Biomedical subjects
Publications and source records attributed to W Patrick Springhart.
We describe a simple and effective method using the Stone Cone to prevent migration of stone fragments into the ureter during percutaneous nephrolithotomy. This maneuver may reduce the need for antegrade ureteroscopy to remove residual fragments, thereby saving time and obviating the need for placement of an occlusion balloon.
Recent advances in fiber optics and digital technology have dramatically improved the ability of the urologic surgeon to accurately image and document endoscopic and laparoscopic procedures. In addition, the development of digital endoscopes has expanded the armamentarium of the endoscopic surgeon greatly. Finally, new virtual reality technology has allowed increased visualization during surgery and provides excellent training for surgeons. This article details new imaging and documentation technology currently utilized during urologic procedures.
BACKGROUND AND PURPOSE: Shockwave lithotripsy (SWL) has become a first-line intervention for treatment of nephrolithiasis. However, few studies have examined the effects of modifications in the method of shockwave energy administration on comminution efficiency. We propose that a gradual increase in output voltage will produce superior stone fragmentation in comparison with a constant or a decreasing output voltage by optimizing the stress wave and cavitation erosion forces on renal calculi. MATERIALS AND METHODS: BegoStone phantoms were implanted in the renal pelvis of 11 pigs that underwent SWL at a pulse repetition rate of 1 Hz. Animals in the increasing strategy group (N = 4) were subjected to 18, 20, and 22 kV for 600, 600, and 800 shocks, respectively. The second group (N = 4) received a decreasing strategy of 22, 20, and 18 kV for 800, 600, and 600 shocks, respectively. The third group (N = 3) received all 2000 shocks at 20 kV, mimicking the clinical protocol. RESULTS: A progressively decreasing strategy and constant output voltage produced a mean comminution efficiency, or percentage of stone fragments <2 mm, of 89.0% +/- 3.3% and 87.6% +/- 1.7%, respectively. The mean comminution efficiency was improved to 96.5% +/- 1.4% by using the increasing strategy (P = 0.01). CONCLUSIONS: A progressive increase in lithotripter output voltage during SWL can produce greater stone fragmentation than protocols employing constant or decreasing output voltage.
BACKGROUND AND PURPOSE: The management of acute renal colic is a problem commonly encountered by both urologists and emergency medicine physicians. The classic approach to managing uncomplicated acute renal colic involves hydration, along with imaging and pain control. Previous studies have suggested that hydration has a significant impact on patient comfort, as well as spontaneous stone passage. This study evaluated the effects of maintenance v forced hydration and its effect on the pain experienced from renal colic. PATIENTS AND METHODS: Forty male and 18 female patients with a mean age of 41 years suspected to have acute renal colic were identified in the emergency department. After screening and informed consent, the patients were enrolled in the study, and 43 patients were eventually available for analysis. Patients received intravenous (IV) analgesia, imaging with a noncontrast CT scan of abdomen and pelvis, and assignment to either forced IV hydration with 2 L of normal saline over 2 hours (N = 20) or minimal IV hydration at 20 mL of normal saline per hour (N = 23). A visual analog pain scale was completed hourly for a total of 4 hours. Demographic information, laboratory and imaging results, narcotic use in morphine equivalents (ME), and pain scores were recorded and compared. Spontaneous stone passage rates were also calculated by careful patient follow-up. Results were considered statistically significant at p < 0.05. RESULTS: Stone size was equivalent in the two treatment groups (p > 0.05). There was no difference in the narcotic requirement in ME (p = 0.644) between the two groups. Similarly, there was no difference in hourly pain score or stone-passage rates between the groups (p > 0.05). CONCLUSIONS: Treatment of uncomplicated renal colic has traditionally included vigorous intravenous hydration, as well as medications for the control of pain and nausea. Our data suggest that maintenance intravenous fluids are as efficacious as forced hydration with regard to patient pain perception and narcotic use. Moreover, it appears the state of hydration has little impact on stone passage.
OBJECTIVES: To review our experience with ureteroscopy in treating patients with renal calculi in anomalous kidneys and to evaluate the efficacy of this approach. METHODS: Eight patients with renal calculi in anomalous kidneys who were managed by ureteroscopic procedures were identified. Demographic information, preoperative stone burden, operative information (ureteroscope size, lithotrite used, instruments used, duration of surgery, complications, stenting), follow-up imaging, and complications were obtained from the medical record. This information was analyzed to determine the most frequently used instruments and stone-free rates. RESULTS: Our cohort consisted of 4 patients with horseshoe kidneys (HSK) and 4 patients with pelvic kidneys (PK) (6 male, 2 female, mean age, 50.6 years). The average preoperative stone burden of the 11 treated calculi was 1.4 cm, with 5 stones located in the renal pelvis, 2 in the upper pole, and 4 in lower pole calyces. A 7.5F flexible ureteroscope, holmium laser lithotripsy, and nitinol baskets and graspers were used in all patients. Six patients had complete clearance of the stone on postoperative imaging (75% HSK, 75% PK), with 88% of patients asymptomatic after their procedure. No patients required additional surgical intervention. CONCLUSIONS: Flexible ureteroscopy with holmium laser lithotripsy and the use of nitinol baskets and graspers provides a reasonable alternative to shock wave lithotripsy in the management of patients harboring renal calculi in anomalous kidneys. In addition, ureteroscopy can be considered a primary option for managing select patients with symptomatic stones in PKs before a percutaneous surgical approach.
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OBJECTIVES: To evaluate the effect of ureteral access sheaths (UASs) on stone-free rates (SFRs) during ureteroscopic treatment of renal calculi. Several advantages of UASs during flexible ureteroscopy have been documented. However, no study has evaluated their impact on SFRs. METHODS: We retrospectively reviewed all ureteroscopic cases for the management of renal stones performed at our Stone Center. Data were stratified according to the use or lack of use of the UAS. The groups were stratified by stone location within the kidney. Stone-free status was determined at 2 months postoperatively by either intravenous urography with tomograms or noncontrast renal computed tomography in patients with contrast allergies. RESULTS: A total of 256 ureteroscopic procedures for the removal of renal calculi were performed between 1997 and 2003 (173 with UAS and 83 without). The groups were similar in age, sex, and stone burden. Stents were placed in nearly 80% of patients. The lower renal pole represented the most common presenting location. Stone displacement with a ureteroscopic basket for efficient fragmentation was necessary in 34%. The overall SFR in the UAS group and non-UAS group was 79% and 67%, respectively (P = 0.042). The SFRs were improved for calculi in all portions of the kidney. CONCLUSIONS: In addition to facilitating ureteroscopic access, reducing costs, and lowering intrarenal pressures, the results of the current study suggest that UASs improve SFRs during the management of renal calculi. It is now our current practice to use the UAS routinely during ureteroscopic treatment of renal and upper ureteral calculi.
OBJECTIVES: To perform an analysis of currently available manufacturer data regarding the character of ureteroscope damage. The high costs associated with the repair of flexible and semirigid ureteroscopes are well documented. Increased knowledge of the etiology of ureteroscope damage should aid urologists in prolonging the lives of these delicate instruments. METHODS: We requested data from the four major ureteroscope manufacturers (ACMI, Olympus America, Karl Storz, and Richard Wolf) on the types, speculated causes, costs, and frequency of ureteroscope damage. The results were tabulated in a blinded fashion and analyzed for trends. We then formulated guidelines that could be applied by practicing urologists. RESULTS: For both flexible and semirigid ureteroscopes, the frequency of repair increased with decreasing ureteroscope diameter and increasing instrument length. The cost of the repair was generally greater for flexible ureteroscopes (mean 4597 dollars) than for semirigid ureteroscopes (mean 2437 dollars). The major causes of flexible ureteroscope damage were working channel damage from laser burn or instrument passage and extreme scope deflection with an indwelling instrument. The primary reasons for semirigid ureteroscope repair included overtorquing and improper handling in the operating room and during sterile processing. CONCLUSIONS: Urologists can minimize the repair costs of flexible and semirigid ureteroscopes by taking precautions to eliminate laser fiber-induced damage and by avoiding overdeflection. Improved storage and handling of these instruments is also necessary. Although small-diameter ureteroscopes are favorable because of their increased mobility and ease of passage, physician and staff awareness of their increased fragility is vital in maximizing the longevity of these commonly used instruments.
PURPOSE: We report the results of a controlled survival study in a porcine model investigating Tisseel or a combination of FloSeal and Tisseel in dealing with vascular and collecting-system injury during partial nephrectomy. MATERIALS AND METHODS: We performed an open right lower-pole partial nephrectomy on 15 large female pigs. The defect was repaired using standard open techniques (N = 5; controls), Tisseel only (N = 6; group I), or FloSeal followed by Tisseel (N = 4; group II). A Jackson-Pratt drain was placed. Nephrectomy and retrograde pyelography were performed at 1 week. RESULTS: Operative times were shorter in both study groups, achieving statistical significance in group I (P = 0.008). Warm-ischemia times were significantly improved in both study groups (P = 0.029 and P = 0.00005 in groups I and II, respectively). Time to hemostasis was significantly shorter in group II only (P = 0.002) but approached significance in Group I as well (P = 0.09). Estimated blood loss was not significantly different from the controls in either group. When Tisseel was placed alone after hilar control, hematoma formation under the Tisseel was noted on release of the hilar clamp. After 1 week, there was one urinoma and three urine leaks in the control group. In group I, there was one urinoma and four urine leaks, and there was only one urine leak and no urinomas in group II. There were no hematomas in any of the groups. CONCLUSIONS: Tisseel alone is not adequate for either hemostasis or management of major collecting-system injury. FloSeal capped with Tisseel appears sufficient to control major vascular and collecting-system injuries without adjunctive surgical measures. A proposed technique for laparoscopic partial nephrectomy without reconstructive techniques is presented that warrants clinical study.
PURPOSE: The frequency doubled, double pulse Nd:YAG (FREDDY) laser (World of Medicine, Berlin, Germany) functions through the generation of a plasma bubble. Upon bubble collapse a mechanical shock wave is generated, causing stone fragmentation. This mechanism of action is in contrast to the holmium laser, which cause stone destruction by vaporization. Observed clinical stone retropulsion and fragmentation with the FREDDY and holmium lasers has prompted a series of in vitro experiments designed to compare laser induced retropulsion and fragmentation with those of a holmium laser and pneumatic lithotrite. MATERIALS AND METHODS: For retropulsion a hands-off underwater laboratory setup, including a horizontally oriented silicone tube 1.3 cm in diameter and a holder to keep the stone phantom in contact with the quartz laser fiber or pneumatic probe, was used. Previously weighed, cylindrical Bego stone phantoms (Bego USA, Smithfield, Rhode Island) were placed in the apparatus. Stone fragmentation was performed with the FREDDY or holmium laser, or the pneumatic lithotripter. The FREDDY and holmium lasers were tested at similar pulse energy and frequency settings. As a standard for comparison, a pneumatic lithotrite was tested with a semirigid probe and single pulse settings of 100, 200 and 300 kPa. Stone phantoms underwent 30 shocks per setting. Mean net retropulsion, defined as the final resting point of the stone, as determined by direct measurement, was recorded for each setting. For fragmentation plaster of Paris stone phantoms of known weights were used to compare the fragmentation ability of each laser. Stones phantoms were placed in a hands-off underwater setup, consisting of an inverted silicon syringe and holder immersed in tap water. The laser fiber (365 microm for the holmium and 280 microm for the FREDDY) was placed through the tip of the syringe in contact with the stone phantom. A total of 24 stones were divided into 4 groups of 6 per group. Two groups were fragmented with the FREDDY laser at 300 and 400 J total energy. The other 2 groups were fragmented using the holmium laser at 300 and 480 J total energy. Fragmentation efficiency was determined as percent weight loss. RESULTS: For retropulsion at 160 mJ the FREDDY laser caused stone retropulsion to a mean distance of 7.6, 8.1 and 6.8 cm at settings of 5, 10 and 15 Hz, respectively. At 0.8 J the holmium laser retropulsed the stone to a mean distance of 3.3 and 4.9 cm at settings of 5 and 10 Hz, respectively. The pneumatic device caused stone retropulsion a mean distance of 8.5, 9.9 and 13.8 cm at pressure settings of 100, 200 and 300 kPa, respectively. The FREDDY laser generally caused less retropulsion than the pneumatic device, although this difference was only significant at the highest pneumatic lithoclast setting (p <0.05). At clinically relevant settings the FREDDY laser caused significantly more retropulsion than the holmium laser (p <0.05). For fragmentation at total energy settings of 300 and 400 J the FREDDY laser resulted in 44.9% and 86.8% weight loss, respectively (p <0.05). At settings of 300 and 480 J the holmium:YAG laser resulted in 3.3% and 7.1% weight loss, respectively (p <0.05). CONCLUSIONS: At lower frequency settings stone retropulsion was significantly greater with the FREDDY laser compared with the holmium laser. However, retropulsion was significantly less than that caused by the pneumatic lithotripter at all settings. Therefore, we recommend the use of an occlusive device, such as the Stone Cone (Boston Scientific, Natick, Massachusetts) proximal to the calculus during intracorporeal ureteral lithotripsy and in the ureteropelvic junction during percutaneous laser nephrostolithotomy. In vitro stone fragmentation was significantly greater with the FREDDY laser than with the holmium:YAG laser, suggesting that the FREDDY may offer a low cost alternative to the holmium:YAG laser lithotrite in select patients.
PURPOSE: Nephrolithiasis disproportionately affects white patients. However, recent studies propose an increase in the incidence of stone disease in nonwhite populations. We compared the metabolic risk factors of ethnically disparate stone formers from the same geographic region. MATERIALS AND METHODS: A retrospective review of 1,141 patients identified 98 (9%) nonwhite stone formers. Of these individuals 60 underwent a comprehensive metabolic evaluation, comprising 44 black, 8 Asian and 8 Hispanic patients. A similar sex and age matched group of 66 white stone forming patients were also identified for comparative analysis. Stone analyses were recorded when available. Urinary metabolic abnormalities were defined as low urine volume-urine volume less than 2,000 cc, gouty diathesis-pH 5.5 or less (normal level 5.5 to 6.5), hypercalciuria-calcium greater than 200 mg, hyperoxaluria-oxalate greater than 45 mg, hyperuricosuria-uric acid greater than 600 mg, hypocitraturia-citrate less than 600 mg and purine gluttony-sulfate greater than 20 mg. RESULTS: The incidence of metabolic abnormalities was surprisingly similar between the white and nonwhite stone formers. Whites have a higher prevalence of hypercalciuria compared with nonwhites (67% vs 25%, respectively, p <0.01). This comparison persisted when the white group was compared with individual ethnic groups (25% in each group). Whites also displayed a higher mean urinary calcium level (233 mg) than their nonwhite counterparts overall (146 mg), specifically with respect to blacks (146 mg, p <0.01). Asians had higher urine volumes with respect to whites and blacks (p <0.01) and, therefore, a decreased prevalence of low urine volumes (37.5% vs 74.2% and 79.5%, respectively). Hypocitraturia, hyperuricosuria, hyperoxaluria, gouty diathesis and high sulfate levels were equally represented among all ethnic groups. CONCLUSIONS: Although there appears to be a predominance of stone disease among whites, all racial groups demonstrated a remarkable similarity in the incidence of underlying metabolic abnormalities. These results suggest that dietary and environmental factors may be as important as ethnicity in the etiology of stone disease.
OBJECTIVE: To present early experience in managing complex renal calculi using a combined ureteroscopic and percutaneous approach, as complex and branched renal calculi often require multiple access tracts during percutaneous nephrolithotomy (PNL), and the combined use of flexible ureteroscopy and PNL has the potential to reduce the inherent morbidity of several tracts. PATIENTS AND METHODS: The study included seven patients (mean age 54 years) with multiple, branched, large-volume renal calculi suitable for management with PNL. Preoperative data, including patient demographics, stone location and stone surface area, were recorded. After informed consent, the patients underwent combined PNL and ureteroscopy in one session. Intraoperative data, including the location of PNL puncture sites, operative duration and complications, were analysed. Stone-free rates were determined by follow-up imaging at 3 months. RESULTS: All patients had either two or more stones in separate locations in the collecting system, or staghorn stones involving multiple calyces. The mean stone burden was 666 mm(2). All patients had only one percutaneous access tract. The mean operative duration was 142 min and the mean blood loss 79 mL. Two patients had small residual stones (< 3 mm), that required ureteroscopic intervention as they failed to pass spontaneously by 3 months after the initial combined procedure. The convalescence was similar to that in our current PNL practice; imaging showed that five of the patients were stone-free. CONCLUSIONS: Combined PNL and ureteroscopic management can effectively reduce the number of percutaneous access tracts which would otherwise be required for managing complex and branched renal calculi, as stones in an unfavourable location relative to the access tract can be relocated and fragmented within easy reach of the single nephrostomy tract. This manoeuvre reduces potential patient morbidity and blood loss but with no significant effect on stone-free rates and operative durations.
PURPOSE OF REVIEW: Stone disease continues to plague humankind. Recent innovations in minimally invasive surgery, however, have decreased morbidity for the treatment of lithiasis, once only amenable to open surgical techniques. These advances in stone management have also been paralleled in the radiographic armamentarium. Herein, we describe the evolution of initial radiographic workup for urolithiasis, from abdominal radiograph to three-dimensional computed tomography and some of the novel applications thereof. RECENT FINDINGS: Previously, abdominal radiography was the only modality available for the visualization of calculi. Subsequently, the development of intravenous contrast aided in evaluating renal function, detecting the presence and location of obstruction, and in identifying filling defects. Most recently, prospective randomized trials have demonstrated improved sensitivity and specificity using noncontrast helical computed tomography rather than intravenous pyelogram with regard to the initial evaluation of acute flank pain. Further attempts to lower the overall radiation dose without compromising efficacy have also been introduced. Currently, the volume of calculus disease can be better quantified and somewhat qualified from three-dimensional computer software, thereby optimizing stone management. SUMMARY: Considerable progress has been made using minimally invasive techniques in the treatment of nephrolithiasis. Furthermore, advances in radiographic computer hard- and software applications allow for a rapid acquisition time and improved image quality without sacrificing diagnostic accuracy. In time, it is likely that the combination of these enhanced imaging modalities will lead to an improvement in stone localization, fragmentation and stone-free rates.
PURPOSE: Pneumatic lithotripsy has been shown to be an effective and safe intracorporeal lithotripsy modality for renal and ureteral calculi, capable of fragmenting stones of all compositions. We determined the in vitro stone fragmentation abilities of the 0.5 mm flexible pneumatic lithotripsy probe when inserted through the working channel of 2, 7.5Fr flexible ureteroscope designs (straight working channel and offset working channel at approximately 30 degrees from the long axis of the endoscope). The velocity and displacement of the pneumatic probe tip were also evaluated with the probe inserted through each endoscope. MATERIALS AND METHODS: The 0.5 mm (1.5Fr) stainless steel probe was tested at 5 deflection angles, namely 0, 12, 24, 33 and 48 degrees, at a pneumatic pressure of 2.5 bar when inserted through the offset and straight working channel ureteroscopes. A noncontact optical laser system was used to measure or calculate the displacement and velocity of the 0.5 mm probe tip at each angle of deflection with the 2 ureteroscopes. Fragmentation at all deflection angles was assessed using plaster of Paris stone phantoms with the pneumatic device on continuous mode at 2.5 bar pressure for 30 seconds. Stones were weighed after each fragmentation cycle and the percent weight lost was determined. Comparisons were made between the 2 ureteroscopes at each angle. RESULTS: Probe tip displacement was significantly better through the straight channel ureteroscope with 30% improvement at all angles tested compared to the offset channel. Moreover, a substantial decrement in tip displacement was noted as the angle of deflection increased regardless of the endoscope used. Conversely tip velocity was relatively unchanged throughout the study and it was equivalent from straight to offset channel measurements. Phantom stone fragmentation correlated inversely with the severity of the deflection angle. An approximately 80% loss of fragmentation ability was noted as the angle increased from 0 to 48 degrees. Although the pneumatic device performed better through the straight channel scope, a similar percent loss in fragmentation from 0 to 48 degrees was seen when using either endoscope. CONCLUSIONS: The flexible pneumatic 0.5 mm lithotripsy probe appears to be best used through a straight channel flexible ureteroscope, out performing use through the offset channel scope at all angles of deflection. Tip displacement and fragmentation ability were inversely related to the degree of active deflection as the angle increased from 0 to 48 degrees. Use of the flexible pneumatic probe to aid in managing renal or proximal ureteral calculi may be limited until an improved probe can be developed, allowing complete and unencumbered fragmentation throughout all angles of deflection.