Oxygenation Responses to Pressure Relief Techniques in People with Spinal Cord Injuries



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Purpose: This study measured the oxygenation responses of ischial skin during loaded and unloaded sitting in spinal cord injured subjects that use a manual wheelchair. Methods 10 subjects completed the pressure relief data collection, 9 males and 1 female, 37.1±10 years of age, and 7.1± 8.25 years post injury. The levels of injury were: 1 (C5- C6), 8 (T3-T9), and 1 (L1). A low-profile optic probe with a spectrophotometer allowed for real-time measurement of tissue oxygenation over the ischial tuberosity. Data was collected as the subject performed their usual sitting pressure relief program without cueing from the research team. After 1-hour (following a 30-minute lying in prone break to allow for revascularization of the ischial tuberosity) the subjects were cued to perform a push up pressure reliefs every 15 minutes and to hold for 2 minutes. The number, duration, and technique and direction of movements performed during the one-hour of wheelchair seated pressure relief data collection. Results: During the usual pressure relief x data collection, subjects performed 22.5 ± 19.8 (range 4-72) self-initiated pressure reliefs in one hour. 9 of the 10 subjects demonstrated a higher tissue oxygenation during the scheduled PR hour (p=<.001). Conclusion: There is large variability in the duration, frequency, and technique of pressure reliefs performed by spinal cord injured manual wheelchair users. Current practice for measuring pressure reliefs through interface pressure may not be providing the information needed to reduce the high occurrence of pressure injury in the manual wheelchair population. Tissue oxygenation is a more direct measurement of internal pressure. Understanding the relationship of tissue oxygenation during loaded and unloaded sitting conditions may lead to optimal seating assessments and pressure relief maneuvers in the prevention of pressure injuries.