Gender differences in vascular access in hemodialysis patients in the United States: Developing strategies for improving access outcome

Background: Patients undergoing chronic hemodialysis (HD) require placement of permanent vascular access with the creation of an arteriovenous fistula (AVF), an arteriovenous prosthetic graft (AVG), or a tunneled central venous catheter. AVFs provide greater long-term patency, fewer complications, and lower infection rates than do either AVGs or catheters. Despite these advantages, women continue to be underrepresented among AVF patients, possibly because of concerns about smaller vascular diameters and higher rates of early primary fistula failure in female HD patients. The numerous clinical benefits of AVF suggest that a greater effort should be made to promote AVF placement in women.Objective: This review analyzes risk factors for AVF failure in women and describes clinical strategies to improve AVF utilization and success for female HD patients.Methods: English-language publications were identified through a MEDLINE database search from January 1997 to March 2007, using the search terms arteriovenous fistula, vascular access, hemodialysis, female, and gender. Reference lists of identified articles were also reviewed.Results: There are significant benefits to using AVFs instead of AVGs or catheters in HD patients: greater long-term fistula patency, superior flow rates, and fewer complications. Vascular anatomical differences between the sexes contribute to the underutilization of AVF in women. AVF placement rates can be improved if patients and staff are adequately educated and provided with the tools to facilitate AVF placement. Noninvasive preoperative screening is important to identify superior access sites in women. Intraoperative monitoring of blood flow is a reliable predictor of early radiocephalic AVF patency. Routine postoperative vascular monitoring may improve overall success with AVF, and exercise may improve vascular diameter and may be even more beneficial for women, who may have smaller preoperative veins.Conclusions: Concerns about smaller vascular diameters and reports of higher failure rates in women may prevent nephrologists and surgeons from considering AVF for female HD patients. The numerous advantages associated with AVF suggest that a greater effort should be made to increase its utilization in women. With appropriate motivation, care, and diligence by treating clinicians, the success of AVFs in women can approach the good results typically expected in men.     

A novel alternative placement site and technique for totally implantable vascular access ports in non‐human primates

Background Two novel approaches to implanting a central venous catheter port in non‐human primates (NHPs) using peripheral insertion are presented and compared. Methods Sixty vascular access port (VAP) implants were attempted in 52 NHPs by saphenous vein puncture (n = 20) or saphenous vein cutdown (n = 40). Results Fifty eight procedures were successful. Eighteen of 20 VAPs were successfully placed using saphenous vein puncture, and 40 of 40 using saphenous vein cutdown. There were no significant differences between procedures. Mean implantation times were similar between groups. At explant or study endpoint, all 58 VAPs were patent. Conclusions Vascular access port implantation by saphenous vein puncture or saphenous vein cutdown is safe and effective in NHPs. It is less invasive than conventional procedures, has fewer complications, provides outstanding patency, and reduces surgery time. Furthermore, it allows for cooperative in‐homecage VAP use, minimizing handling stress. We recommend these refined methods for long‐term vascular access in NHPs.     

Role of Far Infra-Red Therapy in Dialysis Arterio-Venous Fistula Maturation and Survival: Systematic Review and Meta-Analysis

Introduction

A well-functioning arteriovenous fistula (AVF) is the best modality for vascular access in patients with end-stage renal disease (ESRD) requiring haemodialysis (HD). However, AVFs’ main disadvantage is the high rate of maturation failure, with approximately one third (20%–50%) not maturing into useful access. This review examine the use of Far-Infra Red therapy in an attempt to enhance both primary (unassisted) and secondary (assisted) patency rates for AVF in dialysis and pre-dialysis patients.

Method

We performed an online search for observational studies and randomised controlled trials (RCTs) that evaluated FIR in patients with AVF. Eligible studies compared FIR with control treatment and reported at least one outcome measure relating to access survival. Primary patency and secondary patency rates were the main outcomes of interest.

Results

Four RCTs (666 patients) were included. Unassisted patency assessed in 610 patients, and was significantly better among those who received FIR (228/311) compared to (185/299) controls (pooled risk ratio of 1.23 [1.12–1.35], p = 0.00001). In addition, the two studies which reported secondary patency rates showed significant difference in favour of FIR therapy- 160/168 patients - compared to 140/163 controls (pooled risk ratio of 1.11 [1.04–1.19], p = 0.003).

Conclusion

FIR therapy may positively influence the complex process of AVF maturation improving both primary and secondary patency rates. However blinded RCTs performed by investigators with no commercial ties to FIR therapy technologies are needed.     

A high red blood cell distribution width predicts failure of arteriovenous fistula

In hemodialysis patients, a native arteriovenous fistula (AVF) is the preferred form of permanent vascular access. Despite recent improvements, vascular access dysfunction remains an important cause of morbidity in these patients. In this prospective observational cohort study, we evaluated potential risk factors for native AVF dysfunction. We included 68 patients with chronic renal disease stage 5 eligible for AVF construction at the Department of General and Vascular Surgery, Central Clinical Hospital Ministry of Internal Affairs, Warsaw, Poland. Patient characteristics and biochemical parameters associated with increased risk for AVF failure were identified using Cox proportional hazards models. Vessel biopsies were analyzed for inflammatory cells and potential associations with biochemical parameters. In multivariable analysis, independent predictors of AVF dysfunction were the number of white blood cells (hazard ratio [HR] 1.67; 95% confidence interval [CI] 1.24 to 2.25; p<0.001), monocyte number (HR 0.02; 95% CI 0.00 to 0.21; p?=?0.001), and red blood cell distribution width (RDW) (HR 1.44; 95% CI 1.17 to 1.78; p<0.001). RDW was the only significant factor in receiver operating characteristic curve analysis (area under the curve 0.644; CI 0.51 to 0.76; p?=?0.046). RDW>16.2% was associated with a significantly reduced AVF patency frequency 24 months after surgery. Immunohistochemical analysis revealed CD45-positive cells in the artery/vein of 39% of patients and CD68-positive cells in 37%. Patients with CD68-positive cells in the vessels had significantly higher white blood cell count. We conclude that RDW, a readily available laboratory value, is a novel prognostic marker for AVF failure. Further studies are warranted to establish the mechanistic link between high RDW and AVF failure.     

选择性冠状静脉动脉化搭桥术中不同移植物的应用疗效比较

目的:对比选择性冠状静脉动脉化(SCVBG)搭桥治疗弥漫性右冠状动脉狭窄病变中选择乳内动脉和大隐静脉作为桥血管的治疗效果。方法:选择2008年10月到2014年10月在我院行SCVBG搭桥的84例患者资料,其中选择大隐静脉作为桥血管进行冠状静脉动脉化搭桥患者46例(大隐静脉桥组),选择乳内动脉作为桥血管进行冠状静脉动脉化搭桥患者38例(乳内动脉桥组)。随访记录两组患者的生存情况、近期复查超声心动图、冠状动脉CTA及心绞痛复发率。结果:乳内动脉桥组患者总生存率(100%)明显高于大隐静脉桥组(82.6%)(P0.05)。乳内动脉桥组患者桥血管和心中静脉通畅率(100%)明显大于大隐静脉桥组(54.35%)(P0.05)。两组患者左心室射血分数(LVEF)较治疗前明显增加,左心室舒张期末内径(LVEDD)较治疗前明显减小(P0.05)。治疗后,乳内动脉桥组患者心绞痛复发率明显小于大隐静脉桥组(P0.05)。结论:SCVBG搭桥治疗弥漫性右冠状动脉狭窄病变中,选择乳内动脉桥效果优于大隐静脉桥,能明显提高桥血管和心中静脉通畅率,降低心绞痛复发率。     

A Retrospective Study of Preferable Alternative Route to Right Internal Jugular Vein for Placing Tunneled Dialysis Catheters: Right External Jugular Vein versus Left Internal Jugular Vein

Background

Right internal jugular vein (IJV) is a preferred access route for tunneled (cuffed) dialysis catheters (TDCs), and both right external jugular vein (EJV) and left IJV are alternative routes for patients in case the right IJV isn’t available for TDC placement. This retrospective study aimed to determine if a disparity exists between the two alternative routes in hemodialysis patients in terms of outcomes of TDCs.

Methods

49 hemodialysis patients who required TDCs through right EJV (n = 21) or left IJV (n = 28) as long-term vascular access were included in this study. The primary end point was cumulative catheter patency. Secondary end points include primary catheter patency, proportion of patients that never required urokinase and incidence of catheter-related bloodstream infections (CRBSI).

Results

A total of 20,870 catheter-days were evaluated and the median was 384 (interquartile range, 262–605) catheter-days. Fewer catheters were removed in the right EJV group than in the left IJV group (P = 0.007). Mean cumulative catheter patency was higher in the right EJV group compared with the left IJV group (P = 0.031). There was no significant difference between the two groups in the incidence of CRBSI, primary catheter patency or proportion of patients that never required urokinase use. Total indwell time of antecedent catheters was identified as an independent risk factor for cumulative catheter patency by Cox regression hazards test with an HR of 2.212 (95% CI, 1.363–3.588; p = 0.001).

Conclusions

Right EJV might be superior to left IJV as an alternative insertion route for TDC placement in hemodialysis patients whose right IJVs are unavailable.     

Wall shear stresses remain elevated in mature arteriovenous fistulas: a case study

Maintaining vascular access (VA) patency continues to be the greatest challenge for dialysis patients. VA dysfunction, primarily due to venous neointimal hyperplasia development and stenotic lesion formation, is mainly attributed to complex hemodynamics within the arteriovenous fistula (AVF). The effect of VA creation and the subsequent geometrical remodeling on the hemodynamics and shear forces within a mature patient-specific AVF is investigated. A 3D reconstructed geometry of a healthy vein and a fully mature patient-specific AVF was developed from a series of 2D magnetic resonance image scans. A previously validated thresholding technique for region segmentation and lumen cross section contour creation was conducted in MIMICS 10.01, allowing for the creation of a 3D reconstructed geometry. The healthy vein and AVF computational models were built, subdivided, and meshed in GAMBIT 2.3. The computational fluid dynamic (CFD) code FLUENT 6.3.2 (Fluent Inc., Lebanon, NH) was employed as the finite volume solver to determine the hemodynamics and shear forces within the healthy vein and patient-specific AVF. Geometrical alterations were evaluated and a CFD analysis was conducted. Substantial geometrical remodeling was observed, following VA creation with an increase in cross-sectional area, out of plane curvature (maximum angle of curvature in AVF=30?deg), and angle of blood flow entry. The mean flow velocity entering the vein of the AVF is dramatically increased. These factors result in complex three-dimensional hemodynamics within VA junction (VAJ) and efferent vein of the AVF. Complex flow patterns were observed and the maximum and mean wall shear stress (WSS) magnitudes are significantly elevated. Flow reversal was found within the VAJ and efferent vein. Extensive geometrical remodeling during AVF maturation does not restore physiological hemodynamics to the VAJ and venous conduit of the AVF, and high WSS and WSS gradients, and flow reversal persist. It is theorized that the vessel remodelling and the continued non-physiological hemodynamics within the AVF compound to result in stenotic lesion development.     

Regional and systemic hemodynamic responses following the creation of a murine arteriovenous fistula

The study of hemodynamic alterations following the creation of an arteriovenous fistula (AVF) is relevant to vascular adaptive responses and hemodialysis access dysfunction. This study examined such alterations in a murine AVF created by anastomosing the carotid artery to the jugular vein. AVF blood flow was markedly increased due to reduced AVF vascular resistance. Despite such markedly increased basal blood flow, AVF blood flow further increased in response to acetylcholine. This AVF model exhibited increased cardiac output and decreased systemic vascular resistance; the kidney, in contrast, exhibited decreased blood flow and increased vascular resistance. Augmentation in AVF blood flow was attended by increased arterial heme oxygenase-1 (HO-1) mRNA and protein expression, the latter localized to smooth muscle cells of the AVF artery; AVF blood flow was substantially reduced in HO-1(-/-) mice compared with HO-1(+/+) mice. Finally, in a murine model of a representative disease known to exhibit impaired hemodynamic responses (sickle cell disease), the creation of an AVF was attended by decreased AVF flow and impaired AVF function. We conclude that this AVF model exhibits markedly increased AVF blood flow, a vasodilatory reserve capacity, increased cardiac output, decreased renal blood flow, and a dependency on intact hemodynamic responses, in general, and HO-1 expression, in particular, in achieving and maintaining AVF blood flow. We suggest that these findings support the utility of this model in investigating the basis for and the consequences of hemodynamic stress, including shear stress, and the pathobiology of hemodialysis AVF dysfunction.     

Manual pressure distension of the human saphenous vein changes its biomechanical properties-implication for coronary artery bypass grafting

Patency rates of saphenous vein grafts following coronary artery bypass grafting (CABG) depend on multiple factors. Information regarding the impact of biomechanical properties of vein grafts on patency rates is not available. The objective of the present study was to evaluate whether uncontrolled manual pressure distension during routine preparation of the saphenous vein in CABG-induced changes in the biomechanical properties of the vein. The morphometric and stress-strain properties were studied in isolated segments of the saphenous vein from 12 patients undergoing elective CABG. Six segments were manually distended without pressure control and six were not distended. The mechanical test was performed as a ramp inflation using syringe pump. The vein dimensions were obtained from digitised images at different pressures as well as at the no-load and zero-stress states. The circumferences, the wall and lumen area, the wall thickness, and the outer diameter as function of the applied pressure were largest in the segments with uncontrolled manual distension compared to those without distension (P<0.05). The opening angle and the absolute value of the residual strains were lower (P<0.01) and the circumferential stress-strain curve shifted to the left, indicating the wall became stiffer with uncontrolled manual distension compared to those without distension (P<0.05). In conclusion, manual pressure distension changed the morphometric and biomechanical properties of the saphenous vein. The perspective is that studies on biomechanical properties on the saphenous vein may guide surgeons how to handle graft material without causing major changes of the biomechanical properties during harvesting and preparation.     

Predictive Factors of Late Venous Aortocoronary Graft Failure: Ultrastructural Studies

Background

Venous aortocoronary graft arterialization may precede a preterm occlusion in some coronary artery bypass grafting (CABG) patients. The aim of the present study was to identify ultrastructural variations in the saphenous vein wall that may have an impact on the development of venous graft disease in CABG patients.

Methods

The study involved 365 consecutive patients with a mean age of 62.9±9.4 years who underwent isolated CABG. The thickness and area of the whole venous wall, the tunica intima, the tunica media and the adventitia and the number and shape (length, thickness and length/thickness ratio) of the nuclei in the medial smooth muscle cells nuclei in the distal saphenous vein segments were evaluated by ultrastructural studies. Patients were followed up for 41 to 50 months (mean 45.1±5.1). Saphenous vein graft patency was assessed by follow-up coronary angiography. Logistic regression models were used to identify independent risk factors for late graft failure.

Results

In 71 patients significant lesions in the saphenous vein grafts were observed. The whole venous wall thickness (437.5 µm vs. 405.5 µm), tunica media thickness (257.2 µm vs. 211.5 µm), whole venous wall area (2.23 mm² vs. 2.02 mm²) and tunica media area (1.09 mm² vs. 0.93 mm²) were significantly larger for this group of patients than for those without graft disease. In the latter group more elongated smooth muscle cell nuclei (higher length/thickness ratio) were found in the tunica media of the saphenous vein segments. Thickening of the saphenous vein tunica media and chunky smooth muscle cell nuclei were identified as independent risk factors for graft disease development.

Conclusions

Saphenous vein tunica media hypertrophy (resulting in wall thickening) and chunky smooth muscle cell nuclei might predict the development of venous graft disease.     

经膝下途径导管直接溶栓治疗混合型下肢深静脉血栓形成

目的:评价经膝下(Below the Knee, BTK)途径导管直接溶栓(Catheter-Directed Thrombolysis, CDT)治疗混合型下肢深静脉血栓形成(Deep Vein Thrombosis, DVT)的安全性和有效性。方法:回顾性分析2013年1月至2017年10月于徐州市肿瘤医院介入科接受经BTK途径CDT治疗的38例急性混合型DVT患者临床资料,其中男性患者26例,女性患者12例,年龄54±11岁。结果:技术成功率为100%。经小隐静脉穿刺途径28例,小隐静脉切开途径4例,胫后静脉切开途径4例,胫后静脉穿刺途径2例。行CDT前,所有患者均接受临时可回收滤器置入,并于术后2周内取出。36名患者DVT血栓溶解成功(Ⅱ和Ⅲ级)。2名未获得血栓溶解成功的患者,从症状发生到CDT时间均大于10天。对13例患者(左侧10例,右侧3例)进行髂静脉球囊扩张和支架植入。围手术期出现切口渗血4例,切开部位麻木5例,没有新发肺栓塞和大出血发等主要并发症。平均随访时间为2年(1个月-4年),28例患者超过1.5年。2例患者由于未服用华法林而出现反复髂股DVT。随访期间通畅率和PTS率分别为81.6%(31/38)和31.6%(12/38)。结论:采用经BTK途径行CDT治疗混合型DVT是安全有效的,围手术期及随访期间结果满意,是一种值得推广的方法。     

The role of the large superficial vein in survival of proximally based versus distally based sural veno-neuro-fasciocutaneous flaps in a rabbit model

A sural veno-neuro-fasciocutaneous flap in the New Zealand White rabbit was developed, and the role of the large subcutaneous lesser saphenous vein was investigated in proximally based versus distally based flaps. Retrograde dye injection showed that the lesser saphenous vein in rabbits has many valves with strong resistance against reflux. Twenty rabbits were randomly allocated into four groups of 10 flaps each. Group I consisted of proximally based flaps with the lesser saphenous vein intact (outflow) in the veno-neuro-adipofascial pedicle. Group II also consisted of proximally based flaps but the lesser saphenous vein was ligated at 1 cm proximal to the pedicle. Group III consisted of distally based flaps with the lesser saphenous vein intact (inflow) in the veno-neuro-adipofascial pedicle. Group IV also consisted of distally based flaps, but the lesser saphenous vein was ligated at 1 cm distal to the pedicle. The results showed that the mean flap survival area in group I (88.8 percent) was statistically higher than that in group II (62.6 percent, p < 0.001), and was higher in group IV (55.5 percent) than in group III (22.7 percent, p < 0.01). However, group II and group IV had no significant difference (p > 0.05). This experiment demonstrated that flap viability is determined by its intrinsic vascularization, both arterial and venous. The large superficial subcutaneous vein has a positive role (venous outflow) in proximally based flaps but a negative role (venous inflow) in distally based flaps. If the effect of the large subcutaneous vein is excluded, distally based flaps are not inherently inferior to proximally based flaps.     

Computational Study of Anastomosis Angle of Arteriovenous Fistula for Hemodialysis

Arteriovenous fistula (AVF) is the endorsed method of vascular access for hemodialysis in end-stage renal disease (ESRD). However, more than 60% of AVF fail to mature for hemodialysis. Intimal hyperplasia leads to stenosis is the primary cause of fistula failure. Wall shear stress (WSS) is one of the important parameters that enact a crucial role in building of intimal hyperplasia. The prime purpose of this research work is to investigate the effect of anastomosis angle on WSS, pressure drop, venous outflow rate and identify the optimal angle of anastomosis of AVF, so that it helps to standardize the surgical technique. In this research work, three-dimensional idealized geometries of end-to-side type AVF for the four different angles of anastomosis are created. Numerical simulation performed using incompressible, Newtonian blood to calculate the WSS, blood flow rate at the distal end of the vein and pressure drop across the anastomosis for the three arterial inflow 350, 500 and 900 ml/min. For all three arterial inflow, the WSS is high at 75° compared to other angles and it is less at 60°. The WSS at 45° and 90° are moderate. The venous outflow is increasing with the increase in arterial inflow condition for all anastomosis angles except for 45°. The outflow rate at distal venous end is highest, 344.85 ml/min at 45° for 500 ml/min arterial inflow. Pressure drop high at 45° and lowest at 90°. The intensity of disturbed flow and recirculation zone was observed at the area of anastomosis and it is high at 75°. From the results and observations, it can be concluded that 45° angle is the best choice for the anastomosis of AVF. This finding will standardize the surgical technique and subsequently, it will help to mature the AVF early and for a long time.     

Thrombin-Anti-Thrombin Levels and Patency of Arterio-Venous Fistula in Patients Undergoing Haemodialysis Compared to Healthy Volunteers: A Prospective Analysis

Background

Patients on haemodialysis (HD) are at an increased risk of sustaining thrombotic events especially to their vascular access which is essential for maintenance of HD.

Objectives

To assess whether 1) markers of coagulation, fibrinolysis or endothelial activation are increased in patients on HD compared to controls and 2) if measurement of any of these factors could help to identify patients at increased risk of arteriovenous (AVF) access occlusion.

Patients/Methods

Venous blood samples were taken from 70 patients immediately before a session of HD and from 78 resting healthy volunteers. Thrombin-antithrombin (TAT), D-dimer, von Willebrand factor (vWF), plasminogen activator inhibitor-1 antigen (PAI-1) and soluble p-selectin were measured by ELISA. C-reactive protein (hsCRP) was measured by an immunonephelometric kinetic assay. Determination of the patency of the AVF was based upon international standards and was prospectively followed up for a minimum of four years or until the AVF was non-functioning.

Results

A total of 70 patients were studied with a median follow-up of 740 days (range 72-1788 days). TAT, D-dimer, vWF, p-selectin and hsCRP were elevated in patients on HD compared with controls. At one year follow-up, primary patency was 66% (46 patients). In multivariate analysis TAT was inversely associated with primary assisted patency (r= -0.250, p= 0.044) and secondary patency (r = -0.267, p= 0.031).

Conclusions

The novel finding of this study is that in patients on haemodialysis, TAT levels were increased and inversely correlated with primary assisted patency and secondary patency. Further evaluation is required into the possible role of TAT as a biomarker of AVF occlusion.     

End-to-end versus end-to-side microvascular anastomosis patency in experimental venous repairs

In this experimental study, venous end-to-end and end-to-side microvascular anastomoses in similar and diameter-discrepant vessels were compared. In 50 rats, end-to-end microvascular repair of the divided epigastric vein and end-to-side repair of the epigastric vein into the femoral vein showed 5-day patency rates of 75 and 88 percent, respectively. These data are not statistically different. In 20 rats, microvascular repair of end epigastric to end femoral veins (size discrepant) and end epigastric to side femoral veins showed 5-day patency rates of 50 and 85 percent, respectively. These data are statistically different (p less than 0.05). We conclude from these experimental data that end-to-side venous repairs may be useful in lowering the anastomosis thrombosis rate seen when size-discrepant veins are repaired.     

VARICOSE VEINS—A Practical Approach to Treatment

Adequate treatment of varicose veins requires thorough mapping of perforating veins, communicating veins and “blow out” areas. Combined ligations, stripping and injection of sclerotic substances after operation is the most effective regimen of therapy.The technique of stripping is facilitated by isolating the saphenous vein at the ankle, inserting the stripper from below upward, then making a transverse groin incision over the palpable stripper. The tip of the stripper should be twice the diameter of the vein to be removed. Stripping should be done with the patient in the Trendelenburg position.All patients must be examined at regular intervals after operation and injection of sclerosing material carried out as necessary.     

尿毒症血液透析患者血清Lp-PLA2、FGF-23与自体动静脉内瘘成熟不良的关系研究

摘要 目的：探讨尿毒症血液透析患者血清脂蛋白相关磷脂酶A2（Lp-PLA2）、成纤维细胞生长因子-23（FGF-23）与自体动静脉内瘘（AVF）成熟不良的关系。方法：选取2021年2月～2022年12月联勤保障部队第908医院肾内科收治的170例接受血液透析的尿毒症患者,根据AVF成熟情况分为成熟不良组57例和成熟组113例。采用酶联免疫吸附法检测血清Lp-PLA2、FGF-23水平。通过多因素Logistic回归分析尿毒症血液透析患者AVF成熟不良的影响因素,受试者工作特征（ROC）曲线分析血清Lp-PLA2、FGF-23水平对尿毒症血液透析患者AVF成熟不良的预测效能。结果：成熟不良组血清Lp-PLA2、FGF-23水平高于成熟组（P＜0.05）。多因素Logistic回归分析显示,血磷、低密度脂蛋白胆固醇（LDL-C）、Lp-PLA2、FGF-23升高为尿毒症血液透析患者AVF成熟不良的独立危险因素（P＜0.05）。ROC曲线分析显示,血清Lp-PLA2、FGF-23水平单独和联合预测尿毒症血液透析患者AVF成熟不良的曲线下面积（AUC）分别为0.725、0.763、0.822,血清Lp-PLA2、FGF-23水平联合预测的AUC最大。结论：尿毒症血液透析患者血清Lp-PLA2、FGF-23水平升高与AVF成熟不良独立相关,血清Lp-PLA2、FGF-23水平联合对AVF成熟不良的预测效能良好。     

Influence of smoking and plasma factors on patency of femoropopliteal vein grafts.

OBJECTIVE--To determine the effects of smoking, plasma lipids, lipoproteins, apolipoproteins, and fibrinogen on the patency of saphenous vein femoropopliteal bypass grafts at one year. DESIGN--Prospective study of patients with saphenous vein femoropopliteal bypass grafts entered into a multicentre trial. SETTING--Surgical wards, outpatient clinics, and home visits coordinated by two tertiary referral centres in London and Birmingham. PATIENTS--157 Patients (mean age 66.6 (SD 8.2) years), 113 with patent grafts and 44 with occluded grafts one year after bypass. MAIN OUTCOME MEASURE--Cumulative percentage patency at one year. RESULTS--Markers for smoking (blood carboxyhaemoglobin concentration (p less than 0.05) and plasma thiocyanate concentration (p less than 0.01) and plasma concentrations of fibrinogen (p less than 0.001) and apolipoproteins AI (p less than 0.04) and (a) (p less than 0.05) were significantly higher in patients with occluded grafts. Serum cholesterol concentrations were significantly higher in patients with grafts that remained patent one year after bypass (p less than 0.005). Analysis of the smoking markers indicated that a quarter of patients (40) were untruthful in their claims to have stopped smoking. Based on smoking markers, patency of grafts in smokers was significantly lower at one year by life table analysis than in non-smokers (63% v 84%, p less than 0.02). Patency was significantly higher by life table analysis in patients with a plasma fibrinogen concentration below the median than in those with a concentration above (90% v 57%, p less than 0.0002). Surprisingly, increased plasma low density lipoprotein cholesterol concentration was significantly associated with improved patency at one year (85%) at values above the median compared with patency (only 68%) at values in the lower half of the range (p less than 0.02). CONCLUSIONS--Plasma fibrinogen concentration was the most important variable predicting graft occlusion, followed by smoking markers. A more forceful approach is needed to stop patients smoking; therapeutic measures to improve patency of vein grafts should focus on decreasing plasma fibrinogen concentration rather than serum cholesterol concentration.     

Peritoneal Dialysis in Chronic Renal Failure

The long-term results of intermittent peritoneal dialysis in long-term treatment of renal disease have yet to equal those of intermittent hemodialysis. However, further exploration and refinement of this technique is justified.Performed in acute stages of disease, both peritoneal dialysis and hemodialysis relieve the symptoms of uremia and specifically “buy time” for the patient so that proper medical or surgical therapy may be instituted. In acute situations, peritoneal dialysis is the procedure of choice, and is an important adjunct to more conventional treatment for chronic renal disease. It may be useful sometimes even in chronically hemodialyzed patients—for example, when the hemodialysis cannula for one reason or another is inaccessible because of clots, replacement, or infection. It is especially valuable when the hemorrhagic complications of uremia contraindicate hemodialysis treatment.Its use in chronic uremia remains sharply limited in time, but for brief periods chronic peritoneal dialysis appears to be a reasonably satisfactory means of prolonging life while awaiting homotransplant or decision for maintenance hemodialysis therapy.     

A simplified method for metabolic studies in conscious swine

Reliable short-term blood access in conscious swine was provided by implanting multiple silastic catheters. Catheters were inserted into the aorta, hepatic vein, portal vein, and inferior vena cava through a midline laparotomy incision. Multiple catheters also were placed into the external jugular vein through a separate cervical incision. Catheter patency rates for blood withdrawal on the sixth post-operative day were: arterial 100%, hepatic 91%, portal 86%, inferior vena cava 71%. No animal had major wound or catheter infection on the seventh post-operative day. The methods described allow metabolic studies, including measurements of splanchnic blood flow, to be carried out either acutely or for up to at least 7 days post-operatively.