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A Bakran

Publications and source records attributed to A Bakran.

At least 37 records · Page 2Linked to original sources
PubMed1998

Characterizing flow distributions in AV fistulae for haemodialysis access.

BACKGROUND: The arteriovenous fistula is the most widely used means of enabling vascular access for chronic haemodialysis. When interest in vascular access was at its height, in the 1970s, a substantial amount of work was carried out on the physiology of arteriovenous fistulae and on the relationship between fistula flow and patency. One omission in the catalogue of studies was research into the distribution of flow in the fistula and the effects on surgical outcome. METHOD: To address this issue, 30 patients with end-to-side radiocephalic fistulae were studied. Flow measurements were made intraoperatively, and at various intervals postoperatively using colour-flow ultrasonography. RESULTS: In 22 cases, the development of the fistula was monitored at regular intervals for periods of up to 27 months. In seven of the 30 fistulae, flow in the distal artery was antegrade, while in the remaining 23, distal artery flow was retrograde. The proportion of fistula flow supplied by the proximal and distal arteries varied considerably. CONCLUSION: Despite the wide range of flow distributions in the fistulae studied, flow distribution did not appear to affect fistula maturation or long-term function.

Adult↗
PubMed1998

Use of laboratory assays to predict cytomegalovirus disease in renal transplant recipients.

Eight laboratory assays, viz., the pp65 direct antigenemia test, a quantitative cytomegalovirus (CMV)-specific immunoglobulin G (IgG) assay (Biomerieux VIDAS), a CMV-specific IgM assay (Biomerieux VIDAS), the Hybrid Capture system (Murex), an in-house PCR with plasma (P-PCR) and leukocytes (L-PCR), and a commercial PCR (Roche AMPLICOR) with plasma (P-AMP) and leukocytes (L-AMP), were compared for their abilities to predict CMV disease before the onset of illness in a prospective study of 37 renal transplant recipients. By using an expanded criterion for active infection (two or more of the markers positive) and a clinical definition of disease, 22 (59%) patients were identified as having active CMV infection and 13 (35%) were identified as having CMV disease. Of the 13 CMV-seronegative recipients who received seropositive kidneys (R- group), 8 had active infection and disease. All assays were 100% specific and 100% predictive of CMV disease in the R- group. The leukocyte PCRs (L-PCR and L-AMP) were the most sensitive assays, had positive results an average of between 8 and 13 days before the onset of illness, and were the assays of choice. The performance of the assays was less satisfactory for the 24 patients who were CMV seropositive before transplantation (R+ group). A negative result was more useful for this group. Overall, P-AMP had the best results, and it could be the assay of choice for monitoring R+ patients. The non-PCR-based methods generally had high specificities but often gave late positive results and were not sensitive enough for use as prediction tools for either group of patients.

Antibodies, Viral↗
PubMed1996

Factors associated with early failure of arteriovenous fistulae for haemodialysis access.

The radiocephalic arteriovenous fistula remains the method of choice for haemodialysis access. In order to assess their suitability for fistula formation, the radial arteries and cephalic veins were examined preoperatively by ultrasound colour flow scanner in conjunction with a pulse-generated run-off system. Intraoperative blood flow was measured after construction of the fistulae. Post-operative follow-up was performed at various intervals to monitor the development of the fistulae. Radial artery and cephalic vein diameter less than 1.6 mm was associated with early fistula failure. The intraoperative fistula blood flow did not correlate with the outcome of the operation probably due to vessel spasm from manipulation. However, blood flow velocities measured non-invasively 1 day after the operation were significantly lower in fistulae that failed early compared with those that were adequate for haemodialysis. Most of the increase in fistula diameter and blood flow occur within the first 2 weeks of surgery.

Arm↗
PubMed1995

Core needle biopsy in renal transplantation.

Core biopsies have been done by ultrasound assisted 18-G disposable needles with a spring loaded gun (Biopty) system in 140 renal transplant cases either for investigation of an early non-functioning graft or evaluation of deteriorating graft functions. The biopsy procedure was successfully completed in 99.5% and sufficient amount of renal tissue was obtained in 88% of cases. The pathological diagnoses were confirmed 100% by the other clinical parameters of cases with acute cellular rejection, pyelonephritis, acute tubular necrosis and there was disease recurrence. In another 8 patients (6%) where the pathological picture was showing either no or nonspecific changes there was no major change in clinical outcome. In addition, clinical diagnoses of chronic vascular rejection and Cyclosporin A toxicity were confirmed in 93.7% and 91.7%, respectively, in biopsies of these cases. Complications were seen in 3 patients as a bowel perforation, intra-abdominal bleeding and formation of an intrarenal arterio-venous fistula. In former two complicated cases there was no need for any extra treatment but the arterio-venous fistula was successfully embolized through an angiography catheter without losing the graft. We conclude that the Biopty system is more efficient than the fine needle aspiration biopsy especially when the pathological diagnosis can be made upon tissue components rather than cells alone.

Biopsy, Needle↗
PubMed1994

Input impedance of radiocephalic arteriovenous fistulae for haemodialysis access: its value in predicting early failure.

This study is concerned with an assessment of the quality of the blood vessels used in the construction of radiocephalic arteriovenous fistulae for haemodialysis vascular access in 20 patients. Following non-invasive preoperative assessment of the cephalic vein by means of a colour Doppler scanner, input impedance was determined intraoperatively from blood flow and blood pressure measured about 2 cm downstream of the anastomosis. The patients were re-assessed 1 day and 2, 4, 6 and 12 weeks after surgery, and the diameter and the flow through the fistulae, the location of major branches, and the presence and severity of stenoses in the cephalic veins were determined non-invasively. Five fistulae failed within the 12 weeks period following surgery, mainly due to thrombosis. In a further 3 patients, the fistulae were patent but did not achieve an adequately high blood flow and dilate sufficiently for haemodialysis and were therefore considered to be essentially failed. The impedance moduli from 0 to 10 Hz as well as the average impedance modulus of successful fistulae were significantly lower than those of fistulae that subsequently failed. An attempt was made to locate the presence of reflection sites (i.e. stenoses and branches) from the minima in the impedance modulus spectra. Their locations were compared with those of the reflection sites detected by ultrasound 2 weeks after surgery. However, not all reflection sites detected 2 weeks after surgery were located by the impedance method. It is recommended that both preoperative examination and intraoperative haemodynamic measurements be made to improve the accuracy of the assessment.

Arteriovenous Shunt, Surgical↗
PubMed1993

Upper limb venous gangrene, a lethal condition.

Venous gangrene of the upper extremity is rare. It was the mode of presentation in a 41-year-old woman who died 10 days later of heart failure due to acute myocardial infarction. There is evidence from this and previous publications that patients with this condition tend to have characteristics in common. Most have either advanced malignant disease or seriously impaired myocardial function and venous gangrene usually occurs as a pre-terminal event. Treatment should be directed primarily at the underlying illness but there may be a case for early amputation if permitted by the general condition of the patient.

Adult↗
PubMed1993

ePTFE grafts for femoro-crural bypass--improved results with combined adjuvant venous cuff and arteriovenous fistula?

Patency rates for long prosthetic bypass grafts with standard anastomoses to single tibial or peroneal arteries are very poor. Adjuvant techniques employed with the aim of improving patency rates include arteriovenous fistula (AVF) at the distal anastomosis to accelerate blood flow above thrombotic threshold velocity (TTV) and a venous cuff (VC) or patch which may reduce or modify anastomotic myointimal hyperplasia within the recipient artery. In a consecutive series of 43 femoro-crural bypasses with ePTFE grafts, adjuvant AVF and VC procedures have been applied in combination. The results are compared with those of an antecedent series of 76 similar grafts with AVF alone and a contemporaneous series of 179 autologous vein grafts. All operations were undertaken for critical limb ischaemia with anastomosis to a single calf or pedal artery. The three groups were well matched for age, sex, diabetes, smoking history, previous surgery and the proportion with rest pain and tissue necrosis. The cumulative patency rate at 2 years for ePTFE grafts with combined AVF and VC was 62% compared to 28% for those with AVF alone and 68% for autologous vein grafts. The patency rate for prosthetic grafts with AVF and VC was significantly higher than AVF alone (p < 0.01) and did not differ significantly from vein grafts. Cumulative limb salvage rates for ePTFE grafts with AVF and VC were 68% at 1 year and 55% at 2 years compared to 38 and 35% for AVF alone and 78 and 69% for vein grafts.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Intra-arterial injection of temazepam in drug abusers.

The effects of intra-arterial injection of Temazepam are described in 11 drug abusers admitted over a 6 month period. All patients suffered severe ischaemia, and injection into the radial artery invariably resulted in tissue loss leading to amputation. The pathogenesis and options for treatment are discussed.

Adult↗
PubMed1993

Uromodulin levels are decreased in urine during acute tubular necrosis but not during immune rejection after renal transplantation.

1. Uromodulin, an immunosuppressive glycoprotein found in urine, is a high-affinity binding ligand for certain cytokines, including tumour necrosis factor. 2. Its occurrence in urine was monitored after renal transplantation to investigate whether this simple urine test might differentiate common early causes of graft failure: acute immune rejection and acute tubular necrosis. 3. Diluted urine was assayed for uromodulin using a sandwich enzyme-linked immunosorbent assay. When graft function failed due to acute tubular necrosis, urinary uromodulin levels were significantly depressed compared with levels in urine produced during biopsy-proven acute immune rejection episodes (P < 0.01) or during periods of stable graft function (P < 0.02). This suggests that urinary levels of uromodulin may reflect tubular damage rather than other causes of graft functional failure. 4. The cytokine tumour necrosis factor, which binds with high affinity to uromodulin, was found in 30% of urine samples in association with immune rejection episodes, but not during acute tubular necrosis. However, the presence of urinary tumour necrosis factor was not related to levels of uromodulin in the same sample.

Enzyme-Linked Immunosorbent Assay↗