a b s t r a c t

Purpose: The aim of this study was to compare on manikin chest compressions only CPR performance carried out by untrained volunteers following Dispatcher assisted Cardiopulmonary Resuscitation (DACPR), and then by the same trained volunteers immediately after chest compressions only CPR course and 4 months after the CPR course.

Method: 38 university student volunteers with no previous experience in CPR took part in three on manikin chest compressions only CPR skill evaluations: first in a DACPR, then after chest compressions only CPR course (ACPRC) and lastly, four months after a CPR course (4MACPRC). Only 22 completed the whole process.

Results: In DACPR 7.89% of participants carried out cardiac compressions outside the thorax. The mean average time from collapse to first compression was reduced in 4MACPRC (40.77 s), as compared to DACPR (144.54 s); p b 0.001).

The following parameters were significantly better in 4MACPRC than in DACPR: Average compression depth (44.72 vs 25.22; p b 0.001), average compression rate (106.1 vs 87.90; p b 0.001), total number of compressions in 3 min (317 vs 245; p b 0.001), percentage of correct compressions (53.00% vs 4.72 %; p b 0.001) and percentage of correct hand positioning (95.40 vs 91.09; p b 0.001).

Conclusions: Even though chest compressions only DACPR allows lay bystanders to be able to carry out cardiac compressions in 92.1% of cases, these were delivered later and were less efficient than chest compressions only CPR given by trained bystanders after a CPR course and four months after the course.

(C) 2016

Introduction

Sudden cardiac arrest is one of the main causes of death worldwide; in Europe, between 350,000 and 700,000 people die every year [1-4]. Early recognition and a prompt initiation of bystander Car- diopulmonary Resuscitation CPR are critical for successful defibrillation [5-8] and to improve the outcome, thus doubling or quadrupling a victim’s chances of survival [9-12].

The rate of bystander CPR varies greatly among communities from 10% to 65% [13]. To improve this situation in the early 1970s, the idea of Dispatcher-assisted CPR (DACPR) or telephone CPR was first con- ceived [14]. International Guidelines for Resuscitation 2015 [15]

* Corresponding author at: University of Santiago de Compostela, Campus de Lugo, CP: 27001 Lugo, Spain.

E-mail address: [email protected] (R. Navarro-Paton).

recommend DACPR because it improves bystander CPR rates [16-20], increases the number of chest compressions delivered [20] and im- proves patient outcomes following out-of hospital cardiac arrest (OHCA) [6-9,15,21-23]. Recent studies [24,25] relate a higher survival to hospital discharge rate and higher favorable functional outcome rate after the implementation of a telephone CPR program and DACPR outcomes are comparable to those of presumably trained bystander CPR without assistance [26,27], even improving neurological recovery at discharge in adults and children aged older than 8, especially in OHCA in private settings.

Previous manikin studies [28,29] delivering both ventilations and compressions relate that DACPR with previously untrained volunteers performed CPR of an overall quality comparable to that performed by previously trained bystanders, but this may have changed with the new adult guidelines with chest-compressions-only DACPR and the supposed better recall results of teaching a single skill in a chest com- pression only CPR course instead of standard CPR.

http://dx.doi.org/10.1016/j.ajem.2016.12.014

0735-6757/(C) 2016

The aim of this study was to compare on manikin chest compres- sions only CPR performance carried out by untrained volunteers follow- ing DACPR instructions, their performance immediately after chest compressions only CPR course and then 4 months after CPR course.

Methods

Participants

The participants were students from Santiago de Compostela Uni- versity (Spain) who had received no prior CPR training. They volunteered for the study, were provided with information on the study and written consent was obtained. The study was approved by the Santiago de Compostela University Ethics Committee.

Pre-assessment

An ad hoc questionnaire was initially administered to find out the socio-demographic details and previous knowledge of BLS, eliminating those who had received previous formation or training in Cardiopulmo- nary Resuscitation.

Each participant in this study served as his/her own control and the whole experience was composed of a DACPR simulation, chest com- pressions only CPR course and three CPR skill evaluations: DACPR prior to training, then immediately after CPR course and finally 4 months after the course as a part of a long-term follow-up evaluation in order to compare skill improvement or deterioration. DACPR was included as

part of the CPR course in order for students to gain confidence, and be aware of the fact that they could always request dispatcher CPR assistance.

The evaluations and times were recorded. Two CPR experts evaluat- ed the whole process in real time following a check list.

The CPR manikin used for performance and data gathering was the Laerdal Resusci Anne manikin with the Skill reporter software version

2.4; Laerdal medical AS, Norway, programmed for chest compressions only CPR.

The whole process was carried out according to the current [15] recommendations.

Assessment

DACPR procedure as part of the initial CPR course

The participants were individually invited into an isolated room and were explained that it was an on manikin simulated situation in which they witnessed someone passing out and falling to the floor; they were provided with a smartphone, told how to dial the emergency medical services number (061) which correspond to the FPUS Galicia, Emergen- cy Medical Service Central Dispatching, and were requested to do so in real time. The call was answered by an operator who was informed of the location of the incident, classified the call and transferred it to a co- ordinating doctor who confirmed the status of the call and guided 3 min of chest compressions only CPR telephonically following the National Consensus on Dispatcher assisted CPR based on ERC Guidelines [30] (Fig. 1).

Fig. 1. Guide to identifying CA and application of CPR in adults.

CPR course

Just after the DACPR procedure a chest compression only CPR course was given to the students. Immediately after the course the second CPR skills evaluation was done with the same characteristics as the first. Car- diac compressions only CPR course was chosen instead of a convention- al CPR course to better compare results with DACPR performance.

CPR skills evaluation four months after CPR course (4MACPRC)

Four months after the CPR course a new CPR skills evaluation took place following the same procedure. This time interval was chosen with the aim of comparing CPR skill deterioration over time and most studies show that CPR skills decay within 3 to 6 months after initial training [31].

Data collection

The details collected in the questionnaire included the participants’ sex and age.

The assessor’s observations (Table 1) were written down on an ob- servation form with dichotomous responses (Yes-No or Correct-Incor- rect) and were evaluated in the DACPR and in 4MACPRC.

The manikin program collected average compression depth (CoD), compression rate (CoR), chest recoil percentage (ChR), total number of compressions (TCoN), percentage of correct compressions (CCo) and correct hand positioning (CHP) (chest compression point) on three different occasions, DACPR prior to course (M0), immediately after the CPR course (M1) and 4MACPR (M2).

The interval of time between collapse - start of cardiac compressions was registered.

Data analysis

Continuous variables were summarized by the mean and standard deviation (SD) and the 3 performances (M0, M1, M2) were then compared.

Statistical analysis was completed with SPSS for Windows, version 20 (SPSS Inc, IBM, USA). The significance of difference was set at the p b 0.05 level (CI 95%). The Shapiro-Wilk test was carried out for the normality study. The repeated ANOVA measures test with Bonferroni correction was used to analyze dependent variables. Pearson’s Chi- squared test was used to evaluate the differences between groups.

Results

Participant demographics and follow up

38 individuals, between the ages of 19 and 26 (M = 20.68; SD = 1.61), were included in the DACPR procedure. During the initial

Table 1

Results for the descriptive analysis of the variables analyzed. Assessor’s observations.

DACPR evaluation three participants were not able to deliver cardiac compressions: two participants delivered the compressions outside of the thorax (1 in the abdomen and 1 in the neck) and the other one did not compress but massaged.

The remaining 35 participants (92.1%) carried out compressions on the thorax, but 1 of these cases was not recorded due to technical prob- lems and so was excluded.

Only 22 out of the 35 participants, 8 males (36.36%) and 14 females (63.63%) completed the whole process. In the 4MACPRC evaluation none of the participants asked for the dispatcher’s CPR guidance (Fig. 2).

Average time from collapse to start of cardiac compressions

The average time from collapse to first compression was significant- ly reduced in M2 (4MACPRC) compared to M0 (DACPR): mean 40.77 s (SD = 7.63 s) vs 144.54 s (SD = 35.41 s); p b 0.001).

Assessor’s observations

The observed results can be seen in Table 1. Statistically significant differences were found between both Moments M0 and M2 in: con- sciousness evaluation (p b 0.001); Breathing evaluation (p b 0.001); Clothing removal (p b 0.001); Hand placement (p = 0.003). No statisti- cal differences were found in the Rescuer’s position (p = 0.550).

	Moment
		DACPR (M0) n = 22	4MACPRC (M2) n = 22
Consciousness evaluation	No	21 (95.5%)	5 (22.7%)
	Yes	1 (4.5%)	17 (77.3%)
Breathing evaluation	No	18 (81.8%)	3 (18.2%)
	Yes	4 (13.6%)	19 (86.4%)
Rescuer’s position	Incorrect	1 (4.5%)	2 (9.1%)
	Correct	21 (95.5%)	20 (90.9%)
Clothing removal	No	22 (100.0%)	4 (18.2%)
	Yes	0 (0.0%)	18(81.2%)
Hand placement	Incorrect	11 (50.0%)	2 (9.1%)
	Correct	11 (50.0%)	20 (90.9%)

DACPR: Dispatch Assisted Cardiopulmonary Resuscitation; M0: Initial Moment data col- lection; 4MACPRC: 4 Months After Cardiopulmonary Resuscitation Course; M2: 4MACPRC

data collection. Fig. 2. Flow diagram of participants’ eligibility.

Table 2

Descriptive statistical manikin’s CPR parameters collected.

Variable M0

(n = 22)

Mean SD Maximum Minimum

M1

(n = 22)

Mean SD Maximum Minimum

M2

(n = 22)

Mean SD Maximum Minimum

CoD (mm)	25.22	10.56	53 11	42.54	10.82	59 25	44.72	11.95	61 19
CoR (c-m-1)	87.90	15.12	123 68	116.45	11.07	135 97	106.18	17.77	150 76
ChR (%)	83.00	29.76	100 2	64.81	37.64	100 0	73.18	34.77	100 3
TCoN (3 min)	245.59	58.87	365 113	349.18	32.49	401 291	317.50	48.15	412 317
CCo (%)	4.72	19.27	90 0	35.40	41.31	100 0	53.00	33.03	98 0
CHP (%)	91.09	24.28	100 5	82.27	33.40	100 1	95.40	18.83	100 12

M0: Dispatch Assisted Cardiopulmonary Resuscitation data; M1: after CPR course recollected data; M2: Four Months After Cardiopulmonary Resuscitation Course; n: Number of partic- ipants; CoD: Average compression depth; CoR: Compression rate; ChR: Chest recoil percentage; TCoN: Total number of compressions; CCo: Percentage of correct compressions; CHP: Cor- rect hand positioning (CHP) (chest compression point).

Manikin’s CPR parameters collected

The Manikin’s parameters can be seen in Table 2.

Statistically significant differences were found in the following pa- rameters from among the three evaluations: CoD: M0 = 25.22 mm, M1 = 42.54 mm, M2 = 44.72 mm (p b 0,001; Eta² p = 0,698); CoR : M0 = 87.90, M1 = 116.45, M2 = 106.18 (p b 0,001; Eta² p = 0,566); TCoN: M0 = 245.59, M1 = 349.18 , M2 = 317.50 (p b 0,001; Eta² p = 0,657); CHP: M0 = 91.09% , M1 = 82.27%, M2 = 95.40% (p b 0,001; Eta² p = 0,671); CCo, M0 = 4.72 %, M1 = 35.40%, M2 = 53.00% (p b 0,001; Eta² p= 0,686).

Discussion

Unlike previous on manikin simulations involving rescue breathing in addition to chest compressions, the present study of chest compres- sions only CPR shows that CPR performed by basic life support trained bystanders achieves better results than DACPR.

Cardiac compressions were not carried out in almost 8% of cases in the DACPR group because they were delivered outside the chest or as a soft massage and the DACPR efforts were useless. According to current guidelines [15] the recommendation “place the heel of your hand in the center of the chest with the other hand on top” was given to the partic- ipants. Some studies reinforce the importance of the exact location of the compressions point [37] and how it could be improved, like advice to find the point between the nipples [38] or to palpate the Suprasternal notch (SN) and place the dominant heel of the hand one Heel width from SN [39]. The percentage of failed CPR should be added to the refus- al by bystanders to carry out CPR, which can record rates of up to 12% in a real life arrest setting [19].

Cardiac compressions were started 105 s later in DACPR than in 4MACPRC. The DACPR collapse to compressions time, nearly 2 1/2 min, is consistent with other simulation studies [32] but in other on manikin [28,33] and real situation studies this time increases [20,26, 27] and can exceed 5 min [34].

The following of CPR steps in the detection of CA was significantly worse in the DACPR experience than in the 4MACPRC, which coincides with some studies on real patients which estimate that CA detection by the dispatcher is around 43% [22].

On manikin CPR performance was significantly better in the 4MACPRC than in the DACPR: Average compression depth significantly improved 19.5 mm from DACPR to 4MACPRC: only 4.72% of the partic- ipants in the DACPR reached a compression depth of 50 mm as com- pared to 53% in 4MACPRC. As the performance of the participants was

suboptimal according to some CPR studies, the results might have been improved if it had been recommended to compress with the dom- inant hand [40] and on the same side of the victim as the dominant hand [41]. Interestingly, the depth was significantly better in 4MACPRC than immediately after the CPR course, probably due to the fatigue caused by nearly two hours of cardiac compression training.

The compression rate was significantly lower in the DACPR than in the 4MACPRC, in this last experience the average rate reached CPR Guideline recommended parameters. To improve this low DACPR com- pression rate, a newly designed bundle of care protocol could be used [35,36].

The average total compression number was also significantly better in the 4MACPRC than in DACPR.

Chest recoil was adequate in DACPR and was not significantly better than in 4MACPRC, probably due to the shallowness of the compressions and the low frequency of the massage [23].

This on manikin study shows that DACPR increases the time to first compression, and CPR performance is not as good as chest compressions only CPR with previous training. DACPR increases the number of actions taken with respect to the absence of bystander CPR, and can also be used to refresh the competence of previously trained lay bystanders in the likelihood they witness an OHCA but it should not substitute CPR train- ing courses.

Conclusions

Unlike other previous ventilation and compression CPR on manikin studies, the results of the present study show that chest compressions only CPR trained bystanders perform cardiac compressions sooner and better than untrained bystander DACPR.

Limitations

The main limitation is the simulation: by considering the situation with a manikin, the real patient is probably not being represented. Be- cause the study was designed to compare different moments in the long-term follow-up of individual CPR performance, no randomization was planned and the mean age of the participants, mostly women, does not accurately represent the most likely OHCA witness, the spouse of an elderly victim at home [38]. Because of the difficulty in completing the whole process, the sample size was reduced. It is known that CPR skills deteriorate within months [31], the study chose 4 months but op- timal training intervals are unknown. We don’t know if repeated calls to the EMS (emergency services) call center generated a quicker response, or if the doctor’s guidance improved due to repetition [29].

Acknowledgements

Lugo Medical Association.

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