Original Contribution
What biomechanical factors are more important in compression depth for children lifesavers? A randomized crossover study

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Abstract

Objective

To evaluate the biomechanical aspects involved in Cardiopulmonary Resuscitation's compression depth by children.

Methods

A randomized crossover study with 196 children between 9 and 14 years-old was conducted. The children performed four CPR hands-only tests of 1 min in four different heights (floor, 5 cm, 10 cm, and 15 cm). Anthropometric, angulation and quality of CPR variables were registered during the tests.

Results

CPR quality was sub-optimal in all tests. Tests with the simulated victim placed on the floor had the best compression quality. Children that made deeper compressions had significantly higher values in all anthropometric variables. Analysis gives more discriminatory power to the anthropometric variables than angulation variables on compression depth.

Conclusion

Chest compression depth obtained by children depends more on their anthropometric characteristics than on their body position. The approximate age to perform compressions with an acceptable quality is 12 years-old. The use of steps increased arm angle, getting it closer to 90° but did not increase quality CPR when compared with performance on the floor.

Introduction

Cardiac arrest is one of the leading causes of death in developed countries [1]. Bystander CPR has the potential to improve outcomes [2,3]. One possibility to improve this might be to implement a basic life support (BLS) program at schools. Some evidence shows that implementing a BLS program at school increased the percentages of resuscitation attempts made by witnesses in future years [[4], [5], [6]]. Maybe “Kids save lives” would be the way to improve outcomes in cases of Out-of-Hospital Cardiac Arrest (OHCA) [7,8]. Teaching BLS at school has several advantages, with positive pedagogical connotation and with a positive cost-benefit relationship [9,10].

In recent years, several studies have pointed towards age as an important factor for QCPR in children as lifesavers. These studies suggest that 12–13 years-old is the approximate age to perform CPR with an acceptable quality from a physical and cognitive point of view [7,[11], [12], [13], [14], [15]]. Multiple studies point out the importance of variables such as body mass index (BMI) and physical fitness [16,17], weight [18,19], and other anthropometric variables like length of the forearm and femur [20].

In ERC 2015 guidelines, emphasis is placed on arm positioning, vertically straight over the victim's chest [21]. One study found rescuers perform better QCPR when chest compressions are done with a 90-degree arm angle over the victims' chest compared with less than a 90-degree arm angle [22]. Moreover, several studies have found an improvement in quality when using a step to perform CPR on a stretcher [20,22,23].

Therefore, the aim of this study was to evaluate the different biomechanical factors involved in compression depth of CPR performed by children. In addition, the differences in angulation and CPR quality depending on the elevation with children were analyzed.

Section snippets

Participants

A total of 196 children (125 girls and 71 boys) in the city of Pontevedra (Spain) were included in the study. Ages of these kids ranged from 9 to 14 years-old. Inclusion criteria were: voluntary participation, parental authorization, written consent and to complete all phases of the study. Excluding criteria were: physical limitations not compatible with performing the CPR and no consent from their parents. None of the participants had previous CPR experience.

Design

A crossover randomized

Results

The age of the participants was: 9 years-old (20.9%), 10 years-old (16.3%), 11 years-old (23.5%), 12 years-old (18.9%), 13 years-old (16.3%) and 14 years-old (4.1%). The anthropometric variables of the whole sample were: Age (11.06 ± 1.50 years-old), Height (148.90 ± 10.01 cm), Forearm length (22.43 ± 1.66 cm), Arm length (48.77 ± 3.74 cm), Femur length (41.27 ± 3.97 cm), Weight (44.15 ± 10.47 kg) and BMI (19.73 ± 3.23 kg/m2). Anthropometric data of participants are shown in Online Table 1.

Discussion

Children are a key target for CPR training [8,11,33]. Previous studies suggest 9–10 years-old as the approximate age when children can learn to perform CPR and retain that knowledge [34,35]. However, due to their physical characteristics, scientific evidence points out that the age to perform CPR with an acceptable quality is 12–13 years-old [7,[11], [12], [13], [14], [15]]. This study analyzed the influence of children's body parameters and elevation on CPR quality.

The results obtained suggest

Conclusions

The results obtained in this study show a sub-optimal CPR quality in all step heights tested. The use of steps increased arm's angle, getting it closer to 90°. However, to use steps in children does not increase CPR quality since on the floor. Finally, data show that compression depth by children depends on anthropometric characteristics, with 12-year-old being the approximate age for having an acceptable CPR quality. Children perform a sub-optimal CPR quality due to their physical

Conflicts of interest

The authors of this study declare that they not to have any conflict of interest, either personal or financial, in relation with this research.

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