TcPO2 as an accurate predictor of therapy in limb salvage

Current Opinion on Diagnosis of Peripheral Artery Disease in Diabetic Patients

Peripheral arterial disease (PAD) prevalence and diabetes mellitus (DM) prevalence are continuously increasing worldwide. The strong relationship between DM and PAD is highlighted by recent evidence. PAD diagnosis in diabetic patients is very important, particularly in patients with diabetic foot disease (DFD); however, it is often made difficult by the characteristics of such diseases. Diagnosing PAD makes it possible to identify patients at a very high cardiovascular risk who require intensive treatment in terms of risk factor modification and medical therapy. The purpose of this review is to discuss the diagnostic methods that allow for a diagnosis of PAD in diabetic patients. Non-invasive tests that address PAD diagnosis will be discussed, such as the ankle-brachial index (ABI), toe pressure (TP), and transcutaneous oxygen pressure (TcPO2). Furthermore, imaging methods, such as duplex ultrasound (DUS), computed tomography angiography (CTA), magnetic resonance angiography (MRA), and digital subtraction angiography (DSA), are described because they allow for diagnosing the anatomical localization and severity of artery stenosis or occlusion in PAD. Non-invasive tests will also be discussed in terms of their ability to assess foot perfusion. Foot perfusion assessment is crucial in the diagnosis of critical limb ischemia (CLI), the most advanced PAD stage, particularly in DFD patients. The impacts of PAD diagnosis and CLI identification in diabetic patients are clinically relevant to prevent amputation and mortality.

The intersocietal IWGDF, ESVS, SVS guidelines on peripheral artery disease in people with diabetes and a foot ulcer

Diabetes related foot complications have become a major cause of morbidity and are implicated in most major and minor amputations globally. Approximately 50% of people with diabetes and a foot ulcer have peripheral artery disease (PAD) and the presence of PAD significantly increases the risk of adverse limb and cardiovascular events. The International Working Group on the Diabetic Foot (IWGDF) has published evidence based guidelines on the management and prevention of diabetes related foot complications since 1999. This guideline is an update of the 2019 IWGDF guideline on the diagnosis, prognosis and management of peripheral artery disease in people with diabetes mellitus and a foot ulcer. For this guideline the IWGDF, the European Society for Vascular Surgery and the Society for Vascular Surgery decided to collaborate to develop a consistent suite of recommendations relevant to clinicians in all countries. This guideline is based on three new systematic reviews. Using the Grading of Recommendations, Assessment, Development, and Evaluation framework clinically relevant questions were formulated, and the literature was systematically reviewed. After assessing the certainty of the evidence, recommendations were formulated which were weighed against the balance of benefits and harms, patient values, feasibility, acceptability, equity, resources required, and when available, costs. Through this process five recommendations were developed for diagnosing PAD in a person with diabetes, with and without a foot ulcer or gangrene. Five recommendations were developed for prognosis relating to estimating likelihood of healing and amputation outcomes in a person with diabetes and a foot ulcer or gangrene. Fifteen recommendations were developed related to PAD treatment encompassing prioritisation of people for revascularisation, the choice of a procedure and post-surgical care. In addition, the Writing Committee has highlighted key research questions where current evidence is lacking. The Writing Committee believes that following these recommendations will help healthcare professionals to provide better care and will reduce the burden of diabetes related foot complications.

Performance of non-invasive bedside vascular testing in the prediction of wound healing or amputation among people with foot ulcers in diabetes: A systematic review

INTRODUCTION

The presence of peripheral artery disease (PAD) confers a significantly increased risk of failure to heal and major lower limb amputation for people with diabetes-related foot ulcer (DFU). Determining performance of non-invasive bedside tests for predicting likely DFU outcomes is therefore key to effective risk stratification of patients with DFU and PAD to guide management decisions. The aim of this systematic review was to determine the performance of non-invasive bedside tests for PAD to predict DFU healing, healing post-minor amputation, or need for minor or major amputation in people with diabetes and DFU or gangrene.

METHODS

A database search of Medline and Embase was conducted from 1980 to 30 November 2022. Prospective studies that evaluated non-invasive bedside tests in patients with diabetes, with and without PAD and foot ulceration or gangrene to predict the outcomes of DFU healing, minor amputation, and major amputation with or without revascularisation, were eligible. Included studies were required to have a minimum 6-month follow-up period and report adequate data to calculate the positive likelihood ratio (PLR) and negative likelihood ratio for the outcomes of DFU healing, and minor and major amputation. Methodological quality was assessed using the Quality in Prognosis Studies tool.

RESULTS

From 14,820 abstracts screened 28 prognostic studies met the inclusion criteria. The prognostic tests evaluated by the studies included: ankle-brachial index (ABI) in 9 studies; ankle pressures in 10 studies, toe-brachial index in 4 studies, toe pressure in 9 studies, transcutaneous oxygen pressure (TcPO2 ) in 7 studies, skin perfusion pressure in 5 studies, continuous wave Doppler (pedal waveforms) in 2 studies, pedal pulses in 3 studies, and ankle peak systolic velocity in 1 study. Study quality was variable. Common reasons for studies having a moderate or high risk of bias were poorly described study participation, attrition rates, and inadequate adjustment for confounders. In people with DFU, toe pressure ≥30 mmHg, TcPO2 ≥25 mmHg, and skin perfusion pressure of ≥40 mmHg were associated with a moderate to large increase in pretest probability of healing in people with DFU. Toe pressure ≥30 mmHg was associated with a moderate increase in healing post-minor amputation. An ABI using a threshold of ≥0.9 did not increase the pretest probability of DFU healing, whereas an ABI <0.5 was associated with a moderate increase in pretest probability of non-healing. Few studies investigated amputation outcomes. An ABI <0.4 demonstrated the largest increase in pretest probability of a major amputation (PLR ≥10).

CONCLUSIONS

Prognostic capacity of bedside testing for DFU healing and amputation is variable. A toe pressure ≥30 mmHg, TcPO2 ≥25 mmHg, and skin perfusion pressure of ≥40 mmHg are associated with a moderate to large increase in pretest probability of healing in people with DFU. There are little data available evaluating the prognostic capacity of bedside testing for healing after minor amputation or for major amputation in people with DFU. Current evidence suggests that an ABI <0.4 may be associated with a large increase in risk of major amputation. The findings of this systematic review need to be interpreted in the context of limitations of available evidence, including varying rates of revascularisation, lack of post-revascularisation bedside testing, and heterogenous subpopulations.

Von Willebrand factor hyperactivity affects the outcome of lower limb revascularization in subjects with type 2 diabetes mellitus complicated by diabetic foot vasculopathy: An observational pilot study

Aim of this study is to evaluate any differences in VWF antigen, VWF activity and ADAMTS-13 activity before and after successful and non-successful Percutaneous Transluminal Angioplasty (PTA) in subjects with type 2 diabetes (T2DM) complicated by Chronic limb-threatening ischemia (CLTI) in diabetic foot vasculopathy.

METHODS

In this prospective observational pilot study, we enrolled 35 T2DM subjects who underwent lower limb PTA. Transcutaneous oximetry was performed in all patients before and 6 weeks after PTA. The change in oxygen partial pressure (TcpO2) before and after PTA was expressed as TcpO2-delta (ΔTcpO2). VWF antigen, VWF activity and ADAMTS-13 activity were measured before and 6 weeks after PTA; changes were expressed as delta and ratio from baseline.

RESULTS

Subjects with ∆TcpO2 < 15 mmHg presented higher ΔVWF activity (p = 0.050) and lower ADAMTS-13 activity ratio (p = 0.080). Subjects with ∆TcpO2 < 30 mmHg showed lower ADAMTS-13 activity Δ and ratio (p = 0.028).

CONCLUSIONS

VWF antigen levels and VWF activity may potentially affect PTA outcome. Higher levels of VWF could derive from VWF release as consequence of PTA-induced mechanical endothelial damage and/or oxidative stress-induced modifications of VWF structure with impairment of VWF-ADAMTS13 interactions.

The intersocietal IWGDF, ESVS, SVS guidelines on peripheral artery disease in people with diabetes mellitus and a foot ulcer

Diabetes related foot complications have become a major cause of morbidity and are implicated in most major and minor amputations globally. Approximately 50% of people with diabetes and a foot ulcer have peripheral artery disease (PAD) and the presence of PAD significantly increases the risk of adverse limb and cardiovascular events. The International Working Group on the Diabetic Foot (IWGDF) has published evidence based guidelines on the management and prevention of diabetes related foot complications since 1999. This guideline is an update of the 2019 IWGDF guideline on the diagnosis, prognosis, and management of peripheral artery disease in people with diabetes mellitus and a foot ulcer. For this updated guideline, the IWGDF, the European Society for Vascular Surgery, and the Society for Vascular Surgery decided to collaborate to develop a consistent suite of recommendations relevant to clinicians in all countries. This guideline is based on three new systematic reviews. Using the Grading of Recommendations, Assessment, Development and Evaluation framework clinically relevant questions were formulated, and the literature was systematically reviewed. After assessing the certainty of the evidence, recommendations were formulated which were weighed against the balance of benefits and harms, patient values, feasibility, acceptability, equity, resources required, and when available, costs. Through this process five recommendations were developed for diagnosing PAD in a person with diabetes, with and without a foot ulcer or gangrene. Five recommendations were developed for prognosis relating to estimating likelihood of healing and amputation outcomes in a person with diabetes and a foot ulcer or gangrene. Fifteen recommendations were developed related to PAD treatment encompassing prioritisation of people for revascularisation, the choice of a procedure and post-surgical care. In addition, the Writing Committee has highlighted key research questions where current evidence is lacking. The Writing Committee believes that following these recommendations will help healthcare professionals to provide better care and will reduce the burden of diabetes related foot complications.

The Intersocietal IWGDF, ESVS, SVS Guidelines on Peripheral Artery Disease in People With Diabetes Mellitus and a Foot Ulcer

Diabetes related foot complications have become a major cause of morbidity and are implicated in most major and minor amputations globally. Approximately 50% of people with diabetes and a foot ulcer have peripheral artery disease (PAD) and the presence of PAD significantly increases the risk of adverse limb and cardiovascular events. The International Working Group on the Diabetic Foot (IWGDF) has published evidence based guidelines on the management and prevention of diabetes related foot complications since 1999. This guideline is an update of the 2019 IWGDF guideline on the diagnosis, prognosis, and management of peripheral artery disease in people with diabetes mellitus and a foot ulcer. For this updated guideline, the IWGDF, the European Society for Vascular Surgery, and the Society for Vascular Surgery decided to collaborate to develop a consistent suite of recommendations relevant to clinicians in all countries. This guideline is based on three new systematic reviews. Using the Grading of Recommendations, Assessment, Development and Evaluation framework clinically relevant questions were formulated, and the literature was systematically reviewed. After assessing the certainty of the evidence, recommendations were formulated which were weighed against the balance of benefits and harms, patient values, feasibility, acceptability, equity, resources required, and when available, costs. Through this process five recommendations were developed for diagnosing PAD in a person with diabetes, with and without a foot ulcer or gangrene. Five recommendations were developed for prognosis relating to estimating likelihood of healing and amputation outcomes in a person with diabetes and a foot ulcer or gangrene. Fifteen recommendations were developed related to PAD treatment encompassing prioritisation of people for revascularisation, the choice of a procedure and post-surgical care. In addition, the Writing Committee has highlighted key research questions where current evidence is lacking. The Writing Committee believes that following these recommendations will help healthcare professionals to provide better care and will reduce the burden of diabetes related foot complications.

Techniques Providing Endpoints for Revascularization in Chronic Limb-Threatening Ischemia

It is frequently difficult to estimate the revascularization endpoint in patients with chronic limb-threatening ischemia where there may be extensive multifocal multiarterial disease. There have been attempts to identify an endpoint for revascularization procedures, but none has become the standard of care. An ideal indicator of an endpoint can objectively quantify tissue perfusion, predict wound healing, and is easily and efficiently used intraprocedurally to assist real-time decision making on whether adequate perfusion has been reached. Candidate techniques to evaluate endpoints post-revascularization are discussed here.

Non-surgical treatment for arterial leg ulcers: a narrative review

Objectives:

Arterial leg ulcers (ALUs) pose a considerable burden on patients and health services. The cornerstone of treatment is revascularisation; however, this is not always possible and does not necessarily guarantee ulcer healing. Alternative treatment options are therefore also important. This narrative review aims to summarise the evidence available for non-surgical treatment of ALUs, including topical therapy, pharmacological agents, therapeutic angiogenesis and devices.

Methods:

A literature search was performed in November 2020 to identify studies reporting data on the non-surgical management of ALUs. Prospective randomised controlled trials (RCTs), controlled clinical trials and meta-analyses that investigated conservative or medical interventions on patients with intractable ALUs, and which provided quantitative data on ulcer healing were included. Following screening, studies that met the inclusion criteria underwent a data extraction process and findings were synthesised and categorised narratively.

Results:

In total, 14 controlled trials were selected for inclusion and analysed based on experimental protocol and outcome measures.

Conclusion:

There is some evidence available for the use of short-term systemic prostanoids, ultrasound therapy and pneumatic compression. There are limitations to these options including side effects, patient tolerance due to pain and availability in clinical practice. Further research is needed to improve treatment options for this complex group.

The Impact of Extracorporeal Shock Wave Therapy on Microcirculation in Diabetic Feet: A Pilot Study

BACKGROUND

Patients with diabetic foot commonly experience vascular insufficiency and compromised tissue perfusion. Extracorporeal shockwave therapy (ESWT) reportedly promotes wound healing and angiogenesis, but clinical studies on the effect of ESWT on angiogenesis are scarce and the exact mechanism remains unclear.

OBJECTIVE

To investigate the effect of ESWT on cutaneous microcirculation in diabetic feet.

METHODS

Ten patients with diabetic feet received ESWT twice weekly for a total of six sessions. Transcutaneous partial oxygen pressure (TcPO2) and cutaneous blood flow were measured before and after ESWT.

MAIN RESULTS

The treated feet showed statistically significant improvements in the mean TcPO2 (P < .01) and cutaneous blood flow level (P < .05) compared with control feet. In treated feet, TcPO2 increased by 19.6%, from 41.4 ± 9.9 to 49.5 ± 8.7 mm Hg (P < .05). In control feet, TcPO2 decreased by 11.6%, from 39.5 ± 14.0 to 34.9 ± 14.5 mm Hg (P = .059). The average cutaneous blood flow level of treated feet before ESWT was 36.9 ± 25.6, which increased to 48.3 ± 32.4 AU after ESWT (30.9% increase; P = .646). In control feet, the cutaneous blood flow level decreased from 80.5 ± 36.7 to 60.4 ± 38.8 AU, a decrease of 25.0% (P = .241).

CONCLUSIONS

These results demonstrate that ESWT may have beneficial effects on microcirculation in diabetic feet.

Performance of prognostic markers in the prediction of wound healing or amputation among patients with foot ulcers in diabetes: A systematic review

Clinical outcomes of patients with diabetes, foot ulceration, and peripheral artery disease (PAD) are difficult to predict. The prediction of important clinical outcomes, such as wound healing and major amputation, would be a valuable tool to help guide management and target interventions for limb salvage. Despite the existence of a number of classification tools, no consensus exists as to the most useful bedside tests with which to predict outcome. We here present an updated systematic review from the International Working Group of the Diabetic Foot, comprising 15 studies published between 1980 and 2018 describing almost 6800 patients with diabetes and foot ulceration. Clinical examination findings as well as six non-invasive bedside tests were evaluated for their ability to predict wound healing and amputation. The most useful tests to inform on the probability of healing were skin perfusion pressure ≥ 40 mmHg, toe pressure ≥ 30 mmHg, or TcPO₂  ≥ 25 mmHg. With these thresholds, all of these tests increased the probability of healing by greater than 25% in at least one study. To predict major amputation, the most useful tests were ankle pressure < 50 mmHg, ABI < 0.5, toe pressure < 30 mmHg, and TcPO₂  < 25 mmHg, which increased the probability of major amputation by greater than 25%. These indicative values may be used as a guide when deciding which patients are at highest risk for poor outcomes and should therefore be evaluated for revascularization at an early stage. However, this should always be considered within the wider context of important co-existing factors such as infection, wound characteristics, and other comorbidities.

Predictors of Major Adverse Limb Events after Open Forefoot Amputation in Patients with Chronic Limb-Threatening Ischemia

BACKGROUND

Management of patients with chronic limb-threatening ischemia (CLTI) and extensive foot necrosis presents a challenge for limb salvage. Our study evaluates preoperative risk factors that contributed to durability and efficacy of limb salvage after open transmetatarsal amputation (TMA) in patients with critical limb-threatening ischemia.

METHODS

We abstracted data from patients who underwent open TMA at Los Angeles County-University of Southern California Medical Center and Keck Hospital of University of Southern California from 2009 to 2018. Multivariable logistic regression analysis, adjusting for preoperative risk factors, was used to examine predictors of major adverse limb events (MALE). The aim was to evaluate outcomes following open TMA with MALE as the primary outcome. Our hypotheses were that outcomes would be worse for patients with foot infections and renal failure.

RESULTS

Forty-three open TMAs were done in 39 patients during the study period. The cohort had a mean age of 63 ± 11.6 years, 89% had a history of diabetes, 95% hypertension (HTN), 54% had end-stage renal disease (ESRD), and 26% were current smokers. MALE occurred in 39% of the cohort. Sex, race, indication, HTN, smoking status, and history of prior ipsilateral revascularization or minor amputations were not associated with MALE (P > 0.05). Multivariate logistic regression found ESRD to be an independent predictor of MALE (odds ratio 7.43, 95% confidence interval 1.12-49.17, P = 0.038) after adjusting for clinically significant covariates.

CONCLUSIONS

Open TMA provides acceptable rates of limb salvage for complex patients with CLTI. ESRD is an independent risk factor for MALE following open TMA in these patients. Vigilant follow-up is essential for this morbid patient population given poorer outcomes after forefoot amputation.

Letter Regarding "The Prostacyclin Analogue Iloprost as an Early Predictor of Successful Revascularization in Diabetic Patients Affected by Critical Limb Ischemia and Foot Ulcers"

PURPOSE

The aim of this study is to evaluate the role of Iloprost as an early predictor of successful revascularization in patients affected by ischemic diabetic foot ulcers (DFUs).

METHODS

Consecutive patients with ischemic DFUs with persistent low TcPO2 (<30mmHg) one day after a technical successful Percutaneous Transluminal Angioplasty (PTA) have been included. All patients underwent Iloprost infusion and TcPO2 has been recorded at days 3, 14 and 30. According to the TcPO2 reported at day 3, patients were divided into two groups: group A (patients with TcPO2 ≥30mmHg) and group B (patients with TcPO2 <30mmHg). Baseline TcPO2 values at days 3, 14 and 30 after Iloprost infusion and needing of re-intervention (re-PTA) have been evaluated.

RESULTS

Twenty-five patients have been included, 12/25 (48%) in Group A and 13/25 (52%) in Group B. There were no significant differences at the baseline and one day after PTA between the two groups while TcPO2 values recorded in Group A at days 3, 14 and 30 after Iloprost infusion were significant higher in comparison to the Group B (χ = 0.005). The rate of re-PTA were respectively 33,3% (Group A) and 53,8% (Group B) (p = 0.03).

CONCLUSIONS

Iloprost may be an early predictor of successful revascularization in patients affected by critical limb ischemia (CLI) and DFUs.

Review of Transmetatarsal Amputations in the Management of Peripheral Arterial Disease in an Asian Population

Objective: To evaluate outcomes after transmetatarsal amputation (TMA) in peripheral arterial disease (PAD) limb salvage in an Asian population and identify risk factors associated with TMA failure. Methodology: A retrospective review of 147 patients with PAD, who had undergone TMA between 2008 and 2014, was carried out. Univariate and multivariate analysis were used to identify predictors of TMA failure. Kaplan-Meier survival analysis was used to calculate major amputation and all-cause mortality rates. Results: The mean age was 66 years. 92% were diabetic patients and 78% had preceded angioplasty. 56% of TMAs were healed via secondary intention, 8% required subsequent split-thickness skin graft closure, 24% required further debridement while 37% had wounds, which failed to heal and required below-knee amputations (BKA). Multivariate analysis showed that diabetes is the only independent predictor of TMA failure (odds ratio (OR) 7.11, p=0.064). Patients with TMA failure were at increased risk of developing nosocomial infections (p=0.025) and faced a higher risk of 30-day re-admission rate (p=0.002). Conclusion: The success rate for PAD limb salvage TMA was 63% and diabetes was an independent predictor of TMA failure. Patients with TMA failure were at increased risks of nosocomial infections, and 30-day re-admissions; hence the risks and benefits of TMA for diabetic foot limb salvage must be individualized for each patient.

Evaluation of skeletal muscle microvascular perfusion of lower extremities by cardiovascular magnetic resonance arterial spin labeling, blood oxygenation level-dependent, and intravoxel incoherent motion techniques

BACKGROUND

Noninvasive cardiovascular magnetic resonance (CMR) techniques including arterial spin labeling (ASL), blood oxygenation level-dependent (BOLD), and intravoxel incoherent motion (IVIM), are capable of measuring tissue perfusion-related parameters. We sought to evaluate and compare these three CMR techniques in characterizing skeletal muscle perfusion in lower extremities and to investigate their abilities to diagnose and assess the severity of peripheral arterial disease (PAD).

METHODS

Fifteen healthy young subjects, 14 patients with PAD, and 10 age-matched healthy old subjects underwent ASL, BOLD, and IVIM CMR perfusion imaging. Healthy young and healthy old participants were subjected to a cuff-induced ischemia experiment with pressures of 20 mmHg and 40 mmHg above systolic pressure during imaging. Perfusion-related metrics, including blood flow, T2* relaxation time, perfusion fraction f, diffusion coefficient D, and pseudodiffusion coefficient D*, were measured in the anterior, lateral, soleus, and gastrocnemius muscle groups. Friedman, Mann-Whitney, Wilcoxon signed rank, and Spearman rank correlation tests were used for statistical analysis.

RESULTS

In cases of significant differences determined by the Friedman test (P < 0.05), blood flow, T2*, and D values gradually decreased, while f values showed a tendency to increase in healthy subjects under cuff compression. No significant correlations were found among the ASL, BOLD, and IVIM parameters (all P > 0.05). Blood flow and T2* values showed significant positive correlations with transcutaneous oxygen pressure measurements (ρ = 0.465 and 0.522, respectively; both P ≤ 0.001), while f values showed a significant negative correlation in healthy young subjects (ρ = - 0.351; P = 0.018). T2* was independent of age in every muscle group. T2* values were significantly decreased in PAD patients compared with healthy old subjects and severe PAD patients compared with mild-to-moderate PAD patients (all P < 0.0125). Significant correlations were found between T2* and ankle-brachial index values in all muscle groups in PAD patients (ρ = 0.644-0.837; all P < 0.0125). Other imaging parameters failed to show benefits towards the diagnosis and disease severity evaluation of PAD.

CONCLUSIONS

ASL, BOLD, and IVIM provide complementary information regarding tissue perfusion. Compared with ASL and IVIM, BOLD may be a more reliable technique for assessing PAD in the resting state and could thus be applied together with angiography in clinical studies as a tool to comprehensively assess microvascular and macrovascular properties in PAD patients.

Influence of Negative-Pressure Wound Therapy on Tissue Oxygenation in Diabetic Feet

OBJECTIVE

Negative-pressure wound therapy (NPWT) has become a common wound care treatment modality for a variety of wounds. Several previous studies have reported that NPWT increases blood flow in the wound bed. However, NPWT might decrease tissue oxygenation in the wound bed because the foam sponge of NPWT compresses the wound bed under the influence of the applied negative pressure. Adequate tissue oxygenation is an essential consideration during diabetic foot management, and the foot is more sensitive to ischemia than any other region. Furthermore, the issue as to whether NPWT reduces or increases tissue oxygenation in diabetic feet has never been correctly addressed. The aim of this study was to evaluate the influence of NPWT on tissue oxygenation in diabetic feet.

PARTICIPANTS

Transcutaneous partial oxygen pressures (TcPO2) were measured to determine tissue oxygenation levels beneath NPWT dressings on 21 feet of 21 diabetic foot ulcer patients.

DESIGN

A TcPO2 sensor was fixed at the tarsometatarsal area of contralateral unwounded feet. A suction pressure of -125 mm Hg was applied until TcPO2 reached a steady state. The TcPO2 values for diabetic feet were measured before, during, and after NPWT.

MAIN RESULTS

The TcPO2 levels decreased significantly after applying NPWT in all patients. Mean TcPO2 values before, during, and after therapy were 44.6 (SD, 15.2), 6.0 (SD, 7.1), and 40.3 (SD, 16.4) mm Hg (P < .01), respectively.

CONCLUSION

These results show that NPWT significantly reduces tissue oxygenation levels in diabetic feet.

Endovascular Devices and Revascularization Techniques for Limb-Threatening Ischemia in Individuals With Diabetes

Diabetes mellitus (DM) is a rapidly worsening global epidemic over the last thirty-five years. The increased prevalence of DM has changed the phenotypic expression of atherosclerotic limb threatening ischemia (LTI), resulting in an increase in lesions in the tibial vessels. These patients are also afflicted with peripheral neuropathy, foot deformities, and medial calcification of the vasculature. In response to the evolving phenotype of atherosclerosis, newer minimally invasive tools and techniques have been developed to improve the blood supply in LTI. Arterial access, traditionally obtained from the contralateral common femoral artery (CFA) in a retrograde fashion, is now also frequently being obtained in the ipsilateral limb in an antegrade fashion. Retrograde access of the tibial, pedal, tarsal, or calf collateral vessels is also being utilized to provide a route through which wires, catheters, balloons and stents may be placed. Wires have evolved to have a variety of diameters, materials and coatings providing interventionalists with a wide variety of choices when attempting to traverse blockages in the arteries. When catheters and wires fail to traverse the lesion, newer chronic total occlusion (CTO) devices have been developed to aid in the placement of a wire across the offending lesions. Due to medial calcification associated with DM, atherectomy devices have been developed to debulk the atherosclerotic plaque within the vessel. High pressure balloon angioplasty with or without stents remain the mainstay of intervention, with drug-coated balloons (DCBs) and drug-eluting stents (DESs) now being frequently used to prevent reocclusions of atherosclerotic lesions.

Can macrocirculation changes predict nonhealing diabetic foot ulcers?

PURPOSE

Transcutaneous partial oxygen tension (TcpO2) is considered the gold standard for assessment of tissue oxygenation, which is an essential factor for wound healing. The purpose of this study was to evaluate the association between macrocirculation and TcpO2 in persons with diabetes mellitus.

SUBJECTS AND SETTING

Ninety-eight patients with diabetic foot ulcers participated in the study (61 men and 37 women). The subjects had a mean age of 66.6 years (range, 30-83 years) and were treated at the Diabetic Wound Center of Korea University Guro Hospital, Seoul, Republic of Korea.

METHODS

Macrocirculation was evaluated using 2 techniques: computed tomographic angiography and Doppler ultrasound. Macrocirculation scores were based on the patency of the two tibial arteries in 98 patients. Computed tomographic angiography and Doppler ultrasound scores (0-4 points) were given according to intraluminal filling defects and arterial pulse waveform of each vessel, respectively. Tissue oxygenation was measured by TcpO2. Macrocirculation scores were statistically analyzed as a function of the TcpO2.

RESULTS

Statistical analysis revealed no significant linear trend between the macrocirculation status and TcpO2. Biavariate analysis using the Fisher exact test, Mantel-Haenszel tests, and McNemar-Bowker tests also found no significant relationship between macrocirculation and TcpO2.

CONCLUSIONS

Computed tomographic angiography and Doppler ultrasound are not sufficiently reliable substitutes for TcpO2 measurements in regard to determining the optimal treatment for diabetic patients.

Performance of prognostic markers in the prediction of wound healing or amputation among patients with foot ulcers in diabetes: a systematic review

Prediction of wound healing and major amputation in patients with diabetic foot ulceration is clinically important to stratify risk and target interventions for limb salvage. No consensus exists as to which measure of peripheral artery disease (PAD) can best predict outcomes. To evaluate the prognostic utility of index PAD measures for the prediction of healing and/or major amputation among patients with active diabetic foot ulceration, two reviewers independently screened potential studies for inclusion. Two further reviewers independently extracted study data and performed an assessment of methodological quality using the Quality in Prognostic Studies instrument. Of 9476 citations reviewed, 11 studies reporting on 9 markers of PAD met the inclusion criteria. Annualized healing rates varied from 18% to 61%; corresponding major amputation rates varied from 3% to 19%. Among 10 studies, skin perfusion pressure ≥ 40 mmHg, toe pressure ≥ 30 mmHg (and ≥ 45 mmHg) and transcutaneous pressure of oxygen (TcPO2 ) ≥ 25 mmHg were associated with at least a 25% higher chance of healing. Four studies evaluated PAD measures for predicting major amputation. Ankle pressure < 70 mmHg and fluorescein toe slope < 18 units each increased the likelihood of major amputation by around 25%. The combined test of ankle pressure < 50 mmHg or an ankle brachial index (ABI) < 0.5 increased the likelihood of major amputation by approximately 40%. Among patients with diabetic foot ulceration, the measurement of skin perfusion pressures, toe pressures and TcPO2 appear to be more useful in predicting ulcer healing than ankle pressures or the ABI. Conversely, an ankle pressure of < 50 mmHg or an ABI < 0.5 is associated with a significant increase in the incidence of major amputation.

Advanced Noncontrast MR Imaging in Musculoskeletal Radiology

Multiple nonmorphologic magnetic resonance sequences are available in musculoskeletal imaging that can provide additional information to better characterize and diagnose musculoskeletal disorders and diseases. These sequences include blood-oxygen-level-dependent (BOLD), arterial spin labeling (ASL), diffusion-weighted imaging (DWI), and diffusion-tensor imaging (DTI). BOLD and ASL provide different methods to evaluate skeletal muscle microperfusion. The BOLD signal reflects the ratio between oxyhemoglobin and deoxyhemoglobin. ASL uses selective tagging of inflowing blood spins in a specific region for calculating local perfusion. DWI and DTI provide information about the structural integrity of soft tissue including muscles and fibers as well as pathologies.

Diagnosis and assessment of peripheral arterial disease in the diabetic foot

Approximately half of all patients with a diabetic foot ulcer have co-existing peripheral arterial disease. Identifying peripheral arterial disease among patients with foot ulceration is important, given its association with failure to heal, amputation, cardiovascular events and increased risk of premature mortality. Infection, oedema and neuropathy, often present with ulceration, may adversely affect the performance of diagnostic tests that are reliable in patients without diabetes. Early recognition and expert assessment of peripheral arterial disease allows measures to be taken to reduce the risk of amputation and cardiovascular events, while determining the need for revascularization to promote ulcer healing. When peripheral arterial disease is diagnosed, the extent of perfusion deficit should be measured. Patients with a severe perfusion deficit, likely to affect ulcer healing, will require further imaging to define the anatomy of disease and indicate whether a revascularization procedure is appropriate.

Safety and efficacy of sustained release of basic fibroblast growth factor using gelatin hydrogel in patients with critical limb ischemia

As a form of therapeutic angiogenesis, we sought to investigate the safety and efficacy of a sustained-release system of basic fibroblast growth factor (bFGF) using biodegradable gelatin hydrogel in patients with critical limb ischemia (CLI). We conducted a phase I-IIa study that analyzed 10 CLI patients following a 200-μg intramuscular injection of bFGF-incorporated gelatin hydrogel microspheres into the ischemic limb. Primary endpoints were safety and transcutaneous oxygen pressure (TcO2) at 4 and 24 weeks after treatment. During the follow-up, there was no death or serious procedure-related adverse event. After 24 weeks, TcO2 (28.4 ± 8.4 vs. 46.2 ± 13.0 mmHg for pretreatment vs after 24 weeks, p < 0.01) showed significant improvement. Regarding secondary endpoints, the distance walked in 6 min (255 ± 105 vs. 318 ± 127 m, p = 0.02), the Rutherford classification (4.4 ± 0.5 vs. 3.1 ± 1.4, p = 0.02), the rest pain scale (1.7 ± 1.0 vs. 1.2 ± 1.3, p = 0.03), and the cyanotic scale (2.0 ± 1.1 vs. 0.9 ± 0.9, p < 0.01) also showed improvement. The blood levels of bFGF were within the normal range in all patients. A subanalysis of patients with arteriosclerosis obliterans (n = 7) or thromboangiitis obliterans (Buerger's disease) (n = 3) revealed that TcO2 had significantly improved in both subgroups. TcO2 did not differ between patients with or without chronic kidney disease. The sustained release of bFGF from biodegradable gelatin hydrogel may offer a safe and effective form of angiogenesis for patients with CLI.

Wound dehiscence and stump infection after lower limb amputation: risk factors and association with antibiotic use

BACKGROUND

Optimal duration of antibiotic prophylaxis following major lower limb amputation in preventing adverse stump outcomes is controversial.

OBJECTIVE

We assess the epidemiology and risk factors of wound dehiscence and stump infection after mid-thigh to transmetatarsal amputations with regard to antibiotic administration.

METHODS

Our retrospective observational study at the Geneva University Hospital (January 1995-June 2010) includes a total of 289 amputations in 270 adult patients (199 males; median age 70 years).

RESULTS

Wound dehiscence and/or stump infection occurred in 47 (16.3%) and 63 (21.8%) patients with a median delay of 24 and 14 days, respectively. No clinical variable was significantly associated with stump infection. Diabetes and older age (>80 years) were associated with dehiscence. Importantly, transcutaneous tissue oxygen tension (TcPO2) and duration of antibiotic administration showed no association with either outcome.

CONCLUSION

The duration of antibiotic administration before or after surgery does not change the epidemiology of stump complications.

Autologous bone marrow mononuclear cell therapy is safe and promotes amputation-free survival in patients with critical limb ischemia

OBJECTIVE

The purpose of this Phase I open label nonrandomized trial was to assess the safety and efficacy of autologous bone marrow mononuclear cell (ABMNC) therapy in promoting amputation-free survival (AFS) in patients with critical limb ischemia (CLI).

METHODS

Between September 2005 and March 2009, 29 patients (30 limbs), with a median age of 66 years (range, 23-84 years; 14 male, 15 female) with CLI were enrolled. Twenty-one limbs presented with rest pain (RP), six with RP and ulceration, and three with ulcer only. All patients were not candidates for surgical bypass due to absence of a patent artery below the knee and/or endovascular approaches to improving perfusion was not possible as determined by an independent vascular surgeon. Patients were treated with an average dose of 1.7 ± 0.7 × 10(9) ABMNC injected intramuscularly in the index limb distal to the anterior tibial tuberosity. The primary safety end point was accumulation of serious adverse events, and the primary efficacy end point was AFS at 1 year. Secondary end points at 12 weeks posttreatment were changes in first toe pressure (FTP), toe-brachial index (TBI), ankle-brachial index (ABI), and transcutaneous oxygen measurements (TcPO(2)). Perfusion of the index limb was measured with positron emission tomography-computed tomography (PET-CT) with intra-arterial infusion of H(2)O(15). RP, using a 10-cm visual analogue scale, quality of life using the VascuQuol questionnaire, and ulcer healing were assessed at each follow-up interval. Subpopulations of endothelial progenitor cells were quantified prior to ABMNC administration using immunocytochemistry and fluorescent-activated cell sorting.

RESULTS

There were two serious adverse events; however, there were no procedure-related deaths. Amputation-free survival at 1 year was 86.3%. There was a significant increase in FTP (10.2 ± 6.2 mm Hg; P = .02) and TBI (0.10 ± 0.05;P = .02) and a trend in improvement in ABI (0.08 ± 0.04; P = .73). Perfusion index by PET-CT H(2)O(15) increased by 19.3 ± 3.1, and RP decreased significantly by 2.2 ± 0.6 cm (P = .02). The VascuQol questionnaire demonstrated significant improvement in quality of life, and three of nine ulcers (33%) healed completely. KDR(+) but not CD34(+) or CD133(+) subpopulations of ABMNC were associated with improvement in limb perfusion.

CONCLUSION

This Phase I study has demonstrated safety, and the AFS rates suggest efficacy of ABMNC in promoting limb salvage in "no option" CLI. Based on these results, we plan to test the concept that ABMNCs improve AFS at 1 year in a Phase III randomized, double-blinded, multicenter trial.

Safety of a non-viral plasmid-encoding dual isoforms of hepatocyte growth factor in critical limb ischemia patients: a phase I study

We aimed to evaluate in a phase I dose-escalation study, the safety of intramuscular injections of a novel non-viral plasmid DNA expressing two isoforms of human hepatocyte growth factor (HGF) (VM202) in patients with critical limb ischemia (CLI). In total, 12 patients with CLI and unsuitable for revascularization were consecutively assigned to increasing doses (2 to 16 mg) of VM202 administered into the ischemic calf muscle at days 1 and 15. Patients were evaluated for safety and tolerability, changes in ankle- and toe brachial index (ABI and TBI), and pain severity score using a visual analog scale (VAS) throughout a 12-month follow-up period. Median age was 72 years and 53% of the patients were male. VM202 was safe and well tolerated with no death during the 12-month follow-up. Median ABI and TBI significantly increased from 0.35 to 0.52 (P=0.005) and from 0.15 to 0.24 (P=0.01) at 12 months follow-up. Median VAS decreased from 57.5 to 16.0 mm at 6 months follow-up (P=0.03). In this first human clinical trial, VM202, which expresses two isoforms of human HGF, appear to be safe and well tolerated with encouraging clinical results and thus supports the performance of a phase II randomized controlled trial.

Effect of percutaneous transluminal angioplasty on tissue oxygenation in ischemic diabetic feet

Percutaneous transluminal angioplasty (PTA) has been performed as an alternative to bypass surgery for improving tissue oxygenation in ischemic diabetic feet because the former is less invasive than the latter. The purpose of this study was to evaluate the effect of PTA on tissue oxygenation in ischemic diabetic feet. This study included 29 ischemic diabetic feet, as determined by a transcutaneous oxygen pressure (TcPO(2) )<30 mmHg. The PTA was carried out in 29 limbs. The PTA procedure was considered successful, acceptable, and failed when residual stenosis was<30%, between 30 and 50%, and>50%, respectively. For evaluation of tissue oxygenation, the foot TcPO(2) was measured before PTA and weekly for 6 weeks after PTA. Immediately after PTA, 26 feet were evaluated as being successful and the remaining three as acceptable. Before PTA, the average foot TcPO(2) was 12.7 ± 8.9 mmHg. The TcPO(2) values were increased to 43.6 ± 24.1, 51.0 ± 22.6, 58.3 ± 23.0, 61.3 ± 24.2, 59.0 ± 22.2, and 53.8 ± 21.0 mmHg 1, 2, 3, 4, 5, and 6 weeks after PTA, respectively (p<0.01). The PTA procedure significantly increases tissue oxygenation in ischemic diabetic feet. The maximal level of tissue oxygenation was measured on the fourth week following PTA.

Evolving techniques in foot and ankle amputation

Multiple clinical pathways lead to lower extremity amputation, including trauma, dysvascular disease, congenital defects, and malignancy. However, the principles of successful amputation-careful preoperative planning, coordination of a multidisciplinary team, and good surgical technique-remain the same. Organized rehabilitation and properly selected prostheses are integral components of amputee care. In the civilian setting, amputation is usually performed as a planned therapy for an unsalvageable extremity, not as an emergency procedure. The partial loss of a lower limb often represents a major change in a person's life, but patients should be encouraged to approach amputation as the beginning of a new phase of life and not as the culmination of previous treatment failures.

Diabetic foot infections: a team-oriented review of medical and surgical management

As the domestic and international incidence of diabetes and metabolic syndrome continues to rise, health care providers need to continue improving management of the long-term complications of the disease. Emergency department visits and hospital admissions for diabetic foot infections are increasingly commonplace, and a like-minded multidisciplinary team approach is needed to optimize patient care. Early recognition of severe infections, medical stabilization, appropriate antibiotic selection, early surgical intervention, and strategic plans for delayed reconstruction are crucial components of managing diabetic foot infections. The authors review initial medical and surgical management and staged surgical reconstruction of diabetic foot infections in the inpatient setting.

A stepwise approach to the surgical management of severe diabetic foot infections

Foot infections are common among diabetic patients with ulceration and are a major cause of hospitalization and lower extremity amputation. Aggressive and emergent surgical intervention is essential in the face of life- or limb-threatening infection to achieve limb salvage and survival. Critical limb ischemia, neuropathy, and an impaired host complicate the treatment of a severe diabetic foot infection. A severe diabetic foot infection carries a 25% risk of major amputation. For this reason, surgery should be coordinated with a well-functioning multidisciplinary team that specializes in diabetic limb preservation. Timing of surgery and strategies employed should be understood and agreed on by both the surgical and medical disciplines managing the diabetic patient with a limb-threatening infection. The overall strategy for surgically managing a severe diabetic foot infection is as follows: the first step is infection control through aggressive and extensive surgical debridement, the second step is a comprehensive vascular assessment with possible vascular surgery and/or endovascular intervention, and the final step is soft tissue and skeletal reconstruction after infection is eradicated to obtain wound closure and limb salvage. A consistent stepwise surgical approach combined with sound surgical principles is paramount for successful management of the severe diabetic foot infection. The authors discuss their stepwise surgical approach to reduce the mortality, morbidity, psychological distress, and length of hospitalization associated with life- or limb-threatening diabetic foot infections.

Use of a non-specific immunomodulation therapy as a therapeutic vasculogenesis strategy in no-option critical limb ischemia patients

BACKGROUND/AIMS

Inflammatory mediators contribute to the impairment of vasculogenesis by reducing endothelial progenitor cells (EPCs) mobilization in atherosclerotic vasculopathy. We tested the hypothesis that administration of an oxygen/ozone mixture (IMT) might counteract this pathophysiological mechanism and enhance limb tissue perfusion in patients with critical limb ischemia (CLI).

METHODS

Randomized patients with rest pain or ischemic ulcers and transcutaneous oxygen tension (TcPO(2)) <40 mmHg and/or toe pressure <50 mmHg received placebo (n=74) or a non-specific immunomodulation therapy (IMT) (n=77), autologous blood exposed to oxygen/ozone gas mixture by intragluteal injection, on day 1, 2, 7, and once a week thereafter for at least 22 weeks. Patients were evaluated for changes in TcPO(2), levels of circulating EPCs (CD34/KDR-positive cells) and inflammation (tumor necrosis factor-alpha-TNF-alpha).

RESULTS

TcPO(2) and CD34/CD133-positive cells increased at 22 weeks in IMT group (P<0.01) whereas no changes were observed in placebo group. TNF-alpha levels decreased at 6 months in IMT group (P<0.001) whereas no changes were observed in placebo group. There was a strong positive correlation between CD34/KDR-positive cells and TcPO(2) (r=0.56, P<0.01). Moreover, there was an inverse correlation between CD34/KDR-positive cells and TNF-alpha (r=-0.51, P<0.01).

CONCLUSIONS

Intramuscular injection of IMT may improve wound healing and limb salvage in patients with CLI.

The vascular and biochemical effects of cilostazol in patients with peripheral arterial disease

OBJECTIVES

Cilostazol improves walking distance and quality of life in patients with peripheral arterial disease (PAD). This study assessed the vascular and biochemical effects of cilostazol therapy in PAD patients.

METHODS

PAD patients were prospectively recruited to a randomized, double-blinded, placebo-controlled trial. Baseline clinical data were recorded. Clinical assessment included measurement of arterial compliance, transcutaneous oxygenation, ankle-brachial index (ABI), and treadmill walking distance. Blood analyses included a full blood panel, coagulation screen, urea and electrolytes, liver function tests, estimated glomerular filtration rate, and lipid profiles. Quality of life indices were recorded using validated generic and walking-specific questionnaires. All tests were performed at baseline, 6, and 24 weeks.

RESULTS

Eighty patients (53 men) were recruited from December 2004 to January 2006. The cilostazol group had a significant reduction in the augmentation index compared with the placebo group at 6 weeks (19.7% vs 26.7%, P = .001) and at 24 weeks (19.7% vs 27.7%, P = .005). A paradoxic reduction in transcutaneous oxygenation levels was identified in the cilostazol group for the left foot at 6 weeks and for the right foot at both 6 and 24 weeks. The ABIs were not significantly different between treatment groups at baseline, 6 weeks, or 24 weeks for the left and right lower limbs. The mean percentage change in walking distance from baseline improved more markedly in the cilostazol compared with the placebo group for absolute claudication distance at 6 (78.6% vs 26.4%, P = .20) and 24 weeks (173.1% vs 92.1%, P = .27); however, these failed to reach significance. Significant improvements in lipid profiles were demonstrated with cilostazol therapy at 6 weeks (triglycerides, high-density lipoprotein [HDL]) and at 24 weeks (cholesterol, triglycerides, HDL, and low-density lipoprotein). The cilostazol treatment group demonstrated significant improvements in the Short Form-36 (physical functioning, physical component score), Walking Impairment (distance and speed), and Vascular Quality of Life (pain) indices at 6 and 24 weeks. Although cilostazol was associated with side effects in approximately one-third of patients, most settled within 6 weeks, facilitating the continuation of therapy in >89%.

CONCLUSION

Cilostazol is a well-tolerated, safe, and efficacious treatment for PAD patients. It not only improves patients' symptomatology and quality of life but also appears to have beneficial effects on arterial compliance, possibly through its lipid-lowering property.

Is the foot elevation the optimal position for wound healing of a diabetic foot?

In managing diabetic foot ulcers, foot elevation has generally been recommended to reduce oedema and prevent other sequential problems. However, foot elevation may decrease tissue oxygenation of the foot more than the dependent position since the dependent position is known to increase blood flow within the arterial system. In addition, diabetic foot ulcers, which have peripheral vascular insufficiency, generally have less oedema than other wounds. Therefore, we argue that foot elevation may not be helpful for healing of vascularly compromised diabetic foot ulcers since adequate tissue oxygenation is an essential factor in diabetic wound healing. The purpose of this study was to evaluate the influence of foot height on tissue oxygenation and to determine the optimal foot position to accelerate wound healing of diabetic foot ulcers. This study included 122 cases (73 males and 47 females; two males had bilateral disease) of diabetic foot ulcer patients aged 40-93 years. Trans-cutaneous partial oxygen tension (TcpO(2)) values of diabetic feet were measured before and after foot elevation (n=21). Elevation was achieved by placing a foot over four cushions. We also measured foot TcpO(2) values before and after lowering the feet (n=122). Feet were lowered to the patient's tibial height, approximately 30-35 cm, beside a bed handrail. Due to the large number of lowering measurements, we divided them into five sub-groups according to initial TcpO(2.) Tissue oxygenation values were compared. Foot-elevation-lowered TcpO(2) values before and after elevation were 32.5+/-22.2 and 23.8+/-23.1 mmHg (p<0.01), respectively. Foot-lowering-augmented TcpO(2) values before and after lowering were 44.6+/-23.8 and 58.0+/-25.9 mmHg (p<0.01), respectively. The lower the initial TcpO(2) level, the more the TcpO(2) level increased. The foot lowering, rather than elevation, significantly augments TcpO(2) and may stimulate healing of diabetic foot ulcers.

Results of a Double-Blind, Placebo-Controlled Study to Assess the Safety of Intramuscular Injection of Hepatocyte Growth Factor Plasmid to Improve Limb Perfusion in Patients With Critical Limb Ischemia

Background— The Study to Assess the Safety of Intramuscular Injection of Hepatocyte Growth Factor Plasmid to Improve Limb Perfusion in Patients With Critical Limb Ischemia (HGF-STAT trial) determined the effect of hepatocyte growth factor (HGF) plasmid on safety and limb tissue perfusion as measured by transcutaneous oxygen tension (TcP o 2 ) in patients with critical limb ischemia (CLI).

Methods and Results— Randomized patients with rest pain or ischemic ulcers and TcP o 2 <40 mm Hg and/or toe pressure <50 mm Hg received placebo or HGF-plasmid intramuscular injection as follows: 0.4 mg at days 0, 14, and 28 (low dose); 4.0 mg at days 0 and 28 (middle dose); or 4.0 mg at days 0, 14, and 28 (high dose). Patients were evaluated for safety, changes in TcP o 2 and ankle and toe pressure, amputation, and wound healing. Ninety-three of 104 treated patients were evaluated for safety (mean age 70 years, 63% male, 53% diabetic, 64% with tissue loss, mean ankle-brachial index 0.41, and mean toe pressure 26 mm Hg). Adverse events occurred in 86% of the patients, most of which were related to CLI or comorbid conditions and were not different between groups. TcP o 2 (mean±SE) increased at 6 months in the high-dose group (24.0±4.2 mm Hg, 95% CI 15.5 to 32.4 mm Hg) compared with the placebo (9.4±4.2 mm Hg, 95% CI 0.9 to 17.8), low-dose (11.1±3.7 mm Hg, CI 3.7 to 18.7 mm Hg), and middle-dose (7.3±4.8 mm Hg, CI −2.2 to 17.0 mm Hg) groups (ANCOVA P =0.0015). There was no difference between groups in secondary end points, including ankle-brachial index, toe-brachial index, pain relief, wound healing, or major amputation.

Conclusions— Intramuscular injection of HGF plasmid was safe and well tolerated. Larger studies to determine whether HGF plasmid can improve wound healing and limb salvage in patients with CLI are warranted.

A stepwise approach to the surgical management of severe diabetic foot infections

Foot infections are common among diabetic patients with ulceration and are a major cause of hospitalization and lower extremity amputation. Aggressive and emergent surgical intervention is essential in the face of life- or limb-threatening infection to achieve limb salvage and survival. Critical limb ischemia, neuropathy, and an impaired host complicate the treatment of a severe diabetic foot infection. A severe diabetic foot infection carries a 25% risk of major amputation. For this reason, surgery should be coordinated with a well-functioning multidisciplinary team that specializes in diabetic limb preservation. Timing of surgery and strategies employed should be understood and agreed on by both the surgical and medical disciplines managing the diabetic patient with a limb-threatening infection. The overall strategy for surgically managing a severe diabetic foot infection is as follows: the first step is infection control through aggressive and extensive surgical debridement, the second step is a comprehensive vascular assessment with possible vascular surgery and/or endovascular intervention, and the final step is soft tissue and skeletal reconstruction after infection is eradicated to obtain wound closure and limb salvage. A consistent stepwise surgical approach combined with sound surgical principles is paramount for successful management of the severe diabetic foot infection. The authors discuss their stepwise surgical approach to reduce the mortality, morbidity, psychological distress, and length of hospitalization associated with life- or limb-threatening diabetic foot infections.

A review of the clinical significance of tissue hypoxia measurements in lower extremity wound management

The aim of this paper is to review techniques that are currently available to measure tissue hypoxia in order to benefit the management of wounds. Direct measurement of tissue partial oxygen pressure (PO(2)) is invasive and therefore unappealing in clinical practice. Several techniques (PET scans, MRI derived techniques) are primarily applicable to research rather than clinical applications. Imaging techniques (duplex ultrasonography, arteriography, MRI techniques) are recommended only as part of the workup for revascularisation. Techniques that assess local perfusion include clearance methods, transcutaneous O(2) and CO( 2) pressure measurement, and laser Doppler flowmetry and imaging. These techniques permit interpretation of altered perfusion states. Each technique offers subtly different information concerning microvascular function. All these techniques require strict protocols to derive reliable data. The potential of the promising near infrared reflectance spectroscopy (NIRS) technique is yet to be determined.

When is a technically successful peripheral angioplasty effective in preventing above-the-ankle amputation in diabetic patients with critical limb ischaemia?

AIM

To determine parameters predictive of avoidance of major (above-the-ankle) amputation after a technically successful peripheral angioplasty (PTA) in patients with diabetes with critical limb ischaemia.

METHODS

From January 1999 to December 2003, 420 consecutive patients with diabetes admitted to hospital because of critical limb ischaemia underwent peripheral angiography and concomitant technically successful PTA. Transcutaneous oxygen tension (TcPO(2)) was measured before and after PTA. Major amputation at 30 days was recorded.

RESULTS

After PTA, the iliac-femoral-popliteal axis was patent in all patients. In 67 patients, all three crural arteries were patent, in 143 patients 2 crural arteries were patent, and in 186 patients one crural artery was patent (104 peroneal, 62 anterior tibial, 20 posterior tibial). In 24 patients, all three crural arteries were occluded. Twenty-two major amputations were performed. Of these, 15 were performed in the 24 patients with occlusion of all the infrapopliteal arteries. Seven of the 186 patients in whom only the peroneal artery was patent required amputation. In patients not requiring amputation, TcPO(2) increased from 15.5 +/- 11.9 to 45.0 +/- 12.0 mmHg (P = 0.000), while in those requiring amputation, TcPO(2) increased from 9.6 +/- 7.7 to 18.6 +/- 8.1 mmHg (P < 0.082). Multivariate analysis indicated an independent role of occlusion of infrapopliteal arteries after PTA (OR 8.20 for every crural obstructed artery, P = 0.022, CI 1.35-49.6) and TcPO(2) after PTA (OR 0.80 for increase of 1 mmHg, P < 0.001, CI 0.74-0.88).

CONCLUSIONS

In patients with diabetes, PTA is effective in avoiding major amputation, provided recanalization occurs in at least one tibial artery down to the foot. In a few patients, re-canalization of the peroneal artery alone is not sufficient to avoid major amputation.

Predictive Values of Transcutaneous Oxygen Tension for Above-the-ankle Amputation in Diabetic Patients with Critical Limb Ischemia

OBJECTIVE

To assess the values of transcutaneous oxygen tension (TcPO2) capable of predicting above-the-ankle amputation in diabetic patients diagnosed for critical limb ischemia (CLI) according to the criteria of the TransAtlantic Inter-Society Consensus.

DESIGN

Retrospective study.

METHODS

From January 1999 to December 2003, 564 diabetic patients were consecutively hospitalized for CLI in one limb. Revascularization with angioplasty or bypass graft was performed when possible and, if not possible, prostanoid therapy was used. In patients in whom therapies did not relieve the rest pain or the gangrene was extended above the Chopart joint, an above-the-ankle-amputation was performed. After treatment TcPO2 values were evaluated in all patients at the dorsum of the foot.

RESULTS

Fifty-five (9.8%) patients underwent an above-the-ankle amputation: 22 of 420 patients who underwent angioplasty, 17 of 117 patients who underwent bypass (14.5%) and 16 of 27 patients in whom revascularization was not possible. Post-treatment TcPO2, measured by a receiver operating characteristic (ROC) curve, showed a value 34 mmHg as the best threshold for determining the need for revascularization, with an area under the curve of 0.89 (95%CI 0.85-0.94). Using logistic regression analysis the probability of above-the-ankle amputation for this threshold is 9.7% and reduces to 3% for TcPO2 > 40 mmHg.

CONCLUSION

TcPO2 levels<34 mmHg indicate the need for revascularization, while for values >or= 34 < 40 mmHg this need appears less pressing, although there remains a considerable probability of amputation. TcPO2 levels greater than 40 mmHg suggest that revascularization is dependent on the severity of tissue loss and possible morbidity caused by the procedure.

Spinal cord stimulation for ischemic heart disease and peripheral vascular disease

Ischemic disease (ID) is now an important indication for electrical neuromodulation (NM), particularly in chronic pain conditions. NM is defined as a therapeutic modality that aims to restore functions of the nervous system or modulate neural structures involved in the dysfunction of organ systems. One of the NM methods used is chronic electrical stimulation of the spinal cord (spinal cord stimulation: SCS). SCS in ID, as applied to ischemic heart disease (IHD) and peripheral vascular disease (PVD), started in Europe in the 1970s and 1980s, respectively. Patients with ID are eligible for SCS when they experience disabling pain, resulting from ischaemia. This pain should be considered therapeutically refractory to standard treatment intended to decrease metabolic demand or following revascularization procedures. Several studies have demonstrated the beneficial effect of SCS on IHD and PVD by improving the quality of life of this group of severely disabled patients, without adversely influencing mortality and morbidity. SCS used as additional treatment for IHD reduces angina pectoris (AP) in its frequency and intensity, increases exercise capacity, and does not seem to mask the warning signs of a myocardial infarction. Besides the analgesic effect, different studies have demonstrated an anti-ischemic effect, as expressed by different cardiac indices such as exercise duration, ambulatory ECG recording, coronary flow measurements, and PET scans. SCS can be considered as an alternative to open heart bypass grafting (CABG) for patients at high risk from surgical procedures. Moreover, SCS appears to be more efficacious than transcutaneous electrical nerve stimulation (TENS). The SCS implantation technique is relatively simple: implanting an epidural electrode under local anesthesia (supervised by the anesthesist) with the tip at T1, covering the painful area with paraesthesia by external stimulation (pulse width 210, rate 85 Hz), and connecting this electrode to a subcutaneously implanted pulse generator. In PVD the pain may manifest itself at rest or during walking (claudication), disabling the patient severely. Most of the patients suffer from atherosclerotic critical limb ischemia. All patients should be therapeutically refractory (medication and revascularization) to become eligible for SCS. Ulcers on the extremities should be minimal. In PVD the same implantation technique is used as in IHD except that the tip of the electrode is positioned at T10-11. In PVD the majority of the patients show significant reduction in pain and more than half of the patients show improvement of circulatory indices, as shown by Doppler, thermography, and oximetry studies. Limb salvage studies show variable results depending on the stage of the trophic changes. The underlying mechanisms of action of SCS in PVD require further elucidation.