American Journal of Emergency Medicine 33 (2015) 677–681
Contents lists available at ScienceDirect
American Journal of Emergency Medicine journal homepage: www.elsevier.com/locate/ajem
Original Contribution
Relationship between duration of prehospital resuscitation and favorable prognosis in ventricular fibrillation Takahiro Arima, MD a,⁎, Osamu Nagata, MD b,1, Koji Sakaida, MD a, Takeshi Miura, MD a, Hiroyuki Kakuchi, MD a, Katsuki Ikeda, MD a, Tomoya Mizushima, MD a, Azusa Takahashi, MD a a b
Emergency Department, Funabashi Municipal Medical Center, Funabashi City, Chiba, Japan Department of Anesthesiology, The Cancer Institute Hospital of JFCR, Koto Ward, Tokyo, Japan
a r t i c l e
i n f o
Article history: Received 4 September 2014 Received in revised form 26 January 2015 Accepted 17 February 2015
a b s t r a c t Objective: There appears to be an optimal point in balancing the relative benefits of extending the resuscitation time to obtain return of spontaneous circulation in the prehospital setting and the initiation of therapies such as extracorporeal cardiopulmonary resuscitation (CPR). This study investigated how prehospital CPR duration is related to survival and neurologic outcome in ventricular fibrillation (VF) and tried to find the tolerable time for prehospital resuscitation. Materials and methods: Out-of-hospital cardiac arrest patients with VF in Funabashi City, Japan, from January 2009 to December 2013 were reviewed. Resuscitation teams that included physicians were dispatched to incident sites. Survival rate at 24 hours and neurologic outcome at 30 days were analyzed with respect to prehospital CPR duration. Results: A total of 172 patients were evaluated. Seventy-three patients were alive at 24 hours. Thirty-four patients had favorable neurologic outcomes after 30 days. Of the 69 patients who required prolonged prehospital CPR (N30 minutes), 6 were alive at 24 hours, and only 1 had a favorable neurologic outcome at 30 days. Logistic regression model showed that both survival rate at 24 hours and neurologic outcome at 30 days deteriorated with the increase in prehospital CPR duration (both P b .001). Conclusion: The prognosis of out-of-hospital cardiac arrest patients with VF deteriorated with the increase in prehospital CPR duration. Favorable results are less likely especially in cases of prolonged prehospital CPR (N30 minutes). Therefore, it may be necessary to consider transportation to a more definitive treatment facility rather than extending conventional CPR in the prehospital setting. © 2015 Elsevier Inc. All rights reserved.
1. Introduction Early return of spontaneous circulation (ROSC) brings a favorable prognosis if achieved [1-4]. In Funabashi City, Japan, this has led to the prioritization of cardiopulmonary resuscitation (CPR) to promote early ROSC in the prehospital setting over transportation to a hospital, occasionally leading to prolonged resuscitation times. However, this change in prioritization could be an obstacle to performing immediate extracorporeal CPR (E-CPR). Extracorporeal CPR is reported to be effective for patients in whom ROSC cannot be achieved by conventional CPR [5-11] and especially when ventricular fibrillation (VF) persists [12-18]. As a consequence, E-CPR has recently become the standard technique for patients with refractory VF in Japan.
⁎ Corresponding author at: Emergency Department, Funabashi Municipal Medical Center, 1-21-1 Kanasugi, Funabashi City, Chiba 260 8677, Japan. Tel.: +81 47 438 3321; fax: +81 47 438 7323. E-mail address: [email protected] (A. Takahiro). 1 Tel.: +81 3 3520 0111; fax: +81 3 3520 0141. http://dx.doi.org/10.1016/j.ajem.2015.02.031 0735-6757/© 2015 Elsevier Inc. All rights reserved.
There seems to be an optimal point in balancing the relative benefits of extending the resuscitation time to achieve ROSC in the prehospital setting and of initiating E-CPR at treatment facilities. However, it is unknown exactly how long conventional CPR should be administered before transportation. This study investigated how duration of prehospital resuscitation is related to survival and neurologic outcome in VF and attempted to establish the maximum tolerable time for prehospital CPR. 2. Material and methods 2.1. Setting and patients The data of consecutive out-of-hospital cardiac arrest patients with initial VF from January 2009 to December 2013 in Funabashi City were reviewed. Patients were excluded if they were younger than age 18 years, pregnant, or posttrauma. This study was approved by the Ethics Committee of Funabashi Municipal Medical Center. Funabashi City has a population of approximately 609 000, and the residential area is 86 km 2. Funabashi City has a 24-hour physician car system that transports physicians to incident sites and operates all
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year round. This 2-tiered response system is activated when a cardiac arrest is anticipated. In some cases, the physician team arrives at the incident site earlier than first response teams. The arrival time depends on the location of the incident site. All physicians had more than 3 years of experience and had received certification from the American Heart Association's Advanced Cardiovascular Life Support (ACLS) course. In attempts to achieve early ROSC in the prehospital setting, resuscitation teams of 1 or 2 physicians and 6 paramedics provided ACLS in accordance with the American Heart Association guidelines (as revised in 2010). Resuscitation effort was continued at incident sites, until 1 of 2 outcomes occurred: (1) the patient had return of circulation or (2) the rhythm degenerated into asystole. If ROSC could not be achieved and the rhythm converted to persistent asystole regardless of the resuscitation effort, the physician terminated resuscitation with the family's consent at the incident site based on their judgment; otherwise, the patient was transported to hospital, especially when it is not possible to terminate CPR due to the family's request and surrounding conditions. 2.2. Outcome measures The outcomes measured were cerebral performance based on cerebral performance category (CPC) [19] at 30 days and survival rate at 24 hours after admission, in relation to CPR duration in the prehospital setting. Cerebral performance category according to the GlasgowPittsburgh Outcome Categorization of Brain Injury was graded on a 5-point scale (1, normal; 5, brain death). Here, favorable outcomes were defined as CPC scores of 1 and 2 and unfavorable outcomes as CPC scores of 3 to 5. Prehospital CPR duration, defined as the time from the initiation of CPR by paramedics until either ROSC or termination of CPR, was measured by paramedics. Return of spontaneous circulation was defined as spontaneous circulation maintained for greater than 5 minutes. 2.3. Data collection and analysis Data were recorded by paramedics of the Funabashi Fire Department using the Utstein style; these data are managed nationwide by the Japanese national government through the Fire and Disaster Management Agency. Cerebral performance category at 30 days was collected from medical records, with no patients lost to follow-up. Values are presented as mean ± SD and median (interquartile range). Logistic regression was used to reveal the correlation between the outcome and prehospital CPR duration. To determine the cutoff value for prehospital CPR duration, receiver operating characteristic curve analysis with area under curve calculations was performed. All statistical analysis was performed using JMP 10 (SAS Institute Inc, Cary, NC). 3. Results 3.1. Patient and events characteristics A total of 172 cardiac arrest patients with initial VF were included and reviewed as shown in Fig. 1. All cases were followed up after 30 days. The study population consisted of 131 men (76.2%) and 41 women (23.8%), with a mean age of 64.7 ± 15.1 years. Of the total cases, 134 (78.0%) were witnessed, and 92 (53.5%) involved bystander CPR. Cardiac causes accounted for 76.7% of total cardiac arrests (132 cases). Patient characteristics and CPR data are given in the Table. Advanced tracheal devices, including tracheal tubes and supraglottic devices, were used in 136 patients (79%). Adrenaline was administered in 141 patients (82.0%). The antiarrhythmic drugs amiodarone and lidocaine were administered in 15 (8.7%) and 67 patients (39.0%), respectively. The median number of shocks applied was 3 (interquartile range, 1-7), and shock-resistant VF, where greater than or equal to 2 shocks were required to resolve VF at least transiently, was encountered
Fig. 1. Patient flowchart.
in 106 (47.1%) patients. Return of spontaneous circulation was observed in 100 (58.1%) patients. Median time from crew notification to CPR was 11 (interquartile range, 9-13) minutes. Median time to first defibrillation, intravenous catheterization, and insertion of tracheal devices were 13 (10-15) minutes, 20 (16-24) minutes, and 25 (19-30) minutes, respectively. Median time for CPR duration was 26 (13-38) minutes in the prehospital setting. 3.2. Outcome Of the total cases, 73 patients (42.4%) were alive at 24 hours, and 34 patients (19.8%) had favorable neurologic outcomes at 30 days. All these patients were resuscitated before transportation to hospitals. On the other hand, 69 patients required prolonged CPR for greater than 30 minutes in the prehospital setting; of them, 6 patients (8.7%) survived at 24 hours, and only 1 patient (1.4%) had a favorable neurologic outcome. The correlation between the outcome and prehospital CPR duration is shown in Fig. 2, with resuscitation duration divided into the following ranges: 1 to 5 minutes, 6 to 10 minutes, 11 to 20 minutes, 21 to 30 minutes,
Table Patient, event, and CPR characteristics Variables
Total (n = 172)
Age (y) Male sex, n (%) Witnessed arrest, n (%) Bystander CPR, n (%) Cardiac cause, n (%) Advanced tracheal devices used, n (%) Adrenaline, n (%) Antiarrhythmic drugs administered, n (%) Lidocaine/amiodarone Median no. of shocks (interquartile range) Shock-resistant VF, n (%) Conversion of rhythm to asystole, n (%) ROSC, n (%) CPR terminated at the incident site, n (%) Median interval (min) from crew notification To CPR (interquartile range) To first defibrillation To intravenous catheterization To insertion of tracheal devices Median interval (min) from CPR to ROSC (interquartile range) Median duration (min) of prehospital CPR (interquartile range)
64.7 ± 15.1 131 (76.2) 134 (78.0) 92 (53.5) 132 (76.7) 136 (79.0) 141 (82.0) 82 (47.7) 67/15 3 (1-7) 106 (61.6) 56 (33.0) 100 (58.1) 24 (14.0) 11 (9-13) 13 (10-15) 20 (16-24) 25 (19-30) 14 (8-21) 26 (13-38)
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Fig. 2. Survival rate at 24 hours and favorable neurologic outcome rate at 30 days in relation to CPR duration.
and greater than 30 minutes. In terms of the 24 hours survival rate, it remained at more than 80% when CPR duration was less than 10 minutes. When the CPR duration was greater than 20 minutes, the survival rate decreased to less than 50%; it declined to 8.7% in cases of prolonged CPR for greater than 30 minutes. Likewise, the proportion of favorable neurologic outcome at 30 days was 81% when the CPR duration was 1 to 5 minutes. However, it decreased to less than 10% when the duration was greater than 20 minutes and to 1.4% in cases of prolonged CPR for greater than 30 minutes. Furthermore, a mean number of 7 (interquartile range, 310) shocks were required for defibrillation when extended CPR greater than 30 minutes was performed. This suggests that persistent VF contributed to the administration of prolonged CPR. Logistic regression model showed that the rate of both 24 hours survival and favorable neurologic outcome at 30 days significantly decreased with increased CPR duration (P b .001 and P b .001, respectively) (Fig. 3). In addition, the receiver operating characteristic curve indicated that the cutoff values for survival rate at 24 hours and for favorable neurologic outcome at 30 days were 27 minutes (sensitivity, 84.9% and specificity, 72.7 %) and 17 minutes (sensitivity, 80.4% and specificity, 77.3%), respectively, when the area under curve was a maximum (0.86 and 0.88, respectively) (Fig. 4). At these points, good outcomes were maximized. 4. Discussion Early ROSC is one of the most important factors that predicts a good prognosis, and the outcome deteriorates with the increase in CPR duration [2-4]. However, previous studies focused on the data of in-hospital patients. Our study was designed to establish a protocol for E-CPR for out-of-hospital cardiac patients with VF and to find a tolerable time for prehospital CPR. A recent study [20] reported a correlation between
Fig. 4. The receiver operating characteristic curve for CPR duration.
the duration of resuscitation efforts and functional outcome after outof-hospital cardiac arrests, and its conclusion was similar to our study. There seems to be a balance between extending the resuscitation time to assure ROSC in the prehospital setting and the initiation of therapies such as E-CPR. Extended CPR before the initiation of E-CPR decreases the possibility of a good outcome. Recent studies suggest that a good outcome can be obtained if the time from arrest to E-CPR is shorter than 60 minutes [5,11,20-23]. Therefore, it may be argued that it is better to transport the patient to a more definitive facility while using a mechanical device for chest compression rather than administering CPR in the prehospital setting. However, mechanical devices are not always usable during loading, for instance, because patients' bodies should be bent while passing through narrow stairs or space. Therefore, it might be unacceptably risky to end qualified CPR at sites in some cases. Here, physicians were dispatched to incident sites to provide ACLS in attempts to achieve early ROSC. Rather than performing early interruption of CPR to initiate earlier E-CPR, resuscitation efforts continued at the scene in an attempt to attain ROSC. Survival at 24 hours was achieved in 73 patients (42.4%), and favorable neurologic outcomes at 30 days were seen in 34 patients (19.8%). However, 69 patients required prolonged CPR for greater than 30 minutes in the prehospital setting; of them, 6 patients (8.7%) survived at 24 hours, and only 1 patient (1.4%) had a favorable neurologic outcome. This suggests that prolonged CPR greater than 30 minutes in the prehospital setting does not lead to a good outcome, and the duration should not exceed 30 minutes. The cutoff value indicated by the receiver operating characteristic curve for survival rate at 24 hours was 28 minutes and that for favorable
Fig. 3. Logistics regression model for correlation between the outcome and CPR duration.
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neurologic outcomes at 30 days was 18 minutes. These values can represent reasonable goals for the duration of CPR in the prehospital setting. This study examined only VF. First, in general, out-of-hospital cardiac arrest patients with VF have more favorable outcomes than those who present with asystole and pulseless electrical activity [24-26]. Notably, only 1 patient, a 28-year-old man, survived with a favorable outcome at 30 days after 43 minutes of CPR. In this case, VF persisted throughout the resuscitation. This indicates that the possibility of full recovery remains as long as VF continues [27,28]. On the other hand, it is widely known that conversion of arrhythmia into asystole predicts an unfavorable outcome [29]. Second, although E-CPR is still a controversial treatment for cardiac arrest and further studies evaluating the role of E-CPR are warranted [30], many studies have shown that E-CPR improved patient outcome after refractory VF [12-18]. This is likely attributable to the increase in coronary perfusion pressure and contribution to ROSC, which are thought to occur in E-CPR [31]. In addition, immediate percutaneous coronary intervention (PCI) improves coronary perfusion and helps alleviate VF [13-16]. It appears that the combination of E-CPR and immediate PCI might contribute to favorable outcomes in refractory VF [13,14,32]. The rate of VF was just 7.9% during the observation over the 5 years. This figure was much smaller than the rate of 30% reported in another study [33]. The delay in defibrillation might have contributed to this low incidence of VF in a local city in Japan; in fact, the median interval from crew notification to first defibrillation was 13 minutes in our system, which was longer than around 8 minutes in other systems [34,35]. Other possible reasons for this difference could be due to differences in race/ethnicity or in prevalence of ischemic heart disease. Our study had the following limitations. First, the effects of in-hospital care such as therapeutic mild hypothermia, immediate PCI, and other treatments were not investigated in the present study. Furthermore, data on E-CPR were not available because this study was a preliminary report related to the introduction of E-CPR. Second, conventional teaching is/was that providers should continue resuscitation for 30 minutes before resuscitation is considered futile [36]. It could be that this implicit policy in practice led to the observed difference in outcomes after 30 minutes. However, resuscitation was continued with a strong belief that a favorable outcome can be achievable as long as VF persists. When considering the termination of CPR, permanent asystole was the more determining factor rather than the duration of CPR. Third, the effectiveness of amiodarone in refractory VF seems to be superior to that of lidocaine in terms of ROSC [34,35]. Nevertheless, there were only 15 cases in which amiodarone was administered, due to the fact that we have only recently begun to use amiodarone in the prehospital setting (from September 2012). However, amiodarone did not improve the ultimate outcome of alive discharge; therefore, the impact of the small number of cases that were given amiodarone might not be considerable. Fourth, although the criterion standard of resuscitation outcome is generally discharge from hospital, we used survival rate at 24 hours and CPC at 30 days, as these are the parameters recorded in the domestic database kept by the Fire and Disaster Management Agency. Finally, the cause of cardiac arrest was not confirmed by autopsy but was based on clinical data and diagnosis. This may have led to a lack of accuracy in diagnosis.
5. Conclusion The prognosis of out-of-hospital cardiac arrest patients deteriorated with increased CPR duration in cases of VF. Favorable results are less likely especially in cases of prolonged prehospital CPR (N 30 minutes). Therefore, it may be necessary to consider transportation to a more definitive treatment facility rather than extend conventional CPR in the prehospital setting.
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Contents lists available at ScienceDirect
American Journal of Emergency Medicine journal homepage: www.elsevier.com/locate/ajem
Original Contribution
Relationship between duration of prehospital resuscitation and favorable prognosis in ventricular fibrillation Takahiro Arima, MD a,⁎, Osamu Nagata, MD b,1, Koji Sakaida, MD a, Takeshi Miura, MD a, Hiroyuki Kakuchi, MD a, Katsuki Ikeda, MD a, Tomoya Mizushima, MD a, Azusa Takahashi, MD a a b
Emergency Department, Funabashi Municipal Medical Center, Funabashi City, Chiba, Japan Department of Anesthesiology, The Cancer Institute Hospital of JFCR, Koto Ward, Tokyo, Japan
a r t i c l e
i n f o
Article history: Received 4 September 2014 Received in revised form 26 January 2015 Accepted 17 February 2015
a b s t r a c t Objective: There appears to be an optimal point in balancing the relative benefits of extending the resuscitation time to obtain return of spontaneous circulation in the prehospital setting and the initiation of therapies such as extracorporeal cardiopulmonary resuscitation (CPR). This study investigated how prehospital CPR duration is related to survival and neurologic outcome in ventricular fibrillation (VF) and tried to find the tolerable time for prehospital resuscitation. Materials and methods: Out-of-hospital cardiac arrest patients with VF in Funabashi City, Japan, from January 2009 to December 2013 were reviewed. Resuscitation teams that included physicians were dispatched to incident sites. Survival rate at 24 hours and neurologic outcome at 30 days were analyzed with respect to prehospital CPR duration. Results: A total of 172 patients were evaluated. Seventy-three patients were alive at 24 hours. Thirty-four patients had favorable neurologic outcomes after 30 days. Of the 69 patients who required prolonged prehospital CPR (N30 minutes), 6 were alive at 24 hours, and only 1 had a favorable neurologic outcome at 30 days. Logistic regression model showed that both survival rate at 24 hours and neurologic outcome at 30 days deteriorated with the increase in prehospital CPR duration (both P b .001). Conclusion: The prognosis of out-of-hospital cardiac arrest patients with VF deteriorated with the increase in prehospital CPR duration. Favorable results are less likely especially in cases of prolonged prehospital CPR (N30 minutes). Therefore, it may be necessary to consider transportation to a more definitive treatment facility rather than extending conventional CPR in the prehospital setting. © 2015 Elsevier Inc. All rights reserved.
1. Introduction Early return of spontaneous circulation (ROSC) brings a favorable prognosis if achieved [1-4]. In Funabashi City, Japan, this has led to the prioritization of cardiopulmonary resuscitation (CPR) to promote early ROSC in the prehospital setting over transportation to a hospital, occasionally leading to prolonged resuscitation times. However, this change in prioritization could be an obstacle to performing immediate extracorporeal CPR (E-CPR). Extracorporeal CPR is reported to be effective for patients in whom ROSC cannot be achieved by conventional CPR [5-11] and especially when ventricular fibrillation (VF) persists [12-18]. As a consequence, E-CPR has recently become the standard technique for patients with refractory VF in Japan.
⁎ Corresponding author at: Emergency Department, Funabashi Municipal Medical Center, 1-21-1 Kanasugi, Funabashi City, Chiba 260 8677, Japan. Tel.: +81 47 438 3321; fax: +81 47 438 7323. E-mail address: [email protected] (A. Takahiro). 1 Tel.: +81 3 3520 0111; fax: +81 3 3520 0141. http://dx.doi.org/10.1016/j.ajem.2015.02.031 0735-6757/© 2015 Elsevier Inc. All rights reserved.
There seems to be an optimal point in balancing the relative benefits of extending the resuscitation time to achieve ROSC in the prehospital setting and of initiating E-CPR at treatment facilities. However, it is unknown exactly how long conventional CPR should be administered before transportation. This study investigated how duration of prehospital resuscitation is related to survival and neurologic outcome in VF and attempted to establish the maximum tolerable time for prehospital CPR. 2. Material and methods 2.1. Setting and patients The data of consecutive out-of-hospital cardiac arrest patients with initial VF from January 2009 to December 2013 in Funabashi City were reviewed. Patients were excluded if they were younger than age 18 years, pregnant, or posttrauma. This study was approved by the Ethics Committee of Funabashi Municipal Medical Center. Funabashi City has a population of approximately 609 000, and the residential area is 86 km 2. Funabashi City has a 24-hour physician car system that transports physicians to incident sites and operates all
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year round. This 2-tiered response system is activated when a cardiac arrest is anticipated. In some cases, the physician team arrives at the incident site earlier than first response teams. The arrival time depends on the location of the incident site. All physicians had more than 3 years of experience and had received certification from the American Heart Association's Advanced Cardiovascular Life Support (ACLS) course. In attempts to achieve early ROSC in the prehospital setting, resuscitation teams of 1 or 2 physicians and 6 paramedics provided ACLS in accordance with the American Heart Association guidelines (as revised in 2010). Resuscitation effort was continued at incident sites, until 1 of 2 outcomes occurred: (1) the patient had return of circulation or (2) the rhythm degenerated into asystole. If ROSC could not be achieved and the rhythm converted to persistent asystole regardless of the resuscitation effort, the physician terminated resuscitation with the family's consent at the incident site based on their judgment; otherwise, the patient was transported to hospital, especially when it is not possible to terminate CPR due to the family's request and surrounding conditions. 2.2. Outcome measures The outcomes measured were cerebral performance based on cerebral performance category (CPC) [19] at 30 days and survival rate at 24 hours after admission, in relation to CPR duration in the prehospital setting. Cerebral performance category according to the GlasgowPittsburgh Outcome Categorization of Brain Injury was graded on a 5-point scale (1, normal; 5, brain death). Here, favorable outcomes were defined as CPC scores of 1 and 2 and unfavorable outcomes as CPC scores of 3 to 5. Prehospital CPR duration, defined as the time from the initiation of CPR by paramedics until either ROSC or termination of CPR, was measured by paramedics. Return of spontaneous circulation was defined as spontaneous circulation maintained for greater than 5 minutes. 2.3. Data collection and analysis Data were recorded by paramedics of the Funabashi Fire Department using the Utstein style; these data are managed nationwide by the Japanese national government through the Fire and Disaster Management Agency. Cerebral performance category at 30 days was collected from medical records, with no patients lost to follow-up. Values are presented as mean ± SD and median (interquartile range). Logistic regression was used to reveal the correlation between the outcome and prehospital CPR duration. To determine the cutoff value for prehospital CPR duration, receiver operating characteristic curve analysis with area under curve calculations was performed. All statistical analysis was performed using JMP 10 (SAS Institute Inc, Cary, NC). 3. Results 3.1. Patient and events characteristics A total of 172 cardiac arrest patients with initial VF were included and reviewed as shown in Fig. 1. All cases were followed up after 30 days. The study population consisted of 131 men (76.2%) and 41 women (23.8%), with a mean age of 64.7 ± 15.1 years. Of the total cases, 134 (78.0%) were witnessed, and 92 (53.5%) involved bystander CPR. Cardiac causes accounted for 76.7% of total cardiac arrests (132 cases). Patient characteristics and CPR data are given in the Table. Advanced tracheal devices, including tracheal tubes and supraglottic devices, were used in 136 patients (79%). Adrenaline was administered in 141 patients (82.0%). The antiarrhythmic drugs amiodarone and lidocaine were administered in 15 (8.7%) and 67 patients (39.0%), respectively. The median number of shocks applied was 3 (interquartile range, 1-7), and shock-resistant VF, where greater than or equal to 2 shocks were required to resolve VF at least transiently, was encountered
Fig. 1. Patient flowchart.
in 106 (47.1%) patients. Return of spontaneous circulation was observed in 100 (58.1%) patients. Median time from crew notification to CPR was 11 (interquartile range, 9-13) minutes. Median time to first defibrillation, intravenous catheterization, and insertion of tracheal devices were 13 (10-15) minutes, 20 (16-24) minutes, and 25 (19-30) minutes, respectively. Median time for CPR duration was 26 (13-38) minutes in the prehospital setting. 3.2. Outcome Of the total cases, 73 patients (42.4%) were alive at 24 hours, and 34 patients (19.8%) had favorable neurologic outcomes at 30 days. All these patients were resuscitated before transportation to hospitals. On the other hand, 69 patients required prolonged CPR for greater than 30 minutes in the prehospital setting; of them, 6 patients (8.7%) survived at 24 hours, and only 1 patient (1.4%) had a favorable neurologic outcome. The correlation between the outcome and prehospital CPR duration is shown in Fig. 2, with resuscitation duration divided into the following ranges: 1 to 5 minutes, 6 to 10 minutes, 11 to 20 minutes, 21 to 30 minutes,
Table Patient, event, and CPR characteristics Variables
Total (n = 172)
Age (y) Male sex, n (%) Witnessed arrest, n (%) Bystander CPR, n (%) Cardiac cause, n (%) Advanced tracheal devices used, n (%) Adrenaline, n (%) Antiarrhythmic drugs administered, n (%) Lidocaine/amiodarone Median no. of shocks (interquartile range) Shock-resistant VF, n (%) Conversion of rhythm to asystole, n (%) ROSC, n (%) CPR terminated at the incident site, n (%) Median interval (min) from crew notification To CPR (interquartile range) To first defibrillation To intravenous catheterization To insertion of tracheal devices Median interval (min) from CPR to ROSC (interquartile range) Median duration (min) of prehospital CPR (interquartile range)
64.7 ± 15.1 131 (76.2) 134 (78.0) 92 (53.5) 132 (76.7) 136 (79.0) 141 (82.0) 82 (47.7) 67/15 3 (1-7) 106 (61.6) 56 (33.0) 100 (58.1) 24 (14.0) 11 (9-13) 13 (10-15) 20 (16-24) 25 (19-30) 14 (8-21) 26 (13-38)
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Fig. 2. Survival rate at 24 hours and favorable neurologic outcome rate at 30 days in relation to CPR duration.
and greater than 30 minutes. In terms of the 24 hours survival rate, it remained at more than 80% when CPR duration was less than 10 minutes. When the CPR duration was greater than 20 minutes, the survival rate decreased to less than 50%; it declined to 8.7% in cases of prolonged CPR for greater than 30 minutes. Likewise, the proportion of favorable neurologic outcome at 30 days was 81% when the CPR duration was 1 to 5 minutes. However, it decreased to less than 10% when the duration was greater than 20 minutes and to 1.4% in cases of prolonged CPR for greater than 30 minutes. Furthermore, a mean number of 7 (interquartile range, 310) shocks were required for defibrillation when extended CPR greater than 30 minutes was performed. This suggests that persistent VF contributed to the administration of prolonged CPR. Logistic regression model showed that the rate of both 24 hours survival and favorable neurologic outcome at 30 days significantly decreased with increased CPR duration (P b .001 and P b .001, respectively) (Fig. 3). In addition, the receiver operating characteristic curve indicated that the cutoff values for survival rate at 24 hours and for favorable neurologic outcome at 30 days were 27 minutes (sensitivity, 84.9% and specificity, 72.7 %) and 17 minutes (sensitivity, 80.4% and specificity, 77.3%), respectively, when the area under curve was a maximum (0.86 and 0.88, respectively) (Fig. 4). At these points, good outcomes were maximized. 4. Discussion Early ROSC is one of the most important factors that predicts a good prognosis, and the outcome deteriorates with the increase in CPR duration [2-4]. However, previous studies focused on the data of in-hospital patients. Our study was designed to establish a protocol for E-CPR for out-of-hospital cardiac patients with VF and to find a tolerable time for prehospital CPR. A recent study [20] reported a correlation between
Fig. 4. The receiver operating characteristic curve for CPR duration.
the duration of resuscitation efforts and functional outcome after outof-hospital cardiac arrests, and its conclusion was similar to our study. There seems to be a balance between extending the resuscitation time to assure ROSC in the prehospital setting and the initiation of therapies such as E-CPR. Extended CPR before the initiation of E-CPR decreases the possibility of a good outcome. Recent studies suggest that a good outcome can be obtained if the time from arrest to E-CPR is shorter than 60 minutes [5,11,20-23]. Therefore, it may be argued that it is better to transport the patient to a more definitive facility while using a mechanical device for chest compression rather than administering CPR in the prehospital setting. However, mechanical devices are not always usable during loading, for instance, because patients' bodies should be bent while passing through narrow stairs or space. Therefore, it might be unacceptably risky to end qualified CPR at sites in some cases. Here, physicians were dispatched to incident sites to provide ACLS in attempts to achieve early ROSC. Rather than performing early interruption of CPR to initiate earlier E-CPR, resuscitation efforts continued at the scene in an attempt to attain ROSC. Survival at 24 hours was achieved in 73 patients (42.4%), and favorable neurologic outcomes at 30 days were seen in 34 patients (19.8%). However, 69 patients required prolonged CPR for greater than 30 minutes in the prehospital setting; of them, 6 patients (8.7%) survived at 24 hours, and only 1 patient (1.4%) had a favorable neurologic outcome. This suggests that prolonged CPR greater than 30 minutes in the prehospital setting does not lead to a good outcome, and the duration should not exceed 30 minutes. The cutoff value indicated by the receiver operating characteristic curve for survival rate at 24 hours was 28 minutes and that for favorable
Fig. 3. Logistics regression model for correlation between the outcome and CPR duration.
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neurologic outcomes at 30 days was 18 minutes. These values can represent reasonable goals for the duration of CPR in the prehospital setting. This study examined only VF. First, in general, out-of-hospital cardiac arrest patients with VF have more favorable outcomes than those who present with asystole and pulseless electrical activity [24-26]. Notably, only 1 patient, a 28-year-old man, survived with a favorable outcome at 30 days after 43 minutes of CPR. In this case, VF persisted throughout the resuscitation. This indicates that the possibility of full recovery remains as long as VF continues [27,28]. On the other hand, it is widely known that conversion of arrhythmia into asystole predicts an unfavorable outcome [29]. Second, although E-CPR is still a controversial treatment for cardiac arrest and further studies evaluating the role of E-CPR are warranted [30], many studies have shown that E-CPR improved patient outcome after refractory VF [12-18]. This is likely attributable to the increase in coronary perfusion pressure and contribution to ROSC, which are thought to occur in E-CPR [31]. In addition, immediate percutaneous coronary intervention (PCI) improves coronary perfusion and helps alleviate VF [13-16]. It appears that the combination of E-CPR and immediate PCI might contribute to favorable outcomes in refractory VF [13,14,32]. The rate of VF was just 7.9% during the observation over the 5 years. This figure was much smaller than the rate of 30% reported in another study [33]. The delay in defibrillation might have contributed to this low incidence of VF in a local city in Japan; in fact, the median interval from crew notification to first defibrillation was 13 minutes in our system, which was longer than around 8 minutes in other systems [34,35]. Other possible reasons for this difference could be due to differences in race/ethnicity or in prevalence of ischemic heart disease. Our study had the following limitations. First, the effects of in-hospital care such as therapeutic mild hypothermia, immediate PCI, and other treatments were not investigated in the present study. Furthermore, data on E-CPR were not available because this study was a preliminary report related to the introduction of E-CPR. Second, conventional teaching is/was that providers should continue resuscitation for 30 minutes before resuscitation is considered futile [36]. It could be that this implicit policy in practice led to the observed difference in outcomes after 30 minutes. However, resuscitation was continued with a strong belief that a favorable outcome can be achievable as long as VF persists. When considering the termination of CPR, permanent asystole was the more determining factor rather than the duration of CPR. Third, the effectiveness of amiodarone in refractory VF seems to be superior to that of lidocaine in terms of ROSC [34,35]. Nevertheless, there were only 15 cases in which amiodarone was administered, due to the fact that we have only recently begun to use amiodarone in the prehospital setting (from September 2012). However, amiodarone did not improve the ultimate outcome of alive discharge; therefore, the impact of the small number of cases that were given amiodarone might not be considerable. Fourth, although the criterion standard of resuscitation outcome is generally discharge from hospital, we used survival rate at 24 hours and CPC at 30 days, as these are the parameters recorded in the domestic database kept by the Fire and Disaster Management Agency. Finally, the cause of cardiac arrest was not confirmed by autopsy but was based on clinical data and diagnosis. This may have led to a lack of accuracy in diagnosis.
5. Conclusion The prognosis of out-of-hospital cardiac arrest patients deteriorated with increased CPR duration in cases of VF. Favorable results are less likely especially in cases of prolonged prehospital CPR (N 30 minutes). Therefore, it may be necessary to consider transportation to a more definitive treatment facility rather than extend conventional CPR in the prehospital setting.
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