Biomedical subjects

T L Back

Publications and source records attributed to T L Back.

8 recordsLinked to original sources

PubMed1996

Transcutaneous oxygen (TcPO2) estimates probability of healing in the ischemic extremity.

The severity of arterial ischemia is a major variable affecting healing of extremity wounds. By relating risk of failure to severity of ischemia, the probability of wound healing may be stratified along with assessment of general medical risks. Transcutaneous oxygen tension (TcPO2) arterial segmental pressure (ASP), and arterial segmental indices (ASI) were obtained in 204 ischemic lower extremity sites; 63% of the sites were in patients with diabetes mellitus (DM), 11% in patients with chronic renal failure (CRF), and 37% in patients with neither DM nor CRF (ND). Wounds included 126 amputations and 78 gangrenous ulcerations of the foot or toes. Healing (n = 112) was defined as complete wound closure, without regard to the time required. Failure (n = 92) was defined by the requirement for either arterial reconstruction (n = 45) or proximal amputation (n = 47). Stepwise multiple regression analysis was used to assess the relative contribution of each measurement and to predict the probability of healing; TcP02 was superior to ASP and ASI in all categories. TcP02 was the only test meeting the P < 0.05 entry criteria modeled by the regression. An accuracy of 83% was achieved. However, when each test was evaluated by univariate analysis, ASP and ASI did meet the criteria for the ND group. However, the accuracy was 68 and 72%, respectively. Predictive accuracy of TcP02 was unaffected by DM or CRF. ASP and ASI were satisfactory in the ND group, although of slightly reduced accuracy. ASP and ASI were misleading and inaccurate in DM and CRF. Thus, of the noninvasive tests, TcP02 alone is sufficient for objective risk stratification of arterial ischemia in the lower extremity.

Blood Gas Monitoring, Transcutaneous↗

PubMed1996

Hemodynamic and clinical improvement after superficial vein ablation in primary combined venous insufficiency with ulceration.

PURPOSE: This study was undertaken to determine the degree of clinical and hemodynamic improvement after surgical ablation of incompetent superficial and perforator veins in limbs with combined deep and superficial venous incompetence manifested by chronic dermal ulceration. METHODS: Eleven limbs in 10 patients with class 5 or 6 venous insufficiency (ulceration) were assessed by CEAP (clinical, etiologic, anatomic, pathophysiologic) clinical scores, air plethysmography, color duplex ultrasonography, and phlebography (both ascending and descending). Surgical ablation of superficial and perforating veins was performed, followed by repeat clinical, air plethysmographic, and color duplex ultrasonographic examinations. RESULTS: All 11 limbs had combined deep and superficial vein reflux on the preoperative color duplex ultrasound scan. Clinical symptom scores decreased from 10 to 1.4 after operation. Postoperative air plethysmography demonstrated significant reduction in reflux as measured by the mean venous filling index, which decreased from 12 +/- 5 ml/sec to 2.7 +/- 1 ml/sec after surgery. Calf pump function was also significantly improved, with a mean ejection fraction that increased from 43% +/- 11 to 59% +/- 13 and mean residual volume fraction that decreased from 56% +/- 15 to 33% +/- 16. Each of these measures was significantly different from the preoperative value (p < 0.05). Similar improvement characterized subgroups of limbs with three or more incompetent deep segments (n = 6) or popliteal segment incompetence (n = 6). CONCLUSIONS: Superficial and perforating vein incompetence accounts for a substantial and correctable component of venous insufficiency in limbs with combined deep and superficial vein reflux and venous ulceration. These data indicate that surgical correction of this component significantly improves clinical symptoms and venous hemodynamics. Superficial and perforator ablation is an appropriate initial step in the management of combined deep and superficial venous incompetence.

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PubMed1995

Role of leukocyte activation in patients with venous stasis ulcers.

Alteration in leukocyte activation has been implicated as an etiological factor in the development of chronic venous stasis ulcers (CVSU). The purpose of this study was to determine differences in expression of cell surface activation markers on circulating leukocytes and systemic, soluble, serum cytokine levels between healthy controls and patients with CVSU. Twenty-three patients were separated into two groups. Group I consisted of 12 healthy, adult, age-matched male patients with no venous disease. Group II consisted of 11 adult male patients with CVSU who underwent air plethysmography (APG) and duplex scanning to determine the severity of venous insufficiency. All patients had measurements of systemic, serum-based, soluble IL-1 beta, IL-2, IL-6, TNF-alpha, and beta 2 microglobulin levels. Using fluorescence flow cytometry, we measured the percentage of lymphocytes (CD3), monocytes (CD14), and granulocytes (CD15) expressing various cell surface activation markers. By APG and duplex scan, all group II patients exhibited venous insufficiency, with a mean venous filling index of 6.9 +/- 3.9 sec. Relative to group I, group II patients demonstrated a decreased expression of the CD3+/DR+ (13.3 +/- 1.5, P < or = 0.01) and CD3+/CD38+ (31.1 +/- 2.1, P < or = 0.04) markers on T-lymphocytes and an increased expression of CD14+/CD38+ (99.6 +/- 0.2, P < or = 0.008) markers on monocytes. Circulating neutrophils showed no evidence of activation. In addition, a significant elevation in the T-helper to T-suppressor ratio (2.9 +/- 0.6, P < or = 0.0001) between groups I and II was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1995

Limited range of motion is a significant factor in venous ulceration.

PURPOSE: Calf muscle pump dysfunction is a recognized factor in chronic venous insufficiency (CVI). We investigated the hypothesis that limbs with CVI have a reduced ankle range of motion (ROM) that may be responsible for the poor calf pump function associated with venous ulceration. METHODS: Ankle ROM and calf pump function were assessed in 32 limbs of 26 adult men. Limbs were selected on the basis of clinical presentation: normal (n = 6 limbs), class 1 or 2 CVI with no history of ulceration (n = 9 limbs), class 3 CVI with healed ulceration (n = 9 limbs), and class 3 CVI with active ulceration (n = 8 limbs). ROM was determined by goniometry during maximal plantar flexion and dorsiflexion of the ankle. Calf pump function was determined by air plethysmographic measurement of ejection fraction (EF) and residual volume fraction (RVF). RESULTS: Ankle ROM was significantly (p < 0.05) reduced in each CVI group compared with age-matched control subjects, because of decreases in both plantar flexion and dorsiflexion. Calf pump function was significantly impaired (decreased EF and increased RVF) in ulcerated limbs. ROM was significantly correlated to EF and RVF. Impairment of ROM and calf pump function was associated with deterioration in the clinical classification of venous disease. CONCLUSIONS: Limbs with CVI have a limited ankle ROM that decreases with increasing severity of clinical symptoms. This decreased ROM is associated with, and may contribute to, poor calf pump function.

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PubMed1995

Diminished mononuclear cell function is associated with chronic venous insufficiency.

PURPOSE: With clinical progression of chronic venous insufficiency (CVI), dermal infiltration of mononuclear cells increases. Because these cells regulate chronic inflammatory responses and modulate wound healing, cellular dysfunction could explain alterations in wound healing with CVI. The purpose of this study was to determine whether monocytes in patients with CVI are dysfunctional. METHODS: Mononuclear cell function was measured as the degree of proliferation in response to a mitogenic challenge. Fifty patients were separated into four groups: group 1, 14 patients with normal limbs; group 2, 10 patients with class 2 CVI; group 3, 15 patients with active venous ulcers; group 4, 11 patients with healed venous ulcers and current evidence of lipodermatosclerosis. Duplex scanning and air plethysmography correlated with the clinical classification of CVI. Systemically circulating monocytes and lymphocytes were obtained by antecubital venipuncture from groups 1 to 4. Cells were cultured in the presence of staphylococcal enterotoxins A, B, C1, D, and E (mitogens) at 1, 8, 31, and 125 micrograms/well on the basis of previous dose-response experiments. Phytohemagglutinin (PHA), 5 micrograms/well, served as a control mitogen. The dose-response curves indicated that 8 micrograms/well elicited the greatest degree of cell proliferation. Proliferative responses at 8 micrograms/well were analyzed for statistical significance among groups 1 to 4. Comparisons among groups were performed by use of the nonparametric Mann Whitney U post tests and a one-tailed unpaired t test. Results were considered significant at p < or = 0.05. RESULTS: Proliferative responses to PHA indicate that lymphocytes and monocytes from patients with CVI are not globally depressed. However, patients in group 2 did not exhibit the same degree of proliferation to PHA as did groups 1, 3 and 4. Proliferative responses between groups 2 and 1 (44.38 +/- 43.9 vs 118.87 +/- 27.1, p < or = 0.05) and groups 2 and 3 (44.38 +/- 43.9 vs 105.95 +/- 60.99, p < or = 0.05) were significant. Challenges with staphylococcal enterotoxin A and B reveal significant diminution of proliferative responses in groups 2 (42.73 +/- 11.55, p < or = 0.05) and 3 (45.57 +/- 9.1, p < or = 0.05) and groups 3 (36.81 +/- 6.9, p < or = 0.05) and 4 (35.04 +/- 7.5, p < or = 0.05), compared with staphylococcal enterotoxin A controls (68.68 +/- 9.9) and staphylococcal enterotoxin B controls (66.25 +/- 13.56), respectively. A trend of diminished mononuclear cell function with progression of CVI was observed with staphylococcal enterotoxins B, C1, D, and E, strongly suggesting biologic significance. Furthermore, patients with lipodermatosclerosis uniformly exhibited the poorest proliferative responses. CONCLUSIONS: Deterioration of mononuclear cell function is associated with CVI. A trend of diminishing proliferative responses with clinical disease progression is observed and suggests biologic significance. The decreased capacity for mononuclear cell proliferation in response to various challenges may manifest itself clinically as poor and prolonged wound healing.

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PubMed1994

The significance of calf muscle pump function in venous ulceration.

PURPOSE: Patients with clinically evident chronic venous insufficiency were evaluated to relate the degree of insufficiency and calf muscle pump dysfunction to venous ulceration. METHODS: Sixty-nine limbs in 55 patients with chronic venous insufficiency by Society for Vascular Surgery/International Society for Cardiovascular Surgery Classification were compared in three groups: classes 1 and 2 with no history of ulceration (19 limbs); class 3 with healed ulceration (20 limbs); and class 3 with active ulcers (30 limbs). Air plethysmography measurements of outflow fraction, venous volume, venous filling time, venous filling index, ejection fraction, ejection volume, residual volume fraction, and residual volume were made. In 62 of the 69 limbs, color-flow duplex ultrasonography was used to determine the pattern of reflux. RESULTS: The outflow fraction was normal in 84%, 75%, and 77% of nonulcerated, healed, and ulcerated limbs. The venous filling index was abnormal in most limbs (nonulcerated 95%, healed 90%, ulcerated 98%) but not significantly different among groups. Differences in calf muscle pump function were significant. Ulcerated limbs had significantly poorer ejection fractions (p = 0.0002) and greater residual volume fractions (p = 0.0006) than nonulcerated or healed limbs. By ultrasonography, deep and superficial vein incompetence was present in most limbs and was not statistically different among groups. Although venous insufficiency was not measurably different among groups, limbs with active venous ulcers had significantly poorer calf muscle pump function than those with healed ulcers or with no history of ulceration. CONCLUSION: Venous insufficiency is necessary but not sufficient to cause ulceration, and a deficiency of the calf muscle pump is significant to the severity of venous ulceration.

Adult↗

PubMed1993

Refinements in the ultrasonic detection of popliteal vein reflux.

Color-flow and duplex ultrasonography were used to determine the optimal method for documenting venous valvular reflux. Popliteal veins were examined in 10 normal limbs and 11 limbs with clinical evidence of chronic venous insufficiency (CVI). Peak reflux velocity (spectral) and duration of reflux (spectral and color) were measured with the patient in supine and standing positions, with manual and pneumatic compression applied sequentially to thigh and calf. Manual and pneumatic compression produced equivalent reflux velocity and duration. In normal limbs peak reflux velocity was always less than 22 cm/sec, with a mean reverse flow duration of 0.3 sec +/- 0.03 (SEM). In limbs with CVI, reflux velocity varied widely among protocols. Reflux duration and velocity were greater in the supine position than in the standing position for both normal limbs and limbs with CVI (p < 0.04). Duration was significantly increased for thigh versus calf compression in normal limbs (p < 0.001) but decreased in limbs with CVI (p < 0.003). Methods that used thigh compression or supine position were less capable of discriminating normal limbs from limbs with CVI. Standing calf compression provided the greatest rates of sensitivity (91%), specificity (100%), and accuracy (95%). Compared with spectral Doppler scanning, color-flow ultrasonography produced a consistently shorter reflux duration (p < 0.001). In limbs with CVI with a mean spectral duration of 2.5 sec +/- 0.2 (SEM), mean color Doppler duration was 0.7 sec shorter. Our results demonstrate that popliteal vein incompetence is identified optimally by reflux duration after standing calf compression; adequate manual compression is sufficient to identify reflux; color-flow Doppler ultrasonography may underestimate reflux duration.

Adult↗

PubMedDate not supplied

Comparison of heated-probe laser Doppler and transcutaneous oxygen measurements for predicting outcome of ischemic wounds.

Transcutaneous oxygen (TcPO2) measurement has proven to be an accurate means of predicting healing of ischemic wounds. This study compares the ability of TcPO2 and laser Doppler, modified by the addition of a heated probe (LDHP), to assess wound outcome. TcPO2 and LDHP measurements were made at the same site for 80 wounds, which consisted of 51 amputations (25 above knee, 6 below knee, 20 forefoot) and 29 ulcerations. Healing was defined as complete wound closure. Failure to heal was defined by the necessity for proximal amputation in 22 wounds (6 amputations, 16 ulcers). Outcome criteria were chosen to maximize accuracy and either positive or negative predictive values. Criteria with the greatest accuracy and positive predictive value for wound healing were > or = 11 mmHg for TcPO2 and > or = 50 mv for LDHP range. Criteria with the most appropriate accuracy and negative predictive value for wound failure were < 5 mmHg for TcPO2 and < 35 mv LDHP range. All wounds whose LDHP range was < 35 mv failed to heal, whereas some wounds with a TcPO2 of 0-1 mmHg healed successfully. An absolute prediction of wound healing (100% specificity and negative predictive value) was offered when either LDHP range was > or = 125 mv or TcPO2 was > or = 33 mmHg, although accuracy of either measurement at this criteria was unacceptable for more general application. We conclude that TcPO2 or LDHP will assess wound outcome with similar overall accuracy, although each test may be better for predicting a specific outcome.

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