Vibration and Shock Exposure Limits for Transport of the Acute Spinal Cord Injured

We are conducting research to develop guidelines for medical professionals to use when people with severe injuries such as spinal cord injury must be transported by ambulance, helicopters, or airplanes. These vehicles cause vibration, and right now it is not known if the transportation vibration can cause the injury to become worse. We do know that moving people with severe injuries like spinal cord or brain injuries can cause further injury, and our hypothesis in this research is that vibration associated with transportation can also cause further injury to someone with a serious injury such as a spinal cord injury. A guideline that defines the maximum type and time of vibration for spinal cord injured subjects would help to prevent patients with these injuries from suffering more injury during transportation. Because these injuries cannot be simulated in healthy humans, it is our goal to identify these criteria using a model that we have developed where anesthetized pigs with spinal cord injuries can be exposed to vibrations.

The 'worst case' vibrations will be identified by placing the pigs on a machine that can produce vibrations and then applying different speed vibrations. The motion of the pig's spines is measured with a special high speed x-ray machine that can collect thousands of x-rays every second and with sensors that can be attached to the spine to measure its motion.

The biological effects of various doses of vibration will be determined by measuring chemicals that are produced during injury in the fluid next to the spinal cord. We will also look at the damage to the cord itself under a microscope after the experiment. Also, for 6 weeks after the injury, the paralyzed pigs will exercise, and their ability to move their back legs will be studied as a measure of how much worse the injury was made by the vibration (if at all). There will be groups of animals exposed to 1.5 and 3 hours of vibration that represents transport by ambulance, helicopter, or at the 'worst case' vibration that we identified earlier. Soldiers often have to travel for these time periods if they are injured in battle.

This project is collaborative with the United States Army Aeromedical Research Laboratory (USAARL) and the University of Iowa (UI). At the University of British Columbia (UBC), we will use our pig subjects to determine the biological effect of various vibrations. This will complement the UI research where human subjects will be exposed to vibration typical of transport while their spine, head, neck, and arm and leg motion will be measured. Our partners at USAARL will measure the vibrations of several evacuation vehicles like helicopters, airplanes, and ambulances. These vibrations will be applied to the porcine subjects at UBC and to the human subjects at UI. These projects are complementary and synergistic in that the UI research cannot be ethically conducted with injured humans, but the measured motions will be most representative of human in the UI research. In contrast, in the porcine experiments, we can study the effect of the vibration on the injured spinal cord. However, without the UI research, we would not know if the porcine response to vibration is similar or can be related to the situation in humans.