Elsevier

Resuscitation

Volume 150, May 2020, Pages 50-59
Resuscitation

Clinical paper
Epidemiology and outcome of emergency medical service witnessed out-of-hospital-cardiac arrest by prodromal symptom: Nationwide observational study

https://doi.org/10.1016/j.resuscitation.2020.02.042Get rights and content

Abstract

Background

Although emergency medical service– (EMS-) witnessed out-of-hospital-cardiac arrest (OHCA) has a high survival rate and potential for prevention of progression to cardiac arrest, its characteristics and prodromal symptoms are not well known. The purpose of this study was to investigate the epidemiologic characteristics and outcome of EMS-witnessed OHCA by focusing on its prodromal symptoms.

Methods

Population-based observational study was conducted for resuscitation-attempted EMS-witnessed adult OHCAs between 2012 and 2017. The prodromal symptoms were categorized according to the patients’ chief complaints, which were checked in the EMS run sheets: no prodromal, respiratory, cardiac, neurologic, gastrointestinal (GI), or other symptom. If multiple complaints were checked, the patient was assigned to multiple groups. The OHCA characteristics and time from EMS scene arrival to cardiac arrest were investigated by symptom groups and presumed etiology of OHCA. The age- and sex-standardized survival rate and good neurological outcome rate were calculated for each symptom group.

Results

Of 12,969 eligible OHCAs, 5246 (40.5%) had prodromal symptoms, 1410 (10.9%) had respiratory symptoms, 505 (3.9%) had cardiac symptoms, 1987 (15.3%) had neurologic symptoms, and 541 (4.2%) had GI symptoms. Of 9361 patients with cardiac etiology, 3522 (37.6%) had prodromal symptoms, and patients with cardiac symptoms had the best rate of survival to discharge and good neurological outcome (42.7% and 38.2%, respectively). Of 3424 patients with non-cardiac etiology, 1651 (48.2%) had prodromal symptoms, and patients with respiratory symptoms had the best survival outcomes (19.0%). The age- and sex-standardized rates of good neurological outcome were better in patients with prodromal symptoms than in patients with cardiac etiology and no prodromal symptoms (cardiac, 30.4%; neurologic, 9.8%; respiratory, 8.9%; GI 7.3%; and no prodromal symptoms, 6.8%). EMS-witnessed OHCA occurred earlier in patients with no prodromal symptoms (5–9 min from EMS arrival) than in those with prodromal symptoms (10–14 min).

Conclusion

About 40% of EMS-witnessed OHCA patients had prodromal symptom before cardiac arrest. In cardiac etiology, patients with cardiac symptoms had the best rate of survival to discharge and good neurological outcome. Promoting public awareness of prodromal symptoms is needed to earn time for preparedness and prevention of progression to cardiac arrest.

Introduction

Out-of-hospital cardiac arrest (OHCA) is a major public health burden around the world.1 Although the concept of chain of survival was introduced to improve the outcome of OHCA, the survival rate still remains low.2 One of the reasons for low survival is that cardiac arrest occurs suddenly and little is known about an individual’s specific condition before it occurs; thus, it cannot be prepared for.3

A victim of emergency medical service– (EMS-) witnessed OHCA is not in cardiac arrest when an emergency medical technician (EMT) arrives, but progresses to cardiac arrest during transportation to the hospital.4, 5 EMS-witnessed OHCA makes up about 7–14% of total OHCA, and it has a higher survival rate than other OHCA5, 6, 7, 8 because EMT can immediately treat the patient and the time interval from collapse to the start of cardiopulmonary resuscitation (CPR) and defibrillation is short.6, 9 This characteristic makes EMS-witnessed OHCA a valuable opportunity to gain information about the pre-arrest situation of OHCA.3, 10 Therefore, studies on EMS-witnessed OHCA were conducted to learn of its characteristics and the prodromal symptoms of cardiac arrest.10, 11

The prevalence of prodromal symptoms in cardiac arrest has been reported differently in studies.5, 10, 11 Although about 50% of OHCA with cardiac etiology had symptoms of acute myocardial infarction (AMI), EMS-witnessed OHCA had 80–90% of prodromal symptoms.5, 11, 12 There are also variations of prognosis according to the prodromal symptom of OHCA. A Japanese study reported that patients with prodromal symptoms had better outcomes than those without prodromal symptoms.10 In a North American study, patients with chest pain had a higher survival rate, but patients with dyspnea or unconsciousness had a poorer prognosis.5 The typical symptoms of AMI, such as chest pain, are relatively well known to the public; however, unusual symptoms such as dyspnea and vomiting are less familiar and it can be reasons to delay activating EMS.12 Despite the importance of early EMS activation, there are still few studies on prodromal symptoms of OHCA, especially for non-cardiac etiology.13 It is still unclear what prodromal symptoms appear before cardiac arrest and whether these warning symptoms have prognostic value according to the etiology of OHCA. Cardiac arrest worsen rapidly once it occurs.14, 15 If a patient or bystander knows of the prodromal symptoms and activates EMS earlier, EMT might be able to avoid OHCA or EMT earns time for treatment and the proportion of EMS-witnessed OHCA, which has a higher survival rate, can be increased.9, 10 EMT also can prepare for high-risk patients based on knowledge of prodromal symptoms.

The aim of this study was to investigate the epidemiologic characteristics and outcomes of EMS-witnessed OHCA, focusing on its prodromal symptoms. We also examined the time from EMS scene arrival to occurrence of cardiac arrest according to the symptoms to investigate the time window of EMT to avoid OHCA or to prepare for OHCA.

Section snippets

Study setting

In Korea, the National Fire Agency (NFA) operates EMS exclusively. There are four level of EMS personnel in Korean NFA: level 1 EMT, level 2 EMT, basic level EMT, and nurse. The level 1 EMT are graduates of emergency rescue department in the university and functioned as US EMT-intermediate level (EMT-I). They can provide IV fluid administration and apply advance airway (supraglottic airway and endotracheal intubation) to the OHCA patients, following the EMS CPR protocol.2 However, drug

Study population

Of the 171,534 EMS-assessed OHCAs during the study period (The incidence of OHCA per 100,000 population per year was 56.2), a total of 12,969 patients were included in the study population: 9361 cases of cardiac etiology and 3424 cases of non-cardiac etiology (Fig. 1).

Demographic findings

Among 12,969 EMS-witnessed OHCAs, 7723 cases (59.5%) had no prodromal symptoms, 1987 cases (15.3%) had neurologic symptoms, 1410 cases (10.9%) had respiratory symptoms, 505 cases (3.9%) had cardiac symptoms, and 541 cases (4.2%)

Discussion

This study investigated the characteristics of EMS-witnessed OHCA according to its prodromal symptoms using the national OHCA database. The numbers showed that 37.6% of OHCA with cardiac etiology had prodromal symptoms and 48.2% of non-cardiac etiology had prodromal symptoms. In cardiac etiology, patients with cardiac symptoms had the best survival outcome, while in non-cardiac etiology, patients with respiratory symptoms had the best survival outcome. In EMS-witnessed OHCA, most cardiac

Conclusion

Forty percent of the EMS-witnessed OHCA patients had prodromal symptoms before cardiac arrest. Of the cardiac etiology patients, the patients with cardiac symptoms had the best rate of survival to discharge and good neurological outcome compared with other symptom groups. Of the non-cardiac etiology patients, those with respiratory symptoms had the best survival outcome. Since most EMS-witnessed OHCA occurred in 5–9 min from EMS arrival, promoting awareness of prodromal symptoms is needed to

Funding acknowledgement

This study was supported by the National Fire Agency of Korea and the Korea Centers for Disease Control and Prevention (KCDC).

Conflict of interest

All authors have no other relationships/conditions/circumstances that present potential conflict of interest.

CRediT authorship contribution statement

Sun Young Lee: Data curation, Formal analysis, Writing - original draft. Kyoung Jun Song: Conceptualization, Investigation, Writing - review & editing, Supervision. Sang Do Shin: Project administration, Conceptualization, Supervision. Ki Jeong Hong: Data curation, Writing - review & editing.

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