Characterizing reactive hyperemia via tissue reflectance spectroscopy in response to an ischemic load across gender,age, skin pigmentation and diabetes

Purpose: Pressure ulcers represent a major secondary complication for amputees with diabetes and further complications may arise since ulcers are particularly hard to heal in this population. This study characterized the hyperemic response to a localized ischemic load in people with diabetes and amputation and compared it to that of subjects without diabetes or amputation. Subjects: Case-control study matching subjects by gender, age, skin pigmentation, and smoking status. Methods: Applying 150 mmHg to the patellar tendon for 10 minutes induced reactive hyperemia (RH). Tissue reflectance spectroscopy measured hemoglobin (HbO₂) concentration in tissue before, during and after application of pressure. Refill time, Maximum HbO₂, Time@Max HbO₂, RH area and RH half-life characterized the RH response and were analyzed using ANOVA. All values up to a level of p <0.1 are presented. Results: Analysis included responses from 88 subjects. RH magnitude and temporal parameters varied across skin pigmentation; smokers showed a decreased RH magnitude; vasodilator users had greater RH temporal parameters; no evidence of differences were found across disease state or age. Conclusion: Decreased RH response in smokers and subjects with dark skin might indicate a reduced ability to recover from ischemia. The lack of difference in RH response between subjects with and without diabetes was consistent with studies using other disability groups and corroborates the theory that RH is locally mediated.