrests from cerebrovascular diseases in the same way. In this study, the frequency of initial VF among OHCAs of noncardiac origin was very low (4.1%). Preceding studies have also shown lower frequency of VF (range, 5.0% to 11.2%) among OHCA with noncardiac origin 2 4 compared with cardiac origin. 5,8,9,28 The frequency of VF would generally decrease as the rhythm assessment by EMS was delayed. 1 Compared with the preceding studies in Japan, 8,9 the time interval from collapse to EMS maneuvers was slightly longer in this study, and these delays might result in low frequency of initial VF. The racial difference in VF incidence observed in OHCAs of cardiac origin 29,30 might be another possible explanation. Because of this low frequency of VF among OHCAs of noncardiac origin and high survival after OHCA of cardiac origin in Japan, 31,32 the low survival after OHCAs of noncardiac origin shown in this study would not be associated with the EMS system in this area but with the origins of the OHCAs. Our study suggests the need for a systemic approach to CPR training. On the basis of our new data suggesting the incremental benefit of rescue breathing, we recommend that conventional CPR, which includes rescue breathing, should continue to be the standard for OHCAs from presumed noncardiac causes. However, considering that (1) the incremental benefit of rescue breathing for the overall survival is small, (2) the main target patients who can derive benefits from bystander CPR with or without automated external defibrillator shock are those who experience OHCAs of cardiac origin, and (3) bystander CPR is seldom provided, 1,7 9,11 compression-only CPR training should be primarily disseminated as the AHA has recommended. 11 This leads us to support a 2-pronged CPR training strategy: compression-only CPR training for most people 11,33 and conventional CPR (chest compression and rescue breathing) for individuals most likely to witness cardiac arrests with presumed noncardiac causes such as medical professionals and lifeguards. 34 Limitations First, this observational study lacks data on the quality of bystander CPR, and type of bystander CPR administered was not randomized. Laypersons who provide rescue breathing might be better trained and provide more effective chest compressions. Although this study indicates the effectiveness of additional rescue breathing, we cannot explicitly exclude these potential biases. Second, we did not obtain details on OHCA origin. Further detailed information about the quality of bystander CPR and the origin of OHCA would strengthen the evidence for the effectiveness of bystander-initiated CPR. Third, the category of presumed cardiac or noncardiac causes is made clinically, as per the Utstein-style international guidelines for cardiac arrest data reporting. 13,14 Fourth, information on postarrest care is lacking. In-hospital treatment (eg, hypothermia) might affect survival after OHCA. 35 Fifth, information is lacking on laypersons socioeconomic status, including education level or type of employment, which might affect CPR performance. Sixth, as with all epidemiological studies, data integrity, validity, and ascertainment bias are potential limitations. The use of uniform data collection based on the Utsteinstyle guidelines for reporting cardiac arrest, the large sample size, and a population-based design to cover all known adult OHCAs in Japan minimizes these potential sources of biases. Conclusion This nationwide population-based observational study indicates that conventional CPR with chest compressions and rescue breathing had an incremental benefit for improving survival after OHCA of noncardiac origin, but the impact on the overall survival after OHCA was small. Acknowledgments We are greatly indebted to all of the EMS personnel and concerned physicians in Japan and to the Fire and Disaster Management Agency and Institute for Fire Safety and Disaster Preparedness of Japan for their generous cooperation in establishing and maintaining the Utstein database. Sources of Funding This study was supported by a grant for emergency management scientific research from the Fire and Disaster Management Agency (study of a strategy for applying the results of the Utstein report to the improvement of emergency service) and partially by a Grant-in- Aid for Scientific Research ( ) from the Ministry of Education, Culture, Sports, Science, and Technology. None. Disclosures References 1. ECC Committee, Subcommittees, and Task Forces of the American Heart Association AHA guidelines for cardiopulmonary resuscitation and emergency cardiovascular care. Circulation. 2005;112(suppl):IV-1 IV Kuisma M, Alaspää A. Out-of-hospital cardiac arrests of non-cardiac origin: epidemiology and outcome. Eur Heart J. 1997;18: Engdahl J, Bång A, Karlson BW, Lindqvist J, Herlitz J. Characteristics and outcome among patients suffering from out of hospital cardiac arrest of non-cardiac aetiology. Resuscitation. 2003;57: Hess EP, Campbell RL, White RD. Epidemiology, trends, and outcome of out-of-hospital cardiac arrest of non-cardiac origin. Resuscitation. 2007; 72: Iwami T, Hiraide A, Nakanishi N, Hayashi Y, Nishiuchi T, Yukioka H, Yoshiya I, Sugimoto H. Age and sex analyses of out-of-hospital cardiac arrest in Osaka, Japan. Resuscitation. 2003;57: Engdahl J, Holmberg M, Karlson BW, Leupker R, Herlitz J. The epidemiology of out-of-hospital sudden cardiac arrest. Resuscitation. 2002;52: Hallstrom A, Cobb L, Johnson E, Copass M. Cardiopulmonary resuscitation by chest compression alone or with mouth-to-mouth ventilation. N Engl J Med. 2000;342: SOS-KANTO study group. Cardiopulmonary resuscitation by bystanders with chest compression only (SOS-KANTO): an observation study. Lancet. 2007;369: Iwami T, Kawamura T, Hiraide A, Berg RA, Hayashi Y, Nishiuchi T, Kajino K, Yonemoto N, Yukioka H, Sugimoto H, Kakuchi H, Sase K, Yokoyama H, Nonogi H. Effectiveness of bystander-initiated cardiac-only resuscitation for patients with out-of-hospital cardiac arrest. Circulation. 2007;116: Bohm K, Rosenqvist M, Herlitz J, Hollenberg J, Svensson L. Survival is similar after standard treatment and chest compression only in out-ofhospital bystander cardiopulmonary resuscitation. Circulation. 2007;116: Sayre MR, Berg RA, Cave DM, Page RL, Potts J, White RD, for the American Heart Association Emergency Cardiovascular Care Committee. Hands-only (compression-only) cardiopulmonary resuscitation: a call to action for bystander response to adults who experience out-of-hospital

7 Kitamura et al Rescue Breathing for Noncardiac OHCA 299 sudden cardiac arrest: a science advisory for the public from the Am Heart Association Emergency Cardiovascular Care Committee. Circulation. 2008; 117: Koster RW, Bossaert LL, Nolan JP, Zideman D, for the Board of the European Resuscitation Council. Advisory statement of the European Resuscitation Council on Basic Life Support. Available at: index.php/doclibrary/en/viewdoc/775/3/. Accessed July 23, Jacobs I, Nadkarni V, Bahr J, Berg RA, Billi JE, Bossaert L, Cassan P, Coovadia A, D Este K, Finn J, Halperin H, Handley A, Herlitz J, Hickey R, Idris A, Kloeck W, Larkin GL, Mancini ME, Mason P, Mears G, Monsieurs K, Montgomery W, Morley P, Nichol G, Nolan J, Okada K, Perlman J, Shuster M, Steen PA, Sterz F, Tibballs J, Timerman S, Truitt T, Zideman D. Cardiac arrest and cardiopulmonary resuscitation outcome reports: update and simplification of the Utstein templates for resuscitation registries: a statement for healthcare professionals from a task force of the International Liaison Committee on Resuscitation (American Heart Association, European Resuscitation Council, Australian Resuscitation Council, New Zealand Resuscitation Council, Heart and Stroke Foundation of Canada, InterAmerican Heart Foundation, Resuscitation Councils of Southern Africa). Circulation. 2004;110: Cummins RO, Chamberlain DA, Abramson NS, Allen M, Baskett PJ, Becker L, Bossaert L, Delooz HH, Dick WF, Eisenberg MS, Evans TR, Holmberg S, Kerber R, Mullie A, Ornato JP, Sandoe E, Skulberg A, Tunstall-Padoe H, Swanson R, Thies WH. Recommended guideline for uniform reporting of data from out-of-hospital cardiac arrest: the Utstein style. a statement for health professionals from a task force of the American Heart Association, the European Resuscitation Council, the Heart and Stroke Foundation of Canada, and the Australian Resuscitation Council. Circulation. 1991;84: Population Census of Japan. Tokyo, Japan: Japan Statistical Association; Japanese Guidelines for Emergency Care and Cardiopulmonary Resuscitation. 3rd ed. Tokyo, Japan: Health Shuppansha; Ambulance Service Planning Office of Fire and Disaster Management Agency of Japan. Effect of first aid for cardiopulmonary arrest. Available at: Accessed July 23, Valenzuela TD, Roe DJ, Cretin S, Spaite DW, Larsen MP. Estimating effectiveness of cardiac arrest interventions: a logistic regression survival model. Circulation. 1997;96: Ewy GA. Cardiocerebral resuscitation: the new cardiopulmonary resuscitation. Circulation. 2005;111: Vital Statistics of Japan Tokyo, Japan: Health and Welfare Statistics Association; Van Hoeyweghen RJ, Bossaert LL, Mullie A, Calle P, Martens P, Buylaert WA, Delooz H. Quality and efficiency of bystander CPR: Belgian Cerebral Resuscitation Study Group. Resuscitation. 1993;26: Waalewijn RA, Tijssen JG, Koster RW. Bystander initiated actions in outof-hospital cardiopulmonary resuscitation: results from the Amsterdam Resuscitation Study (ARRESUST). Resuscitation. 2001;50: Berg RA, Hilwig RW, Kern KB, Babar I, Ewy GA. Simulated mouthto-mouth ventilation and chest compressions (bystander cardiopulmonary resuscitation) improves outcome in a swine model of prehospital pediatric asphyxial cardiac arrest. Crit Care Med. 1999;27: Berg RA, Hilwig RW, Kern KB, Ewy GA. Bystander chest compressions and assisted ventilation independently improve outcome from piglet asphyxial pulseless cardiac arrest. Circulation. 2000;101: Guyton AC, Hall JE. Textbook of Medical Physiology. 10th ed. Pennsylvania, Pa: WB Saunders Co; 2000: Shapiro S. Management of subarachnoid hemorrhage patients who presented with respiratory arrest resuscitated with bystander CPR. Stroke. 1996;27: Thompson RK, Malina S. Dynamic axial brain-stem distortion as a mechanism explaining the cardiorespiratory changes in increased intracranial pressure. J Neurosurg. 1959;16: Nichol G, Thomas E, Callaway CW, Hedges J, Powell JL, Aufderheide TP, Rea T, Lowe R, Brown T, Dreyer J, Davis D, Idris A, Stiell I, for the Resuscitation Outcomes Consortium Investigators. Regional variation in out-of-hospital cardiac arrest incidence and outcome. JAMA. 2008;300: Nishiuchi T, Hiraide A, Hayashi Y, Uejima T, Morita H, Yukioka H, Shigemoto T, Ikeuchi H, Matsusaka M, Iwami T, Shinya H, Yokota J. Incidence and survival rate of bystander-witnessed out-of-hospital cardiac arrest with cardiac etiology in Osaka, Japan: a population-based study according to the Utstein style. Resuscitation. 2003;59: Becker LB, Han BH, Meyer PM, Wright FA, Rhodes KV, Smith DW, Barrett J. Racial differences in the incidence of cardiac arrest and subsequent survival: the CPR Chicago Project. N Engl J Med. 1993;329: Iwami T, Nichol G, Hiraide A, Hayashi Y, Nishiuchi T, Kajino K, Morita H, Yukioka H, Ikeuchi H, Sugimoto H, Nonogi H, Kawamura T. Continuous improvements of chain of survival increased survival after outof-hospital cardiac arrests: a large-scale population-based study. Circulation. 2009;119: Kitamura T, Iwami T, Kawamura T, Nagao K, Tanaka H, Hiraide A, for the Implementation Working Group for All-Japan Utstein Registry of the Fire and Disaster Management Agency. Nationwide public access defibrillation in Japan. N Engl J Med. 2010;362: Nishiyama C, Iwami T, Kawamura T, Ando M, Yonemoto N, Hiraide A, Nonogi H. Effectiveness of simplified chest compression-only CPR training for the general public: a randomized controlled trial. Resuscitation. 2008;79: Handley AJ. Compression-only CPR: to teach or not to teach? Resuscitation. 2009;80: Neumar RW, Nolan JP, Adrie C, Aibiki M, Berg RA, Böttiger BW, Callaway C, Clark RS, Geocadin RG, Jauch EC, Kern KB, Laurent I, Longstreth WT Jr, Merchant RM, Morley P, Morrison LJ, Nadkarni V, Peberdy MA, Rivers EP, Rodriguez-Nunez A, Sellke FW, Spaulding C, Sunde K, Vanden Hoek T. Post-cardiac arrest syndrome: epidemiology, pathophysiology, treatment, and prognostication: a scientific statement from the International Liaison Committee on Resuscitation; the American Heart Association Emergency Cardiovascular Care Committee; the Council on Cardiovascular Surgery and Anesthesia; the Council on Cardiopulmonary, Perioperative, and Critical Care; the Council on Clinical Cardiology; the Council on Stroke. Circulation. 2008;118: CLINICAL PERSPECTIVE Little is known about the difference in the effectiveness of bystander-initiated conventional cardiopulmonary resuscitation (CPR) with rescue breathing and chest compression only CPR for adult out-of-hospital cardiac arrests (OHCAs) of noncardiac origin, which account for 20% to 40% of adult OHCAs. The large, prospective, population-based registry covering all of Japan enabled us to evaluate the effectiveness of each type of bystander CPR for OHCAs of noncardiac origin. Although this study demonstrated the actual benefits of the addition of rescue breathing for OHCAs of noncardiac origin, the absolute survival was very low regardless of type of CPR, and the number of OHCAs needed to treat with conventional CPR versus compression-only CPR to save a life with favorable neurological outcome was 290. Even among the OHCAs of noncardiac origin over 3 years in an entire large country, 10 additional patients survived with better neurological outcome after conventional CPR compared with compression-only CPR. On the basis of the findings of this investigation and other studies supporting the effectiveness of compression-only CPR for OHCAs of cardiac origin, we suggest a 2-pronged CPR training strategy: chest compression only CPR training for most people and conventional CPR with rescue breathing for individuals who are likely to witness cardiac arrests such as medical professionals and lifeguards. Efforts to teach and encourage laypersons to perform any bystander-initiated CPR (especially compression-only CPR) would improve survival after OHCAs.