Time-course for recovery of renal function after unilateral (single-tract) percutaneous access in the pig.

INTRODUCTION: The immediate (1-5 hours) response to percutaneous renal access (PERC) in pigs is vasoconstriction in the treated kidney. The present study determined the longer-term (72 hours) consequences of this surgical procedure. MATERIALS AND METHODS: Adult female pigs were anesthetized, and bilateral glomerular filtration rate (GFR), effective renal plasma flow (ERPF), urine flow rate, and sodium excretion rate were measured before and 1 hour after sham PERC or unilateral, single-tract PERC using a balloon dilator system. Animals were allowed to regain consciousness and were then anesthetized 72 hours later for final measurements of bilateral renal hemodynamic and excretory function together with renal para-aminohippuric acid (PAH) extraction (a measure of tubular organic anion transport efficiency). RESULTS: Bilateral renal hemodynamics were unchanged in the sham-PERC-treated pigs over the 72-hour observation period. In contrast, both GFR and ERPF were reduced by approximately 55% in the PERC-treated kidney within 1 hour of access, and returned to pre-PERC levels within 72 hours. Renal hemodynamics were not significantly altered in the opposite, untreated kidney of the PERC-treated pigs. Renal PAH extraction was decreased in PERC-treated kidneys at 72 hours post-PERC. Both sham-PERC-treated and PERC-treated animals showed similar falls in urine flow rate and sodium excretion rate immediately after treatment and at 72 hours after PERC. CONCLUSIONS: Renal vasoconstriction characterized the acute response of the treated kidney to unilateral PERC, whereas impaired tubular function (reduced PAH extraction) with near-normal GFR and ERPF characterizes the later (72 hours) response to PERC.

In vitro assessment of a novel dual probe ultrasonic intracorporeal lithotriptor.

PURPOSE: The Cyberwand (Cybersonics, Erie, Pennsylvania) is a novel intracorporeal lithotrite that uses coaxial ultrasonic elements operating at 2 frequencies. We compared this device to the LithoClast(R) Ultra, which we previously noted is the most efficient commercially available intracorporeal lithotripsy device. MATERIALS AND METHODS: An in vitro test system was used to assess the efficiency of stone penetration for the Cyberwand and the LithoClast Ultra. The devices were mounted upright with the probe tip up in a modified irrigation sheath. A gypsum artificial stone was centered on the probe tip and a mass was placed atop the stone to provide a constant force. The manufacturer recommended setting was selected for the Cyberwand, while for the LithoClast Ultra a pneumatic frequency of 12 Hz with an ultrasonic power setting of 100% was selected, representing optimal settings in previous in vitro tests. The time required for complete stone penetration was measured. Differences in mean stone penetration times were compared using ANOVA. RESULTS: Mean +/- SD penetration time for the Cyberwand was significantly shorter than for the LithoClast Ultra (4.8 +/- 0.6 vs 8.1 +/- 0.6 seconds, p <0.0001). Neither device showed any difficulties with overheating, occlusion or another malfunction. CONCLUSIONS: Initial assessment using our hands-free in vitro test system, in which stone penetration time is not affected by operator bias, suggests that the Cyberwand is an efficient lithotrite. These promising results justify in vivo testing.

Change in serum prostate specific antigen concentration after holmium laser enucleation of the prostate: a marker for completeness of adenoma resection?

BACKGROUND AND PURPOSE: Holmium laser enucleation of the prostate (HoLEP) is a well-established technique for the treatment of benign prostatic hyperplasia (BPH). To date, changes in serum prostate specific antigen (PSA) after HoLEP have not been published. We hypothesized that HoLEP produces a diminution in PSA similar to that produced by the gold-standard therapies for BPH. To test this hypothesis, we have examined PSA data before and after HoLEP from two institutions performing high volumes of this procedure. PATIENTS AND METHODS: Between August 1998 and September 2004, 509 HoLEPs were performed at two institutions for which complete PSA data were available. Preoperative demographic and transrectal ultrasonography (TRUS) volume measurements were recorded; postoperative pathology and TRUS volume were obtained. Change in PSA as a function of the weight of prostate resected and the relation of preoperative TRUS volume to PSA was determined. RESULTS: The average weight of adenoma resected was 49.8 g (range 5-300 g) in the McGill group and 90.4 g (range 7.9-312 g) in the Methodist Hospital group. The mean decrease in PSA was 81.7% in the McGill group (range 6.0-1.1 ng/mL; P < 0.0001) and 86.0% in the Methodist Hospital group (range 8.6-1.2 ng/mL; P < 0.0001). Log transformed preoperative PSA correlated well with TRUS volume (r = 0.45), as did the weight of adenoma resected with absolute change in PSA (r = 0.38). The TRUS volume decreased significantly, from 111.9 cc to 26.5 cc, in the Methodist Hospital group (P < 0.0001). CONCLUSION: The HoLEP procedure produces a significant diminution in PSA that correlates well with the weight of adenoma resected. Measurement of PSA may be a useful tool for the objective assessment of ablative therapies for BPH, as the reduction in PSA corresponds well with the amount of adenoma removed.

Using and choosing a nephrostomy tube after percutaneous nephrolithotomy for large or complex stone disease: a treatment strategy.

BACKGROUND AND PURPOSE: Percutaneous nephrolithotomy (PCNL) is a well-accepted technique for removal of large or complex renal calculi. However, little attention has been paid to strategies for nephrostomy tube (NT) selection. We reviewed the reasons for selecting three types of NT after PCNL for large or complex stone disease. PATIENTS AND METHODS: A series of 106 consecutive renal units undergoing PCNL for stone burdens >2 cm by a single surgeon (JEL) were reviewed. Noncontrast CT (NCCT) was carried out on postoperative day 1, and secondary procedures were performed if fragments remained. The NTs studied were 8.5F and 10F Cope loops (CP), 20F reentry Malecot catheters (REM), and 20F circle loops (CL). Patient demographics, access site and number, complications, and stone type were examined. "Stone free" was defined as a negative NCCT or negative second-look PCNL. RESULTS: A total of 134 accesses were created in 106 renal units: 35 upper, 7 mid, and 92 lower; however, only 111 NTs were placed: 85 CP (76.6%), 19 REM (17.1%), and 7 CL (6.3%). Sixteen accesses were performed tubeless; all but two were in the upper pole. All 16 of these renal units had a concomitant NT placed in the lower pole. Multiple sites were accessed in 21 patients; 7 of these patients had CL placed. Five of ten patients with spinal-cord injury had REM/CL placed. Nineteen REM were placed: 10 for drainage of infection, and 9 for difficult anatomy. All renal units were rendered stone free: 31.1% with a single procedure and 95.6% with one or two procedures. There were no difficulties with drainage or access for secondary PCNL regardless of the NT employed. Complications included two hydrothoraces, one arteriovenous fistula, and one ureteral perforation. Three of four renal units in patients requiring transfusions underwent bilateral PCNL, and at least one renal unit required multiple accesses. Of kidneys with infection stones, 57.1% required REM or CL; only 12.0% of nonstruvite stones necessitated REM or CL. CONCLUSIONS: All patients having PCNL done for complex stone disease should have an NT placed; however, small (8.5F-10F) CP suffice in most cases and can provide greater patient comfort. To minimize pleural morbidity, tubeless upper-pole access should be considered if the kidney is judged to be stone free at the conclusion of PCNL. Circle loops are useful when multiple accesses are necessary, whereas REM are appropriate if access is difficult, gross residual stone remains, or pain is not an issue (i.e., spinal-cord injury).

Percutaneous nephrolithotomy for caliceal diverticular calculi: a novel single stage approach.

PURPOSE: Current percutaneous treatment of symptomatic caliceal diverticular calculi involves renal access, stone removal, dilation of the diverticular communication, fulguration of the cavity and placement of a nephrostomy tube. We reviewed the outcomes of patients undergoing a novel single stage percutaneous nephrolithotomy technique for radiopaque caliceal diverticular stones that eliminates ureteral catheterization and entry into the renal collecting system. MATERIALS AND METHODS: A total of 21 patients (8 male and 13 female including 1 bilateral) with a mean age of 42.4 years underwent percutaneous nephrolithotomy for caliceal diverticular stones from February 2001 to May 2003. Of the diverticula 12 were upper pole, 4 were interpolar and 6 were lower pole. Infracostal access was established by the urologist directly onto the radiopaque stones without the aid of a ureteral catheter. After balloon tract dilation a 30Fr Amplatz sheath was placed and following stone removal the diverticulum was fulgurated. The infundibulum was neither cannulated nor dilated. A 20Fr red rubber catheter or an 8.5Fr Cope loop was placed into the diverticulum. Stone-free status was assessed by noncontrast computerized tomography on postoperative day 1 (POD1). The drainage tube was removed if there was no urine drainage and the kidney was stone-free. Excretory urography was performed at 3 months to evaluate diverticular resolution. RESULTS: Of 21 patients 20 were discharged home tubeless on POD1 and 18 of 21 (85.7%) renal units were stone- free on POD1 noncontrast computerized tomography. Mean operative time was 58.5 minutes and mean stone burden was 138.9 mm. Mean stone diameter was 11.6 mm and mean diverticular diameter was 15.3 mm. Of 22 renal units 16 had followup excretory urography. All diverticula decreased in size and 14 (87.5%) had complete resolution. CONCLUSIONS: In patients with symptomatic radiopaque caliceal diverticular stones, a single stage procedure without the need for ureteral catheterization combined with direct infracostal diverticular puncture allows for a rapid procedure with little morbidity.

Crystal-associated nephropathy in patients with brushite nephrolithiasis.

BACKGROUND: We have biopsied the renal cortex and papillae of patients who form brushite renal stones asking if this unusual stone type is associated with specific tissue changes. We contrasted these with biopsies of 15 calcium oxalate stone formers, three stone formers with intestinal bypass, and four normal subjects. METHODS: We studied all ten brushite stone formers treated with percutaneous nephrolithotomy (PNL) during the past 3 years using digital video imaging of renal papillae, and obtained cortical and papillary biopsies. Biopsies were analyzed by light and electron microscopy, microinfrared spectroscopy, and electron diffraction. RESULTS: Apatite crystals plugged scattered terminal collecting ducts whose cells were injured or dead, and surrounding interstitium inflamed and fibrotic. White papillary deposits of interstitial apatite particles, so called Randall's plaque, were also present. Glomerular changes and cortical tubular atrophy and interstitial fibrosis were moderate to severe. CONCLUSION: Brushite stone formers combine the interstitial plaque of calcium oxalate stone formers with the collecting duct apatite plugs found in stone formers with intestinal bypass. Collecting duct injury and interstitial fibrosis are severe. Prominent cortical fibrosis, tubule atrophy, and glomerular pathology seem secondary to the collecting duct plugging. We believe crystallization obstructs and destroys terminal collecting duct segments thereby damaging nephrons, perhaps via intranephronal obstruction, and producing a hitherto unrecognized renal disease.

Stone formation is proportional to papillary surface coverage by Randall's plaque.

PURPOSE: Randall's plaques are common in calcium oxalate (CaOx) stone formers (SF). Plaque coverage correlates directly with urine calcium excretion and inversely with urine volume. We hypothesize that plaque coverage should increase proportionally with increasing stone number. We measured plaque areas in idiopathic CaOx stone formers and nonstone formers (NSF), and identified significant relationships with quantified stone histories. MATERIALS AND METHODS: A total of 13 SFs and 4 control NSFs underwent nephroscopic papillary mapping with representative still images and MPEG (Moving Pictures Experts Group) movies used to identify plaque and papillary borders. Stone histories were obtained through patient interviews, and from medical records and radiographs. The relationship of plaque coverage to clinical stone events was assessed by general multivariate linear modeling. Log transformation normalized the distribution of percent plaque coverage and stone number. RESULTS: Plaque surface area in SFs differed significantly from that in NSFs (p <0.0001). The duration of stone disease and the log transformed percent plaque coverage correlated significantly with the number of stones (0.677 and 0.620, p = 0.003 and 0.008, respectively). On multivariate analysis and correcting for the duration of stone disease total percent plaque coverage correlated significantly with the number of stones (R = 0.496, p = 0.05). Disease duration and plaque coverage did not correlate significantly (p = 0.257). CONCLUSIONS: Percent plaque coverage directly correlates with the number of stones formed even when corrected for the duration of stone disease. However, plaque coverage does not correlate with the duration of stone disease. These results support the hypothesis that the pathogenesis of CaOx stones begins with Randall's plaques.

Simultaneous holmium laser enucleation of prostate and upper-tract endourologic stone procedures.

BACKGROUND AND PURPOSE: The holmium laser is a versatile urologic tool. Its unique cutting and coagulating properties allow multiple procedures, such as stone fragmentation and laser enucleation of the prostate (HoLEP), to be performed with a single set-up. This paper reviews our experience with simultaneous HoLEP and endourologic upper-tract stone procedures. PATIENTS AND METHODS: We retrospectively reviewed all 11 patients (12 renal units) treated with the combined approach of HoLEP and an upper-tract endourologic procedure for stone disease. All patients initially underwent HoLEP, followed immediately by percutaneous nephrolithotomy (PCNL)(N=2), ureteroscopy (URS)(N=8), or both (N=1). The mean stone diameter was 34.7 mm for PCNL and 6.7 mm for URS. Outcome data and complications were recorded. RESULTS: The mean preoperative and postoperative American Urological Association Symptom Scores were 21.8 and 6.3, respectively. The mean prostatic specimen weight was 118 g (range 21-376 g), and the mean hospital stay was 1.4 days. For 10 patients with available prostatic specific antigen (PSA) data, the mean preoperative and postoperative values were 6.2 and 0.9 ng/mL, respectively. All patients were catheter free at discharge. All three PCNL patients were rendered stone free; all four URS patients who had radiographic follow-up were stone free. There were no short- or long-term complications, and no transfusions were necessary. CONCLUSIONS: Simultaneous HoLEP and laser lithotripsy are feasible, emphasizing the unique capabilities of the holmium laser. The hemostasis offered by HoLEP allows safe removal of prostatic tissue and urinary calculi, obviating multiple procedures.