RELATIONSHIP BETWEEN BACKPACK WEAR AND BLOOD FLOW IN THE BRACHIAL ARTERY. Nancy Talbott*1; A Bhattacharya2; S O'Hara3; T Adams3 1. University of Cincinnati, Cincinnati, OH; 2. Department of Environmental Health, University of Cincinnati, Cincinnati, OH; 3. Children's Hospital Medical Center, Cincinnati, OH PURPOSE: The purpose of this study was to determine if brachial artery blood flow changes while wearing a backpack. BACKGROUNDS/SIGNIFICANCE: During backpack wear, significant pressure is placed on the superior and anterior scapular areas. While children often complaining about upper extremity pain and numbness and tingling, there is, little information about the potential reasons for these symptoms and the possible effects the compression from the backpack may have on upper extremity circulation. As physical therapists are often involved in the treatment of backpack related symptoms and education about backpack wear, an explanation of the etiology of the pain is important. SUBJECTS: Five students, four females and one male, grades 5-9, participated in the study. METHODS AND MATERIALS: Utilizing a Doppler Ultrasound, peak blood flow in the right brachial artery was measured under three conditions: without a backpack; while wearing a backpack high on the back (superior aspect of the backpack at C7) that weighed 20%of the bodyweight; and while wearing a backpack low on the back (superior aspect of the backpack at inferior angle of the backpack) that weighed 20% of the bodyweight. Order was randomized. On a second day of testing, testing was done without a backpack, with a backpack weighing 20% of the bodyweight and again eight minutes after the backpack was removed. ANALYSES: Descriptive analysis and repeated measure ANOVAs were completed to determine the association between average blood flow and backpack wear. RESULTS: Average peak flow without a backpack, on both days was 32.82 m/sec, significantly higher that the average peak flow of 28.62m/sec measured while wearing a backpack with 20% bodyweight (p<.001). Position also significantly affected the ultrasound velocity. When worn high on the back, peak values averaged 27.83 m/sec, significantly less (p<.05) than the baseline and the average peak value of 30.20m/sec that was found when the backpack was worn low on the back. Further ANOVA testing revealed that BMI, heart rate, age, day, and repetition were not significant in a model for velocity measurements but position and backpack weight were significant. In addition, time was not a significant factor but the trend was noted for several subjects to continue to have a decrease in the peak blood flow even after the backpack had been removed. CONCLUSIONS: While the cumulative effects of decreasing blood flow are speculative, further study into the effects of backpacks on blood flow including descriptions of the pattern of flow after removal of the backpack are warranted. Physical therapists should be aware than blood flow in the upper extremities may change with backpack wear. FUNDING SOURCE: Funding provided by the Department of Environmental Health, College of Medicine, University of Cincinnati. The authors have no potential for material gain from this study. KEYWORDS: backpacks, blood flow, brachial artery Copyright 2009 by the American Physical Therapy Association. Requests for reprints should be directed to the corresponding author of the article. Educators, students, and other academic customers may receive permission to reprint copyrighted material from Physical Therapy (ISSN 1538-6724) by contacting the Copyright Clearance Center Inc, 222 Rosewood Dr, Danvers, MA 01923. Other types of customers who want permission to reprint should contact the APTA Editorial Office, Attn: Physical Therapy.