Noninvasive assessment of lower extremity hemodynamics in individuals with diabetes mellitus

Ultrafast longitudinal imaging of haemodynamics via single-shot volumetric photoacoustic tomography with a single-element detector

Techniques for imaging haemodynamics use ionizing radiation or contrast agents or are limited by imaging depth (within approximately 1 mm), complex and expensive data-acquisition systems, or low imaging speeds, system complexity or cost. Here we show that ultrafast volumetric photoacoustic imaging of haemodynamics in the human body at up to 1 kHz can be achieved using a single laser pulse and a single element functioning as 6,400 virtual detectors. The technique, which does not require recalibration for different objects or during long-term operation, enables the longitudinal volumetric imaging of haemodynamics in vasculature a few millimetres below the skin's surface. We demonstrate this technique in vessels in the feet of healthy human volunteers by capturing haemodynamic changes in response to vascular occlusion. Single-shot volumetric photoacoustic imaging using a single-element detector may facilitate the early detection and monitoring of peripheral vascular diseases and may be advantageous for use in biometrics and point-of-care testing.

Single-shot 3D photoacoustic tomography using a single-element detector for ultrafast imaging of hemodynamics

Imaging hemodynamics is crucial for the diagnosis, treatment, and prevention of vascular diseases. However, current imaging techniques are limited due to the use of ionizing radiation or contrast agents, short penetration depth, or complex and expensive data acquisition systems. Photoacoustic tomography shows promise as a solution to these issues. However, existing photoacoustic tomography methods collect signals either sequentially or through numerous detector elements, leading to either low imaging speed or high system complexity and cost. To address these issues, here we introduce a method to capture a 3D photoacoustic image of vasculature using a single laser pulse and a single-element detector that functions as 6,400 virtual ones. Our method enables ultrafast volumetric imaging of hemodynamics in the human body at up to 1 kHz and requires only a single calibration for different objects and for long-term operations. We demonstrate 3D imaging of hemodynamics at depth in humans and small animals, capturing the variability in blood flow speeds. This concept can inspire other imaging technologies and find applications such as home-care monitoring, biometrics, point-of-care testing, and wearable monitoring.

Long-term results after internal partial forefoot amputation (resection): a retrospective analysis

INTRODUCTION

Internal partial forefoot amputation (IPFA) is a treatment option for osteomyelitis and refractory and recurrent chronic ulcers of the forefoot. The aim of our study was to assess the healing rate of chronic ulcers, risk of ulcer recurrence at the same area or re-ulceration at a different area and revision rate in patients treated with IPFA.

MATERIALS AND METHODS

All patients who underwent IPFA of a phalanx and/or metatarsal head and/or sesamoids at our institution because of chronic ulceration of the forefoot and/or osteomyelitis from 2004 to 2014 were included. Information about patient characteristics, ulcer healing, new ulcer occurrence, and revision surgery were collected. Kaplan-Meier survival curves were plotted for new ulcer occurrence and revision surgery.

RESULTS

A total of 102 patients were included (108 operated feet). 55.6% of our patients had diabetes. In 44 cases, an IPFA of a phalanx was performed, in 60 cases a metatarsal head resection and in 4 cases an isolated resection of sesamoids. The mean follow-up was 40.9 months. 91.2% of ulcers healed after a mean period of 1.3 months. In 56 feet (51.9%), a new ulcer occurred: 11 feet (10.2%) had an ulcer in the same area as initially (= ulcer recurrence), in 45 feet (41.7%) the ulcer was localized elsewhere (= re-ulceration). Revision surgery was necessary in 39 feet (36.1%). Only one major amputation and five complete transmetatarsal forefoot amputations were necessary during the follow-up period. Thus, the major amputation rate was 0.9%, and the minor amputation rate on the same ray was 13.9%.

CONCLUSIONS

IPFA is a valuable treatment of chronic ulcers of the forefoot. However, new ulceration is a frequent event following this type of surgery. Our results are consistent with the reported re-ulceration rate after conservative treatment of diabetic foot ulcers. The number of major amputations is low after IPFA.

LEVEL OF EVIDENCE

Retrospective Case Series Study (Level IV).

Post-exercise pulsatility index indicates treatment effects in peripheral arterial occlusive disease (PAOD)

Background

Hypothesis: Post-exercise measurements better discriminate PAOD-patients from healthy persons and they more sensitively detect hemodynamic improvements after treatment procedures than resting measurements.

Methods

A total of 19 healthy volunteers and 23 consecutive PAOD-patients underwent measurements of peak systolic velocity (PSV), end-diastolic velocity (EDV), minimal diastolic velocity (MDV), time-averaged maximum velocities (TAMAX), resistance index (RI) and pulsatility index (PI) before and after a standard exercise test (at 1, 2, 3, 4 and 5 min) before and after treatment (incl. epidemiological data, PAOD risk factors and comorbidities).

Results

In resting values, healthy persons and PAOD-patients did not differ significantly in any of the hemodynamic parameters. PSV increased after treatment in PAOD-patients by 5 cm/s (paired t‑test, p: 0.025); however, when the amplitude of autoregulatory changes related to the resting values were calculated, PAOD-patients showed clearly less hemodynamic changes after exercise than healthy persons (p: 0.04; 0.002; <0.001 for PSV, TAMAX and PI, resp.). The time course after exercise was compared by repeated measures of ANOVA. Healthy persons differed significantly in PI, RI and PSV from PAOD patients before and after treatment (p<0.001 each). The PAOD-patients revealed a significantly improved PI after treatment (p: 0.042). The only factor contributing significantly to PI independently from grouping was direct arterial vascularization as compared to discontinuous effects by an obstructed arterial tree.

Conclusion

Healthy persons cannot be well differentiated from PAOD-patients solely by hemodynamics at rest but by characteristic changes after standard exercise. Treatment effects are reflected by higher PI-values after exercise.

Reappraising Diabetic Foot Ulcers: A Focus on Mechanisms of Ulceration and Clinical Evaluation

Diabetic foot ulcers (DFU) are one of the most devastating complications of diabetes as they have significant effects on patient morbidity and mortality. Since their first description in the 19th century, our understanding of DFU has evolved as we uncover the mechanisms that mediate ulceration. In this review, we aim to summarize the various pathways that lead to the development of DFU in order to reappraise physicians' understanding of these complex wounds. Relevant pathways include the following: (1) neuropathy (motor neuropathy, loss of protective sensation, and autonomic sympathetic dysfunction), (2) vascular disease (arterial ischemia, venous insufficiency, and microvascular changes), and (3) metabolism (signaling and immunological effects of hyperglycemia). We also discuss the clinical presentation of DFU and an evidence-based evaluation to assist clinicians in early identification and classification of these wounds to inform management of DFU. Finally, we summarize complications of DFU caused by the various pathways mediating ulceration and briefly overview DFU management in order to educate physicians about the potential risks if left untreated. A better understanding of the synergistic pathways leading to DFU is essential for clinicians to improve DFU diagnosis, tailor intervention, and mitigate significant patient morbidity and mortality.

Guidelines on multidisciplinary approaches for the prevention and management of diabetic foot disease (2020 edition)

In recent years, as living standards have continued to improve, the number of diabetes patients in China, along with the incidence of complications associated with the disease, has been increasing. Among these complications, diabetic foot disease is one of the main causes of disability and death in diabetic patients. Due to the differences in economy, culture, religion and level of medical care available across different regions, preventive and treatment methods and curative results for diabetic foot vary greatly. In multidisciplinary models built around diabetic foot, the timely assessment and diagnosis of wounds and appropriate methods of prevention and treatment with internal and external surgery are key to clinical practice for this pathology. In 2019, under the leadership of the Jiangsu Medical Association and Chinese Diabetes Society, the writing group for the Guidelines on multidisciplinary approaches for the prevention and management of diabetic foot disease (2020 edition) was established with the participation of scholars from the specialist areas of endocrinology, burn injury, vascular surgery, orthopedics, foot and ankle surgery and cardiology. Drawing lessons from diabetic foot guidelines from other countries, this guide analyses clinical practices for diabetic foot, queries the theoretical basis and grades and gives recommendations based on the characteristics of the pathology in China. This paper begins with assessments and diagnoses of diabetic foot, then describes treatments for diabetic foot in detail, and ends with protections for high-risk feet and the prevention of ulcers. This manuscript covers the disciplines of internal medicine, surgical, nursing and rehabilitation and describes a total of 50 recommendations that we hope will provide procedures and protocols for clinicians dealing with diabetic foot.

Registry number: IPGRP-2020cn124

WUWHS 2020 Global Healing Changing Lives, Abu Dhabi, UAE March 8-12

The abstract book contains the abstracts of keynote lectures, global gelebration, focus sessions, symposia, regional view, workshops, sponsored symposia, oral presentations, posters and the index.

Imaging in Chronic Wound Diagnostics

Significance: Chronic wounds affect millions of patients worldwide, placing a huge burden on health care resources. Although significant progress has been made in the development of wound treatments, very few advances have been made in wound diagnosis. Recent Advances: Standard imaging methods like computed tomography, single-photon emission computed tomography, magnetic resonance imaging, terahertz imaging, and ultrasound imaging have been widely employed in wound diagnostics. A number of noninvasive optical imaging modalities like optical coherence tomography, near-infrared spectroscopy, laser Doppler imaging, spatial frequency domain imaging, digital camera imaging, and thermal and fluorescence imaging have emerged over the years. Critical Issues: While standard diagnostic wound imaging modalities provide valuable information, they cannot account for dynamic changes in the wound environment. In addition, they lack the capability to predict the healing outcome. Thus, there remains a pressing need for more efficient methods that can not only indicate the current state of the wound but also help determine whether the wound is on track to heal normally. Future Directions: Many imaging probes have been fabricated and shown to provide real-time assessment of tissue microenvironment and inflammatory responses in vivo. These probes have been demonstrated to noninvasively detect various changes in the wound environment, which include tissue pH, reactive oxygen species, fibrin deposition, matrix metalloproteinase production, and macrophage accumulation. This review summarizes the creation of these probes and their potential implications in wound monitoring.

Target region oxygenation-based endovascular treatment in a chronic limb-threatening ischemia patient with multifocal arterial diseases

Patients with chronic limb-threatening ischemia often have multiple segmental diseases requiring revascularization. However, there is no defined milestone to indicate sufficient endovascular treatment (EVT). Using multiple near-infrared spectroscopic oximeters, we intraoperatively monitored regional tissue oxygen saturation (rSO₂) to perform target region oxygenation-based EVT for a patient with chronic limb-threatening ischemia. Stent placement at the superficial femoral artery and angioplasty of the tibioperoneal trunk enabled rSO₂ in the target ischemic regions (dorsal foot and heel) to be >50% for ulcer healing. We herein describe target region oxygenation-based EVT with rSO₂ monitoring as an effective strategy for performing the minimum requisite procedures.

Poor glycemic control is associated with significant increase in major limb amputation and adverse events in the 30-day postoperative period after infrainguinal bypass

OBJECTIVE

Understanding modifiable risk factors to improve surgical outcomes is increasingly important in value-based health care. There is an established association between peripheral artery disease (PAD), diabetes, and limb loss, but less is known about expected outcomes after revascularization relative to the degree of glycemic control. The purpose of this study was to determine the association between hemoglobin A_1c (HbA_1c) management in diabetics and surgical outcomes after open infrainguinal bypass.

METHODS

The Vascular Quality Initiative infrainguinal bypass module was used to identify adult patients (≥18 years) with a history of diabetes who underwent bypass for PAD between 2011 and 2018. Exclusion criteria included missing or illogical HbA_1c values and if the indication for the limb treated was not PAD. Patients were categorized by preoperative HbA_1c levels as low severity/controlled (<7.0%), high severity (7.0%-10.0%), and very high severity (>10.0%). Primary outcomes were 30-day incidence of major adverse cardiac events (MACEs), major adverse limb events (MALEs), ipsilateral amputation, and 1-year all-cause mortality. Thirty-day outcomes were calculated using multivariable regression to compute odds ratios; hazard ratios were calculated for all-cause mortality. All analyses were adjusted for demographics, comorbidities, and clinical characteristics.

RESULTS

The final sample included 30,813 operations (27,988 unique patients): 17,517 (57%) nondiabetic patients, 5194 patients with low-severity/controlled diabetes, and 8102 (26%) patients with poorly controlled diabetes, including 5531 (70%) treated with insulin. There were 6439 (21%) patients with high-severity HbA_1c values and 1663 (5%) patients with very-high-severity HbA_1c values. Those with a very high HbA_1c level were more likely to be nonwhite, insulin dependent, and active smokers. Compared with nondiabetics, patients with very-high-severity HbA_1c had an 81% increase in MACEs and 31% increase in MALEs, whereas patients with high-severity HbA_1c only had a 49% increase in MACEs and a 12% increase in MALEs. Each one-step increase in severity category (eg, low to high to very high) was associated with an average 29% increase in the odds of MACEs and an 8% increase in the odds of MALEs.

CONCLUSIONS

Uncontrolled diabetes with an HbA_1c value >10.0% was associated with significantly worse 30-day surgical outcomes. Patients with incrementally better glycemic control (HbA_1c level of 7.0%-10.0%) did not suffer the same rate of complications, suggesting that preoperative attempts at improving diabetes management even slightly could lead to improved surgical outcomes in open infrainguinal bypass patients.

Optimizing Results in Diabetic Charcot Reconstruction

Reconstruction of the diabetic Charcot foot can be a challenge even for the most experienced foot and ankle surgeon. The first portion of this article discusses the preoperative evaluation with an emphasis on factors that can be modified before surgical reconstruction to help optimize surgical results. The second portion of the article focuses on intraoperative methods and techniques to help improve postoperative outcomes. Surgeons should strive to provide high-quality, cost-effective care by optimizing patient selection and perioperative care. Objective measures of patient outcomes will become increasingly important with the transition from volume-based to value-based care.

Long-Term In Vivo Oxygen Sensors for Peripheral Artery Disease Monitoring

Tracking of tissue oxygenation around chronic foot wounds may help direct therapy decisions in patients with peripheral artery disease (PAD). Novel sensing technology to enable such monitoring was tested over 9 months in a Sinclair mini-pig model. No adverse events were observed over the entire study period. Systemic and acute hypoxia challenges were detected during each measurement period by the microsensors. The median time to locate the sensor signal was 13 s. Lumee Oxygen microsensors appear safe for long-term repeated oxygen measurements over 9 months.

Pulse Oximetry as a Screening Test for Hemodynamically Significant Lower Extremity Peripheral Artery Disease in Adults with Type 2 Diabetes Mellitus

Objective

The main objective is to determine if digital pulse oximetry is an acceptable screening tool to detect hemodynamically significant lower extremity peripheral artery disease (PAD) in patients 50 years old and above with type 2 diabetes mellitus (T2DM) seen at the University of Santo Tomas Hospital (USTH).

Methodology

A total of 78 subjects (155 limbs) were included. Using duplex ultrasonography as the reference standard for the presence of hemodynamically significant lower extremity PAD, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were obtained for abnormal percent oxygen saturation (SpO₂) gradients and for ankle-brachial index (ABI).

Results

Of the 155 limbs, 38.7% had hemodynamically significant stenosis. Pulse oximetry had 76.7% sensitivity (95% CI, 65.2% to 88.1%), 85.3% specificity (95% CI, 78.0% to 92.6%), 76.7% PPV (95% CI, 66.5% to 84.4%) and 85.3% NPV (95% CI, 78.4% to 90.2%). ABI had 40.7% sensitivity (95% CI, 30.1% to 51.3%), 88.2% specificity (95% CI, 80.0% to 96.3%), 68.6% PPV (95% CI, 53.6% to 80.4%) and 70.1% NPV (95% CI, 65.1% to 74.5%). Combining both produces 88.1% sensitivity (95% CI, 78.5% to 97.8%), 74.2% specificity (95% CI, 65-83.4%), 68.4 PPV (95% CI, 60.3% to 75.6%) and 90.8% NPV (95% CI, 83.0% to 95.2%).

Conclusion

The results of this study suggest that pulse oximetry has a higher sensitivity than ABI as a screening tool for hemodynamically significant lower extremity PAD in T2DM patients 50 years old and above. Combining these two tests may be done to achieve a higher sensitivity.

Skin perfusion pressure as a predictor of ischemic wound healing potential

Skin perfusion pressure (SPP) is the blood pressure that is the requisite for the restoration of microcirculatory or capillary flow following controlled occlusion and subsequent flow return. The purpose of the current review was to evaluate the value of SPP for the prediction of wound healing in patients with limb ischemia. Articles published up to January 31, 2017 were searched in the PubMed database and Chinese database CNKI, using the keywords of 'skin perfusion pressure', 'limb ischemia' and 'wound healing'. Articles were obtained and reviewed to analyze the predictive value of SPP with regard to the healing potential of ischemia wounds on limbs. Three different types of techniques are currently used for the measurement of SPP, namely radioisotope clearance, photoplethysmography and laser Doppler, with laser Doppler as the most widely applied technique, due to its noninvasiveness and ease of operability. SPP may effectively assess wound healing potential in ischemic limbs with high sensitivity and specificity; however, its optimum cut-off point remains uncertain. Compared with other noninvasive microcirculatory assessment tools including ankle-brachial index, toe blood pressure and transcutaneous oxygen pressure, SPP has its advantages including that it is not affected by vascular calcification, anatomical structure or patient condition. In conclusion, SPP may be used as an index to accurately predict wound healing in patients with limb ischemia. However, it is difficult to determine the optimum cut-off of SPP due to the limitations of current data. Further study is necessary to confirm the optimum cut-off value of SPP in predicting wound healing potential.

The accuracy of an oscillometric ankle-brachial index in the diagnosis of lower limb peripheral arterial disease: A systematic review and meta-analysis

INTRODUCTION

Peripheral arterial disease (PAD) remains underdiagnosed and undertreated, partly because of limitations in the Doppler ankle-brachial index (ABI), the non-invasive gold standard.

OBJECTIVE

This systematic review and meta-analysis aims to compare the diagnostic accuracy of the oscillometric ABI and the Doppler ABI, and to examine the influence of two approaches to analysis: legs vs subjects and inclusion of oscillometric errors as PAD equivalents vs exclusion.

METHODS

Systematic searches in EMBASE, MEDLINE, Web of Science and the Cochrane Library databases were performed, from inception to February 2017. Random-effects models were computed with the Moses-Littenberg constant. Hierarchical summary receiver operating characteristic curves (HSROC) were used to summarise the overall test performance.

RESULTS

Twenty studies (1263 subjects and 3695 legs) were included in the meta-analysis. The pooled diagnostic odds ratio (dOR) for the oscillometric ABI was 32.49 (95% CI: 19.6-53.8), with 65% sensitivity (95% CI: 57-74) and 96% specificity (95%CI: 93-99). In the subgroup analysis, the "per subjects" group showed a better performance than the "per legs" group (dOR 36.44 vs 29.03). Similarly, an analysis considering oscillometric errors as PAD equivalents improved diagnostic performance (dOR 31.48 vs 28.29). The time needed for the oscillometric ABI was significantly shorter than that required for the Doppler ABI (5.90 vs 10.06 minutes, respectively).

CONCLUSIONS AND RELEVANCE

The oscillometric ABI showed an acceptable diagnostic accuracy and feasibility, potentially making it a useful tool for PAD diagnosis. We recommend considering oscillometric errors as PAD equivalents, and a "per subject" instead of a "per leg" approach, in order to improve sensitivity. Borderline oscillometric ABI values in diabetic population should raise concern of PAD.

Vascular assessment of wound healing: a clinical review

Although macrovascular screening of patients with chronic wounds, particularly in the lower extremities, is accepted as part of clinical practice guidelines, microvascular investigation is less commonly used for a variety of reasons. This can be an issue because most patients with macrovascular disease also develop concomitant microvascular dysfunction. Part of the reason for less comprehensive microvascular screening has been the lack of suitable imaging techniques that can quantify microvascular dysfunction in connection with non-healing chronic wounds. This is changing with the introduction of fluorescence microangiography. The objective of this review is to examine macro- and microvascular disease, the strengths and limitations of the approaches used and to highlight the importance of microvascular angiography in the context of wound healing.

A Toe Flexion NIRS assisted Test for Rapid Assessment of Foot Perfusion in Peripheral Arterial Disease: Feasibility, Validity, and Diagnostic Accuracy

OBJECTIVES

Feasibility, validity, and diagnostic accuracy of a non-invasive dynamic ambulatory test were assessed with near infrared spectroscopy (NIRS) evaluating foot perfusion in peripheral arterial disease (PAD).

METHODS

This was a prospective observational study. Eighty PAD patients (63 males, 71 ± 9 years), including 41 patients with coexisting diabetes, participated. Thirteen healthy subjects (8 males, 26 ± 8 years) were also studied by echo colour Doppler providing 160 diseased and 26 non-diseased limbs. Under identical clinostatic conditions, participants performed a 10-repetition toe flexion tests with NIRS probes on the dorsum of each foot; the area under the curve of the oxygenated haemoglobin trace ("toflex area") was calculated and the ankle-brachial index (ABI) was measured. Time of execution, rate of wrong tests, and adverse reactions were recorded. Within session reliability was assessed by administering the test twice, with a 5 minute interval between tests. The validity was assessed determining whether the toflex area was (a) dependent on the oxygen delivery from the lower limb arteries simulating PAD conditions by a progressive blood flow restriction (40-120% of systolic pressure) in healthy subjects; (b) consistent with the degree of PAD ranked by ABI and correlated with ABI and ankle pressure values in PAD patients. The diagnostic accuracy in detecting PAD was compared with examination using echo colour Doppler ultrasound.

RESULTS

All tests were rapidly, satisfactorily (<1% mistakes), and safely performed. Toflex area values, superimposable in the two sessions (intra-class correlation coefficient 0.92), were comparable to PAD values following blood flow restriction, consistent with PAD severity, correlated with dorsal pedis artery pressure (r = .21; p = .007) and ABI (r = .65; p < .001) in PAD, but not in the presence of diabetes. Toflex area was similar to echo colour Doppler for detecting PAD following receiver operating characteristic curve analysis (area = 0.987, p < .001; toflex area values ≤ -28 arbitrary units, sensitivity/specificity 95.6/100).

CONCLUSION

The toe flexion test enables ambulatory assessment of foot perfusion and PAD detection, even in the presence of non-measurable ABI or diseases affecting the microcirculation.

Novel assessment tool based on laser speckle contrast imaging to diagnose severe ischemia in the lower limb for patients with peripheral arterial disease

Objective

We propose a new assessment tool to diagnose severe ischemia of the lower limb in peripheral arterial disease, using laser speckle contrast imaging to evaluate heating‐induced microcirculatory fluctuations in the proximal and distal sites of the dorsal foot.

Study Design

A cross‐sectional study.

Methods

We recorded the slope describing the behavior of perfusion values (decrease or plateau) following the initial, heating‐induced increase in perfusion in 63 feet of patients with clinical signs of peripheral arterial disease.

Results

The plateau and decrease groups were defined as having perfusion slopes of <0.20 and ≥0.20 PU/min, respectively. Transcutaneous oxygen tension was significantly lower (P < 0.001) in the plateau than in the decrease group (8 vs. 45 mmHg), indicating more severe ischemia. The laser speckle contrast imaging thermal load test discriminated transcutaneous oxygen tension <30 mmHg with good sensitivity (78.7%) and specificity (96.2%), and an area under the curve of 0.908.

Conclusions

Both transcutaneous oxygen tension and the laser speckle contrast imaging thermal load test are useful in diagnosing severe ischemia in the foot. Lasers Surg. Med. 49:645–651, 2017. © 2017. The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Influence of wound scores and microbiology on the outcome of the diabetic foot syndrome

AIMS

To establish if the microbiology and the TEXAS, PEDIS and Wagner wound classifications of the diabetic foot syndrome (DFS) predict amputation.

METHODS

Prospective cohort study of 250 patients with DFS from 2009 to 2013. Tissue samples for culture were obtained and wound classification scores were recorded at admission.

RESULTS

Infection was monomicrobial in 131 patients (52%). Staphylococcus aureus was the most frequent pathogen (76 patients, 30%); being methicillin-resistant S. aureus in 26% (20/76) Escherichia coli and Enterobacter faecalis were 2nd and 3rd most frequent pathogens. Two hundred nine patients (85%) needed amputation being major in 25 patients (10%). The three wound scales associated minor amputation but did not predict this outcome. Predictors of minor amputation in the multivariate analysis were the presence of osteomyelitis, the location of the wound in the forefoot and of major amputation elevated C reactive proteine (CRP) levels. A low ankle-brachial index (ABI) predicted major amputation in the follow-up. Overall, 74% of gram-positives were sensitive to quinolones and 98% to vancomycin and 90% of gram-negatives to cefotaxime and 95% to carbapenems.

CONCLUSIONS

The presence of osteomyelitis and the location of the wound in the forefoot predict minor amputation and elevated CRP levels predict major amputation. In the follow-up a low ABI predicts major amputation.

Perioperative Glycemic Control and the Effect on Surgical Site Infections in Diabetic Patients Undergoing Foot and Ankle Surgery

INTRODUCTION

Diabetes mellitus is one of the leading causes of hyperglycemia in the perioperative setting. Hyperglycemia has been shown to cause increased risk of surgical site infections (SSIs) in multiple surgical specialties, but to our knowledge it has not been investigated for orthopaedic foot and ankle surgery. The aim of this study was to determine if hyperglycemia increased the rate of SSI in elective, diabetic patients that required perioperative hospitalization.

METHODS

A total of 348 consecutive inpatients after foot and ankle surgery were retrospectively evaluated. Patients who had a random serum glucose ≥200 mg/dL during the admission (Group 1) were compared to patients whose serum glucose never exceeded 200 mg/dL (Group 2).

RESULTS

Our 2 groups were similar with regard to age, gender, and body mass index. Twenty-one of 176 patients (11.9%) whose serum glucose was ≥200 mg/dL during the admission developed an SSI as compared to 9 of 172 patients (5.2%) whose serum glucose remained <200 mg/dL (odds ratio = 2.45; 95% confidence interval = 1.09-5.52;, P = .03).

DISCUSSION

Perioperative hyperglycemia ≥200 mg/dL is associated with increased rates of SSI after foot and ankle surgery. Communication with medical consultants is paramount in an effort to improve perioperative glycemic management and reduce the rate of SSI.

LEVELS OF EVIDENCE

Prognostic, Level III: Case Control.

Noninvasive Arterial Testing in Patients With Diabetes: A Guide for Foot and Ankle Surgeons

BACKGROUND

This study was designed to compare the findings of noninvasive arterial testing in patients with and without diabetic foot pathology.

METHODS

The ABI (ankle brachial index), TBI (toe brachial index), and great toe pressures were measured in 207 patients. PAD (peripheral artery disease) was defined as an ABI < 0.91 on either extremity or a TBI < 0.7.

RESULTS

PAD was identified in 103 of the 207 patients (49.8%), 80 patients with diabetic foot pathology and 23 patients with nondiabetic foot pathology. Although patients with diabetic foot pathology were 1.4 times more likely to have PAD compared to patients without diabetic pathology, this increased risk was not statistically significant (OR 1.41 [95% CI 0.75-2.64], P = .28). Patients with PAD and diabetic foot pathology were 4.9 times more likely to have ischemia (toe pressure < 60 mm Hg) than patients with PAD and nondiabetic foot pathology (OR 4.93 [95% CI 1.35-17.94], P < .05). Patients on dialysis had a 7.3 times increased likelihood of having PAD compared to patients not on dialysis (OR 7.3 [95% CI 1.6-33.6], P < .01). Patients with absent pedal pulses were 4.9 more likely to have PAD than patients with normal pulses (OR 4.9 [95% CI 2.6-9.4], P < .0001). PAD was identified in 97 of 188 patients (51.6%) with peripheral neuropathy compared to 6 of 19 patients (31.5%) without peripheral neuropathy (OR 2.31 [95% CI 0.84-6.33], P = .10).

CONCLUSIONS

Combining the ABI with TBI improved the ability to diagnose PAD in diabetic patients because the ABI has high specificity (low false positives) and the TBI has high sensitivity (low false negatives). The TBI was more reliable in patients with noncompressible arteries, medial artery calcinosis and/or neuropathy. Due to the relative incompressibility of calcified distal arteries in patients with DM, the ABI may be within normal limits in patients with PAD. This false negative result may lead surgeons to assume that normal perfusion is present.

Noninvasive imaging technologies for cutaneous wound assessment: A review

The ability to phenotype wounds for the purposes of assessing severity, healing potential and treatment is an important function of evidence-based medicine. A variety of optical technologies are currently in development for noninvasive wound assessment. To varying extents, these optical technologies have the potential to supplement traditional clinical wound evaluation and research, by providing detailed information regarding skin components imperceptible to visual inspection. These assessments are achieved through quantitative optical analysis of tissue characteristics including blood flow, collagen remodeling, hemoglobin content, inflammation, temperature, vascular structure, and water content. Technologies that have, to this date, been applied to wound assessment include: near infrared imaging, thermal imaging, optical coherence tomography, orthogonal polarization spectral imaging, fluorescence imaging, laser Doppler imaging, microscopy, spatial frequency domain imaging, photoacoustic detection, and spectral/hyperspectral imaging. We present a review of the technologies in use or development for these purposes with three aims: (1) providing basic explanations of imaging technology concepts, (2) reviewing the wound imaging literature, and (3) providing insight into areas for further application and exploration. Noninvasive imaging is a promising advancement in wound assessment and all technologies require further validation.

Arterial Plaques in Peripheral Arteries Diagnosed by Ultrasound in a Cohort of Patients With Type 2 Diabetes Mellitus

Macroangiopathy (eg, peripheral arterial disease) diagnosis in type 2 diabetes mellitus (T2DM) can be carried out by ultrasound. A surveillance study was performed in 366 consecutive patients (166 patients with T2DM and 200 non-T2DM) aiming to evaluate the frequency of single or multiple arterial plaques (Aplqs) in lower limbs and the relationship with different factors (age, duration of T2DM, glycemic balance, DM treatment, smoking habit, and microalbuminuria). Single and multiple Aplqs, respectively, were found in 10.2% and 38.6% among the patients with T2DM. Age, male gender ( P < .0002), duration of T2DM ( P < .009), insulin therapy ( P < .03), and mediocalcinosis ( P < .001) were risk factors in patients with T2DM. In conclusion, Aplqs of lower limbs are frequent in T2DM and several factors can play a determining role. Ultrasound is a helpful diagnostic tool.

Hematopoietic stem cell injury induced by ionizing radiation

SIGNIFICANCE

Exposure to ionizing radiation (IR) as the result of nuclear accidents or terrorist attacks is a significant threat and a major medical concern. Hematopoietic stem cell (HSC) injury is the primary cause of death after accidental or intentional exposure to a moderate or high dose of IR. Protecting HSCs from IR should be a primary goal in the development of novel medical countermeasures against radiation.

RECENT ADVANCES

Significant progress has been made in our understanding of the mechanisms by which IR causes HSC damage. The mechanisms include (i) induction of HSC apoptosis via the p53-Puma pathway; (ii) promotion of HSC differentiation via the activation of the G-CSF/Stat3/BATF-dependent differentiation checkpoint; (iii) induction of HSC senescence via the ROS-p38 pathway; and (iv) damage to the HSC niche.

CRITICAL ISSUES

Induction of apoptosis in HSCs and hematopoietic progenitor cells is primarily responsible for IR-induced acute bone marrow (BM) injury. Long-term BM suppression caused by IR is mainly attributable to the induction of HSC senescence. However, the promotion of HSC differentiation and damage to the HSC niche can contribute to both the acute and long-term effects of IR on the hematopoietic system.

FUTURE DIRECTIONS

In this review, we have summarized a number of recent findings that provide new insights into the mechanisms whereby IR damages HSCs. These findings will provide new opportunities for developing a mechanism-based strategy to prevent and/or mitigate IR-induced BM suppression. Antioxid.

Patterns of disease distribution of lower extremity peripheral arterial disease

Peripheral arterial disease (PAD) is a common manifestation of atherosclerosis that is associated with an increased risk of mortality and cardiovascular (CV) events. Peripheral arterial disease involves the arteries distal to the aortic bifurcation in a nonuniform manner. Studies have shown that symptoms and prognosis of patients with PAD vary according to the location and size of the affected artery. Several modalities have been used to identify the location of PAD, including noninvasive evaluations and invasive procedures. Peripheral arterial disease has a risk factor profile similar to that associated with coronary artery disease (ie, age, gender, diabetes, smoking, hypertension, and hyperlipidemia). Many studies have shown that the distribution, extent, and progression of PAD are influenced by CV risk factors but the findings are not consistent. Management strategies for PAD are different for proximal and distal PAD. The objective of this review is to discuss the patterns of diseases distribution in patients with PAD.

Functional MRI in peripheral arterial disease: arterial peak flow versus ankle-brachial index

Objectives

The purpose of this study was to compare the success rate of successful arterial peak flow (APF) and ankle-brachial index (ABI) measurements in patients with suspected or known peripheral arterial disease (PAD).

Materials and Methods

183 patients with varying degrees of PAD were included. All subjects underwent ABI measurements and MR imaging of the popliteal artery to determine APF. Proportions of patients with successful APF and ABI measurements were compared and the discriminative capability was evaluated.

Results

APF was successfully measured in 91% of the patients, whereas the ABI could be determined in 71% of the patients (p<0.01). Success rates of APF and ABI were significantly higher in patients with intermittent claudication (95% and 80%, respectively) than in patients with critical ischemia (87% and 62%, respectively).

Conclusions

Compared to the assessment of PAD severity with ABI, the success rate of MRI-based APF measurements in patients with a clinical indication for MRA is 20% higher, with similar discriminatory capacity for disease severity. Therefore, APF is an especially convenient and valuable measure to assess severity in PAD patients scheduled to undergo MR angiography to obtain additional functional information concerning the vascular status.

Peripheral arterial disease and bypass surgery in the diabetic lower limb

PAD is very common in people with diabetes and is one of the strongest predictors of developing nonhealing foot ulcers and suffering amputation. There is strong evidence to show that early detection of PAD and revascularization will reduce amputations. Despite this, many patients have no vascular assessment even when they present with a foot ulcer or before amputation. Even when identified, patients are referred late, which worsens their outcome. Currently there is no evidence to support surgical revascularization over endovascular treatments, but in reality the techniques are complementary and the choice of revascularization procedure should be determined by an experienced multidisciplinary vascular team. Surgical revascularization can achieve good results but careful patient selection, operative planning, and the use of autologous vein are necessary. What is clearly apparent is that at present not enough patients are being offered revascularization to prevent amputation.

Transcutaneous oxygen tension as a potential predictor of cardiovascular events in type 2 diabetes: comparison with ankle-brachial index

OBJECTIVE

Transcutaneous oxygen tension (TcPO2) measures tissue perfusion and is important in the management of peripheral artery disease (PAD). Ankle brachial index (ABI) is used for the diagnosis of PAD and represents a predictor of major adverse cardiovascular events (MACE), even if in diabetes its diagnostic and predictive value seems to be reduced. No study has evaluated TcPO2 as a predictor of cardiovascular events. Aim of this longitudinal study was to assess whether TcPO2 is better than ABI at predicting MACE in type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

Among 361 consecutive patients with apparently uncomplicated diabetes, 67 MACE occurred during a follow-up period of 45.8 ± 23.2 months.

RESULTS

The percentage of both subjects with low ABI (≤ 0.9) and subjects with low TcPO2 (≤ 46 mmHg as measured by a receiver operating characteristic curve) was significantly (<0.001) greater among patients with than among those without MACEs (ABI 64.2 vs. 40.8; TcPO2 58.2 vs. 34%). The Kaplan-Meier method showed that both low ABI (Mantel log-rank test, 4.087; P = 0.043) and low TcPO2 (Mantel log-rank test, 33.748; P > 0.0001) were associated with a higher rate of MACEs. Cox regression analysis showed that low TcPO2 (hazard ratio 1.78 [95% CI 1.44-2.23]; P < 0.001) was a significant predictor of MACE, while ABI did not enter the model.

CONCLUSIONS

This longitudinal study showed that TcPO2 may be a potential predictor of MACE among patients with uncomplicated type 2 diabetes and that its predictive value seems to be greater than that of ABI.

Heat-washout - an objective method for diagnosing neuropathy and atherosclerosis in diabetic patients

BACKGROUND

The heat-washout method is an objective method that measures cutaneous blood flow rate (BFR) in ml (100 g. min)(-1), previously found useful for measuring toe BFR in non-diabetic patients with claudication.

AIM

The method is used for evaluating the presence of a veno-arteriolar reflex (VAR) in the forefoot and signs of atherosclerosis in the first toe in type 2 diabetics.

METHODS

Nine type 2 diabetics for +10 years, peripheral neuropathy, median age 62, and 9 healthy subjects without diabetes, median age 52 were examined for the presence of a VAR in the forefoot. A VAR was present when BFR decreased 25% or more with the foot 50 cm below heart level. Examinations for atherosclerosis were made in the pulp of the first toe. An increase in BFR of 50% or more with the foot 50 cm below heart level indicated the presence of atherosclerosis.

RESULTS

The VAR was significantly attenuated in type 2 diabetics with neuropathy compared to controls, (P<0·01). Only one patient with known neuropathy and diabetes showed a reflex compared to eight out of nine controls (P<0·01). The VAR was correlated to the vibration perception threshold measured with biothesiometry (r = -0·661, P = 0·0003). Two patients with type 2 diabetes and neuropathy without clinical sign of peripheral artery disease (PAD) had an abnormal response similar to that seen in subjects with intermittent claudication.

CONCLUSION

The heat-washout method seems useful as and objective method for evaluating as well the presence of a VAR as atherosclerosis in type 2 diabetics.

PET/SPECT imaging of hindlimb ischemia: focusing on angiogenesis and blood flow

Peripheral artery disease (PAD) is a result of the atherosclerotic narrowing of blood vessels to the extremities, and the subsequent tissue ischemia can lead to the up-regulation of angiogenic growth factors and formation of new vessels as a recovery mechanism. Such formation of new vessels can be evaluated with various non-invasive molecular imaging techniques, where serial images from the same subjects can be obtained to allow the documentation of disease progression and therapeutic response. The most commonly used animal model for preclinical studies of PAD is the murine hindlimb ischemia model, and a number of radiotracers have been investigated for positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging of PAD. In this review article, we summarize the PET/SPECT tracers that have been tested in the murine hindlimb ischemia model as well as those used clinically to assess the extremity blood flow.

Vascular Laboratory for Critical Limb Ischaemia

This is a narrative review on vascular assessment for critical limb ischaemia in the past and present combining Finnish and Japanese experience.

Safety and efficacy of mild compression (18-25 mm Hg) therapy in patients with diabetes and lower extremity edema

BACKGROUND

Patients with diabetes often present with lower extremity (LE) edema; however, because of concomitant peripheral arterial disease, compression therapy is generally avoided by providers in fear of compromising arterial circulation. This pilot study sought to assess whether diabetic socks with mild compression (18-25 mm Hg) can reduce LE edema in patients with diabetes without negatively impacting vascularity.

METHODS

Eighteen subjects (9 males, 9 females) aged 61 ± 11 years with diabetes, LE edema, and a mean ankle-brachial index (ABI) of 1.10 ± 0.21 successfully completed this uncontrolled study. At baseline, subjects were fitted and instructed to wear the socks during all waking hours. Follow-up visits occurred weekly for four consecutive weeks. Edema was quantified through midfoot, ankle, and calf circumferences and cutaneous fluid measurements. Vascular status was tracked via ABI.

RESULTS

Repeated measures analysis of variance and least significant difference post hoc analyses were used for data analyses. Calf circumferences showed a statistically significant (p < .05) decrease of 1.3 ± 0.28 cm after just one week and remained significantly smaller than baseline throughout the study. Foot circumferences were significantly reduced at week 2 (-0.98 ± 0.35 cm) and remained significantly below baseline for the remainder of the study. The ankle also demonstrated a trend of circumference reduction but was not statistically significant. Cutaneous edema significantly reduced by week 3 (-3.1 ± 1.3 U) and remained so at week 4. Ankle-brachial index significantly increased (0.14 ± 0.049) at week 2 but was not significantly higher at weeks 3 or 4. No adverse events occurred during the study.

CONCLUSIONS

Mild compression therapy (18-25 mm Hg) decreased swelling in diabetes patients with LE edema without compromising vascularity.

Chapter II: Diagnostic methods

Non-invasive vascular studies can provide crucial information on the presence, location, and severity of critical limb ischaemia (CLI), as well as the initial assessment or treatment planning. Ankle-brachial index with Doppler ultrasound, despite limitations in diabetic and end-stage renal failure patients, is the first-line evaluation of CLI. In this group of patients, toe-brachial index measurement may better establish the diagnosis. Other non-invasive measurements, such as segmental limb pressure, continuous-wave Doppler analysis and pulse volume recording, are of limited accuracy. Transcutaneous oxygen pressure (TcPO(2)) measurement may be of value when rest pain and ulcerations of the foot are present. Duplex ultrasound is the most important non-invasive tool in CLI patients combining haemodynamic evaluation with imaging modality. Computed tomography angiography (CTA) and magnetic resonance angiography (MRA) are the next imaging studies in the algorithm for CLI. Both CTA and MRA have been proven effective in aiding the decision-making of clinicians and accurate planning of intervention. The data acquired with CTA and MRA can be manipulated in a multiplanar and 3D fashion and can offer exquisite detail. CTA results are generally equivalent to MRA, and both compare favourably with contrast angiography. The individual use of different imaging modalities depends on local availability, experience, and costs. Contrast angiography represents the gold standard, provides detailed information about arterial anatomy, and is recommended when revascularisation is needed.

Evaluation of hyperspectral technology for assessing the presence and severity of peripheral artery disease

BACKGROUND

Hyperspectral imaging is a novel technology that can noninvasively measure oxyhemoglobin and deoxyhemoglobin concentrations to create an anatomic oxygenation map. It has predicted healing of diabetic foot ulcers; however, its ability to assess peripheral arterial disease (PAD) has not been studied. The aims of this study were to determine if hyperspectral imaging could accurately assess the presence or absence of PAD and accurately predict PAD severity.

METHODS

This prospective study included consecutive consenting patients presenting to the vascular laboratory at the Jesse Brown VA Medical Center during a 10-week period for a lower extremity arterial study, including ankle-brachial index (ABI) and Doppler waveforms. Patients with lower extremity edema were excluded. Patients underwent hyperspectral imaging at nine angiosomes on each extremity. Additional sites were imaged when tissue loss was present. Medical records of enrolled patients were reviewed for demographic data, active medications, surgical history, and other information pertinent to PAD. Patients were separated into no-PAD and PAD groups. Differences in hyperspectral values between the groups were evaluated using the two-tailed t test. Analysis for differences in values over varying severities of PAD, as defined by triphasic, biphasic, or monophasic Doppler waveforms, was conducted using one-way analysis of variance. Hyperspectral values were correlated with the ABI using a Pearson bivariate linear correlation test.

RESULTS

The study enrolled 126 patients (252 limbs). After exclusion of 15 patients, 111 patients were left for analysis, including 46 (92 limbs) no-PAD patients and 65 (130 limbs) PAD patients. Groups differed in age, diabetes, coronary artery disease, congestive heart failure, tobacco use, and insulin use. Deoxyhemoglobin values for the plantar metatarsal, arch, and heel angiosomes were significantly different between patients with and without PAD (P < .005). Mean deoxyhemoglobin values for the same three angiosomes showed significant differences between patients with monophasic, biphasic, and triphasic waveforms (P < .05). In patients with PAD, there was also significant correlation between deoxyhemoglobin values and ABI for the same three angiosomes (P = .001). Oxyhemoglobin values did not predict the presence or absence of PAD, did not correlate with PAD severity, and did not correlate with the ABI.

CONCLUSIONS

These results suggest the ability of hyperspectral imaging to detect the presence of PAD. Hyperspectral measurements can also evaluate different severities of PAD.