Impact of Automated External Defibrillator as a Recent Innovation for the Resuscitation of Cardiac Arrest Patients in an Urban City of Japan.

CONTEXT/AIMS: We retrospectively analyzed the characteristics of prehospital care for cardiopulmonary arrest (CPA) to identify the predictors of a good recovery (GR) among the recent changes in the management of Japanese prehospital care. SETTINGS AND
DESIGN: This study was a retrospective medical chart review. SUBJECTS AND METHODS: We reviewed the transportation records written by emergency medical technicians and the characteristics of prehospital management of out-of-hospital (oh) CPA described by the Sunto-Izu Fire Department from April 2016 to March 2017. The cases were divided into two groups: a GR group (cerebral performance category of 1-3 at 1 month after CPA) and a poor recovery (PR) group.
RESULTS: During the analysis period, there were 545 cases of CPA. The average age in the GR group (n = 19) was significantly younger than that in the PR group. The proportions of patients with witnessed collapse, automated external defibrillator (AED) executed by a bystander, ventricular fibrillation during prehospital cardiopulmonary resuscitation (CPR), defibrillation-induced cardioversion, cardiogenic arrest, and oh-return of spontaneous circulation (ROSC) were significantly greater in the GR group than in the PR group. The proportions of telephone CPR conducted by operator, instrumentally secured airways, and administration of epinephrine were significantly smaller in the GR group than in the PR group. A multivariate analysis showed that the significant predictors of GR were bystander AED, ROSC, not instrumentally secured airway, and younger age.
CONCLUSIONS: This study showed that patients with CPA who were younger, underwent AED executed by a bystander, and obtained oh-ROSC had a higher chance of a favorable outcome.

INTRODUCTION

In Japan, the rate of a favorable outcome after cardiopulmonary arrest (CPA) is still low at 1.9%–3.1%.[1] Efforts have been made to improve the chance of obtaining a favorable outcome after cardiac arrest, including the provision of advanced cardiac life support by emergency medical technicians (EMTs), the dispatch of physician-staffed helicopters, the application of hands-only cardiopulmonary resuscitation (CPR), the conduct of telephone CPR by an operator of the fire department, and the placement of automated external defibrillators (AEDs) in public spaces, such as hotels, corner stores, and police boxes in Japan.[23456]

In Japan, the guidelines for prehospital care for CPA are changing. Local governments have established the emergency medical system (EMS) as a public service, and anyone can call an ambulance free of charge by dialing 119. Most local governments use a one-tier emergency system, with the fire department usually dispatching an EMS team of three EMTs in an ambulance after receiving a 119 call. However, in some areas, another ambulance carrying a team including a medical doctor from a local hospital may arrive at the scene at the same time. In 1991, EMTs who had undergone the necessary training were allowed to use semiautomatic defibrillators, secure peripheral venous access, and establish a supraglottic airway with an esophageal tracheal combitube, laryngeal mask, or tube. Since 2004, some EMTs have been allowed to perform tracheal intubation after receiving special training. In addition, all EMTs can now use a semiautomatic defibrillator, while members of the public are able to use AEDs. Since 2006, some EMTs have been approved to administer 1 mg of epinephrine intravenously every 5 min until obtaining the return of spontaneous circulation (ROSC) after successfully securing venous access and obtaining permission from a medical doctor by telephone.[23456]

The Sunto-Izu Fire Department is located approximately 130 km from Tokyo and covers Numazu, Ito, Izu, Izunokuni, Higashi Izu, Kannami, and Shimizu City of Shizuoka Prefecture, which has a population of approximately 460,000. The Red Cross of Shizuoka Prefecture has published the location of AEDs in these areas. The Sunto-Izu Fire Department also provides basic life support (BLS) training for citizens, including instructions on how to use AEDs and how to perform hands-only CPR. In 2016, this fire department provided BLS 417 times and trained 11,109 citizens in BLS.

Given the above-mentioned recent changes in the management of Japanese prehospital care, we retrospectively analyzed the characteristics of prehospital care for CPA to identify predictors of a good recovery (GR) in the area under the jurisdiction of the Sunto-Izu Fire Department.

SUBJECTS AND METHODS

The protocol of this retrospective study was approved by the institutional review board, and the examinations were conducted in accordance with the standards of good clinical practice and the Declaration of Helsinki.

We retrospectively reviewed the transportation records written by EMTs and the characteristics of prehospital management of out-of-hospital (oh) CPA described by the Sunto-Izu Fire Department using the modified Utstein-style template from April 2016 to March 2017. All oh-CPA patients transported by the EMS were eligible for the study. We excluded patients who were neither treated nor transported by the EMS because of signs of death, such as rigor mortis or postmortem lividity, or unsurvivable injury (scoring 6 on the abbreviated injury scale). The EMS of the Sunto-Izu Fire Department of Shizuoka has five central stations (Numazu, Shimizu, Tagata, Ito, and Higashi-Izu), 597 staff members, and 139 vehicles. Each central station has 0–4 substations in 921 Km.[2] In this area, there were two acute critical care centers that mainly received patients with CPA. When the central station receives a 119 call, the nearest substation dispatches an EMS team in an ambulance. Each EMS team consists of three members.

The cases were divided into two groups: a GR group (cerebral performance category [CPC] of 1–3 at 1 month after CPA) and a poor recovery (PR) group (CPC of 4–5). CPC was defined as follows: (1) normal or mild cerebral disability; (2) moderate cerebral disability; (3) severe cerebral disability; (4) coma/vegetative state; and (5) dead.

The following variables were, respectively, analyzed between the two groups: sex, age, duration from first call to hospital arrival, witnessed collapse, telephone CPR conducted by operator, bystander CPR, bystander AED use, cause of arrest (presumed cardiogenic or noncardiogenic), rhythm strip electrocardiogram at scene, ventricular fibrillation during prehospital resuscitation, defibrillation, type of airway (tracheal intubation, supraglottic airway, or mask ventilation only), intravenous cannulation, administration of epinephrine, and ROSC.

Both the Chi-squared test and the nonpaired Student's t-test were used for statistical analyses. A P value of <0.05 was considered statistically significant. A multivariate analysis using a partition analysis was used to evaluate the independent factors associated with GR separately using the JMP 12.0 statistical software program (SAS Japan Incorporation, Tokyo, Japan). The variables included in the multivariate analysis were those with significance levels of P < 0.05 based on a univariate analysis. Data are represented as the mean ± standard deviation.

RESULTS

During the analysis period, there were 928 cases of CPA in the Sunto-Izu Fire Department of Shizuoka prefecture. Among them, 383 untransported cases were excluded due to the signs of death. The overall oh-ROSC rate was 3.8% (n = 21), and 3.4% of patients (n = 19) made a GR. Table 1 shows a comparison between the GR and PR groups. The average age in the GR group was significantly younger than that in the PR group. The proportions of patients with witnessed collapse, AED executed by a bystander, ventricular fibrillation during prehospital CPR, defibrillation-induced cardioversion, cardiogenic arrest, and oh-ROSC were significantly greater in the GR group than in the PR group. The proportions of telephone CPR conducted by an operator, instrumentally secured airways, and administration of epinephrine were significantly smaller in the GR group than in the PR group. The proportion of tracheal intubations did not differ significantly between the two groups. No patients obtained a GR after the prehospital administration of epinephrine.

Table 1

Results of analysis between two groups

A multivariate analysis revealed the following significant predictors of GR: bystander AED (LogWorth 5.4, P < 0.0001), ROSC (LogWorth 2.8, P = 0.001), not instrumentally secured airway (LogWorth 1.8, P = 0.01), and age (LogWorth 1.6, P < 0.05).

DISCUSSION

This study showed that patients with CPA who were younger, underwent AED executed by a bystander, and obtained oh-ROSC had a higher chance of obtaining a favorable outcome. In contrast, a supraglottic airway was a negative predictor for a favorable outcome among the recent changes in the management of Japanese prehospital care.

This study demonstrated the importance of AED executed by a bystander among recent endeavors for improving the prognosis of CPA. In Japan, it takes approximate 8.5 min from the first call for EMTs to contact patients.[6] Eight minutes is too long to prevent whole cerebral ischemia due to cardiac arrest. Since July 2004, it has been legal for any citizen in Japan to use an AED, and public-access AEDs have become increasingly available.[678] The AED has greatly improved the rate of resuscitation of patients with CPA.[91011] Kitamura et al. reported the results of a total of 312,319 adults who had experienced oh-cardiac arrest; 12,631 of these patients had ventricular fibrillation and had an arrest that was of cardiac origin and witnessed by bystanders.[8] In 462 of those patients (3.7%), shocks were administered by laypersons using public-access AEDs, and the proportion increased (from 1.2% to 6.2%) as the number of public-access AEDs increased. Among patients who received shocks from public-access AEDs, 31.6% were alive at 1 month with minimal neurologic impairment. Early defibrillation was associated with a good neurologic outcome after a cardiac arrest with ventricular fibrillation. Accordingly, the increase in the numbers of AEDs in a given area and early access was key to improve the outcomes of patients with cardiac arrest. To establish this purpose, dispatching BLS-trained and AED-equipped police, a mobile phone positioning system to dispatch lay volunteers trained in CPR, and AED-equipped radio-controlled aircraft have been tested in the field.[121314]

To ensure full recovery from CPA in the field, it is important to achieve oh-ROSC, because the shorter the duration of compromised cerebral perfusion, the less ischemic cerebral injury observed.[15] In addition, not obtaining ROSC makes survival impossible. For these reasons, oh-ROSC was a positive predictor for a favorable outcome in the present study. However, obtaining oh-ROSC through advanced cardiac life support is itself not associated with an improvement in the survival to hospital discharge in patients with CPA, so achieving a balance between obtaining oh-ROSC over time and early transportation to perform aggressive medical treatment in hospital may be important for treating patients with CPA in the prehospital setting.[16]

In the present study, the use of a supraglottic airway was associated with a poor outcome. The laryngeal mask, tube, and esophageal tracheal combitube are alternatives to tracheal intubation for securing an airway. The International Liaison Committee on Resuscitation previously recommended the classic laryngeal mask and combitube as a substitute for tracheal intubation.[17] However, a meta-analysis for endotracheal intubation versus supraglottic airway placement in oh-CPA revealed that patients with oh-CPA who receive endotracheal intubation by EMS were more likely to obtain ROSC, survive to hospital admission, and survive neurologically intact than those treated with a supraglottic airway device.[18] To resolve this issue, a multicenter cluster randomized controlled trial of the clinical and cost effectiveness of the supraglottic airway device versus tracheal intubation in the initial airway management of oh-CPA is now underway.[19]

The associations of a younger age, witnessed collapse, and ventricular fibrillation during prehospital CPR with a favorable outcome observed here have been reported in several previous studies[1920212223242526] One reason for the inclusion of age as a factor is the decrease in the cerebral reserve function with age.[272829] However, some reports on the neurologic outcome in successfully resuscitated elderly patients found that the outcome depended more on the cardiac arrest characteristics than the age. This discrepancy might be due to the background of the participants.[3031] As Japan is one of the world's most rapidly aging societies, this may affect the extrapolation of our results.[32]

CONCLUSIONS

This study showed that patients with CPA who were younger, underwent AED executed by a bystander, and obtained oh-ROSC had a higher chance of obtaining a favorable outcome among the recent changes in the management of Japanese prehospital care. Future studies should explore how patients with CPA receive AED. Based on the present findings, we do not recommend that EMTs try to establish a supraglottic airway.

Financial support and sponsorship

This work received funds from the Ministry of Education, Culture, Sports, Science and Technology (MEXT)-Supported Program for the Strategic Research Foundation at Private Universities, 2015-2019. The title is the constitution of total researching system for comprehensive disaster, medical management, corresponding to wide-scale disaster.

Conflicts of interest

There are no conflicts of interest.