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Biomedical subjects

E S Lyon

Publications and source records attributed to E S Lyon.

At least 19 recordsLinked to original sources
PubMed1995

Applicability of Iceland spar as a stone model standard for lithotripsy devices.

The identification of a universal stone model standard would enable reproducible fragmentation data useful for the design, evaluation, and comparison of various lithotripsy devices. The clinical benefits of such a stone model include the elucidation of setting parameters that would optimize fragmentation strategies. Iceland spar is a pure form of calcite (CaCO3) that was subjected to experimental disintegration by electrohydraulic lithotripsy and extracorporeal shockwave lithotripsy. Iceland spar was fragmented with both lithotripsy methods in a reproducible fashion. The degree of fragmentation was directly related to alterations in either power or shock frequency. Iceland spar is radiopaque, inexpensive, easily obtained, homogenous in composition, and sizable. Iceland spar meets a variety of stone model criteria, warranting its continued investigation as a potential stone model standard.

Calcium Carbonate↗
PubMed1994

Endopyelotomy: patient selection, results, and complications.

The popularity of minimally invasive surgical techniques, such as endopyelotomy, has increased markedly among urologists in recent years. While it was initially thought that this procedure was best utilized in patients with secondary UPJ obstruction, recent evidence suggests that endopyelotomy should be considered in the majority of cases. The primary contraindication to endoscopic incision of the UPJ is a long stricture, although a large redundant renal pelvis and the presence of crossing lower pole vessels are considered by some to be relative contraindications as well. Although the majority of surgeons have used a percutaneous, antegrade approach to endopyelotomy, successful results also have been reported with a ureteroscopic, retrograde technique. With the development of modified ureterotomes and balloon-cutting devices, the retrograde approach eventually may become the preferred method since no skin incision or external drainage are needed. The role of endopyelotomy in children remains undefined. While successful results have been reported in infants, the relative morbidity and long-term success of open pyeloplasty in this age group are excellent, thus limiting the relative advantage of an endoscopic approach. However, there may be a role for endopyelotomy in older children and in those patients with secondary obstruction who have failed open surgery. From a technical standpoint, there are several minor variations in surgical technique and postoperative management that are important. The success rate of endopyelotomy using a cold knife or small electrocautery probe appears to be comparable, and the use of cautery may allow for precise control of minor bleeding thus decreasing the risk of complications. However, larger electrodes may induce greater tissue reaction leading to fibrosis and should be avoided. Postoperatively, most authors prefer a tapered double-pigtail stent which allows for adequate internal drainage while avoiding excessive pressure within the distal ureter. While successful results have been reported with stenting intervals of only four days, it is generally recommended that the stent be left in place for a minimum of six weeks following endoscopic incision of the UPJ. Overall, endopyelotomy is associated with shortened hospitalization, more rapid return to normal activity levels, and decreased morbidity compared with open pyeloplasty. The success rates reported with endopyelotomy approach those achieved with open surgery, and it is likely that an endoscopic approach to UPJ obstruction will assume an increasingly greater role in the future.

Adolescent↗
PubMed1993

Management of acute ureteral obstruction in pregnancy utilizing ultrasound-guided placement of ureteral stents.

Of 6,275 pregnancies seen at our institution over a two-year period, 5 patients required operative intervention for acute urinary obstruction unresponsive to medical management. Ultrasonography was able to definitively diagnose the presence of an obstructing calculus in 4 of 5 patients. Using ultrasound guidance, 7 indwelling ureteral stents were successfully placed with local anesthesia supplemented by intravenous sedation. Complications consisted of distal stent migration in 1 patient. This method of management was successful for symptomatic nephrolithiasis in a pregnant renal transplant patient. Endoscopic placement of ureteral stents under ultrasound guidance is an effective, safe method of urinary decompression, with no radiation risks imparted to the mother or fetus. Definitive therapy then can be safely deferred to the post-partum period.

Acute Disease↗
PubMed1993

Endourological management of upper tract urothelial tumors.

Advances in ureteroscopic and percutaneous techniques have made it possible to treat many upper tract malignancies by conservative, parenchyma sparing surgery. Percutaneous techniques generally allow for easier and better access to the renal pelvis and improved tumor resection. However, concerns for tumor spillage and nephrostomy tract seeding make the ureteroscopic approach best for initial management of accessible renal pelvic lesions, particularly when the diagnosis is unclear. Ureteral tumors, especially those arising in the lower third of the ureter, are technically easier to treat endoscopically than are renal pelvic tumors. Fulguration or laser photocoagulation may be used to ablate the tumor following cold-cup biopsy for histological diagnosis. Supplemental therapy using laser treatment of the tumor base, and postoperative instillation of BCG and mitomycin C offer great potential benefit in terms of improved tumor control. Confirmation of such benefit awaits the results of larger trials. Presently, standard nephroureterectomy remains the procedure of choice for most transitional cell carcinomas of the upper urinary tract in patients with a normal contralateral kidney. For those with a solitary kidney, renal insufficiency, bilateral tumors or severe intercurrent disease preventing a major open operation conservative management using endoscopic techniques is a viable alternative. Overall, it appears that grade and stage are far more important determinants of long-term out-come than the type of operation in those with transitional cell carcinoma of the upper urinary tract. For this reason, some physicians have recommended conservative management of low grade, noninvasive lesions even in the face of a normal opposite kidney. However, the majority of patients with upper tract urothelial tumors are best treated by nephroureterectomy, which leads to a low risk of local recurrence and obviates the need for rigorous postoperative upper tract surveillance.

Carcinoma, Transitional Cell↗
PubMed1989

Treatment options for proximal ureteral urolithiasis: review and recommendations.

The treatment of proximal ureteral calculi has been altered markedly by recent developments in shock wave lithotripsy (bypass, pushback and in situ), ureterorenoscopy and percutaneous stone removal. In an effort to discern the proper role of these newer treatment options with respect to ureterolithotomy (flank approach or dorsal lumbotomy), we completed a multicentered study in which 142 upper ureteral stone patients in 7 different treatment categories were reviewed retrospectively and contacted for convalescence data. From these data we conclude that before extracorporeal shock wave lithotripsy an upper ureteral stone should be manipulated until it is either pushed back to the kidney or bypassed with a stent. This maneuver should result in successful extracorporeal shock wave lithotripsy in more than 90 per cent of the patients. For those few patients with an impacted upper ureteral calculus ureterorenoscopy is recommended. Given the presently available treatment modalities we conclude that less than 3 per cent of all upper ureteral calculi will require ureterolithotomy. In this last circumstance a dorsal lumbotomy incision appears to be less morbid and yet as effective as anterior ureterolithotomy.

Algorithms↗
PubMed1988

Lidocaine jelly push-back of ureteral stones.

Pushing ureteral stones into the renal pelvis significantly facilitates extracorporeal shock-wave lithotripsy or percutaneous nephrolithotripsy. The technique is simple and less hazardous than mechanically relocating the stone with a wire or a catheter. It requires retrograde injection of 2% lidocaine jelly into the ureter via an 8-10F catheter placed just distal to the stone. Of forty-seven ureteral stones (24 upper, 19 mid, and 4 lower ureter), 44 were relocated successfully.

Humans↗
PubMed1987

Flexible ureteropyeloscopy: diagnosis and treatment in the upper urinary tract.

Flexible ureteropyeloscopy was performed on 59 patients with 2.7, 3.2 or 3.6 mm. endoscopes with a deflectable tip. Techniques for use of these flexible endoscopes are discussed in detail. The endoscope could be passed into the ureter in 58 patients and into the kidney in 52 (88 per cent). The entire collecting system was visualized in 23 of the most recent 29 patients (79 per cent). A diagnosis was achieved in all 23 patients with an intrarenal filling defect demonstrated radiographically. The source of gross hematuria alone could be defined in 9 of 17 patients. Surveillance for tumor was achieved in 5 of 5 patients and for residual calculus in 4 of 4. The endoscope was used to establish continuity successfully in 3 patients with an obstructed ureteropelvic junction. An instrument with a deflectable tip and some technique for irrigation are essential for intrarenal inspection and complete visualization of the ureter. This procedure is valuable in selected patients and it rapidly may become the technique of choice for the diagnosis of intrarenal filling defects. It also is of value in patients with benign, essential hematuria.

Aged↗
PubMed1985

Endoscopic diagnosis and treatment of upper-tract urothelial tumors. A preliminary report.

The technique of transurethral ureteropyeloscopy allows many standard cystoscopic procedures to be extended into the upper urinary tract. This endoscopic method was used to evaluate 31 patients suspected to have urothelial malignancies of the ureter or renal pelvis. Twenty-eight of the patients had the procedure successfully completed (90%), 11 of whom were found to have urothelial tumors. Diagnostic ureteroscopic biopsy in three of these patients revealed high-grade, multifocal tumors and was followed by nephroureterectomy (two patients) or partial ureterectomy (one patient). However, in eight patients, ureteroscopy and biopsy revealed apparently localized, low-grade tumors which were treated by ureteroscopic fulguration or resection. The latter patients have undergone endoscopic surveillance every 3 months (average follow-up, 21 months). The technique of ureteropyeloscopy permits endoscopic access into the ureter and renal pelvis, enabling tissue diagnosis and better preoperative cancer staging without surgical exploration. Although follow-up is short, selected patients with low-grade tumors may be treated primarily by endoscopic means.

Aged↗
PubMed1984

Selective surface staining of bladder tumors by intravesical methylene blue with enhanced endoscopic identification.

Intravesical instillation of methylene blue resulted in selective surface staining of bladder tumors in vivo without staining the background of normal urothelium. Staining of human bladder tumors in vivo was accomplished by the intravesical instillation of 0.1% methylene blue in 0.9% saline through a foley catheter under 20 cm of hydrostatic pressure up to a maximum volume of 400 ml. After 5 minutes contact time, the methylene blue solution was drained, and the bladder was washed with saline. Thereafter, either endoscopic or open surgery was performed. The transitional cell carcinomas in 45 of 48 patients bound methylene blue to the surfaces of the tumors but not to normal urothelium. Higher grade tumors usually bound the dye more extensively than lower grades. The three patients, whose tumors did not bind methylene blue, had received previous chemotherapy, which might account for their being falsely negative. Carcinoma in situ and dysplasia did stain blue. Areas of hyperplasia and cystitis, however, did not bind methylene blue. In vivo intravesical staining with methylene blue has been a simple and safe procedure which has enhanced the endoscopic localization for biopsy and fulguration/resection of transitional cell carcinomas.

Carcinoma in Situ↗
PubMed1984

Ureteroscopy and ureteropyeloscopy.

Transurethral endoscopic access to the upper urinary tract using rigid optics is evolving into a significant addition to the specialty of urology. The basic endoscopic expertise urologists have perfected for use in the urethra, prostate, and bladder is readily transposed to the ureter and renal pelvis. Indications, precautions, instrumentation, and procedural techniques are detailed.

Cystoscopes↗
PubMed1983

Extending cystoscopic techniques into the ureter and renal pelvis. Experience with ureteroscopy and pyeloscopy.

The availability of extended-length, small-caliber endoscopes allows the use of many cystoscopic techniques in the ureter and renal pelvis. Although the instruments are rigid, they can be passed transurethrally in both male and female patients to allow the urologist to diagnose and treat many lesions of the upper urinary tract. The success of our series demonstrates the utility and safety of the technique, which often eliminates the need for surgical exposure of the lesions.

Adult↗
PubMed1983

Transurethral removal of large ureteral and renal pelvic calculi using ureteroscopic ultrasonic lithotripsy.

Transurethral ultrasonic fragmentation of stones allows successful endoscopic removal of upper urinary calculi that otherwise would be considered too large to extract. We successfully extracted endoscopically 2 large renal pelvic and 5 large ureteral stones using transurethral ureteropyeloscopy and ultrasonic lithotripsy. The stone is visualized first with the ureteropyeloscope, and then engaged in a basket and either fragmented or disintegrated with the ultrasonic transducer. Any remaining small stone fragments can be retrieved with a stone basket or forceps. There has been little morbidity with this procedure and patients can return to normal activity after discharge from the hospital.

Adult↗
PubMed1983

Combined rigid and flexible ureteropyeloscopy.

The development of rigid and flexible ureteropyeloscopes has provided the means for direct visualization of the upper urinary collecting system. Each instrument has its own advantages and disadvantages. The combined use of these instruments extends the range of endoscopy throughout the intrarenal collecting system, permits irrigation and provides a working channel.

Adult↗
PubMed1983

In vivo urothelial surface histology by microscopic chromocystoscopy.

Microscopic chromocystoscopy is a new in vivo procedure that we have developed to aid in the detection and treatment of bladder tumors. Intravesical ionic dye chromocystoscopy was introduced by our group to permit cystoscopic viewing with ordinary light of selectively stained malignant urothelial surfaces by the cationic dye, methylene blue. With the recent availability of the Hamou hysteroscope, a microscopic endoscope, we have combined intravesical ionic dye chromocystoscopy with microscopic cystoscopy to give in vivo urothelial surface histology, with resolution of cytological detail. We herein describe our new method and preliminary results with this procedure, which we have designated in vivo urothelial surface histology by microscopic chromocystoscopy.

Cystitis↗