Ulcerated edematous limbs: effect of edema removal on transcutaneous oxygen measurements

Correlation of ACR and TcPO2 in diabetic kidney disease patients: A pilot study

OBJECTIVE

Transcutaneous oxygen pressure (TcPO2) is used to assess microcirculation clinically; however, it is not widely available especially in rural hospital. The study was designed to explore potential alternatively biomarkers to assess microcirculation in diabetic kidney disease (DKD).

METHODS

A total of 404 patients from Xuzhou first hospital were recruited according to the case records system. Patients were grouped via the ratio of albuminuria and creatinine (ACR; <30 mg/g, 30-300 mg/g, >300 mg/g). Biomarkers in different ACR groups were compared by analysis of variance. Correlation analysis was determined by Pearson or Spearman analysis and binary logistic regression. The receiver operating characteristics (ROC) curve was performed to elucidate the prediction effect of ACR on TcPO2.

RESULTS

A total of 404 diabetic patients were recruited with 248 patients diagnosed as DKD and 156 non-DKDs. Age and cystatin C were significantly higher in the ACR3 group compared with those in the ACR1 group, whereas glomerular filtration rate, low-density lipoprotein cholesterol, and TcPO2 were markedly decreased in the ACR3 group (p < .05). Frequency of low TcPO2 (<40 mm Hg) was markedly increased as increment of ACR stages with 30.2% in the ACR3 group (p < .01). There was a negative correlation between TcPO2 and age, ACR, chronic kidney disease (CKD), fast blood glucose, diabetes mellitus (DM) duration, and diabetic neuropathy. Further, binary logistic regression showed ACR was an independent influence factor for low TcPO2. After adjusting for age, gender, hypertension, DM duration, body mass index, glycated hemoglobin, diabetic neuropathy, and CKD, ACR was still an independent influence factor for TcPO2 (odds ratio = 2.464, p < .01). The area under the ROC curve was 0.768 (95% confidence interval: 0.700-0.836, p < .001) for ACR. The analysis of ROC curves revealed a best cutoff for ACR was 75.25 mg/g and yielded a sensitivity of 71.7% and a specificity of 71.7%.

CONCLUSIONS

ACR could be used as an alternative biomarker for assessing microcirculation in DKD patients.

Oxygen tension assessment: an overlooked tool for prediction of delayed healing in a clinical setting

Successful wound healing requires adequate transcutaneous oxygen tension (tcpO(2) ). TcpO(2) may not commonly be incorporated in clinical assessments because of variable measurement response at different sensory temperatures. This study aims to assess the relationship between changes in tcpO(2) , measured under basal (39°C) and stimulated (44°C) conditions and healing rate of chronic wounds over 4 weeks, to determine whether tcpO(2) measurement can predict delayed wound healing. TcpO(2) (Radiometer TCM400) measurements at sensor temperatures 39 and 44°C were recorded (twice, 4 weeks apart) adjacent to the ulcer site, and at a mirror image site on the contralateral leg. Ulcer outline was traced on clear acetate and perimeter and area measured (Visitrak™, Smith and Nephew). TcpO(2) measured at 44 and 39°C adjacent to all 13 wounds were lower compared to the contralateral site, significant at 44°C (P = 0·008). Significant correlation (r(2) = 0·8) occurred between wound healing rate and increased tcpO(2) at 44°C over 4 weeks. Importantly, the ratio of 39/44°C tcpO(2) , measured at the initial appointment, appeared to predict normal or delayed healing rate. TcpO(2) may provide clinicians with information regarding anticipated healing ability of wounds at the initial appointment, and hence identify wounds requiring early implementation of adjuvant therapies to accelerate healing.

Intermittent pneumatic compression: physiologic and clinical basis to improve management of venous leg ulcers

Venous leg ulcers (VLUs) are a significant health problem that afflicts 1% of the population at some point during their lifetime. Intermittent pneumatic compression (IPC) is widely used to prevent deep venous thrombosis. However, IPC seems to have application to a broader base of circulatory diseases. The intermittent nature of pulsatile external compression produces beneficial physiologic changes, which include hematologic, hemodynamic, and endothelial effects, which should promote healing of VLUs. Clinical studies of the management of VLUs show that IPC increases overall healing and accelerates the rate of healing, leading to current guideline recommendations for care of patients with VLUs. Proper prescription of IPC to improve the management of patients with VLUs requires further definition. It seems that application of IPC in combination with sustained graduated compression improves outcome in patients with the most advanced venous disease.

Use of intermittent pneumatic compression in the treatment of venous ulcers

Venous ulcers affect up to 1% of the population. This review provides the hemodynamic, hematologic and clinical effects of intermittent pneumatic compression (IPC) in the treatment of venous ulcers. It presents the different IPCs and their application on venous disease. It points out that a large randomized study on IPC versus standard four-layer compression in the treatment of venous ulcers is needed. The cost–effectiveness of IPC in the treatment of venous ulcers should also be assessed.

Use of the sensory nerve stimulator to accelerate healing of a venous leg ulcer with sensory nerve dysfunction: a case study

A new therapy using sensory nerve stimulation [International Patent Application Number PCT/AU2004/001079: "nerve function and tissue healing" (Khalil, Z)] has been developed in our vascular physiology laboratory. This treatment has been found to improve the deficient sensory nerve function and associated deficient wound healing of older persons to levels seen in young people. An 82-year-old man with a small but persistent venous leg ulcer for 18 months, despite apparently appropriate wound dressings and compression therapy, was seen in a specialist wound management service. The patient's sensory and microvascular function was assessed in great detail using the vascular physiology laboratory techniques, and he was provided the sensory nerve stimulation therapy in addition to conventional therapy. His wound healed after 4 weeks. We report the case here. Prior to nerve stimulation therapy, cutaneous sensation, microvascular blood flow and oxygen tension were found to be reduced near the ulcer when compared with the opposite, non ulcerated leg. After therapy, oxygen tension and microvascular blood flow had improved. This case provides further evidence that sensory nerve stimulation therapy at the stipulated parameters improves wound healing. The observation that sensory nerve function improved provides support for the notion that improvement in healing is mediated by improved nerve function.

Age-related changes in microvascular blood flow and transcutaneous oxygen tension under Basal and stimulated conditions

BACKGROUND

Adequate cutaneous microvascular blood flow and tissue oxygen tension are important prerequisites for successful tissue repair. The efficacy of tissue repair decreases with age and is linked to the age-related functional decline of unmyelinated sensory neurons that are important for inflammation and tissue repair. However, available information on the effect of these neuronal changes on microvascular blood flow and tissue oxygen tension is limited, particularly under control and injury conditions. The authors had two aims in this study: (a) to assess age-related changes in the relationship between microvascular blood flow and tissue oxygen perfusion under basal and two different stimulated conditions (sensory dependent and sensory independent), and (b) to clarify the biological meaning of transcutaneous partial pressure of oxygen (tcPO2) measurements.

METHODS

The effects of a sensory-independent vasodilator (acetylcholine) and a sensory-dependent vasodilator (capsaicin) on microvascular blood flow and oxygen perfusion in persons of different ages were measured. Laser Doppler flowmetry and a commercially available transcutaneous oxygen monitor (with sensors set at 39 degrees C and 44 degrees C) were used. Healthy volunteers were recruited: 11 young, 14 middle aged, and 19 older.

RESULTS

Under basal conditions (skin temperature, 37 degrees C to 39 degrees C), both basal blood flow and tcPO2 increased with increasing age. However, with the sensor set at 44 degrees C, tcPO2 showed a significant decrease with age. Acetylcholine increased blood flow approximately equally in the three age groups. Capsaicin increased blood flow and tcPO2 in all age groups, with the young showing a greater increase compared with the older participants.

CONCLUSIONS

The age-associated changes in basal and stimulated microvascular blood flow and tcPO2 could be attributed in part to altered neuronal function. Measuring tcPO2 at 39 degrees C showed a trend toward an increase with age. In contrast, a decrease with age was observed when tcPO2 was measured at 44 degrees C, a temperature sufficient to activate sensory nerve endings. The results may reflect a decline in sensory nerve function with age rather than a decrease in oxygen delivery for vascular reasons. This is supported by the complementary data showing a significant age-related decrease in stimulated blood flow in response to capsaicin, with no change in the response to the sensory-independent vasodilator acetylcholine. Thus, for clinical purposes, data obtained using the tcPO2 monitor should be interpreted with full knowledge of the conditions under which the measurements were made. Furthermore, for scientific purposes, the tcPO2 monitor could be used to assess sensory nerve function when sensors are heated to 44 degrees C.

A systematic review of pneumatic compression for treatment of chronic venous insufficiency and venous ulcers

INTRODUCTION

As part of a reconsideration of coverage policy, the Centers for Medicare and Medicaid Services requested a systematic review of the evidence on the use of pneumatic compression devices in the home environment for treatment of chronic venous insufficiency (CVI) and venous ulcers.

METHODS

Articles were found with a systematic literature search of MEDLINE, EMBASE, and AMED (Allied and Complementary Medicine) databases, hand searches of reference lists, and suggestions of experts.

RESULTS

Eight trials that met the inclusion criteria, including several randomized control trials, were found. Most studies were small and may have been underpowered. However, several were well-designed randomized controlled trials. Three studies showed that the devices could alleviate symptoms of CVI. No studies directly measured whether the devices could prevent the occurrence of venous ulcers. Some studies on the treatment of venous ulcers did not show a benefit for pneumatic compression, but other studies showed a benefit for the devices in healing long-standing chronic ulcers that had not healed with other methods. No studies directly compared single-chamber and multiple-chamber devices or studied whether the effectiveness of the pump was dependent on types of treatment used concurrently with the pump. Few adverse events were reported in the trials. Patients generally expressed satisfaction with the pneumatic compression devices, and several studies reported higher compliance than with other compression methods.

CONCLUSION

The available data cannot be relied on to inform the optimal choice of compression therapy or optimal protocol for patients with CVI or venous ulcers. Methodologically rigorous research designed to answer these questions would be useful for treatment decisions. The Centers for Medicare and Medicaid Services considered the results of this study and issued a decision that pneumatic compression will only be covered for patients with refractory edema with significant ulceration of the lower extremities after a 6-month trial of standard therapies, such as compression stockings, has failed.

Intermittent Pneumatic Compression Devices – Physiological Mechanisms of Action

There are many reports of how IPC is used effectively in the clinical setting; including the prevention of deep venous thrombosis, improvement of circulation in patients with lower extremity arterial diseases, reduction of lymphoedema, and the healing of venous ulcers. However, despite the widely accepted use of IPC, it is still unclear how IPC actually exerts its beneficial effects. The exact physiological mechanisms of action are unknown. The clinical utility of IPC and the putative mechanisms by which IPC could exert its therapeutic effect will be reviewed. The paper will examine the mechanical effects of IPC exerted on the lower extremity, and the subsequent biochemical changes in the circulation. In vitro studies of the effects of mechanical stress such as compressive strain and shear on cultured endothelial cells, and their clinical relevance to IPC will also be reviewed.

The use of intermittent pneumatic compression in venous ulceration

Even with the application of four-layer bandaging, the recommended treatment for venous leg ulceration, patients with reduced mobility have delayed ulcer healing. Intermittent pneumatic compression (IPC) has an established role in deep vein thrombosis prophylaxis and has been shown to influence fibrinolysis, tissue oxygenation, oedema and venous return. It has also been suggested, but not yet proven, that IPC may improve the healing of venous leg ulcers. An extensive review of the literature has demonstrated that the use of this treatment on patients with reduced mobility has not been previously studied; yet, analysis of difficult-to-heal ulcer patients would indicate that this method of treatment may be appropriate and requires further study.

The microcirculation in venous hypertension

Venous ulceration is a common problem in western countries and results in large costs to healthcare systems. A number of hypotheses of the mechanisms of development of venous ulceration have been advanced, but this question has not been fully resolved. In recent years research effort has focused on the microcirculation of the skin and many methods of investigation have been employed to study this. Some of the principal findings described in published work are reviewed in this article. It seems unlikely from the available evidence that venous ulceration is attributable solely to failure of diffusion of oxygen and other small nutritional molecules to the tissues of the skin. The microvascular changes in the skin are characterised by activated endothelium and perivascular inflammatory cells. It is much more likely that leucocytes attach themselves to the cutaneous microcirculation, become activated and produce endothelial injury. Repeated over many months or years, this chronic inflammatory process leads to be tissues changes of lipodermatosclerosis. Although there is evidence of leucocyte involvement in the pathogenesis of venous ulceration, the exact mechanisms remain to be resolved. Improved treatment for patients may be devised once a better understanding of the basic causes of this condition has been reached.

Compression therapy

BACKGROUND

Compression therapy is the standard care for venous insufficiency ulcers. It reverses some of the underlying pathologies and restores a functional calf pump unit.

OBJECTIVES

To review the pathophysiology of venous ulcers and the different types of compression devices available.

RESULTS

The choice of a compression device should be individualized and tailored to the need of the patient. It should be applied by skilled nurses or physicians.

CONCLUSION

Compression therapy continues to constitute the standard therapy for venous insufficiency ulcers.

Transcutaneous oxygen measurement in stroke: circulatory disorder of the affected leg?

OBJECTIVE

To identify variances in the microcirculation of the affected leg of stroke patients and to correlate them with a number of variables that are clinically associated with a possible circulatory disorder ("cold leg").

DESIGN

Survey.

SETTING

Large regional (tertiary care) rehabilitation center.

PATIENTS

From 93 acute, first-ever stroke patients admitted for stroke rehabilitation, 10 individuals were selected. Patients with vascular or cardiopulmonary pathology and severe cognitive or speech impairments were excluded.

MAIN OUTCOME MEASURES

A clinical assessment of the following variables was performed: subjective complaints of the affected leg, medication, walking performance, degree of lower-leg edema, trophic pathology, voluntary muscle activity of the dorsal flexors of the affected foot, and the degree of spasticity of the calf muscles. The microcirculation of the affected leg was registered via transcutaneous oxygen measurement (TcPO2).

RESULTS

The clinical picture associated with a circulatory disorder ("cold leg") was partially and modestly present in seven patients. The TcPO2 values showed no differences between the paretic and nonparetic lower legs, nor did values change in the course of time after stroke: mean 77.9 mmHg (range 42-124) versus 86.1 (41-124) after 8 weeks (n = 10, p = .17); 76.9 (45-96) versus 73.1 (50-96) after 14 weeks (n = 9, p = .38); and 65.8 (44-88) versus 65.8 (37-78) after 20 weeks (n = 8, p = .48). The clinical symptoms could not be objectified in relation to the microcirculation.

CONCLUSIONS

In selected stroke patients, no differences were established between microcirculation in both lower legs. TcPO2 measurement does not seem to be a suitable method for clinical research on this topic.

Healing determinants in older people with leg ulcers

A descriptive correlational design was used to identify the physiologic, therapeutic, and psychosocial determinants of leg ulcer healing in community-residing older people with venous and venous-arterial disease (N = 156). A regression model with healing rate as the dependent variable explained 49% of the variance. Increased pain when mobilizing, increased hours with limbs horizontal to the torso, and moderate and severe liposclerosis (hardening and induration of the skin) were associated with poorer healing rates. Higher wound status scores were associated with more rapid healing rates. Self-efficacy beliefs and social support were not significant factors. The findings suggest the need for early detection and management of limb pain that interferes with normal mobility. Limb position and edema assessment prior to the application of compression bandages is recommended, with bandages that provide clients with high compression when ambulant and low compression when resting being potentially beneficial.

Compression therapy of the legs. A review

Compression therapy is a powerful method for the treatment of all sorts of swollen extremities. Its effects depend on several factors, including: underlying disease, exerted pressure and body position, and compression material.

Lower leg subcutaneous blood flow during walking and passive dependency in chronic venous insufficiency

The blood flow in the subcutaneous adipose tissue of the lower leg of eight normal subjects and 19 patients with chronic venous insufficiency was measured. The 133Xe-washout technique was used with portable CdT1(C1) detectors and a data storage unit. Only those patients with ulcers and a systolic blood pressure at the toe of greater than or equal to 60 mm were investigated. In the controls the relative blood flow during sitting was 0.61 (range 0.35-0.80). In the patients it was 0.46 (range 0.22-0.87). This difference was not significant. During walking the blood flow increased in controls as well as in the patients compared to the value determined in the sitting position (P = 0.0078 and P = 0.0028, respectively, Wilcoxon matched-pairs test). The relative blood-flow rate during walking was 0.96 (range 0.60-1.58) in the controls, and 1.04 (range 0.49-1.46) in the patients. The difference between the normal subjects and the patients was not significant (P = 0.79). We conclude from our studies that patients with venous insufficiency are able to increase their blood flow during walking to the same extent as normal controls.

Clinical parameters and transcutaneous oxygen measurements for the prognosis of venous ulcers

Few data exist on the prognosis of venous ulcers. We therefore prospectively studied 14 patients with severe venous ulcers for up to 18 months and examined various possible prognostic factors, including transcutaneous oxygen tension (TcPO2) measurements of skin next to the ulcers. The ulcers had been present for a mean duration of 15.6 months before referral to our clinic. During the study only four patients (29%) had ulcers that were healed with conservative management consisting of topical and systemic antibiotics and conventional and occlusive dressings. We observed that the number of ulcers, their duration before admission to the study, and the extent of lipodermatosclerosis were more pronounced in the unhealed group. For all patients the mean ulcer TcPO2 level (5.6 +/- 1.5 mm Hg, mean +/- standard error) was significantly reduced when compared with the control chest site (62.4 +/- 2.1 mm Hg) (p less than 0.001; paired t test). The mean ulcer TcPO2 was not significantly different between the healed (4.5 +/- 2.0 mm Hg) and unhealed groups (6.1 +/- 2.0 mm Hg). We conclude that TcPO2 levels may not be predictive of the response to therapy in venous ulcers. TcPO2 levels may be markedly reduced, but even extremely low levels are not incompatible with healing.