The effect of pressure duration on sacral skin blood flow and sacral skin temperature in healthy adults and patients with either spinal cord injury or orthopedic trauma

Heat accumulation and interface pressure between a bony prominence and the hospital mattress during bedrest may be related to pressure ulcer (PU) development. The purpose of this study was to examine the effect of pressure duration on SSBF and TS in acute SCI subjects (n = 20) within 24-96 hours after injury, compared to acute orthopedic trauma (n = 35) and healthy (n = 47) Thai subjects. SSBF (Laser Doppler sensor) and TS (thermocouple sensor) were measured continually in the lateral position (baseline, pressure off) for 30 min, supine position (pressure on) for 120 min, and lateral position (recovery, pressure off) for 90 min. Baseline TS was higher ( p < .0001) in SCI compared to trauma and healthy subjects. During pressure loading, relative change in SSBF from baseline to 120 minutes interface pressure in SCI subjects was significantly decreased compared to trauma and healthy (p = .0004) subjects. At the same time course, SCI subjects had a smaller increase (p < .0001) in T S from baseline compared to trauma and healthy subjects. During recovery, time to the initial reactive hyperemia (RH) response for SSBF and TS in SCI subjects was shorter compared to trauma (p <.05) and healthy (p <.05) subjects. The initial slope of the RH response for SSBF was higher in SCI than trauma (p = .005) and healthy (p = .004) subjects. These findings suggest that SCI subjects had diminished vascular tone and impaired thermoregulation before and during exposure to interface pressure and impaired vascular reactivity after pressure release.