Image-guided surgical planning of percutaneous nephrolithotomy with patient-specific CTRs.

PURPOSE: We propose the utilization of patient-specific concentric-tube robots (CTRs) whose designs are optimized to enhance their volumetric reachability of the renal stone, thus reducing the morbidities associated with percutaneous nephrolithotomy procedures. By employing a nested optimization-driven scheme, this work aims to determine a single surgical tract through which the patient-tailored CTR is deployed. We carry out a sensitivity analysis on the combined percutaneous access and optimized CTR design with respect to breathing-induced excursion of the kidneys based on preoperative images. Further, an investigation is also performed of the appropriateness and effectiveness of the percutaneous access provided by the proposed algorithm compared to that of an expert urologist. METHODS: The method is based on an ellipsoidal approximation to the renal calculi and a grid search over candidate skin areas and available renal calyces using an anatomically constrained kinematic mapping of the CTR. Percutaneous access is selected for collision-free CTR deployment to the centroid of the stones with minimal positional error at the renal calyx. Further optimization of the CTR design results in a robot tailored to the therapeutic anatomical features of each clinical case. The study examined 14 sets of clinical data of PCNL patients, analyzing stone reachability using preoperative images and breathing-induced motions of the kidney. An experienced urologist qualitatively assessed the adequacy of percutaneous access generated by the algorithm. RESULTS: An assessment conducted by an expert urologist found that the percutaneous accesses produced by the proposed approach were found to be comparable to those chosen by the expert surgeon in most clinical cases. The simulated results demonstrated a mean volume coverage of [Formula: see text] for static anatomy and [Formula: see text] and [Formula: see text] when considering a 1 cm excursion of the kidney in the craniocaudal directions due to respiration or tool-tissue interaction. CONCLUSION: The optimization-driven scheme for determining a single tract surgical plan, coupled with the use of a patient-specific CTR, shows promising results for improving percutaneous access in PCNL procedures. This approach clearly shows the potential for enhancing the quality and suitability of percutaneous accesses, addressing the challenges posed by staghorn and non-staghorn stones during PCNL procedures. Further research involving clinical validation is necessary to confirm these findings and explore the potential clinical benefits of the approach.

On Surgical Planning of Percutaneous Nephrolithotomy with Patient-Specific CTRs.

Percutaneous nephrolithotomy (PCNL) is considered a first-choice minimally invasive procedure for treating kidney stones larger than 2 cm. It yields higher stone-free rates than other minimally invasive techniques and is employed when extracorporeal shock wave lithotripsy or uteroscopy are, for instance, infeasible. Using this technique, surgeons create a tract through which a scope is inserted for gaining access to the stones. Traditional PCNL tools, however, present limited maneuverability, may require multiple punctures and often lead to excessive torquing of the instruments which can damage the kidney parenchyma and thus increase the risk of hemorrhage. We approach this problem by proposing a nested optimization-driven scheme for determining a single tract surgical plan along which a patient-specific concentric-tube robot (CTR) is deployed so as to enhance manipulability along the most dominant directions of the stone presentations. The approach is illustrated with seven sets of clinical data from patients who underwent PCNL. The simulated results may set the stage for achieving higher stone-free rates through single tract PCNL interventions while decreasing blood loss.

Use of the Quick Sequential Organ Failure Assessment Score for Prediction of Intensive Care Unit Admission Due to Septic Shock after Percutaneous Nephrolithotomy: A Multicenter Study.

PURPOSE: Recent studies have demonstrated that quick sequential organ failure assessment criteria may be more accurate than systemic inflammatory response syndrome criteria to predict postoperative sepsis. In this study we evaluated the ability of these 2 criteria to predict septic shock after percutaneous nephrolithotomy. MATERIALS AND METHODS: We performed a retrospective multicenter study in 320 patients who underwent percutaneous nephrolithotomy at a total of 8 institutions. The criteria for quick sequential organ failure assessment and systemic inflammatory response syndrome were collected 24 hours postoperatively. The study primary outcome was postoperative septic shock. Secondary outcomes included 30 and 90-day emergency department visits, and the hospital readmission rate. RESULTS: Three of the 320 patients (0.9%) met the criteria for postoperative septic shock. These 3 patients had positive criteria for quick sequential organ failure assessment and systemic inflammatory response syndrome. Of the entire cohort 23 patients (7%) met quick sequential organ failure assessment criteria and 103 (32%) met systemic inflammatory response syndrome criteria. Specificity for postoperative sepsis was significantly higher for quick sequential organ failure assessment than for systemic inflammatory response syndrome (93.3% vs 68.4%, McNemar test p <0.001). The positive predictive value was 13% for quick sequential organ failure assessment criteria and 2.9% for systemic inflammatory response syndrome criteria. On multivariate logistic regression systemic inflammatory response syndrome criteria significantly predicted an increased probability of the patient receiving a transfusion (ß = 1.234, p <0.001). Positive quick sequential organ failure assessment criteria significantly predicted an increased probability of an emergency department visit within 30 days (ß = 1.495, p <0.05), operative complications (ß = 1.811, p <0.001) and transfusions (p <0.001). The main limitation of the study is that it was retrospective. CONCLUSIONS: Quick sequential organ failure assessment criteria were superior to systemic inflammatory response syndrome criteria to predict infectious complications after percutaneous nephrolithotomy.

Minimally invasive surgical treatment for kidney stone disease.

Minimally invasive interventions for stone disease in the United States are mainly founded on 3 surgical procedures: extracorporeal shock wave lithotripsy, ureteroscopic lithotripsy, and percutaneous nephrolithotomy. With the advancement of technology, treatment has shifted toward less invasive strategies and away from open or laparoscopic surgery. The treatment chosen for a patient with stones is based on the stone and patient characteristics. Each of the minimally invasive techniques uses an imaging source, either fluoroscopy or ultrasound, to localize the stone and an energy source to fragment the stone. Extracorporeal shock wave lithotripsy uses a shock wave energy source generated outside the body to fragment the stone. In contrast, with ureteroscopy, laser energy is placed directly on the stone using a ureteroscope that visualizes the stone. Percutaneous nephrolithotomy requires dilation of a tract through the back into the renal pelvis so that instruments can be inserted directly onto the stone to fragment or pulverize it. The success of the surgical intervention relies on performing the least invasive technique with the highest success of stone removal.

Positive stone culture is associated with a higher rate of sepsis after endourological procedures.

The purpose of this study was to determine if there is a correlation between urine and/or stone cultures with postoperative sepsis in patients treated for renal and ureteral calculi. Three hundred and twenty-eight consecutive patients who underwent percutaneous nephrolithotomy (PCNL) or ureteroscopy from 2006 to 2009 were identified, all of whom had a stone culture obtained during surgery. All had a preoperative urine culture. Two hundred and seventy-four underwent ureteroscopy and 54 PCNL. All patients had either negative preoperative urine cultures or were given preoperative antibiotics for 1-7 days prior to surgery. Stone fragments were obtained during the procedure and sent for analysis. The primary endpoint was sepsis. Of 328 patients, 3 % (11/328) developed postoperative sepsis. 73 % (8/11) had positive stone cultures, while none had a positive preoperative urine culture. 8 % (8/96) with positive stone cultures and 1 % (3/232) with negative stone cultures developed sepsis (p = 0.003). The stone culture grew the same pathogen as the urine culture obtained on readmission in 64 % (7/11) of the patients, while 9 % (1/11) of preoperative urine cultures correlated with the readmission pathogen (p = 0.02). The pathogen causing infection had a significantly higher correlation with the organism grown on stone culture than the preoperative urine culture. The patients who developed sepsis did so despite preoperative antibiotics, and the pathogen grown on the preoperative urine culture was different from that seen post operatively. These results suggest that stone culture is more informative than preoperative urine culture for determining treatment of postoperative sepsis.

Ureteral stenting and retrograde pyelography in the office: clinical outcomes, cost effectiveness, and time savings.

OBJECTIVES: To examine the clinical outcomes and cost-effectiveness of endourologic procedures performed in the office using standard fluoroscopy and topical anesthesia. METHODS: We performed a retrospective review of all patients who underwent primary ureteral stent placement, ureteral stent exchange, or ureteral catheterization with retrograde pyeolography or Bacillus Calmette-Guerin (BCG) instillation under fluoroscopic guidance in the office. For an evaluation of potential time savings, we compared this to a cohort of similar procedures performed in the operating room during the same time period. RESULTS: Procedures were attempted in 65 renal units in 38 patients (13 male, 25 female) with a mean age of 62.2 years (range 29.1-95.4 years). Primary ureteral stent placement was successful in 23/24 (95.8%) renal units. Ureteral stent exchange was successful in 19/22 (86.4%) renal units. Ureteral catheterization with retrograde pyelography or BCG instillation was successful in 19/19 (100%) renal units. The total cost savings for the 38 patients in this study, including excess cost from failure in the office, was approximately $91,496, with an average cost savings of $1,551 per procedure. Office-based procedures were associated with a nearly three-fold reduction in total hospital time as a result of reduced periprocedure waiting times. CONCLUSIONS: Ureteral stent placement, ureteral stent exchange, and ureteral catheterization can be performed safely and effectively in the office in both men and women. This avoids general anesthesia and provides significant savings of time and cost for both patients and the health care system.

The effect of delayed percutaneous nephrolithotomy on the risk of bacteremia and sepsis in patients with neuromuscular disorders.

PURPOSE: To determine whether a delayed percutaneous nephrolithotomy (PCNL) reduces the rate of bacteremia/sepsis in patients with neuromuscular disorders. Patients with neuromuscular disorders are at higher risk of developing complications after PCNL. One strategy to reduce the risk of infectious complications is to place a percutaneous nephrostomy tube at least 24 h prior to performing PCNL. We analyzed the rates of bacteremia/sepsis in patients with neuromuscular disorders who had access on the day of PCNL (same-day) versus more than 24 h prior to the treatment for the stone (delayed). MATERIALS AND METHODS: We identified 246 consecutive patients who underwent PCNL at our institution between 8/2003 and 8/2008, 35 of whom (14%) had neuromuscular disorders. The primary end point was postoperative bacteremia (fever and positive blood culture) or sepsis (SIRS and documented infection), which was compared between those who had percutaneous access on the day of surgery versus those who had access at least 24 h prior to the operative event. All patients had negative urine cultures preoperatively or were treated with antibiotics for 4-7 days prior to the surgery for a positive preoperative urine culture. RESULTS: The neuromuscular disorders in the 35 patients were multiple sclerosis (16), spina bifida (10), quadriplegia (4), paraplegia/Guillain-Barre (3), and cerebral palsy (2). The rate of bacteremia/sepsis among patients with neuromuscular disorders was 14%. The rate of sepsis/bacteremia was 26% for same-day PCNL versus 0% for delayed PCNL (OR 8.4, p = 0.05). CONCLUSIONS: Delayed PCNL results in lower rates of bacteremia and/or sepsis in patients with neuromuscular disorders.

Preventing migration of stones during fragmentation with thermosensitive polymer.

PURPOSE: To define a method of stabilizing stones during extracorporeal (SWL) and intracorporeal lithotripsy with a thermosensitive polymer. MATERIALS AND METHODS: Using a thermosensitive polymer that is either a liquid or a gel, depending on the temperature, both calcium oxalate and plaster of Paris phantom stones were placed in the polymer gel or saline, and SWL was performed. Comparisons were made between the effectiveness of the fragmentation in the two media. Also, in-vivo studies using the polymer to prevent migration of ureteral stones were performed in swine. Electrohydraulic lithotripsy was used on a small stone implanted in the distal ureter with the polymer instilled proximally. Once in the ureter, the polymer converted to a gel. After completion of the procedure, the polymer was restored to a liquid form by infusion of cold saline and expelled from the ureter. Three of the pigs underwent treatment of the stone, convalesced for 7 days, and then had urine collections from both ureters to compare the glomerular filtration rates, fractional sodium excretion, urine/plasma creatinine ratio, and urine/plasma urea ratio on the treated and the contralateral (control) sides. RESULTS: The polymer did not enhance fragmentation when used with SWL but prevented stone migration in the in-vivo studies. The physiologic parameters were not significantly different on the treated and the control sides. The polymer was easily removed from the ureter by infusing cold water. CONCLUSION: The use of this thermosensitive polymer proximal to ureteral stones prevents migration and is not traumatic to the ureter.

Repeat knot formation in a patient with an indwelling ureteral stent.

A patient treated for nephrolithiasis formed knots in 2 occasions, in 2 separate indwelling ureteral stents. This rare complication may make stent removal difficult. To our knowledge, this is the first case report of repeat knot formation in a single patient.

Repeat knot formation in a patient with an indwelling ureteral stent

A patient treated for nephrolithiasis formed knots in 2 occasions, in 2 separate indwelling ureteral stents. This rare complication may make stent removal difficult. To our knowledge, this is the first case report of repeat knot formation in a single patient.

Organ conservation in invasive bladder cancer by transurethral resection, chemotherapy and radiation: results of a urodynamic and quality of life study on long-term survivors.

PURPOSE: Transurethral resection, chemotherapy and radiation with salvage cystectomy may be used as alternatives to immediate radical cystectomy in the management of invasive bladder cancer. Concern exists about the function of the retained bladder after such therapy. MATERIALS AND METHODS: Of 221 patients with clinical T2-4a bladder cancer treated at Massachusetts General Hospital from 1986 to 2000 with trimodality therapy, 71 were alive with native bladders and disease-free in 2001. These patients were asked to undergo a urodynamic study and to complete a quality of life questionnaire. A total of 69% participated in some component of this study with a median time from trimodality therapy of 6.3 years (range 1.6 to 14.9). RESULTS: Of 32 patients 24 had normally functioning bladders by urodynamic study. Decreased bladder compliance was seen in 7. Bladder hypersensitivity, involuntary detrusor contractions and incontinence were present in 2 women. The questionnaire showed that flow symptoms occurred in 6%, urgency in 15% and control problems in 19%. Of all women 11% wore pads. Distress from urinary symptoms was half as common as prevalence. Bowel symptoms occurred in 22% with 14% recording any level of distress. The majority of men retained sexual function. Global health related quality of life was high. CONCLUSIONS: The majority of patients treated with trimodality therapy retain good bladder function. A fifth have evidence of bowel dysfunction.