The influence of diabetes and lower limb arterial disease on cutaneous foot perfusion

OBJECTIVE: Peripheral arterial occlusive disease and peripheral neuropathy are major risk factors in diabetic foot disease. We evaluated the relative influences of noncritical lower limb arterial disease and peripheral neuropathy on cutaneous foot perfusion in diabetes. METHOD: Toe-brachial pressure indices, transcutaneous oxygen, and carbon dioxide tensions at foot and chest sites were measured in individuals with diabetes, with or without detectable peripheral neuropathy and with or without significant arterial disease on color duplex imaging. Subjects without diabetes, with and without arterial disease, were used as controls. RESULTS: A total of 130 limbs were studied during an 8-month period. Toe-brachial pressure indices reflected the presence of arterial disease in all groups. Foot transcutaneous oxygen values were reduced in diabetes and correlated with chest transcutaneous oxygen values. Low foot transcutaneous oxygen with elevated transcutaneous carbon dioxide values were only demonstrated in individuals with diabetes, arterial disease, and peripheral neuropathy. Toe-brachial pressure indices demonstrated a positive correlation with foot transcutaneous oxygen values, but values >1.2 demonstrated a negative correlation. CONCLUSIONS: We demonstrated two influences on cutaneous foot perfusion in diabetes: (1) a global microcirculatory dysfunction, reflected in low chest and foot transcutaneous oxygen values, and (2) macrovascular disease as indicated by reduced toe-brachial pressure indices and foot transcutaneous oxygen values. Further, the results demonstrated that in diabetic individuals without critical limb ischemia, impaired foot perfusion secondary to arterial disease is amplified significantly by coexisting microcirculatory disease.     

The effect of different positions on lower limbs skin perfusion pressure

We have encountered situations of patients with critical limb ischemia accompanied by pain at rest and necrosis, who hang their legs down from the bed during sleep. This lower limb position is known to be a natural position, which reduces pain in the lower extremity induced by ischemia. However, the effect of this position on blood flow of the lower extremity is poorly understood. We studied whether measurements of skin perfusion pressure (SPP) changes by leg position and the difference between healthy adults and patients with critical limb ischemia. The subjects of this study were 10 healthy adults and 11 patients with critical limb ischemia. Patients with critical limb ischemia, including both dorsum of foot and plantar of foot, having SPP of lower limbs of less than 40 mmHg (supine position) were the object of this study. SPP was measured on four positions (supine position, lower limbs elevation position, sitting position, and reclining bed elevation of 20^° position). In sitting position, both the number of healthy adults and critical patients show significant increases in SPP compared with the other three positions. These results suggest that sitting position is effective to keep good blood stream of lower limbs not only in healthy adults but also in patients with critical limb ischemia. However, an appropriate leg position should not have lower limbs hang downwards for long periods time because edema is caused by the fall in venous return in lower limbs, and the wound healing is prolonged.Our clinical research could be more useful in the future, particularly in developing countries, for surgeons managing wounds in leg and foot and preserving ischemic limbs.KEY WORDS: Critical limb ischemia, peripheral arterial disease, position, skin perfusion pressure     

Skin perfusion pressure in the prediction of healing in diabetic patients with ulcers or gangrene of the foot

The measurement of skin perfusion blood pressure (SPP) estimated by an isotope clearance technique has been used to predict the healing of ulcers or gangrene of the foot in 61 diabetic subjects. Healing followed conservative treatment or local surgery in 1 of 21 cases if the SPP was less than 40 mm Hg but in 35 of 40 with higher values for SPP. Healing was unlikely if the toe blood pressure was less than 40 mm Hg or the ankle systolic pressure was less than 80 mm Hg. It is recommended that the SPP be measured in patients in whom confident predictions of healing cannot be made on the basis of ankle pressure or other measurements.     

Transcutaneous carbon dioxide tension for the evaluation of limb ischemia

Purpose  Understanding the hemodynamics of critical limb ischemia caused by chronic peripheral arterial occlusive disease is important to evaluate its severity and the efficacy of treatment. We investigated the usefulness of transcutaneous carbon dioxide tension (tcPCO₂) measurement for evaluating ischemic limbs, in conjunction with the measurement of ankle pressure (AP), toe pressure (TP), skin perfusion pressure (SPP), and transcutaneous oxygen tension (tcPO₂). Methods  We measured tcPCO₂ in the dorsum of the foot in 158 patients (304 limbs) with arteriosclerosis obliterans. Results  The tcPCO₂ in normal limbs without any clinical sign or abnormal noninvasive measurement was 43.7 ± 3.7 mmHg; that in noncritical ischemic limbs was 45.5 ± 9.0 mmHg, which was not significantly different from that in the normal limbs; and that in critically ischemic limbs was 87.6 ± 35.5 mmHg, which was significantly different from that in the normal limbs. All limbs with a tcPCO₂ of 100 mmHg or higher, indicative of critical ischemia, had a tcPCO₂ of less than 100 mmHg after revascularization. Conclusion  We found tcPCO₂ to be a useful measurement for diagnosing the severity of limb ischemia, and for evaluating the effect of treatment, especially in patients with critically ischemic limbs.     

Clinical reliability and utility of skin perfusion pressure measurement in ischemic limbs--comparison with other noninvasive diagnostic methods

PURPOSE: We studied whether the measurement of skin perfusion pressure (SPP) is useful for evaluating ischemic limbs and predicting wound healing. METHODS: Two hundred eleven patients (age range, 45 to 90 years; mean age, 69.6 +/- 9.2 years; 170 men and 41 women), 403 limbs with arteriosclerosis obliterans, were included in this study. Half of the patients had diabetes or were receiving dialysis or both. RESULTS: Significant correlations were found between SPP and ankle blood pressure (ABP), SPP and toe blood pressure (TBP), and SPP and the transcutaneous oxygen pressure (tcPO2) (P < .0001, r = 0.75; P < .0001, r = 0.85; P < .0001, r = 0.62; respectively). In 94 limbs with ulcer or gangrene, wound healing was predicted by the SPP. The mean SPP (mean +/- SD) in the healed-wound group (25 limbs, 48 +/- 20 mm Hg) was greater than that in the unhealed-wound group (69 limbs, 23 +/- 11 mm Hg) (P <.001). According to the receiver operating characteristic (ROC) curve, the cut-off value of SPP was 40 mm Hg (sensitivity, 72%; specificity, 88%). Furthermore, we studied whether the combination of SPP and another measurement could predict wound healing more accurately than could any single variable. There was a strong correlation between SPP, TBP, and the healing rate (P < .001, r = 0.69) and healing could be accurately predicted if the SPP was greater than 40 mm Hg and if the TBP was greater than 30 mm Hg. CONCLUSIONS: Our results suggest that measurement of SPP is an objective method for assessing the severity of peripheral arterial disease or for predicting wound healing.     

Noninvasive determination of skin perfusion pressure using a laser Doppler

Laser Doppler (LD) measures blood flow in approximately one cubic millimeter of tissue. The LD instrument is well suited to the determination of the initiation of flow in the microcirculation after a period of arrest due to externally applied counterpressure. Radioisotope clearance and photoplethysmography have been used to measure skin perfusion pressure (SPP) in an effort to predict healing of ischemic ulcerations and amputation wounds. By placing the LD probe beneath a blood pressure cuff, SPP was measured at the forearm, thigh, calf, foot, dorsal and plantar great toe. The SPP was measured in 32 normal limbs and 26 limbs with rest pain, ulceration or gangrene. Skin of normal extremities and forearm and thigh skin of patients with ischemic lower extremities had a mean SPP of 47 mmHg (+/- 5 SEM). The SPP in ischemic extremities was significantly lower at the calf 22 +/- 4 (p less than .001), the foot 10 +/- 2 (p less than .0001), and the toe 16 +/- 4 (p less than .0001). SPP was greater at the plantar toe (73 +/- 5) than in all other locations. Skin of the plantar toe was unique among the sites measured because it is rich in arteriovenous anastomoses, which have a thermoregulatory function. The higher pressure probably reflects the fact that the larger arterioles have a higher intraluminal pressure than the capillaries and, therefore, a more proximal level of the microcirculation is measured by the LD instrument in thermoregulatory areas of the skin.(ABSTRACT TRUNCATED AT 250 WORDS)     

The value of toe pulse waves in determination of risks for limb amputation and death in patients with peripheral arterial disease and skin ulcers or gangrene

OBJECTIVES: The purpose of this study was to determine whether the presence of low amplitude of pulse waves recorded from the toes is related to the risk of subsequent amputation and death in patients with skin ulcers or gangrene and peripheral arterial disease, and how the risk of low wave amplitude relates to the risk associated with low peripheral pressures. METHODS: A total of 309 patients with 346 limbs with skin lesions and arterial disease referred to the vascular laboratory were followed up for an average of 5 years (range, 1-8 years). Measurements were carried out to obtain ankle and toe pressures, pressure indices, and toe pulse wave amplitude. These variables were related to the risks of major amputation and total and cardiovascular death by means of the Cox proportional hazards model. RESULTS: Low toe pulse wave amplitude (< or = 4 mm) was associated with increased risk of amputation (relative risks 4.20 in all limbs and 2.63 in those with toe pressure < or = 30 mm Hg; P <.01). Wave amplitude remained significantly associated with increased risk of amputation after controlling for each pressure variable (P <.01). Low pulse wave amplitude and toe/brachial index were associated with increased risks of both total and cardiovascular death in all patients (relative risks ranged from 1.43-1.73; P <.05) and in those with toe pressure of 30 mm Hg or less (relative risks 1.56-1.90; P <.05). CONCLUSIONS: Low toe pulse wave amplitude is related significantly to increased risks of amputation and death in patients with skin lesions and arterial disease. The presence of low wave amplitude provides significant information in addition to peripheral pressures with respect to the risk of amputation.     

A prospective comparison of bilateral photoplethysmography versus the ankle-brachial pressure index for detecting and quantifying lower limb peripheral arterial disease

OBJECTIVE: This study prospectively assessed the diagnostic accuracy of a novel bilateral photoplethysmography toe pulse measurement technique for the detection of significant lower limb peripheral arterial disease. METHOD: Bilateral photoplethysmography toe pulse measurements were compared with the ankle-brachial pressure index (ABPI) gold standard reference. Pulse wave analysis techniques extracted timing, amplitude, and shape characteristics for the great toes and their right-to-left side differences. These characteristics were compared with previously obtained normative ranges, and the accuracy was assessed for all significant disease (ABPI <0.9) and higher-grade disease (ABPI <0.5). Measurements were collected in a controlled environment within a tertiary vascular surgical unit for 111 subjects (age range, 42-91 years), of whom 48 had significant lower limb peripheral arterial disease and 63 were healthy. Subjects were matched in age, sex, height, body mass index, and heart rate. Diagnostic performance was assessed using diagnostic sensitivity, specificity, accuracy, negative-predictive and positive-predictive value, and the kappa statistic representing agreement between techniques beyond chance. RESULTS: The degree that pulse shape fell beyond the normal range of normalized pulse shapes was at the threshold of substantial to almost perfect agreement compared with ABPI for significant disease detection (diagnostic accuracy, 91% [kappa = 0.80]; sensitivity, 93%; specificity, 89%), and with 90% accuracy (kappa = 0.65) for higher-grade disease detection. Pulse transit time differences between right and left toes also had substantial agreement with ABPI, with diagnostic accuracy of 86% for significant disease detection (pulse transit time to pulse foot [kappa = 0.71] and to pulse peak [kappa = 0.70]) and reached at least 90% for these for the higher-grade disease. The performance ranking for the different pulse features mirrored an earlier pilot study. With the shape and pulse transit time measurements, the negative-predictive values of the 5% disease population screening-prevalence level were at least 99% and had positive-predictive values of at least 98% for the 90% disease-prevalence level for vascular laboratory referrals. CONCLUSION: This simple-to-use technique could offer significant benefits for the diagnosis of peripheral arterial disease in settings such as primary care where noninvasive, accurate, and diagnostic techniques not requiring specialist training are desirable. Improved diagnosis and screening for peripheral arterial disease has the potential to allow identification and risk factor management for this high-risk group.     

Toe pressure determination by audiophotoplethysmography

Purpose: The purpose of this study was to evaluate the performance of audio-photoplethysmography as a modality to measure toe pressure without the requirement of a recorder.Method: A portable photoplethysmograph with an audio output was used to determine toe pressures, and the results were compared with those obtained by a commercial photoplethysmograph with a recorder.Results: Thirty-one measurements in control subjects and 62 measurements in patients with arterial occlusive disease were performed. The average toe pressure recorded with oscillography with standard photoplethysmography was 103.5 mm Hg ± 14.7 SD and 95.9 mm Hg ± 13.4 SD with audio-photoplethysmography. In the patient group the pressure recorded with a commercial photoplethysmograph was 65.3 mm Hg ± 34.9 SD compared with 61.6 mm Hg ± 34.8 SD obtained with audio-photoplethysmography. The difference in both groups was insignificant, and the correlation between both methods was very good.Conclusion: A portable handheld photoplethysmograph equipped with an audio output was used to measure toe pressure in control subjects and in patients with arterial occlusive disease. The results have been compared with the oscillometric method by a standard commercial photoplethysmograph connected to a recorder. The correlation was very good in the control and patient groups, and the difference between both methods was below the level of statistical significance. The fact that no recorder is needed may help in introducing toe pressure measurement into everyday office diagnostic practice. (J VASC SURG 1994;20:267-70.)     

Update and validation of the Society for Vascular Surgery wound,ischemia, and foot infection threatened limb classification system

The diagnosis of critical limb ischemia, first defined in 1982, was intended to delineate a patient cohort with a threatened limb and at risk for amputation due to severe peripheral arterial disease. The influence of diabetes and its associated neuropathy on the pathogenesis-threatened limb was an excluded comorbidity, despite its known contribution to amputation risk. The Fontaine and Rutherford classifications of limb ischemia severity have also been used to predict amputation risk and the likelihood of tissue healing. The dramatic increase in the prevalence of diabetes mellitus and the expanding techniques of arterial revascularization has prompted modification of peripheral arterial disease classification schemes to improve outcomes analysis for patients with threatened limbs. The diabetic patient with foot ulceration and infection is at risk for limb loss, with abnormal arterial perfusion as only one determinant of outcome. The wound extent and severity of infection also impact the likelihood of limb loss. To better predict amputation risk, the Society for Vascular Surgery Lower Extremity Guidelines Committee developed a classification of the threatened lower extremity that reflects these important clinical considerations. Risk stratification is based on three major factors that impact amputation risk and clinical management: wound, ischemia, and foot infection. This classification scheme is relevant to the patient with critical limb ischemia because many are also diabetic. Implementation of the wound, ischemia, and foot infection classification system in critical limb ischemia patients is recommended and should assist the clinician in more meaningful analysis of outcomes for various forms of wound and arterial revascularizations procedures required in this challenging, patient population.     

Segmental blood pressure of the leg and its clinical use

Systolic blood pressure at various levels of the leg was measured in 80 normal subjects by photoelectric plethysmography with a blood pressure cuff. Due to the higher pressure value at the tigh, calf, ankle, and foot and lower pressure value at the toe, the pressure gradient between each proximal site and the toe was significantly higher in the older (50–82) than in the younger age group (17–49). Therefore, normal values were determined separately in these two groups. In 64 limbs of 42 patients with arterial occlusive disease, a comparison between segmental blood pressure and arteriographic findings was made. Segmental blood pressure may be a rough indicator of the severity of arterial occlusion present and may refrect the status of the major conduits of the leg. An abnormal ankle-toe pressure gradient was found in only 52 per cent of limbs, although all 64 limbs had undergone an occlusive process distal to the ankle. In limbs with significantly low ankle blood pressure due to proximal lesions, less frequency and severity of an abnormal ankle-toe pressure gradient were seen than in limbs with normal ankle blood pressure. When pressure gradients between two different levels are used in clinical work, the blood pressure at the more proximal level should be always considered.     

Peripheral arterial disease as a predictor of outcome after renal transplantation

Our aim was to assess the prevalence of symptomatic and asymptomatic peripheral occlusive arterial disease (POAD) in 129 consecutive diabetic (n = 34) and non-diabetic (n = 95) patients undergoing renal transplantation. The association of pre-existent POAD and complaints of claudication, lower limb amputations, and graft and patient survival were evaluated during a 5-year follow up. A questionnaire on walking capacity, ankle/brachial (ABI) and toe/brachial (TBI) pressure indices as well as the pulse volume recording (PVR) at the ankle were used to assess resting haemodynamics and the presence of POAD 4 days after the transplantation. Unquestionable ischaemia was encountered in 5 (4 %) patients all with a history of intermittent claudication and an ABI equal or below 0.77. While using assessment methods not affected by vessel calcification, i. e. toe pressures and PVR damping, a many-fold frequency of arterial disease was observed when compared to previous studies. TBI below 0.65 was found in 11 of diabetic (32 %) and in 15 of the others (16 %), and a PVR amplitude below 5 min in 28 of diabetics (82 %) and in 34 of non-diabetics (36 %). During the 5-year follow up, abnormal TBI and PVR values and diabetes at the time of transplantation were the greatest risk factors for proximal foot amputations. The low TBI levels also indicated a shortened patient survival. However, transplant function was not affected by the presence of abnormal haemodynamic indices at the time of transplantation.     

Why critical limb ischemia criteria are not applicable to diabetic foot and what the consequences are

Neuropathy, peripheral arterial occlusive disease and microvascular disturbances are important factors contributing to foot problems in diabetic patients. In the diabetic foot with ischemia, the alterations in skin microvascular function are pronounced including severely reduced capillary circulation and abolished hyperaemic responses. These microvascular disturbances, which are superimposed on the already existing structural diabetic microangiopathy, are compatible with a state of "chronic capillary ischemia" and an increased shunting of blood through arteriovenous channels. This maldistribution of blood in skin microcirculation is not detected by measurement of peripheral blood pressure (systolic ankle blood pressure, systolic toe blood pressure). As indicated in several studies toe blood pressure is a poor predictor of local tissue perfusion, tissue survival and healing of chronic foot ulcers. Consequently, the disturbances in peripheral tissue perfusion of the diabetic foot may be underestimated leading to delayed vascular interventions and/or medical treatment. Thus, measurements of peripheral blood pressure, e.g. toe blood pressure, should be combined with investigations of local tissue perfusion in order to get an adequate estimation of peripheral tissue perfusion in diabetic patients. For this purpose local skin microcirculation can be investigated by transcutaneous oxygen tension of the forefoot. Also, due to these reasons, the threshold for revascularization should be lower in diabetic patients with foot ulcer.     

Peripheral arterial disease as a predictor of outcome after renal transplantation

Abstract Our aim was to assess the prevalence of symptomatic and asymptomatic peripheral occlusive arterial disease (POAD) in 129 consecutive diabetic ( n = 34) and non-diabetic ( n = 95) patients undergoing renal transplantation. The association of pre-existent POAD and complaints of claudication, lower limb amputations, and graft and patient survival were evaluated during a 5-year follow up. A questionnaire on walking capacity, ankle/brachial (ABI) and toe/brachial (TBI) pressure indices as well as the pulse volume recording (PVR) at the ankle were used to assess resting haemodynamics and the presence of POAD 4 days after the transplantation. Unquestionable ischaemia was encountered in 5 (4 %) patients all with a history of intermittent claudication and an ABI equal or below 0.77. While using assessment methods not affected by vessel calcification, i.e. toe pressures and PVR damping, a many-fold frequency of arterial disease was observed when compared to previous studies. TBI below 0.65 was found in 11 of diabetic (32 %) and in 15 of the others (16%), and a PVR amplitude below 5 min in 28 of diabetics (82 %) and in 34 of non-diabetics (36 %). During the 5-year follow up, abnormal TBI and PVR values and diabetes at the time of transplantation were the greatest risk factors for proximal foot amputations. The low TBI levels also indicated a shortened patient survival. However, transplant function was not affected by the presence of abnormal haemodynamic indices at the time of transplantation.     

Hemodynamic study of ischemic limb by velocity measurement in foot

By means of a tracer technique with 99mTc-pertechnetate, provided with seven zonal regions of interest, 6 mm in width, placed at equal spaces of 18 mm, from the toe tip to the midfoot at a right angle to the long axis of the foot, arterial flow velocity in the foot during reactive hyperemia was measured. The mean velocity in the foot was 5.66 +/- 1.78 cm/sec in 14 normal limbs, 1.58 +/- 1.07 cm/sec in 29 limbs with distal thromboangiitis obliterans (TAO), 0.89 +/- 0.61 cm/sec in 13 limbs with proximal TAO, and 0.97 +/- 0.85 cm/sec in 15 limbs with arteriosclerosis obliterans (ASO). The velocity returned to normal in all 12 limbs after successful arterial reconstruction, whereas the foot or toe blood pressure remained pathologic in 9 of the 12 limbs postoperatively; the velocity reverted to normal in 4 of 13 limbs after lumbar sympathectomy. When the velocity was normalized after operation, the ulceration healed favorably, and the ischemic limb was salvaged. The most characteristic feature of peripheral arterial occlusive disease of the lower extremity was a stagnation of arterial circulation in the foot, and the flow velocity in the foot was a sensitive predictive index of limb salvage.     

Improving limb salvage in critical ischemia with intermittent pneumatic compression: a controlled study with 18-month follow-up

BACKGROUND: Intermittent pneumatic compression (IPC) is an effective method of leg inflow enhancement and amelioration of claudication in patients with peripheral arterial disease. This study evaluated the clinical efficacy of IPC in patients with chronic critical limb ischemia, tissue loss, and nonhealing wounds of the foot after limited foot surgery (toe or transmetatarsal amputation) on whom additional arterial revascularization had been exhausted. METHODS: Performed in a community and multidisciplinary health care clinic (1998 through 2004), this retrospective study comprises 2 groups. Group 1 (IPC group) consisted of 24 consecutive patients, median age 70 years (interquartile range [IQR], 68.7-71.3) years, who received IPC for tissue loss and nonhealing amputation wounds of the foot attributable to critical limb ischemia in addition to wound care. Group 2 (control group) consisted of 24 consecutive patients, median age 69 years (IQR, 65.7-70.3 years), who received wound care for tissue loss and nonhealing amputation wounds of the foot due to critical limb ischemia, without use of IPC. Stringent exclusion criteria applied. Group allocation of patients depended solely on their willingness to undergo IPC therapy. Vascular assessment included determination of the resting ankle-brachial pressure index, transcutaneous oximetry (TcPO(2)), duplex graft surveillance, and foot radiography. Outcome was considered favorable if complete healing and limb salvage occurred, and adverse if the patient had to undergo a below knee amputation subsequent to failure of wound healing. Follow-up was 18 months. Wound care consisted of weekly débridement and biologic dressings. IPC was delivered at an inflation pressure of 85 to 95 mm Hg, applied for 2 seconds with rapid rise (0.2 seconds), 3 cycles per minute; three 2-hourly sessions per day were requested. Compliance was closely monitored. RESULTS: Baseline differences in demography, cardiovascular risk factors (diabetes mellitus, smoking, hypertension, dyslipidemia, renal impairment), and severity of peripheral arterial disease (ankle-brachial indices, TcPO(2), prior arterial reconstruction) were not significant. The types of local foot amputation that occurred in the two groups were not significantly different. In the control group, foot wounds failed to heal in 20 patients (83%) and they underwent a below knee amputation; the remaining four (17%, 95% confidence interval [CI], 0.59%-32.7%) had complete healing and limb salvage. In the IPC group, 14 patients (58%, 95% CI, 37.1%-79.6%) had complete foot wound healing and limb salvage, and 10 (42%) underwent below knee amputation for nonhealing foot wounds. Wound healing and limb salvage were significantly better in the IPC group (P < .01, chi(2)). Compared with the IPC group, the odds ratio of limb loss in the control group was 7.0. On study completion, TcPO(2) on sitting was higher in the IPC group than in the control group (P = .0038). CONCLUSION: IPC used as an adjunct to wound care in patients with chronic critical limb ischemia and nonhealing amputation wounds/tissue loss improves the likelihood of wound healing and limb salvage when established treatment alternatives in current practice are lacking. This controlled study adds to the momentum of IPC clinical efficacy in critical limb ischemia set by previously published case series, compelling the pursuit of large scale multicentric level 1 studies to substantiate its actual clinical role, relative indications, and to enhance our insight into the pertinent physiologic mechanisms.     

Characteristics of peripheral arterial disease and its relevance to the diabetic population

Peripheral arterial disease (PAD) is very frequent in diabetics, and it increases with age. Foot examination contributes poorly to diagnosis of PAD. The ankle-brachial index (ABI) measurement is considered the most accurate noninvasive diagnostic method when evaluating PAD: ABI evaluation is recommended in all diabetics aged >50 years. Many diabetic patients with PAD have a concomitant sensitive neuropathy: as a consequence, perception of ischemic pain is remarkably reduced or completely blocked. The result is that the prevalence of claudication in the diabetic population with PAD is lower than the prevalence of critical limb ischemia (CLI) in this population. CLI is a major risk factor for lower extremity amputation without revascularization. Ankle and toe pressures and oxygen tension at the foot are the noninvasive diagnostic parameters of CLI though the medial artery calcification inhibits accurate determination of the ankle and toe pressures, especially when a forefoot ulcer is present. In diabetics, the anatomical localization is mainly distal; arterial wall calcification is frequently observed and occlusion occurs more frequently than stenosis. Such anatomical features, along with the difficulties in the diagnostic approach, account for the fundamental role of CLI as the main prognostic indicator for major amputation. PAD is an expression of systemic atherosclerotic disease. Prognosis of patients with PAD is related to the presence and extent of underlying coronary artery disease (CAD) but also to the severity of PAD: in particular, patients in whom revascularization is not feasible have the highest mortality rate.     

A new automated toe blood pressure monitor for assessment of limb ischemia.

OBJECTIVE: toe blood pressure (TBP) is an important method to assess peripheral arterial disease especially in patients with diabetes, but remains difficult to measure. We have developed a simple portable device for TBP measurements. METHODS AND RESULTS: first, TBP was determined in 40 ischemic legs with both laser Doppler and photoplethysmography for perfusion monitoring, to assess if laser Doppler can be used for measurements. The median values recorded were identical, but slightly higher values were obtained with laser Doppler (p=0.03). Secondly, a computer based algorithm for automatic TBP readings with laser Doppler was compared to manual assessment in 28 legs of 20 patients. The median values differed 3mmHg (p=0.10). Finally the applicability of the new device was tested in eight legs of six patients by two nurses. CONCLUSION: laser Doppler is appropriate for perfusion monitoring during TBP measurements and automatic pressure readings seem accurate. The automatic portable device is simple to use and can probably determine TBP.     

Skin vascular resistance and skin perfusion pressure as predictors of healing of ischemic lesion of the lower limb: influences of diabetes mellitus, hypertension, and age

An isotope washout technique that requires inexpensive equipment and is well tolerated by patients has been developed to measure skin perfusion pressure (SPP) and skin vascular resistance (SVR). The SPP is a measure of the severity of peripheral vascular disease and the SVR is an indicator of microangiopathy associated with diabetes mellitus and hypertension. This test has been applied to 87 patients who had ischemic lesions of the lower limb. Fourty-four patients had lesions that healed with local treatment while the other 43 required major surgery. The presence of diabetes, hypertension, and old age reduced the likelihood of healing. Similarly if the SPP less than 40 mm Hg, only 18% of patients' lesions healed. If the SPP lay between 40 and 50 mm Hg and the SVR less than 1000 U, 67% of lesions healed. However, if the SPP was between 40 and 50 mm Hg and the SVR greater than 1000 U, no lesions healed. If the SPP greater than 50 mm Hg and SVR less than 1000 U, 83% of lesions healed, where as if the SVR greater than 1000 U, healing occurred in only 23% of lesions. This test can be used to predict the likelihood of healing of ischemic lesions of the lower leg, thus rationalizing their management. The importance of microangiopathy is also demonstrated.     

Assessment of the microcirculation provides additional information in critical limb ischaemia.

Systolic ankle and toe pressure measurements are considered to be the best way of documenting arterial occlusive disease. In the European consensus, chronic critical limb ischaemia is defined as persistent pain with an ankle pressure lower than 50 mmHg. To investigate the possible adjunct value of microcirculatory assessment, capillary microscopy and transcutaneous oximetry were performed in 21 asymptomatic persons (F1), 89 claudicants (F2) and 54 patients with critical limb ischaemia (F3/4). Capillary morphology (diameter, density) and dynamics [red blood cell velocity (RBCV), peak RBCV and time to peak RBCV], as well as transcutaneous oximetry parameters were determined for each Fontaine group and compared with ankle and toe pressure measurements. Despite considerable overlap, ankle and toe pressures were significantly (p less than 0.001) different between F1, F2 and F3/4 patients. Capillary density (p less than 0.05), diameter (p less than 0.05), peak RBCV (p less than 0.05) and time to peak RBCV (p less than 0.01), as well as transcutaneous oximetry parameters (p less than 0.001) were significantly different between all groups and impaired with progression of ischaemia. However, a similar overlap between all groups was observed, except the supine TcpO2 parameter which separated F3/4 patients completely from the other groups. In all patients with critical limb ischaemia, dynamic parameters, such as peak RBCV (p less than 0.01) and time to peak RBCV (p less than 0.001), were significantly lower as compared to non-critically ischaemic patients, irrespective of an ankle pressure below or above a value of 50 mmHg, illustrating the additional value of microcirculatory assessment in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)