The role of air plethysmography in the diagnosis of chronic venous insufficiency

AbstractPurpose: The role of air plethysmography (APG) in the diagnosis of venous disease is not well defined. We conducted this study to investigate the value of APG in the diagnosis of chronic venous insufficiency and to determine its correlation with the clinical severity of disease and the anatomic distribution of reflux. Methods: We studied 186 lower extremities with duplex scanning and venography and measured the venous volume, venous filling index (VFI), ejection fraction, and residual volume fraction with APG. Limbs were categorized according to the Society for Vascular Surgery and International Society for Cardiovascular Surgery classification of clinical severity of disease and according to the anatomic distribution of valvular incompetence. Results: Sixty-one limbs had no evidence of disease (class 0), 60 limbs had mild disease (classes 1, 2, and 3), and 65 limbs had severe disease (classes 4, 5, and 6). According to the results of duplex scanning and venography, there was no evidence of reflux in 56 limbs. Isolated superficial venous reflux occurred in 52 limbs, and perforator reflux, alone or in conjunction with superficial reflux, occurred in 30. Deep reflux, with or without superficial reflux, was found in 25 limbs. Deep and perforator reflux, with or without superficial reflux, was found in 19 limbs. The VFI had a sensitivity of 80% and 99% positive predictive value for any type of reflux. The VFI was significantly different between groups of limbs with different clinical severities of disease or different types of reflux. The incidence of deep or perforator reflux in limbs with a normal VFI value was 7%, and it was 82% in limbs with a VFI of more than 5. Among 86 limbs with VFI values not corrected with use of a thigh tourniquet, 28% did not have evidence of deep or perforator reflux, and among 15 limbs with VFI values corrected with the use of a tourniquet, 33% had perforator reflux, deep reflux, or both. All APG parameters had low positive predictive values for severe disease or ulceration. The ejection fraction and residual volume fraction did not influence the clinical severity of disease, did not discriminate between types of reflux, and in combination with the VFI did not improve the predictive value of APG. Conclusions: The VFI measured by APG is an excellent predictor of venous reflux, provides an estimate of the clinical severity of disease, and at high levels predicts deep reflux, perforator reflux, or both. Correction of an abnormal VFI with a thigh tourniquet is an unreliable predictor of the absence of deep or perforator incompetence. The predictive value of APG for severe disease or ulceration is poor. The ejection fraction and residual volume fraction, individually or in combination with the VFI, add little to the diagnostic value of APG, and their routine performance may not be clinically justified. (J Vasc Surg 1998;27:660-70.

Beidler SK, Douillet CD, Berndt DF et al.Inflammatory cytokine levels in chronic venous insufficiency ulcer tissue before and after compression therapy. J Vasc Surg 49:1013-1020

Elevated inflammatory cytokine levels have been implicated in the pathogenesis of non-healing chronic venous insufficiency (CVI) ulcers. The goal of this study was to determine the protein levels of a wide range of inflammatory cytokines in untreated CVI ulcer tissue before and after 4 weeks of high-strength compression therapy. These levels were compared to cytokines present in healthy tissue. Thirty limbs with untreated CVI and leg ulceration received therapy for 4 weeks with sustained high-compression bandaging at an ambulatory wound center. Biopsies were obtained from healthy and ulcerated tissue before and after therapy. A multiplexed protein assay was used to measure multiple cytokines in a single sample. Patients were designated as rapid or delayed healers based on ulcer surface area change. The majority of pro-inflammatory cytokine protein levels were elevated in ulcer tissue compared to healthy tissue, and compression therapy significantly reduced these cytokines. TGF-beta1 was upregulated in ulcer tissue following compression therapy. Rapid healing ulcers had significantly higher levels of IL-1alpha, IL-1beta, IFN-gamma, IL-12p40, and granulocyte macrophage colony stimulating factor (GM-CSF) before compression therapy, and IL-1 Ra after therapy. IFN-gamma levels significantly decreased following therapy in the rapidly healing patients. CVI ulcer healing is associated with a pro-inflammatory environment prior to treatment that reflects metabolically active peri-wound tissue that has the potential to heal. Treatment with compression therapy results in healing that is coupled with reduced pro-inflammatory cytokine levels and higher levels of the anti-inflammatory cytokine IL-1 Ra

Prospective screening for postoperative deep venous thrombosis in patients undergoing infrainguinal revascularization

AbstractPurpose: The incidence of deep venous thrombosis (DVT) in patients undergoing infrainguinal bypass graft procedures has not been well documented, and the need for routine prophylaxis remains controversial. The purpose of this study was to prospectively evaluate the risk of postoperative DVT complicating infrainguinal revascularization. Methods: Seventy-four patients undergoing infrainguinal bypass graft procedures during a 12-month period were prospectively screened for DVT. Bilateral lower extremity venous duplex scan imaging was performed preoperatively and within 1 week and 6 weeks, postoperatively. Routine DVT prophylaxis was not used, with anticoagulation reserved for specific indications. Results: Of the 74 patients screened, three patients (4.1%) had DVT identified on preoperative venous duplex scan imaging and were excluded from the study. Of the remaining 71 patients enrolled, only two patients (2.8%) had postoperative DVT. Postoperative DVT was ipsilateral to the bypass graft extremity in both patients, with involvement of the peroneal vein in one patient and the femoral vein in the other. Although routine prophylaxis was not used, 18 of these patients (25%) were anticoagulated for other indications, with DVT occurring in one patient (5.6%). Of the remaining 53 patients who did not receive postoperative anticoagulation, only one patient (1.8%) had DVT. Conclusions: According to this prospective study, the risk of postoperative DVT in patients undergoing infrainguinal revascularization is low. Routine prophylaxis is not recommended, with postoperative anticoagulation reserved for specific indications. (J Vasc Surg 2000;32:669-75.

Recurrence of chronic venous ulcers on the basis of clinical, etiologic, anatomic, and pathophysiologic criteria and air plethysmography

AbstractIntroduction: Leg ulcers associated with chronic venous insufficiency (CVI) frequently recur after healing. The risk of recurrence has not been well defined for patients in different anatomic and hemodynamic groups. We reviewed the risk of ulcer recurrence on the basis of clinical, etiologic, anatomic, and pathophysiologic criteria and hemodynamic characteristics of the affected limb as assessed with air plethysmography (APG). Methods: Ninety-nine limbs with class 6 CVI were assessed clinically and with standing duplex ultrasound scanning and APG for the definition of clinical, etiologic, anatomic, and pathophysiologic criteria. Leg ulcers were treated with high-pressure compression protocols. Surgical correction of venous abnormalities was offered to patients with appropriate conditions. After ulcer healing, the limbs were placed in compressive garments and followed at 6-month intervals for ulcer recurrence. Results: The mean patient age was 54.3 years, and 46% of the patients were female. Corrective venous surgery was performed in 37 limbs. The mean follow-up time for all 99 limbs was 28 months. The ulcer recurrence rate with life table was 37% ± 6% at 3 years and 48% ± 10% at 5 years. The patients who underwent venous surgery had a significantly lower recurrence rate (27% ± 9% at 48 months) than did those patients who had not undergone surgery (67% ± 8% at 48 months; P =.005). The patients with deep venous insufficiency (DVI; n=51) had significantly higher recurrence rates (66% ± 8% at 48 months) than did the patients without DVI (n = 48; 29% ± 9% at 48 months; P =.006). This difference was significant even after accounting for the effects of surgery (P =.03).The hazard ratio of ulcer recurrence increases by 14% for every unit increase in the venous filling index (VFI; P =.001). This remains significant even after accounting for the effects of surgery (P =.001). The combination of DVI and a VFI of more than 4 mL/s yields a risk of ulcer recurrence of 43% ± 9% at 1 year and 60% ± 10% at 2 years. Conclusion: Leg ulcers associated with CVI have a high rate of recurrence. Ulcer recurrence is significantly increased in patients with DVI and in patients who do not have venous abnormalities corrected surgically. The VFI obtained from APG is useful in the prediction of increased risk for recurrence, particularly in association with anatomic data. (J Vasc Surg 2002;35:723-8.

Stochastic population growth in spatially heterogeneous environments

Classical ecological theory predicts that environmental stochasticity increases extinction risk by reducing the average per-capita growth rate of populations. To understand the interactive effects of environmental stochasticity, spatial heterogeneity, and dispersal on population growth, we study the following model for population abundances in $n$ patches: the conditional law of $X_{t+dt}$ given $X_t=x$ is such that when $dt$ is small the conditional mean of $X_{t+dt}^i-X_t^i$ is approximately $[x^i\mu_i+\sum_j(x^j D_{ji}-x^i D_{ij})]dt$, where $X_t^i$ and $\mu_i$ are the abundance and per capita growth rate in the $i$-th patch respectivly, and $D_{ij}$ is the dispersal rate from the $i$-th to the $j$-th patch, and the conditional covariance of $X_{t+dt}^i-X_t^i$ and $X_{t+dt}^j-X_t^j$ is approximately $x^i x^j \sigma_{ij}dt$. We show for such a spatially extended population that if $S_t=(X_t^1+...+X_t^n)$ is the total population abundance, then $Y_t=X_t/S_t$, the vector of patch proportions, converges in law to a random vector $Y_\infty$ as $t\to\infty$, and the stochastic growth rate $\lim_{t\to\infty}t^{-1}\log S_t$ equals the space-time average per-capita growth rate \sum_i\mu_i\E[Y_\infty^i] experienced by the population minus half of the space-time average temporal variation \E[\sum_{i,j}\sigma_{ij}Y_\infty^i Y_\infty^j] experienced by the population. We derive analytic results for the law of $Y_\infty$, find which choice of the dispersal mechanism $D$ produces an optimal stochastic growth rate for a freely dispersing population, and investigate the effect on the stochastic growth rate of constraints on dispersal rates. Our results provide fundamental insights into "ideal free" movement in the face of uncertainty, the persistence of coupled sink populations, the evolution of dispersal rates, and the single large or several small (SLOSS) debate in conservation biology.Comment: 47 pages, 4 figure

Sensory Communication

Contains table of contents on Section 2, an introduction, reports on eleven research projects and a list of publications.National Institutes of Health Grant 5 R01 DC00117National Institutes of Health Grant 5 R01 DC00270National Institutes of Health Contract 2 P01 DC00361National Institutes of Health Grant 5 R01 DC00100National Institutes of Health Contract 7 R29 DC00428National Institutes of Health Grant 2 R01 DC00126U.S. Air Force - Office of Scientific Research Grant AFOSR 90-0200U.S. Navy - Office of Naval Research Grant N00014-90-J-1935National Institutes of Health Grant 5 R29 DC00625U.S. Navy - Office of Naval Research Grant N00014-91-J-1454U.S. Navy - Office of Naval Research Grant N00014-92-J-181

Sensory Communication

Contains table of contents for Section 2, an introduction and reports on twelve research projects.National Institutes of Health Grant 5 R01 DC00117National Institutes of Health Contract 2 P01 DC00361National Institutes of Health Grant 5 R01 DC00126National Institutes of Health Grant R01-DC00270U.S. Air Force - Office of Scientific Research Contract AFOSR-90-0200National Institutes of Health Grant R29-DC00625U.S. Navy - Office of Naval Research Grant N00014-88-K-0604U.S. Navy - Office of Naval Research Grant N00014-91-J-1454U.S. Navy - Office of Naval Research Grant N00014-92-J-1814U.S. Navy - Naval Training Systems Center Contract N61339-93-M-1213U.S. Navy - Naval Training Systems Center Contract N61339-93-C-0055U.S. Navy - Naval Training Systems Center Contract N61339-93-C-0083U.S. Navy - Office of Naval Research Grant N00014-92-J-4005U.S. Navy - Office of Naval Research Grant N00014-93-1-119

Should ablative operations be used for bleeding esophageal varices?

To evaluate the long-term success of an ablative procedure for esophageal varices, the clinical results of 60 standardized, non-shunt (Womack) operations performed from 1953-1974 were reviewed. The overall operative mortality in this series was 35%. The 39 patients surviving operation have been followed from 5 to 21 years (mean: 13.3 years). Excluding operative mortality, the absolute 5-year survival rates for Child's classes A, B, and C patients were 100%, 63%, and 33%, respectively. The actuarial survival for all patients was 40% at 5 years, 24% at 10 years, and 15% at 15 years. Although the incidence of recurrent bleeding was 54%, clinical factors predictive for rebleeding could not be identified. A review of a collected series of other ablative operations, with and without esophageal transection, generally reveals unacceptable mortality and rebleeding rates. It is concluded that an ablative operation without esophageal transection should be used only in highly selected patients who do not have appropriate veins suitable for venous shunt