Supine human response and vibration-suppression during whole-body vibration

Supine human response and vibration-suppression during whole-body vibration." MS (Master of Science) thesis, ii ACKNOWLEDGMENTS I would like to acknowledge the U.S. Army Aberdeen Test Center (ATC) for the use of the inertial sensors, the USA Army Research Lab (USAARL) for providing the litter, Dr. David Wilder for providing the long spinal board and cervical collar, Mr. Jonathan DeShaw for assisting in the experimentation, and the Johnson County Ambulance Service (JCAS) for the spinal immobilization demonstration. for their insights, feedback, and educational experiences. Finally, I would like to express my gratitude to my advisor Dr. Salam Rahmatalla for his encouragement, guidance, and expertise. His passion for research and academia has continually inspired me to reach higher bounds. iii ABSTRACT Whole-body vibration (WBV) has been identified as a stressor to supine patients with head and spinal injuries during medical transportation. Limited information is available on the dynamic effects of the long spinal board and stretcher in vibrating environments. This is the first study to investigate the transmission of vibration through the long spinal board, military stretcher, and supine human in relation to a control case with full-rigid support. A sample of eight healthy male participants was used in this study. Each was placed on a vibration platform using spinal immobilization. Random vibration was applied in the fore-aft, lateral, and vertical directions, and the transmission of vibration was computed for the head, sternum, and pelvis. In addition, a novel approach to assess relative motion between segments, called relative transmissibility, was introduced. Compared to full-rigid support, the long spinal board strapped to a standard military litter system showed a 50% increase in transmission of anterior-posterior vibration to the head and a 100% increase to the sternum at its resonance frequency of 5 Hz (p < 0.05, Wilcoxon) for vertical vibration. Use of the cervical collar during immobilization increased the head nodding and the relative head-sternum flexion-extension as a result of the input fore-aft (axial) whole-body vibration. Yet, head nodding was reduced from vertical (anterior-posterior) input vibration. Relative transmissibility has revealed that at 5 Hz, the acceleration difference between the head and sternum was 1.5 times the vertical (anterior-posterior) input acceleration using the spinal board upon the military litter. During air, ground, and hand transportation, WBV may occur around 5 Hz. Patients with head and spinal cord injuries may benefit from vibration-suppression designs that minimize (1) the overall transmission of vibration in iv each …