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Restricted accessResearch articleFirst published April, 2002pp. 47-48
Restricted accessResearch articleFirst published April, 2002pp. 49-57To retrospectively review the complications reported during percutaneous thrombectomy procedures performed on polytetrafluoroethylene hemodialysis grafts.
A retrospective review revealed that 935 percutaneous thrombectomy procedures were performed at our institution between January 1993 and June 2001. The type and number of procedures include: Arrow PTD (527), pulse-spray with urokinase (240), Amplatz Thrombectomy Device (96), AngioJet (17), Oasis (15), Hydrolyser (10), Endovac (7), Lyse and Wait (7), Thrombex (6), Cragg brush (6), Castaneda brush (4). Complications were reported to have occurred in 31 patients. The radiology reports and medical records of these patients were reviewed.
The overall complication rate was 3.3%. The type and number of complications included: rupture of a vein during angioplasty (13), severe cardiopulmonary distress (4), arterial emboli (4), rigors related to urokinase (3), minor bleeding (2), hypoxia with chest pain (2), other assorted complications (3). There was one death resulting from a fall from the angiography table immediately following the procedure. There were 12 minor complications, requiring minimal treatment, and 19 major complications that altered the course of the procedure or treatment of the patient.
The most common complication was angioplasty-induced rupture of the vein or graft. The most severe complications occurred immediately following dislodgement of the arterial plug and were likely due to acute pulmonary embolization.
Restricted accessResearch articleFirst published April, 2002pp. 58-63Vascular access stenosis and thrombosis is one of the key problems for hemodialysis patients. Prospective monitoring of static venous dialysis pressures can be applied to detect outflow stenoses in a vascular access. However, the location of stenoses within the access may influence the diagnostic value of venous pressure measurements. Whereas a decrease in access flow occurs with all types of stenosis, strictures within the arterial anastomosis or between arterial and venous dialysis needle cannot be detected with venous pressure measurements alone.
A new approach is discussed, which bases on the improved measurement of static venous and arterial extracorporeal pressures. Extracorporeal pressure at zero blood flow depends on both the position of the heart relative to the extracorporeal blood circuit and the vertical offset between access site and fluid level in the bloodline. After hydrostatic correction of each pressure signal the normalized arterial and venous intra-access pressure ratio AP/MAP can be calculated. A venous stenosis leads to an increase in both arterial and venous pressure ratio. In case of access stenosis between arterial and venous needle the ratio of venous pressure to mean arterial pressure is normal, and only the arterial pressure ratio is elevated. In summary, a combination of arterial and venous pressure measurement is more sensitive and allows differentiation between mid-access and venous stenosis. Hydrostatic correction of the dialysis pressure signal is inevitable. To minimize the rate of access thrombosis, venous and arterial intra-access pressure should be considered when evaluating dialysis pressures as part of any access monitoring program.
Restricted accessResearch articleFirst published April, 2002pp. 64-73In the last ten years, tunneled central venous catheters (pCVCs) have been increasingly utilized in chronic hemodialysis patients, sometimes in the place of fistulas. They have gained popularity for their unquestioned advantages, such as the possibility for immediate use. However, several problems have emerged following their diffusion. In this paper we review the main complications of pCVCs. Complications connected with insertion are generally due to an inaccurate approach to the vein. Ultrasonographic guidance has partially solved this problem and EC-ECG (endocavitary ECG) allows an accurate positioning of the tip. Infections, venous and/or pCVCs) thrombosis and dysfunctions are the most important catheter-related complications. Infections may occur with and without symptoms of systemic illness. Early diagnosis and appropriate antibiotic treatment are essential for saving the catheter. The pathogenesis of infections and strategies for prevention are discussed. Thrombosis and stenosis are well known complications of subclavian and jugular catheterization. In uremic patients, for temporary use, we suggest using the femoral position. Protocols for application of thrombolytic agents in pCVCs are considered. Dysfunction, defined as the failure to maintain a blood flow of at least 250 ml/min, remains the Achilles’ heel of the system. Adequate look therapy and tip position are only two basic aspects. In conclusion, a pessimistic outlook on the matter could lead us to consider that the advantages of catheter use are far outweighed by the disadvantages. However, we cannot avoid using central venous catheters in our dialysis units and a great challenge awaits both physicians and manufactures in the coming years.
Restricted accessResearch articleFirst published April, 2002pp. 74-79Populations of elderly and type-II diabetics are increasing worldwide. Therefore elderly diabetics on hemodialysis (HD), known to have higher nasal carriage rates, are also increasing. These patients are more often dialyzed through central venous catheters (CVCs). They represent the high-risk groups for Staphylococcus aureus linked vascular access-related septicemia (VRS) and ensuing mortality. The outcome of VRS in terms of mortality was studied in the three high-risk groups: elderly; type-II diabetics; elderly diabetics, following optimization of arteriovenous fistula (AVF) prevalence to at least 50%.
Persistent nasal carriage was defined by two or more positive standardized nasal swab cultures performed on 187 ESRD patients undergoing HD from July 1997 to July 2000. Peripheral blood samples were collected for culture and sensitivity on clinical suspicion of septicemia. Overall, AVF prevalence of over 50% was achieved through joint efforts of nephrology and vascular surgery departments.
A nasal carriage rate of 47.6% was observed in this HD cohort. This included nasal carriage rates of 16.4% in <65 years non-diabetic (reference) group, 55.8% in elderly and 70.7% among type-II diabetics along with that of 75.5% in elderly-diabetic group. We achieved an overall AVF prevalence of 72.7% inclusive of 66.17% in elderly, 65.5% in type-II diabetics and 86.8% in reference group along with 37.7% in elderly-diabetic group. We recorded a mortality due to S. aureus nasal carriage-related VRS of 6.86% in elderly (RR-1.50, p-NS), 10.91% in type-II diabetics (RR-1.52, p<0.02) and 13.20% in the elderly-diabetic group (RR-2.87, p<0.0004) as compared to that of 4.4% per year in the reference group (assigned RR of one) with overall mortality of 7.3% per year.
AVF prevalence of over 50% is achievable in all the high-risk groups except among elderly-diabetics due to the predominance of peripheral vasculopathy. Optimizing AVF placement is a physiological and safer approach for achieving significant reductions in mortality associated with S. aureus nasal carriage-related VRS among high-risk groups.
Restricted accessResearch articleFirst published April, 2002pp. 80-84A retrospective study was designed to evaluate the outcome of native wrist arteriovenous fistula (AVF) constructed with standard versus venous “patch” techniques in terms of immediate, early and late failures. Between January 1991 and July 2001, 1948 patients underwent primary wrist radiocephalic AVF. Thirty eight per cent (740) of the fistulas were created using the venous patch technique. Immediate and/or early failure rate was significantly lower in the venous “patch” technique (Group II) compared to the standard technique (Group I). Although the difference in late failures between Groups I and II did not reach statistical significance, the cumulative patency rates were significantly better in Group II. Radiocephalic fistula constructed with the use of venous patch is recommended whenever the anatomy is feasible.
Restricted accessResearch articleFirst published April, 2002pp. 85-88One of the complications of arteriovenous fistulas in chronic hemodialyzed patients is the onset of an aneurysm which can be at risk of rupture.
Traditional surgical repair is not always feasible and may not be successful in these cases, leading therefore to the loss of a functioning vascular access and requiring in any case the temporary use of a central venous catheter to allow regular hemodialysis sessions.
We applied to this kind of aneurysm the same experience developed in the management of major arterial aneurysms and we considered endografting repair a good alternative in this case. In this paper we present the successful treatment of an arteriovenous fistula aneurysm using that technique.
A distal radio-cephalic arteriovenous fistula in one of our patients presented an aneurysm with high risk of rupture. The endografting repair with percutaneous insertion of a Wallgraft™ endoprosthesis was well tolerated and the vascular access could be used the day after, without the need for a central venous catheter insertion.
Restricted accessAnnouncementFirst published April, 2002pp. 89-89