Skin Perfusion Pressure Measurement Research Articles

Assessing the Effects of Pulsed Electromagnetic Therapy on Painful Diabetic Distal Symmetric Peripheral Neuropathy: A Double-Blind Randomized Controlled Trial.

Significant complications of diabetes include pain and the loss of sensation in peripheral limbs. Pain management of diabetic symmetric peripheral neuropathy (DSPN) remains challenging. This study reports on utilizing pulsed electromagnetic field therapy (PEMF) to reduce pain and improve skin perfusion pressure (SPP) in subjects with DSPN. A randomized, sham-controlled, double-blind, clinical trial was conducted on subjects afflicted with foot pain associated with DSPN. Following informed consent, 182 subjects with diabetes and confirmed DSPN were entered into the trial for a period of 18 weeks. Subjects were randomized into active PEMF treatment or nonactive sham and instructed to treat to their feet for 30 minutes, twice daily and report daily pain scores. Some patients in the active arm experienced a transient low field strength notification (LFSN) due to improper pad placement during treatment. Skin perfusion pressure measurements were also collected at two and seven weeks to assess peripheral arterial disease effects via measurement of local microcirculatory flow and blood pressure. Patients in the active arm who did not receive an LFSN experienced a clinically significant 30% reduction in pain from baseline compared to sham (P < .05). Though not statistically significant, SPP in the active group trended toward improvement compared to sham. Pulsed electromagnetic field therapy appears effective as a nonpharmacological means for reduction of pain associated with diabetic peripheral neuropathy and holds promise for improvement of vascular physiology in microcirculatory dysfunction associated with diabetic peripheral arterial disease.

Mönckeberg's Medial Calcific Sclerosis Makes Traditional Arterial Doppler's Unreliable in High-Risk Patients with Diabetes.

To assess Mönckeberg's medial calcific sclerosis (MMCS) severity in patients with a diabetic foot infection. This was an analysis of 2 randomized clinical trials in which we evaluated the treatment of 233 patients admitted to the hospital for moderate and severe foot infections. Arterial calcification was defined as visible radiopaque arteries on foot and ankle radiographs, recorded as the most distal visible artery involved (toes, metatarsals, and ankle/hindfoot). Most subjects (57.1%, n = 133) had MMCS, with extension to toes in 79 (59.4%), to metatarsals in 32 (24.1%), and to ankle/hindfoot in 22 patients (16.5%). In 7 patients (5.2%) MMCS was solely seen in dorsalis pedis (DP) artery, in 13 patients (9.8%) in posterior tibialis (PT) artery, and in 113 patients (85.0%) MMCS was seen in both arteries. Only 29.2% (n = 68) of DP arteries and 34.8% (n = 81) of PT arteries were not compressible by Doppler. DP and PT arteries were not compressible more often in MMCS (DP 34.3% vs 20.4%, P = .02 and PT 43.1% vs 21.4%, P < .01), toe-brachial indices of ≥0.7 were significantly more common in people without MMCS (46.0% vs 67.4%, P < .01). In contrast, there were no differences in skin perfusion pressure measurements (>50 mmHg; 67.7% vs 68.0%, P = .96), waveforms (biphasic/triphasic 83.5% vs 77.0%, P = .22), and pulse volume recording (9.6 ± 3.3 vs 13.7 ± 36.0) between patients with and without MMCS. MMCS is common in patients with diabetic foot infections. MMCS is associated with noncompressible arterial Doppler studies and likely interferes with the accuracy of arterial Doppler studies.

Clinical utility of skin perfusion pressure measurement in diabetic foot wounds: An observational study.

The degree of blood vessel stenosis significantly influences diabetic foot treatment. This study aimed to investigate the association between computed tomography angiography (CTA) stenosis and skin perfusion pressure (SPP), which are noninvasive vascular assessments used to evaluate diabetic foot wounds. Forty patients who reported diabetic foot wounds between November 2016 and December 2017 were included in the study. SPPand CTA were performed to evaluate the blood flow, and the rate of decrease in wound size was measured for the wounds corresponding to Meggitt-Wagner grade 1 at the first evaluation and 4-week intervals. The P value of the association between the degree of CTA stenosis and the SPP value was 0.915, and the P value of the association between CTA stenosis and decreasing rate of wound size was .235. There was no statistically significant association between SPP and the decreasing rate of wound size according to the degree of CTA stenosis. The association between SPP value and the decreasing rate of wound size was statistically significant (P < .05). The decreasing rate in diabetic foot wound size was significantly associated with SPP but not with CTA stenosis.

Evaluation of a novel probe based on laser Doppler flowmetry and comparison with photo plethysmography for assessment of the skin perfusion pressure

This study aims to compare skin perfusion pressure measurements (SPP) at midfoot and below knee level performed with a novel laser Doppler flowmetry (LD) probe with a reference method based on photo plethysmography (PP). It includes 40 patients referred with known or suspected peripheral arterial disease. The SPP was performed with both devices. Blinded re-interpretation of the SPP measurements was carried out by three observers and a consensus quality score was provided for each measurement. SPP >40 mmHg was considered a clinically relevant cut-off. This study evaluates a total of 48 paired measurements of the midfoot and 54 below knee. The two methods agreed in overall diagnostic classification in 80 of 102 measurements (78%) with both methods showing SPP ≥40 mmHg in 21 cases, and both methods showing SPP <40 mmHg in 59 cases. Of the 22 participants with disagreement (22%) in overall classification, 15 had measurements within the range of 30-50 mmHg, and 7 with a clinically relevant disagreement with one device showing SPP <30 mmHg and the other ≥40 mmHg. Analysis of inter observer variation for the LD readings showed an intraclass correlation coefficient of 0.880 (95% CI: 0.807 to 0.929, p- value <0.05) at midfoot, and 0.933 (95% CI: 0.894 to 0.959, p-value <0.05) at below knee level. The novel probe based on LD showed good correlation with PP in absolute pressures, sufficient agreement in overall disease classification as well as good to excellent reliability in terms of inter observer variation.

Examination of a skin perfusion pressure measurement method for the detection of lower limb peripheral arterial disease in hemodialysis patients

Examination of a skin perfusion pressure measurement method for the detection of lower limb peripheral arterial disease in hemodialysis patients

Blood circulation in the fingers is aggravated after creating a vascular access for dialysis: assessment using skin perfusion pressure

Internal vascular shunts for haemodialysis can cause different complications. One of the most serious complications is steal syndrome, which can result in disturbed peripheral circulation causing finger necrosis and lead to amputation. Thus, prevention of these complications is important. Measurement of skin perfusion pressure (SPP) has been used in various clinical settings, including wound-healing management, and its usefulness has been increasingly unveiled. The present study was undertaken to evaluate changes in haemodynamics after internal shunt creation by measuring SPP of the thumb and the little finger before and after surgery in five patients undergoing shunt surgery using the radial artery and the cephalic vein. The study revealed average changes of −22.8 mmHg in thumb SPP. The change in the thumb was statistically significant (p < 0.05). If the effect of surgery and the threshold for wound healing are taken into account, the present results indicate the necessity to pay extra attention to fingers with extremely low preoperative SPP values. For the prevention of serious disturbances of peripheral circulation (e.g. steal syndrome), routine preoperative SPP measurement seems effective for screening of high-risk patients.

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 measured with a photo sensor in an air-filled plastic balloon: validity and reproducibility on the lower leg in normal subjects and patients suspected of obliterative arterial disease

An inflatable small plastic bag including a photo sensor was constructed for measurement of skin perfusion pressure avoiding the rim of the photo sensor over bony and tendineous surfaces of the tibia below the knee, at the ankle, and on the dorsal forefoot. Compression was obtained using a conical blood pressure cuff with continuous decrease from suprasystolic arm pressure. The validity of skin perfusion pressure with the new device was compared to that of isotope washout below the knee in normal subjects and in patients with an ischemic forefoot with acceptable agreement. The method had a high reproducibility within and between days in normal subjects. Compared to systolic arterial pressure measured using a strain gauge with a cuff on the ankle in normal subjects and patients with intermittent claudication the new device showed blood pressure in the skin closer to the diastolic pressure. The new pressure device thus had acceptable validity and reproducibility for estimation of the skin perfusion pressure and can be used on bony and tendineous sites on the lower limb in regions where critical wound healing is frequent, e.g. ankle and forefoot.

Vascular laboratory for the surgeon

The introduction of a noninvasive vascular laboratory emerged from the need for more accurate differential diagnosis, localization of disease, measurement of severity, and documentation of progression of occlusive arterial disease and efficacy of treatment. Plethysmographic and Doppler techniques have been the cornerstones in the development of noninvasive studies. Our vascular laboratory experience during 1977–1994 includes 36,573 examinations performed on 19,646 patients. Occlusive arterial disease of the lower limb was evaluated by 7408 complete lower limb examinations, of which 4939 included also a treadmill exercise test, 4539 toe pressure measurements, and 10,585 follow-up examinations. Altogether, 9102 miscellaneous examinations included ambulatory ECG and systemic blood pressure monitoring, assessment of limb viability by tcpO2, Laser Doppler flowmetry and skin perfusion pressure measurement, as well as upper extremity studies, among others. Although new techniques were introduced and tested during the years, the routine examinations have remained rather simple. Workup for claudication contains a structured questionnaire, segmental pressures and plethysmographic evaluation, and exercise test on treadmill, whereas diabetes and suspicion of CLI also necessitate toe pressures. Diabetic patients and those evaluated for aortic surgery also undergo ambulatory or stress test ECG monitoring. Carotid patients are noninvasively assessed by Duplex in the Radiological Department. A vascular laboratory managed by the vascular surgeon serves surgical needs well, as the tests can be tailor made to specifically answer relevant clinical questions.

Skin Perfusion Pressure Measurement to Assess Improvement in Peripheral Circulation after Arterial Reconstruction for Critical Limb Ischemia

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

Dynamic Skin Perfusion Pressure: A New Measure of Assessment for Wound Healing Capacity and Alternative Angiosome in Critical Limb Ischemia

Sir: In critical limb ischemia, circulatory assessment includes angiography, computed tomographic angiography, magnetic resonance angiography, ankle-brachial index, toe pressure, and Doppler ultrasonography, whereas wound assessment includes flat plate, magnetic resonance imaging, and the bleeding condition during débridement. Recently, we have used transcutaneous partial pressure of oxygen and/or skin perfusion pressure2,3 as objective tools to determine the skin circulation around the wound. For good wound healing, we have to identify the original angiosomes of the foot and find an alternative ischemic angiosome through arterial-to-arterial connection, because 15 percent of ischemic wounds cannot heal despite successful revascularization.1 The failure is considered to be caused by inadequate revascularization of the wound and/or inadequate wound care. Revascularization of the vessel directly supplying the ischemic angiosome is more successful than revascularization of the indirectly supplying one. We reported that skin perfusion pressure measurement would be useful for predicting wound healing in critical limb ischemia.3 We would like to propose dynamic skin perfusion pressure as a new assessment measure. We define dynamic skin perfusion pressure-1 as the measure of skin perfusion pressure when the anterior tibial artery is occluded manually; dynamic skin perfusion pressure-2 measures skin perfusion pressure when the posterior tibial artery is occluded manually (Fig. 1).Fig. 1.: The procedures of dynamic skin perfusion pressure measures. (Above) Dynamic skin perfusion pressure-1, which measures skin perfusion pressure when the anterior tibial artery is occluded manually. (Below) Dynamic skin perfusion pressure-2, which measure skin perfusion pressure when the posterior tibial artery is occluded manually.A 61-year-old man presented with gangrene (ankle-brachial index, immeasurable) on his right toes and heel at both sides (Fig. 2, above), and with diabetes mellitus. Angiography demonstrated that his right superficial femoral artery was occluded, the two tibial arteries showed chronic total occlusion, and the peroneal artery came out slowly. Skin perfusion pressure was 27 mmHg at the dorsum. We performed endovascular therapy for the superficial femoral artery with an 8.0 × 80-mm nitinol stent (Smart stent; Cordis, a Johnson & Johnson Company, Warren, N.J.) and balloon angioplasty for the anterior tibial artery. Skin perfusion pressure was slightly elevated to 31 mmHg at the dorsum and 47 mmHg at the forefoot. A dynamic skin perfusion pressure-1 measurement showed 25 mmHg at the dorsum and 39 mmHg at the forefoot. These findings demonstrated that the main flow of the sole was from the anterior tibial artery, and the angiosome of the sole was displaced to the anterior tibial artery area (i.e., his toes and medial heel might not have the capacity to heal). Thus, with additional endovascular therapy of bidirectional angioplasty,4 the posterior tibial artery was recanalized successfully from the origin to the pedal arch. Skin perfusion pressure was significantly improved to 68 mmHg at the dorsum, 66 mmHg at the forefoot, and 65 mmHg at the heel. A dynamic skin perfusion pressure-1 measurement showed 54 mmHg at the dorsum, 62 mmHg at the forefoot, and 65 mmHg at the heel. These findings demonstrated that the main flow of the sole was changed from the anterior tibial artery to the posterior tibial artery and that the angiosome of the sole was restored to its normal condition, which is originally the posterior tibial artery area. After 11 days, a modified transmetatarsal amputation5 was performed, and the wound was completely healed (Fig. 2, below). His postoperative course has not been eventful for 24 months and he has walked without the help of a stick. This modified procedure is useful for preserving the soft tissue between the metatarsal bones, including the vasculature complex with the muscles, the periostea, and the vessels except for tendons. The soft tissue can also provide cushioning during walking and preserve distal circulation after wound closure.Fig. 2.: Representative case before treatment (above) and 7 months after surgery (below).DISCLOSURE The authors have no financial interest to disclose. Hiroto Terashi, M.D., Ph.D. Department of Plastic Surgery Kobe University Hospital Kobe, Japan Takanori Iwayama, M.D. Department of Plastic Surgery National Hospital Organization Himeji Medical Center Himeji, Japan Osamu Iida, M.D. Department of Cardiovascular Division Kansai Rosai Hospital Amagasaki, Japan Ikuro Kitano, M.D., Ph.D. Yoriko Tsuji, M.D., Ph.D. Wound Healing Center/Vascular and Plastic Surgery Kobe, Japan

Measurement of Skin Perfusion Pressure in Hemodialyzed Patients: Association with Toe/Brachial Index

AbstractBACKGROUNDPatients with diabetes mellitus or renal failure may have calcified lower leg arteries, causing a falsely raised ankle/brachial index (ABI). In such cases, other combined noninvasive complementary observations may be useful. The purpose of this study was to investigate vascular complications of lower extremities in chronic hemodialyzed patients by measuring skin perfusion pressure (SPP) and the toe/brachial index (TBI).METHODSSixty‐five patients treated with regular hemodialysis were recruited. ABI, TBI, and SPP of the foot were measured in outpatient settings.RESULTSSPP was positively correlated with toe pressure (r = 0.560, p &lt; 0.001) and with TBI (r = 0.481, p &lt; 0.001). On the basis of the ABI results and diabetes status of the patients, 129 limbs were divided into 4 groups. For those in the normal ABI class (ABI &gt;0.9), SPP and TBI were decreased in the diabetic normal ABI group compared with those in the non‐diabetic normal ABI group.CONCLUSIONSThese findings not only support that diabetes is a risk factor for arteriosclerosis but also suggest that even in a normal ABI class, diabetic patients with end‐stage renal disease are already susceptible to arteriosclerotic assault of peripheral arterial complications. SPP measurement is a noninvasive, beneficial observation for lower extremity peripheral arterial disease in hemodialyzed patients at risk.

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

We studied whether the measurement of skin perfusion pressure (SPP) is useful for evaluating ischemic limbs and predicting wound healing. 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. 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. Our results suggest that measurement of SPP is an objective method for assessing the severity of peripheral arterial disease or for predicting wound healing.

Efficacy of Skin Perfusion Pressure Measurement in the Surgical Treatment for Critical Limb Ischemia

Efficacy of Skin Perfusion Pressure Measurement in the Surgical Treatment for Critical Limb Ischemia

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.

Examination of the Utility of Skin Perfusion Pressure Measurements in Diabetic Peripheral Vascular Disorders

Examination of the Utility of Skin Perfusion Pressure Measurements in Diabetic Peripheral Vascular Disorders

Skin perfusion pressure measurement is valuable in the diagnosis of critical limb ischemia.

Critical limb ischemia (CLI) is equated with a need for limb salvage. Arterial reconstruction and major amputation are the therapies ultimately available to such patients. We studied whether measurements of skin perfusion pressure (SPP) can be used to accurately identify those patients with CLI who require vascular reconstruction or major amputation and distinguish them from patients whose foot ulcer would heal with local wound care or minor amputation. Fifty-three patients with a total of 61 limbs with a nonhealing foot ulcer (age range, 47 to 88 years; mean, 70.8 +/- 9.8 years; 33 men, 20 women) who were referred to the Vascular Laboratory at Morristown Memorial Hospital for evaluation of arterial insufficiency were studied in a prospective, double-blinded fashion. Patients were included in the study if informed consent was obtained, and patients were excluded if there was uncontrolled sepsis or if they required guillotine amputation. The size and site of the foot ulcer was recorded. If gangrene was present, the location and extent was also noted. The pulses were examined and recorded, and the ankle-brachial index was determined for each limb. Measurements of SPP were made at the proximal margin of the ulcer in viable tissue (not in the bed of the ulcer). SPP measurements were made independent of the vascular surgeon's evaluation of the limb and were not part of his clinical decision regarding management of the foot ulcer. The SPP measurements were compared (Fischer's exact test) with the clinical decision for therapy (group I, arterial reconstruction or major amputation; or group II, wound debridement, minor amputation, or both). SPP was also compared with the outcome (ulcer healed or failed to heal) of therapy in group II. From contingency tables we calculated the sensitivity, specificity, positive and negative predictive values (PPV, NPV), and the overall accuracy of SPP measurement as a diagnostic test for critical limb ischemia. There was no difference in the size or location of foot ulcers between groups I and II, nor was there a difference in ulcer size or location between limbs that healed and did not heal in group II. The prevalence of diabetes was similar in all groups and subgroups. The ABI was not predictive of the need for reconstruction or major amputation nor the outcome of local therapy. SPP measurements identified 31 of 32 limbs diagnosed as having CLI by clinical evaluation (i.e., group I, those limbs that required vascular reconstruction or major amputation). Of those patients who were clinically assessed as not having CLI (group II), SPP measurements diagnosed 12 of the 14 limbs that did not heal as having CLI (PPV, 75%) and 11 of 15 limbs that did heal as not having CLI (NPV, 85%). The sensitivity of SPP less than 30 mm Hg as a diagnostic test of CLI was 85%, and the specificity was 73%. The overall diagnostic accuracy of SPP less than 30 mm Hg as a diagnostic test of critical limb ischemia was 79.3% (p < 0.002, Fischer's exact test). We conclude that SPP measurement is an objective, noninvasive method that can be used to diagnose critical limb ischemia with approximately 80% accuracy.

Vascular laboratory for the surgeon

The introduction of a noninvasive vascular laboratory emerged from the need for more accurate differential diagnosis, localization of disease, measurement of severity, and documentation of progression of occlusive arterial disease and efficacy of treatment. Plethysmographic and Doppler techniques have been the cornerstones in the development of noninvasive studies. Our vascular laboratory experience during 1977–1994 includes 36,573 examinations performed on 19,646 patients. Occlusive arterial disease of the lower limb was evaluated by 7408 complete lower limb examinations, of which 4939 included also a treadmill exercise test, 4539 toe pressure measurements, and 10,585 follow-up examinations. Altogether, 9102 miscellaneous examinations included ambulatory ECG and systemic blood pressure monitoring, assessment of limb viability by tcpO2, Laser Doppler flowmetry and skin perfusion pressure measurement, as well as upper extremity studies, among others. Although new techniques were introduced and tested during the years, the routine examinations have remained rather simple. Workup for claudication contains a structured questionnaire, segmental pressures and plethysmographic evaluation, and exercise test on treadmill, whereas diabetes and suspicion of CLI also necessitate toe pressures. Diabetic patients and those evaluated for aortic surgery also undergo ambulatory or stress test ECG monitoring. Carotid patients are noninvasively assessed by Duplex in the Radiological Department. A vascular laboratory managed by the vascular surgeon serves surgical needs well, as the tests can be tailor made to specifically answer relevant clinical questions.

The correlation between three methods of skin perfusion pressure measurement: Radionuclide washout, laser Doppler flow, and photoplethysmography

The most accurate measurement of skin perfusion pressure is made with use of radioisotopic clearance techniques. We compared the skin perfusion pressure using radioisotope to the skin perfusion pressure measured simultaneously by placing laser Doppler and photoplethysmography probes within a transparent polyvinylchloride plastic blood pressure cuff in 13 subjects. A new device, which was created for this experiment, consisted of a plastic bladder into which light-emitting probes can be placed, so that the pressure applied to the skin was transmitted by the surface of the bladder, rather than by the surface of a rigid probe. The cuff was inflated to a suprasystolic pressure over the intradermal injection site of technitium Tc 99m, then deflated in 10 mm Hg decrements at 3-minute intervals. The pressures at which radioisotope clearance began, at which microcirculatory flow was detected by laser Doppler, and at which deflection of the photoplethysmography (DC mode) output occurred, were recorded as the skin perfusion pressure. The range of radioisotopic determined skin perfusion pressure was 0 to 100; skin perfusion pressure-laser Doppler was 0 to 100; and skin perfusion pressure-photoplethysmography was 60 to 100, with 7 of 13 limbs demonstrating no clear deflection point and thus an unobtainable skin perfusion pressure-photoplethysmography reading. Linear regression revealed a coefficient of correlation of 0.991 for skin perfusion pressure when the radioisotopic and laser Doppler methods were compared. Our study is not in agreement with previous reports of the successful determination of skin perfusion pressure with use of photoplethysmography. This may be due to differences in our technique when compared with previous reports of skin perfusion pressure-photoplethysmography determination. We conclude that the determination of skin perfusion pressure with the laser Doppler is a simple bedside technique, easily measured in a noninvasive vascular laboratory, yielding results that correlate well with the determination of skin perfusion pressure by means of radioisotope clearance.

Criteria for reliable selection of the lowest level of amputation in peripheral vascular disease

To improve the chances for the amputee to become ambulatory the most distal level of amputation should be selected in patients with end-stage peripheral vascular disease. Physical examination alone provides insufficient information when amputation levels are closely related to areas with signs and symptoms of ischemia. In the present series of 85 lower extremity amputations the predictive values of clinical parameters and skin perfusion pressure measurements are assessed. The role of clinical judgment is clarified: the most distal level of amputation is to be selected by physical examination, but further information is required to assess the healing potential at the selected level. The presence of palpable pulses immediately above the selected level correlates well with primary wound healing (p less than 0.001, negative predictive value 100%). The absence of palpable pulses and angiographic patency scores are of no clinical value in amputation level selection. Skin perfusion pressure measurements were of excellent predictive value (p less than 0.001, positive predictive value 89%, negative predictive value 99%). According to these data a strategy is proposed for routine determination of the lowest level of amputation, where primary wound healing can be expected.