Prediction of amputation wound healing with skin perfusion pressure

Skin injury: Associations with variables related to perfusion and pressure

Skin injuries are a major healthcare problem that are not well understood or prevented in the critically ill, suggesting that underappreciated variables are contributing. This pilot study tested the hypothesis that perfusion-related factors contribute to skin injuries diagnosed as hospital-acquired pressure injuries (HAPIs). A total of 533 adult patients were followed over 2574 critical care days (mean age 62.4, standard deviation (SD) 14.3 years, mean body mass index 30.4 (SD 7.4) kg/m2, 36.4% female). This was a secondary analysis of prospective, non-randomised clinical data from an intensive care unit at a large urban teaching hospital. Factors related to perfusion, specifically two or more infusions of vasopressors/inotropes, temporary mechanical circulatory support (MCS), extracorporeal membrane oxygenation, and durable MCS, were analysed to determine whether they were more strongly associated with HAPIs than immobility due to prolonged mechanical ventilation (>72 h) or operating room time (>6 h). Patients diagnosed with a HAPI had a statistically significant higher risk of being exposed to variables related to perfusion and immobility (P < 0.05 for each variable). Perfusion-related variables, except durable MCS, had a larger effect on skin breakdown (number needed to harm (NNH) 4-10) than immobility-associated variables (NNH 12-17). The finding that perfusion-related variables predicted HAPIs may warrant consideration of alternative diagnoses, such as skin failure due to impaired perfusion as a pathophysiological process that occurs concurrently with multisystem organ failure. Differentiation of skin injuries primarily from circulatory malfunction, rather than external pressure, may guide the development of more effective treatment and prevention protocols. This pilot study suggests that the contribution of perfusion to skin injuries should be explored further.

Renin-Angiotensin-Aldosterone System (RAS) Inhibitors May Suppress the Prevalence of Peripheral Arterial Disease (PAD) in Elderly, Chronic Hemodialysis Patients

According to the hypertension guidelines, calcium antagonists are recommended as antihypertensive drugs for Stage 5 of chronic kidney disease (CKDG5) and late elderly patients, whereas renin-angiotensin-aldosterone system (RAS) inhibitors (RASi) are not recommended. We screened elderly CKDG5D patients at a single outpatient maintenance hemodialysis center for the progression of peripheral arterial disease (PAD) using the ankle-brachial index (ABI) and skin perfusion pressure (SPP) tests, as well as logistic regression analysis, to determine the association between PAD and the treatment with RASi and the association between the treatment with RASi and the need for hospitalization within one year of observation. With the presence of PAD as the explanatory variable and the presence of RASi as the objective variable, the odds ratio was 1.23 (95% confidence interval [CI] 0.37 to 3.82) in univariate analysis. After adjusting for confounding factors (age, gender, and hypertension), the odds ratio in multivariate analysis was 0.83 (95% CI 0.46 to 6.08). The presence or absence of PAD was significantly associated with an odds ratio of 3.24 (p = .04, 95% CI 1.0 to 10.25) and 4.63 (p = .026, 95% CI 1.20 to 17.84) in univariate and multivariate analyses, respectively, when the outcome was hospitalization at one year, regardless of the presence or absence of RASi. However, in univariate analysis, the odds ratio was 1.23 (95% CI 0.37 to 3.82) with RASi status as the explanatory variable and one-year hospitalization as the objective variable. After adjusting for confounders, the odds ratio in multivariate analysis was 0.83 (95% CI 0.46 to 6.08). Although further large-scale, multicenter studies are needed to establish the evidence, our results suggest that RASi treatment may have a suppressive effect on the prevalence of PAD and the need for hospitalization in elderly CKDG5 dialysis (CKDG5D) patients.

Tissue optical perfusion pressure: a simplified, more reliable, and faster assessment of pedal microcirculation in peripheral artery disease

Oscillometry is an alternative to continuous-wave Doppler (cw-Doppler) to determine peripheral artery disease (PAD) severity using the ankle-brachial index (ABI). cw-Doppler ABI differentiates systolic pressure of ATP and ADP where either one of both values in most patients is higher (high) and the other value is lower (low). In contrast, oscillometric ABI measures the strongest signal and hence misses the lower value. Both do not take pedal perfusion into consideration. Simultaneous determination of tissue microperfusion cares for pedal PAD. ABI was determined by cw-Doppler and oscillometry. Tissue optical perfusion pressure (TOPP) was taken from the first toe using photoplethysmography. 323 patients were evaluated retrospectively in 3 independent groups. group 1 (99 patients) compared TOPP and oscillometric ABI with systolic cw-Doppler-pressure and cw-Doppler ABI. In group 2 (103 patients) TOPP was compared with toe pressure (TP). In group 3 (121 symptomatic patients) TOPP and ABI at rest and after stress were compared (ultrasound examination and magnetic resonance angiography (MRA) or computer tomography angiography (CTA) as control). Bland-Altman-plot analysis presented no significant difference between oscillometric ABI and the high cw-Doppler ABI (group 1). TOPP showed a difference of 26mmHg to the low cw-Doppler-pressure and none to the high cw-Doppler-pressure. In group 2 TOPP correlates to TP but presented a difference of 37 mmHg. group 3 showed weak or no correlation between ABI and walking distance. Oscillometric ABI correlates significantly to TOPP. To conclude, data after stress present a better correlation than at rest. We conclude that TOPP provides absolute values of pedal macro-/microcirculation at rest and after stress tests.NEW & NOTEWORTHY This new application of photoplethysmography investigated the microcirculation in peripheral artery disease at the level of the toe pad and determined the tissue optical perfusion pressure as the first pulsatile signal during automatic cuff deflation at the ankle. It is the first time that this method has been integrated for simultaneous routine examination in an automatic oscillometric ankle-brachial index (ABI) system. This quick and simple measurement technique provides clinical information on the microcirculation downstream the routine ABI measurement at rest and in particular after stress test.

Vascular Assessment of the Lower Extremity with a Chronic Wound

Peripheral arterial disease (PAD) affects many individuals worldwide and is associated with increased morbidity and mortality. Controversy exists on whether or not to screen asymptomatic patients. Further complicating this is that many patients with a chronic lower extremity wound are often asymptomatic. PAD and traditional noninvasive vascular studies may be inaccurate in providing a correct diagnosis. A review of current and novel vascular assessment modalities along with their benefits and limitations are presented here. A combination of these vascular assessments may help improve accuracy in diagnosis, providing timely care to those patients in need.

Assessment of foot perfusion: Overview of modalities, review of evidence, and identification of evidence gaps

Patients with critical limb ischemia have nonhealing wounds and/or ischemic rest pain and are at high risk for amputation and mortality. Accurate evaluation of foot perfusion should help avoid unnecessary amputation, guide revascularization strategies, and offer efficient surveillance for patency. Our aim is to review current modalities of assessing foot perfusion in the context of the practical clinical management of patients with critical limb ischemia.

Below-the-Ankle Arrival Time as a Novel Limb Tissue Perfusion Index: Two-dimensional Perfusion Angiography Evaluation

Purpose: To identify lower limb 2-dimensional (2D) perfusion angiographic parameters that are related to skin perfusion pressure (SPP), a predictor of wound healing in patients with chronic limb-threatening ischemia (CLTI) undergoing below-the-knee (BTK) endovascular treatment (EVT). Materials and Methods: Thirty-three consecutive patients (mean age 74.5 years; 18 men) with 47 isolated BTK lesions in 33 limbs (Rutherford category 3–5) underwent EVT. Dorsal and plantar SPPs were measured before EVT and the day after. The indexed blood flow below the ankle was measured using 2D perfusion angiography before and after EVT to determine changes in perfusion parameters [arrival time (AT), time to peak, wash-in rate, mean transit time, and width and area under the time-density curve] at rest vs during hyperemia induced with a 20-mg intra-arterial papaverine infusion. Correlations between the 2D perfusion parameters and SPPs were assessed using the Pearson coefficient. The cutoff points to predict mean SPPs >40 mm Hg were analyzed using a receiver operating characteristic curve; outcomes are reported as the area under the curve (AUC) with 95% confidence interval (CI). Results: After EVT at rest and during hyperemia, only AT was significantly changed, although hyperemia produced significant changes in all the pre-/post-EVT 2D perfusion parameters except the wash-in rate. Dorsal and plantar SPPs after EVT were significantly increased and correlated with hyperemic AT and the AT ratio (hyperemia/at rest values) below the ankle. Hyperemic ATs <6.3 seconds and AT ratios <0.78 were predictive factors for a mean SPP >40 mm Hg, with AUCs of 0.83 (95% CI 0.67 to 0.99) and 0.78 (95% CI 0.61 to 0.95), respectively. Conclusion: Hyperemic ATs <6.3 seconds or AT ratios <0.78 below the ankle may be essential to obtain sufficient SPPs for limb salvage in BTK lesions. Thus, the use of 2D perfusion angiography enabled the monitoring of lower limb tissue perfusion throughout EVT and may thereby optimize treatment of CLTI.

Revision After Total Transmetatarsal Amputation

Total transmetatarsal amputation (TMA) can be an option for foot salvage in gangrene, sepsis, or infected necrosis. However, the literature concerning predictive outcome factors and bacterial sampling is scarce. To identify potential associations between revision surgery and underlying bacteria or other preoperative selection criteria, we reviewed all patients with TMA who were treated at our institution. We compared the patients with remissions with surgical revisions. Among 96 adult patients with TMA (105 amputations), 42 required a revision surgery (40%), 18 had a further minor proximal surgical reamputation (17%) and 18 had a major proximal surgical reamputation (14%). In group comparisons, a previous infection with Staphylococcus aureus was protective with a lower revision risk (4/26 with revision surgery vs 22/26 without revisions; p = .03). This was the opposite for postoperative persistent soft tissue or bone infections (p < .01) and delayed wound healing (p < .01), which were positively associated with a revision risk. The American Society of Anesthesiologists Score, sex, age, body mass index, diabetes, polyneuropathy, chronic renal failure, dialysis, peripheral arterial disease, smoking status, and antibiotic regimen did not influence this revision risk. These results must be interpreted cautiously because no multiple variable calculations could be conducted as a result of the paucity of cases and confounding could not be evaluated sufficiently. TMA is an option to prevent major amputations, but it may be associated with a subsequent revision risk of 40% in adult patients. In our cohort study, persistent postamputation infection and delayed wound healing were associated with revision. However, no preoperative selection criteria were found that lead to revision surgery except for an infection with Staphylococcus aureus, which protected against revision surgery.

Peripheral artery disease: the new frontiers of imaging techniques to evaluate the evolution of regenerative medicine

Introduction: Stem cells (ESC, iPSC, MSC) are known to have intrinsic regenerative properties. In the last decades numerous findings have favored the development of innovative therapeutic protocols based on the use of stem cells (Regenerative Medicine/Cell Therapy) for the treatment of numerous diseases including PAD, with promising results in preclinical studies. So far, several clinical studies have shown a general improvement of the patient's clinical outcome, however they possess many critical issues caused by the non-randomized design of the limited number of patients examined, the type cells to be used, their dosage, the short duration of treatment and also their delivery strategy. Areas covered: In this context, the use of the most advanced molecular imaging techniques will allow the visualization of very important physio-pathological processes otherwise invisible with conventional techniques, such as angiogenesis, also providing important structural and functional data. Expert opinion: The new frontier of cell therapy applied to PAD, potentially able to stop or even the process that causes the disease, with particular emphasis on the clinical aspects that different types of cells involve and on the use of more innovative molecular imaging techniques now available.

Utility of skin perfusion pressure values with the Society for Vascular Surgery Wound, Ischemia, and foot Infection classification system

OBJECTIVE

The addition of skin perfusion pressure (SPP) might enhance the predictive value of the Society for Vascular Surgery Wound, Ischemia, and foot Infection (WIfI) classification system. The purpose of the present study was to evaluate the SPP for each WIfI classification stage among patients with foot wounds by cross-referencing the results of prospectively monitored limb outcomes and to derive the SPP criteria that could be combined with other measurements to grade ischemia for the WIfI classification.

METHODS

From July 2015 to June 2017, patients with foot wounds that met the WIfI classification criteria were prospectively enrolled. We assessed the limbs using the WIfI ischemia grade without measuring the transcutaneous oxygen pressure but measured the SPP. After monitoring for 1 year, the predictability of the WIfI stages was analyzed according to whether the limbs had not healed (unchanged or worsened wounds, minor or major amputation, all-cause death) or had healed (improved or healed wounds) by comparing stages 1 and 2 with stages 3 and 4. We also statistically analyzed the SPP values that could be the boundary values between each ischemia grade and reevaluated the predictability of the WIfI stages with the boundary SPP values.

RESULTS

We enrolled a total of 91 limbs for 76 patients (mean age, 70.5 ± 12.0 years). The mean SPP values stratified by ischemia grade 0 to 3 were 52.1, 41.1, 27.1, and 18.8 mm Hg, respectively (an SPP of <30 mm Hg indicates severe ischemia). After monitoring for 1 year, 19 of 48 limbs in stage 1 and 2 and 35 of 43 in stage 3 and 4 were in the nonhealed group and 29 limbs in stage 1 and 2 and 8 limbs in stage 3 and 4 were in the healed group. The SPP boundary values between each ischemia (I) grade were calculated as 45 mm Hg for I-0/I-1, 35 for I-1/I-2, and 25 for I-2/I-3. When jointly using the boundary SPP values, the ischemia grade changed for 23 limbs, altering the distribution of the WIfI stages and limb outcomes: 11 of 38 limbs in stage 1 and 2 and 43 of 53 in stage 3 and 4 were transferred to the nonhealed group. The sensitivity, efficiency, and negative predictive value of WIfI staging improved when staging with SPP: from 65% to 80%, 70% to 77%, and 60% to 71%, respectively.

CONCLUSIONS

The SPP boundary values that could be used with ischemia grade in the WIfI classification were identified as 45, 35, and 25 mm Hg. The addition of SPP could improve the accuracy of the evaluation.

Skin Perfusion Pressure and Wound Closure Time in Lower Extremity Wounds

Introduction

Peripheral Arterial Disease (PAD) affects approximately 8 million patients in the United States. We investigate the relationship of Skin Perfusion Pressure (SPP) and wound closure time in lower extremity wounds.

Methods

We conducted a retrospective study of 1125 lower extremity wounds in 998 patients between June 2006 and October 2014 in our wound clinic. We analyzed the relationship between SPPand wound closure time. SPP was measured using a Laser Doppler instrument.

Results

Patients with SPP values over 30 mmHg had shorter wound closure times, while patients with SPP values below 30 mmHg had a significantly longer wound closure time. Diabetic patients took longer to achieve wound closure compared to non-diabetics. No significant relationship was observed between SPP and wound closure time in relation to age or gender.

Conclusion

SPP is a useful tool in estimating time to wound closure and assessing the necessity of vascular interventions in lower extremity wounds.

Skin perfusion pressure for the prediction of wound healing in critical limb ischemia: a meta-analysis

INTRODUCTION

The purpose of this meta-analysis was to determine the value and efficacy of skin perfusion pressure (SPP) for the prediction of wound healing in patients with critical limb ischemia.

MATERIAL AND METHODS

Medline, Cochrane, EMBASE, and Google Scholar databases were searched from inception until December 31, 2014 using combinations of the following keywords: skin perfusion pressure, limb ischemia, wound healing, prediction. Randomized controlled trials, 2-arm prospective studies, and retrospective studies that measured SPP in patients with limb ischemia were included. The outcome was the sensitivity and specificity of SPP for the prediction of wound healing.

RESULTS

Five studies were included in the meta-analysis. The mean patient age ranged from 62.2 to 71.5 years, and the majority were male. The pooled sensitivity of SPP for the prediction of wound healing was 79.9% using 30 mm Hg as the cut-off, 67.1% using 40 mm Hg, and 76.1% for all included studies (95% CI: 73.9-84.9%, 55.8-76.8%, and 70.7-80.8%, respectively). The pooled specificity was 78.2% using 30 mm Hg, 84.2% using 40 mm Hg, and 82.1% for all included studies (95% CI: 61.5-89.0%, 74.0-90.9%, 73.7-88.3%, respectively).

CONCLUSIONS

Skin perfusion pressure can accurately predict wound healing in patients with critical limb ischemia.

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.

Skin perfusion pressure as an indicator of tissue perfusion in valvular heart surgery: Preliminary results from a prospective, observational study

Hemodynamic management aims to provide adequate tissue perfusion, which is often altered during cardiac surgery with cardiopulmonary bypass (CPB). We evaluated whether skin perfusion pressure (SPP) can be used for monitoring of adequacy of tissue perfusion in patients undergoing valvular heart surgery. Seventy-two patients undergoing valve replacement were enrolled. SPP and serum lactate level were assessed after anaesthesia induction (baseline), during CPB, after CPB-off, end of surgery, arrival at intensive care unit, and postoperative 6 h. Lactate was further measured until postoperative 48 h. Association of SPP with lactate and 30-day morbidity comprising myocardial infarction, acute kidney injury, stroke, prolonged intubation, sternal infection, reoperation, and mortality was assessed. Among the lactate levels, postoperative 6 h peak value was most closely linked to composite of 30-day morbidity. The SPP value during CPB and its % change from the baseline value were significantly associated with the postoperative 6 h peak lactate (r = -0.26, P = 0.030 and r = 0.47, P = 0.001, respectively). Optimal cut-off of % decrease in SPP during CPB from baseline value for the postoperative 6 h hyperlactatemia was 48% (area under curve, 0.808; 95% confidence interval (CI), 0.652-0.963; P = 0.001). Decrease in SPP >48% during CPB from baseline value was associated with a 12.8-fold increased risk of composite endpoint of 30-day morbidity (95% CI, 1.48-111.42; P = 0.021) on multivariate logistic regression. Large decrease in SPP during CPB predicts postoperative 6 h hyperlactatemia and 30-day morbidity, which implicates a promising role of SPP monitoring in the achievement of optimal perfusion during CPB.

The care of transmetatarsal amputation in diabetic foot gangrene

Diabetic foot ulcerations may determine minor or major amputation, with a high impact on patients' life expectation and quality of life and on economic burden. Among minor amputations, transmetatarsal amputation (TMA) appears to be the most effective in terms of limb salvage rates and in maintaining foot and ankle biomechanics. In spite of this, TMA needs particular pre- and postoperative management in order to avoid the frequent failure rates. A systematic review was undertaken of studies concerning TMA and its care in diabetic foot gangrene. Studies were identified by searching the MEDLINE, Scopus and Science Direct databases until 13 January 2016. All studies were assessed using the Downs and Black quality checklist. Of the 348 records found, 86 matched our inclusion criteria. After reading the full-text articles, we decided to exclude 35 manuscripts because of the following reasons: (1) no innovative or important content, (2) no multivariable analysis, (3) insufficient data, (4) no clear potential biases or strategies to solve them, (5) no clear endpoints and (6) inconsistent or arbitrary conclusions. The final set included 51 articles. In the current literature, there are less data about TMA, indication for the selection of patients, outcomes and complications. Generally, the judgment of an experienced physician is one of the best indicators of subsequent healing. Ankle brachial indices, toe pressures, laser Doppler skin perfusion pressures, angiography and Doppler assessment of foot vasculature may help physicians in this decision. In any case, despite the presumed lower healing rate, it is reasonable to pursue a TMA in a patient with a higher likelihood of continued ambulation. Furthermore, tailored wound closure, adjuvant local treatments and the choice of the most appropriate antibiotic therapy, when infection occurs, are pivotal elements for the success of TMA procedures. TMA is a valuable option for diabetic foot gangrene that can prevent major limb loss and minimise loss of function, thus improving the quality of life for diabetic patients.

Skin Perfusion Pressure and the Prevalence of Atherothrombosis in Hemodialysis Patients

End-stage renal disease is associated with atherothrombosis (ATIS), which, in turn, can promote peripheral arterial occlusive disease (PAOD), coronary artery disease (CAD), and/or cerebrovascular disease (CVD). The aim of this study was to determine whether low plantar skin perfusion pressure (SPP) was related to ATIS among 122 patients receiving maintenance hemodialysis (HD) from March to November 2013 at our outpatient facility. We routinely measured SPP and used the value for analysis. In addition, we retrospectively evaluated the prevalence of ATIS with patients categorized to CAD, CVD, or PAOD groups. Of the 122 outpatients, ATIS was diagnosed in about half (N = 60, 49.2% vs. 62, 50.8%; average SPP, 56.6 vs. 72.9 mm Hg, respectively). These data show that SPP was significantly lower in patients with ATIS (difference, 16.3 mm Hg; P < 0.001) and there was a negative relationship between average SPPs and past history of ATIS complications. When the patients were stratified by the presence of diabetes mellitus, this trend was stronger. Particularly, receiver operating characteristic analysis of HD patients with diabetes revealed a cutoff point of 53.0 mm Hg and an area under the curve value of 0.84, with a sensitivity of 77.0% and specificity of 91.3%. Therefore, we concluded that SPP enables the evaluation of not only local PAOD, but also systemic ATIS. Moreover, we found that a cutoff point of 53.0 mm Hg was useful for detection of ATIS in HD patients.

REVIEW: HEMODYNAMIC STUDIES FOR LOWER LIMB AMPUTATION AND REHABILITATION

No matter what the reason and level of amputation are, amputees will face many complex postoperative problems and potential complications. From the perioperative stage to lengthy rehabilitation process, patients need comprehensive and cautious therapies to help them rebuild their physical and mental health. Although there is some scattered information, the achievements of hemodynamic study for lower limb amputation and rehabilitation have not been systematically classified and summarized. The purpose of this review is to introduce and discuss the hemodynamic issues in preoperative diagnosis, surgical techniques and postoperative problems in the past two decades. Whether from clinical or biomechanical perspective, the investigations of the former two stages have been relatively mature and gained some clear outcomes, even if some conclusions are conflicting and controversial. While in terms of the postoperative problems, such as the common pressure ulcers, DTI and muscle atrophy, there is a lack of vascular or blood flow state studies specifically for lower residual limb. Therefore, the future research focus of hemodynamics for lower limb amputation should probably be the detailed investigations on the relationships between various blood flow parameters and certain common complications. Although hemodynamic research has made some achievements at this stage, it is believed that more advanced and reliable techniques are pending for further explorations and developments.

Distal bypass to a critically ischemic foot increases the skin perfusion pressure at the opposite site of the distal anastomosis

INTRODUCTION

The purpose of the study was to reveal the effect of blood flow supply to the foot by analyzing the skin perfusion pressure values and the pedal arch connection after bypass surgery.

PATIENTS AND METHODS

We selected 48 operated limbs whose skin perfusion pressure was measured pre- and post-operatively on the opposite site of distal anastomosis. We also assigned the ischemic limbs to three groups according to the patency of the pedal arch: good, intermediate, and poor.

RESULTS

The mean value of skin perfusion pressure increased significantly from 27.0 ± 14.9 to 52.8 ± 16.0 (p < 0.001) post-operatively. Skin perfusion pressure improved in most of the limbs post-operatively and decreased or unchanged in only four limbs, all of which showed improved tissue loss. Three amputated limbs were due to infection, and all showed an increase in skin perfusion pressure.

CONCLUSION

It was difficult to correlate limb prognosis to skin perfusion pressure and the pedal arch connection.

Postprocedural Skin Perfusion Pressure Correlates With Clinical Outcomes 1 Year After Endovascular Therapy for Patients With Critical Limb Ischemia

BACKGROUND

Although skin perfusion pressure (SPP) is widely used clinically to predict probability of wound healing, correlation between clinical outcomes and SPP has not been systematically studied.

METHODS

This subanalysis of the prospective multicenter OLIVE registry of patients who received infrainguinal endovascular therapy (EVT) for critical limb ischemia (CLI) assessed the association between clinical outcomes and postoperative SPP in 211 consecutive patients. Logistic regression analysis was performed, with amputation-free survival (AFS), modified major adverse limb events (MALEs), and complete wound healing as dependent variables and postprocedural SPP as independent variable.

RESULT

Pre- and postprocedural SPP was 28 ± 11 and 46 ± 18 mm Hg, respectively. In logistic regression analysis, postprocedural SPP correlated with 1-year AFS (P = .018), modified MALEs (P < .001), and wound healing (P = .022).

CONCLUSION

Postprocedural SPP correlates with clinical outcomes after EVT for patients with CLI.

Intestinal perfusion monitoring using photoplethysmography

In abdominal trauma patients, monitoring intestinal perfusion and oxygen consumption is essential during the resuscitation period. Photoplethysmography is an optical technique potentially capable of monitoring these changes in real time to provide the medical staff with a timely and quantitative measure of the adequacy of resuscitation. The challenges for using optical techniques in monitoring hemodynamics in intestinal tissue are discussed, and the solutions to these challenges are presented using a combination of Monte Carlo modeling and theoretical analysis of light propagation in tissue. In particular, it is shown that by using visible wavelengths (i.e., 470 and 525 nm), the perfusion signal is enhanced and the background contribution is decreased compared with using traditional near-infrared wavelengths leading to an order of magnitude enhancement in the signal-to-background ratio. It was further shown that, using the visible wavelengths, similar sensitivity to oxygenation changes could be obtained (over 50% compared with that of near-infrared wavelengths). This is mainly due to the increased contrast between tissue and blood in that spectral region and the confinement of the photons to the thickness of the small intestine. Moreover, the modeling results show that the source to detector separation should be limited to roughly 6 mm while using traditional near-infrared light, with a few centimeters source to detector separation leads to poor signal-to-background ratio. Finally, a visible wavelength system is tested in an in vivo porcine study, and the possibility of monitoring intestinal perfusion changes is showed.

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.

Transmetatarsal amputation: a case series and review of the literature

Foot ulceration is a major cause of morbidity amongst patients with diabetes. In severe cases of ulceration, osteomyelitis and amputation can ensue. A distinct lack of agreement exists on the most appropriate level of amputation in cases of severe foot ulceration/infection to provide predictable healing rates. This paper provides an overview of the transmetatarsal amputation (TMA) as a limb salvage procedure and is written with the perspective and experiences of the Department of Podiatric Surgery at West Middlesex University Hospital (WMUH). We have reflected on the cases of 11 patients (12 feet) and have found the TMA to be an effective procedure in the management of cases of severe forefoot ulceration and infection.

The effectiveness of skin perfusion pressure measurements during endovascular therapy in determining the endpoint in critical limb ischemia

A 78-year-old man had right foot ulceration. The skin perfusion pressure (SPP) at the dorsum was 12 mmHg. Angiography revealed right iliac artery occlusion and diffuse stenosis of right superficial femoral artery. After stenting of the iliac arteries, the SPP was still 23 mmHg. Hence, we also inserted stents in the right superficial femoral artery. The anterior tibial artery remained stenosed, and the posterior tibial and fibular arteries were occluded. However, as the SPP had increased to 46 mmHg the treatment was discontinued. The ulcers improved. Measurement of SPP during a procedure may be useful in determining the treatment endpoint.

Skin perfusion pressure measurement to assess improvement in peripheral circulation after arterial reconstruction for critical limb ischemia

AIM

To assess the utility of skin perfusion pressure (SPP) measurement in evaluating the outcome of vascular constructions for critical limb ischemia (CLI) patients.

METHODS

We retrospectively studied 19 lower limbs in 18 patients who underwent arterial reconstruction for CLI from whom SPP measurements had been obtained pre- and postoperatively between 2008 and 2010. Six limbs whose ulcers had healed postoperatively were classified into group H, 7 limbs whose ulcers had not healed into group U, and 6 limbs without ulcers into group N. SPP values were compared among these groups.

RESULTS

The preoperative SPP values in all groups were <30 mmHg, without significant differences among the groups. The SPP values in groups H and N significantly improved after operation, and those in group U were significantly lower than those in the other groups.

CONCLUSIONS

SPP measurement before and after arterial reconstruction is useful to assess improvement in tissue circulation and to predict the likelihood of wound healing. An SPP value ≥30 mmHg was considered necessary for wound healing, supporting the findings of the few reports in the literature on the usefulness of SPP for assessing vascular reconstruction effects on ulcer wound healing.

Perfusion pressures and distal oxygenation in individuals with diabetes undergoing chronic hemodialysis

BACKGROUND

The number of diabetic patients worldwide was estimated to be approximately 285 million in 2010. Approximately 5% of all diabetic patients have foot ulcers, often preceded by neuropathy and delayed healing resulting from peripheral vascular disease which leads to increased risk of infection. Additionally, there is a concern that blood flow to the feet may be reduced in patients with diabetes, which may be further compounded by changes in lower extremity perfusion pressure during hemodialysis. Current laser Doppler technology provides the opportunity to identify changes in vascularityin a non-invasive fashion.

MATERIALS AND METHODS

A prospective, parallel-arm, comparison, pilot study was conducted. A total of 15 patients were enrolled, ten of whom had a documented history of diabetes. All patients required hemodialysis. Peripheral perfusion and oxygenation measurements were obtained before, midway and at the conclusion of three separate dialysis sessions within a 3-week interval for each subject.

RESULTS

Preliminary results indicate a significant reduction in toe pressure during and after hemodialysis in the diabetic patient group compared to the non-diabetic group. Significant differences were not found in skin perfusion measurements or in the oxygenation measurements at any time in diabetic and nondiabetic patients undergoing hemodialysis.

CONCLUSION

Preliminary results suggest hemodialysis may significantly affect pressure of the lower extremities in diabetic patients. Trends from these data indicate the need to further investigate the effect of hemodialysis on techniques used to heal wounds and ulcers in patients with diabetes.

A modified transmetatarsal amputation

The incidence of the diabetic foot is increasing worldwide. Because evidence has shown that transmetatarsal amputation is associated with fewer failures in amputations of the diabetic foot with or without peripheral arterial disease, improving its management and surgical technique is a mission for the surgeon. Conventional transmetatarsal amputation has held firm, however, for more than 150 years. With a new concept for the transmetatarsal amputation method aimed at a better outcome, we propose a modified procedure for preserving the soft tissue between the metatarsal bones (the vasculature complex with the muscles, periostea, and vessels) and applying it to the distal bone stumps. The purpose of this method is to secure a functional foot by preserving the longitudinal arch. The new method was applied to 11 patients with diabetes mellitus or peripheral arterial disease, or both. All wounds closed successfully. Of the 11 patients, 8 were still alive with no complications. Of these 8 patients, 6 were able to ambulate with a custom-made shoe and 2 used a wheelchair, just as preoperatively. Of the 3 patients who died, 1 died a natural death, 1 died of sepsis, and 1 of cerebral infarction. We believe that the modified transmetatarsal amputation that we have described in this report is a potential breakthrough in the care of patients with forefoot gangrene and may gain acceptance over time.

Complications of digital and lesser metatarsal surgery

Complications associated with digital and lesser metatarsal surgical procedures have been well documented in the literature. These complications may stem from systemic medical, structural, biologic, biomechanical, or iatrogenic causes. The surgeon must be cognizant of all potential complications, including ways to prevent them from occurring and how to manage them when they do occur. This article discusses preventative measures through the preoperative evaluation of the patient, and examines the subsets of complications that may occur after lesser ray surgery that pose a particular management challenge, as well as special complications specific to particular operative techniques.

Elastic stocking-induced foot necrosis in a patient with severe pneumonia

Elastic stockings (ES) are widely used for the prevention of venous thromboembolism. Here we report a case of foot ulcers induced by ES in patients with pneumonia and hypoxia. A 94-year-old woman was admitted for the treatment of pneumonia. The patient had been wearing an ES because of a history of deep vein thrombosis of the leg. Multiple foot ulcers occurred within 24 hours after the admission despite the absence of peripheral arterial occlusive disease. The ulcers took almost 5 months to heal. For patients with hypoxia, ES may further deteriorate local tissue hypoxia and thus should be used carefully.

Skin Perfusion Pressure is a Useful Tool for Evaluating Outcome of Ischemic Foot Ulcers with Conservative Therapy

OBJECTIVES

This study intended to confirm whether skin perfusion pressure (SPP) could predict the outcome of ischemic wound healing.

PATIENTS AND METHODS

Sixty-two limbs in 53 patients with conservative therapy were enrolled in this study. A SPP value of 40 mmHg was adopted as the criterion for making clinical decisions. The outcome one month after SPP measurement was classified as "improved" (diameter of ulcer decreased ≥ 20% or demarcation of gangrene became well defined) or "no change or worse" (others), and the fate of wound was classified as "healed" or "not healed". The evaluated influential factors on the outcome at one month included age, sex, presence of arteriosclerosis obliterans, collagen disease, hypertension, diabetes mellitus, hemodialysis, wound infection, wound management, and SPP ≥ 40 mmHg.

RESULTS

Using a criterion of SPP ≥ 40 mmHg, the outcome at one month could be predicted with a sensitivity: of 75.0%, a specificity: of 82.6%, and an accuracy: of 80.6%. The receiver operating characteristic curve indicated our criterion to be appropriate. Logistic regression analysis showed SPP ≥ 40 mmHg to be an independent factor (P < 0.0001) with the odds ratio of 14.2 (95% CI 3.6-55.8).

CONCLUSIONS

SPP, using a cutoff value of 40 mmHg, can predict the ischemic wound healing with conservative therapy.

Skin perfusion pressure in chronic venous disorders

OBJECTIVE

To examine whether a patient group with chronic venous disorders (CVDs) would show a different response to a pressure provocation test, such as skin perfusion pressure (SPP) of microcirculatory function.

DESIGN

A cuff inflation technique was applied to the gaiter area of the lower legs to induce complete occlusion of the microcirculation. The cuff was then released to measure the pressure at which perfusion resumed, and SPP was measured with a laser Doppler flowmeter (LDF). The measurements at reperfusion were taken of skin of the lower legs of individuals with CVD and compared with the lower-leg skin of control participants.

MAIN OUTCOME MEASURES

To establish whether a measurable difference in SPP exists between the group with CVD and the group without CVD, the means of 9 measurements taken were compared using the Student t test. The lowest value of the 9 measurements of minimum pressure (LMV) was used to estimate the pressure at which reperfusion occurred (SPP). The means of those estimates were then compared using the Student t test.

MAIN RESULTS

The mean LMV measured in the CVD group was slightly higher than that measured in the group without CVD. Although this could be considered a clinically significant result, it was not statistically different.

CONCLUSIONS

For this study, SPP was not significantly different for those with CVD compared with those without. These results suggest that SPP conducted with an LDF has little potential to detect "invisible" changes in the microcirculatory function of the skin affected by CVDs.

Ankle Peak Systolic Velocity: New Parameter to Predict Nonhealing in Diabetic Foot Lesions

The objective of this study was to determine whether ankle peak systolic velocity (APSV) can predict nonhealing in diabetic foot lesions. Diabetic patients referred for duplex scanning of the lower extremity arteries were included if they had foot lesions such as ulcers, gangrene, or tissue necrosis and had no palpable pedal pulses. End points were healed or healing foot lesions, revascularization, major amputation, or death. One hundred consecutive limbs were included. Forty-three limbs with diabetic foot lesions reached the end point of adequate healing or complete healing, whereas 57 limbs had nonhealing lesions. The APSV was significantly higher in limbs with healed or healing lesions compared with limbs with nonhealed lesions: 53.0 cm/s (41.8–81.6) versus 19.2 cm/s (12.4–26.5), p < .0001. At a cutoff point of 35 cm/s, the APSV showed a sensitivity of 92.9% (95% confidence interval [CI] 82–97), a specificity of 90.6% (95% CI 76–96), a positive predictive value of 92.9%, and a negative predictive value of 90.6% in predicting nonhealing of diabetic foot lesions. There was a significant difference between the APSV before and after revascularization: 20.4 cm/s (12.4–26.3) versus 48.8 cm/s (36.1–80.8), p < .0001. APSV could predict nonhealing of diabetic foot lesions with a high degree of accuracy in this group of patients.

Vasodilator response correlates with outcome in chronic critical limb ischemia

BACKGROUND

There are few predictors of limb salvage in patients with critical limb ischemia (CLI). We evaluated the accuracy of correlation of skin perfusion pressure (SPP) measurements in response to vasodilation to clinical outcome.

METHODS

Patients with CLI were evaluated by SPP at baseline. After injection of the vasodilator alprostadil, SPP was re-evaluated at 120 min and at day 7.

RESULTS

Patients showing clinical improvement demonstrated increased SPP in response to vasodilation (120 min: 34.12+/-2.44 to 48.33+/-3.41 mm Hg, P < 0.01; day 7: 33.13+/-3.14 to 45.83+/-3.79 mm Hg, P < 0.01), whereas patients who clinically deteriorated demonstrated no increase in SPP (120 min: 30.00+/-2.67 to 35.00+/-2.31 mm Hg, P = 0.086; day 7: 35.00+/-3.54 to 27.5+/-4.33 mm Hg, P = 0.22).

CONCLUSIONS

Prognosis for limb salvage correlated with SPP improvement post-vasodilator treatment after both early and late time points. Measurement of SPP after vasodilator treatment may be clinically useful in the treatment of patients with CLI. A multi-center trial of SPP in response to vasodilators is warranted.

Evaluation and treatment of leg ulcers associated with chronic venous insufficiency

The successful management of patients who have leg ulcers related to chronic venous disease requires optimal management of the wound bed, elimination of edema with compression, and correction of venous hypertension whenever possible. Healing of the wound itself requires compression, debridement, bacterial control, and stimulation of the wound bed. Prevention of ulcer recurrence is most effective if the patient is amenable to correction of the venous insufficiency. This is most successful when the superficial or perforator veins are the primary source. Quality diagnostic studies are critical in determining the anatomy and hemodynamic importance of various venous abnormalities and can guide appropriate interventional treatment. Venous corrective procedures usually can be performed using minimally invasive endovenous methods, which are associated with fewer complications and more rapid recovery than are major surgical techniques.

Assessment of lower limb ischemia with measurement of skin perfusion pressure in patients on hemodialysis

Measurement of skin perfusion pressure (SPP) using laser Doppler has become available for the assessment of peripheral arterial disease. We studied whether measurements of SPP can be used to identify hemodialyzed patients with peripheral arterial disease by comparing it with measurements of the ankle brachial pressure index (ABI). The ABI at rest and the SPP in the foot were measured in 59 Japanese hemodialyzed patients (118 limbs). Twenty-one patients had diabetes mellitus. Five had intermittent claudication; however, 20 patients were accompanied by other exertional leg symptoms. The SPP could not be measured in three limbs because of involuntary movement due to previous stroke or restless leg syndrome. The SPP was correlated with the ABI. Depending upon these results of the ABI, the 114 limbs from which both the ABI and the SPP could measured were divided into three groups: (A) ABI > or = 1.3, (B) 0.9 < or = ABI < 1.3, and (C) ABI < 0.9. The average SPP of group C was significantly decreased among the three groups. All subjects of the three groups were divided into an extra two groups according to the presence of diabetes (non-diabetes groups, -I; diabetes groups, -II). The average SPP of group B-II was significantly decreased compared with those of group B-I. The SPP measurement is a noninvasive, useful screening method for limb ischemia that can be applied to exercise tolerance limited patients. The SPP measurements are expected to be useful for the evaluation of limb ischemia in hemodialyzed patients at risk.

Transmetatarsal amputation: assessment of current selection criteria

BACKGROUND

Transmetatarsal amputation (TMA) is an operation designed to remove a limited area of irremediable tissue ischemia and/or infection and preserve limb function. Patients are selected for TMA based on degree of tissue loss/infection, adequacy of tissue perfusion at the transmetatarsal level, current ambulatory status, and estimation of the likelihood of postprocedure ambulation. The purpose of this study was to assess the validity of these selection criteria.

METHODS

An institutional review board-approved retrospective review was conducted of all patients undergoing TMA from January 1, 1997, until January 1, 2006. Information was collected on patient demographics, medical comorbidity, and clinical and surgical variables. Outcome measures included the proportion of patients requiring amputation revision to a more proximal level and ambulatory status at last follow-up.

RESULTS

Fifty-two TMAs were performed. In 35 procedures, the skin was left open, and in 17 TMA was closed primarily. Primary indications for the procedure were vascular insufficiency or infection in 50 of 52 patients, whereas 2 patients required amputation for malignancy. The majority (46/52, 89%) of patients were diabetic. After the index TMA, 85 additional operations were required. Only 9 patients (18%) underwent a single operation. Revision of the TMA to a more proximal level was required in 29 of 52 (56%) patients, resulting in 4 Syme, 20 transtibial, and 5 transfemoral amputations. Non-insulin-dependent diabetes was associated with an increased likelihood of revision to a more proximal amputation (odds ratio [OR] = 5.4; 95% confidence interval [CI], 1.2-24). At the time of last follow-up (median 18 months), 37 of 50 (74%) patients were ambulatory (83% for TMAs and 67% for more proximal amputations, P = 0.18). Prior vascular procedures were associated with a significantly decreased likelihood of ambulation (OR = 14; 95% CI, 1.9-103).

CONCLUSIONS

Although most patients retain the ability to ambulate after TMA, multiple operations should be anticipated in the majority of patients and revision of a TMA to a more proximal level may be required. These data suggest that current selection criteria for TMA may be inadequate.

Diabetic foot disorders. A clinical practice guideline (2006 revision)

The prevalence of diabetes mellitus is growing at epidemic proportions in the United States and worldwide. Most alarming is the steady increase in type 2 diabetes, especially among young and obese people. An estimated 7% of the US population has diabetes, and because of the increased longevity of this population, diabetes-associated complications are expected to rise in prevalence. Foot ulcerations, infections, Charcot neuroarthropathy, and peripheral arterial disease frequently result in gangrene and lower limb amputation. Consequently, foot disorders are leading causes of hospitalization for persons with diabetes and account for billion-dollar expenditures annually in the US. Although not all foot complications can be prevented, dramatic reductions in frequency have been achieved by taking a multidisciplinary approach to patient management. Using this concept, the authors present a clinical practice guideline for diabetic foot disorders based on currently available evidence, committee consensus, and current clinical practice. The pathophysiology and treatment of diabetic foot ulcers, infections, and the diabetic Charcot foot are reviewed. While these guidelines cannot and should not dictate the care of all affected patients, they provide evidence-based guidance for general patterns of practice. If these concepts are embraced and incorporated into patient management protocols, a major reduction in diabetic limb amputations is certainly an attainable goal.

When is a more proximal amputation needed?

Amputation may be the most appropriate therapy for an ischemic or infected limb, but the level at which to amputate is often difficult to determine. Selecting the appropriate level is crucial when performing an amputation. The goals of surgery are to maintain maximal limb length and ensure successful healing. When more of the foot and limb can be preserved, the chances for rehabilitation are improved. This article reviews how to determine the most appropriate level of amputation.

Skin perfusion pressure of the foot is a good substitute for toe pressure in the assessment of limb ischemia

PURPOSE

Noninvasive measurements of limb systolic pressures are used routinely in the assessment of the severity of peripheral arterial disease, including the evaluation for critical limb ischemia. However, ankle pressures cannot be measured reliably in patients with medial calcification, which is especially common among patients with diabetes. Skin lesions on the toes or previous digital amputations may preclude the measurement of toe pressures. Measurements of skin perfusion pressure (SPP) are not subject to such limitations and were shown to be useful in the assessment of the severity of peripheral arterial disease. Because toe pressure is often used in the evaluation of severity of arterial disease and in the assessment for critical ischemia, we undertook to study whether there is a sufficient correlation between toe pressure and foot SPP that would allow the use of SPP measurements when toe pressures cannot be measured.

METHODS

Measurements were carried out in 85 limbs of 71 patients referred to the vascular laboratory for evaluation for peripheral arterial disease. Diabetes mellitus was present in 43 patients. Each patient had foot SPP and toe pressure measurements. Toe pressures measured with photoplethysmography were correlated with foot SPP measured with laser Doppler scanning.

RESULTS

There was a strong linear correlation between SPP and toe pressure (r = 0.87; P <.01). Also, significant correlation was found in both the patients with diabetes and the patients without diabetes (r = 0.85 and 0.93, respectively; P <.01 in both cases).

CONCLUSIONS

We concluded that SPP measured in the foot correlates well with toe pressure and can be substituted for toe pressure measurement in patients in whom toe pressures cannot be measured.