What Lies Beneath: Why Some Pressure Injuries May Be Unpreventable for Individuals With Spinal Cord Injury.

OBJECTIVE: To investigate intersections between pressure injury (PrI) history, muscle composition, and tissue health responses under physiologically relevant loading conditions for individuals with spinal cord injury (SCI). DESIGN: Repeated measures study design with annual follow-up for up to 3 years. SETTING: Tertiary care center. PARTICIPANTS: Persons with SCI (N=38). Exclusion criteria included having an open pelvic region PrI at the time of recruitment, presence of systemic disease, and/or known sensitivity to contrast. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Gluteal muscle composition, ischial interface pressures, tissue oxygenation. RESULTS: Ischial region mean interface pressures are the same for individuals with or without a PrI history. Tissue oxygenation is lower during sitting for persons with a PrI history. Individuals with >15% gluteal intramuscular fat were statistically highly significantly (P<.001) more likely to have a history of severe or recurrent PrI. Intramuscular adipose tissue (IMAT) levels within the gluteal muscle may remain low over time or muscle tissue in the gluteal muscle region may be almost entirely replaced by IMAT. In the current study cohort, it was found that muscle composition also continues to change over time even for individuals with long-standing SCI. CONCLUSIONS: Soft-tissue compositional changes, specifically IMAT, provides a reliable indicator of PrI history and may provide a key to personalized PrI risk status for persons with SCI. The current findings confirm that interface pressure mapping alone is a limited indicator for PrI development.

Biomarkers for recurrent pressure injury risk in persons with spinal cord injury.

Objective: To investigate potential linkages between pressure injury (PrI) recurrence following spinal cord injury (SCI) and muscle-based and circulatory biomarkers, specifically fatty metabolites and inflammatory cytokines. Design: Observational study. Setting: Tertiary Care Center. Participants: 30 individuals with complete or incomplete SCI. Study participants either had never developed a PrI (Group I) or had a history of recurrent PrI (Group II). Interventions: Not applicable. Outcome Measures: Gluteal muscle histology, immunohistochemistry, muscle-based and circulatory fatty metabolites and inflammatory cytokines. Results: Gluteal intramuscular adipose tissue (IMAT) was greater than 15% in most Group II (83%) individuals. Muscle tissue histology confirmed intramuscular structural differences. Fatty acid binding protein 4 (FABP4) and fatty acid binding protein 3 (FABP3) were reliably detected in muscle and blood and significantly correlated with IMAT (P < 0.001). FABP4 was significantly higher in Group II muscle and blood (P < 0.05). FABP3 was significantly higher in Group I muscle (P < 0.05). Circulatory FABP3 levels were lower for Group I. Inflammatory biomarkers were more reliably detected in blood. Colony-Stimulating Factor-1 was slightly higher in Group II muscle. Circulatory interleukin-13 was significantly higher (P < 0.01) in Group I. Vascular endothelial growth factor (VEGF-A) was significantly increased (P < 0.05) in Group I muscle and blood. Conclusion: Identifying individuals with SCI at highest risk for recurrent PrI may impact patient management. IMAT content evaluation illustrates that muscle quality is a key biomarker. Low circulatory inflammatory biomarker expression potentially limits clinical significance for between group differences. Circulatory levels of FABP4 hold great potential as a recurrent PrI risk biomarker.

Real-time dual-modal vein imaging system.

PURPOSE: In this paper, we present a vein imaging system to combine reflectance mode visible spectrum images (VIS) with transmission mode near-infrared (NIR) images in real time. Clear vessel localization is achieved in this manner with combined NIR-VIS dual-modal imaging. METHODS: Transmission and reflectance mode optical instrumentation is used to combine VIS and NIR images. Two methods of displaying the combined images are demonstrated here. We have conducted experiments to determine the system's resolution, alignment accuracy, and depth penetration. Vein counts were taken from the hands of test subjects using the system and compared with vein counts taken by visual analysis. RESULTS: Results indicate that the system can improve vein detection in the human hand while detecting veins of a diameter < 0.5 mm at any working distance and of a 0.25 mm diameter at an optimal working distance of about 30 cm. The system has also been demonstrated to clearly detect silicone vessels with artificial blood of diameter 2, 1, and 0.5 mm diameter under a tissue depth of 3 mm. In a study involving 25 human subjects, we have demonstrated that vein visibility was significantly increased using our system. CONCLUSIONS: The results indicate that the device is a high-resolution solution to near-surface venous imaging. This technology can be applied for IV placement, morphological analysis for disease state detection, and biometric analysis.