Use of near infrared spectroscopy to detect impaired tissue oxygen saturation in patients with complex regional pain syndrome type 1

Purpose

Deep tissue hypoxia has been hypothesized in the pathogenesis of complex regional pain syndrome type 1 (CRPS 1) for some patients. The purpose of this study was to determine if near-infrared spectroscopy (NIRS) could detect differences in deep tissue oxygen saturation (StO₂) and microcirculatory function in the hands of patients with CRPS 1.

Methods

Tissue oxygen saturation was evaluated at baseline and during an ischemia reperfusion challenge using vascular occlusion testing (VOT) in affected vs unaffected hands of patients with unilateral upper limb CRPS 1. A non-randomized experimental study design was used with baseline StO₂ as the primary outcome measure. Secondary outcome measures were occlusion and reperfusion slopes from VOT. Values were compared with the unaffected, contralateral hand and with the dominant and non-dominant hands of sex and age-matched volunteers. Correlations between values derived from NIRS and measures of pain and function from the Brief Pain Inventory (BPI) and the Disability of the Arm, Shoulder and Hand (DASH) questionnaires were explored.

Results

Independent of handedness, the baseline StO₂ of the affected hands of ten CRPS 1 patients was significantly lower than that of their unaffected hands (?5.8%; 95% confidence interval [CI] ?10.6 to ?1.0; P = 0.02). The baseline StO₂ of affected CRPS 1 hands was also significantly lower than the non-dominant hands of ten volunteers (?7.3%; 95% CI ?12.4 to ?2.3; P = 0.007). Differences in VOT occlusion and reperfusion slopes did not reveal changes that could be uniquely attributed to CRPS 1. No significant correlations were detected between values derived from VOT and values for pain and function obtained from BPI and DASH questionnaires for patients with CRPS 1.

Conclusions

Hands of patients affected by CRPS 1 of the upper limb showed significantly lower StO₂ compared with their unaffected contralateral hand as well as the hands of control subjects. This trial was registered at: ClinicalTrials.gov: NCT01586377.     

Near IR-plasmon enhanced guided fluorescence and thermal imaging of tissue subsurface target using ICG-labeled gold nanourchin and protein contrast agent: implication of stability

Lasers in Medical Science - A dual-function nanocomposite agent (NCA) was prepared for deep tissue fluorescence and thermal imaging. The results showed that a combination of some agents such as...     

Effect of dietary manipulations (fasting, hypocaloric feeding, and subsequent refeeding) on rat muscle energetics as assessed by nuclear magnetic resonance spectroscopy.

31P nuclear magnetic resonance (NMR) spectroscopy in vivo and fluorometry were used to measure muscle ATP, total creatine, pH, and Mg2+ in vivo; and to calculate creatine phosphate (CrP), the ratios of CrP/inorganic phosphate (Pi), CrP/ATP, free ADP levels, and the free-energy change in ATP hydrolysis so nutritional effects could be ascertained. These parameters were determined in vivo in resting control, 2-d-fasted, and hypocalorically fed rats and in animals similarly hypocalorically fed and then refed. The ATP, Pi, and intracellular Mg2+ levels were comparable in the four groups. When the fasted and underfed animals were compared with the control and refed animals, there were falls in the ratios of CrP/Pi and CrP/ATP, in the calculated CrP, and the free-energy change of ATP hydrolysis, but a rise in the calculated free ADP. In the hypocaloric group, intracellular pH fell significantly and a large peak was noted in the phosphodiester region. The data are consistent with the hypothesis that ATP levels are maintained at the cost of CrP, suggesting that ATP production is disturbed by aerobic and anaerobic mechanisms.     

Usability testing of multimodal feedback interface and simulated collision-avoidance power wheelchair for long-term-care home residents with cognitive impairments

Many older adults in long-term-care homes have complex physical and cognitive impairments and have difficulty propelling manual wheelchairs. Power wheelchair use is restricted owing to safety concerns. Power wheelchairs with collision-avoidance features are being developed to enable safe and independent mobility; however, a paucity of information exists on interface features to help users navigate away from obstacles. We developed a system combining an interface with auditory, visual, and haptic feedback and a simulated collision-avoidance power wheelchair. This device allowed the investigator to stop movement of the power wheelchair when users approached obstacles and to deliver feedback to help them navigate. Five long-term-care home residents with mild or moderate cognitive impairments evaluated device usability, which included effectiveness, efficiency, and user satisfaction. Each resident used the device for six 1 h sessions. Observations, feedback interviews, and outcome questionnaires were completed during and after the sessions. We found the device effective in enabling residents to achieve basic driving tasks and self-identified indoor mobility goals. Furthermore, residents perceived workload to be low and were satisfied with the device. Residents also felt that the feedback was useful to help them navigate away from obstacles.