1. Background

Out-of-Hospital Cardiac Arrest (OHCA) is a leading cause of mortality worldwide, although the incidence and mortality of OHCA treated by Emergency Medical Services (EMS) is uncertain, with variations influencing the exact nature of the global burden [1]. Every year more than 350,000 people fall victim to sudden, unexplained OHCA in the United States, and reports from 35 communities suggested an incidence of 55 per 100,000 person-years. Unfortunately, only about 10% of victims survived this dramatic event [2]. In Europe, it is estimated that 275,000 people have all-rhythm OHCA, with incidence of about 37.2/100,000 and only 10.55% surviving to hospital discharge [3]. OHCA affects 110,000 individuals in Japan annually [4] with a survival rate of 7.6%. In China, the incidence is 48.1/100,000, [5] i.e. 583,000 victims in a total population of 1.4 billion, while the survival rate in Beijing is a dismal 1.3% [6].

OHCA is a time-critical disease, and early Cardiopulmonary Resuscitation (CPR) is associated with a favourable prognosis. The emergency medical dispatcher is an essential link in the chain of survival [7], and many countries have implemented telephone-assisted CPR (T-CPR) and related training programmes. T-CPR is an effective means for the first witness to perform CPR in timely fashion, which not only improves the CPR ratio of the first witnesses

[8] but can also improve the effectiveness of CPR and improve the prognosis [9,10]. The European Resuscitation Council Guidelines for Resuscitation 2010 first indicated that a protocol for suspected CA should be devised for dispatchers [11]. In 2015, the International Guide issued by the American Heart Association emphasised the importance of T-CPR

[12] under the moniker “dispatch-assisted CPR”, which involves dispatchers providing CPR instruction to callers or bystanders by telephone [13]. Because little is known about T-CPR in China, we investigated the cognition of T-CPR among EMS staff by means of an online questionnaire survey [14] conducted among the different levels of emergency centres in China from December 2018 to June 2019.

2. Methods

China has an area of ≈9,600,000 km2 and its population in 2019 was ≈1,395 million, covering 34 provincial administrative units. The free emergency number 120 is used to call for an ambulance in most areas of China. Emergency services are provided 24 hours every day. An ambulance is dispatched from the nearest emergency station when called. EMS systems are single-tiered and government-funded- some are independent emergency stations, some are hospital-based stations, and others are mixed. At least one emergency driver and one emergency doctor are deployed in an ambulance, with an accompanying nurse and/or first-aid assistant in some areas.

2.1. Study Design and Population

The survey respondents were EMS staff including emergency doctors, emergency nurses, emergency dispatchers and first-aid assistants from 15 provinces, representative across China. To be eligible for inclusion in the study, each EMS system had to be an independently operated EMS unit, meaning the unit must have its own dispatch system.

After three rounds of expert consultation of the questionnaire, we presented it from site registration forms and an electronic Internet-based survey of all participating EMS systems in the study. A standardised survey form was constructed online (wjx.cn), delivered by the WeChat App and filled out via android/iOS smartphone or the website. Respondents to the survey were eligible if specified as EMS providers in the 15 provinces. The questionnaire mainly consists of two parts: the recognition and implementation of T-CPR among respondents.

2.2. Survey Content and Administration

A cross-sectional descriptive study was conducted from December 2018 to January 2019 using a Web- based system. A survey of perception of T-CPR among EMS providers in China was filled out by personnel from emergency centres. Each EMS involved had a designated local principal investigator who was responsible for verifying data. In addition, the completed questionnaires were re-verified by statisticians, and uncompleted or logistically wrong questionnaires were excluded.

3. Data Analysis

Data collation, statistical description, and statistical analysis were performed using IBM SPSS Statistics 22 software (IBM, Armonk, NY, USA). Continuous variables were summarised by mean ± standard deviation; the composition distribution and rate were used to describe the basic distribution characteristics of the research objects. We assessed the differences in the perception of T-CPR among responding EMS providers in China by either chi-square test or Fisher exact test. Multivariable analysis was used to assess factors associated with the cognition of T-CPR among EMS respondents by using logistic regression models; odds ratios (OR) and their 95% confidence intervals (CI) were calculated. All tests were two- tailed, and P values of <.05 were considered statistically significant.

The authors had full access to, and take responsibility for, the integrity of the data.

4. Results

4.1. Characteristics of survey respondents

A total of 1,191 questionnaires were collected. Four invalid questionnaires were eliminated, leaving 1,187 valid completed questionnaires. The survey covered

15 provincial administrative units from Beijing, Qinghai, Jiangxi, Ningxia, Xinjiang, Chongqing, Guangdong, Zhejiang, Guizhou, Shanghai, Hainan, Jiangsu, Shanxi, Inner Mongolia, and Hebei. The distribution of questionnaires in each province is shown in Figure 1 Distribution of questionnaires in provinces that participated in the survey (The map in Figure1 is made from the website, http://c.dituhui.com/apps.).

The number of respondents at provincial capital level, city level, and county level was 266 (22.4%), 714 (60.2%), and 207 (17.4%), respectively. Among

the respondents, 436 were male (36.7%) and 751 were female (63.3%). Age distribution ranged between 20 and 60 years old (Table 1). The average age was 32.1±7.2 years, with 85.2% in the 20- to 39- year-old age group. A total of 256 dispatchers (21.6%), 494 emergency doctors (41.6%), 400 emergency nurses (33.7%), and 37 medical emergency assistants (3.1%) was involved in the survey. Most of the respondents (503 [42.4%]) had professional work experience of less than 5 years, followed by 356 (30.0%) with 5–10 years’

experience. There were 713 (60.1%) respondents with junior professional titles, 309 (26%) at intermediate level, 66 (5.6%) at senior level, and 99

(8.3%) at other levels (Table 1).

Figure 1: Distribution of questionnaires in provinces that participated in the survey.

The map in Fig.1 is made from the website, http://c.dituhui.com/apps.

Table 1: Characteristics of survey respondents. Workload of emergency personnel and recognised OHCA via telephone in 12 hours

4.2. Number of cardiac arrests recognised in 12 hours by dispatchers receiving emergency calls

The distribution of the number of emergency telephone calls accepted by 256 dispatchers within 12 hours is presented in Table 2. The largest proportion was within 50 (80/256, 31.3%), followed by 50–100 (43/256, 16.8%) and 101–150 (39/256, 15.2%). Among the 256 dispatchers, the number of sudden CAs that could be recognised by telephone among the emergency calls received within 24 hours was the highest in 1–3 cases (95 respondents, 37.1%), followed by 0 cases (79, 30.9%), 4–10 cases (60, 23.4%), and more than 10 cases (16, 6.3%). The other six dispatchers were unsure in determining the number of cases recognised to be CA in a 12-hour period.

Table 2: Workload of emergency personnel and recognised OHCA via telephone in 12 hours.

4.3. Number of cardiac arrests recognised in 12 hours by other staff receiving emergency calls

The distribution of the number of ambulance runs in 24 hours among 931 other emergency personnel is also shown in Table 2. Respondents most frequently did 5–9 runs, i.e., 352 (37.8%); followed by 387

(30.8%) with 0–4 runs, 180 (19.3%) with 10–14 runs,

59 (6.3%) with 15–19 runs, and 46 (4.9%) with ≥20 runs. In addition, 7 respondents (0.8%) were uncertain about the number of runs. Before arriving at the scene, 512 (55.0%) of the 931 emergency personnel never recognised whether the patient had a CA by phone; 261 (28.0%) could recognise 1–3 CA

patients, 90 (9.7%) were able to recognise 4–10

cases, and 24 (2.6%) recognised more than 10 people with CA. In addition, 44 (4.7%) rescuers were unsure of the number of CA patients.

4.4. Monitoring the quality of T-CPR

Among the 352 respondents who believed that the implementation of T-CPR should include the quality of CPR by bystanders, the top three operations to detect the quality of CPR conducted by bystanders were the frequency of chest compression (337, 95.7%), position of hands when compressing (324, 92.0%), and compression duration and number of compression interruptions (298, 84.7%), followed by depth of chest compression (290, 82.4%), frequency of ventilation (if any) (278, 79.0%), whether the chest rebounded during compression (266, 75.6%), and ventilation time (if any) (253, 71.9%).

4.5. Differences among respondents’ characteristics concerning knowledge about T- CPR

Baseline characteristics of respondents showed differences among various aspects of knowledge about T-CPR (Table 3), for which chi-square test values were calculated. Among the 960 (80.9%) respondents who know about T-CPR, the knowledge rate varies among EMS providers from 54.1% to 91.0% (chi-square=38.1, P<.001). Level of EMS (chi-square=27.4, P<.001), education background of EMS providers (Fisher exact test=22.0, P<.001), vocation (chi-square=47.9, P<.001), and professional title (chi-square=13.7, P=0.032) differed in respect of the use of medical priority dispatch system [15] (MPDS). Gender (chi-square=9.6, P<.001) and vocation (chi-square test=82.6, P<.001) varied with regard to monitoring the quality of bystander CPR among 428 out of 1,187 (59.9%) respondents.

Table 3: Differences among respondents’ characteristics regarding knowledge about T-CPR.

4.6. EMS provider factors associated with knowledge of T-CPR in China

In the multivariate analysis (Table 4), a higher workload among dispatchers (P<.001; OR=1.002; 95% CI, 1.001– 1.003) was significantly associated with better knowledge of T-CPR. Emergency doctor (P<.001; OR=0.051; 95% CI, 0.019–0.138), emergency nurse (P=.011; OR=0.347; 95% CI, 0.154–0.786), medical emergency assistant(P=.012; OR=0.337; 95% CI, 0.145–0.784) were associated with worse knowledge of T-CPR.

Table 4: EMS providers’ factors associated with knowledge of T-CPR in China.

4.7. Implementation of T-CPR

As shown in Table 5, of the 960 participants who knew T-CPR, 213 (22.2%) occasionally recognised CA by phone for patients with unconsciousness, 205 (21.4%) sometimes recognised CA, 190 (19.8%) often recognised CA, 188 (19.6%) always recognised CA, and 164 (17.1%) never recognised CA. Of the 796 respondents who recognised CA events, 714 (89.7%) will further implement T-CPR, of whom 236 (29.6%) always, 167 (21.0%) sometimes, 162 often (20.4%), and 149 (18.7%) occasionally would implement T-CPR, while another 82 (10.3%) said they would not implement T-CPR. In the implementation of T-CPR, the most commonly recommended treatment method for bystanders is chest compression + artificial breathing (310 respondents, 43.4%), followed by simple chest compression (216, 30.3%) and chest compression + artificial respiration + AED (140, 19.6%). In the implementation of T-CPR, the percentage of bystanders who could start CPR according to telephone instructions was 5% (202 respondents, 28.3%), followed by 50% and above (153, 21.4%) and 10% (124, 17.4%). The proportion of onlookers who continued to implement CPR until arrival of first responders was 5% (222 respondents, 31.1%), followed by 50% and above (131, 18.3%) and 10% (92, 12.9%).

Table 5: Implementation of T-CPR

5. Discussion

Globally it is estimated that, on average, less than 10% of all patients with OHCA will survive [16]. T- CPR can effectively improve bystander CPR, pre- hospital return of spontaneous circulation (ROSC), and even the prognosis of OHCA patients. A before- and-after interventional trial of dispatcher-assisted CPR for out-of-hospital CA in Singapore showed a significant increase in bystander CPR and ROSC after the intervention [17]. Implementation of a regional T-CPR programme and outcomes after out- of-hospital CA indicated that implementation of a guideline-based T-CPR bundle of care was independently associated with significant improvements in the provision and timeliness of T- CPR, survival to hospital discharge, and survival with favourable functional outcome [18]. In a study of the effect of a dispatcher-assisted CPR programme and location of out-of-hospital CA on survival and neurological outcomes for out-of-hospital CA cases in private settings, bystander CPR was associated with improved neurological recovery only when dispatcher assistance was provided [10].

The results of our questionnaire survey showed that there are some regional differences among the 15 provinces surveyed. Knowledge of T-CPR varied among vocation of EMS providers (dispatcher, doctor, nurse, and others). Whether use MPDS was significantly differed in terms of the level of EMS unit, background of education, vocation, and professional title. According to the survey, the increased workload of dispatchers may improve their knowledge of T-CPR. More dispatchers appear to know about T-CPR, which suggested dispatches may have more chances to guide CPR by telephone because they work via phone. Some additional aspects should be acknowledged as part of these considerations. There is a lack of systematic research on CPR in China, and clinical research on T-CPR is also inadequate. It is necessary to study current guidelines and formulate new ones suitable for China's national circumstances.

6. Limitation

First, this questionnaire was distributed online and was not distributed widely to EMS personnel across every city in China, so the sample cohort was lacking in size. Although there is a risk of selection bias, it is assumed that the EMS population in general has similar difficulties when facing T-CPR. Second, this survey may not have fully captured the complexity of different responses to OHCA across China. Therefore, there may be other questions to be asked that have not been considered in this survey.

7. Conclusion

Throughout China, there are substantial and important differences in the understanding and implementation of T-CPR among EMS personnel. Further professional training in T-CPR is urgently required to improve outcomes of OHCA in China.

Declarations

Ethics approval and consent to participate: see supplemental material: Ethics approval.pdf

Consent for publication

All authors agreed to publish the paper

Availability of data and materials

Data are available upon reasonable request

Competing interests

No

Acknowledgements

We wish to thank all dedicated survey respondents for their participation, and Beijing Municipal Science & Technology Commission for funding. We thank Hugh McGonigle, from Liwen Bianji, Edanz Group China (www.liwenbianji.cn/ac), for editing the English text of a draft of the manuscript.

Conflicts of Interest and Source of Funding

There are no financial and personal relationships with other people or organisations that could influence this paper. COI statements are available for all authors.

The study was funded by Ministry of Science and Technology of the People’s Republic of China, the National Science and Technology Fundamental Resources Investigation Project (Item number 2018FY100600) and Beijing Municipal Science and Technology Commission (Item number Z191100004419003). The funding organisations had no influence on the data analysis or preparation of the manuscript.

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