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Biomedical subjects

G M Preminger

Publications and source records attributed to G M Preminger.

At least 91 records · Page 5Linked to original sources
PubMed1995

Comparison of open and endourologic approaches to the obstructed ureteropelvic junction.

OBJECTIVES: To compare open pyeloplasty with three minimally invasive modalities: antegrade endopyelotomy, Acucise endopyelotomy (Applied Medical, Laguna Hills, Calif), and laparoscopic pyeloplasty. METHODS: Forty-five adult patients with ureteropelvic junction obstruction were managed by one of the above four techniques. Success rates, analgesic use, length of hospital stay, recovery time, and complications were compared between each of the four groups. RESULTS: Successful relief of obstruction was achieved in 100% of patients undergoing open and laparoscopic dismembered pyeloplasty, 78% undergoing Acucise endopyelotomy, and 77% undergoing antegrade percutaneous endopyelotomy. Acucise endopyelotomy results in shorter convalescence (1 week) than antegrade endopyelotomy (4.7 weeks), laparoscopic pyeloplasty (2.3 weeks) or open pyeloplasty (10.3 weeks). Complication rates appear to be similar among all groups. CONCLUSIONS: Our limited data imply that Acucise endopyelotomy offers low morbidity with success rates comparable to antegrade pyeloplasty, whereas laparoscopic pyeloplasty is as effective as open pyeloplasty with diminished morbidity.

Adult↗
PubMed1995

Effect of medical management and residual fragments on recurrent stone formation following shock wave lithotripsy.

Minimal emphasis has been placed on the clinical sequelae of residual stone fragments following shock wave lithotripsy. Moreover, there are no studies investigating the role of medical therapy on the course of stone disease in patients with residual fragments. In this retrospective, nonrandomized review, we evaluated 80 patients who had undergone shock wave lithotripsy at various institutions in Texas and were referred to our mineral metabolism clinic for metabolic evaluation and medical management of the stone disease. Of the patients 31 were determined to be stone-free following lithotripsy, while 49 had residual stone fragments. All patients were contacted an average of 43.2 months (range 9 to 79) following shock wave lithotripsy and the radiographs were reviewed. Patients were placed into 4 groups after shock wave lithotripsy: stone-free or residual fragments on or off medical therapy. In the stone-free group (19 patients), medical treatment produced a significant decrease in stone formation from a median of 0.67 to 0.0 stones per patient per year (p < 0.001). In 36 patients with residual fragments stone formation before shock wave lithotripsy was higher than in the stone-free group but there was also a significant decrease in the stone formation rate from a median of 2.47 to 0.00 stones per patient per year while on medical therapy (p < 0.001). Of the 12 stone-free patients who did not remain on medical therapy there was a slight decrease in the stone formation rate from a mean of 0.83 to 0.40 stones per patient per year, although this decrease was not significant (p = 0.07). In 13 patients with residual fragments not on medical treatment there was only a minimal decrease in the stone formation rate from a median of 1.33 to 0.77 stones per patient per year (p = 0.06). We also assessed the significance of so-called clinically insignificant residual fragments (smaller than 5 mm.) following shock wave lithotripsy in 26 of the 36 patients with residual fragments. More than half of the 26 patients with clinically insignificant fragments in the group that did not continue on medical therapy demonstrated significant stone growth during followup, suggesting that these fragments were not insignificant. Moreover, only 16% of the patients with fragments smaller than 5 mm. demonstrated an increase in fragment size while on medical therapy, again suggesting that appropriate medical treatment can decrease the risk of recurrent stone formation or growth (p < 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1995

Lower pole calicostomy for the management of iatrogenic ureteropelvic junction obstruction.

It is often possible to use endoscopic techniques for the management of iatrogenic upper ureteral or ureteropelvic junction obstruction. However, in some cases with severe stricture disease or significant ischemic injury open surgical reconstruction is necessary. We report our experience with ileal ureter-lower pole calicostomy for the management of these complex urological injuries. During the last 3 years we treated 3 patients with severe ureteral/ureteropelvic junction obstruction secondary to iatrogenic injuries, including ureteral avulsion during ureteroscopic stone extraction, ureteral laceration during dilation for diagnostic ureteropyeloscopy, and ureteral ligation with ureteropelvic junction disruption and large peri-pelvic urinoma. In all cases unsuccessful attempts at endoscopic management necessitated open repair. Lower pole heminephrectomy was performed in all patients to expose the lower pole calix and ileal ureter-lower pole calicostomy was created due to the injury of large segments of the ureter. Satisfactory results were demonstrated on postoperative excretory urography and by a lack of symptoms. Followup averaged 23 months (range 20 to 26) with stable renal function in all patients. We believe that ileal ureter-lower pole calicostomy represents an attractive alternative for the management of severe ischemic, iatrogenic upper ureteral or ureteropelvic junction obstruction when endoscopic maneuvers are not possible or ineffective.

Adult↗
PubMed1994

Nephrolithiasis Clinical Guidelines Panel summary report on the management of staghorn calculi. The American Urological Association Nephrolithiasis Clinical Guidelines Panel.

The American Urological Association Nephrolithiasis Clinical Guidelines Panel recommendations for managing struvite staghorn calculi are based on a comprehensive review of the treatment literature and meta-analysis of outcome data from the 110 pertinent articles containing viable, unduplicated data. The panel concluded that the 3 most significant outcome probabilities are those of being stone-free, undergoing secondary unplanned procedures and having associated complications. Panel guideline recommendations for most standard patients are that neither shock wave lithotripsy monotherapy nor open surgery should be a first-line treatment choice but that a combination of percutaneous stone removal and shock wave lithotripsy should be used.

Humans↗
PubMed1994

Laparoscopic removal of gonads containing on occult seminoma in a woman with complete androgen resistance.

A 20-year-old woman with complete androgen resistance (AR; 46,XY), underwent prophylactic laparoscopic gonadectomy because of the known increased risk of gonadal malignancy. The procedure was performed with electrocoagulation using a four-puncture technique. Pelvic and abdominal inspection revealed no gonadal or metastatic tumor. The testes and attached structures were retracted medially, and the peritoneum and gonadal vessels were incised after electrocoagulation, thereby removing the gonads from the sidewalls. The gonads were individually placed into a specimen retrieval bag and removed through the suprapubic cannula site. Pathologic examination revealed an occult 8-mm seminoma in the let gonad, as well as bilateral Sertoli cell hamartomas, fallopian tube remnants, and smooth muscle tissue (mullerian remnants) adjacent to the gonads. Postoperatively, tumor markers were normal, and abdominal and pelvic computerized tomographic scans and chest radiographs were negative for possible metastatic disease. This case confirms that laparoscopic removal of testes in women with AR is effective, safe, and quick. Because of normal-appearing gonad may contain an occult tumor, we recommend using a retrieval bag, which may prevent dissemination of potentially malignant cells that may occur with unprotected morcellation.

Adult↗
PubMed1994

Mechanisms of differing stone fragility in extracorporeal shockwave lithotripsy.

Clinical experience with extracorporeal shockwave lithotripsy (SWL) has demonstrated significant variations in stone fragility. To understand the physical mechanisms of the differences, we quantitatively determined shockwave-stone interaction under clinically relevant SWL conditions for six stone compositions: calcium oxalate monohydrate (COM), struvite (MAPH), calcium apatite (CA), uric acid (UA), brushite, and cystine. We also characterized the acoustic and mechanical properties of the stones using ultrasound and microindentation techniques. Our results show that renal calculi have distinctly different acoustic and mechanical properties. Higher wave speed, Young's modulus, and fracture toughness were measured from COM and cystine stones, whereas lower values of the corresponding properties were found in CA and MAPH, and the values for brushite and UA stones were in between. Computer modeling of shockwave propagation revealed that under the same shockwave intensity, larger deformation was induced in CA and MAPH stones than in COM and cystine stones. In addition, multiple reflected tensile waves were predicted for stones with concentric layer structure, indicating their susceptibility to shockwave fragmentation. These findings elucidate the mechanisms of the differences in stone fragility observed clinically. Their implications to SWL are discussed.

Humans↗
PubMed1994

Retroperitoneal laparoscopic nephrectomy and other procedures in the upper retroperitoneum using a balloon dissection technique.

This article describes a hydraulic balloon dissection technique. The retroperitoneum is developed via a small lumbodorsal incision between the edges of the musculus latissimus dorsi and musculus obliquus externus and then after visualization of its correct position the balloon catheter is filled with 500-1,200 ml of warm normal saline (according to patient size). The device consists of the finger of a surgeon's glove ligated around the end of a rigid bladder catheter. The balloon insufflation is maintained for 5 min to guarantee adequate hemostasis. Recently, we have replaced the balloon catheter by a balloon trocar sheath allowing direct endoscopic control of the hydraulic dissection. After retrieval of the balloon the CO2 insufflator is connected to the first trocar. All secondary trocars are placed under endoscopic control. The hydraulic dissection techniques also enable optimal creation of an effective pneumoperitoneum in children. Until now, we have used this technique for twelve procedures in the upper retroperitoneum including five nephrectomies, two nephroureterectomies, one tumor nephrectomy, one nephropexy, one renal cyst marsupialization and two renal biopsies. Up to now we have encountered no major complications. Three of the nephrectomized patients had undergone multiple previous abdominal surgical interventions. The retroperitoneal approach allows the surgeon to apply similar dissecting techniques as used in respective open procedures. It has become the routine approach for laparoscopic procedures in benign renal disease. This procedure can be performed even in cases with previous abdominal surgery.

Adult↗
PubMed1993

A comparison of the bioeffects of four different modes of stone therapy on renal function and morphology.

A variety of therapeutic options exists for removal of symptomatic renal calculi, including extracorporeal shock wave lithotripsy, percutaneous nephrostolithotomy and open pyelolithotomy or nephrolithotomy. Although lithotripsy offers the advantage of reduced patient morbidity, the relative alterations in renal function and morphology for each of the respective treatment modalities have not been completely assessed. We evaluated 17 pigs (40 to 50 lb.) for evidence of histologic and functional renal changes after a pyelotomy (N = 3) or nephrotomy (N = 4), piezoelectric lithotripsy (N = 5), or placement of a percutaneous nephrostomy tube with balloon dilation (N = 5). Pathologic evaluation one month after treatment revealed no renal scarring in the animals that underwent a pyelotomy and minimal parenchymal fibrosis in the nephrotomy and lithotripsy groups (0.014 +/- 0.001% and 0.015 +/- 0.002%, respectively). In contrast, the percutaneous nephrostomy group demonstrated 1.53 +/- 0.4% of the treated kidney to be involved by scarring (p < 0.001). Despite the statistically significant increase in renal scarring after percutaneous nephrostomy, neither creatinine and PAH clearances nor renal plasma flows changed significantly among the four treatment groups. Moreover, no change in renal function after treatment was observed when compared with baseline evaluations. All four therapeutic options for renal stone removal appear to result in small amounts of renal parenchymal damage but are not associated with significant alterations in renal function.

Animals↗
PubMed1993

Laparoscopic dismembered pyeloplasty.

As laparoscopic nephrectomy has become a viable ablative procedure for kidney removal, additional areas of reconstructive laparoscopic urological procedures are being investigated. We describe our early experience with laparoscopic pyeloplasty for the management of ureteropelvic junction obstruction. Technical highlights include initial placement of an internal ureteral stent, lateral insufflation, placement of 5, 10 mm. trocars, pyelotomy (or reduction pyeloplasty performed with articulating laparoscopic scissors, reapproximation of the ureteropelvic junction with a running 4-zero polyglactin suture, placement of a 7 mm. suction drain in the retroperitoneal space and reapproximation of the colon to the body wall with a hernia stapler. We have performed laparoscopic dismembered pyeloplasty in 5 patients with symptomatic ureteropelvic junction obstruction. Operating time ranged from 3 to 7 hours, with the majority of time devoted to laparoscopic suturing (1 to 3 hours). Hospital stay averaged 3 days and all patients returned to normal activity within 1 week. Followup averaged 12 months (range 9 to 17 months) with complete resolution of symptoms in all patients. We believe that this innovative reconstructive laparoscopic procedure can be used for treatment of complicated ureteropelvic junction obstruction as in patients with a large, redundant renal pelvis or crossing lower pole vessels.

Adult↗
PubMed1993

Treatment philosophy and retreatment rates following piezoelectric lithotripsy.

Second generation lithotriptors offer the advantage of anesthesia-free fragmentation of renal and ureteral calculi but they frequently require multiple treatments to attain a stone-free status. However, excessive single lithotripsy sessions or multiple treatments may be associated with significant damage to the kidney. For some clinicians a common treatment philosophy involves evaluation of serial plain abdominal films every 24 hours after lithotripsy and immediate retreatment of all patients with incomplete fragmentation. To avoid unnecessary retreatments and, thus, minimize potential renal damage, we prospectively evaluated 100 patients undergoing lithotripsy on a Wolf Piezolith 2300 device. Patients were routinely treated with 4,000 shocks at 1,100 bar. Serial plain abdominal films were obtained at 1 day and 2 weeks after lithotripsy. The need for retreatment was determined by the plain abdominal film results. Additional therapy was considered necessary if there was no stone fragmentation or if residual fragments measured greater than 4 mm. Of the patients whose plain abdominal film at 24 hours indicated the need for a repeat treatment 43% were stone-free on the 2-week film. Thus, these patients were spared an unnecessary treatment by allowing adequate time for the stone fragments to pass spontaneously. Our data suggest that repeat treatments on second generation lithotriptors should not be performed within 24 hours. Rather, the patient should be reevaluated at least 1 to 2 weeks later to avoid unnecessary retreatment with the attendant potential for renal injury. In addition, when comparing the retreatment rates of various lithotriptors, one should also consider the treatment philosophy used at the particular institution and the timing of the radiographic studies used to determine the stone-free status.

Electricity↗
PubMed1993

Acoustic and mechanical properties of renal calculi: implications in shock wave lithotripsy.

The acoustic and mechanical properties of renal calculi dictate how a stone interacts with the mechanical forces produced by shock wave lithotripsy; thus, these properties are directly related to the success of the treatment. Using an ultrasound pulse transmission technique, we measured both longitudinal and transverse (or shear) wave propagation speeds in nine groups of renal calculi with different chemical compositions. We also measured stone density using a pycnometer based on Archimedes' principle. From these measurements, we calculated wave impedance and dynamic mechanical properties of the renal stones. Calcium oxalate monohydrate and cystine stones had higher longitudinal and transverse wave speeds, wave impedances, and dynamic moduli (bulk modulus, Young's modulus, and shear modulus), suggesting that these stones are more difficult to fragment. Phosphate stones (carbonate apatite and magnesium ammonium phosphate hydrogen) were found to have lower values of these properties, suggesting they are more amenable to shock wave fragmentation. These data provide a physical explanation for the significant differences in stone fragility observed clinically.

Humans↗
PubMed1993

Transperitoneal laparoscopic nephrectomy: training, technique, and results.

Transperitoneal laparoscopic nephrectomy was integrated into our daily routine within a 6-month period by means of a step-by-step training program progressing from a pelvic trainer to animal studies (N = 15) to laptent-assisted surgery. The pneumoperitoneum is created with the patient in the flank position, enabling insertion of three trocars: 10-mm periumbilical (Port I), 5/12-mm subcostal (Port II), and 12/5-mm above the iliac spine (Port III). After medial mobilization of the colon, two additional 5-mm trocars (Ports IV and V) are inserted into the lateral abdominal wall parallel to Ports II and III. Once clipping and dissection of the ovarian (spermatic) vein has been carried out, the ureter is identified and dissected. Retraction of the proximal ureter exposes the renal hilum, allowing dissection of the renal vessels. The renal vein is dissected using an endoscopic stapling device, while accessory veins and the renal artery are clipped. Organ retrieval is achieved with a specially designed tissue pouch (Lapsac) and digital fragmentation of the kidney within the organ bag. Using this technique, we have treated 24 patients with benign (N = 20) and malignant (N = 4, including adrenalectomy) renal disease. The mean operative time was 239 (115-300) minutes. In four cases, open surgery was required because of bleeding (N = 2), severe perinephric inflammation (N = 1), or bowel injury (N = 1). For relief of wound pain, an average of 1.15 vials of analgesic (morphine derivatives)/patient were administered for 2.4 days. The postoperative hospital stay averaged 6.2 (4-10) days.

Animals↗