ARMY AEROMEDICAL RESEARCH LAB FORT RUCKER AL FORT RUCKER United States
The present report describes research assessing the effects mild hypoxia has on individuals with a medical history of mild traumatic brain injury mTBI. The research tests the hypothesis that individuals who have a history of mTBI but who are asymptomatic may have latent deficits that become apparent in the presence of relatively minor physiological stressors routinely encountered by military personnel or by civilians during normal daily activities. The research used a minor, altitude-referenced hypoxic challenge as a prototypical physiological stressor. The present report describes the methodology used to generate the hypoxic challenge as well as the experimental design and procedures. Two groups of 36 subjects were studied one group with a history of mTBI and one group with no such history. The report describes the characteristics of the study volunteers who were matched on the basis of such variables as age, gender, body mass index, and smoking behavior. The response parameters included oculometric, pulse rate, pulse oximetry, a self-report inventory of subjective symptoms, and neurocognitive assessments. The present report provides an extensive tabulation of the oculometric, pulse rate, pulse oximetry and inventory of subjective symptoms data as well as statistical summaries of these data and initial analyses. These initial analyses suggest that the oculometric instrumentation used in this study was insufficiently sensitive to expected differences whereas the pulse rate, pulse oximetry, and symptom severity data warrant further detailed analysis. A separate report addresses the neurocognitive assessments.