Elsevier

Resuscitation

Volume 84, Issue 5, May 2013, Pages 666-671
Resuscitation

Simulation and education
Does a more “physiological” infant manikin design effect chest compression quality and create a potential for thoracic over-compression during simulated infant CPR?

https://doi.org/10.1016/j.resuscitation.2012.10.005Get rights and content

Abstract

Poor survivability following infant cardiac arrest has been attributed to poor quality chest compressions. Current infant CPR manikins, used to teach and revise chest compression technique, appear to limit maximum compression depths (CDmax) to 40 mm. This study evaluates the effect of a more “physiological” CDmax on chest compression quality and assesses whether proposed injury risk thresholds are exceeded by thoracic over-compression.

A commercially available infant CPR manikin was instrumented to record chest compressions and modified to enable compression depths of 40 mm (original; CDmax40) and 56 mm (the internal thoracic depth of a three-month-old male infant; CDmax56). Forty certified European Paediatric Life Support instructors performed two-thumb (TT) and two-finger (TF) chest compressions at both CDmax settings in a randomised crossover sequence. Chest compression performance was compared to recommended targets and compression depths were compared to a proposed thoracic over-compression threshold.

Compressions achieved greater depths across both techniques using the CDmax56, with 44% of TT and 34% of TF chest compressions achieving the recommended targets. Compressions achieved depths that exceeded the proposed intra-thoracic injury threshold. The modified manikin (CDmax56) improved duty cycle compliance; however, the chest compression rate was consistently too high. Overall, the quality of chest compressions remained poor in comparison with internationally recommended guidelines.

This data indicates that the use of a modified manikin (CDmax56) as a training aid may encourage resuscitators to habitually perform deeper chest compressions, whilst avoiding thoracic over-compression and thereby improving current CPR quality. Future work will evaluate resuscitator performance within a more realistic, simulated CPR environment.

Introduction

Current European and UK Resuscitation Council's (ERC; UKRC) guidelines for infant cardiopulmonary resuscitation (CPR) emphasise that improved chest compression quality may improve survival rates.1, 2 The International Liaison Committee of Resuscitation (ILCOR), ERC and UKRC recommend the use of either the two-thumb (TT) or two-finger (TF) chest compression technique. Current chest compression recommendations include: compression depths of at least one-third the external anterior–posterior (AP) thoracic diameter (≈40 mm); compression rates of 100–120 min−1; complete release of the chest; 30–50% duty cycle (i.e. the proportion of each cycle with active chest compression).1, 2, 3, 4, 5, 6

The ERC and UKRC recommend that resuscitators push “hard and fast” to achieve the chest compression guidelines.1, 2 Whilst the maximum chest compression depth (CDmax) of industry-leading infant resuscitation manikins broadly correlate with the minimum clinical requirement (≈40 mm), manikin-based studies typically report that participants perform shallow chest compressions across a broad range of rates.7, 8, 9, 10, 11 The prevention of excessively deep chest compressions is also important as, for example, chest compression depths >46 mm have the potential to cause intra-thoracic injury in 90% of patients and thus hinder the possibility of full recovery.12, 13, 14, 15, 16, 17, 18

Previous studies have used manikins to investigate resuscitator performance7, 8, 9, 10, 11; however, with a CDmax limited to ≈40 mm, it is argued that this may have prevented resuscitators from achieving representative chest compressions.11, 19 This study develops a more “physiological” manikin design, thus enabling resuscitators to perform chest compression on a more representative model. The study will determine whether the new design encourages improved chest compression performance during training and greater compliance with the recommended guidelines, whilst also evaluating whether resuscitators inadvertently perform chest compressions to excessive depths.

Section snippets

Modified infant manikin design

A commercially available CPR training manikin (Laerdal® ALS Baby; Laerdal Medical, Stavanger, Norway), representing a three month old 5 kg male infant, was modified to allow CDmax to be varied between the original manikin specification (i.e. 40 mm; CDmax40), and the physiological internal chest depth of a three month old male infant (i.e. 56 mm; CDmax56).12 Manikin chest deflections, during simulated CPR, were measured by an infra-red sensor (Sharp Corporation, Osaka, Japan), with the 50 Hz output

Results

Forty certified EPLS instructors (22 female) participated in this study: 16 were resuscitation officers; 12 were doctors; eight were registered nurses; two were operating department practitioners and two were paramedics. The simulated chest compression quality measures observed by this study are illustrated against internationally recommended targets in Fig. 1.

For both the TT and TF techniques, the more “physiological” manikin design was observed to increase chest compression depths and reduce

Discussion

This study is the first to utilise a more “physiological” infant manikin design during simulated CPR, with results demonstrating improved chest compression depth and compression duty cycle compliance for both infant chest compression techniques. Despite these improvements, chest compression quality remained poor for both chest compression techniques, with <8% of all chest compressions complying with all four quality targets and both TT and TF chest compression techniques observed to

Conclusions

This study is the first to develop a more “physiological” manikin design that enabled resuscitators to perform chest compressions to greater depths. This manikin design improved the compliance of both chest compression depths and compression duty cycles with internationally recommended targets, whilst introducing the potential risks of thoracic over-compression during infant CPR. Despite this, overall chest compression compliance during simulated infant CPR remained very poor primarily due to

Conflict of interest statement

There are no competing financial interests, organisational ties or other relationships which may create an actual or apparent conflict of interest in regard to our study.

Acknowledgments

The authors would like to thank Dr. Ian Maconochie for his valuable comments in our preparation of this manuscript, and the staff and technicians at the Cardiff University Schools of Engineering and Medicine for their assistance throughout the performance of our investigation. The authors would also like to thank the EPLS training course organisers and NHS Trusts for hosting and helping organise this research, and the EPLS training course instructors that consented to participate in this study.

References (29)

Cited by (24)

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    The equipment used to analyse iCPR performance included: (i) a baby manikin representing a 5 kg, three-month-old infant (Laerdal® ALS Baby, Laerdal Medical, Stavanger, Norway). This manikin was modified during a previous study to allow a maximum compression depth of 56 mm30 and was instrumented with (ii) two accelerometers (one fixed on the manikin’s chest and the other on the board where the manikin was placed, acting as a differential, for the surface on which the CPR was conducted). Data were acquired by (iii) a data acquisition unit (LabView), connected to a (iv) personal computer (PC) and (v) a power supply.

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    For the critical outcomes of time to ROSC, survival rates, or neurologic injury, we found no data. For the critical outcome of improved perfusion and gas exchange during CPR, we identified low-quality evidence from 9 randomized controlled trials (downgraded for indirectness and imprecision)182–190 and 6 nonrandomized controlled trials (downgraded for indirectness, imprecision, and high risk of bias)191–196 identifying higher blood pressure generation with the 2-thumb versus the 2-finger method. For the important outcome of compressor fatigue, we identified low-quality evidence from 4 randomized controlled trials (downgraded for indirectness and imprecision), with 2183,197 identifying less fatigue with the 2-thumb versus the 2-finger technique, and 2 studies finding no difference.189,198

  • Real-time feedback can improve infant manikin cardiopulmonary resuscitation by up to 79%-A randomised controlled trial

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    This study utilised a commercially available CPR manikin (Laerdal® ALS Baby, Laerdal Medical, Stavanger, Norway), representing a three month old 5 kg male infant. The manikin had previously been modified to enable a more “physiological” maximum chest compression depth (i.e. an increase from 40 mm to 56 mm),15,16 whilst maintaining a chest compression stiffness consistent with that of the original design.15 The manikin was instrumented to measure chest deflections through analysing the output voltage of an infra-red distance measuring sensor (Sharp Corporation, Osaka, Japan).

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A Spanish translated version of the abstract of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2012.10.005.

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