a b s t r a c t

Background: video call based Dispatcher-assisted cardiopulmonary resuscitation (V-DACPR) has been suggested to improve the quality of bystander cardiopulmonary resuscitation. In the current system, dispatchers must con- vert the audio calls to video calls to provide V-DACPR. We aimed to develop new audio call-to-video call transi- tion protocols and test its efficacy and safety compared to conventional DACPR(C-DACPR).

Methods: This was a randomized controlled simulation trial that compared the quality of bystander chest com-

pression that was performed under three different DACPR protocols: C-DACPR, V-DACPR with rapid transition, and V-DACPR with delayed transition. adult volunteers excluding healthcare providers were recruited for the trial. The primary outcome of the study was the mean proportion of adequate hand positioning during chest com- pression.

Results: Simulation results of 131 volunteers were analyzed. The mean proportion of adequate hand positioning was highest in V-DACPR with rapid transition (V-DACPR with rapid transition vs. C-DACPR: 92.7% vs. 82.4%, p = 0.03). The mean chest compression depth was deeper in both V-DACPR groups than in the C-DACPR group (V-DACPR with rapid transition vs. C-DACPR: 40.7 mm vs. 35.9 mm, p = 0.01, V-DACPR with delayed transition vs. C- DACPR: 40.9 mm vs. 35.9 mm, p = 0.01). Improvement in the proportion of adequate hand positioning was observed in the V-DACPR groups (r = 0.25, p < 0.01 for rapid transition and r = 0.19, p < 0.01 for delayed transition).

Conclusion: Participants in the V-DACPR groups performed higher quality chest compression with higher appropriate hand positioning and deeper compression depth compared to the C-DACPR group.

(C) 2021 Published by Elsevier Inc.

1. Introduction

Out-of-hospital cardiac arrest (OHCA) is a major public health prob- lem that is associated with high mortality [1,2]. Early bystander cardio- pulmonary resuscitation (CPR) is a key factor in the Chain of survival of OHCA [3,4]. To improve the rate of bystander CPR, dispatcher-assisted CPR (DACPR) programs have been implemented and are associated with increased bystander CPR rates and survival outcomes [5,6].

* Corresponding author at: Department of Emergency Medicine, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul, Republic of Korea.

E-mail addresses: [email protected] (S.G.W. Lee), [email protected] (T.H. Kim), [email protected] (H.S. Lee), [email protected] (S.D. Shin), [email protected] (K.J. Song), [email protected] (K.J. Hong), [email protected]

(J.H. Kim), [email protected] (Y.J. Park).

¹ Address: Seoul Metropolitan Government Seoul National University Boramae Medical Center, 20 Boramae-ro 5 Gil, Dongjak-gu, Seoul, 07061, South Korea

Although high-quality CPR is associated with favorable OHCA outcomes [7,8], previous studies showed that the quality of DACPR may be subop- timal and that the bystander may show poor compliance with the dispatcher’s instructions [9,10].

Conventional DACPR (C-DACPR) is usually based on audio calls be- tween dispatchers and callers. Audio calls do not provide visual infor- mation to the dispatcher; therefore, the dispatcher has limitations in providing feedback on bystander CPR performance. To overcome this limitation, video call DACPR (V-DACPR) has been suggested as an alter- native method [11,12].

Since most emergency calls are received as audio calls from the cal- lers to the dispatch center, dispatchers must convert the audio calls to video calls at a certain point to provide V-DACPR. Currently, no prior studies have evaluated the efficacy of V-DACPR using a standardized transition protocol from audio call, and most prior simulation trials compared CPR assisted on audio calls and CPR assisted on video calls

https://doi.org/10.1016/j.ajem.2021.01.049 0735-6757/(C) 2021 Published by Elsevier Inc.

not including the transition process between audio calls to video calls [12-16].

In this study, we validated the efficacy and safety of the newly devel- oped DACPR protocols with audio call to video call transition in a ran- domized simulation trial.

1. Materials and methods
   1. Study design

A randomized controlled simulation trial was designed to compare the quality of bystander CPR that was performed under three different dispatcher assisted protocols: C-DACPR, V-DACPR with rapid transition, and V-DACPR with delayed transition.

Seoul, the capital city of Korea, is a large metropolitan city with 10 million inhabitants and 3000 OHCAs per year. Seoul has a single and unified dispatch center that is operated by the Seoul Metropolitan Fire Department that is responsible for emergency medical service opera- tions for the whole city. A standardized C-DACPR protocol for cardiac ar- rest was implemented in 2011. If the dispatcher suspects the reason for the emergency call to be cardiac arrest, the dispatcher provides instruc- tions for chest compression-only CPR to the caller as soon as possible [5]. The Seoul dispatch center is capable of video calling, and V-DACPR has been available since 2017. However, due to technical issues, to per- form V-DACPR, the audio call from the caller must be hung up, and the dispatcher must make a new video call to the caller in order to perform V-DACPR.

• 1. Participants

Volunteers aged 18 years or older were recruited for the simulation trial from October 2019 to July 2020. Healthcare providers, and partici- pants with chronic lung diseases, cardiovascular diseases, visual disabil- ities, or hearing disabilities were excluded during initial enrollment. Written consent was obtained from all participants.

• 1. Randomization

After receiving standardized orientation about the study procedure, participants were randomized to one of three study groups: C-DACPR, V-DACPR with rapid transition, and V-DACPR with delayed transition. Randomization was performed by distributing computer generated ran- dom numbers to participants and then sorting the participant by the size of the distributed random number.

• 1. Simulation setting

Participants were guided to a separate room for the simulation ex- periment one at a time after randomization. The other participants stayed in a waiting room where they were not able to observe the ongo- ing simulation. Two dispatchers from the Seoul emergency dispatch center acted as a study dispatcher for the trial in a separate room.

Resusci Anne QCPR mannequin, which is supported with a skill reporting system (Laerdal, Stavanger, Norway) was set up to simulate a collapsed person. The study dispatcher’s mobile phone number was saved as 119, the Korean national emergency hotline equivalent to 911 or 999, in the study mobile phone before the simulation.

When entering the simulation room, the participant received a stan- dardized briefing of the scenario from a study assistant. The participant was told that he or she had come across a collapsed person and should call 119 using the study mobile phone presented by the study assistant. After briefing the scenario to the participant and presenting the study mobile phone, the study assistant was ordered not to assist or commu- nicate with the participant unless told to do so by the participant or the study dispatcher.

• 1. DACPR protocols

In the C-DACPR, the dispatcher uses a standard audio instructed protocol to help the participant initiate and perform chest compression-only CPR. The dispatcher informs the caller about correct chest compression posture, hand position, compression depth, and rate. The dispatcher uses an electronic metronome and counts the num- ber of compressions out loud to help the participant maintain an ade- quate compression rate while intermittently encouraging the participant to continue to perform chest compression at an adequate depth.

Two V-DACPR protocols were developed after several study meet- ings with the dispatch center and the research team. In both V-DACPR protocols, video call transition was performed after initiation of by- stander chest compression under the C-DACPR protocol to minimize possible delay to initiation of chest compression.

In the V-DACPR with rapid transition protocol, as soon as the dis- patcher confirms that the caller has initiated chest compressions, the dispatcher asks the caller if he or she was using a mobile phone capable of video call and if there was anyone around who could hold the caller’s mobile phone. If the answer to both questions is “yes”, the dispatcher in- structs the study participant to hand the mobile phone over to the per- son who could hold the mobile phone (a research assistant in simulation trial) and resume chest compressions. Then, the dispatcher notifies the caller that the dispatcher will hang up the phone and call- back with a video call. Before hanging up the call, the dispatcher empha- sizes that the caller should continue performing chest compressions without stopping during the video call transition process. When the dis- patcher is reconnected with a video call, the dispatcher instructs the as- sistant to face the camera to the front of the caller so that the study dispatcher can view the study participant performing chest compres- sions. If the caller’s chest compression posture or position is incorrect, the dispatcher instructs the participant to continue chest compression and to watch the mobile phone screen while performing chest compres- sion. The dispatcher shows the video call screen a video clip of standard chest compression and instructs the caller to perform chest compres- sion correctly. From the video, the dispatcher also evaluates the ade- quateness of chest compression depth and rate. The dispatcher gives feedback if needed, according to visual inspection.

In the V-DACPR with delayed transition group, most of the process is identical to the V-DACPR with rapid transition, except that the video call transition is initiated after the dispatcher counts 60 chest compressions with the caller. The study simulation protocols are briefly summarized in Fig. 1.

All scenarios were terminated 6 min after the emergency call, which is the average Ambulance response time in Seoul, and the study partic- ipants were told that the ambulance had arrived at the scene.

• 1. Data collection

The Quality of chest compressions performed by all participants was measured and collected by a mannequin with an accelerometer (Resusci Anne QCPR, Laerdal, Stavanger, Norway) The measurement pa- rameters, including chest compression rate, chest compression depth, No-flow time, and correct hand positioning, were extracted for analysis. Adequate chest compression was defined according to the American Heart Association and European Resuscitation Council guidelines as a chest compression rate between 100 and 120 compressions per minute, chest compression depth of more than 5 cm, and hand positioning on the lower half of the sternum [4,17]. No-flow time was defined as the in- terruption of chest compression for more than 1.5 s [18]. Total no-flow time was calculated by adding collapse-to-call time, call-to-first com- pression time, and cumulative chest compression interruption time.

Fig. 1. DACPR protocols. DACPR, dispatcher-assisted cardiopulmonary resuscitation.

• 1. Outcome measures

The main outcome of the study was the mean proportion of ade- quate hand positioning during chest compressions. The mean compres- sion depth, mean compression rate, and total no-flow time were compared between groups.

• 1. Statistical analysis and sample size calculation

Continuous variables were reported as means with standard devia- tions (SD) or medians with interquartile ranges (IQR). Categorical vari- ables were reported as numbers with percentages. Comparison of chest Compression quality was performed between groups using Student’s t- test or ?2 test as appropriate. Correlations between bystander CPR time and quality were tested with Pearson’s correlation coefficient. Statistical analysis was performed using Stata, Version 16 (StataCorp, College Station, TX).

Based on our previously conducted pilot study, the sample size was calculated to detect a 15% improvement in the mean proportion of ade- quate hand positioning in V-DACPR group compared with the C-DACPR group. Assuming a two-sided alpha of 0.05 and a power of 80%, the

estimated minimal sample size was 111 participants with 37 partici- pants per group.

• 1. Ethics statement

The study was approved by the institutional review board of the in- vestigators’ hospital (IRB No. 1906-021-1038). Informed consent was obtained from all participants.

1. Results

A total of 140 volunteers underwent randomization and performed the simulation trial. After excluding 9 simulation sessions with mechan- ical failure of data transmission, 43 participants were included in the C- DACPR group, 43 in the V-DACPR with rapid transition group, and 45 in the V-DACPR with delayed transition group (Fig. 2).

The demographics and overall chest compression performance of participants according to randomized group are shown in Table 1. There were no significant differences among age, sex, or CPR training experience, and call-to-first compression time be- tween groups. The mean proportion of adequate hand positioning

Fig. 2. Study flow. DACPR, dispatcher-assisted cardiopulmonary resuscitation.

during chest compression was higher in both V-DACPR groups than in the C-DACPR group (V-DACPR with rapid transition vs. C-DACPR: 92.7% vs. 82.4% p = 0.03, V-DACPR with delayed transi- tion vs. C-DACPR: 91.1% vs. 82.4% p = 0.07). The mean chest com- pression depth was significantly deeper in both V-DACPR groups then in the C-DACPR group (V-DACPR with rapid transition vs. C-DACPR: 40.7 mm vs. 35.9 mm, p = 0.01, V-DACPR with delayed transition vs. C-DACPR: 40.9 mm vs. 35.9 mm, p = 0.01). There were no statistically significant differences in the mean proportion of adequate hand position, mean compression depth, or mean compression rate between V-DACPR with rapid transition and V-DACPR with delayed transition groups.

The CPR performance of participants from the C-DACPR protocol (n = 43) and participants from the overall V-DACPR (regardless of rapid or delayed transition, n = 88) is summarized in Table 2. Partici- pants in the overall V-DACPR group had a higher mean proportion of

adequate hand positioning and deeper mean compression depth compared to the C-DACPR group (91.9% vs. 82.4% p = 0.02, 40.8 mm vs. 35.9 mm, p < 0.01, respectively). There were no statistically signifi- cant differences in total no-flow time between the C-DACPR and the V-DACPR (22.6 s vs. 19.8 s, p = 0.33).

Fig. 3 shows the change in mean compression depth over time. A decrease in the mean compression depth was observed in the C-DACPR group over time (r = -0.22, P < 0.01), whereas no significant change was observed in the V-DACPR with rapid transition (r = -0.05, p = 0.52) or delayed transition groups (r = -0.12, p = 0.08).

Fig. 4 shows the change in mean proportion of adequate hand positioning over bystander CPR time. Improvement in the proportion of adequate hand positioning was observed in the V-DACPR with rapid transition (r = 0.25, p < 0.01) and delayed transition groups (r = 0.19, p < 0.01), whereas no significant change was observed over time in the C-DACPR group (r = -0.01, p = 0.98).

Table 1

Comparison of simulation results according to DACPR protocols

Total (1) C-DACPR (2) V-DACPR

with

rapid transition

(3) V-DACPR

with delayed transition

p-value

	Mean	SD	Mean	SD		Mean	SD		Mean	SD		((1) vs. (2))	((1) vs. (3))	((2) vs. (3))
Number of participants	131		43			43			45
Age (years)
mean, SD	30.1	11.4	30.8	12.1		30.5	12.0		29.1	10.2		0.55	0.76	0.72
median, IQR	25.5	21-37	26.5	21-37		25	21-37		25	21-34		0.99	0.80	0.71
Sex
Male (n, %)	30	22.9	9	20.9		10	23.3		11	24.4		0.80	0.69	0.90
CPR training experience
Any training experience (n, %)	94	71.8	32	74.4	30		69.8	32		71.1	0.63		0.73	0.89
CPR training within recent 2 years (n, %)	57	43.5	19	44.2	20		46.5	18		40.0	0.83		0.69	0.54
Total compression time (seconds)	286.8	20.0	285.8	18.8	286.9		25.8	287.6		14.4	0.41		0.31	0.44
Time from call-to-first chest compression
mean, SD	72.3	19.3	72.8	17.1	72.3		25.3	71.9		14.4	0.91		0.79	0.93
Time from call start to video call transition
mean, SD	153.0	32.2	N/A	N/A	141.9		28.4	163.5		32.4	N/A		N/A	<0.01
Total no-flow time (seconds)	20.7	32.9	22.6	45.9	18.9		16.0	20.6		30.6	0.69		0.59	0.37
Mean compression depth(mm)	39.2	9.7	35.9	10.2	40.7		9.7	40.9		8.4	0.01		0.01	0.47
Proportion of compressions with adequate depth (%)	19.9	30.6	13.9	27.5	24.1		32.5	21.7		31.3	0.06		0.11	0.64
Mean compression rate (per min)	109.7	9.3	10.7.2	9.5	111.8		10.8	110.2		6.9	0.02		0.05	0.80
Proportion of compressions with adequate rate (%)	89.2	14.6	88.9	18.3	87.8		14.2	90.7		10.5	0.61		0.28	0.14
Mean proportion of adequate position (%)	88.8	23.8	82.4	33.7	92.7		13.0	91.1		19.2	0.03		0.07	0.68

CPR, cardiopulmonary resuscitation; C-DACPR, conventional dispatcher-assisted cardiopulmonary resuscitation; V-DACPR, video call dispatcher-assisted cardiopulmonary resuscitation; SD, standard deviation; IQR, interquartile range

Table 2

Comparison of simulation results between C-DACPR and V-DACPR

C-DACPR V-DACPR p-value

Mean SD Mean SD

Number of participants 43 88

Age (years) Mean, SD	30.8	12.1	29.8	11.1	0.32	call due to technical issues. No prior studies have evaluated standard-
Median, IQR	26.5	21-37	25.0	21-34.5	0.89	ized protocols for this process. Our study developed two standardized

CPR, lack of training, old age, panicking, and instruction misunderstand- ing [9,10]. V-DACPR enables the dispatcher to watch the bystander performing CPR and give Real-time feedback to the caller.

Witnesses of an emergency usually audio calls the emergency hot- line. To convert from audio to video call, after responding to the emer- gency audio call the dispatcher must hang up and call back with video

Sex

Male (n, %)	9	20.9	21	23.9	0.71
CPR training experience
Any training experience (n, %)	32	74.4	62	70.5	0.64
CPR training within recent 2 years	19	44.2	38	43.2	0.91
(n, %)
Total compression time (seconds)	285.9	18.8	287.3	20.7	0.35
Total no-flow time (seconds)	22.6	45.9	19.8	24.4	0.33
Mean compression depth(mm)	35.9	10.2	40.8	9.1	<0.01
Proportion of compressions with	13.9	27.5	22.9	31.7	0.06
adequate depth (%)
Mean compression rate (per min)	107.2	9.5	111.0	9.0	0.02
Proportion of compressions with	88.9	18.3	89.3	12.5	0.43
adequate rate (%) Mean proportion of adequate position	82.4	33.7	91.9	16.4	0.02
(%)

CPR, cardiopulmonary resuscitation; C-DACPR, conventional dispatcher-assisted cardio- pulmonary resuscitation; V-DACPR, video call dispatcher-assisted cardiopulmonary resus- citation; SD, standard deviation; IQR, interquartile range

1. Discussion

The efficacy of the video-assisted dispatcher CPR transition protocol was evaluated in a randomized controlled simulation trial. Overall im- provement in chest compression quality was observed in the V-DACPR groups regardless of transition time when standardized protocols were implemented. The results of our study showed that V-DACPR could be implemented safely under the current dispatching system by transitioning audio calls to video calls using a controlled protocol and that the caller could perform better quality bystander CPR by receiving real-time feedback from the dispatcher.

C-DACPR has been utilized to help the lay person perform CPR and is known to improve the rate of bystander CPR [5,6,19-21]. However, there is a limitation in the efficacy of C-DACPR because of poor compli- ance with dispatcher instructions due to factors such as inexperience in

V-DACPR protocols including audio to video call transition.

In our study the mean proportion of adequate hand positioning was significantly higher in the V-DACPR groups than in the C-DACPR group. Similar results have been observed in prior studies by Lee et al. and Stiuplante et al. [14,15,22]. The simulation study by Yang et al. did not show improvement in hand positioning when V-DACPR was imple- mented and proposed that an optimal viewpoint to assess adequate hand positioning was needed [13]. Our study overcame this limitation by instructing the assistant to show the study participant from the front and by giving an additional view that was focused on the participant’s hand position.

As observed in prior studies, the mean compression depth was sig- nificantly deeper in the V-DACPR groups than in the C-DACPR group [13-15]. However, when the proportion of compressions with adequate depth was compared between the C-DACPR and V-DACPR groups, no statistically significant difference was observed. This may be attributed to the overall inadequate depth of compression in both the C-DACPR and V-DACPR groups and the small population size. A low proportion of compression with adequate depth in both the C-DACPR and V- DACPR groups has been observed in previous studies [13,14,16,22]. The objective of dispatcher assistance during bystander CPR is to help the lay person perform CPR. Our study participants were nonprofes- sionals, and thus the depth of chest compressions may have been sub- optimal. Considering that the proportion of compressions with adequate depth was low in both in the C-DACPR and V-DACPR groups, the dispatcher should emphasize pressing deeper when giving instructions.

Although the rate of chest compression was significantly higher in the V-DACPR groups, the proportion of chest compression within the optimal rate was not significantly different. This result suggests that the metronome and counting numbers by the dispatcher in the C- DACPR protocol are Effective interventions in terms of maintaining an adequate rate of chest compressions.

Fig. 3. Change in mean compression depth over time. C-DACPR, conventional dispatcher-assisted cardiopulmonary resuscitation; V-DACPR, video call dispatcher-assisted cardiopulmonary resuscitation.

Fig. 4. Change in mean proportion of adequate hand position over time. C-DACPR, conventional dispatcher-assisted cardiopulmonary resuscitation; V-DACPR, video call dispatcher- assisted cardiopulmonary resuscitation.

The mean proportion of adequate hand compression increased over time in the V-DACPR group while no change was observed in the C- DACPR group (Fig. 4). The visual evaluation of chest compression posi- tion followed by direct feedback to the rescuer by the dispatcher through the video call could contribute to the improvement in the V- DACPR group. The depth of compression over time remained constant in the V-DACPR groups compared to the decrease in depth in the C- DACPR group (Fig. 3). Chest compression quality is known to decay over time from initiation of bystander CPR due to fatigue [23,24]. The finding suggests that the chronological decay of chest compression quality can be improved with V-DACPR.

In contrast to previous studies where a significant delay to the start of chest compression was observed in video call assisted groups, our study did not show a significant difference in call-to-first compression time between the C-DACPR and V-DACPR groups [13,14]. An increase in no-flow time and interruption of chest compression, has a negative impact on survival in OHCA patients [18,25,26]. Although controversial, studies have shown concerns that V-DACPR could cause an increase in no-flow time [13,14,16,22]. In our study, no-flow time was not in- creased in the V-DACPR group compared to the C-DACPR group. This discrepancy could be due to the implementation of a standardized tran- sition protocol in which the participant starts chest compression with audio-assistance followed by audio-to-video transition by an assistant, whereas in other studies, participants in the V-DACPR groups started video calls without preceding audio calls. These findings suggest that V-DACPR with audio-to-video transition does not delay time to first compression or increase no-flow time when standardized protocols are used.

1. Limitations

This study is a simulation trial conducted with a mannequin and cannot replace real-life cardiac arrest. In real-life the bystander may not be as compliant to the dispatcher as in the study due to fear and anx- iety [9,27,28]. In addition, an assistant may not be available on scene and even when available the assistant may not be able to adequately follow the dispatcher’s instruction. Further real-life studies with standardized protocols are needed.

The discontinuation of the audio call to change to video call has the risk of losing connection between the dispatcher and bystander. Al- though audio to video call transition can be performed without

discontinuation of the phone call between mobile phones, the dispatch center in Seoul cannot directly change from audio to video call without discontinuing the phone call. Technological improvement to enable di- rect transition from audio to video calls could help dispatchers assist by- standers in performing CPR. Finally, in our trial, one of the researchers acted as a bystander holding the mobile phone for the caller during V- DACPR. The ability to hold the mobile phone for an appropriate video call view could be different according to the bystanders in real situa- tions. Future studies should be considered regarding the compliance and appropriateness of bystanders holding the mobile phone according to the dispatcher’s instructions.

1. Conclusions

New DACPR protocols with audio call-to-video call transition were developed. The protocols were shown to be safe and to effectively im- prove the quality of bystander CPR in a randomized simulation trial. Local medical directors should consider developing protocols that incor- porate video calls and visual feedback into each dispatch center system for high-quality bystander CPR.

Declaration of Competing Interest

None

Acknowledgements

None

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