Getting hot in here! Comparison of Holmium vs. thulium laser in an anatomic hydrogel kidney model

As laser technology has advanced, high-power lasers have become increasingly common. The Holmium: yttrium-aluminum-garnet (Ho:YAG) laser has long been accepted as the standard for laser lithotripsy. The thulium fiber laser (TFL) has recently been established as a viable option. The aim of this study is to evaluate thermal dose and temperature for the Ho:YAG laser to the TFL at four different laser settings while varying energy, frequency, operator duty cycle (ODC). Utilizing high-fidelity, 3D-printed hydrogel models of a pelvicalyceal collecting system (PCS) with a synthetic BegoStone implanted in the renal pelvis, laser lithotripsy was performed with the Ho:YAG laser or TFL. At a standard power (40W) and irrigation (17.9 ml/min), we evaluated four different laser settings with ODC variations with different time-on intervals. Temperature was measured at two separate locations. In general, the TFL yielded greater cumulative thermal doses than the Ho:YAG laser. Thermal dose and temperature were typically greater at the stone when compared away from the stone. Regarding the TFL, there was no general trend if fragmentation or dusting settings yielded greater thermal doses or temperatures. The TFL generated greater temperatures and thermal doses in general than the Ho:YAG laser with Moses technology. Temperatures and thermal doses were greater closer to the laser fiber tip. It is inconclusive as to whether fragmentation or dusting settings elicit greater thermal loads for the TFL. Energy, frequency, ODC, and laser-on time significantly impact thermal loads during ureteroscopic laser lithotripsy, independent of power.

WATTS happening? Evaluation of thermal dose during holmium laser lithotripsy in a high-fidelity anatomic model

PURPOSE

To evaluate the thermal profiles of the holmium laser at different laser parameters at different locations in an in vitro anatomic pelvicalyceal collecting system (PCS) model. Laser lithotripsy is the cornerstone of treatment for urolithiasis. With the prevalence of high-powered lasers, stone ablation efficiency has become more pronounced. Patient safety remains paramount during surgery. It is well recognized that the heat generated from laser lithotripsy has the potential to cause thermal tissue damage.

METHODS

Utilizing high-fidelity, 3D printed hydrogel models of a PCS with a synthetic BegoStone implanted in the renal pelvis, laser lithotripsy was performed with the Moses 2.0 holmium laser. At a standard power (40 W) and irrigation pressure (100 cm H2O), we evaluated operator duty cycle (ODC) variations with different time-on intervals at four different laser settings. Temperature was measured at two separate locations-at the stone and away from the stone.

RESULTS

Temperatures were highest closest to the laser tip with a decrease away from the laser. Fluid temperatures increased with longer laser-on times and higher ODCs. Thermal doses were greater with increased ODCs and the threshold for thermal injury was reached for ODCs of 75% and 100%.

CONCLUSION

Temperature generation and thermal dose delivered are greatest closer to the tip of the laser fiber and are not dependent on power alone. Significant temperature differences were noted between four laser settings at a standardized power (40 W). Temperatures can be influenced by a variety of factors, such as laser-on time, operator duty cycle, and location in the PCS.

Turning up the HEAT: Surgical simulation of the Moses 2.0 laser in an anatomic model

INTRODUCTION

With advancements in laser technology, urologists have been able to treat urinary calculi more efficiently by increasing the energy delivered to the stone. With increases in power used, there is an increase in temperatures generated during laser lithotripsy. The aim of this study was to evaluate the thermal dose and temperatures generated with four laser settings at a standardized power in a high-fidelity, anatomic model.

METHODS

Using high-fidelity, 3D printed hydrogel models of a pelvicalyceal collecting system with a synthetic BegoStone implanted in the renal pelvis, surgical simulation of ureteroscopic laser lithotripsy was performed with the Moses 2.0 holmium laser. At a standard power (40 W) and irrigation pressure (100 cm H2O), we evaluated operator duty cycle (ODC) variations with different time-on intervals at four different laser settings. Temperature was measured at two separate locations: at the stone and ureteropelvic junction.

RESULTS

Greater cumulative thermal doses and maximal temperatures were achieved with greater ODCs and longer laser activation periods. There were statistically significant differences between the thermal doses and temperature profiles of the laser settings evaluated. Temperatures were greater closer to the tip of the laser fiber.

CONCLUSIONS

Laser energy and frequency play an important role in the thermal loads delivered during laser lithotripsy. Urologists must perform laser lithotripsy cautiously when aggressively treating large renal pelvis stones, as dangerous temperatures can be reached. To reduce the risk of causing thermal tissue injury, urologists should consider reducing their ODC and laser-on time.

From Consensus to Validation: A Multicenter Study for Design and Development of a Holmium Laser Enucleation of the Prostate Hydrogel Simulation Platform

Background: Holmium laser enucleation of the prostate (HoLEP) has emerged as a new gold standard for treatment of benign prostatic hyperplasia; however, its steep learning curve hinders generalization of this technique. Therefore, there is a need for a benchtop HoLEP simulator to reduce this learning curve and provide training. We have developed a nonbiohazardous HoLEP simulator using modern education theory and validated it in a multicenter study. Materials and Methods: Six experts established key components for a HoLEP simulator through a Delphi consensus over three rounds including 250 questions. After consensus, a digital design was created and approved by experts, then used to fabricate a physical prototype using three-dimensional printing and hydrogel molding. After a process of iterative prototype testing, experts completed a survey assessing the simulator with a 5-point Likert scale for final approval. The approved model was validated with 56 expert and novice participants at seven institutions using subjective and objective performance metrics. Results: Consensus was reached on 85 of 250 questions, and experts found the physical model to adequately replicate 82.5% of required features. Objective metrics were statistically significant (p < 0.0001) when comparing experts and novices for enucleation time (37.4 ± 8.2 vs 16.7 ± 6.8 minutes), adenoma weight (79.6 ± 20.4 vs 36.2 ± 9.9 g), and complications (6 vs 22), respectively. Conclusion: We have effectively completed a multicenter study to develop and validate a nonbiohazardous benchtop simulator for HoLEP through modern education theory. A training curriculum including this simulator is currently under development.

Neighborhood Social Vulnerability Impacts Quality of Life in Kidney Stone Patients

INTRODUCTION

This study aimed to investigate the association between social vulnerability, as measured by the Centers for Disease Control and Prevention's Social Vulnerability Index (SVI), and the quality of life (QoL) of kidney stone patients using the validated Wisconsin Stone Quality of Life Questionnaire (WISQOL).

METHODS

A retrospective analysis was conducted on medical records of new urolithiasis patients who completed the WISQOL at the University of Rochester Medical Center kidney stone clinic. The primary outcome was WISQOL score, which was measured across multiple domains. SVI was used to assess social vulnerability. Neighborhoods with high SVI were defined by a threshold greater than or equal to the 75th percentile nationally. Demographic and clinical data were collected. Statistical analyses, including univariate tests and multivariate linear regression, were performed to evaluate the relationships between social vulnerability and disease-specific QoL.

RESULTS

A total of 1718 patients were included in the study. One hundred five subjects (6.1%) were from neighborhoods of high social vulnerability. Patients residing in neighborhoods with high social vulnerability (SVI quartile) reported significantly lower QoL scores (69.1 vs 77.2; P = .001) and this persisted across all domains, including social impact (32.6 vs 35.1; P = .002), emotional impact (25.2 vs 27.5; P = .006), disease impact (28.5 vs 31.4; P = .001), and vitality (10.3 vs 11.2; P = .015). Younger age, female sex, and higher number of comorbidities were identified as independent predictors of lower QoL scores. However, non-White race and Latinx ethnicity did not exhibit a significant association with QoL scores.

CONCLUSIONS

These findings highlight the negative impact of high social vulnerability on QoL, emphasizing the importance of considering socioeconomic factors in patient care. These results emphasize the need for targeted interventions to support vulnerable populations. While this study offers initial insights, further research is essential to corroborate these outcomes across larger and more diverse populations.

Evaluation of Mixed Reality Technologies for Remote Feedback and Guidance During Transrectal Ultrasound Biopsy Simulation: A Prospective, Randomized, Crossover Study

OBJECTIVE

To compare equivalency of remote to in-person training during simulated transrectal ultrasound-guided prostate biopsy, we combined three technologies (mixed reality [MR] software, smart glasses, and hydrogel simulation model). Taken together, telemonitoring harnesses data streaming to provide real-time supervision and technical assistance for surgical procedures from an expert at a remote geographical location.

METHODS

Nineteen students were randomized into two groups (MR-first and in-person-first) and proctored to measure prostate volume and perform 14-biopsies over seven sessions: pretest, two MR/in-person-guided training sessions, mid-test, crossover into two in-person/MR-guided training sessions, and post-test. MR sessions utilized Vuzix smart glasses with MR software (HelpLightning) to share the student's first-person perspective and Zoom to project the ultrasound screen to a remote instructor. Training and test sessions utilized single-color and seven-color prostate models, respectively. Accuracy of biopsy cores from test sessions were compared. Perception of instruction following each training session using 5-point Likert scales across five domains was assessed. Preference of instruction modality was assessed qualitatively.

RESULTS

Comparison of mid-test performance following two training sessions was similar across the two groups (MR-first 63.8% vs in-person-first 57.6%, P = .340). Following crossover, difference in post-test performance of the MR-first group and the in-person-first group approached significance (MR-first 80.2% vs in-person-first 70.8%, P = .050). Student evaluation of MR and in-person instruction following training sessions was similar across the five metrics.

CONCLUSION

MR-based remote learning is equally effective when compared to traditional in-person instruction.

Recent Advances in Surgical Simulation For Resident Education

PURPOSE OF REVIEW

Surgical simulation has become a cornerstone for the training of surgical residents, especially for urology residents. Urology as a specialty bolsters a diverse range of procedures requiring a variety of technical skills ranging from open and robotic surgery to endoscopic procedures. While hands-on supervised training on patients still remains the foundation of residency training and education, it may not be sufficient to achieve proficiency for graduation even if case minimums are achieved. It has been well-established that simulation-based education (SBE) can supplement residency training and achieve the required proficiency benchmarks.

RECENT FINDINGS

Low-fidelity modules, such as benchtop suture kits or laparoscopic boxes, can establish a strong basic skills foundation. Eventually, residents progress to high-fidelity models to refine application of technical skills and improve operative performance. Human cadavers and animal models remain the gold standard for procedural SBE. Recently, given the well-recognized financial and ethical costs associated with cadaveric and animal models, residency programs have shifted their investments toward virtual and more immersive simulations. Urology as a field has pushed the boundaries of SBE and has reached a level where unexplored modalities, e.g., 3D printing, augmented reality, and polymer casting, are widely utilized for surgical training as well as preparation for challenging cases at both the residents, attending and team training level.

Predicting Surgical Experience After Robotic Nerve-sparing Radical Prostatectomy Simulation Using a Machine Learning-based Multimodal Analysis of Objective Performance Metrics

INTRODUCTION

Machine learning methods have emerged as objective tools to evaluate operative performance in urological procedures. Our objectives were to establish machine learning-based methods for predicting surgeon caseload for nerve-sparing robot-assisted radical prostatectomy using our validated hydrogel-based simulation platform and identify potential metrics of surgical expertise.

METHODS

Video, robotic kinematics, and force sensor data were collected from 35 board-certified urologists at the 2022 AUA conference. Video was annotated for surgical gestures. Objective performance indicators were derived from robotic system kinematic data. Force metrics were calculated from hydrogel model integrated sensors. Data were fitted to 3 supervised machine learning models-logistic regression, support vector machine, and k-nearest neighbors-which were used to predict procedure-specific learning curve proficiency. Recursive feature elimination was used to optimize the best performing model.

RESULTS

Logistic regression predicted caseload with the highest AUC score for 5/7 possible data combinations (force, 64%; objective performance indicators + gestures, 94%; objective performance indicators + force, 90%; gestures + force, 93%; objective performance indicators + gestures + force, 94%). Support vector machine predicted the highest AUC score for objective performance indicators (82%) and gestures (94%). Logistic regression with recursive feature elimination was the most effective model reaching 96% AUC in predicting case-specific experience. Most contributory features were identified across all model types.

CONCLUSIONS

We have created a machine learning-based algorithm utilizing a novel combination of objective performance indicators, gesture analysis, and integrated force metrics to predict surgical experience, capable of discriminating between surgeons with low or high robot-assisted radical prostatectomy caseload with 96% AUC in a standardized, simulation-based environment.

Three-dimensional printed hydrogel model vs cadaver: comparing inflatable penile prosthesis training and evaluation

BACKGROUND

Penile prosthesis implantation offers a durable, safe, and effective treatment option for male erectile dysfunction; however, many urologists feel apprehensive and uncomfortable placing penile prostheses due to limited training, low surgical experience, and intra- and postoperative complication management.

AIM

To compare a previously validated hydrogel inflatable penile prosthesis (IPP) training model with cadaver simulations across 4 main categories: anatomic replication and realism, procedural replication and realism, educational effectiveness, and efficacy and safety.

METHODS

An overall 88 participants (15 attendings, 18 fellows, and 55 residents) performed guided IPP placements on a cadaver and a hydrogel model. Based on a 5-point Likert scale, postsurveys were used to assess the participants' opinions regarding anatomic replication and realism, procedural replication and realism, educational effectiveness, and safety between the hydrogel model and cadavers.

OUTCOMES

A direct head-to-head scenario was created, allowing participants to fully utilize the hydrogel model and cadaver, which ensured the most accurate comparison possible.

RESULTS

A total of 84% agreed that the hydrogel model replicates the relevant human cadaveric anatomy for the procedure, whereas 69% agreed that the hydrogel tissue resembles the appearance of cadaveric tissue. Regarding the pubic bone, outer skin, corporal bodies, dartos layer, and scrotum, 79%, 74%, 82%, 46%, and 30% respectively agreed that the hydrogel tissue resembled the texture/behavior of cadavers. Furthermore, 66% of participants agreed that the hydrogel model replicates all the procedural steps. Specifically, participants agreed that the model replicates the skin incision/dartos dissection (74%), placement of stay suture and corporotomy (92%), corporal dilation (81%), measurement of prosthetic size (98%), reservoir placement (43%), IPP placement (91%), scrotal pump placement (48%), and skin closure (51%). Finally, 86%, 93%, and 78% agreed that the hydrogel model is useful for improving technical skills, as a teaching/practicing tool, and as an evaluation tool, respectively. To conclude, 81% of participants stated that they would include the hydrogel model platform in their current training.

CLINICAL IMPLICATIONS

By replicating the IPP procedure, the hydrogel model offers an additional high-fidelity training opportunity for urologists, allowing them to improve their skills and confidence in placing penile prostheses, with the goal of improving patient surgical outcomes.

STRENGTHS AND LIMITATIONS

The hydrogel training model allows users to perform the entire IPP placement procedure with high anatomic realism and educational effectiveness, maintaining many of the high-fidelity benefits seen in cadavers while improving safety and accessibility.

CONCLUSION

Ultimately, this high-fidelity nonbiohazardous training model can be used to supplement and bolster current IPP training curriculums.

Do Skills Naturally Transfer Between Multiport and Single-Port Robotic Platforms? A Comparative Study in a Simulated Environment

Introduction and Objective: With introduction of the da Vinci single-port (SP) system, we evaluated which multiport (MP) robotic skills are naturally transferable to the SP platform. Methods: Three groups of urologists: Group 1 (5 inexperienced in MP and SP), Group 2 (5 experienced in MP without SP experience), and Group 3 (2 experienced in both MP and SP) were recruited to complete a validated urethrovesical anastomosis simulation using MP followed by SP robots. Performance was graded using both GEARS and RACE scales. Subjective cognitive load measurements (Surg-TLX and difficulty ratings [/20] of instrument collisions camera and EndoWrist movement) were collected. Results: GEARS and RACE scores for Groups 1 and 3 were maintained on switching from MP to SP (Group 3 scored significantly higher on both systems). Surg-TLX and difficulty scores were also maintained for both groups on switching from MP and SP except for a significant increase in SP camera movement (+7.2, p = 0.03) in Group 1 compared to Group 3 that maintained low scores on both. Group 2 demonstrated significant lower GEARS (-2.9, p = 0.047) and RACE (-5.1, p = 0.011) scores on SP vs MP. On subanalysis, GEARS subscores for force sensitivity and robotic control (-0.7, p = 0.04; -0.9, p = 0.02) and RACE subscores for needle entry, needle driving, and tissue approximation (-0.9, p = 0.01; -1.0, p = 0.02; -1.0, p < 0.01) significantly decreased. GEARS (depth perception, bimanual dexterity, and efficiency) and RACE subscores (needle positioning and suture placement) were maintained. All participants scored significantly lower in knot tying on the SP robot (-1.0, p = 0.03; -1.2, p = 0.02, respectively). Group 2 reported higher Surg-TLX (+13 pts, p = 0.015) and difficulty ratings on SP vs MP (+11.8, p < 0.01; +13.6, p < 0.01; +14 pts, p < 0.01). Conclusions: The partial skill transference across robots raises the question regarding SP-specific training for urologists proficient in MP. Novices maintained difficulty scores and cognitive load across platforms, suggesting that concurrent SP and MP training may be preferred.

Robotic Assisted Transplant Nephrectomy: Case Series and Training Model for Improving Adoption

Introduction

Open transplant nephrectomy for failed renal allograft is an invasive procedure associated with significant perioperative morbidity and mortality. Minimally invasive surgical approaches have improved a variety of patient outcomes for many surgeries. Thus, robotic assisted transplant nephrectomy (RATN) potentially offers significant patient benefit. Although previously reported, there remains a paucity of data on RATN outcomes and techniques.

Methods

Four perfused, high-fidelity hydrogel models were created using previously described techniques and used for simulated RATN. Subsequently performed institutional cases were included for analysis. Intra- and postoperative variables along with patient demographics were retrospectively obtained through parsing of patient records.

Results

Simulated nephrectomy time was 67.33 minutes (35.75 - 98.91). Five patients underwent RATN. There were four male and one female patients. The average age was 47 years. The most common indication was abdominal pain secondary to rejection (3/5). Mean blood loss was 188 mL; mean operative time was 243 minutes, and mean length of stay was 4.5 days. Intraoperatively there were two incidences of small cystotomies. One patient was readmitted within 30 days for intraabdominal abscess.

Conclusion

This study adds to the growing literature around RATN, demonstrating the feasibility of the technique and reporting good outcomes for this cohort.

Utilizing head-mounted eye trackers to analyze patterns and decision-making strategies of 3D virtual modelling platform (IRIS™) during preoperative planning for renal cancer surgeries

PURPOSE

IRIS^™ provides interactive, 3D anatomical visualizations of renal anatomy for pre-operative planning that can be manipulated by altering transparency, rotating, zooming, panning, and overlaying the CT scan. Our objective was to analyze how eye tracking metrics and utilization patterns differ between preoperative surgical planning of renal masses using IRIS and CT scans.

METHODS

Seven surgeons randomly reviewed IRIS and CT images of 9 patients with renal masses [5 high complexity (RENAL score ≥ 8), 4 low complexity (≤ 7)]. Surgeons answered a series of questions regarding patient anatomy, perceived difficulty (/100), confidence (/100), and surgical plan. Eye tracking metrics (mean pupil diameter, number of fixations, and gaze duration) were collected.

RESULTS

Surgeons spent significantly less time interpreting data from IRIS than CT scans (- 67.1 s, p < 0.01) and had higher inter-rater agreement of surgical approach after viewing IRIS (α = 0.16-0.34). After viewing IRIS, surgical plans although not statistically significant demonstrated a greater tendency towards a more selective ischemia approaches which positively correlated with improved identification of vascular anatomy. Planned surgical approach changed in 22/59 of the cases. Compared to viewing the CT scan, left and right mean pupil diameter and number/duration of fixations were significantly lower when using IRIS (p < 0.01, p < 0.01, p = 0.42, p < 0.01, respectively), indicating interpreting information from IRIS required less mental effort despite under-utilizing its interactive features.

CONCLUSIONS

Surgeons extrapolated more detailed information in less time with less mental effort using IRIS than CT scans and proposed surgical approaches with potential to enhanced surgical outcomes.

Comparison of Multi-Parametric MRI of the Prostate to 3D Prostate Computer Aided Designs and 3D-Printed Prostate Models for Pre-Operative Planning of Radical Prostatectomies: A Pilot Study

OBJECTIVE

To evaluate the use of 3D computed aided designs and 3D-printed models as pre-operative planning tools for urologists, in addition to radiologist interpreted mp-MRIS, prior to radical prostatectomy procedures.

METHODS

Ten patients with biopsy-positive lesions detected on mp-MRI were retrospectively selected. Radiologists identified lesion locations using a Prostate Imaging-Reporting and Data System (PI-RADS) map and segmented the prostate, lesion(s), and surrounding anatomy to create 3D-CADs and 3D-printed models for each patient. 6 uro-oncologists randomly reviewed three modalities (mp-MRI, 3D-CAD, and 3D-printed models) for each patient and identified lesion locations which were graded for accuracy against the radiologists' answers. Questionnaires assessed decision confidence, ease-of-interpretation, and usefulness for preoperative planning for each modality.

RESULTS

Using 3D-CADs and 3D-printed models compared to mp-MRI, urologists were 2.4x and 2.8x more accurate at identifying the lesion(s), 2.7x and 3.2x faster, 1.6x and 1.63x more confident, and reported it was 1.6x and 1.7x easier to interpret. 3D-CADs and 3D-printed models were reported significantly more useful for overall pre-operative planning, identifying lesion location(s), determining degree of nerve sparing, obtaining negative margins, and patient counseling. Sub-analysis showed 3D-printed models demonstrated significant improvements in ease-of-interpretation, speed, usefulness for obtaining negative margins, and patient counseling compared to 3D-CADs.

CONCLUSION

3D-CADs and 3D-printed models are useful adjuncts to mp-MRI in providing urologists with more practical, accurate, and efficient pre-operative planning.