Elsevier

Resuscitation

Volume 74, Issue 1, July 2007, Pages 127-134
Resuscitation

Manikin and simulation study
Chest compressions by ambulance personnel on chests with variable stiffness: Abilities and attitudes

https://doi.org/10.1016/j.resuscitation.2006.12.006Get rights and content

Summary

Introduction

Quality of cardiopulmonary resuscitation (CPR) performed by professionals is reported to be substandard even with automated corrective feedback. We hypothesised that lack of quality is not due to physical capabilities.

Materials and methods

Eighty ambulance personnel from the same services where the quality of clinical CPR was investigated, performed two-rescuer CPR with similar corrective feedback for 5 min on each of four manikins with different chest stiffness. The personnel also scored their agreement with statements on clinical CPR performance.

Results

All study subjects performed CPR well within Guidelines recommendations on all four manikins with mean compression depth 44 ± 3 mm, compression rate 101 ± 3 min−1, and 7 ± 2 ventilations per minute. Three quarters stated that during CPR on patients their personal sense of correct depth and force determined their performance. Fifty-five percent believed that too deep chest compressions could cause serious injury to the patient, and 39% that compressing to Guidelines recommended depth may often result in severe patient injury. A quarter felt that the potential benefits of compressing to the Guidelines depth could not justify the injuries it would cause. Breaking ribs made 54% feel very uncomfortable.

Conclusions

Ambulance personnel were physically capable of consistently compressing to the Guidelines depth even on the stiffest chest. These laboratory results cannot be directly compared to the clinical out-of-hospital ALS situation, but strongly indicate that the inadequate chest compressions found in our clinical study were not due to lack of physical capability. We speculate that this may at least partly be explained by their fear of causing patient injury and trust in their own opinion of what is the correct compression depth and force in preference to the feedback.

Introduction

Recent studies have shown that quality of cardiopulmonary resuscitation (CPR) performed by professionals out-of-hospital is substandard with shallow chest compressions and almost half the time without chest compressions (no flow time).1, 2 In manikin studies automated feedback consistently improve CPR performance to be well within Guidelines recommendations for most rescuers,3, 4, 5, 6 and Kramer-Johansen et al. recently reported that similar feedback also improved quality during out-of-hospital CPR.7 However, even with feedback, mean chest compression depth was at the lower limit of Guidelines recommendations,8 38 mm, and no chest compressions were performed for nearly half the time.

We therefore wondered whether professional rescuers were physically capable of compressing to the Guidelines depth8 on patients. This has been questioned by Gruben et al. who reported that 38 mm was reached in only seven of 16 patients, and that the force required varied greatly between patients.9

We recruited personnel from the same ambulance services as were used in the clinical CPR quality studies1, 7 to perform chest compressions on manikins with different chest stiffness based on recent clinical findings in 91 patients.10 They received feedback as in the clinical study7 and in addition the personnel answered questions related to variables that might influence their performance and priorities in real out-of-hospital cardiac arrest.

Section snippets

Subject recruitment

Study subjects were 80 volunteers recruited in connection with ALS retraining sessions for ambulance personnel in Akershus, Norway and London, UK. Using the statistical software package SigmaStat (Systat Software Inc., Richmond, California, USA) we calculated that 27 subjects would be needed in a paired design to obtain a power of 0.85 to detect a change in mean compression depth of five mm from 38 ± 6 (S.D.)7 with alpha 0.05.

Manikin and data collection system

The manikins were four modified Skillmeter Resusci Anne manikins with

Demographic data

Median age range of the 80 study subjects was 30–40 years (<30, 30–40) and 71% were men. Median weight range was 71–80 kg (61–70, 81–90) and height range 176–185 cm (165–175, >185).

Compressions

Mean compression depth was 44 ± 3 mm. Mean chest compression depth was gradually, and significantly reduced with increasing chest stiffness (P < 0.005 for manikin 1 versus manikin 2, P = 0.01 for manikin 2 versus manikin 3 and P < 0.005 for manikin 3 versus manikin 4) (Figure 2), but for all four manikins the whole range of

Discussion

The present study documents that ambulance personnel were physically capable of compressing to the Guidelines depth8 for 5 min even on a manikin with chest stiffness mimicking the mean value of the upper eighth of the chest stiffnesses found in a recent clinical study from the same ambulance systems.10 Using defibrillators capable of accurately measuring chest compression depth, we have previously reported that ambulance personnel compressed the chest to only 34 ± 9 mm in a clinical study of 234 000

Conclusion

Ambulance personnel were physically capable of compressing to the Guidelines depth even on the stiffest manikin chests. We speculate that the clinical finding of too shallow chest compressions might partially be explained by the ambulance personnel being afraid of causing patient injury and trusting their own opinion of what is the correct compression depth and force more than automated feedback.

Conflict of interest statement

Authors Ødegaard and Bromley have no conflict of interests to declare. Kramer-Johansen, Wik, and Steen have received research support from Laerdal Medical for previous studies of CPR quality. Myklebust and Nysæther are full time employees on fixed salary at Lærdal Medical, Stavanger. Wik is on an advisory board for Medtronic Medical. Steen is member of the Board of Directors for Laerdal Medical.

Acknowledgements

We would like to thank all participating ambulance personnel who contributed to this study by their enthusiasm and effort. We also thank the section leaders at the different ambulance services; Karianne Aune, Torstein Johnsen, Sverre Aae in Akershus and clinical tutors in London. The helpfulness and technical skills of Geir Inge Tellnes was invaluable, and also great thanks to Mitch Loeb at SINTEF, Oslo for statistical guidance and help, and to Bob Fellows for support and help in the planning

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