Hirohide Iwata

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.

A comparison of interface pressure and stiffness between elastic stockings and bandages

Objectives To compare the interface pressure during posture changes and exercise between elastic stockings and bandages. Methods Using a pressure transducer (air pack-type analyzer), the interface pressures associated with three different elastic stockings and three different elastic bandages were measured during supine resting, standing and exercise in 15 healthy volunteers. Results Short-stretch bandages showed a significantly higher static stiffness index value, which is defined as the pressure difference between lying and standing, than long-stretch bandages and short-stretch stockings (P < 0.001). Furthermore, short-stretch bandages showed a significantly greater pressure difference between muscle contraction and relaxation in both tip-toe and knee-bending exercises than long-stretch bandages and short-stretch stockings (P < 0.001). Conclusion Short-stretch bandages can be expected to have more pronounced benefits for augmenting muscle pump than long-stretch bandages and short-stretch stockings.

The prognosis of patients on hemodialysis with foot lesions.

OBJECTIVE Many studies have shown the high prevalence and incidence of peripheral arterial disease and the marked morbidity and mortality associated with peripheral arterial disease in hemodialysis patients. The purpose of this retrospective study was to clarify the probability of survival and limb salvage in patients with foot lesions and how to manage these patients. METHODS Data were collected in a retrospectively maintained database for 319 lower limbs with foot lesions in 234 hemodialysis patients treated in a university hospital between 1980 and 2011. Variances influencing survival and limb salvage were compared using log-rank tests and Cox regression analysis. These variables were examined using Kaplan-Meier analysis. Significant factors in bivariate analysis were included in a logistic regression model to determine independent predictors and the probability of failure. RESULTS The 234 patients (72% men) were a mean age of 65.4 years on admission, and 84% had diabetes. The mean duration of hemodialysis was 6.8 years. During the follow-up period, 171 patients (73%) died. The 1-, 3-, 5-, and 7-year survival rates were 65.2%, 35.5%, 23.4%, and 12.8%, respectively. According to Cox multivariate models, age at admission and ischemic changes on an electrocardiogram independently increased the risk of death (hazard ratios, 1.02 and 1.48, respectively). Conversely, hyperlipidemia independently decreased the risk of death (hazard ratio, 0.56). Critical limb ischemia was present in 247 limbs (77%). Arterial reconstruction was done in 88 limbs (28%), and 119 limbs (37%) required major amputation. The overall 1-, 3-, 5- and 7-year limb salvage rates were 68.9%, 57.2%, 53.8%, and 51.7 %, respectively. According to Cox multivariate models, patent arterial reconstruction and albumin independently decreased the risk of major amputation (hazard ratios, 0.265 and 0.392, respectively). CONCLUSIONS Hemodialysis patients with foot lesions have a poor prognosis, with high rates of mortality and amputation. Prompt assessments of the severity of systemic conditions, such as cardiac ischemia, and focal wound conditions, such as ischemia and infection, are necessary to treat hemodialysis patients with foot lesions.

Development of a device to determine the stiffness of elastic garments and bandages

Objective To evaluate the reliability of a newly developed stiffness-determining device, composed of a leg mannequin and air-pack type analyser, for measuring the interface pressure. Method The correlation of stiffness values obtained employing the Hohenstein method and this new method was investigated using 17 different brands of medical elastic compression stocking. Results A significant correlation in stiffness values using the two methods was obtained (P < 0.01). When this new method was applied to the bandages, the stiffness was significantly correlated with the initial pressure when assessing both short-stretch and long-stretch bandages. On the comparison of stiffness values between elastic stockings and bandages with the same initial pressure, the short-stretch bandages showed a predominantly higher value than long-stretch bandages and stockings (P < 0.01). Conclusion The reliability of this new method, which can be easily applied to not only elastic stockings but also elastic bandages, was verified. In clinical practice, the compression pressure should be selected in consideration of the prospective stiffness.

Interface pressure and stiffness in different combinations of compression material.

Objectives To compare the interface pressure and stiffness between various combinations of compression material. Methods Using a stiffness-determining device, the interface pressure and stiffness were determined in several combinations of five elastic stockings and two elastic bandages. Results In the double stockings system, the interface pressure increased significantly and the highest stiffness was observed in double short-stretch stockings. When short-stretch bandages were applied over either short- or long-stretch stockings, a significant increase in stiffness was observed at any initial pressure compared with the single use of short-stretch stockings. In double bandage systems, when short-stretch bandages were applied over either short- or long-stretch bandages, the stiffness increased significantly. When long-stretch bandages were used over short-stretch bandages, the stiffness decreased significantly. Conclusions The stiffness is changeable according to the combinations of material, such as double stockings, double bandages and the wearing of bandages over stockings. The use of short-stretch bandages as the outside layer produces the highest stiffness at a high initial pressure.

Abdominal aortic aneurysm surgery for octogenarians

PurposeTo define the indications for abdominal aortic aneurysm (AAA) surgery in octogenarians.MethodsWe reviewed septuagenarians and octogenarians with a nonspecific AAA diagnosed at our hospital between January, 1990 and June, 2006.ResultsAmong a total 628 patients seen, 306 were in their 70s (group A) and 108 were in their 80s or older (group B). The mortality rate associated with elective surgery was 1.9% in group A and 7.0% in group B. Of the survivors, 12 (5.7%) of 210 in group A and 8 (15.1%) of 53 in group B died within 2 years. Of the patients who did not undergo surgery, 8 of 53 in group A and 8 of 31 in group B had AAAs greater than 6 cm in diameter. The rupture-free rates of AAAs greater than 6 cm in diameter were 64% at 1 year and 0% at 4 years in group A, and 88% at 1 year and 26% at 3 years in group B. The rupture-free rates of AAAs smaller than 6 cm in diameter were 95% at 3 years and 85% at 5 years in group A, and 100% at 5 years in group B.ConclusionsWe concluded that AAAs over 6 cm in diameter were an appropriate indication for surgery in octogenarians.

Mid-term results of endovascular abdominal aortic aneurysm repair: Is it possible to predict sac shrinkage?

PurposeTo evaluate the mid-term results of endovascular repair of abdominal aortic aneurysms and to predict subsequent sac shrinkage.MethodsFrom December 2006 to April 2010, 114 abdominal aortic aneurysms were treated with stent grafts. The intraoperative sac pressure was measured by a microcatheter. Correlations between the diameter change and relevant factors were determined by a logistic regression analysis.ResultsStent grafts were deployed successfully in all patients. Type-2 endoleaks were noted in 25 patients (22%); there were no type-1 or type-3 endoleaks at discharge. The clinical success rate was 99%. The diameter was reduced in 40 patients (56%) but remained unchanged in 32 (44%). There were no aneurysms that increased in diameter. At 2 years after the repair the rate of cumulative survival was 87% and freedom from secondary intervention was 95%. The sac pressure index after stent grafting with a reduced diameter was 0.56 ± 0.11 and that of patients with an unchanged diameter was 0.52 ± 0.14. There were no significant differences between the two groups. Persistent type-2 endoleaks had a slightly negative effect on sac shrinkage (P = 0.052).ConclusionsThe mid-term results of endovascular aneurysm repair were satisfactory. Although it was difficult to predict the fate of a sac after stent grafting, persistent type-2 endoleaks were observed to have a slightly negative impact on sac shrinkage.

Comparison of stiffness and interface pressure during rest and exercise among various arm sleeves

Objectives To compare the interface pressure during rest and exercise among various kinds of arm sleeves. Methods The interface pressure underneath nine different arm sleeves was measured during 10 maximal opening and closing movements of fingers using a pressure transducer (Air Pack Type Analyser) in 16 healthy volunteers. Furthermore, in order to evaluate the characteristics of each arm sleeve, the extensibility, stiffness and thickness were determined in vitro by several apparatuses. Results There was a significant correlation between stiffness and extensibility. The stiffness was significantly correlated with the pressure difference between muscle contraction and relaxation during exercise. The higher the value of stiffness, the greater the pressure amplitude during exercise. Conclusion Short-stretch arm sleeves characterized with a high level stiffness, including thick round- and flat-knitted arm sleeves, are more beneficial for the augmentation of muscle pumping than long-stretch arm sleeves, in the same way as short-stretch bandages or stockings applied to the leg.

Interface Pressure and Stiffness of Various Elastic Stockings during Posture Changes and Exercise

The importance of measuring interface pressure and stiffness to characterize the elastic properties of materials has been stressed with regard to elastic stockings and elastic bandages. The objective of this study was to compare the pressure profiles of nine different elastic stockings and to quantify the effects of posture changes and exercise on compression. Using a pressure transducer (Air Pack Type Analyzer), the interface pressure associated with nine different elastic stockings was measured at level B1 during supine resting, standing, and exercise. The elastic stockings examined could be divided into two categories according to extensibility: short stretch (< 105% extensibility) and long stretch (> 105% extensibility). Short-stretch stockings include thick round-knitted stockings, firm round-knitted stockings, and flat-knitted stockings. Short-stretch stockings showed a higher peak working pressure and a larger pressure amplitude during exercise than long-stretch stockings. Short-stretch stockings can be expected to have more pronounced benefits for augmenting muscle pumping in the same way as short-stretch bandages. In selecting suitable elastic stockings for patients, the stiffness should be taken into account in addition to interface pressure.

Improvement of a three-dimensional measurement system for the evaluation of foot edema.

Background/aims: This study investigated the accuracy and usefulness of a newly improved three‐dimensional measurement system for measuring the volume and circumference at the foot as well as at the calf and ankle.