Using Skin Bioengineering to Highlight How Weight and Diabetes Mellitus Modify the Skin in the Lower Limbs of Super-Obese Patients

Proximal peroneal perforator flap, cadaveric study, and clinical applications for shallow defect reconstructions

PURPOSE

Peroneal artery perforator offers a versatile range of microvascular tissue transfer methods from local flaps to vascularized osteocutaneous fibula flaps. It is one of the few flaps that can cover shallow defects that require thin and pliable skin paddles, such as in hands and feet (Han et al., 2018). The proximal region of the lower leg offers such flexible and thin flap compared to the middle and distal lower leg (Winters & de Jongh, 1999). However, the anatomy of the proximal peroneal artery perforator is relatively unknown in literature and its proximity to the common peroneal nerve (CPN) has not yet been studied. This study conducted a cadaveric study and put it in application into clinical settings.

METHODS

Twenty lower leg specimens were dissected according to the methods of clinical proximal peroneal artery perforator flap harvest. Perforators arising in the proximal lower leg area of between 20 and 40 percentile of fibular length were inspected. Perforator length, location from fibular head, course, and location of CPN were recorded. Clinical reconstruction cases using the proximal lateral lower leg were analyzed. Six patients between the ages of thirty and seventy were included. Five cases were due to trauma, and one from mass excision, but all required thin and pliable flaps for reconstructions in hands or feet. Flaps were designed concentrical oval shapes, and harvest was done similarly to cadaveric perforator dissection, but perforator dissection was done only up to the required pedicle length. Perforator length, flap size, thickness, and long-term complications were recorded.

RESULTS

Among 20 specimens, a total of 20 perforators were found in 18 cadavers (90%). Two specimens showed no perforators while two specimens showed multiple perforators. The perforators were located at an average of 101 mm from fibular head, with an average length of 55 mm ranging from 20 to 153 mm. The average size of perforator at origin was 2.0 mm, ranging from 1.0 to 3.6 mm. 45% showed septocutaneous course and 55% intramuscular course. Two out of 20 perforators were shown to arise from source vessels other than the peroneal artery. All clinical cases were successful without complications or debulking for contour shaping. Flap sizes ranged from 15 to 40 cm² . Largest flap width was 5 cm, and all donor sites were primarily closed without complications. One year of follow-up showed no complications.

CONCLUSION

Proximal peroneal artery perforator flap provides a reliable pedicle for a versatile tissue transfer. This study shows that the perforators of the proximal lateral lower leg often arise from vessels other than the peroneal artery, such as the anterior tibial artery or popliteal artery, as had been previously reported (Winters & de Jongh, 1999). Although the source vessel varies, perforator anatomy is at a safe distance from CPN. This variation of source vessels suggests a change in nomenclature to "proximal peroneal perforator flap." The clinical applications of this flap showed that it can be effectively used for reconstructions of shallow defects, such as in the hands and feet without secondary procedures for debulking.

Skin optical properties in the obese and their relation to body mass index: a review

SIGNIFICANCE

Obesity is a worldwide epidemic contributing directly to several cardiovascular risk factors including hypertension and type 2 diabetes. Wearable devices are becoming better at quantifying biomarkers relevant for the management of health and fitness. Unfortunately, both anecdotal evidence and recent studies indicate that some wearables have higher levels of error when utilized by populations with darker skin tones and high body mass index (BMI). There is an urgent need for a better evaluation of the limits of wearable health technologies when used by obese individuals.

AIMS

(1) To review the current know-how on changes due to obesity in the skin epidermis, dermis, and subcutis that could affect the skin optical properties; (2) for the green wavelength range, to evaluate the difference in absorption and scattering coefficients from the abdominal skin between individuals with and without elevated BMI. The changes include alterations in layer thickness and cell size, as well as significant differences in chromophores and scatterer content, e.g., water, hemoglobin, collagen, and lipids.

APPROACH

We have summarized literature pertaining to changes in skin and its components in obesity and report the results of our search using articles published between years 1971 and 2020. A linear model was used to demonstrate the absorption and reduced scattering coefficient of the abdominal skin of individuals with and without elevated BMI in the green wavelength range (530 to 550 nm) that is typically found in most wearables.

RESULTS

The general trends indicate a decrease in absorption for both dermis and subcutis and an increase in reduced scattering for both epidermis and dermis. At 544-nm wavelength, a typical wavelength used for photoplethysmography (PPG), the absorption coefficient's relative percentage difference between high and low BMI skin, was 49% in the subcutis, 19% in the dermis, and negligible in the epidermis, whereas the reduced scattering coefficient relative difference was 21%, 29%, and 165% respectively.

CONCLUSIONS

These findings suggest that there could be significant errors in the output of optical devices used for monitoring health and fitness if changes due to obesity are not accounted for in their design.

Sources of Inaccuracy in Photoplethysmography for Continuous Cardiovascular Monitoring

Photoplethysmography (PPG) is a low-cost, noninvasive optical technique that uses change in light transmission with changes in blood volume within tissue to provide information for cardiovascular health and fitness. As remote health and wearable medical devices become more prevalent, PPG devices are being developed as part of wearable systems to monitor parameters such as heart rate (HR) that do not require complex analysis of the PPG waveform. However, complex analyses of the PPG waveform yield valuable clinical information, such as: blood pressure, respiratory information, sympathetic nervous system activity, and heart rate variability. Systems aiming to derive such complex parameters do not always account for realistic sources of noise, as testing is performed within controlled parameter spaces. A wearable monitoring tool to be used beyond fitness and heart rate must account for noise sources originating from individual patient variations (e.g., skin tone, obesity, age, and gender), physiology (e.g., respiration, venous pulsation, body site of measurement, and body temperature), and external perturbations of the device itself (e.g., motion artifact, ambient light, and applied pressure to the skin). Here, we present a comprehensive review of the literature that aims to summarize these noise sources for future PPG device development for use in health monitoring.

Ultrasound in the Modern Management of the Diabetic Foot Syndrome: A Multipurpose Versatile Toolkit

Ultrasound (US) is a noninvasive and versatile technology that in recent years found acceptance in almost all the medical specialties, with diagnostic and interventional applications. In the diabetic foot syndrome (DFS), US found specific indications mainly in the screening, quantification, and follow-up of the vascular component of the pathology, but also in the study of the deformities and structural modifications induced by neuropathy and in the diagnosis and surgical management of infections, especially those that induce anatomical changes, like abscesses and fasciitis. This review will summarize all these application of US, giving special attention to the vascular aspects, and on the predominant role that US gained in recent times to guide the indication to revascularization, on the new standardized approach to the study of the arterial tree of the limb and the foot, the so-called duplex ultrasound arterial mapping, which significantly increased the utilization of US to plan the revascularizations in this complex pathology. Outside the vascular fields, the diagnosis of neuropathy and infection and the intraoperative use of US in the surgical management of abscesses and fasciitis will be discussed, leaving the last part to the new and interesting applications of US in the management of DFU, a field that is still in evolution, offering new possibilities to the health care professionals involved in the management of these chronic wounds. The variety of applications both in diagnostic and operative fields makes US a rather versatile technology-a toolkit-that should have a special place among those at reach of the specialists of DFS care.