The association between tobacco smoking and systolic toe pressures in active foot ulceration

Smoking may increase the risk of diabetic foot disease and ulceration. It does so by impairing glycaemic control and promoting the formation of advanced glycated end-products. Additionally, smoking is known to delay surgical wound healing and accelerate peripheral arterial disease. We aimed to determine whether toe pressures differed in smokers with a foot ulcer, when compared to non-smokers and ex-smokers, as well as ulcer outcomes at 12 months, among patients attending Blacktown Hospital High Risk Foot Service (HRFS). This study is a retrospective analysis of our prospectively collected clinic database. Eligible participants were adults attending the HRFS between June 2020 and April 2022. Participants were included if they had an ulcer, at least one systolic toe pressure reading completed at their initial visit and attended at least one follow-up visit. Participants were followed until healing, loss to follow-up or a minimum of 12 months. A total of 195 participants were included; 36 smokers, 82 ex-smokers, and 77 controls who had never smoked. Smoking status was by self-report. Current smokers were significantly younger at initial presentation (p = .002) and tended towards lower socioeconomic status (p = .067). Current smokers were significantly more likely to have ischaemic grade 3 toe pressures (< 30 mmHg) of their left foot (p = .027), suggestive of reduced perfusion. At the end of follow up period, smokers had the numerically highest rates of minor amputations. In conclusion, smokers ulcerate younger and are more likely to have grade 3 ischaemia. Collecting information about the brachial artery pressures and the time since the last cigarette may clarify any relationship between smoking and toe pressures.Trial registration: WSLHD HREC ethics approval 2111-02 and ANZCTR registration 382470. Registered on 15/09/2021.

Emerging Issues and Initial Insights into Bacterial Biofilms: From Orthopedic Infection to Metabolomics

Bacterial biofilms, enigmatic communities of microorganisms enclosed in an extracellular matrix, still represent an open challenge in many clinical contexts, including orthopedics, where biofilm-associated bone and joint infections remain the main cause of implant failure. This study explores the scenario of biofilm infections, with a focus on those related to orthopedic implants, highlighting recently emerged substantial aspects of the pathogenesis and their potential repercussions on the clinic, as well as the progress and gaps that still exist in the diagnostics and management of these infections. The classic mechanisms through which biofilms form and the more recently proposed new ones are depicted. The ways in which bacteria hide, become impenetrable to antibiotics, and evade the immune defenses, creating reservoirs of bacteria difficult to detect and reach, are delineated, such as bacterial dormancy within biofilms, entry into host cells, and penetration into bone canaliculi. New findings on biofilm formation with host components are presented. The article also delves into the emerging and critical concept of immunometabolism, a key function of immune cells that biofilm interferes with. The growing potential of biofilm metabolomics in the diagnosis and therapy of biofilm infections is highlighted, referring to the latest research.

Development of a Tissue Oxygenation Flow-Based Index Toward Discerning the Healing Status in Diabetic Foot Ulcers

Objective: The objective of this study is to characterize breath-hold (BH)-induced oxygenation changes in diabetic foot ulcers (DFUs) and develop an oxygenation flow index (OFI) to discern nonhealing from healing DFUs. Approach: The imaging approach utilizes an innovative BH stimulus that induces vasoconstriction and measures for altering oxygenation flow in and around the tissues of DFUs and controls. The modified Beer-Lambert law was utilized to calculate hemoglobin-based spatiotemporal oxygenation maps in terms of oxygen saturation. Results: We found controls had synchronous BH-induced oxygenation changes across the dorsal (OFI: 29.0%) and plantar (OFI: 57.6%) aspects of the foot. Nonhealing DFUs, however, had less synchronous BH-induced oxygenation changes (OFI <28%). In addition, two complicated healing DFU cases, or cases with underlying issues or poor long-term healing outcomes, were observed to have OFIs <28%. Innovation: An OFI was developed to differentiate nonhealing DFUs from healing DFUs using a single, noncontact, near-infrared optical scanner for spatiotemporal oxygenation monitoring. The OFI has potential to provide immediate feedback on the microcirculation in DFUs, through hemoglobin-based oxygenation parameters. Conclusion: A preliminary threshold (OFI <28%) could differentiate nonhealing and complicated DFUs from healing DFUs. The overall oxygenation flow pattern was less synchronous (or the OFI value reduced) in the nonwound areas of the feet that were nonhealing. In other words, the reduced OFI value (<28%) in the entire foot, excluding the wound region is a possible indicator that the wound may not heal.

Does the advantage of transcutaneous oximetry measurements in diabetic foot ulcer apply equally to free flap reconstruction?

BACKGROUND

Transcutaneous oxygen pressure (TcpO₂) is a precise method for determining oxygen perfusion in wounded tissues. The device uses either electrochemical or optical sensors.

AIM

To evaluate the usefulness of TcpO₂ measurements on free flaps (FFs) in diabetic foot ulcers (DFUs).

METHODS

TcpO₂ was measured in 17 patients with DFUs who underwent anterolateral thigh (ALT)-FF surgery and compared with 30 patients with DFU without FF surgery.

RESULTS

Significant differences were observed in the ankle-brachial index; duration of diabetes; and haemoglobin, creatinine, and C-reactive protein levels between the two groups. TcpO₂ values were similar between two groups except on postoperative days 30 and 60 when the values in the ALT-FF group remained < 30 mmHg and did not increase > 50 mmHg.

CONCLUSION

Even if the flap is clinically stable, sympathectomy due to adventitia stripping during anastomosis and arteriovenous shunt progression due to diabetic polyneuropathy could lead to low TcpO₂ values in the ALT-FF owing to its thick fat tissues, which is supported by the slow recovery of the sympathetic tone following FF. Therefore, TcpO₂ measurements in patients with DFU who underwent FF reconstruction may be less accurate than in those who did not.

Analyses of transcutaneous oxygen pressure values stratified for foot angiosomes to predict diabetic foot ulcer healing

AIMS

Previous research suggested that diabetic foot ulcer (DFU) location could affect transcutaneous oxygen pressure (TcPO2) values following the angiosome concept. Up to our knowledge no studies have yet analyzed if the location of a diabetic foot ulcer can be a confounding factor that modifies TcPO2 values. The primary aim of this study was to compare the potential healing prognosis of TcPO2 differentiated for diabetic foot ulcers in different angiosome locations.

METHODS

a 2-years observational cohort prospective study was performed in 81 patients with diabetic foot ulcers. Transcutaneous oxygen pressure measurements were performed at baseline by placing the electrode on two different angiosomes: dorsal zone of the foot (dorsalis pedis angiosome) and between the navicular bone and the tibial malleolus (posterior tibial angiosome). The main outcome was establishing the effectiveness of TcPO2 measurements (dorsalis pedis angiosome and posterior tibial angiosome) for predicting DFU healing.

RESULTS

Transcutaneous oxygen pressure probe placed in the dorsum of the foot (dorsalis pedis angiosome) yielded a sensitivity (S) of 95 % and specificity (SP) of 73 %, and an area under the curve (AUC) of 0.902 (p < 0.001 [0.84-0.96]) for ulcers located in the forefoot and toes; while TcPO2 placed in the posterior tibial angiosome yielded an S of 100 % and SP of 85 % and an AUC of 0.894 (p < 0.001 [0-822-0.966]) for DFU located in the midfoot and heel.

CONCLUSION

This study suggests that angiosome-guided TcPO2 contributes to a prognosis of successful foot ulcer healing.

Diabetic Foot Ulcer Imaging: An Overview and Future Directions

Diabetic foot ulcers (DFUs) affect one in every three people with diabetes. Imaging plays a vital role in objectively complementing the gold-standard visual yet subjective clinical assessments of DFUs during the wound treatment process. Herein, an overview of the various imaging techniques used to image DFUs is summarized. Conventional imaging modalities (e.g., computed tomography, magnetic resonance imaging, positron emission tomography, single-photon emitted computed tomography, and ultrasound) are used to diagnose infections, impact on the bones, foot deformities, and blood flow in patients with DFUs. Transcutaneous oximetry is a gold standard to assess perfusion in DFU cases with vascular issues. For a wound to heal, an adequate oxygen supply is needed to facilitate reparative processes. Several optical imaging modalities can assess tissue oxygenation changes in and around the wounds apart from perfusion measurements. These include hyperspectral imaging, multispectral imaging, diffuse reflectance spectroscopy, near-infrared (NIR) spectroscopy, laser Doppler flowmetry or imaging, and spatial frequency domain imaging. While perfusion measurements are dynamically monitored at point locations, tissue oxygenation measurements are static two-dimensional spatial maps. Recently, we developed a spatio-temporal NIR-based tissue oxygenation imaging approach to map for the extent of asynchrony in the oxygenation flow patterns in and around DFUs. Researchers also measure other parameters such as thermal maps, bacterial infections (from fluorescence maps), pH, collagen, and trans-epidermal water loss to assess DFUs. A future direction for DFU imaging would ideally be a low-cost, portable, multi-modal imaging platform that can provide a visual and physiological assessment of wounds for comprehensive wound care intervention and management.

Upper arm versus forearm transcutaneous oximetry during upper limb abduction in patients with suspected thoracic outlet syndrome

Context: Thoracic outlet syndrome (TOS) is common among athletes and should be considered as being of arterial origin only if patients have “clinical symptoms due to documented symptomatic ischemia.” We previously reported that upper limb ischemia can be documented with DROPm (minimal value of limb changes minus chest changes) from transcutaneous oximetry (TcpO2) in TOS.

Purpose: We aimed to test the hypothesised that forearm (F-) DROPm would better detect symptoms associated with arterial compression during abduction than upper arm (U-) DROPm, and that the thresholds would differ.

Methods: We studied 175 patients (retrospective analysis of a cross-sectional acquired database) with simultaneous F-TcpO2 and U-TcpO2 recordings on both upper limbs, and considered tests to be positive (CS+) when upper limb symptoms were associated with ipsilateral arterial compression on either ultrasound or angiography. We determined the threshold and diagnostic performance with a receiver operating characteristic (ROC) curve analysis and calculation of the area under the ROC curve (AUROC) for absolute resting TcpO2 and DROPm values to detect CS+. For all tests, a two-tailed p &lt; 0.05 was considered indicative of statistical significance.

Results: In the 350 upper-limbs, while resting U-TcpO2 and resting F-TcpO2 were not predictive of CS + results, the AUROCs were 0.68 ± 0.03 vs. 0.69 ± 0.03 (both p &lt; 0.01), with the thresholds being −7.5 vs. −14.5 mmHg for the detection of CS + results for U-DROPm vs. F-DROPm respectively.

Conclusion: In patients with suspected TOS, TcpO2 can be used for detecting upper limb arterial compression and/or symptoms during arm abduction, provided that different thresholds are used for U-DROPm and F-DROPm.

Clinical Trial Registration:ClinicalTrials.gov, identifier NCT04376177.

Stem Cell-Based Therapeutic Strategies in Diabetic Wound Healing

Impaired wound healing and especially the “all-too-common” occurrence of associated diabetic foot ulcers (DFU) are becoming an increasingly urgent and deteriorating healthcare issue, which drastically impact the quality of life and further heighten the risks of infection and amputation in patients with diabetes mellitus. Amongst the multifactorial wound healing determinants, glycemic dysregulation has been identified to be the primary casual factor of poor wound healing. Unfortunately, current therapeutic modalities merely serve as moderate symptomatic relieves but often fail to completely restore the wound site to its pre-injury state and prevent further recurrence. Stem cell-based therapeutics have been employed for its promising potential to address the root of the problem as they not only exhibit the capacity for self-renewal and differentiation towards multiple lineages, but also have been disclosed to participate in mediating variant growth factors and cytokines. Herein we review the current literatures on the therapeutic benefits of using various kinds of stem cells, including embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), mesenchymal stem cells (MSCs), and adipose-derived stem cells (ASCs) in diabetic wound healing by searching on the PubMed® Database for publications. This study shall serve as an overview of the current body of research with particular focus on autologous ASCs and the laboratory expandable iPSCs in hope of shedding more light on this attractive therapy so as to elevate the efficacy of wound healing that is almost always compromised in diabetic patients.

Analysis of peripheral arterial disease (PAD) patients by laser speckle measurement techniques

Diabetic foot is a well-known problem among patients suffering from peripheral arterial diseases (PAD). This article presents an optical sensor for contactless measurement of the anatomical site based on laser speckle techniques. The sensor illuminates the inspected tissue and analyzes the captured back-reflected light from the time-changing speckle patterns. An occlusion test was implemented to provide a statistical parameter to differentiate between a low perfused and a healthy foot. A clinical study of 15 subjects was conducted. The video was analyzed by two methods: dynamic laser speckle (DLS) and laser speckle contrast analysis (LASCA). Data analysis included several classification models, where the KNN model exhibited maximum performance. These findings suggest that a simple and inexpensive system for PAD monitoring can be designed for home use and/or in community clinics.

Preoperative Transcutaneous Oxygen Perfusion Measurements in Predicting Atraumatic Wound Healing After Major Lower Extremity Amputation

This study examined the correlation between preoperative transcutaneous oxygen perfusion (TcPO₂) measurement and the success of wound healing after major lower extremity amputation. There is no validated consensus on how to accurately determine appropriate amputation levels. A TcPO₂ greater than 30 to 40 mm Hg is widely cited as a positive predictor of postoperative wound healing, but its validity has not been well defined. A retrospective chart review was performed for patients who underwent above-knee amputation (AKA), through-knee amputation, or below-knee amputation (BKA) at a single institution from 2012 to 2018 with preoperative TcPO₂ values and a minimum 30-day postoperative clinical follow-up. This review yielded 141 total amputations: 93 BKAs, 6 through-knee amputations, and 42 AKAs. Fifty-five amputations were unsuccessful, defined by postoperative wound dehiscence or infection. Of these, 37 were BKAs, 4 were through-knee amputations, and 14 were AKAs. There was a significant difference in preoperative TcPO₂ between the successful and unsuccessful amputations, at 46.2 and 38.3 mm Hg, respectively (P=.02). A TcPO₂ of 30 to 40 mm Hg showed a 68.8% success rate, and a TcPO₂ of less than 20 mm Hg showed an 18.2% success rate. A receiver operating characteristic curve for TcPO₂ predicting amputation success had an area under the curve of 0.53 for AKAs and 0.61 for BKAs; the diagnostic ability is far from prognostic. There is no linear association between TcPO₂ and success rate. A TcPO₂ of less than 20 mm Hg has a high positive predictive value for failure, but higher levels are not 100% predictive of wound healing success after amputation, as previously reported. [Orthopedics. 2022;45(3):174-180.].

Wearable Bioelectronics for Chronic Wound Management

Chronic wounds are a major healthcare issue and can adversely affect the lives of millions of patients around the world. The current wound management strategies have limited clinical efficacy due to labor-intensive lab analysis requirements, need for clinicians' experiences, long-term and frequent interventions, limiting therapeutic efficiency and applicability. The growing field of flexible bioelectronics enables a great potential for personalized wound care owing to its advantages such as wearability, low-cost, and rapid and simple application. Herein, recent advances in the development of wearable bioelectronics for monitoring and management of chronic wounds are comprehensively reviewed. First, the design principles and the key features of bioelectronics that can adapt to the unique wound milieu features are introduced. Next, the current state of wound biosensors and on-demand therapeutic systems are summarized and highlighted. Furthermore, we discuss the design criteria of the integrated closed loop devices. Finally, the future perspectives and challenges in wearable bioelectronics for wound care are discussed.

Assessing the inflammatory response to in vitro polymicrobial wound biofilms in a skin epidermis model

Wounds can commonly become infected with polymicrobial biofilms containing bacterial and fungal microorganisms. Microbial colonization of the wound can interfere with sufficient healing and repair, leading to high rates of chronicity in certain individuals, which can have a huge socioeconomic burden worldwide. One route for alleviating biofilm formation in chronic wounds is sufficient treatment of the infected area with topical wound washes and ointments. Thus, the primary aim here was to create a complex in vitro biofilm model containing a range of microorganisms commonly isolated from the infected wound milieu. These polymicrobial biofilms were treated with three conventional anti-biofilm wound washes, chlorhexidine (CHX), povidone-iodine (PVP-I), and hydrogen peroxide (H₂O₂), and efficacy against the microorganisms assessed using live/dead qPCR. All treatments reduced the viability of the biofilms, although H₂O₂ was found to be the most effective treatment modality. These biofilms were then co-cultured with 3D skin epidermis to assess the inflammatory profile within the tissue. A detailed transcriptional and proteomic profile of the epidermis was gathered following biofilm stimulation. At the transcriptional level, all treatments reduced the expression of inflammatory markers back to baseline (untreated tissue controls). Olink technology revealed a unique proteomic response in the tissue following stimulation with untreated and CHX-treated biofilms. This highlights treatment choice for clinicians could be dictated by how the tissue responds to such biofilm treatment, and not merely how effective the treatment is in killing the biofilm.

Vascular Assessment in Patients With a Lower Limb Wound: A Correlational Study of Photoplethysmography and Laser Doppler Flowmetry Toe Pressure Techniques

BACKGROUND

Vascular assessment of the lower limbs is essential in patients with diabetes. In the presence of noncompressible arteries, the ankle brachial index (ABI) can either be inconclusive or provide false-positive results. Toe pressure measurement has been suggested as an alternative as a noninvasive method for detecting peripheral arterial disease (PAD). Toe pressure measurement can be performed either by photoplethysmography (PPG) or by Laser Doppler flowmetry (LDF). The aim of this study was to determine correlations between the two techniques in order to promote the use of PPG in clinical practice.

METHODS

This was a prospective correlational study of 108 consecutive recruited adult patients, with and without diabetes, with at least one lower limb wound from a University-affiliated hospital wound care clinic. Toe pressure measurements were both performed with PPG and LDF devices.

RESULTS

Mean toe pressure values for PPG and LDF were, respectively, 83.7 (SD 35.4) and 79.5 (SD 32.0) mmHg (with a paired t-test 3.969, P < 0.01). In patients with at least one lower limb wound, a strong linear relation was found between PPG and LDF toe pressure techniques with a Pearson's r correlation coefficient of 0.920 (P < 0.001).

CONCLUSIONS

PPG and LDF toe pressure techniques are equivalent in patients with at least one lower limb wound, irrespective of the presence of diabetes. Therefore, in the presence of an ABI with inconclusive results, such as in a patient with noncompressible vessels, both toe pressure techniques can be used for assessing the vascular supply of the lower limb with a wound.

Immunometabolism in biofilm infection: lessons from cancer

BACKGROUND

Biofilm is a community of bacteria embedded in an extracellular matrix, which can colonize different human cells and tissues and subvert the host immune reactions by preventing immune detection and polarizing the immune reactions towards an anti-inflammatory state, promoting the persistence of biofilm-embedded bacteria in the host.

MAIN BODY OF THE MANUSCRIPT

It is now well established that the function of immune cells is ultimately mediated by cellular metabolism. The immune cells are stimulated to regulate their immune functions upon sensing danger signals. Recent studies have determined that immune cells often display distinct metabolic alterations that impair their immune responses when triggered. Such metabolic reprogramming and its physiological implications are well established in cancer situations. In bacterial infections, immuno-metabolic evaluations have primarily focused on macrophages and neutrophils in the planktonic growth mode.

CONCLUSION

Based on differences in inflammatory reactions of macrophages and neutrophils in planktonic- versus biofilm-associated bacterial infections, studies must also consider the metabolic functions of immune cells against biofilm infections. The profound characterization of the metabolic and immune cell reactions could offer exciting novel targets for antibiofilm therapy.

Recent Insights into the Measurement of Carbon Dioxide Concentrations for Clinical Practice in Respiratory Medicine

In the field of respiratory clinical practice, the importance of measuring carbon dioxide (CO2) concentrations cannot be overemphasized. Within the body, assessment of the arterial partial pressure of CO2 (PaCO2) has been the gold standard for many decades. Non-invasive assessments are usually predicated on the measurement of CO2 concentrations in the air, usually using an infrared analyzer, and these data are clearly important regarding climate changes as well as regulations of air quality in buildings to ascertain adequate ventilation. Measurements of CO2 production with oxygen consumption yield important indices such as the respiratory quotient and estimates of energy expenditure, which may be used for further investigation in the various fields of metabolism, obesity, sleep disorders, and lifestyle-related issues. Measures of PaCO2 are nowadays performed using the Severinghaus electrode in arterial blood or in arterialized capillary blood, while the same electrode system has been modified to enable relatively accurate non-invasive monitoring of the transcutaneous partial pressure of CO2 (PtcCO2). PtcCO2 monitoring during sleep can be helpful for evaluating sleep apnea syndrome, particularly in children. End-tidal PCO2 is inferior to PtcCO2 as far as accuracy, but it provides breath-by-breath estimates of respiratory gas exchange, while PtcCO2 reflects temporal trends in alveolar ventilation. The frequency of monitoring end-tidal PCO2 has markedly increased in light of its multiple applications (e.g., verify endotracheal intubation, anesthesia or mechanical ventilation, exercise testing, respiratory patterning during sleep, etc.).

Oxygen-Sensing Biomaterial Construct for Clinical Monitoring of Wound Healing

OBJECTIVE

Oxygen is essential to wound healing; therefore, accurate monitoring can guide clinical decisions. Clinical wound assessment is often subjective, and tools to monitor wound oxygen are typically expensive, indirect, and highly variable. This study demonstrates the utility of a novel, low-cost oxygen-sensing thin film for serial assessment of wound oxygenation.

DESIGN

Dual-layer films were fabricated with boron oxygen-sensing nanoparticles (BNPs) impregnated into a chitosan-polycaprolactone layer for direct wound bed contact with a relatively oxygen impermeable calcium alginate surface layer. The BNPs are a dual-emissive difluoroboron β-diketonate dye incorporated into poly(lactic acid) nanoparticles. Under UV excitation, the BNPs emit fluorescence based on concentration and oxygen-sensitive phosphorescence. The fluorescence/phosphorescence ratio is directly proportional to oxygen concentration.

METHODS

A series of in vitro oxygen challenges and in vivo murine and porcine wound healing models were used to validate the utility of the film in sensing wound oxygenation.

MAIN RESULTS

In vitro testing demonstrated the oxygen-sensing capability of the BNP film and its ability to shield ambient oxygen to isolate wound oxygen. In vivo testing demonstrated the ability of the film to accurately monitor relative oxygen changes in a murine wound over time, measuring a 22% fluorescence/phosphorescence increase during acute healing.

CONCLUSIONS

This study presents a low-cost, noninvasive, direct, and serial oxygen mapping technology to detect spatial differences in wound oxygenation. Clinical use of the films has the potential to monitor wound healing trajectories and guide wound care decisions.

A model for predicting 7-day pressure injury outcomes in paediatric patients: A machine learning approach

AIMS

We sought to explore factors associated with early pressure injury progression and build a model for predicting these outcomes using a machine learning approach.

DESIGN

A retrospective cohort study.

METHODS

In this study, we recruited paediatric patients, with hospital-acquired stage I pressure injury or suspected deep tissue injury, who met the inclusion criteria between 1 January 2015-31 October 2018. We divided patients into two groups, namely healing or delayed healing, then followed them up for 7 days. We analysed patient pressure injury characteristics, demographics, treatment, clinical situation, vital signs, and blood test results, then build prediction models using the Random Forest and eXtreme Gradient Boosting approaches.

RESULTS

The best prediction model, trained and tested using Random Forest with 10 variables, achieved an accuracy, sensitivity, specificity, and area under the curve of 0.82 (SD 0.06), 0.80 (SD 0.08), 0.84 (SD 0.08), and 0.89 (SD 0.06), respectively. The most contributing variables, in order of importance, included serum creatinine, red blood cell, and haematocrit.

CONCLUSION

An awareness of specific conditions and areas that could lead to delayed healing pressure injury in paediatric patients is needed.

IMPACT

This evidence-based prediction model, coupled with the aforementioned clinical indicators, is expected to enhance early prediction of outcomes in paediatric patients thereby improve the quality of care and the outcome of children with PIs.

Specialised wound care clinics in Spain: distribution and characteristics

OBJECTIVE

To determine the number of specialised wound care units/clinics (SWCUs) in Spain, at present, and to describe their most important characteristics.

METHOD

This was an observational study with a descriptive-analytical, cross-sectional, multicentre approach, where the studied population consisted of SWCUs in Spain. A specific data-collection questionnaire was designed using a modified Delphi method, consisting of four rounds, with the collaboration of 10 wound experts. The final questionnaire included 49 items distributed across four dimensions/areas with a content validity index (CVI-Total for pertinence=0.96 and CVI-Total for relevance=0.94.

RESULTS

A total of 42 SWCUs were included in the study. Most SWCUs were based in hospitals (n=15, 35.7%) or healthcare centres, covering a specific healthcare area (n=17, 40.5%). SWCU coordinators were primarily nurses (n=33, 78.6%). Staff members' professions in SWCUs included registered nurses (n=38 units, 92.7%), nursing assistants (n=8 units, 19.5%), podiatrists (n=8 units, 19.5%), vascular surgeons (n=7 units, 17%), osteopaths (n=2 units, 4.8%) and medical doctors from different specialties (n=3 units, 7.2%). For wound aetiology, the most prevalent wounds managed were diabetic foot ulcers (n=38 units, 90.5%), followed by venous leg ulcers (n=36 units, 85.7%) and arterial ischaemic ulcers (n=36 units, 85.7%). A statistically significant association was found between the number of staff members in a SWCU and the existence of resistance/opposition barriers when developing a SWCU (Chi-square test, p=0.049; Cramér's V=0.34; 34%), as well as between resistance/opposition barriers when developing a SWCU and a nurse as coordinator of a SWCU (MacNemar test, p=0.007, Cramér's V=0.35; 35%).

CONCLUSION

The typical SWCU implemented in Spain is located in a hospital or integrated in a healthcare structure that offers coverage to a whole health area and providing services for people with hard-to-heal wounds (wound management and prevention) and health professionals (advice, consultancy and training/education). Despite the growing number of SWCUs in Spain, the future of this new organisational model is uncertain, as there can be barriers to creating them and some deficiencies, such as low staff numbers, which need to be addressed.

Resting TcPO2 levels decrease during liner wear in persons with a transtibial amputation

Background

In our clinic, a substantial number of patients present with transtibial residual limb pain of no specific somatic origin. Silicone liner induced tissue compression may reduce blood flow, possibly causing residual limb pain. Thus, as a first step we investigated if the liner itself has an effect on transcutaneous oxygen pressure (TcPO2).

Methods

Persons with unilateral transtibial amputation and residual limb pain of unknown origin were included. Medical history, including residual limb pain, was recorded, and the SF-36 administered. Resting TcPO2 levels were measured in the supine position and without a liner at 0, 10, 20 and 30 minutes using two sensors: one placed in the Transverse plane over the tip of the Tibia End (= TTE), the other placed in the Sagittal plane, distally over the Peroneal Compartment (= SPC). Measurements were repeated with specially prepared liners avoiding additional pressure due to sensor placement. Statistical analyses were performed using SPSS.

Results

Twenty persons (9 women, 11 men) with a mean age of 68.65 years (range 47–86 years) participated. The transtibial amputation occurred on average 43 months prior to study entry (range 3–119 months). With liner wear, both sensors measured TcPO2 levels that were significantly lower than those measured without a liner (TTE: p < 0.001; SPC: p = 0.002) after 10, 20 and 30 minutes. No significant differences were found between TcPO2 levels over time between the sensors. There were no significant associations between TcPO2 levels and pain, smoking status, age, duration of daily liner use, mobility level, and revision history.

Conclusion

Resting TcPO2 levels decreased significantly while wearing a liner alone, without a prosthetic socket. Further studies are required to investigate the effect of liner wear on exercise TcPO2 levels.

Use of perfusional CBCT imaging for intraprocedural evaluation of endovascular treatment in patients with diabetic foot: a concept paper

Diabetes mellitus (DM) is one of the most common metabolic diseases worldwide; its global burden has increased rapidly over the past decade, enough to be considered a public health emergency in many countries. Diabetic foot disease and, particularly diabetic foot ulceration, is the major complication of DM: through a skin damage of the foot, with a loss of epithelial tissue, it can deepen to muscles and bones and lead to the amputation of the lower limbs. Peripheral arterial disease (PAD) in patients with diabetes, manifests like a diffuse macroangiopathic multi-segmental involvement of the lower limb vessels, also connected to a damage of collateral circulation; it may also display characteristic microaneurysms and tortuosity in distal arteries. As validation method, Bold-MRI is used. The diabetic foot should be handled with a multidisciplinary team approach, as its management requires systemic and localized treatments, pain control, monitoring of cardiovascular risk factors and other comorbidities. CBCT is an emerging medical imaging technique with the original feature of divergent radiation, forming a cone, in contrast with the spiral slicing of conventional CT, and has become increasingly important in treatment planning and diagnosis: from small anatomical areas, such as implantology, to the world of interventional radiology, with a wide range of applications: as guidance for biopsies or ablation treatments. The aim of this project is to evaluate the usefulness of perfusion CBCT imaging, obtained during endovascular revascularization, for intraprocedural evaluation of endovascular treatment in patients with diabetic foot. (www.actabiomedica.it).

Evaluation of time courses of agreement between minutely obtained transcutaneous blood gas data and the gold standard arterial data from spontaneously breathing Asian adults, and various subgroup analyses

BACKGROUND

Usual clinical practice for arterial blood gas analysis (BGA) in conscious patients involves a one-time arterial puncture to be performed after a resting period of 20-30 min. The aim of this study was to evaluate the use of transcutaneous BGA for estimating this gold standard arterial BGA.

METHODS

Spontaneously breathing Asian adults (healthy volunteers and respiratory patients) were enrolled (n = 295). Transcutaneous PO₂ (PtcO₂) and PCO₂ (PtcCO₂) were monitored using a transcutaneous monitor (TCM4, Radiometer Medical AsP, Denmark) with sensors placed on the chest, forearm, earlobe or forehead. Transcutaneous BGA at 1-min intervals was compared with arterial BGA at 30 min. Reasonable steps to find severe hypercapnia with PaCO₂ > 50 mmHg were evaluated.

RESULTS

Sensors on the chest and forearm were equally preferred and used because of small biases (n = 272). The average PCO₂ bias was close to 0 mmHg at 4 min, and was almost constant (4-5 mmHg) with PtcCO₂ being higher than PaCO₂ at ≥8 min. The limit of agreement for PCO₂ narrowed over time: ± 13.6 mmHg at 4 min, ± 7.5 mmHg at 12-13 min, and ± 6.3 mmHg at 30 min. The limit of agreement for PO₂ also narrowed over time (± 23.1 mmHg at 30 min). Subgroup analyses showed that the PaCO₂ and PaO₂ levels, gender, and younger age significantly affected the biases. All hypercapnia subjects with PaCO₂ > 50 mmHg (n = 13) showed PtcCO₂ ≥ 50 mmHg for until 12 min.

CONCLUSIONS

Although PtcCO₂ is useful, it cannot completely replace PaCO₂ because PCO₂ occasionally showed large bias. On the other hand, the prediction of PaO₂ using PtcO₂ was unrealistic in Asian adults. PtcCO₂ ≥ 50 mmHg for until 12 min can be used as a screening tool for severe hypercapnia with PaCO₂ > 50 mmHg.

Foot Salvage with Selective Arterialization of Pedal Venosomes

Background

Lower extremity salvage using microvascular flaps can be considered in high-functioning patients, but indications for salvage are often restricted by distal microvascular disease that may threaten the foot as a whole. Selective arterialization of specific pedal venosomes is a novel potential solution to this problem.

Methods

A 48-year-old man with a chronic left plantar forefoot wound, osteomyelitis of the second and third metatarsal heads, and critical limb ischemia was evaluated for foot salvage. Despite a patent popliteal to posterior tibial bypass graft, residual ischemia was present in the first and second toes due to severe microvascular disease. This wound was reconstructed with a free partial medial rectus abdominis flow-through flap based on the medial branch of the deep inferior epigastric artery. The lateral branch was used as a flow-through vessel to arterialize the dorsal veins of the first webspace.

Results

Arterialization of the first webspace veins resulted in an immediate intraoperative improvement of the color of the first and second toes, along with creation of an arterial Doppler signal. The flap effectively covered the wound. The patient went on to heal completely and return to unrestricted ambulation. Transcutaneous oxygen measurement values of the dorsal foot improved from 35.8 mm Hg preoperatively to 48.3 mm Hg postoperatively.

Conclusions

In patients with focal areas of critical ischemia, selective arterialization of the venous system may be an effective method of preventing tissue loss and improving wound healing. A flow-through flap can be used to accomplish this in tandem with wound reconstruction.

2D perfusion-angiography during endovascular intervention for critical limb threatening ischemia - A feasibility study

Purpose

Two-dimensional perfusion angiography is a new method to quantify and evaluate tissue perfusion during endovascular intervention. The aim was to evaluate time-patterns and dynamics of contrast arrival and distribution before and after endovascular intervention in patients with critical limb threatening ischemia.

Methods

Data were collected from 37 patients with critical limb threatening ischemia due to infra-inguinal occlusive disease having a successful endovascular procedure. two-dimensional perfusion angiography was used as a post-processing software with analysis of numeric parameters related to arrival and distribution patterns of contrast.

Results

Thirty-three patients were successfully analysed whereas four patients were excluded due to motion artefacts. All patients were successfully treated with recanalization of the superficial femoral, popliteal, below the knee-vessels or a combination. Short-term improvement at 30-day follow-up was noted both clinically and by ankle-brachial index and toe pressure measurements. A significant reduction in contrast arrival time between pre-and post-angioplasty runs was noted as measured by arrival time median 3.2 and interquartile range (2.5–4.2) vs. 2.6 (1.6–3.4) and time-to-peak 4.1 (3.6–5.0) vs. 3.1 (2.3–3.9) p = 0.009. An increased wash-in rate was also observed 18.3 (12.6–21) vs. 30.1 (22–30.5) p = 0.001 between pre-and post-angioplasty runs.

Conclusions

The use of perfusion angiography for evaluation of foot-circulation during endovascular interventions provides new information regarding quantitative assessment of contrast inflow before and after endovascular intervention without the need for extra contrast or runs. No selective catheterisation is necessary. The technique is easily adopted in a clinical setting. Further studies are necessary to create robust clinical endpoints.

Cost-effectiveness of adjunct haemoglobin spray in the treatment of hard-to-heal wounds in a UK NHS primary care setting

OBJECTIVE

To evaluate the cost-effectiveness of topical haemoglobin spray as adjunct therapy in the treatment of hard-to-heal wounds within a UK National Health Service (NHS) community setting.

METHOD

In a previously published comparative clinical evaluation, 50 consecutive patients treated with topical haemoglobin spray, as adjunct to standard care and followed up over 26 weeks, were compared with 50 consecutive retrospective controls from the same clinic treated with the same standard care protocol in the year prior to the introduction of adjunct topical haemoglobin spray. A de novo cost-effectiveness and break-even analysis were performed, using data from the previously published clinical evaluation, for all patients (intent-to-treat) and for patients with complete follow-up using a micro-costing approach and considering only wound care dressing costs.

RESULTS

At 26 weeks, the total cost of dressings for all patients in the intervention group was £6953 with 874 cumulative weeks healed, compared with £9547 with 278 cumulative weeks healed for all patients in the control group. The incremental cost-effectiveness ratio (ICER), the incremental cost per additional week healed with adjunct topical haemoglobin spray, is therefore negative (dominant). Total treatment costs per week were lower from week six onwards, with break-even estimated to be at week 10.2. When considering only patients with complete follow-up, the results were similarly dominant, with a mean 10.9 more weeks healed, a mean dressing cost saving per patient of £81.83 by week 26 (-37%). Cost savings were realised from week five, and a break-even was estimated to occur at week 8.0.

CONCLUSION

Topical haemoglobin spray has the potential to restore the healing process, reduce healing times and reduce dressing costs in a NHS community setting, within a few weeks of adoption.

A New Modified Surgical Technique of In Situ Reverse Arterialization: Leaving the Distal Saphenous Side Branches Open of Nonreconstructable Ischemic Leg Leads to Full Recovery

BACKGROUND

Arterialization of the foot veins in patients with ischemic foot usually result in excessive foot edema, wound infection, venous gangrene, long hospitalization duration, and a high rate of amputation. We herein present an improved method of foot revascularization via the superficial venous system by in situ reverse arterialization (ISRA) of the foot venous bed, leaving the distal saphenous side branches open.

METHODS

A 69-year-old patient with toe wet gangrene and end-stage peripheral vascular disease with absence of foot target arteries underwent ISRA procedure, using the great saphenous vein, which was anastomosed end-to-side to the proximal superficial femoral artery. Only proximal saphenous tributaries were ligated until arterial flow reached the pedal superficial veins.

RESULTS

Postoperatively, the foot regained normal pulsation over the superficial venous system. The patient did not experience foot edema. On-table subtraction angiography demonstrated arterial flow through the long saphenous and dorsal foot veins, with returned venous flow through the anterior and posterior tibial veins. Methoxyisobutylisonitrile scan conducted 4 weeks postoperatively demonstrated positive oxygen uptake of the pedal muscles, which was absent before surgery. Electron microscopy of the muscles at the level of the transmetatarsal amputation demonstrated regeneration of muscle tissue with mitosis 6 weeks postoperatively. During 1,000 days of follow-up postsurgery, the flow was reduced and the transcutaneous pO₂ level of the foot increased up to 76 mm Hg.

CONCLUSIONS

This new modified surgical technique of ISRA, in which only proximal saphenous tributaries were ligated in order to prevent high systemic pressure in the foot venous low pressure system, resulted in increased levels of transcutaneous pO₂ and reduced flow, leading to full recovery of the ischemic foot.

Applicability of Transcutaneous Oxygen Tension Measurement in the Assessment of Chronic Limb-Threatening Ischemia

Transcutaneous oxygen tension measurement (TcPO₂) is widely applied for the evaluation of chronic limb-threatening ischemia (CLTI). Nevertheless, studies that focused on the clinical value of TcPO₂ have shown varying results. We identified factors that potentially play a role in TcPO₂ measurement variation such as probe placement, probe temperature, and the use of a reference probe. In this review of the current literature, we assessed the application of these factors. A systematic search was conducted. Parameters that were assessed were probe placement, probe temperature, and mentioning and/or use of a reference probe. In total, 36 articles were eligible for analysis. In 24 (67%) studies, probes were placed on specific anatomical locations. Seven (19%) studies placed probes, regardless of the location of the ulcer, adjacent to an ischemic lesion or ulcer (perilesion). Selected temperature setting of the probe differed; in 18 (50%), a default probe temperature of 44°C was selected, and in 13 (36%), a different temperature was selected. In 31 (84%) studies, the use of a reference probe was not reported. Transcutaneous oxygen tension measurement is applied diversely in patients with CLTI. Homogeneity in TcPO₂ protocols is warranted for reliable clinical application and to compare future TcPO₂ research.

Naturally-derived electrospun wound dressings for target delivery of bio-active agents

Electrospun nanofibers are known as the advanced means for wound dressing. They have represented remarkable potency to encapsulate and deliver biomolecules promoting the wound healing process. Compared to synthetic polymers, naturally derived polymers (NDP) are more qualified candidates for fabrication of biomedical electrospun scaffolds. Not only nanofibers of NDP illustrate higher biocompatibility and biodegradability rates, but also they mimic the native extracellular matrix more closely, which leads to the wound closure acceleration by enhancing tissue regeneration. Aside, incorporation of bioactive molecules and therapeutic agents into the nanofibers can generate innovative bioactive wound dressings with significantly improved healing potentials. This paper starts with a brief discussion on the steps and factors influencing the wound healing process. Then, the recent applications of electrospun nanofibers as wound dressing with healing accelerating properties are reviewed. Further, the various healing agents and alternative strategies for modification and functionalization of bioactive naturally-derived electrospun nanofibers are discussed.

Transcutaneous oxygen pressure (TcPO2) and ulcer outcome in diabetic patients: Is there any correlation?

BACKGROUND

Due to poor blood circulation, the prevalence of foot ulcer is extensively reported among diabetic patients. Diabetic neuropathy is the critical factor of diabetes that can affect the nerves.

OBJECTIVE

To examine the outcomes and correlation between TcPO2 and ulcer outcomes among diabetic patients.

MATERIAL AND METHODS

A prospective cohort design has been employed to compare and correlate TcPO2 group with ulcer outcomes. A total of 192 patients were enrolled, who underwent diagnosis for ulcer outcome. Descriptive analysis and Pearson Correlation were used for data analysis via SPSS version 20.

RESULTS

The prevalence of minor amputation among diabetic patients in 25-40 mmHg 75 (85.22%) and >40 mmhG 73 (84.88%) group is reported for ulcer outcome. Mostly diabetic patients were healed with intact skin (male = 36, female = 73), and improved ulcer healing (male = 23, female = 43). Correlation between ulcer size (p = .016), ABI (p = .044), TBI (p = .000), Adiponectin (p = .009), HbA1c (p = .033), and S. creatinine (p = .025) was significant with TcpO2 group.

CONCLUSIONS

The study concluded that there is a positive and significant correlation between TcPO2 group and ulcer outcome. There is a positive association between TcPO2 baseline and degree of ulcer healing with intact skin.

Predictors of responders to mononuclear stem cell-based therapeutic angiogenesis for no-option critical limb ischemia

Background

Although the mononuclear cell (MNC) transplantation could theoretically induce therapeutic angiogenesis in the patients with no-option critical limb ischemia (NO-CLI), the clinical responses to this approach are inconsistent among different clinical trials. The purpose of this study was to identify the prognostic factors of responders and develop a predictive nomogram to guide patient selection.

Methods

We retrospectively reviewed a consecutive NO-CLI cohort who received peripheral blood-derived transplantation in our center. The patients who survived and achieved complete remission of CLI at 6 months post-transplantation were defined as responders. Logistic regression models were used to screen and identify the prognostic factors based on which predictive nomogram was developed. A receiver operating characteristic (ROC) curve and a calibration curve were drawn to determine the discrimination level and predictive accuracy.

Results

The study ultimately enrolled 103 patients, including 58 responders and 45 non-responders. Based on the multivariate regression analysis, age ≥ 50 years (odds ratio [OR] 0.201, P = 0.004), blood fibrinogen > 4 g/L (OR 0.176, P = 0.003), arterial occlusion above the knee/elbow (OR 0.232, P = 0.010), the transcutaneous pressure of oxygen (TcPO₂) (OR 1.062, P = 0.006), and the Log total transplanted CD34⁺ cell count (OR 3.506, P = 0.046) were identified as independent prognostic factors of the responders in the nomogram. An area under the ROC curve of 0.851 indicated good discrimination, and the calibration curve of the predicted probability showed optimal agreement with that of the observed probability.

Conclusions

Age, blood fibrinogen, arterial occlusion level, TcPO₂, and the total transplanted CD34⁺ cell count were independent prognostic factors of the responders. A nomogram with high discrimination and accuracy was developed to provide individualized predictions.

Trail registration

ChiCTR, ChiCTR1800019401. Registered 9 November 2018—Retrospectively registered

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1117-5) contains supplementary material, which is available to authorized users.

Matrix composition in 3-D collagenous bioscaffolds modulates the survival and angiogenic phenotype of human chronic wound dermal fibroblasts

There is a substantial need for new strategies to stimulate cutaneous tissue repair in the treatment of chronic wounds. To address this challenge, our team is developing modular biomaterials termed "bead foams", comprised of porous beads synthesized exclusively of extracellular matrix (ECM) and assembled into a cohesive three-dimensional (3-D) network. In the current study, bead foams were fabricated from human decellularized adipose tissue (DAT) or commercially-sourced bovine tendon collagen (COL) to explore the effects of ECM composition on human wound edge dermal fibroblasts (weDF) sourced from chronic wound tissues. The DAT and COL bead foams were shown to be structurally similar, but compositionally distinct, containing different levels of glycosaminoglycan content and collagen types IV, V, and VI. In vitro testing under conditions simulating stresses within the chronic wound microenvironment indicated that weDF survival and angiogenic marker expression were significantly enhanced in the DAT bead foams as compared to the COL bead foams. These findings were corroborated through in vivo assessment in a subcutaneous athymic mouse model. Taken together, the results demonstrate that weDF survival and paracrine function can be modulated by the matrix source applied in the design of ECM-derived scaffolds and that the DAT bead foams hold promise as cell-instructive biological wound dressings. STATEMENT OF SIGNIFICANCE: Biological wound dressings derived from the extracellular matrix (ECM) can be designed to promote the establishment of a more permissive microenvironment for healing in the treatment of chronic wounds. In the current work, we developed modular biomaterials comprised of fused networks of porous ECM-derived beads fabricated from human decellularized adipose tissue (DAT) or commercially-available bovine collagen. The bioscaffolds were designed to be structurally similar to provide a platform for investigating the effects of ECM composition on human dermal fibroblasts isolated from chronic wounds. Testing in in vitro and in vivo models demonstrated that cell survival and pro-angiogenic function were enhanced in the adipose-derived bioscaffolds, which contained higher levels of glycosaminoglycans and collagen types IV, V, and VI. Our findings support that the complex matrix composition within DAT can induce a more pro-regenerative cellular response for applications in wound healing.

Hypoxia arising from concerted oxygen consumption by neutrophils and microorganisms in biofilms

Infections associated with microbial biofilms are often found to involve hypoxic or anoxic conditions within the biofilm or its vicinity. To shed light on the phenomenon of local oxygen depletion, mathematical reaction-diffusion models were derived that integrated the two principal oxygen sinks, microbial respiration and neutrophil consumption. Three simple one-dimensional problems were analyzed approximating biofilm near an air interface as in a dermal wound or mucus layer, biofilm on an implanted medical device, or biofilm aggregates dispersed in mucus or tissue. In all three geometries considered, hypoxia at the biofilm-neutrophil interface or within the biofilm was predicted for a subset of plausible parameter values. The finding that oxygen concentration at the biofilm-neutrophil juncture can be diminished to hypoxic levels is biologically relevant because oxygen depletion will reduce neutrophil killing ability. The finding that hypoxia can readily establish in the interior of the biofilm is biologically relevant because this change will alter microbial metabolism and persistence.

Topical oxygen therapy stimulates healing in difficult, chronic wounds: a tertiary centre experience

OBJECTIVE

Oxygen plays a central role in wound healing. Recent technological advances have miniaturised oxygen delivery systems, with novel topical oxygen therapy allowing patients to receive oxygen therapy 24 hours a day while remaining completely mobile. Here we aim to examine the efficacy and safety of continuous topical oxygen diffusion in a 'real-world' setting.

METHODS

Topical oxygen therapy (TOT) was evaluated in patients with chronic, non-healing wounds in a tertiary referral specialist clinic.

RESULTS

The mean wound duration before TOT was 15 months. Regardless of treatment duration, in this previously non-healing group complete wound closure was observed in 32% of the total patients treated with the TOT device. However, optimal wound healing occurred when the device was used for >25 days, with an 83% wound area reduction and 47% wound closure rate seen in venous leg ulcers (VLUs) and a 74% reduction and a 57% wound closure rate in arterial foot ulcers.

CONCLUSION

Use of TOT in chronic wounds stimulates a healing state. In our study, almost half of the previously non-healing wounds closed.

Smart Bandages: The Future of Wound Care

Chronic non-healing wounds are major healthcare challenges that affect a noticeable number of people; they exert a severe financial burden and are the leading cause of limb amputation. Although chronic wounds are locked in a persisting inflamed state, they are dynamic and proper therapy requires identifying abnormalities, administering proper drugs and growth factors, and modulating the conditions of the environment. In this review article, we discuss technologies that have been developed to actively monitor the wound environment. We also highlight drug delivery tools that have been integrated with bandages to facilitate precise temporal and spatial control over drug release and review automated or semi-automated systems that can respond to the wound environment.

Transcutaneous oximetry: variability in normal values for the upper and lower limb

INTRODUCTION

Published normal transcutaneous oxygen partial pressures (P_tcO₂) for the chest and lower limb have defined tissue hypoxia as a value of < 40 mmHg (< 30 mmHg in some patients, < 50 mmHg in others).

AIM

To determine 'normal' P_tcO₂ for the upper and lower limb in healthy, non-smoking adults using the Radiometer® TCM400 with tc Sensor E5250.

METHOD

Thirty-two volunteers had transcutaneous oxygen measurements (TCOM) performed on the chest, upper and lower limbs breathing air, with leg then arm elevated and whilst breathing 100% oxygen.

RESULTS

Room-air P_tcO₂ (mmHg, mean (95% confidence interval)) were: chest: 53.6 (48.7-58.5); upper arm: 60.0 (56.1-64.0); forearm: 52.3 (44.8-55.8); dorsum of hand: 50.2 (46.1-54.3); thenar eminence: 70.8 (67.7-73.8); hypothenar eminence: 77.9 (75.1-80.7); lateral leg: 50.2 (46.2-54.2); lateral malleolus: 50.5 (46.6-54.3); medial malleolus: 48.9 (45.6-52.1); dorsum, between first and second toe: 53.1 (49.2-57.0); dorsum, proximal to fifth toe: 58.5 (55.0 - -62.0); plantar, 1st MTP: 73.7 (70.3-77.1). Nineteen subjects had at least one room-air P_tcO₂ below 40 mmHg (nine upper limb, 13 lower limb, four chest). Approximately 10% lower limb P_tcO₂ were < 100 mmHg on normobaric oxygen. Only one subject at one site had an upper limb P_tcO₂ < 100 mmHg breathing oxygen.

CONCLUSION

The broad dispersion in P_tcO₂ in our healthy cohort reflects the inherent biologic variability in dermal perfusion and oxygen delivery, making it difficult to define narrow, rigid 'normal' values. Thus, we cannot recommend a single P_tcO₂ value as 'normal' for the upper or lower limb. A thorough patient assessment is essential to establish appropriateness for hyperbaric oxygen therapy, with TCOM used as an aid to guide this decision and not as an absolute.

Critical Limb Ischemia: A Practical Up-To-Date Review

Critical limb ischemia (CLI) is the most advanced form of peripheral artery disease. It is associated with significant morbidity and mortality and high management costs. It carries a high risk of amputation and local infection. Moreover, cardiovascular complications remain a major concern. Although it is a well-known entity and new technological and therapeutic advances have been made, this condition remains poorly addressed, with significantly heterogeneous management, especially in nonexperienced centers. This review, from a third-level dedicated inpatient and outpatient cardioangiology structure, aims to provide an updated summary on the topic of CLI of its complexity, encompassing epidemiological, social, economical and, in particular, diagnostic/imaging issues, together with potential therapeutic strategies (medical, endovascular, and surgical), including the evaluation of cardiovascular risk factors, the diagnosis, and treatment together with prognostic stratification.

Below-Knee Amputation Failure and Poor Functional Outcomes Are Higher Than Predicted in Contemporary Practice

OBJECTIVE

The perceived functional benefit of below-knee amputation (BKA) must be carefully weighed against the need for potential reinterventions. This study sought to examine the contemporary clinical and functional outcomes of patients undergoing BKA in the endovascular era.

METHODS

All patients who underwent BKA from January 2008 to December 2014 at a single tertiary medical center were retrospectively reviewed. Demographics, comorbidities, ambulation status, and transcutaneous oximetry (TcPO2) values were recorded. Study end points included freedom from conversion to above-knee amputation (AKA), freedom from conversion to AKA or death, BKA healing, and ambulation. Statistical modeling was performed to determine associations with BKA failure.

RESULTS

Over the study interval, 130 limbs underwent BKA in 120 patients. Transcutaneous oximetry studies were obtained in 65% (n = 85). Thirty-eight percent (n = 46) of all BKA patients went on to heal and ambulate. Twenty-five percent (n = 33) required reintervention, 24 with conversion to AKA, and 9 with BKA revision. One-year freedom from conversion to AKA was 76% and was decreased among those with lower TcPO2 levels (60% TcPO2 <40 vs 81% TcPO2 ≥40; P = .04). One-year composite freedom from conversion to AKA/death was 60% and was decreased among those with lower TcPO2 readings (39% TcPO2 <40 vs 69% TcPO2 ≥40; P = .01).

CONCLUSION

Despite a perceived functional bias toward knee salvage at the time of major amputation, most patients failed to postoperatively ambulate. Those with decreased TcPO2 levels (<40 mm Hg) have a 2-fold higher risk of AKA conversion or death, while nearly one-fourth of all BKA patients will succumb to the same fate irrespective of TcPO2. This suggests that many BKA patients in the endovascular era fail to derive the perceived benefit of knee salvage at the time of their index amputation. These findings highlight the need for careful patient selection and for a shared decision-making model in this frail population.

Microsensor and transcriptomic signatures of oxygen depletion in biofilms associated with chronic wounds

Biofilms have been implicated in delayed wound healing, although the mechanisms by which biofilms impair wound healing are poorly understood. Many species of bacteria produce exotoxins and exoenzymes that may inhibit healing. In addition, oxygen consumption by biofilms and by the responding leukocytes, may impede wound healing by depleting the oxygen that is required for healing. In this study, oxygen microsensors to measure oxygen transects through in vitro cultured biofilms, biofilms formed in vivo within scabs from a diabetic (db/db) mouse wound model, and ex vivo human chronic wound specimens was used. The results showed that oxygen levels within mouse scabs had steep gradients that reached minima ranging from 17 to 72 mmHg on live mice and from 6.4 to 1.1 mmHg on euthanized mice. The oxygen gradients in the mouse scabs were similar to those observed for clinical isolates cultured in vitro and for human ex vivo specimens. To characterize the metabolic activities of the bacteria in the mouse scabs, transcriptomics analyses of Pseudomonas aeruginosa biofilms associated with the db/db mice wounds was performed. The results demonstrated that the bacteria expressed genes for metabolic activities associated with cell growth. Interestingly, the transcriptome results also indicated that the bacteria within the wounds experienced oxygen-limitation stress. Among the bacterial genes that were expressed in vivo were genes associated with the Anr-mediated hypoxia-stress response. Other bacterial stress response genes highly expressed in vivo were genes associated with stationary-phase growth, osmotic stress, and RpoH-mediated heat shock stress. Overall, the results supported the hypothesis that bacterial biofilms in chronic wounds promote chronicity by contributing to the maintenance of localized low oxygen tensions, through their metabolic activities and through their recruitment of cells that consume oxygen for host defensive processes.

Conservative Treatment in Selected Patients with Severe Critical Limb Ischemia

OBJECTIVE

To assess the outcome of conservative treatment of severe critical limb ischemia (CLI) classified as Rutherford 5/6.

BACKGROUND

The preferred therapy for CLI is either endovascular revascularization or bypass surgery. With a growing aged population with more serious comorbidities, these therapies are not always a viable option. Primary amputation leads to decreased mobility and a reduced quality of life. There is a lack of literature regarding the outcome of conservative therapy.

METHODS

Hospital charts were reviewed of all patients who were diagnosed with Rutherford classification 5-6 and received conservative treatment and lacked interventional options. Outcome measures were mortality, complete wound closure, and limb salvage rate.

RESULTS

38 patients were included with a median age of 80 years (range 57-97). The amputation rate during follow-up was 16%. In 58% of patients, complete wound closure was achieved. All-cause mortality was 58% with a 2-year survivability rate of 55%.

CONCLUSIONS

Conservative management in our selected patients with CLI results in a moderate rate of wound closure and acceptable amputation rates albeit with a high mortality rate. For patients not eligible for endovascular revascularization or bypass surgery, conservative treatment could be a viable option besides primary limb amputation.

Assessment of foot perfusion in patients with a diabetic foot ulcer

Assessment of foot perfusion is a vital step in the management of patients with diabetic foot ulceration, in order to understand the risk of amputation and likelihood of wound healing. Underlying peripheral artery disease is a common finding in patients with foot ulceration and is associated with poor outcomes. Assessment of foot perfusion should therefore focus on identifying the presence of peripheral artery disease and to subsequently estimate the effect this may have on wound healing. Assessment of perfusion can be difficult because of the often complex, diffuse and distal nature of peripheral artery disease in patients with diabetes, as well as poor collateralisation and heavy vascular calcification. Conventional methods of assessing tissue perfusion in the peripheral circulation may be unreliable in patients with diabetes, and it may therefore be difficult to determine the extent to which poor perfusion contributes to foot ulceration. Anatomical data obtained on cross-sectional imaging is important but must be combined with measurements of tissue perfusion (such as transcutaneous oxygen tension) in order to understand the global and regional perfusion deficit present in a patient with diabetic foot ulceration. Ankle-brachial pressure index is routinely used to screen for peripheral artery disease, but its use in patients with diabetes is limited in the presence of neuropathy and medial arterial calcification. Toe pressure index may be more useful because of the relative sparing of pedal arteries from medial calcification but may not always be possible in patients with ulceration. Fluorescence angiography is a non-invasive technique that can provide rapid quantitative information about regional tissue perfusion; capillaroscopy, iontophoresis and hyperspectral imaging may also be useful in assessing physiological perfusion but are not widely available. There may be a future role for specialized perfusion imaging of these patients, including magnetic resonance imaging techniques, single-photon emission computed tomography and PET-based molecular imaging; however, these novel techniques require further validation and are unlikely to become standard practice in the near future.

What's new in the literature: an update of new research since the original WHS diabetic foot ulcer guidelines in 2006

The objective of the paper was to update the diabetic foot ulcer guidelines that were previously published in 2006. We performed a key word search using MEDLINE and Cochrane reviews for publication between January 2006 and January 2012. Articles that fit the inclusion criteria were reviewed and the previous guidelines were updated.

Peripheral arterial disease and revascularization of the diabetic foot

Diabetes is a complex disease with many serious potential sequelae, including large vessel arterial disease and microvascular dysfunction. Peripheral arterial disease is a common large vessel complication of diabetes, implicated in the development of tissue loss in up to half of patients with diabetic foot ulceration. In addition to peripheral arterial disease, functional changes in the microcirculation also contribute to the development of a diabetic foot ulcer, along with other factors such as infection, oedema and abnormal biomechanical loading. Peripheral arterial disease typically affects the distal vessels, resulting in multi-level occlusions and diffuse disease, which often necessitates challenging distal revascularisation surgery or angioplasty in order to improve blood flow. However, technically successful revascularisation does not always result in wound healing. The confounding effects of microvascular dysfunction must be recognised--treatment of a patient with a diabetic foot ulcer and peripheral arterial disease should address this complex interplay of pathophysiological changes. In the case of non-revascularisable peripheral arterial disease or poor response to conventional treatment, alternative approaches such as cell-based treatment, hyperbaric oxygen therapy and the use of vasodilators may appear attractive, however more robust evidence is required to justify these novel approaches.

Great toe necrosis predicts an unfavorable limb salvage prognosis

Summary:

The initial location of necrosis may affect the limb salvage rate. This study of 130 patients with chronic toe ulcers or gangrene was performed to assess whether the location of initial necrosis in the toes affected limb salvage prognosis. The patients were divided into 2 groups according to whether the initial necrosis was in the great toe or in other toes. Limb salvage prognosis was determined retrospectively. In the great toe group, the rates of total toe loss and major amputation were 50.0% and 24.4%, respectively. When the initial necrosis was in other toes, these rates were 27.3% and 9.3%, respectively. Great toe necrosis is associated with significantly higher rates of total toe loss (odds ratio = 3.10; P = 0.003; 95% confidence interval, 1.43−6.68) and major amputation (odds ratio = 3.66; P = 0.007; 95% confidence interval, 1.37−9.79). The great toe is supplied by 3 source arteries, whereas the lesser toes are fed by 1 or 2 arteries. Therefore, necrosis initiating from the great toe may reflect the presence of severe vascular disorders. The great toe is also anatomically connected to much of the foot via the tendons. Infection is more likely to spread along these tendons, which may reduce limb prognosis. Thus, the initial location of necrosis may be predictive of limb prognosis.

Non-invasive transdermal two-dimensional mapping of cutaneous oxygenation with a rapid-drying liquid bandage

Oxygen plays an important role in wound healing, as it is essential to biological functions such as cell proliferation, immune responses and collagen synthesis. Poor oxygenation is directly associated with the development of chronic ischemic wounds, which affect more than 6 million people each year in the United States alone at an estimated cost of $25 billion. Knowledge of oxygenation status is also important in the management of burns and skin grafts, as well as in a wide range of skin conditions. Despite the importance of the clinical determination of tissue oxygenation, there is a lack of rapid, user-friendly and quantitative diagnostic tools that allow for non-disruptive, continuous monitoring of oxygen content across large areas of skin and wounds to guide care and therapeutic decisions. In this work, we describe a sensitive, colorimetric, oxygen-sensing paint-on bandage for two-dimensional mapping of tissue oxygenation in skin, burns, and skin grafts. By embedding both an oxygen-sensing porphyrin-dendrimer phosphor and a reference dye in a liquid bandage matrix, we have created a liquid bandage that can be painted onto the skin surface and dries into a thin film that adheres tightly to the skin or wound topology. When captured by a camera-based imaging device, the oxygen-dependent phosphorescence emission of the bandage can be used to quantify and map both the pO2 and oxygen consumption of the underlying tissue. In this proof-of-principle study, we first demonstrate our system on a rat ischemic limb model to show its capabilities in sensing tissue ischemia. It is then tested on both ex vivo and in vivo porcine burn models to monitor the progression of burn injuries. Lastly, the bandage is applied to an in vivo porcine graft model for monitoring the integration of full- and partial-thickness skin grafts.

Sulodexide as Adjunctive Therapy in Diabetic Foot Patients With Critical Limb Ischemia Treated With Percutaneous Transluminal Angioplasty

We evaluated the safety and efficacy of sulodexide, a biocompound of glycosamin-glicans, as adjunct medical therapy to percutaneous transluminal angioplasty (PTA) in diabetes mellitus (DM) patients with critical limb ischemia (CLI). We studied 27 consecutive DM patients with CLI successfully subjected to PTA who, on top of standard antiplatelet therapy, received sulodexide 25 mg bid, and were followed-up for 24 weeks, monitoring adverse events, transcutaneous oxygen tension (TcPO₂), ankle-brachial pressure index, pain, and ulcer dimension. At the end of follow-up, ulcer healing, amputation rates, and cardiovascular risk profile of patients were evaluated. Patients were compared with a historical superimposable control group that was treated for the same indications in the same way as the study group, except for sulodexide inception. No differences in ulcer healing and amputation rates were found at the end of follow-up between the groups. In the study group, TcPO₂ was significantly (P < .05) higher at the end of follow-up, and pain intensity was reduced more rapidly. Plasma fibrinogen and plasma creatinine concentration were significantly (P < .05) reduced in study group at the end of follow-up. No differences in adverse events were observed between the groups during follow-up. Our data suggest that sulodexide administration after PTA, on top of antiplatelet therapy, may improve the outcome of PTA in DM patients with CLI by improving microcirculatory function.

'Real angiosome' assessment from peripheral tissue perfusion using tissue oxygen saturation foot-mapping in patients with critical limb ischemia

OBJECTIVES

The "tissue oxygen saturation (StO2) foot-mapping" method was developed using a non-invasive near-infrared tissue oximeter monitor to classify the foot regions as ischemic and non-ischemic areas. The purpose of this study was to evaluate StO2 foot-mapping as a reliable method to detect ischemic areas in the feet of patients with critical limb ischemia (CLI), and to compare the results with assessments from the angiosome model.

METHODS

The foot areas of 20 CLI patients and 20 healthy controls were classified into four regions: (1) 0 ≤ StO2 < 30%, (2) 30 ≤ StO2 < 50%, (3) 50 ≤ StO2 < 70%, and (4) 70 ≤ StO2 ≤ 100% to perform StO2 foot-mapping. Each area occupancy rate was compared between the two groups, and the threshold StO2 value for detecting ischemia was set. Next, the locations of ulcers (in 16 patients) were compared to the predicted ischemic regions by the StO2 foot-mapping and by the angiosome model and angiography.

RESULTS

In regions (1) and (2) (StO2 < 50%), the area occupancy rate was significantly higher in the CLI group and almost zero in the control group, so that the threshold StO2 value for detecting ischemia was set at 50%. The locations of ulcers were compatible with StO2 foot-mapping in 87.5% of the cases (14/16), while they were compatible with the assessment from the angiosome model in 68.8% of the cases (11/16).

CONCLUSIONS

This study suggests that StO2 foot-mapping can successfully and non-invasively detect ischemic areas in the peripheral tissue of the foot, and also more appropriately than the assessment provided by the angiosome model. StO2 foot-mapping can be used to evaluate the real angiosome: the real distribution of the peripheral tissue perfusion in the CLI patient's foot, which is determined by the peripheral microvascular blood flow, rather than the main arterial blood flow.

Continuous topical oxygen for the treatment of chronic wounds: a pilot study

Oxygen is essential for all stages of wound healing. Previous research has shown topical administration of oxygen to have positive effects on wound healing. In this study, the application of transdermal continuous topical oxygen therapy (TCOT) was evaluated for its effect on chronic wound healing in 9 patients. After 4 weeks of treatment, mean wound surface area and wound infection checklist scores were significantly reduced. Signs of bacterial damage were also reduced. Findings from this study suggest TCOT may be beneficial in promoting chronic wound healing.