Application of a novel finger temperature device in the assessment of subjects with Raynaud's phenomenon

An Experimental Phototherapy Device for Studying the Effects of Blue Light on Patients with Raynaud's Phenomenon

Raynaud's phenomenon (RP) is a condition that causes decreased blood flow to areas perfused by small blood vessels (e.g., fingers, toes). In severe cases, ulceration, gangrene, and loss of fingers may occur. Most treatments focus on inducing vasorelaxation in affected areas by the way of pharmaceuticals. Recently, animal studies have shown that vasorelaxation can be induced by non-coherent blue light (wavelength ~ 430-460 nm) through the actions of melanopsin, a photoreceptive opsin protein encoded by the OPN4 gene. To study this effect in humans, a reliable phototherapy device (PTD) is needed. We outline the construction of a PTD to be used in studying blue light effects on Raynaud's patients. Our design addresses user safety, calibration, electromagnetic compatibility/interference (EMC/EMI), and techniques for measuring physiological responses (temperature sensors, laser Doppler flow sensors, infrared thermal imaging of the hands). We tested our device to ensure (1) safe operating conditions, (2) predictable, user-controlled irradiance output levels, (3) an ability for measuring physiological responses, and (4) features necessary to enable a double-blinded crossover study for a clinical trial. We also include in the Methods an approved research protocol utilizing our device that may serve as a starting point for clinical study. We introduced a reliable PTD for studying the effects of blue light therapy for patients suffering from Raynaud's phenomenon and showed that our device is safe and reliable and includes the required measurement vectors for tracking treatment effects throughout the duration of a clinical study.

Can peripheral biomarkers reflect the psychological condition in geriatric populations? The influence of cardiovascular comorbidities

BACKGROUND

Although previous studies indicated the association between peripheral biomarkers and psychological conditions, a higher prevalence of cardiovascular diseases (CVD) among geriatric populations may hinder the applicability of the biomarkers. The objective of this study was to assess the adequacy of the application of biomarkers to evaluate psychological conditions among geriatric populations.

METHOD

We collected information on the demographics and history of CVD in all participants. All participants completed the Brief Symptom Rating Scale (BSRS-5) and the Chinese Happiness Inventory (CHI), which are the measurement of negative and positive psychological conditions, respectively. Four indicators of the peripheral biomarkers, including the standard deviation of normal to normal RR intervals (SDNN), finger temperature, skin conductance, and electromyogram were collected for each participant during a 5-min resting state. Multiple linear regression models were conducted to evaluate the association between the biomarkers and the psychological measurements (BSRS-5, CHI) with and without the inclusion of the participants with CVD.

RESULTS

A total of 233 participants without CVD (non-CVD group) and 283 participants with CVD (CVD group) were included. The CVD group was older and with higher body mass index compared to the non-CVD group. In the multiple linear regression model with all participants, only BSRS-5 scores had a positive association with electromyogram. After the exclusion of the CVD group, the association between the BSRS-5 scores and electromyogram was more relevant, while CHI scores became positively associated with SDNN.

CONCLUSIONS

A single measurement of the peripheral biomarker may be insufficient to depict psychological conditions among geriatric populations.

Definition and application of proximal-distal gradient finger perfusion in systemic sclerosis by laser speckle contrast analysis

OBJECTIVE

In patients with systemic sclerosis (SSc) the perfusion of the fingers shows an alteration of the physiological proximal-distal gradient (PDG). The aim of this study is to provide a generalizable definition of PDG, applying it in a cohort of SSc patients and healthy controls (HC) using laser speckle contrast analysis (LASCA).

METHODS

Adult consecutive SSc patients and HC were enrolled. Peripheral blood perfusion of the hands was evaluated by LASCA, subsequently obtaining 3 different regions of interest: from the distal interphalangeal joint to the fingertip (DIST), from the metacarpophalangeal joint to the distal interphalangeal joint (PROX), and of the whole finger (TOT). A PDG formula independent of both intra- and inter-personal factors was then built. The PDG formula so obtained was: [(DIST × 2.63) - PROX]/TOT.

RESULTS

Ninety-four SSc patients (79.8% female, mean age 58.7 years) were enrolled. Applying the PDG formula, SSc patients revealed mean PDG values significantly lower than HC (1.82 ± 0.44 PU vs 2.70 ± 0.38 PU; p < 0.0001). Patients with a previous history of digital ulcers presented significant lower PDG values (p = 0.002). The ROC curve analysis identified in 2.28 PU the best PDG cut-off value between SSc and HC, with 86% sensibility and 90% specificity.

CONCLUSION

This study provided a PDG formula generalizable to all kind of subjects, applying it in SSc with great sensibility and specificity using LASCA, the best non-invasive imaging technique for the dynamical evaluation of peripheral perfusion. LASCA-PDG appears also as a tool able to identify a subclinical microangiopathic impairment.