A biological model to teach percutaneous nephrolithotomy technique with ultrasound- and fluoroscopy-guided access

PURPOSE: To develop a training model for simulated percutaneous nephrolithotomy (PCNL) under ultrasound and fluoroscopy-guided access. MATERIALS AND METHODS: The laboratory model for PCNL described by Hammond and associates (J Urol 2004;172:1950-1952) was modified. We used an ex-vivo perfused porcine kidney (freshly removed after commercial slaughtering), a chicken carcass (supermarket), as well as the standard equipment for PCNL. For imaging, ultrasound (7.5 MHz) and a fluoroscopy unit are necessary. Artificial stone material is implanted in the renal pelvis. The ureter is cannulated for retrograde pyelography and the renal artery and vein for continuous perfusion. The perfused kidney surrounded by ultrasound gel is placed in the eviscerated chicken carcass. RESULTS: The model is low cost and simple to set up, with a preparation time of about 15 minutes. The equipment used in clinical practice can be employed for renal access, tract dilation, nephroscopy, stone disintegration, and stone removal. Imaging is feasible under fluoroscopic and ultrasound guidance. CONCLUSIONS: This biological training model simulates realistically the clinical procedure of PCNL under ultrasound and fluoroscopic guidance. Teaching and skill acquisition are practicable.     

机器人辅助椎弓根置钉治疗老年脊柱退行性疾病的Meta分析

目的通过Meta分析比较机器人辅助与透视引导椎弓根置钉在治疗老年脊柱退行性疾病时的准确性及安全性差异。 方法检索2008年04月至2018年04月国内外已发表的临床对照研究。所检索的数据库包括Embase、Pubmed、中国知网、维普、万方等数据库。依据检索策略,共检索到相关文献377篇,并最终纳入10篇外文文献,1篇中文文献。提取数据后,采用Review Manager 5.3软件进行数据分析。 结果椎弓根置钉治疗老年脊柱退行性疾病时,机器人辅助组的置钉准确度优于透视引导组（95% CI：1.38~2.43,P<0.001）,机器人辅助组的不良事件发生率（95% CI：0.22~0.90,P=0.02）及翻修率（95% CI：0.17~0.91,P=0.03）均少于透视引导组,而透视引导组术中辐射强度要少于机器人辅助组（95% CI：0.09~0.89,P=0.02）,余结局指标两组差异均无统计学意义。 结论在治疗老年脊柱退行性疾病时,机器人辅助椎弓根螺钉置入较传统透视引导置入具有更高的置钉准确度、更低的不良事件发生率。虽然术中辐射强度略高于透视引导组,但是机器人辅助技术仍不失为是一种安全可靠的治疗选择。     

Factors affecting blood loss during percutaneous nephrolithotomy: prospective study

BACKGROUND AND PURPOSE: Bleeding is a major concern during percutaneous nephrolithotomy (PCNL), especially with the use of multiple tracts. This prospective study aimed to identify factors affecting blood loss during PCNL. PATIENTS AND METHODS: Data were collected prospectively from 236 patients undergoing 301 PCNL procedures at our institute since June 2002. Blood loss was estimated by the postoperative drop in hemoglobin factored by the quantity of any blood transfusion. Various patient-related and intraoperative factors were assessed for association with total blood loss or blood transfusion requirement using stepwise multivariate regression analysis. RESULTS: The average hemoglobin drop was 1.68 +/- 1.23 g/dL. Stepwise multivariate regression analysis showed that the occurrence of operative complications (P < 0.0001), mature nephrostomy tract (P < 0.0001), operative time (P < 0.0001), method of access guidance (fluoroscopy v ultrasound) (P = 0.0001), method of tract dilatation (P = 0.0001), multiple (> or =2) tracts (P = 0.003), size of the tract (P = 0.001), renal parenchymal thickness (P = 0.05), and diabetes (P = 0.05) were significant predictors of blood loss. The overall blood transfusion rate for all patients was 7.9%. Preoperative hemoglobin, multiple tracts, stone size, and total blood loss were significant in predicting perioperative blood transfusion requirement. Factors such as age, hypertension, renal insufficiency, urinary infection, the degree of hydronephrosis, stone bulk, and the function of the ipsilateral renal unit did not have any effect on the blood loss. Technical factors such as the operating surgeon and the calix of entry also did not affect the blood loss. CONCLUSIONS: Diabetes, multiple-tract procedures, prolonged operative time, and the occurrence of intraoperative complications are associated with significantly increased blood loss. Atrophic parenchyma and past ipsilateral intervention are associated with reduced blood loss. On the basis of this evidence, maneuvers that may reduce blood loss and transfusion rate include ultrasound-guided access, use of Amplatz or balloon dilatation systems, reducing the operative time, and staging the procedure in cases of a large stone burden or intraoperative complications. Reducing the tract size in pediatric cases, nonhydronephrotic systems and those with a narrow infundibulum, and secondary tracts in a multiple-tract procedure may also reduce blood loss during PCNL.     

Robotic percutaneous access to the kidney: comparison with standard manual access

PURPOSE: To evaluate the efficiency, accuracy, and safety of robotic percutaneous access to the kidney (PAKY) for percutaneous nephrolithotomy in comparison with conventional manual techniques. MATERIALS AND METHODS: We compared the intraoperative access variables (number of access attempts, time to successful access, estimated blood loss, complications) of 23 patients who underwent robotic PAKY with the remote center of motion device (PAKY-RCM) with the same data from a contemporaneous series of 23 patients who underwent conventional manual percutaneous access to the kidney. The PAKY-RCM incorporates a robotic arm and a friction transmission with axial loading system to accurately position and insert a standard 18-gauge needle percutaneously into the kidney. The blood loss during percutaneous access was estimated on a four-point scale (1 = minimal to 4 = large). The color of effluent urine was graded on a four-point scale (1 = clear to 4 = red). RESULTS: The mean target calix width was 13.5 +/- 9.2 mm in the robotic group and 12.2 +/- 4.5 mm in the manual group (P = 0.57). When comparing PAKY-RCM with standard manual techniques, the mean number of attempts was 2.2 +/- 1.6 v 3.2 +/- 2.5 (P = 0.14), time to access was 10.4 +/- 6.5 minutes v 15.1 +/- 8.8 minutes (P = 0.06), estimated blood loss score was 1.3 +/- 0.49 v 1.7 +/- 0.66 (P = 0.14), and color of effluent urine following access was 2.0 +/- 0.90 v 2.1 +/- 0.7 (P = 0.82). The PAKY-RCM was successful in obtaining access in 87% (20 of 23) of cases. The other three patients (13%) required conversion to manual techniques. There were no major intraoperative complications in either group. CONCLUSIONS: Robotic PAKY is a feasible, safe, and efficacious method of obtaining renal access for nephrolithotomy. The number of attempts and time to access were comparable to those of standard manual percutaneous access techniques. These findings provide the groundwork for the development of a completely automated robot-assisted percutaneous renal access device.     

Laparoscopic ureterocalicostomy: development of a technique simplified by application of Nitinol clips and a wet monopolar electrosurgery device

PURPOSE: We developed a technique for laparoscopic ureterocalicostomy with the use of intracorporeal suturing and subsequently simplified the technique by application of experimental Nitinol clips. MATERIALS AND METHODS: We performed laparoscopic ureterocalicostomy on 16 domestic swine divided into four groups of four animals each. The kidney was exposed laparoscopically, and the renal artery was atraumatically clamped. The lower pole of the kidney was amputated to expose a lower-pole calix, and hemostasis of the cut renal surface was obtained with a wet monopolar electrosurgical device (Floating Ball device [FB]; TissueLink, Dover, NH). Anastomosis of the ureter to the lower-pole calix was performed over a guidewire using 3-0 Vicryl suture in group 1 and Nitinol clips in group 3. A double-J ureteral stent was then deployed retrograde under fluoroscopic guidance. In addition, we evaluated the use of fibrin glue as a sealant over the sutured or clipped anastomotic site (groups 2 and 4, respectively). Ureteral stents were removed after 3 weeks, and the animals were evaluated and sacrificed after an additional 3 weeks. RESULTS: Laparoscopic ureterocalicostomy was completed in all 16 animals. In each case, excellent renal parenchymal hemostasis was obtained with the FB device, with a mean hemostasis time of 4.1 minutes. The mean anastomotic time with standard suture reconstruction was 37.1 +/- 5.4 minutes, while the anastomotic time with the Nitinol clips was 29.0 +/- 8.0 minutes (P = 0.0339). Retrograde pyelograms in groups 1 and 3 (no fibrin glue) showed a patent anastomosis with no hydronephrosis in three of the four animals in each group. One animal in group 1 and one animal in group 3 developed large urinomas secondary to anastomotic failure. The animals that received fibrin glue over the anastomotic site (groups 2 and 4) all showed narrowed anastomoses with severe hydronephrosis. CONCLUSIONS: With available instrumentation, laparoscopic ureterocalicostomy is technically feasible. Nitinol clip technology significantly reduces collecting-system reconstruction time. Application of fibrin glue as a urinary tract sealant resulted in an unexpected adverse outcome.     

Safety and efficacy of ultrasonography as an adjunct to fluoroscopy for renal access in percutaneous nephrolithotomy (PCNL)

Study Type – Therapy (case series) Level of Evidence 4

OBJECTIVE

? To evaluate the safety and efficacy of ultrasonography (US)‐guided renal access in percutaneous nephrolithotomy (PCNL), as compared with conventional fluoroscopy‐guided renal access in a prospective randomized trial.

PATIENTS AND METHODS

? From January 2008 to October 2009, 224 patients with renal calculi undergoing PCNL were randomized into two groups. ? Group 1 (112 patients) underwent PCNL using only fluoroscopy‐guided renal access; while in group 2 (112 patients), US guidance for puncture was used in addition to fluoroscopy. ? The inclusion criteria were: normal renal functions, American Society of Anesthesiology scores 1 or 2, absence of congenital abnormalities, aged 15–70 years, and anticipated single‐tract procedure. The patients in both groups were matched for age, sex, and stone characteristics. ? The Student t‐test was used for statistical analysis with an allowable error of 5%.

RESULTS

? The mean time to successful puncture was 3.2 min and 1.8 min in group 1 and group 2, respectively (P < 0.01). ? The mean duration of radiation exposure to successful puncture was 28.6 s in group 1 and 14.4 s in group 2 (P < 0.01). ? The mean numbers of attempts for successful puncture in the desired calyx was 3.3 in group 1 as compared with 1.5 in group 2 (P < 0.01). ? The meantime taken for tract formation in group 1 was 7.4 min with radiation exposure of 82 s, while in group 2 it took 4.8 min with radiation exposure of 58 s (P < 0.01). ? Successful access was achieved in all patients. All patients were stone‐free at the end of the operation. The hospital stay (2–3 days) was same in both groups. There was no incidence of significant bleeding requiring transfusion during or after surgery. All the patients were followed‐up for a ≥6 months.

CONCLUSION

? US‐guided puncture in PCNL helps in increasing accuracy of puncture and decreasing radiation exposure for the surgical team and the patients.     

One-step percutaneous nephrostomy in patients with a history of open nephrolithotomy: comparison with the fascial dilator system

BACKGROUND AND PURPOSE: A percutaneous nephrostomy (PCN) done on the same side as a previous open nephrolithotomy is always technically challenging. A novel one-step PCN tube that allows the puncture and placement of a drainage tube to be done in a single step has been developed. The hydrophilic coating on the tube's surface significantly reduces friction and allows easier insertion. We evaluated the tube's efficiency and safety compared with the traditional fascial dilator system. PATIENTS AND METHODS: Sixty-five patients with a history of open nephrolithotomy were randomly allocated (with the aid of a computer-derived assignment number) into two groups to have PCN performed in one step or multiple steps. In the one-step group, a new type of PCN tube was used. In the multistep group, fascial dilators were used serially prior to tube insertion. The two groups were similar in terms of mean age, width of target calix, and baseline serum creatinine and hemoglobin concentrations. The operating times, intubation rates, and complications in the two groups were compared. RESULTS: The mean number of attempts required to access the collecting system was 1.1 +/- 0.6 in the one-step group v 2.3 +/- 1.2 in the multistep group (P = 0.002), the successful intubation rate was 96.9% v 78.8% (P = 0.012), the mean operating time was 10.2 +/- 2.4 minutes v 25.6 +/- 2.8 minutes (P = 0.029), and the rate of intraoperative and postoperative complications was 3.1% v 15.2%, respectively (P = 0.019). No major complications occurred in the one-step group. CONCLUSIONS: The one-step PCN tube is a convenient and efficacious method for accessing an anatomic region where open nephrolithotomy was done previously and is a simple method for nephrostomy tube placement.     

A study on comparative outcomes of percutaneous nephrolithotomy in prone, supine, and flank positions

Purpose

To compare percutaneous nephrolithotomy (PCNL) safety and efficacy in prone, supine, and flank positions.

Methods

A total number of 150 candidates for PCNL were randomly assigned into prone, supine, and flank groups. Patients in groups 1 and 2 underwent fluoroscopy-guided PCNL in prone and supine positions, respectively, while patients in group 3 underwent ultrasonography-guided PCNL in lateral position.

Results

The success rates were 92, 86, and 88 % in prone, supine, and flank positions, respectively (P = 0.7). The mean access duration was 6.9 ± 4.2, 11.1 ± 5.8, and 10.8 ± 4.1 min (P = 0.08), and the mean operation time was 68.7 ± 37.4, 54.2 ± 25.1 and 74.4 ± 26.9 min (P = 0.04) in prone, supine, and flank groups, respectively. Pyelocaliceal perforation occurred in 2 (4 %), 2 (4 %), and 3 (6 %) patients in prone, supine, and flank positions, respectively (P = 1).

Conclusion

We believe that PCNL in both supine and flank positions are as safe and relatively effective as prone position in experienced hands. Preference of the surgeon and proper case selection for each procedure is very important and necessary.     

One-stage tract dilation for percutaneous nephrolithotomy: is it justified?

PURPOSE: To assess the feasibility of one-stage acute dilation of the nephrostomy tract with a 30F Amplatz dilator in patients who are candidate for percutaneous nephrolithotomy (PCNL) regardless of whether there is a previous renal scar to make the procedure less time consuming and more cost effective. PATIENTS AND METHODS: The outcomes of one-stage tract dilation for PCNL in 100 consecutive patients with and without a history of ipsilateral open stone surgery (OSS), treated by one surgeon, were examined prospectively. Forty-six patients (group 1) had a history of ipsilateral OSS, and 54 patients (group 2) did not have this history. Demographic data as well as intraoperative information, such as access time and radiation exposure time during access, were recorded. The success of the access technique and its bleeding complications were analyzed between the two groups. RESULTS: By applying a "one-stage" technique, the targeted calix could be entered with a success rate of 93%. There was no difference in the procedural success rate between groups 1 and 2 (93.5% v 92.6%, respectively). All seven failed attempts (7%; three with previous OSS) were managed successfully using an Alken dilator to gain access to the proposed calix in the same session. Previous OSS did not impact access time, radiation exposure time during access, postoperative hemoglobin drop, and bleeding complications. There were no visceral and vascular injuries. CONCLUSIONS: One-stage tract dilation for PCNL is a safe and effective method in almost every adult patient.     

Percutaneous nephrolithotomy for complex caliceal calculi and staghorn stones in children less than 5 years of age

BACKGROUND AND PURPOSE: Treatment of children with staghorn and complex caliceal calculi is one of the most challenging problems in urology. We present our experience with percutaneous nephrolithotomy (PCNL) monotherapy for staghorn and complex caliceal calculi in children less than 5 years of age. PATIENTS AND METHODS: Between 1991 and 2004, 27 boys and 9 girls aged 11 months to 4.5 years underwent PCNL for staghorn (33%) or complex caliceal (67%) calculi. The average bulk of the stones was 140.17 +/- 42.16 mm(2) (range 61-253 mm(2)). Staging of the procedure was preferred in children with renal insufficiency, urinary-tract infection, fragmentation time >60 minutes, or a stone burden requiring more than two tracts. Essential steps of the technique were a dynamic contrast study to select the appropriate-size Amplatz sheath and ultrasound guidance for renal access. RESULTS: The average operative time was 72.11 +/- 28.86 minutes. The stone-free rate was 86%, the mean hemoglobin drop was 2.2 +/- 0.95 g/dL, and the mean hospital stay was 3.5 days. Less than half of the patients (42%) were treated in a single stage, the remainder requiring multiple procedures. Only 39% could be treated with a single tract. There was statistically significant increase in the blood loss in patients requiring multiple tracts (P = 0.008); however, staging the procedure did not increase the blood loss (P = 0.06). CONCLUSION: Percutaneous nephrolithotomy is safe and effective in children less than 5 years of age. Staging the procedure, instrument modification, the timed "multi mini-perc" technique, and ultrasound-guided access help in achieving maximum stone clearance with minimal morbidity.