Safety performance testing of climbing helmet-mounted cameras.

BACKGROUND: No research establishing the effects of climbing helmet-mounted cameras on head injury biomechanics. OBJECTIVE: Establish the potential effects of climbing helmet-mounted cameras on the injury risks associated with falling object strikes and falls onto flat and angled surfaces. METHODS: Three experimental studies were developed via the adaptation of European helmet testing standards and regulations. Study 1 performed falling striker tests to the helmet, Study 2 performed linear headform drop tests onto a flat anvil and Study 3 performed oblique headform drop tests onto an anvil angled 15° from vertical. Three helmet categories (hard-shell, foam and hybrid) were impacted at three locations (vertex, front and side), using five camera mounting combinations and three control helmets. Data was collected for the forces, linear accelerations, rotational velocities and rotational accelerations experienced by the headform. RESULTS: All helmet and camera combinations investigated by this project complied with current legislative performance criteria, while no combination exceeded published injury thresholds. No increase in head injury risk was observed for the forces transferred to the head during falling object strikes or with the linear accelerations experienced during falls onto flat and angled surfaces. Finally, although greater rotational head velocities and accelerations were observed with falls onto flat and angled surfaces, no injury threshold was exceeded by any investigated helmet and camera combination. CONCLUSIONS: All helmet and camera combinations investigated by this project complied with current legislative performance criteria, while no combination exceeded published injury thresholds. Further research may be required to establish the effects of additional impact mechanism, helmet or camera mounting configurations.

Development of a computational biomechanical infant model for the investigation of infant head injury by shaking.

The inertial loading thresholds for infant head injury are of profound medico-legal and safety-engineering significance. Injurious experimentation with infants is impossible, and physical and computational biomechanical modelling has been frustrated by a paucity of paediatric biomechanical data. This study describes the development of a computational infant model (MD Adams®) by combining radiological, kinematic, mechanical modelling and literature-based data. Previous studies have suggested the neck as critical in determining inertial head loading. The biomechanical effects of varying neck stiffness parameters during simulated shakes were investigated, measuring peak translational and rotational accelerations and rotational velocities at the vertex. A neck quasi-static stiffness of 0.6 Nm/deg and lowest rate-dependent stiffness predisposed the model infant head to the highest accelerations. Plotted against scaled infant injury tolerance curves, simulations produced head accelerations commensurate with those produced during simulated physical model shaking reported in the literature. The model provides a computational platform for the exploitation of improvements in head biofidelity for investigating a wider range of injurious scenarios.

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

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.