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Strength and Skin Temperature Assessment: Comparing Active and Geriatric Populations

Publication . Ricardo Vardasca, PhD, ASIS, FRPS

The age-related consequence of loss of skeletal muscle strength can be evaluated by handgrip force (HGF) tests. The assessment of this parameter is performed with dynamometers and it is frequently used as a functional indicator of different pathologies. During gripping exercises, physiological alterations occur that can be quantified with infrared thermography (IRT), adding information to an individual’s health status assessment. This work focus on the use of HGF and IRT measurements to evaluate differences among populations of active and institutionalized individuals, and on the identification of correlations between thermal parameters and HGF measurements. The study’s population included 30 active adults and 32 institutionalized individuals. Each performed an established handgrip exercise, mechanically stimulating forearm muscles. IRT images of this body region were recorded during the entire experiment. Three regions of interest (ROIs) were established for thermal image analysis, encompassing the digital flexor muscle region and the wrist ulnar and radial artery zone. Differences between populations were verified for the collected data, showing higher HGF measurements (Maximum force, Average force and Accumulated handgrip work) and elevated skin average temperatures for active adults, when compared to institutionalized participants. Strong correlations between HGF measurements and thermal parameters were also encountered, suggesting its relevance for future research. Thus, the results demonstrate the importance of pairing different types of technologies to increase the range of information and confidence in the results for possible medical applications. Some usages may include the diagnosis, prediction and treatment monitoring of musculoskeletal pathologies, as rheumatoid arthritis, tendinitis and carpal tunnel syndrome.

2019Journal article

Open access

Simulation of the hydrodynamic conditions of the eye to better reproduce the drug release from hydrogel contact lenses: experiments and modeling

Publication . Pimenta, A. F. R.; Valente, A.; Pereira, J. M. C.; Pereira, J. C. F.; Filipe, H. P.; Mata, J. L. G.; Colaço, R.; Saramago, B.; Serro, A. P.

Currently, most in vitro drug release studies for ophthalmic applications are carried out in static sink conditions. Although this procedure is simple and useful to make comparative studies, it does not describe adequately the drug release kinetics in the eye, considering the small tear volume and flow rates found in vivo. In this work, a microfluidic cell was designed and used to mimic the continuous, volumetric flow rate of tear fluid and its low volume. The suitable operation of the cell, in terms of uniformity and symmetry of flux, was proved using a numerical model based in the Navier-Stokes and continuity equations. The release profile of a model system (a hydroxyethyl methacrylate-based hydrogel (HEMA/PVP) for soft contact lenses (SCLs) loaded with diclofenac) obtained with the microfluidic cell was compared with that obtained in static conditions, showing that the kinetics of release in dynamic conditions is slower. The application of the numerical model demonstrated that the designed cell can be used to simulate the drug release in the whole range of the human eye tear film volume and allowed to estimate the drug concentration in the volume of liquid in direct contact with the hydrogel. The knowledge of this concentration, which is significantly different from that measured in the experimental tests during the first hours of release, is critical to predict the toxicity of the drug release system and its in vivo efficacy. In conclusion, the use of the microfluidic cell in conjunction with the numerical model shall be a valuable tool to design and optimize new therapeutic drug-loaded SCLs.

2016-12Journal article

Open access

Skin temperature of the foot: Reliability of infrared image analysis based in the angiosome concept

Publication . Ricardo Vardasca, PhD, ASIS, FRPS

Objective: Studies reporting the reliability of image analysis when assessing skin temperature of the foot are scarce. The aim of this study was to assess the interrater and intrarater reliability of the analysis of foot skin temperature based on the angiosome concept and the association between skin temperature differences and the differences in size of the ROIs. Methodology: Thermograms from 26 feet were analysed by two independent assessors and each assessor analysed the same images on different occasions. Mean temperature values of each of the six ROIs were extracted for analysis. Relative reliability was assessed by Intraclass Correlation Coefficient (ICC) measures and absolute reliability was assessed using Bland and Altman agreement measures and standard error of measurement (SEM). The Spearman correlation coefficient was used to assess the association between the skin temperature differences and the differences in size of the ROIs in the interrater and intrarater analysis Results: The ICC values evidenced excellent interrater and intrarater reliability with the 95% confidence intervals (CI) ranging between 0.962 and 1.000 and the SEM ranged between 0.00 °C and 0.36 °C. The mean absolute difference (bias) between the measurements ranged between 0.002 °C and 0.117 °C and small to moderate associations between the differences in skin temperature and the difference in the number of pixels were identified.Conclusion: The excellent interrater and intrarater reliability measures suggest that the methodology of analysis was reliable and may be used in research and clinical settings. Although statistical significant associations between the skin temperature differences and the differences in size of the ROIs were found, the magnitude of the skin temperature differences between assessments and between assessors (0.02–0.17 °C) is not clinically relevant.

2018Journal article

Open access