An Evaluation of the Performance of Medical Helmets Used in Healthcare for Protection of Vulnerable Patients

Rory England ^1* Marina Haynes ¹ Harry Mee ² Jon Farmer ¹

• ¹ Loughborough University, Loughborough, United Kingdom
• ² University of Cambridge, Cambridge, England, United Kingdom

Introduction: Medical helmets are used by those with increased vulnerability to falling and are essentially unregulated in the UK -therefore their impact performance is unproven. This study investigated the performance of a selection of medical helmet's available to clinicians using general techniques to determine protective performance against impacts. Additionally, clinicians state that medical helmets need to consider focal vulnerabilities to impact (often a post-surgical site of a decompressive craniectomy) therefore novel techniques were specifically targeted at measuring the protection of a focal site. Materials and Methods: A freefall drop test methodology was used to test six medical helmets (MH1-6) and two sports helmets (SH1&2). The headform was instrumented with six degrees of freedom instrumentation to quantify metrics of global kinematics related to injury risk (peak linear acceleration, peak angular velocity, peak angular acceleration, head injury criterium and brain injury criterium) and a thin film contact pressure measurement system to quantify the contact area (above a threshold of 560 kPa) focal to the impact. Because the advanced nature of these measurements a novel biofidelic headform was used to more closely represent local deformation. Additionally, impact performance was plotted against two proxy measures of comfort. Results: The difference between the worst and best helmet was from 90% to 2844% larger showing a large range in performance. HIC, PLA and PAA showed the largest range, and PAV showed the smallest range. None the less there was good agreement between each kinematic metric on the rank order of the medical helmet's. Contact pressure was the consistent outlier. Each metric had at least one threshold for injury plotted, which MH4 and MH6 consistently exceeded (15/18 occasions). Discussion: MH2 and MH3 were the only medical helmets that were comparable to the sports helmets in both comfort and performance. MH1 showed good performance metrics but exhibited possible discomfort, while MH4 was average across both categories of measurement. MH4 and MH6 were significantly deficient in comparison to the sample of helmets. This range of results highlights the need for standardisation.