Rooke, Thom W.

Transcutaneous oxygen tension (TcPO 2 ) was measured according to a standard protocol in 43 limbs from 23 subjects, by use of oxygen-sensing electrodes attached to the chest (at a single site) or dorsum of the foot (at proximal and distal sites, located 1-2 cm apart). With the subjects supine, distal foot TcPO 2 differed from proximal by an average of ±7.4 mmHg, and in 80% of all limbs the differences were between -6 mmHg and + 15 mmHg. The two TcPO 2 's were subsequently combined to yield a single "average" value for each foot. TcPO 2 measurements were repeated twenty-four to forty-eight hours later; in the supine position the change in "average" foot TCPO 2 from the first to second measurement was ±6.9 mmHg, and in 80% of limbs the changes were between -11 mmHg and +9 mmHg. Similar reproducibility data were also obtained for ankle/brachial blood pressure indices (ABIs), chest TcPO 2 , and foot TcPO 2 during three minutes of leg elevation at 30 degrees. The authors conclude that: (1) TcPO 2 measurements from adjacent areas on the dorsum of the foot usually differ by 20-25% or less and (2) the short-term reproducibility of TcPO 2 between studies is comparable to that for ABIS.

In 37 patients (69 limbs) referred to Mayo Clinic's Vascular Center for possible venous valvular insufficiency in the lower limb, calf muscle pump function, calf compliance, and venous refilling times were measured by strain gauge plethysmography techniques. Patient limbs were separated into four categories based on 90% refilling time (T 90 ) following fifteen deep knee bends: normal (n =16), mild/moderate (n = 28), severe (n = 16), and edema of nonvenous origin (n=9). Pump function was assessed in actual pumping volumes (mL) and in percent pumping volumes (mL/100 mL), and was reduced in all noncontrol categories. Calf compliance was assessed in actual volume change (mL/mmHg) and in percent volume change (mL/100 mL/mmHg) and was increased in the severe reflux category. Ten study patients had 1 normal category limb and 1 reflux category limb. Paired analysis of these limbs showed pump function to be decreased and calf compliance to be increased in the diseased group limbs.

Plethysmography can be used to detect and assess venous incompetence in the lower extremities. The authors recently evaluated a new device designed for this purpose that uses strain gauges to determine changes in lower extremity cir cumference occurring with (and immediately after) exercise. The device plots a curve of volume against time for each limb and automatically calculates key values such as the volume of blood expelled from the lower limb veins during exercise and the time required for the veins to refill following exercise. The ap paratus was incorporated into their noninvasive vascular laboratory and used (along with other standard tests) to study patients referred for suspected venous incompetence. They observed the following: (1) A shortened postexercise refilling time ac curately identified limbs with venous incompetence. (2) The clinical severity of venous incompetence was inversely related to the refilling time. (3) Exercise- induced changes in lower extremity volume correlated well with simultaneously determined changes in venous pressure. (4) Valvular incompetence could be local ized to the deep or superficial veins based upon the improvement in refilling times seen following placement of elastic tourniquets around the lower limb. (5) The type of exercise performed (knee bends while the patient was standing versus ankle reflexes while sitting) had little effect on results. The authors conclude that exercise venous plethysmography is a useful noninvasive tool for assessing low er limb venous incompetence.

The authors evaluated the relationship between sympathetic nerve activity and transcutaneous oxygen tension (TcpO 2 ) in normal and ischemic lower extremities. Dorsal foot TcpO 2 was measured by using oxygen-sensing electrodes with surface temperatures of 42 ° C and 45°C; in theory, changes in sympathetic activity should affect vasomotor tone and TcpO 2 in skin beneath an electrode at 42 °C (submaximal vasodilation), but not at 45°C (maximal vasodilation). The vasodilation index (TcpO 2 at 42°C/TcpO 2 at 45°C) was created as an index of vasomotor tone (vasodilation index increases as tone decreases). In normal limbs (n=24) averages for TcpO 2 at 42°C, TcpO 2 at 45°C, and vasodilation index were 30.3 mmHg, 62.1 mmHg, and 0.47, respectively. In subjects (n=5) with quadriplegia and reduced sympathetic tone secondary to cervical cord trauma, TcpO 2 at 42 ° C and vasodilation index were increased (45.0 mmHg and 0.61); TcpO 2 at 45 ° C did not change. When normal subjects (n=7) were chilled for twenty minutes with a cooling blanket at 5 ° C (to increase sympathetic tone) average vasodilation index dropped from 0.50 to 0.29. Among ischemic limbs (n = 34) vasodilation index was highly variable (range: 0-0.77); in general, vasodilation index fell as the ischemia worsened. In a subset of patients with ischemic limbs, the vasodilation index increased after the limb was wrapped in a warm dressing (average vasodilation index=0.25without dressing, 0.37 with dressing). The authors conclude: (1) TcpO 2 can be used to assess the degree of vasomotor tone (and sympathetic activity) in skin; (2) tone generally increases as ischemia worsens; and (3) local warmth can improve cutaneous circulation in ischemic limbs.

Whether or not to screen asymptomatic members of the general public for various forms of vascular disease is a controversial issue with huge medical, social, and financial ramifications. This article reviews several criteria for determining the appropriateness of vascular screening, including: (1) is it possible to detect occult vascular disease `early'?; (2) what should we screen for, and how should we do it?; (3) who should be screened?; and (4) what standards for vascular screening should be set? While some of these controversies may ultimately be resolvable using an evidence-based approach, it is apparent that there are issues which will not be amenable to strict scientific analysis. Individualized approaches to screening will therefore remain the rule for the foreseeable future.

Previous results following subfascial endoscopic perforator vein surgery were reported to be worse in post-thrombotic syndrome than in limbs with primary valvular incompetence. This report comprises a larger patient cohort with longer follow-up. The goal of this study was to determine if subfascial endoscopic perforator vein surgery is justified in patients with postthrombotic venous insufficiency. The clinical data of 91 consecutive patients who underwent subfascial endoscopic perforator vein surgery with or without superficial reflux ablation over a 7-year period from May 1993 to June 2000 were retrospectively analyzed. Fifty-four females and 37 males (median age, 53 years; range, 20-77) underwent 103 subfascial endoscopic perforator vein surgery procedures. Forty-two limbs were classified as C6 (active ulcer), 34 as C5 (healed ulcer), and 24 as C4 (lipodermatosclerosis). Thirty procedures were performed in post-thrombotic limbs. Concomitant superficial reflux ablation was performed in 74 limbs (72%); saphenous vein stripping had been previously performed in 29 (28%). Deep venous incompetence was present in 89% of limbs; 13% had venous outflow obstruction on plethysmography. Cumulative ulcer healing in post-thrombotic limbs was not significantly different from limbs with primary valvular incompetence; 30-, 60-, and 90-day healing rates were 44%, 72%, and 72% vs 39%, 70%, and 87%, respectively (p = 0.35). On univariate analysis, the presence of ulcer greater than 2 cm in diameter was associated with delayed ulcer healing (p = 0.02). Cumulative ulcer recurrence in all limbs was 4%, 20%, and 27% at 1, 3, and 5 years, respectively. Ulcer recurrence in post-thrombotic limbs was higher than in limbs with primary valvular incompetence at 1, 3, and 5 years; 16%, 47%, and 56% vs 0%, 8%, and 15%, respectively (p = 0.001). Recurrent ulcers were small, superficial, and easier to heal. Clinical improvement was significant even in post-thrombotic limbs; median clinical score decreased from 9.5 to 3 (p=0.001), and median outcome score was +2 (mean 1.9; range, -I to 3). Median clinical score in patients with primary valvular incompetence improved from 6 to 1.5 (p = 0.0001). Subfascial endoscopic perforator vein surgery with superficial reflux ablation promoted ulcer healing, improved clinical outcome, and resulted in a low long-term ulcer recurrence rate in limbs with primary valvular incompetence. Despite good clinical outcome in post-thrombotic limbs, ulcer recurrence was high. These results imply that the role of subfascial endoscopic perforator vein surgery with superficial reflux ablation in patients with post-thrombotic limbs continues to be controversial.

Despite numerous advances in interventional radiology and vascular surgery, the clinician continues to be confronted with inoperable vascular disease. Previous studies have shown that ulceration associated with a transcutaneous oxygen pressure (tcPO 2 )of,20 mmHg is refractory to all attempts at healing. External pneumatic compression for the treatment of peripheral vascular disease has been available for several years, although there is a relative paucity of data regarding its role in clinical practice as well as its efficacy. The objective of this study was to examine the experience with circulator boot therapy in the treatment of ischemic ulcers in the absence of osteomyelitis, and specifically to determine whether such therapy can be of benefit in ischemic limb ulceration associated with a tcPO 2 of,20 mmHg. A retrospective chart review was undertaken of all patients with a lower limb ulcer who, in the absence of osteomyelitis, underwent circulator boot therapy at the Gonda Vascular Center. A total of 98 patients was identified. Two patients died within 1 month of commencing therapy and were not included in further analysis. The tcPO 2 data were unavailable in five patients. Outcome in the patient population was classified as favorable if (1) healing was achieved, (2) the ulcer decreased in size, or (3) the affected limb improved sufficiently to allow successful revascularization. An unfavorable outcome was one where a major amputation was performed or where the ulcer increased in size. Out of a total of 29 patients with a tcPO 2 ,20 mmHg at the area of ulceration, 19 had a favorable outcome following circulator boot therapy. Of the remaining 62 patients with a tcPO 2 .20 mmHg, 54 had a favorable outcome. Circulator boot therapy is associated with improved outcomes in limb ulceration due to peripheral vascular disease. Complete ulcer healing as well as preservation of the affected limb can be achieved in most cases.

Markers of inflammation are predictive of cardiovascular events but their association with atherosclerotic burden remains poorly defined. We hypothesized that markers of inflammation, including C-reactive protein (CRP), white blood cell (WBC) count, and lipoprotein-associated phospholipase A2 (Lp-PLA2), would be associated with the ankle-brachial index (ABI), a marker of atherosclerotic burden. Subjects were 247 patients referred for lower extremity arterial evaluation to the non-invasive vascular laboratory excluding those with active infection or lower extremity revascularization within the previous year. ABI was measured at two sites in both legs and the lowest of four measurements was used in the analyses. CRP was measured by a high-sensitivity immunoturbidimetric assay and Lp-PLA2 was measured by ELISA. The mean patient age was 68±11 years, and 54% were men. Mean ABI was 0.84-0.31 and 49% had an ABI < 0.9. Age, hypertension, fasting plasma glucose, and ‘ever’ smoking were independently associated with the ABI. Spearman correlation coefficients of inflammatory markers with the ABI were: CRP (r 1/4-0.15, p 1/4-0.02), WBC count (r 1/4-0.27, p 1/4-0.001), and Lp-PLA2 (r 1/4-0.09, p 1/4-0.21). In a multiple regression model that included conventional risk factors and statin use, CRP and WBC count were no longer significantly associated with ABI, whereas Lp-PLA2 was a borderline-significant predictor of lower ABI (p 1/4-0.05). These data indicate that CRP and WBC count are not independently associated with ABI, a marker of atherosclerotic burden in subjects referred for non-invasive lower extremity arterial evaluation. The association of Lp-PLA2 with ABI merits further study.