The Influence of Super-Mini Percutaneous Nephrolithotomy on Renal Pelvic Pressure In Vivo

Assessment of Effectiveness and Safety of Aspiration-Assisted Nephrostomic Access Sheaths in PCNL and Intrarenal Pressures Evaluation: A Systematic Review of the Literature

Background: Different suction-assisted nephrostomic sheaths have been developed for percutaneous nephrolithotomy (PCNL). Objectives: (1) To examine PCNL techniques performed with different aspiration-assisted sheaths (Clear Petra® sheath, Superperc, SuperminiPCNL, and a miniPCNL patented sheath), with specific regard to effectiveness and safety outcomes in adult and paediatric patients; (2) to extrapolate intrarenal pressure (IRP) data during these procedures. Methods: A systematic literature search was performed in accordance with PRISMA guidelines. Relevant articles up to 8 February 2024 were included. Results: Twenty-five studies were selected, thirteen retrospective and twelve prospective. The use of four different aspirating sheaths for miniPCNL was reported: Clear Petra® sheath, Superperc, SuperminiPCNL, and a miniPCNL patented sheath. Stone free rates (SFRs) across techniques ranged from 71.3% to 100%, and complication rates from 1.5% to 38.9%. Infectious complication rates varied from 0 to 27.8% and bleeding complication rates from 0 to 8.9%. Most complications were low grade ones. The trend among studies comparing aspiration- and non-aspiration-assisted miniPCNL was towards equivalent or better SFRs and lower overall infectious and bleeding complication rates in suction techniques. Operation time was consistently lower in suction procedures, with a mean shortening of the procedural time of 19 min. Seven studies reported IRP values during suction miniPCNL. Two studies reported satisfactory SFRs and adequate safety profiles in paediatric patient cohorts. Conclusions: MiniPCNL with aspirating sheaths appears to be safe and effective in both adult and paediatric patients. A trend towards a reduction of overall infectious and bleeding complications with respect to non-suction procedures is evident, with comparable or better SFRs and consistently shorter operative times. The IRP profile seems to be safe with the aid of aspirating sheaths. However, high quality evidence on this topic is still lacking.

Risk factors of high fluid absorption in patients treated with mini-PCNL: a single-center prospective study

BACKGROUND

The factors influencing fluid absorption in mini-percutaneous nephrolithotripsy (mini-PCNL) are still unknown. We aim to investigate the factors that influence irrigation fluid absorption during mini-PCNL.

METHODS

A total of 94 patients who underwent mini-PCNL were included in this prospective study. The endoscopic surgical monitoring system (ESMS) was used to measure the volume of irrigation fluid absorbed during the procedure. Irrigating time, the total volume of irrigation fluid, stone size, S.T.O.N.E. score, hemoglobin, electrolyte levels, and postoperative complications were recorded.

RESULTS

A significant correlation was observed between fluid absorption and the presence of postoperative fever, and based on this phenomenon, patients were divided into low and high fluid absorption groups. The serum creatinine level in the high fluid absorption group was significantly high (7 vs. 16.5, p = 0.02). Significant differences were observed between the low and high fluid absorption groups in terms of mean stone size (21.70 mm vs. 26.78 mm), presence of stone burden ≥ 800 mm2 (4% vs. 23%), S.T.O.N.E. score > 8 (4% vs. 38%), the fluid used > 18,596 ml (19% vs. 78%), irrigation time (55.61 min vs. 91.28 min), and perfusion rate (24% vs. 45%) (all p < 0.05). The rates of postoperative fever and SIRS in the high fluid absorption group were significantly high (p < 0.05).

CONCLUSIONS

Mean stone size, presence of stone burden ≥ 800 mm2, S.T.O.N.E. score > 8, the fluid used > 18596 mL, irrigation time, and perfusion rate are risk factors of intraoperative fluid absorption in mini-PCNL.

Suction in Percutaneous Nephrolithotripsy: Evolution, Development, and Outcomes from Experimental and Clinical studies. Results from a Systematic Review

CONTEXT

Controversy exists regarding the therapeutic benefit of suction use during percutaneous nephrolithotripsy (PCNL).

OBJECTIVE

To review and highlight the options available in the use of suction for PCNL, and to discuss their strengths and limitations.

EVIDENCE ACQUISITION

A systematic literature search was performed using Scopus, EMBASE, and PubMed. Thirty four studies were included. There was one ex vivo study. Among clinical studies, 24 used a vacuum/suctioning sheath and nine a handpiece suction device/direct-in-scope suction. The suction technique was employed in standard, mini-PCNL, supermini-PCNL, and enhanced supermini‑PCNL techniques.

EVIDENCE SYNTHESIS

Handpiece suction devices demonstrated better safety and efficiency in treating large stones than nonsuction PCNL and in a much shorter time. Trilogy and ShockPulse-SE were equally effective, safe, and versatile for standard PCNL and mini-PCNL. The heavier handpiece makes Trilogy less ergonomically friendly. Laser suction handpiece devices can potentiate laser lithotripsy by allowing for better laser control with simultaneous suction of small fragments and dust. Integrated suction-based sheaths are available in reusable and disposable forms for mini-PCNL only. Mini-PCNL with suction reported superior outcomes for operative time and stone-free rate to mini-PCNL. This also helped minimize infectious complications by a combination of intrarenal pressure reduction and faster aspiration of irrigation fluid reducing the risk of sepsis, enhance intraoperative vision, and improve lithotripsy efficiency, which makes it a very attractive evolution for PCNL.

CONCLUSIONS

Suction devices in PCNL are reforming the way PCNL is being done. Adding suction to mini-PCNL reduces infectious complications and improves the stone-free rate. Our review shows that despite the limited evidence, suction techniques appear to improve PCNL outcomes.

PATIENT SUMMARY

In this review, we looked at the intra- and perioperative outcomes of percutaneous nephrolithotripsy (PCNL) with the addition of suction. With better stone fragmentation and fewer postoperative infections, this technology is very useful particularly for mini-PCNL.

A randomized controlled trial comparing infectious complications using mini perc with and without suction for renal stones less than 3 cm in size

The purpose was to do a study to compare infectious complications in patients operated for MiniPerc or Minimally invasive Percutaneous Nephrolithotomy (MPCNL) using MIP and MPCNL with suction using Shah Superperc sheath for medium-sized renal stones less than 3 cm in size. The primary objective of this study is to compare the infectious complications and the secondary objectives are to compare stone-free rates, complication rates and operative times. A prospective randomized controlled trial with patients having proximal ureteral and renal stones of 10-30 mm size and planned for MPCNL done at a single institute. A total of 80 consecutively admitted patients with written informed consent were included for randomization with 40 patients in each arm of MPCNL and suction MPCNL. The median age in MPCNL and suction MPCNL arms were 48 and 49 years, the median stone size of 15.45 and 16.7 cm, the Median stone volume of 1576.2 vs 1752 mm3, and the median stone density of 1258 and 1250 Hu, the median hospital stay of 3 days in both arms were comparable. Infectious complications were comparable in both arms. Operative time was significantly less in the suction MPCNL group (26.5 min-IQR 17-34.8) than in the MPCNL group (34.8 min-IQR 20-45), p = 0.021 and stone-free rates (SFR), were more in Suction MPCNL arm 97.5% than in MPCNL 87.5%, p = 0.04. Overall, the complication rates were comparable in both arms. Suction MPCNL procedure resulted in shorter operating times and more SFR than conventional MPCNL with comparable complication rates.

Upper urinary tract pressures in endourology: a systematic review of range, variables and implications

OBJECTIVES

To systematically review the literature to ascertain the upper tract pressures generated during endourology, the relevant influencing variables and clinical implications.

MATERIALS AND METHODS

A systematic review of the MEDLINE, Scopus and Cochrane databases was performed by two authors independently (S.C., N.D.). Studies reporting ureteric or intrarenal pressures (IRP) during semi-rigid ureteroscopy (URS)/flexible ureterorenoscopy (fURS)/percutaneous nephrolithotomy (PCNL)/miniaturized PCNL (mPCNL) in the period 1950-2021 were identified. Both in vitro and in vivo studies were considered for inclusion. Findings were independently screened for eligibility based on content, with disagreements resolved by author consensus. Data were assessed for bias and compiled based on predefined variables.

RESULTS

Fifty-two studies met the inclusion criteria. Mean IRP appeared to frequently exceed a previously proposed threshold of 40 cmH₂ O. Semi-rigid URS with low-pressure irrigation (gravity <1 m) resulted in a wide mean IRP range (lowest reported 6.9 cmH₂ O, highest mean 149.5 ± 6.2 cmH₂ O; animal models). The lowest mean observed with fURS without a ureteric access sheath (UAS) was 47.6 ± 4.1 cmH₂ O, with the maximum peak IRP being 557.4 cmH₂ O (in vivo human data). UAS placement significantly reduced IRP during fURS, but did not guarantee pressure control with hand-operated pump/syringe irrigation. Miniaturization of PCNL sheaths was associated with increased IRP; however, a wide mean human IRP range has been recorded with both mPCNL (lowest -6.8 ± 2.2 cmH₂ O [suction sheath]; highest 41.2 ± 5.3 cmH₂ O) and standard PCNL (lowest 6.5 cmH₂ O; highest 41.2 cmH₂ O). Use of continuous suction in mPCNL results in greater control of mean IRP, although short pressure peaks >40 cmH₂ O are not entirely prevented. Definitive conclusions are limited by heterogeneity in study design and results. Postoperative pain and pyrexia may be correlated with increased IRP, however, few in vivo studies correlate clinical outcome with measured IRP.

CONCLUSIONS

Intrarenal pressure generated during upper tract endoscopy often exceeds 40 cmH₂ O. IRP is multifactorial in origin, with contributory variables discussed. Larger prospective human in vivo studies are required to further our understanding of IRP thresholds and clinical sequelae.

Current evidence for suction in endourological procedures: comprehensive review of literature

PURPOSE OF REVIEW

To identify the latest advances on the utilization of suctioning devices in the surgical treatment of urinary stones.

RECENT FINDINGS

Advances are being made to incorporate suction and pressure control capabilities in percutaneous and ureteroscopic lithotripsy. Multiple retrospective studies and few prospective studies have shown that suctioning with minimally invasive percutaneous nephrolithotomy, commonly referred to as Super MiniPerc, can lead to better stone-free rates (SFR) and shorter operative time with lower incidence of infectious complications. Suctioning during retrograde intrarenal surgery (RIRS) has mainly been achieved through suctioning ureteral access sheath. Here as well, the incorporation of suction improved the SFR, but most importantly, reduced the risk of postoperative infectious complications.

SUMMARY

Theoretically suction in endourological procedures could facilitate stone debris removal and could reduce intrarenal pressure at the same time allowing for increased irrigation flow potentially decreasing operation time and infectious complications. These claims are supported in contemporary clinical studies, reporting superior SFR and reduced postoperative infectious complications in both percutaneous nephrolithotomy and RIRS.

Surgical Parameters Related to Excessive Intrarenal Pressure during Minimally Invasive Percutaneous Nephrolithotomy in the Supine Position: A Prospective Observational Clinical Study

Objective

Excessive intrarenal pressure (IRP) during surgery for renal stones is related to postoperative complications due to systemic absorption of bacteria and endotoxins. This study is aimed at evaluating factors that induce excessive IRP in minimally invasive percutaneous lithotripsy (mini-PCNL) in the supine position.

Methods

27 patients underwent mini-PCNL for intrarenal stones under supine position and were analyzed in this study. The IRP changes were measured at the phases of “baseline,” “table tilting,” “upper-pole navigation,” “stone fragmentation,” and “vacuum cleaning effect.” The relationship between the mean IRP and cumulative time of IRP ≥ 30 cmH₂O was analyzed by according to the surgical parameters. Multiple regression analysis showed the effect of the surgical parameters on postoperative fever-related IRP elevation.

Results

Mean age was 59.3 ± 14.6 years. The mean stone burden was 24.6 ± 8.1 mm³. IRP was higher than baseline (31.6 ± 12.1) during upper-pole navigation (60.0 ± 22.9, p = 0.003) and stone fragmentation (46.2 ± 9.9, p < 0.001). The subgroup's IRP baseline < 20 cmH₂O significantly increased during the upper-pole navigation. Changes in IRP at each stage were affected by baseline IRP (p < 0.001), operation methods (p = 0.021), number of calyces with stones (p = 0.034), and laser energy of Joules (p = 0.041) and frequency (p = 0.038).

Conclusion

In supine mini-PCNL, the IRP was higher during laser fragmentation and upper-pole navigation. The table tilting procedure can be helpful in selected patients. The vacuum cleaner effect did not affect IRP.

Intrarenal pressures during percutaneous nephrolithotomy: a porcine kidney model

BACKGROUND

Increased intrarenal pressure during endoscopic lithotripsy is associated with increased adverse outcomes. The objective of this study was to evaluate the effect of various devices on IRP during percutaneous intrarenal surgery in ex vivo porcine kidney models.

METHODS

Whole intact porcine urinary tracts were harvested. Intrarenal pressure was measured using cystometrometry software. Intrarenal pressure during PCNL was recorded using variations of percutaneous access sheath size, irrigation height of 100 cm and 60 cm, use of a ureteric catheter and use of suction. The primary outcome was absolute IRP measurements. Secondary outcomes were comparisons of IRP between techniques.

RESULTS

Using a 30 Fr vs 26 Fr access sheath and 26 Fr nephroscope the mean pressure at an irrigation height of 60 cm was significantly lower than 100 cm (p = 0.0013 vs p < 0.0001, respectively). Pressure's during mini-PCNL were significantly higher than conventional PCNL in all variations. Using the 16.5 Fr access sheath and 12 Fr nephroscope produced a significantly lower pressure at a 60 cm irrigation height than 100 cm (p = 0.0010). IRP was significantly lower with a ureteric catheter in place vs no ureteric catheter at 100 cm (p = 0.0015) and at 60 cm (p = 0.0040).

CONCLUSIONS

Using standard PCNL tract sizes intrarenal pressure varied significantly depending on the height of the irrigation fluid. Mini-PCNL is at higher risk of pathological pressure, however, the use of a ureteric catheter significantly decreased pressure. To maintain safe IRP during PCNL urologists should be aware of these significant variations.

Super-mini percutaneous nephrolithotomy (SMP) vs retrograde intrarenal surgery (RIRS) in the management of renal calculi ≤ 2 cm: a propensity matched study

Objective

To compare the effectiveness and safety of Super-Mini PCNL (SMP) and Retrograde Intrarenal Surgery (RIRS) in the management of renal calculi ≤ 2 cm.

Patients and methods

A prospective, inter-institutional, observational study of patients presenting with renal calculi ≤ 2 cm. Patients underwent either SMP (Group 1) or RIRS (Group 2) and were performed by 2 experienced high-volume surgeons.

Results

Between September 2018 and April 2019, 593 patients underwent PCNL and 239 patients had RIRS in two tertiary centers. Among them, 149 patients were included for the final analysis after propensity-score matching out of which 75 patients underwent SMP in one center and 74 patients underwent RIRS in the other. The stone-free rate (SFR) was statistically significantly higher in Group 1 on POD-1 (98.66% vs. 89.19%; p = 0.015), and was still higher in Group 1 on POD-30 (98.66% vs. 93.24%, p = 0.092) SFR on both POD-1 and POD-30 for lower pole calculi was higher in Group 1 (100 vs. 82.61%, p = 0.047 and 100 vs 92.61% p = 0.171). The mean (SD) operative time was significantly shorter in Group 1 at 36.43 min (14.07) vs 51.15 (17.95) mins (p < 0.0001). The mean hemoglobin drop was significantly less in Group 1 (0.31 vs 0.53 gm%; p = 0.020). There were more Clavien–Dindo complications in Group 2 (p = 0.021). The mean VAS pain score was significantly less in Group 2 at 6 and 12 h postoperatively (2.52 vs 3.67, 1.85 vs 2.40, respectively: p < 0.0001), whereas the mean VAS pain score was significantly less in Group 1 at 24 h postoperatively (0.31 vs 1.01, p < 0.0001). The mean hospital stay was significantly shorter in Group 1 (28.37 vs 45.70 h; p < 0.0001).

Conclusion

SMP has significantly lower operative times, complication rates, shorter hospital stay, with higher stone-free rates compared to RIRS. SMP is associated with more early post-operative pain though.

Role of Intrarenal Pressure in Modern Day Endourology (Mini-PCNL and Flexible URS): a Systematic Review of Literature

PURPOSE OF REVIEW

To review the latest evidence about intrarenal pressures (IRPs) generated during flexible ureteroscopy (fURS) and mini percutaneous nephrolithotomy (mPCNL) and present tools and techniques to maintain decreased values.

RECENT FINDING

fURS and PCNL constitute the primary means of stone treatment. New flexible ureterorenoscopes with small diameter and miniaturized PCNL instruments achieve optimal stone-free rates (SFRs) while decreasing invasiveness and morbidity. Nevertheless, endourologists must remain cognizant regarding the dangers of increased IRPs to avoid complications. Current research presents essential information for urologists regarding this topic. During fURS, using a ureteral access sheath (UAS), we avoid extremely high IRPs with all irrigation types. During mPCNL, pressure remains low, mainly using the purging effect or a vacuum-assisted sheath. Devices of intraoperative IRP measurement and intelligent pressure control have proven their feasibility, accuracy and efficacy. These will have an increasing role to play in the future management of stone disease.

Pooled-analysis of efficacy and safety of minimally invasive versus standard percutaneous nephrolithotomy

BACKGROUND

This study aimed to assess the efficacy and safety of minimally invasive percutaneous nephrolithotomy (MPCNL) versus standard percutaneous nephrolithotomy in patients with renal and upper ureteric stones.

METHODS

We conducted a pooled analysis on randomized controlled trials (RCTs). The eligible RCTs were selected from the following databases: MEDLINE, Embase, Web of Science, and the Cochrane Library. The reference lists of retrieved studies were also investigated.

RESULTS

Our analysis included 10 RCTs with 1612 patients. Pooled data from 10 RCTs revealed the following: stone-free rate (odds ratio = 1.46, 95% confidence interval (CI) [1.12,1.88], P = .004), operative time (mean difference [MD]  = 4.10, 95% CI [-1.37,9.56], P = .14), length of hospital stay (MD = -15.31, 95% CI [-29.43,-1.19], P = .03), hemoglobin decrease (MD = -0.86, 95% CI [-1.19,-0.53], P < .00001), postoperative fever (MD = 0.83, 95% CI [0.49,1.40], P = .49), and urine leakage (MD = 0.59, 95% CI [0.25,1.37], P = .22). Besides, we performed sub-group analysis based on vacuum suction effect and multiple kidney stones. For vacuum suction effect, it revealed the following: stone-free rate in vacuum suction group (P = .007) and in non-vacuum suction group (P = .19). Operative time in vacuum suction group (P = .89), non-vacuum suction group (P = .16). Postoperative fever in vacuum suction group (P = .49), non-vacuum suction group (P = .85).

CONCLUSION

This pooled analysis indicated that MPCNL was a safe and effective method for treating renal stones compared with standard percutaneous nephrolithotomy. Besides, the vacuum suction effect in MPCNL played a more important role. When it comes to multiple or staghorn stones, the longer operative time in MPCNL could not be ignored.

Percutaneous nephrolithotomy with suction: is this the future?

PURPOSE OF REVIEW

The armamentarium of percutaneous nephrolithotomy (PCNL) and the strategy to perform the procedure is constantly evolving. The innovation and development in techniques lead to further miniaturization in PCNL devices and change the lithotripsy and stone removal strategy. Suctioning in PCNL offers urologist a new conception in renal stone management. The present review evaluates the latest results on efficacy, safety and feasibility of suctioning PCNL techniques.

RECENT FINDINGS

Recent literature reported the outcomes of different suctioning PCNL techniques. Most of these studies demonstrated good efficacy when comparing conventional PCNL. Suctioning PCNL improving the lithotripsy efficiency to enhance the stone-free rate (SFR) and reducing renal pelvic pressure to attenuate postoperative infectious complications. The advantage of suction also helps overcome the limitation of potentially higher intrarenal pressure and prolonged operative time in Mini-PCNL.

SUMMARY

PCNL with suctioning represents a valuable new tool in the armamentarium of modern endourologists. This innovative approach can offer improved safety and efficacy with lower complications rates and higher cost effectiveness than the traditional PCNL technique.

Miniaturized percutaneous Nephrolithotomy without antibiotic prophylaxis: a single institution experience

PURPOSE

To assess the feasibility of sparing routine antibiotic prophylaxis in patients without preoperative urinary tract infection (UTI) undergoing a miniaturized percutaneous nephrolithotomy (mPCNL).

PATIENTS AND METHODS

A retrospective, monocentric study was conducted to evaluate the outcome of a modified perioperative antibiotic management strategy according to the principles of antibiotic stewardship (ABS). From December 2015 patients undergoing mPCNL for kidney stone with preoperative unremarkable urine culture no longer received an antibiotic prophylaxis (NoPAP). The NoPAP group was compared to mPCNL patients who received standard antibiotic prophylaxis (PAP) in the two years before. Analysis focused on postoperative complications. Logistic regression analysis was performed to identify potential risk factors.

RESULTS

Postoperative fever occurred in 8% of the NoPAP and 9% of the PAP patients (p = 0.764). Clavien 1-3 complications did not differ between groups with 33% in the NoPAP and 41% in the PAP (p = 0.511). No Clavien 4-5 complications were seen. A (partial) staghorn stone (HR 5.587; p = 0.019) and an infectious stone component (HR 6.313; p = 0.003) were identified as significant risk factors for postoperative fever. By sparing routine antibiotic prophylaxis the overall antibiotic usage was reduced from 100% (PAP) to 9% (NoPAP).

CONCLUSION

Patients with negative preoperative UC, a none-staghorn stone and no history of recurrent UTI or infectious stones may not need routine antibiotic prophylaxis prior to mPCNL. A prospective validation is warranted.

Effect of Active Aspiration and Sheath Location on Intrapelvic Pressure During Miniaturized Percutaneous Nephrolithotomy

OBJECTIVE

To evaluate the effects of location of the tip of percutaneous sheath and nephroscope in the collecting system together with active aspiration on the Intrapelvic pressure measurements (IPP) during miniaturized percutaneous nephrolithotomy (miniPNL).

MATERIALS AND METHODS

The data of 20 patients underwent miniPNL in supine position was collected prospectively. IPP measurements were done with an 8 Fr urodynamic pressure measurement catheter in 4 different settings with respect to location of tip of sheath and nephroscope. All 4 settings were repeated with active aspiration. Totally measurements were done and compared in 8 different settings for 90 seconds in each patient.

RESULTS

Highest mean IPP measurements were recorded in setting II (35.3 ± 11.8 cm H2O) where the sheath was located in the calyx and the tip of the nephroscope was in the renal pelvis. When active aspiration was applied, the mean pressure measurements were significantly lower than the counterpart settings without aspiration (all P values <.0001). When the active aspiration was applied, intrarenal pressure measurements did not exceed 40 cm H2O in any settings in any of the patients.

CONCLUSION

Location of the tip of the sheath and the nephroscope has significant effect on IPP measurements. Active aspiration significantly lowers the IPP and keeps it <40 cm H2O. Endourologists should be aware of possible alterations in IPP during miniPNL and active aspiration should be kept in mind as an effective solution to decrease the risk of complications related to high IPP.

Super-mini percutaneous nephrolithotomy (PCNL) vs standard PCNL for the management of renal calculi of <2 cm: a randomised controlled study

OBJECTIVE

To compare the effectiveness and safety of standard percutaneous nephrolithotomy (sPCNL) and super-mini PCNL (SMP).

PATIENTS AND METHODS

A total of 150 patients presenting with renal calculi of <2 cm were randomised to either sPCNL (Group 1) or SMP (Group 2). Randomisation was based on centralised computer-generated numbers. Variables studied included: stone-free rates (SFRs), operative time, intra- and postoperative complications, postoperative pain score, analgesic requirement, and hospital stay. Statistical analysis was performed using a t-test or Mann-Whitney U-test for continuous variables and chi-squared test or Fisher's exact test for categorical variables.

RESULTS

Between September 2018 and April 2019, 75 patients were included in each group. The SFRs of the groups were similar (97.33 vs 98.66%, P = 0.56). The mean (sd) operative time was significantly longer in Group 2, at 36.40 (14.07) vs 23.12 (11.96) min (P < 0.001). The mean (sd) decrease in haemoglobin was significantly less in Group 2, at 3.0 (4.9) vs 7.5 (6.5) g/L (P < 0.001). The mean (sd) pain score at 24 h was significantly lower in Group 2, at 0.3 (0.46) vs 0.75 (0.53) (P < 0.001). The mean (sd) analgesic requirement was significantly less in Group 2, at 67 (22.49) vs 91.5 (30.56) mg tramadol (P < 0.001). The mean (sd) hospital stay was significantly less in Group 2, at 28.38 (3.6) vs 39.84 (3.7) h (P < 0.001).

CONCLUSIONS

SMP is equally as effective as sPCNL for managing renal calculi of <2 cm, with improved safety. Although SMP is associated with a longer operative time, it has a significantly lower incidence of bleeding and postoperative pain, and a shorter hospital stay.

Consultation on kidney stones, Copenhagen 2019: lithotripsy in percutaneous nephrolithotomy

PURPOSE

To evaluate the balance between existing evidence and expert opinions on the safety and efficacy of new technological improvements in lithotripsy techniques for percutaneous nephrolithotomy (PCNL).

METHODS

A scoping review approach was applied to search literature in Pubmed, Embase, and Web of Science. Consensus by key opinion leaders was reached at a 2-day meeting entitled "Consultation on Kidney Stones: Aspects of Intracorporeal Lithotripsy" held in Copenhagen, Denmark, in September 2019.

RESULTS

New-generation dual-mode single-probe lithotripsy devices have shown favourable results compared with use of ballistic or ultrasonic lithotripters only. However, ballistic and ultrasonic lithotripters are also highly effective and safe and have been the backbone of PCNL for many years. Compared with standard PCNL, it seems that mini PCNL is associated with fewer bleeding complications and shorter hospital admissions, but also with longer operating room (OR) time and higher intrarenal pressure. Use of laser lithotripsy combined with suction in mini PCNL is a promising alternative that may improve such PCNL by shortening OR times. Furthermore, supine PCNL is a good alternative, especially in cases with complex renal stones and large proximal ureteric stones; in addition, it facilitates endoscopic combined intrarenal surgery (ECIRS).

CONCLUSION

Recent technological improvements in PCNL techniques are promising, but there is a lack of high-level evidence on safety and efficacy. Different techniques suit different types of stones and patients. The evolution of diverse methods has given urologists the possibility of a personalized stone approach, in other words, the right approach for the right patient.

Vacuum-assisted mini-percutaneous nephrolithotomy: a new perspective in fragments clearance and intrarenal pressure control

PURPOSE

To describe the vacuum-assisted mini-percutaneous nephrolithotomy (vmPCNL) technique performed via the 16Ch ClearPetra sheath, to evaluate its outcomes and to analyze intrarenal pressure (IRP) fluctuations during surgery.

METHODS

Data from all consecutive vmPCNL procedures from September 2017 to October 2019 were prospectively collected. Data included patients' and stones characteristics, intra and peri-operative items, post-operative complications and stone clearance. Patients undergoing vmPCNL from March to October 2019 were submitted to IRP measurement during surgery.

RESULTS

A total of 122 vmPCNL procedures were performed. Median stone volume was 1.92 cm³. Median operative time was 90 min and median lithotripsy and lapaxy time was 28 min. Stone clearance rate was 71.3%. Thirty-one (25.2%) patients experienced post-operative complications, seven of which were Clavien 3. Postoperative fever occurred in nine (7.4%) patients and one (0.8%) needed a transfusion. No sepsis were observed. IRPs were measured in 22 procedures. Mean IRP was 15.3 cmH₂O and median accumulative time with IRP > 40.78 cmH₂O (pyelovenous backflow threshold) was 28.52 sec. Maximum IRP peaks were reached during the surgical steps when aspiration is closed (mainly pyelograms), whereas during lithotripsy and suction-mediated lapaxy, the threshold of 40.78 cmH₂O was overcome in three procedures.

CONCLUSIONS

vmPCNL is a safe procedure with satisfactory stone clearance rates. Mean IRP was always lower than the threshold of pyelo-venous backflow and the accumulative time with IRP over this limit was short in most of the procedures. During lithotripsy and vacuum-mediated lapaxy, IRP rarely raised over the threshold.

Enhanced super-mini-PCNL (eSMP): low renal pelvic pressure and high stone removal efficiency in a prospective randomized controlled trial

OBJECTIVE

In the present prospective randomized controlled trial (RCT), enhanced-SMP (eSMP) and conventional Chinese mini-PCNL (mPCNL) were compared to test the low renal pelvic pressure (RPP) and high stone removal efficiency in eSMP.

MATERIALS AND METHODS

Hundred patients with 2-5 cm renal calculus were enrolled. Renal pelvic pressure, operation time, lithotripsy time, removed stone volume, and complications were compared between eSMP and mPCNL statistically.

RESULTS

There was no significant difference in removed stone volume between mPCNL and eSMP (8.09 ± 3.36 vs. 7.88 ± 3.07 mm³, t = 0.320, p = 0.750), lithotripsy time in mPCNL was longer than eSMP (49.6 ± 19.5 vs. 34.9 ± 14.2 min, t = 4.152, p < 0.001), thus stone removal efficiency was higher in eSMP (13.71 ± 1.18 vs. 9.82 ± 1.24 mm³/h, t = 15.499, p < 0.001). Intra-operative RPP in mPCNL was higher than eSMP (17.72 ± 3.33 vs. 12.03 ± 2.37 mmHg, t = 9.524, p < 0.001); accumulated time of backflow status (RPP > 30 mmHg) in mPCNL was longer than eSMP (23.3 ± 16.9 vs. 3.7 ± 4.2 s, t = 7.710, p < 0.001). There was no significant difference in postoperative fever rate between mPCNL and eSMP (12.77% vs. 4.34%, χ² = 2.095, p = 0.148), nor final stone-free rate (87.2% vs. 91.3%, χ² = 0.401, p = 0.526). Hospital stay in eSMP was shorter than mPCNL (2.54 ± 0.72 vs. 3.00 ± 0.88, t = 2.724, p = 0.008).

CONCLUSION

Enhanced SMP (eSMP) was safe and effective in the management of 2-5 cm renal calculus. It can keep a lower renal pelvic pressure and a higher stone removal efficiency when compared to conventional Chinese mini-PCNL.

CLINICAL TRIAL REGISTRATION

NC03206515.

Use of a Novel Vacuum-Assisted Access Sheath in Minimally Invasive Percutaneous Nephrolithotomy: A Feasibility Study

Objective: To assess the safety and efficacy of a novel vacuum-assisted access sheath (VAAS) in minimally invasive percutaneous nephrolithotomy (MPCNL). Materials and Methods: Seventy-five consecutive patients with single renal pelvic stone were treated with MPCNL combined with a novel VAAS. Patients' demographics and surgical outcomes, as well as perioperative and postoperative data, were recorded. Matched-pair analysis in a 1:1 scenario was done in patients who underwent MPCNL by peel-away access sheath (PAAS). All MPCNL was done with a rigid 12F mini-nephroscope and an 18F access sheath. MINDRAY-PM9000 monitor was used to record the renal pelvic pressure (RPP) data. Results: Patients' demographics, stone size, burden, and density (HU) were comparable between the two groups. Operative time was significantly shorter in the study group, at a mean of 32.4 ± 9.6 vs 46.2 ± 11.8 minutes (p < 0.001). The immediate stone-free rate was 89.3% for the VAAS group and 77.3% for the PAAS group (p = 0.049). Patients in the VAAS group had a lower visual analogue pain scale score at postoperative 6 and 24 hours. Mean perioperative RPP was lower in the VAAS group (10.3 ± 4.3 vs 17.8 ± 5.1 mmHg, p < 0.001). More than 50 seconds of accumulative time of high RPP (>30 mmHg) was shown in 13 patients of the VAAS group vs 30 of the PAAS group (p = 0.002). Conclusion: Combining VAAS with high-power holmium laser in MPCNL significantly improves the efficiency of stone retrieval with low RPP. This novel approach also reduces operative time, postoperative fever, and pain due to its simultaneous suction property.

Tract sizes in percutaneous nephrolithotomy: does miniaturization improve outcome?

PURPOSE OF REVIEW

To provide a summary of surgical outcomes in percutaneous nephrolithotomy (PCNL) according to various techniques and tract sizes.

RECENT FINDINGS

Recent literature in this field concluded that standard PCNL (sPCNL) remains the optimal treatment for stones between 1 and 2.5 cm and can be managed with tracts 14-20 F, whereas small stones less than 1.5 cm can be treated with tracts under 14 F. According to new datasets, smaller tracts can be equally effective in the treatment and might offer the possibility to reduce bleeding, length of hospital stay, postoperative pain as well as overall complication rates when compared with sPCNL. On the other hand, longer operative time as well as lower stone-free rates, which have been the main drawbacks of the miniaturized approach, have recently shown to be comparable with sPCNL.

SUMMARY

At present, tract size is a highly debatable topic in percutaneous stone therapy. New systems for miniaturized PCNL have been developed to achieve comparable stone-free rates while reducing the incidence of common complications. The adoption of these techniques demands skilled surgeons and institutional investment for the acquisition of new equipment.

Treatment of a patient with total urinary calculi: a case report

Urinary tract stones are a general term for stone disease in various parts of the urinary system and are common diseases of the urinary system. According to the location of the stone, it is divided into kidney stones, ureteral stones, bladder stones, urethra stones. Total urinary calculi occur less frequently, usually accompanied by severe clinical symptoms and difficult to treat. A 76-year-old man was admitted to hospital with repeated bladder stones for 7 years, repeated dysuria with frequent urination and dysuria for 2 months. After admission, the patient improved the relevant examination, and the patient was finally diagnosed with total urinary calculi combined with infection. After a series of orderly and effective treatments, especially the completion of the one-stage operation, the patient recovered smoothly and was discharged. Complicated whole-course urolithiasis is relatively rare and a single operation of total urinary calculi is feasible.

The Clinical Application of New Generation Super-Mini Percutaneous Nephrolithotomy in the Treatment of ≥20 mm Renal Stones

Purpose: To evaluate the safety and efficacy of new generation super-mini percutaneous nephrolithotomy (New-SMP) in the treatment of ≥20 mm renal stones. Methods: We retrospectively analyzed the New-SMP procedures (14F) performed in the cases with ≥20 mm renal stones between April 1, 2016 and July 1, 2018. The cases with ipsilateral Double-J stent and/or nephrostomy tube preoperatively, ipsilateral ureteral stone, uncorrected coagulopathy, active urinary tract infection, congenital abnormalities, and urinary diversion were excluded. Results: Of totally 188 included cases, 8 (4.3%) were children (≤14 years) and 180 (95.7%) were adults. The cases had a mean age of 47.14 ± 15.13 years, a mean stone size of 31.57 ± 9.8 mm, and a mean S.T.O.N.E score of 7.02 ± 0.73. The New-SMP took a median operative time of 35 minutes (range 6-127). A total of 173 (92%) cases received single-access-tract procedure. The drop in hematocrit was 14.62 ± 8.36 g/L after the procedure. The serum white blood cells (WBCs) increased to 2.58 ± 2.89 × 10⁹/L. The mean hospital stay was 2.4 ± 1.5 days. New-SMP had a stone-free rate of 84% within 48 hours and 91.5% at 3 months postoperatively. Five (2.7%) cases required auxiliary procedures. The tubeless rate was 87.2%, including 44.1% cases with total tubeless, 41.5% cases with Double-J stent, and 1.6% cases with ureteral catheter. Totally 9.6% cases got fever (>38°C), 1.0% cases had urosepsis, and no cases developed shock. In addition, no transfusion and arterial embolization were required. Conclusions: New-SMP could be a safe and efficacious approach for the management of ≥20 mm renal stones. The novel modified technique and system may extend the indication of SMP to large renal stones. Further clinical studies and direct comparisons between New-SMP and other available modalities of percutaneous nephrolithotomy are required.

Characterization of Flow-Caused Intrarenal Pressure Conditions During Percutaneous Nephrolithotomy In Vitro

PURPOSE

To investigate renal pelvic pressures during percutaneous nephrolithotomy (PCNL) in the standard, mini, and ultramini PCNL systems.

METHODS

We studied an ultramini PCNL system (UMP, outer shaft diameter 13F), a mini PCNL system (MPCNL, shaft 18F, nephroscope 12F), and a standard PCNL system (SPCNL, shaft 27F, nephroscope 24F). Pressure profiles were first investigated in an open model setup, subsequently in a closed model, and finally in an ex vivo porcine kidney. Measurements were determined with the nephroscope in an advanced and pulled-back position for all models.

RESULTS

In the advanced position, maximum pressures of 41.61 ± 0.20 mmHg (UMP), 15.61 ± 0.15 mmHg (MPCNL), and 15.46 ± 0.14 mmHg (SPCNL) were measured in the closed model. In the pulled-back position, maximum pressures were 16.04 ± 0.22 mmHg (UMP), 17.02 ± 0.11 mmHg (MPCNL), and 20.50 ± 0.11 mmHg (SPCNL). In the ex vivo porcine kidney model, maximum pressures were 13.81 ± 6.04 mmHg (UMP), 5.64 ± 0.21 (MPCNL), and 9.21 ± 0.52 (SPCNL) with the nephroscope pushed to end position. After retracting the nephroscope from the outer shaft, pressures in all systems did not exceed 10 mmHg.

CONCLUSIONS

The maximum pressures achieved with the three PCNL systems in all three models were kept below the 30 mmHg critical threshold value. High pressures were only determined for the UMP system with the nephroscope pushed to its end position. This was attributed to the conical shape of the nephroscope, which occupies the space between the nephroscope and outer shaft, resulting in outflow obstruction.

Perioperative antibiotic prophylaxis for stone therapy

PURPOSE OF REVIEW

To give an overview about state-of-the-art antibiotic prophylaxis in urolithasis therapy and focus on recent publications in this field.

RECENT FINDINGS

The number of high-quality publications within the recent time is limited. Preoperative inflammatory blood parameters like C-reactive protein and erythrocyte-sedimentation rate might help in prediction of postoperative systemic inflammatory response syndrome (SIRS) after percutaneous nephrolithotomy (PCNL). White blood cell count is nonpredictive for urinary tract infection (UTI) in patients with acute renal colic. In patients with low risk for infectious complications, antibiotic prophylaxis during shock-wave lithotripsy (SWL) is unnecessary and single-dose antibiotics are comparably effective as prolonged antibiotic usage during PCNL and ureterorenoscopy (URS).

SUMMARY

Current findings support the American Urological Association (AUA) and European Association of Urology (EAU) guideline recommendations for a risk-adapted minimal antibiotic usage. Single-dose antibiotic prophylaxis is sufficient for low-risk PCNL and URS. For SWL no antibiotic prophylaxis is needed.

Development of an innovative intrarenal pressure regulation system for mini-PCNL: A preliminary study

Introduction

Miniaturized percutaneous nephrolithotomy (mini-PCNL) requires saline irrigation at high-pressures to maintain visual clarity. However, this may raise the intrarenal pelvic pressures (IRPs) beyond a safe range and may result in a higher complication rate. The aim of this study was to make and validate an automated pressure saline irrigation system to regulate IRPs during mini-PCNL.

Materials and Methods

A ureteric catheter was connected to an urodynamic machine and the minimum, maximum, and average IRPs reached during a standard 15 Fr mini-PCNL were measured in ten cases. Next, an intrarenal pressure regulation system (IPRS) was conceptualized, designed, patented, and constructed. IPRS was then tested on a mannequin model using the routine instruments. Lastly, the IPRS was evaluated on - five cases of 15 Fr mini-PCNL. The mean maximum IRP as recorded in the baseline data was set as the maximum permissible pressure on IPRS. The efficacy of IPRS was assessed by measuring the IRP, recorded in parallel, on both the IPRS and the urodynamic machine at various stages of the procedure.

Results

The mean maximum IRP reached during baseline evaluation was 25 cm of water which was set as the maximum permissible limit of the IPRS. Evaluation of the IRPS on mannequin models and validation clinical cases showed that IPRS measured the IRP accurately and prevented the pressure surge above the set limits Overall, higher IRPs were recorded during stone pulverization as compared to the other surgical steps.

Conclusions

The current IPRS is the first of its kind open platform, portable, automated pressure saline irrigation system. It precisely monitors and controls the IRP and has the potential to reduce the irrigation pressure-related complications.