I．Introduction

There are about 2,000 cases of pediatric out-ofhospital cardiac arrests（OHCA）in all over Japan every yea^［1］. Almost half of them have been happening in infant age group, less than 1 year old. Infant OHCA usually occur at home or in nursery school. Thus, adequate training in infant basic life support（BLS）for parents and nursery school teachers is an important component of infants’ safety training program at home and nursery school. Barriers to traditional in-classroom cardiopulmonary resuscitation（CPR）training programs include time away from home and work place to complete training, learner discomfort over being in a classroom setting, and instructors who include information irrelevant to CPR, and logistics ^［2］.

Self-directed CPR learning（SDL）kit for BLS was developed and it demonstrated equal learning outcomes comparable to those obtained with traditional instructorled courses and is a more time efficient tool for CPR training including automated external defibrillator（AED）. Furthermore, the SDL kit overcomes many of the barriers that keep individuals from learning CPR and appears to contribute to bystanders’ confide ntly attempting CPR ^［2-5］.

It was only for adult CPR previously, however, SDL kit for infant BLS was developed and translated into Japanese recently. This study evaluated the effectiveness of SDL kit in lay rescuers on infant BLS.

II．Subjects and methods

A total of 10 nursery school teachers were involved in this study after informed consent. Performance of infant BLS was measured by the specialized manikin（Resusci Baby QCPR^TM and SimPad^TM, Laerdal Medical Japan Co., Ltd）. Infant BLS was performed for two minutes pre-learning and post-learning respectively. Infant BLS learning was done for about 20 minutes by SDL kit（MiniBaby^TM, Laerdal Medical Japan Co., Ltd）.

Performance of infant BLS was measured and evaluated using several parameters, such as chest compression（CC）depth, adequate CC location, CC interruption, CC numbers（/session, /minute）, rescue breath（RB）tidal volume（TV）, RB numbers（/session, /minute）, and total performance score. Data was analyzed comparing pre-learning and post-learning on CC depth and RBTV. P value less then 0.05 means statistical significance and less then 0.1 means tendency.

This study was approved by the ethics board of the Medical Research Committee of Tokyo Metropolitan Children’s Medical Centre（TMCMC）. Publication of the study was approved by the Institutional Review Board of TMCMC.

III．Results

Total of 10 nursery school teachers performed infant BLS sessions pre and post-learning. Measured parameters were indicated in Table. 1. Session length was 2 minutes and CC vs. RB ratio was 30 : 2. Targeted CC depth and RBTV were set at 40 mm and 100 ml respectively. Desired CC tempo per minute（numbers/ min）was 100-120/min. More CC interruption（second） and less CC fraction（%）led less CC numbers/session. Desired RB numbers were 10/session and 5/minute.

There were no statistical significance in improvement of CC depth, RBTV and other parameters, however, tendency of improvement of CC depth after self-directed learning of infant BLS was shown in Figure 1（p＜0.1）.

There were several rescuers who were not able to achieve RB before this learning process（n＝5, rescuer# 1-5）. Statistical significance of improvement of RBTV in this subgroup after self-directed learning of infant BLS was shown in Figure 2（p＜0.05）.

IV．Discussion

In the guidelines of Japanese Resuscitation Council （JRC）, BLS for adults and that for children are united and simplified into one algorithm basically ^［6］. Although BLS for infants is still within this single JRCBLS algorithm, RB is more emphasized for infants because infant OHCA is often caused by respiratory pathophysiology ^［7］

SDL kit gave us paradigm shift in BLS training. It made the training time period shorter, increased manikin vs. learner ratio and gained actual practice time per learner using manikin, saving costs and human resources for education, produced possibility to multiply learners at home and gave chance to repeat training, and importantly, kept equal learning outcomes comparable to those obtained with traditional instructor-led courses.

During the BLS training, RB part is more difficult to improve comparing to CC. It is more obvious in infant BLS training, though RB is more important in infant BLS. Previous studies showing SDL kit efficacy used adult manikin and were not particularly indicating the specific efficacy of RB skill improvement in infant BLS ^［2-5］. In this study, half of the rescuers could not perform RB at all before learning. Significant improvement of RB for this particular subgroup brought by this infant BLS SDL kit is thought to be very impressive efficacy.

This study has several limitations, such as low number of materials, only for lay rescuers, no information of skill retention, no information of previous experience of BLS training or practice, etc. Efficacy of this SDL kit for infant BLS using bag valve mask ventilation performance by health care providers, such as nurses and residents, should be investigated further. Skill retention is another important parameter need to be studied. Additionally, new CPR feedback application is recently investigated（iCPR）^［8］. The combination of SDL kit learning and practice with iCPR feedback would be another target of research in near future.

Contributors

NS conceived and designed the study, collected, analyzed, and interpreted the data. NS, TI, MN, and KO were involved in writing and reviewing the manuscript.

Acknowledgements

I would like to thank Mr. James Robert Valera for his assistance with editing the manuscript.

Conflict of interest

The authors declare that they have no conflicts of interest, either financial or non-financial, with the context of this article, except for the public grant from Tokyo Metropolitan.