Near-Infrared Spectroscopy Measurement of Sacral Tissue Oxygen Saturation in Healthy Volunteers Immobilized on Rigid Spine Boards

Abstract

Introduction. Immobilization of patients utilizing rigid spine boards (RSBs) is standard practice in the management of trauma patients. Pressure ulcers have been associated with prolonged immobilization, and the possibility exists that formation may begin when the patient is initially immobilized on the RSB. The effects may not be fully recognized because of limited research on the direct tissue effects of prolonged immobilization. Near-infrared spectroscopy is an emerging tool to measure peripheral tissue oxygen saturation (StO₂). The purpose of this research was to study the effects of prolonged spinal immobilization on an RSB on sacral tissue oxygenation of healthy volunteers. Methods. This experimental study measured StO₂ in healthy volunteers at baseline and again after 30 minutes of immobilization on an RSB at two sites: the sacral area (intervention) and 8–10 cm above the buttocks (control). Tissue oxygenation was measured with the InSpectra Tissue Oxygenation Monitor (Hutchinson Technology, Hutchinson, MN) by placing the probe at the measurement site and waiting for 15 seconds for equilibration prior to recording StO₂. Data were analyzed utilizing mixed-model and within-subjects analysis of variance (ANOVA), chi-square, and t-tests. Results. Seventy-three participants were included in the analysis. A slight majority of participants were female (55%), the average age was 38 years, the average height was 170 cm, and the average weight was 82 kg. There was a significant increase in the StO₂ percentage at the sacral (intervention) area following immobilization, p < 0.001, point biserial correlation (r_pb) = 0.48. Significant changes in oxygenation were not noted at the control site. Conclusion. An increase in sacral tissue oxygenation following immobilization was a finding consistent with other research. This is likely a result of initial, rapid tissue reperfusion at the time of pressure release. Rapid reperfusion indicates that a period of previous hypoperfusion has occurred. This research indicates that there are detrimental effects of spine board immobilization in healthy volunteers, which suggests that pressure ulcer formation may begin prior to hospital admission with immobilization on an RSB.

Key words :

• pressure ulcer
• tissue necrosis
• near-infrared spectroscopy
• immobilization
• spine boards