Effect of thoracic stiffness on chest compression performance - A prospective randomized crossover observational manikin study

INTRODUCTION: Human thoracic stiffness varies and may affect the performance during external chest compression (ECC). The Extra Compression Spring Resusci® QCPR Anne manikin is a high-fidelity training model developed for ECC training that can account for varying levels of thoracic stiffness. The aim of this study was to use this training model to investigate the effects of thoracic stiffness on ECC biomechanics and qualities. METHODS: Fifty-two participants performed standard ECC on the manikin with different thoracic springs to simulate varying levels of thoracic stiffness. The MatScan Pressure Measurement system was used to investigate the ECC pressure and force distribution. RESULTS: The hard spring group’s performance had a better complete recoil ratio (90.06 ± 24.84% vs. 79.75 ± 32.17% vs. 56.42 ± 40.15%, p < 0.001 at second minute), but was more inferior than the standard and soft spring groups in overall quality, ECC depth (34.17 ± 11.45 mm vs. 41.25 ± 11.42 mm vs. 51.88 ± 7.56, p < 0.001 at second minutes), corrected depth ratio, and corrected rate ratio. The hard spring group had less radial-ulnar peak pressure difference (kgf/cm(2)) than the other two groups (−0.28 ± 0.38 vs. −0.30 ± 0.43 vs. −0.47 ± 0.34, p = 0.01), demonstrating that more symmetrical pressure was applied in the hard spring group. The soft spring group had better ECC depth, corrected depth ratio, corrected rate ratio, and overall quality, but its performance in complete recoil was inferior, and unbalanced pressure was more liable to cause injury. Hard springs caused operator fatigue easily. CONCLUSION: The thoracic stiffness greatly affected the performance of ECC. Our findings provided information for more effective ECC practices and training.