Serum levels of biomarkers related to severity staging of Raynaud's phenomenon, neurosensory manifestations, and vibration exposure in patients with hand-arm vibration injury.

Our aim was to explore possible relationships between serum levels of biomarkers in patients with hand-arm vibration injury in relation to the severity of the vascular, i.e., Raynaud's phenomenon (RP), and neurosensory manifestations, the current exposure level, and the duration of exposure. This study was of case series design and involved 92 patients diagnosed with hand-arm vibration injury. Jonckheere's trend test was used to assess any association between serum levels of biomarkers and RP as well as neurosensory manifestations, graded by the International Consensus Criteria. Generalized linear models with adjustment for possible confounders were also used for associations between serum levels of biomarkers and; (1) severity of RP recorded as the extent of finger blanching calculated with Griffin score, (2) vibration perception thresholds, (3) magnitude of current exposure as [A(8); (m/s2)] value, and (4) the duration of exposure in years. Serum levels of thrombomodulin, von Willebrand factor, calcitonin gene related peptide (CGRP), heat shock protein 27, and caspase-3 were positively associated with severity of RP. Serum levels of CGRP were positively associated with the neurosensory component. No associations with exposure were shown for these biomarkers. For Intercellular adhesion molecule 1 and monocyte chemoattractant protein 1, no associations were found with neither severity nor exposure. Levels of serum biomarkers associated with endothelial injury or dysfunction, inflammation, vasodilation, neuroprotection, and apoptosis were positively associated with the severity of hand-arm vibration injury.

Portuguese Recommendations for the management of Raynaud's phenomenon and digital ulcers in systemic sclerosis and other connective tissue diseases.

OBJECTIVE: To develop evidence-based recommendations for the non-pharmacological and pharmacological management of Raynaud's phenomenon (RP) and digital ulcers (DUs) in patients with systemic sclerosis and other immune-mediated connective tissue diseases (CTDs). METHODS: A task force comprising 21 rheumatologists, two surgeons (vascular and plastic), two nurses, and one patient representative was established. Following a systematic literature review performed to inform the recommendations, statements were formulated and discussed during two meetings (one online and one in-person). Levels of evidence, grades of recommendation (GoR), and level of agreement (LoA) were determined. RESULTS: Five overarching principles and 13 recommendations were developed. GoR ranged from A to D. The mean ± standard difference (SD) LoA with the overarching principles and recommendations ranged from 7.8±2.1 to 9.8±0.4. Briefly, the management of RP and DUs in patients with CTDs should be coordinated by a multidisciplinary team and based on shared decisions with patients. Nifedipine should be used as first-line therapy for RP and/or DUs. Sildenafil, tadalafil, and/or iloprost IV are second-line options for severe and/or refractory patients with RP and/or DUs. Sildenafil, tadalafil and/or Iloprost IV, should be prescribed for healing and prevention (also including bosentan) of DUs. In patients with RP and/or DUs, non-pharmacological interventions might be considered as add-ons, but there is limited quality and quantity of scientific evidence supporting their use. CONCLUSIONS: These recommendations will inform rheumatologists, specialist nurses, other healthcare professionals, and patients about a comprehensive and personalized management of RP and DUs. A research agenda was developed to address unmet needs, particularly for non-pharmacologic interventions.

Raynaud's Phenomenon of the Nipple: Epidemiological, Clinical, Pathophysiological, and Therapeutic Characterization.

Raynaud's phenomenon of the nipple is a possible cause of pain and breastfeeding cessation in lactating women. However, there are still few studies on the characterization of this manifestation. Thus, we aim to develop a systematic review of the literature carried out between January 1992 and January 2024 in PubMed, Scopus, Web of Science, Virtual Health Library (VHL), and Portal de Periódicos da CAPES. Of the 438 articles, 19 met the eligibility criteria. The findings were divided by heuristic questions into two groups: "Epidemiological, pathophysiological, and clinical characterization of Raynaud's Phenomenon of the nipple" and "Treatment of Raynaud's Phenomenon of the nipple". Raynaud's phenomenon of the nipple is commonly primary, being more prevalent in the postpartum period, in women with a mean age of 32 years. The main triggers appear to be stress and temperature change. Generally, it is associated with a change in color and pain during breastfeeding. A calcium channel blocker was the most used medication with or without non-pharmacological measures.

2023 Brazilian Society of Rheumatology guidelines for the treatment of systemic sclerosis.

BACKGROUND: Systemic sclerosis (SSc) is a rare chronic autoimmune disease with heterogeneous manifestations. In the last decade, several clinical trials have been conducted to evaluate new treatment options for SSc. The purpose of this work is to update the recommendations of the Brazilian Society of Rheumatology in light of the new evidence available for the pharmacological management of SSc. METHODS: A systematic review including randomized clinical trials (RCTs) for predefined questions that were elaborated according to the Patient/Population, Intervention, Comparison, and Outcomes (PICO) strategy was conducted. The rating of the available evidence was performed according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. To become a recommendation, at least 75% agreement of the voting panel was needed. RESULTS: Six recommendations were elaborated regarding the pharmacological treatment of Raynaud's phenomenon, the treatment (healing) and prevention of digital ulcers, skin involvement, interstitial lung disease (ILD) and gastrointestinal involvement in SSc patients based on results available from RCTs. New drugs, such as rituximab, were included as therapeutic options for skin involvement, and rituximab, tocilizumab and nintedanib were included as therapeutic options for ILD. Recommendations for the pharmacological treatment of scleroderma renal crisis and musculoskeletal involvement were elaborated based on the expert opinion of the voting panel, as no placebo-controlled RCTs were found. CONCLUSION: These guidelines updated and incorporated new treatment options for the management of SSc based on evidence from the literature and expert opinion regarding SSc, providing support for decision-making in clinical practice.

Blood biomarkers for occupational hand-arm vibration exposure.

Hand-arm vibration is a common occupational exposure that causes neurological impairment, myalgia, and vibration-induced Raynaud's phenomena or vibration white fingers (VWF). The pathological mechanism is largely unknown, though several mechanisms have been proposed, involving both immunological vascular damage and defective neural responses. The aim of this study was to test whether the substances interleukin-33 (IL-33), macrophage-derived chemokine (MDC), interleukin-10 (IL-10), endothelin-1 (ET-1), C-C motif chemokine ligand 20 (CCL20), calcitonin, and thromboxane (TXA2) changed before and after occupational hand-arm vibration exposure. 38 full-time shift workers exposed to hand-arm vibration were recruited. All the participants underwent medical examinations regarding symptoms of Raynaud's phenomena. In 29 of the participants, the concentration of IL-33, MDC, IL-10, ET-1, CCL20, calcitonin, and TXA2 was measured before and after a workday. There was a significant increase in ET-1 and calcitonin concentration and a decrease in the CCL20 concentration after the work shift in all participants. In the group suffering from VWF, but not in the non-VWF group, MDC was statistically significantly lower before the work shift (p = .023). The VWF group also showed a significant increase in MDC after the work shift. Exposure to occupational hand-arm vibration is associated with changes in ET-1, calcitonin, and MDC concentration in subjects suffering from vibration white fingers, suggesting a role of these biomarkers in the pathophysiology of this condition.

Relationship between nailfold videocapillaroscopic findings and cardiovascular risk factors.

BACKGROUND: Nailfold Videocapillaroscopy (NVC) is a valuable tool in the differential diagnosis of Raynaud's phenomenon (RP), present in certain Rheumatic diseases (RD). Knowing that many people have cardiovascular risk factors (CVRF), the main objective was to demonstrate that CVRF and carotid plaques produce NVC alterations. METHODS: Cross-sectional unicentric study carried out from 2020 to 2023. Four groups were formed: subjects with RD and RP, participants with RD without RP, subjects with RP without RD and finally participants without RP or RD (study group). Each subject exhibiting CVRF presented only a single risk factor. The variables collected were: sociodemographic, CVRF (diabetes, tobacco, alcohol (ALC), obesity (OBE), dyslipidemia and arterial hypertension (AH)), diseases, RP, treatments, tortuosities and NVC alterations (ramified capillaries, enlarged capillaries, giant capillaries, haemorrhages and density loss) and carotid ultrasound (CU). RESULTS: 402 subjects were included (76 % women, mean age 51 ± 16 years), 67 % had CVRF, 50 % RP and 38 % RD. Tortuosities were present in 100 % of CVRF participants. A statistically significant association was found between the presence of CVRF and all the NVC alterations: ramified capillaries (OR = 95.6), enlarged capillaries (OR = 59.2), giant capillaries (OR = 8.32), haemorrhages (OR = 17.6) and density loss (OR = 14.4). In particular, an association was found between giant capillaries with AH (p = 0,008) and OBE (p ã€ˆ0,001), and haemorrhages and density loss with ALC and OBE (p < 0,001). On the other hand, 40 subjects presented CU plaques (9.9 %), associated with enlarged capillaries (OR = 8.08), haemorrhages (OR = 4.04) and ramified capillaries (OR = 3.01). The pathological intima-media thickness was also associated with haemorrhages (OR = 3.14). CONCLUSIONS: There is a clear association between CVRF and ultrasound atherosclerotic findings in carotid with NVC alterations. These findings are of special interest for a correct NVC interpretation and to avoid false positives in the diagnosis of primary and secondary RP.

Neurofascialvascular training for the treatment of Raynaud's phenomenon: A case report.

Primary Raynaud's phenomenon (PRP) is characterised by episodic, reversible, and disabling vasospasms of the peripheral arteries. In the most severe cases, it can lead to ulceration of the fingers and toes. Neuro fascial VascularTraining (NFVT) is a novel therapeutic approach for treating PRP. NFVT aims to enhance peripheral circulation and stimulate the autonomic nervous system (ANS) by engaging multiple physiological mechanisms simultaneously. This integrated approach works to reduce vasospasms and alleviate associated symptoms through neurodynamic and myofascial interventions. A 54-year-old woman, who has experienced pain and hypoesthesia in her hands for 9 years, received a diagnosis of PRP without systemic sclerosis in 2014. The patient reported daily colour changes in her fingers, along with pain and a temporary decrease in tactile sensitivity. The patient engaged in ten 30-minute exercise sessions, and the clinical outcomes were assessed based on several parameters. These included the frequency and duration of vasospastic attacks, evaluated using the Raynaud Condition Score, as well as pain and tingling, measured through the daily Numeric Rating Scale. The Composite Autonomic Symptom Score (COMPASS 31) was utilised to assess dysautonomia, while the frequency of medication use and the Disabilities of the Arm, Shoulder, and Hand questionnaire were also considered. The results indicated a significant improvement in symptoms. NFVT improved symptoms and motor dysfunction in a patient with Raynaud's syndrome, demonstrating how NFVT can increase peripheral blood flow, stimulate the ANS, and improve symptoms in PRP.

Non-arterial line cardiac output calculation misclassifies exercise pulmonary hypertension and increases risk of data loss particularly in black, scleroderma and Raynaud's patients during invasive exercise testing.

BACKGROUND: The direct Fick principle is the standard for calculating cardiac output (CO) to detect CO-dependent conditions like exercise pulmonary hypertension (ePH). Fick COarterial incorporates arterial haemoglobin (Hba) and oxygen saturation (S aO2 ) with oxygen consumption from exercise testing, while Fick COnon-arterial substitutes mixed venous haemoglobin (Hbmv) and peripheral oxygen saturation (S pO2 ) in the absence of an arterial line. The decision to employ an arterial catheter for exercise testing varies, and discrepancies in oxygen saturation and haemoglobin between arterial and non-arterial methods may lead to differences in Fick CO, potentially affecting ePH classification. METHODS: We performed a retrospective analysis of 296 consecutive invasive cardiopulmonary exercise testing (iCPET) studies comparing oxygen saturation from pulse oximetry (S pO2 ) and radial arterial (S aO2 ), Hba and Hbmv, and CO calculated with arterial (COarterial) and non-arterial (COnon-arterial) values. We assessed the risk of misclassification of pre- and post-capillary ePH and data loss due to inaccurate S pO2 . RESULTS: When considering all stages from rest to peak exercise, Hba and Hbmv demonstrated high correlation, while S pO2 and S aO2 as well as COarterial and COnon-arterial demonstrated low correlation. Data loss was significantly higher across all stages of exercise for S pO2 (n=346/1926 (18%)) compared to S aO2 (n=17/1923 (0.88%)). We found that pre- and post-capillary ePH were misclassified as COnon-arterial data (n=7/41 (17.1%) and n=2/23 (8.7%), respectively). Patients with scleroderma and/or Raynaud's (n=11/33 (33.3%)) and black patients (n=6/19 (31.6%)) had more S pO2 data loss. CONCLUSION: Reliance upon S pO2 during invasive exercise testing results in the misclassification of pre- and post-capillary ePH, and unmeasurable S pO2 for black, scleroderma and Raynaud's patients can preclude accurate exercise calculations, thus limiting the diagnostic and prognostic value of invasive exercise testing without an arterial line.

Insights into systemic lupus erythematosus: a retrospective observational study of clinical features, autoantibodies, and gender-related differences.

This study aims to analyze the clinical and immunologic features of SLE in Jordan, while also investigating the impact of age and gender on disease presentation. The study included 275 patients diagnosed with SLE. Data were collected through meticulous patient interviews and thorough examination of patient hospital records. The cohort exhibited a mean age of 36.8 ± 12.9 years, with an average disease duration of 7.0 ± 7.8 years. The mean age at diagnosis was 29.9 ± 12.1 years, and the female to male ratio was 7.8:1. The most frequently observed symptoms were arthralgia (90.2%), fatigue (80.7%), hematologic manifestations (62%), photosensitivity (60.7%), Raynaud's phenomenon (53.5%), and malar rash (50.9%). The frequencies of various autoantibodies were as follows: ANA (96.7%), anti-dsDNA (39.6%), anti-SSA/Ro (32.8%), anti-Sm (21.8%), anti-U1-RNP (20.6%), and anti-SSB/La (15.5%). Male patients tended to receive a diagnosis at a younger age and exhibited a higher likelihood of experiencing severe manifestations compared to females. Additionally, juvenile onset patients demonstrated an increased likelihood of fever, photosensitivity, myositis, and anti-dsDNA autoantibodies, while adult onset patients were more predisposed to having anti-Ro, anti-La, and RF autoantibodies. This study reveals that the most prevalent manifestations of SLE in the Jordanian cohort encompassed arthralgia, fatigue, and hematologic manifestations. The prevalence of alopecia and Raynaud's phenomenon exceeded that observed in other published cohorts, while arthritis and discoid rash were less frequently encountered. The study highlights that males are more susceptible to developing severe manifestations of SLE compared to females.

Can we define difficult-to-treat systemic sclerosis?

INTRODUCTION: Systemic sclerosis (SSc) is a chronic autoimmune rheumatic disease characterized by microvascular alterations, immunopathology, and widespread fibrosis involving various organs. It is considered difficult to treat due to several reasons: complex pathogenesis, heterogeneity, late diagnosis, limited treatment options for certain organ manifestations, lack of personalized medicine. AREAS COVERED: This review presents the heterogeneity, survival and organ manifestations with their risk factors of systemic sclerosis and their current treatment options, while drawing attention to difficult-to-treat forms of the disease, based on literature indexed in PubMed. EXPERT OPINION: Despite recent advances in the management of SSc over the last decades, the disease presents significant morbidity and mortality. Although available treatment protocols brought significant advancements in terms of survival in SSc-associated interstitial lung disease and pulmonary arterial hypertension, less success has been achieved in the treatment of Raynaud's phenomenon and digital ulcers and the results are modest in case of heart, gastrointestinal, and renal manifestations. There are patients who do not respond to treatment and deteriorate even with adequate therapy. They can be considered difficult-to treat (D2T) cases. We have created a possible score system based on the individual organ manifestations and highlighted treatment options for the D2T SSc category.

Raynaud's phenomenon of the nipple during breastfeeding: A case series. / Fenómeno de Raynaud en el pezón durante la lactancia: serie de casos.

Raynaud's phenomenon consists of excessive contraction of the blood vessels in response to various stimuli; although it usually affects the extremities, other locations are less frequently involved. This study focused on describing the characteristics of a series of women with Raynaud's phenomenon of the nipple. Through medical record review and direct communication with patients, data from 12 women diagnosed with Raynaud's phenomenon of the nipple between 2016 and 2023 were collected and analyzed. The following variables were assessed: age, symptoms, triggering factors, treatment, and duration of symptoms. In this case series, Raynaud's phenomenon of the nipple in breastfeeding women was more common among primiparous women around 10 days after delivery; pain was severe and, in most cases, improved with local and/or drug treatment, and did not limit the duration of breastfeeding.

El fenómeno de Raynaud consiste en la contracción excesiva de los vasos sanguíneos en respuesta a diversos estímulos y, si bien suele comprometer las extremidades, existen otras localizaciones menos frecuentemente afectadas. Este trabajo se enfoca en describir las características de una serie de mujeres con fenómeno de Raynaud en el pezón. Mediante revisión de historias clínicas y comunicación directa con las pacientes, se recopilaron y analizaron los datos de 12 mujeres con Raynaud del pezón entre 2016 y 2023. Se evaluaron variables como edad, síntomas, desencadenantes, tratamientos y duración de los síntomas. En esta serie de casos, el fenómeno de Raynaud del pezón en mujeres lactantes se manifestó con mayor frecuencia en primigestas alrededor del décimo día posparto; el dolor fue intenso, en la mayoría mejoró con tratamientos locales y/o farmacológicos, y no limitó la duración de la lactancia materna.

Association of neutrophil extracellular trap levels with Raynaud's phenomenon, glomerulonephritis and disease index score in SLE patients from Brazil.

Neutrophil extracellular traps (NETs) are cell-extruded DNA strands coated with neutrophils' nuclear proteins and enzymes from cytotoxic granules, produced by NETosis, a cell death pathway. They perform an important defensive role in innate immunity, but their increased production and/or inefficient degradation expose new antigens, such as DNA or citrullinated histone peptides, triggering autoimmunity. This study aimed to access possible associations between serum NETs levels with epidemiological, clinical, and serological data from a well-characterized SLE Brazilian patients' cohort. NET levels were evaluated in one hundred seventy serum samples of patients with Systemic Lupus Erythematosus (SLE) using an Immunoassay. Univariate and multivariate binary logistic regression used clinical patients' data as independent variables. Parametric and non-parametric tests compared log10 base serum NET levels transformed between patients' groups. SLE patients were also dichotomized into "High serum NET levels" and "Low serum NET levels" groups. All analyses were performed in R language 4.1.2, and p < 0.05 were considered significant. Increased susceptibility for high serum NET levels was observed in SLE patients with Raynaud's phenomenon (OR = 2.30, 95 % CI = 1.06-5.21 and p = 0.039), independently of any other risk factor. Also, SLE patients with Raynaud's phenomenon presented higher mean NET serum levels (mean = -0.13 vs. -0.51, p = 0.01). In addition, higher mean NET serum levels were associated with glomerulonephritis (mean = -0.45 vs. -0.12, p = 0.03). Ultimately, the SLEDAI index scored higher in the high NETs serum levels group (median = 2.0 vs. 0.0, p = 6 × 10-3). The formation of NETs might be implicated in Raynaud's phenomenon, glomerulonephritis, and disease index score in SLE patients. Our results highlight the importance of serum NET levels as a possible therapeutical target to modulate the clinical course of SLE.

Rare combo: moyamoya and lupus in men.

Moyamoya syndrome (MMS) is a rare, chronic, progressive cerebrovascular disorder characterized by stenosis at the apices of the intracranial internal carotid arteries, including the proximal anterior cerebral arteries and middle cerebral arteries. Cerebral angiography images are used for detection through measurement. Systemic lupus erythematosus (SLE) is an autoimmune disease that can cause multisystemic involvement. The coexistence of SLE and MMS has been rarely reported in the literature. A 46-year-old male patient with malar rash, Raynaud phenomenon presented to the hospital with a complaint of weakness in the left lower extremity, which began 3 days before the date of the visit. In the diffusion magnetic resonance imaging, multiple diffusion restrictions were observed in the right frontal region. The patient underwent MR angiography, revealing stenosis in the terminal and supraclinoid segments of the right internal carotid artery, which made us consider moyamoya disease. This patient, with a malar rash and Raynaud's, a positive antibody profile, was diagnosed as a male with SLE accompanied by MMS.

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.

Re-evaluation of nailfold capillaroscopy in discriminating primary from secondary Raynaud's phenomenon and in predicting systemic sclerosis: a randomised observational prospective cohort study.

BACKGROUND: Primary Raynaud's phenomenon (pRP) is difficult to distinguish from secondary (sRP). Although nailfold capillaroscopy (NFC) may detect early alterations, no universal criteria yet discriminate between pRP from sRP. OBJECTIVES: To create and validate two NFC scores that could distinguish pRP from sRP and that could predict systemic sclerosis (SSc), respectively. METHODS: We performed NFC on two separate cohorts with isolated RP, and recorded number of capillaries per field, enlarged/giant capillaries, crossed/bizarre patterns, microhemorrhages, neoangiogenesis, rarefaction, edema, blood flow velocity, stasis. By multivariate regression analysis, we evaluated the adjusted prognostic role of these features in a derivation cohort of 656 patients. Results were used to construct algorithm-based prognostic scores (A and B). These scores were then tested on a confirmation cohort of 219 patients. RESULTS: Score A was unable to discriminate sRP from pRP (low negative predictive values with high positive predictive values for any cut-point); score B was unable to discriminate progression to SSc or a SSc-spectrum disorder (low positive predictive values with high negative predictive values for lower cut-points). CONCLUSION: NFC patterns, believed as specific, showed low discriminatory power and on their own are unable to reliably discriminate sRP from pRP or predict evolution to SSc.

Non-contrast MRI of micro-vascularity of the feet and toes.

PURPOSE: This study aimed to develop novel non-contrast MR perfusion techniques for assessing micro-vascularity of the foot in human subjects. METHODS: All experiments were performed on a clinical 3 T scanner using arterial spin labeling (ASL). Seven healthy subjects (30-72 years old, 5 males and 2 females) were enrolled and bilateral feet were imaged with tag-on and tag-off alternating inversion recovery spin labeling for determining micro-vascularity. We compared an ASL technique with 1-tag against 4-tag pulses. For perfusion, we determined signal increase ratio (SIR) at varying inversion times (TI) from 0.5 to 2 s. SIR versus TI data were fit to determine perfusion metrics of peak height (PH), time to peak (TTP), full width at half maximum (FWHM), area under the curve (AUC), and apparent blood flow (aBF) in the distal foot and individual toes. Using analysis of variance (ANOVA), effects of tag pulse and region of interest (ROI) on the mean perfusion metrics were assessed. In addition, a 4-tag pulse perfusion experiment was performed on patients with peripheral artery disease (PAD) and Raynaud's disease. RESULTS: Using our MR perfusion techniques, SIR versus TI data showed well-defined leading and trailing edges, with a peak near TI of 0.75-1.0 s and subsiding quickly to near zero by TI of 2 s, particularly when 4-tag pulses were used. When imaged with 4-tag pulse, we found significantly greater values in perfusion metrics, as compared to 1-tag pulse. The patients with PAD and Raynaud's disease showed a reduced or scattered perfusion curves compared to the healthy control. CONCLUSION: MR perfusion imaging of the distal foot shows greater SIR and perfusion metrics with the 4-tag pulse compared to the 1-tag pulse technique. This will likely benefit those with low perfusion due to aging, PAD, diabetic foot, and other vascular diseases.