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Injection of mediNiK®
Administration of mediNiK®
1. Use the endoscope to navigate within vision to the kidney stone fragments. Irrigate with physiological sterile saline solution (0.9 % NaCI) to ensure good visibility.
2. Stop irrigation. Slowly inject the blue base substance K1 in pulses through the working channel of the endoscope until the fragments to be removed are completely surrounded by blue K1. If more than one renal calyx is affected, repeat this step for each calyx individually.
Tip: Only use as much of the blue base substance K1 as necessary. This is then turned into a hydrogel by adding the second component, the yellow activator K2.
3. Carefully flush the working channel of the endoscope with 0.9 % NaCI.
Caution: Avoid turbulence/dilution of the blue K1 by flushing the working channel too intensively. Pull the endoscope back slightly.
4. Inject the yellow K2 carefully and slowly through the previously flushed working channel. Move the endoscope slowly in the direction of the affected renal calyx(es).
Caution: Avoid turbulence in the blue K1 by injecting too quickly. Irrespective of the amount of blue base substance K1 used, the entire content of the yellow activator K2 syringe (11 ml) should be injected.
5. Wait approx. 3 minutes until the hydrogel has reached the desired firmness. Shortening the waiting time – and diluting the yellow activator K2 by flushing – results in a softer hydrogel.
6. Carefully grasp and remove the hydrogel clot with the grasping instrument. Flushing can now be restarted at low intensity.
Caution: The grasper can cut the hydrogel if it is closed too tightly.
Following administration
Ensure that all hydrogel clots have been removed. However, if hydrogel clots remain, these are – as a rule – dissolved by diuresis. The hydrogel can also be actively dissolved by adding a chelating agent (e.g. EDTA).
Repeating the procedure: If the procedure is repeated, all of the previously used yellow K2 must be completely flushed out of the kidney.
Single use: mediNiK® is intended for single use and must not be resterilized.
Disposal: The syringes filled with blue K1 and yellow K2 can be disposed of in accordance with the lowest internal hospital disposal standards. The hydrogel must be disposed of separately as it has come into contact with mucous membranes and/or urine.
Note:
All serious incidents occurring in connection with the device must be reported to the manufacturer and the competent authority of the Member State in which the user and/or patient is located (vigilanz@purenum.com).
Frequently asked questions about the use of mediNiK®
2. How many syringes do I need per patient/administration?
1 administration = 2 syringes (1 of component K1 + 1 of component K2)
3. How can you tell that a sufficient amount of the base substance K1 has been injected?
K1 is blue in color and transparent, creating a good color contrast on the monitor and ensuring that the stone fragments are visible. When all stone fragments are completely coated with the blue component, a sufficient amount has been administered.
4. How can I be sure that a sufficient amount of the activator K2 has been administered?
There is no need to ensure a precise mixing ratio. At least two to three times the amount of K2 should be injected compared to the previously introduced base substance K1. As overdose of the K2 activator is not possible, the entire contents of the syringe can be injected slowly (without turbulence).
5. Is it possible to administer too much mediNiK® (K1 or K2)?
With regard to the quantity of base substance K1, it makes sense to inject only enough to completely enclose all fragments according to the principle of as much as necessary, as little as possible. About 0.3 to 0.5 ml of K1 should be sufficient for one calyx, although several calices can be filled in succession before K2 is added. On the other hand, it is not possible to inject too much of the activator K2.
6. After adding component K2, no solid hydrogel is formed, or only a small amount. Why is that?
a. The flushing was not stopped before the administation of K1 and K1 was therefore "flushed out".
b. Component K2 was administered so quickly that component K1 was "flushed out" by the resulting turbulence.
c. Component K2 was administered too close to component K1, so that component K1 was "flushed out".
d. Too little of component K2 was used, and there was no visible yellowing of the total fluid in the kidney.
e. If it is not the first administration: Inadequate flushing, residual component K2 was still present in the kidney.
f. Not waiting long enough for the gel to form.
7. What happens if flushing is NOT turned off before injecting mediNiK®?
The base substance K1 is "flushed away" or diluted by the flow caused by flushing. The residual fragments to be retrieved are therefore insufficiently coated.
8. What happens if I do not administer a component?
If only one of the two components is administered, no gel formation will occur. Consequently, the residual fragments cannot be retrieved as expected.
9. What happens if I reverse the order of use?
If the activator K2 is administered first, K1 gel formation will occur instantaneously during the subsequent injection of base substance K1. The residual fragments will therefore be bound weakly or not at all by the hydrogel.
10. Do I need to apply pressure to the syringes to force the components out of the syringes?
The higher viscosity component K1 (base substance) requires slightly more force than component K2 (activator), especially if it is delivered through a catheter (which can be useful when using a reusable scope, for example). When administered directly via the working channel as we recommend, both components can be easily dosed. If it is not possible to administer the components K1 or K2, it may be because:
1) the selected catheter is too narrow.
2) there is a blockage in the catheter caused by residues of the other component that have not been flushed away.
3) the Tuohy Borst at the entrance to the working channel is tightened too much so that the cross-section of the catheter is reduced.
11. It is difficult to plunge the syringes when they are first pressed, is this normal?
Yes, the technical pressure point must be released first. This is done by briefly pressing in the plunger rod with the cap fixed in place, e.g. by placing the syringe on a solid surface, similar to other syringes from FARCO-PHARMA (e.g. Instillagel and Endosgel).
12. Can mediNiK® be administered a second time during surgery?
Yes, mediNiK® can even be administered several times to one patient. This requires the kidney to be well flushed with physiological saline solution so that no residues of component K2 are present. Residual K2 would lead to immediate gel formation upon readministration of K1 without the stone fragments being sufficiently coated.
Retrieval of renal stone fragments
14. Why does the hydrogel clot have to be pulled out "carefully"? What if I "lose" half of it?
The hydrogel is designed to be soft so that it can mold to the urinary tract or ureteral sheath. There is a constriction at the junction between the renal pelvis and the ureteral sheath. If the hydrogel is pulled through too quickly at this point, the part protruding from the extraction basket may be sheared off. This part must be retrieved in a further step. As the gel is located directly inside the renal pelvis, it is easy to grasp and subsequently retrieve the fragments.
15. What happens if residues of mediNiK® remain in the kidney after the procedure?
Residues of mediNiK® remaining in the kidney do not pose a risk to the patient. Natural diuresis reverses gel formation. Initially, the gel becomes softer and softer until it turns completely back into a liquid and is excreted by the patient in the urine.
Following administration
17. Can leftover mediNiK® be used for another operation?
No. The principle is that opened and used syringes may only be used in one patient for a single operation.
18. How can I isolate the retrieved stone fragments from the hydrogel for analysis?
There are two possibilities, in principle:
1) The stones can be mechanically removed from the hydrogel and rinsed with sufficient water.
2) The hydrogel is dissolved by placing it in a chelating agent (e.g. EDTA) so that isolated stone fragments can be sent for analysis.
Training video on the use of mediNiK®
Publications
ABOUT mediNiK®
Open label, Randomized, Multicentric Study to Evaluate Safety, Tolerability and Performance of mediNiK in Comparison to Standard of Care in Removal of Kidney Stones
German Clinical Trials Register [Internet] Cologne/Bonn Bundesinstitut für Arzneimittel und Medizinprodukte BfArM (Germany); 2022; DRKS-ID DRKS00030532; Open label, Randomized, Multicentric Study to Evaluate Safety, Tolerability and Performance of mediNiK in Comparison to Standard of Care in Removal of Kidney Stones; 2022 Oct 25 [cited 2024 May 03]; [about 9 pages]. Available from: https://drks.de/search/de/trial/DRKS00030532
Brief summary of results:
mediNiK is an innovative two-component hydrogel system, developed for intrarenal embedding and retrieval of kidney stone fragments after ureterorenoscopy with lithotripsy (URS). This hydrogel is intended to be used when stone fragments are too small to be removed with conventional grasping tools. To evaluate safety, tolerability and performance data of mediNiK for the first time, an open-label, randomized, multicenter study was conducted. At five sites in Germany, a total of 70 patients were examined, 65 of whom were included in the study, 32 only with standard URS procedure, and 33 with URS and subsequent mediNiK usage. At the end of the complete follow-up period, 17 (URS) and 23 (URS + mediNiK) patients remained for full analysis. Main reason for exclusion from analysis set can be attributed to protocol deviations (i.e. no stones were collected and quantified). In this study, mediNiK was shown to be safe. No incidences of device-related adverse events for either of the two groups (URS vs. URS + mediNiK) were observed. Furthermore, the occurrence of treatment-emergent adverse events following surgery was comparable between the groups. Main performance analysis of mediNiK showed a clear tendency of higher number of removed small stone fragments <1 mm (in total: 1716 stones; 74.61 per subject) compared to standard URS procedure alone (in total 209 stones; 12.29 per subject). Using more appropriate statistical methods considering the non-Gaussian distribution of stones in the patients, mediNiK even demonstrated to increase statistically significantly the number of removed stones, thereby proving to enable a more efficient stone removal in particular of small sized fragments. In the mediNiK group, cumulatively 2026 stones were removed, with 1492 stones < 0.5 mm, 224 stones 0.5 mm to < 1 mm, and 310 stones ≥ 1 mm. In the URS group, cumulatively 327 stones were removed, with 194 stones < 0.5 mm, 15 stones 0.5 mm to < 1 mm, and 118 stones ≥ 1 mm. Thus, in the mediNiK group, on average 88.1 stones of all sizes were removed per subject while only 19.2 stones were removed in the URS group. Due to the attempt to remove smaller residual fragments <1 mm that otherwise could not be grasped with the basket and the initial lack of practice with this innovative hydrogel method, the duration of procedure using URS + mediNiK compared to standard URS alone differed (85.7 min vs. 66.8 min per subject). Negative effects on subjects were not observed. The ease of the kidney stone removal procedure was similar between the groups based on clinical investigator’s feedback. Thus, mediNiK did not appear to deteriorate the ease of kidney stone removal procedure. In summary, no significant differences were found with regard to safety of use. Hence, the use of mediNiK can be considered safe. Clinician responses to performance of mediNik were positive. Further analyses demonstrated that the addition of mediNiK to the standard URS procedure enables a more efficient removal in particular of stones of small sizes (<1 mm) than is currently technically possible with simple URS. A higher stone removal rate by means of mediNiK might therefore contribute to lowering recurrence rates of kidney stones, thus leading to better patient care.
Novel Biocompatible Adhesive to Remove Stone Dust:
Usability Trial in a Kidney Model
Hausmann T, Becker B, Gross AJ, Netsch C, Rosenbaum CM. Novel Biocompatible Adhesive to Remove Stone Dust: Usability Trial in a Kidney Model. J Endourol. 2021 Aug;35(8):1223-1228. doi: 10.1089/end.2020.0748. Epub 2021 Apr 15. PMID: 33559523.
Brief summary of results:
Introduction and Objective
“Clinically insignificant residual fragments” are an independent predictive factor for recurrence of nephrolithiasis. To improve the stone-free rates (SFR), we tested the viability of a novel bioadhesive system for intrarenal embedding and retrieval of residual fragments <1 mm in a kidney model.
Materials and Methods
All procedures were performed in a standardized setting, including a kidney model (Kidney module right, Samed GmbH, Dresden) in a plastic basin filled with water. We used a Viper URF flexible ureterorenoscope (fURS) (6.6/8F, Richard Wolf, Knittlingen). A mean amount of 138 mg (standard deviation [SD] ±32.2 mg) of sand grains (range, 0.2–0.8 mm) was inserted in renal calices of the kidney model. We assessed the extraction efficacy of fURS using the bioadhesive system. In total, eight different surgeons performed each one trial, respectively. The endoscopic and macroscopic SFR, the level of the surgeons’ experience, and the overall time of stone retrieval were evaluated. Additionally, a survey of the participants was conducted, to assess the contentment with this novel system.
Results
The extraction of the sand grains was only possible using the bioadhesive system, otherwise they were too small sized to grab with a retrieval basket. The total SFR was 84% (SD ±11.7%). The operation time (p = 0.052) and the percentage of extracted sand grains (p = 0.194) were not significantly different between experienced and less experienced surgeons. All participants stated that it was a promising technique, which they could imagine using on a daily basis.
Conclusions
The bioadhesive system improves the SFR with fragments from 0.2 to 0.8 mm (0% vs 84%). Also, the performance of this operation is not dependent on the surgeon’s experience level. This method might improve the SFR in difficult anatomic conditions, that is, lower calices or anomalous kidneys.
Viability and biocompatibility of an adhesive system for intrarenal embedding and endoscopic removal of small residual fragments in minimally-invasive stone treatment in an in vivo pig model
Hein S, Schoeb DS, Grunwald I, Richter K, Haberstroh J, Seidl M, Bronsert P, Wetterauer U, Schoenthaler M, Miernik A. Viability and biocompatibility of an adhesive system for intrarenal embedding and endoscopic removal of small residual fragments in minimally-invasive stone treatment in an in vivo pig model. World J Urol. 2018 Apr;36(4):673-680. doi: 10.1007/s00345-018-2188-8. Epub 2018 Jan 24. PMID: 29368229.
Brief summary of results:
Purpose
To evaluate the viability and biocompatibility of a novel, patented bioadhesive system for intrarenal embedding and retrieval of residual fragments after endoscopic lithotripsy. Complete stone clearance via active removal of residual fragments (RF) after intracorporeal laser lithotripsy may be time-consuming and fail in many cases. Therefore, the novel adhesive has been developed and evaluated for the first time in an in vivo pig model in the present work.
Methods
Four female domestic pigs underwent flexible ureteroscopy (RIRS) or percutaneous nephrolithotomy (PNL) under general anesthesia (8 kidneys, 4 × RIRS, 4 × PNL) evaluating the bioadhesive system. Interventions: RIRS without adhesive system (sham procedure, kidney I); 3 × RIRS using the bioadhesive system (kidneys II–IV); and 4 × PNL using the bioadhesive system (V–VIII). We endoscopically inserted standardized human stone probes followed by comminution using Ho:YAG lithotripsy. The bioadhesive (kidney II–VIII) was then applied and the adhesive-stone fragment complex extracted. After nephrectomy, all kidneys were evaluated by two independent, blinded pathologists. Endpoints were the procedure’s safety and adhesive system’s biocompatibility.
Results
We observed no substantial toxic effects. We were able to embed and remove 80–90% of fragments. However, because of the pig’s hampering pyelocaliceal anatomy, a quantified, proportional assessment of the embedded fragments was compromised.
Conclusions
For the first time, we demonstrated the proven feasibility and safety of this novel bioadhesive system for embedding and endoscopically removing small RF in conjunction with a lack of organ toxicity in vivo.
New for Old–Coagulum Lithotomy vs a Novel Bioadhesive for Complete Removal of Stone Fragments in a Comparative Study in an Ex Vivo Porcine Model
Schoeb DS, Schoenthaler M, Schlager D, Petzold R, Richter K, Grunwald I, Wetterauer U, Miernik A, Hein S. New for Old-Coagulum Lithotomy vs a Novel Bioadhesive for Complete Removal of Stone Fragments in a Comparative Study in an Ex Vivo Porcine Model. J Endourol. 2017 Jun;31(6):611-616. doi: 10.1089/end.2017.0125. Epub 2017 May 8. PMID: 28385037.
Brief summary of results:
Objectives
To evaluate a recently reported new bioadhesive system for the retrieval of small residual fragments (RFs) after intracorporeal lithotripsy, we systematically compared this system with coagulum lithotomy in retrograde intrarenal surgery.
Materials and Methods: We extracted 30 human stone fragments (≤1 mm) in an ex vivo porcine kidney model using a flexible ureteroscope for three groups: (1) the novel bioadhesive, (2) autologous blood as a natural adhesive, and (3) (control group) a conventional retrieval basket. Each group consisted of 15 test runs. Outcomes were evaluated regarding the macroscopic stone-free rate (SFR), retrieval time, and number of ureteral passages.
Results
For groups 1 and 2, a significant advantage in stone clearance, mean retrieval time, and number of retrievals was detected compared to the control group (p = 0.001). The time and number of retrievals were significantly lower in group 1 (10:36 minutes, p = 0.001) than in group 2 (26:12 minutes, p = 0.001), with shorter clotting time and better visibility.
Conclusions
These data show the general feasibility of intrarenal RF embedding to improve the SFR. Our data furthermore suggest the superiority of the artificial bioadhesive embedding agent over the application of native blood. Further in vivo studies and other research are necessary to confirm the adhesive’s effect in patients.
Novel Biocompatible Adhesive for Intrarenal Embedding and Endoscopic Removal of Small Residual Fragments after Minimally Invasive Stone Treatment in an Ex Vivo Porcine Kidney Model: Initial Evaluation of a Prototype
Hein S, Schoenthaler M, Wilhelm K, Schlager D, Thiel K, Brandmann M, Richter K, Grunwald I, Wetterauer U, Miernik A. Novel Biocompatible Adhesive for Intrarenal Embedding and Endoscopic Removal of Small Residual Fragments after Minimally Invasive Stone Treatment in an Ex Vivo Porcine Kidney Model: Initial Evaluation of a Prototype. J Urol. 2016 Dec;196(6):1772-1777. doi: 10.1016/j.juro.2016.05.094. Epub 2016 May 30. PMID: 27256206.
Brief summary of results:
Purpose
Residual fragments related to endoscopic intracorporeal lithotripsy are a challenging problem. The impact of residual fragments remains a subject of discussion and growing evidence highlights that they have a central role in recurrent stone formation. Therefore, we developed a novel bioadhesive system for intrarenal embedding and retrieval of residual fragments after endoscopic lithotripsy in an ex vivo porcine kidney model.
Materials and Methods
In a standardized setting 30 human stone fragments 1 mm or less were inserted in the lower pole of an ex vivo porcine kidney model. We assessed the extraction efficacy of flexible ureteroscopy using the bioadhesive system in 15 preparations and a conventional retrieval basket in 15. Outcomes were compared regarding the endoscopic and macroscopic stone-free rate, and overall time of retrieval.
Results
Embedding and retrieving the residual fragment-bioadhesive complex were feasible in all trial runs. We observed no adverse effects such as adhesions between the adhesive and the renal collecting system or the instruments used. The stone-free rate was 100% and 60% in the bioadhesive and conventional retrieval groups, respectively (p = 0.017). Mean retrieval time was significantly shorter at 10 minutes 33 seconds vs 36 minutes 56 seconds in the bioadhesive group vs the conventional group (p = 0.001).
Conclusions
This novel method involving adhesive based complete removal of residual fragments from the collecting system has proved to be feasible. Our evaluation in a porcine kidney model revealed that this technology performed well. Further tests, including inpatient studies, are required to thoroughly evaluate the benefit and potential drawbacks of bioadhesive based extraction of residual fragments after intracorporeal lithotripsy.
About medical need
Endoscopically Determined Stone Clearance Predicts Disease Recurrence Within 5 Years After Retrograde Intrarenal Surgery
Hein S, Miernik A, Wilhelm K, Schlager D, Schoeb DS, Adams F, Vach W, Schoenthaler M. Endoscopically Determined Stone Clearance Predicts Disease Recurrence Within 5 Years After Retrograde Intrarenal Surgery. J Endourol. 2016 Jun;30(6):644-9. doi: 10.1089/end.2016.0101. Epub 2016 Apr 22. PMID: 27021947.
Brief summary of results:
Objective
To assess stone-related events (SREs) requiring retreatment in a series of 100 consecutive patients treated by retrograde intrarenal surgery (RIRS) for renal stones and to evaluate potential risk factors thereof.
Patients and Methods
The primary outcome was incidence of SRE (medical or surgical treatment). Secondary outcomes included side of SRE, time to SRE, and late complications. Analysis of potential risk factors included high-risk stone formers (HRSFs), obesity, high stone burden, and lower pole stones. In addition, we evaluated endoscopically determined small residual fragments (SRF) of <1 mm (i.e., fragments too small for retrieval) as an independent risk factor.
Results
Eighty-five of the 99 patients were followed up for a mean of 59 months (31–69), among whom 26 (30.1%) had SRE. Thirty-four of the 85 (40%) patients were HRSFs, 22 of whom experienced SRE (both sides) during follow-up (64.7%, p < 0.001). Eight of the 17 patients (47.1%) with SRF experienced ipsilateral side SRE compared with 13 (19.1%) of the 68 without SRF (p = 0.022, hazard ratio 2.823, 95% confidence interval [95% CI] 1.16, 6.85). Risk for ipsilateral SRE was unaffected by the presence of SRF among HRSFs (p = 0.561). Of low-risk patients with SRF, 33.3% experienced ipsilateral SRE, while those without SRF experienced no ipsilateral SRE (p < 0.001).
Conclusion
Endoscopically determined stone clearance predicts disease recurrence within 5 years after RIRS. Even SRF are an important risk factor for future stone-related (ipsilateral) events; therefore, patients with residual fragments of any size should not be labeled “stone free” and endoscopic stone treatment should aim at complete stone clearance.
Natural History of Post-Treatment Kidney Stone Fragments: A Systematic Review and Meta-Analysis
Brain E, Geraghty RM, Lovegrove CE, Yang B, Somani BK. Natural History of Post-Treatment Kidney Stone Fragments: A Systematic Review and Meta-Analysis. J Urol. 2021 Sep;206(3):526-538. doi: 10.1097/JU.0000000000001836. Epub 2021 Apr 27. PMID: 33904756.
Brief summary of results:
Purpose
We assessed the literature around post-treatment asymptomatic residual stone fragments and performed a meta-analysis. The main outcomes were intervention rate and disease progression.
Materials and Methods
We searched Ovid®, MEDLINE®, Embase™, the Cochrane Library and ClinicalTrials.gov using search terms: “asymptomatic”, “nephrolithiasis”, “ESWL”, “PCNL”, “URS” and “intervention.” Inclusion criteria were all studies with residual renal fragments following treatment (shock wave lithotripsy, ureteroscopy or percutaneous nephrolithotomy). Analysis was performed using ‘metafor’ in R and bias determined using Newcastle–Ottawa scale.
Results
From 273 articles, 18 papers (2,096 patients) had details of intervention rate for residual fragments. Aggregate intervention rates for ≤4 mm fragments rose from 19% (20 months) to 22% (50 months), while >4 mm fragments rose from 22% to 47%. Aggregate disease progression rates for ≤4 mm rose from 25% to 47% and >4 mm rose from 26% to 88%. However, there was substantial difference in definition of “disease progression.” Meta-analysis comparing >4 mm against ≤4 mm fragments: intervention rate for >4 mm (vs ≤4 mm): OR=1.50 (95% CI 0.70–2.30), p <0.001, I2=67.6%, tau2=0.48, Cochran’s Q=11.4 (p=0.02) and Egger’s regression: z=3.11, p=0.002. Disease progression rate for >4 mm: OR=0.06 (95% CI −0.98–1.10), p=0.91, I2=53.0%, tau2=0.57, Cochran’s Q=7.11 (p=0.07) and Egger’s regression: z=−0.75, p=0.45. Bias analysis demonstrated a moderate risk.
Conclusions
Larger post-treatment residual fragments are significantly more likely to require further intervention especially in the long term. Smaller fragments, although less likely to require further intervention, still carry that risk. Notably, there is no significant difference in disease progression between fragment sizes. Patients with residual fragments should be appropriately counselled and informed decision-making regarding further management should be done.
Clearance rates of residual stone fragments and dusts after endoscopic lithotripsy procedures using a holmium laser: 2-year follow-up results
Kang M, Son H, Jeong H, Cho MC, Cho SY. Clearance rates of residual stone fragments and dusts after endoscopic lithotripsy procedures using a holmium laser: 2-year follow-up results. World J Urol. 2016 Nov;34(11):1591-1597. doi: 10.1007/s00345-016-1807-5. Epub 2016 Mar 21. PMID: 27000560.
Brief summary of results:
Purpose
To investigate the spontaneous clearance rates of remnant particles following miniaturized percutaneous nephrolithotomy (mini-PCNL) and retrograde intrarenal surgery (RIRS).
Methods
Among 624 patients who underwent mini-PCNL or RIRS at our institution from 2011 to 2015, we collected data of 247 patients with 2 years of follow-up. Of these, we included 148 patients with unilateral renal stones between 10 and 30 mm, as well as remnant particles after surgery. The size criteria of dusts and residual fragments (RFs) were, respectively, <1 and <3 mm.
Results
After excluding 22 patients, 126 patients (RFs = 21, dusts = 98, and both RFs and dusts = 7) were analyzed. Mean age was 56.5 (±14.4) years, and mean stone size was 19.5 (±12.5) mm. The mean follow-up period was 18.5 (± 12.9) months. In patients whose remnant particles were naturally eliminated following lithotripsy, the mean stone passage time was 9.0 (±9.3) months in the dusts and 13.9 (±11.1) months in the RFs groups (P = 0.135). Remnant particles disappeared in 42 out of 105 patients (40.0 %) in dusts and 7 out of 28 patients (25.0 %) in RFs groups (P = 0.187). The size of dusts and RFs increased, respectively, in 18.1 % (19/105) and 28.6 % (8/28) of patients with remnant particles during the follow-up period.
Conclusions
The presence of dusts and RFs was poor prognostic factors in patients underwent renal stone surgery using a holmium laser. Complete residual stone removal by using a basket or dusts eradication by irrigation for an adequate time during surgery can be a good surgical strategy.
Removal of Small, Asymptomatic Kidney Stones and Incidence of Relapse
Sorensen MD, Harper JD, Borofsky MS, Hameed TA, Smoot KJ, Burke BH, Levchak BJ, Williams JC Jr, Bailey MR, Liu Z, Lingeman JE. Removal of Small, Asymptomatic Kidney Stones and Incidence of Relapse. N Engl J Med. 2022 Aug 11;387(6):506-513. doi: 10.1056/NEJMoa2204253. PMID: 35947709; PMCID: PMC9741871.
Brief summary of results:
Background
The benefits of removing small (≤6 mm), asymptomatic kidney stones endoscopically is unknown. Current guidelines leave such decisions to the urologist and the patient. A prospective study involving older, nonendoscopic technology and some retrospective studies favor observation. However, published data indicate that about half of small renal stones left in place at the time that larger stones were removed caused other symptomatic events within 5 years after surgery.
Methods
We conducted a multicenter, randomized, controlled trial in which, during the endoscopic removal of ureteral or contralateral kidney stones, remaining small, asymptomatic stones were removed in 38 patients (treatment group) and were not removed in 35 patients (control group). The primary outcome was relapse as measured by future emergency department visits, surgeries, or growth of secondary stones.
Results
After a mean follow-up of 4.2 years, the treatment group had a longer time to relapse than the control group (P<0.001 by log-rank test). The restricted mean (±SE) time to relapse was 75% longer in the treatment group than in the control group (1631.6±72.8 days vs. 934.2±121.8 days). The risk of relapse was 82% lower in the treatment group than the control group (hazard ratio, 0.18; 95% confidence interval, 0.07 to 0.44), with 16% of patients in the treatment group having a relapse as compared with 63% of those in the control group. Treatment added a median of 25.6 minutes (interquartile range, 18.5 to 35.2) to the surgery time. Five patients in the treatment group and four in the control group had emergency department visits within 2 weeks after surgery. Eight patients in the treatment group and 10 in the control group reported passing kidney stones.
Conclusions
The removal of small, asymptomatic kidney stones during surgery to remove ureteral or contralateral kidney stones resulted in a lower incidence of relapse than nonremoval and in a similar number of emergency department visits related to the surgery. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the Veterans Affairs Puget Sound Health Care System; ClinicalTrials.gov number, NCT02210650.)
The Predictive Factors for Readmission and Rehospitalization After Retrograde Intrarenal Surgery: The Results of RIRSearch Study Group
Dogan C, Yazici CM, Akgul HM, Ozman O, Basatac C, Cinar O, Siddikoglu D, Cakir H, Elmaagac B, Sancak EB, Onal B, Akpinar H. The Predictive Factors for Readmission and Rehospitalization After Retrograde Intrarenal Surgery: The Results of RIRSearch Study Group. J Endourol. 2022 Jan;36(1):56-64. doi: 10.1089/end.2021.0327. Epub 2021 Dec 9. PMID: 34235975.
Brief summary of results:
Purpose
Retrograde intrarenal surgery (RIRS) is a safe and effective treatment option for upper urinary tract stones smaller than 2 cm. Although several studies have documented perioperative and postoperative complications related to RIRS, there exists limited data regarding the readmission and rehospitalization of patients after RIRS. The aims of the study were to document the rates of readmission and rehospitalization after RIRS and to determine the predictive factors for readmission and rehospitalization.
Materials and Methods
In this study, we retrospectively analyzed patients who underwent RIRS for the treatment of renal stone disease and were unexpectedly readmitted to the hospital within 30 days after discharge. The hospital admission systems were used to determine readmissions and rehospitalizations. Readmission and rehospitalization rates, causes, and treatment procedures were evaluated. Univariate and multivariate analyses of clinicodemographic properties were performed to evaluate possible predictive factors for readmission and rehospitalization after RIRS.
Results
A total of 1036 patients were included in the study. Of these patients, 103 (9.9%) were readmitted to the hospital. Among these readmissions, 35 patients (33.9%) were rehospitalized and 14 (13.6%) underwent surgical intervention. The most common reasons for readmission were renal colic and fever. The presence of preoperative pyuria (odds ratio [OR] 1.86), stone volume (OR 1.54), postoperative complications (OR 3.66), and stone-free status (OR 0.46) were predictive factors for readmission, whereas hospitalization time (OR 1.32), postoperative complications (OR 9.70), and stone-free status (OR 0.06) were predictive factors for rehospitalization after RIRS.
Conclusion
Nearly 10% of patients who underwent RIRS were readmitted to the hospital within the first month after discharge, and some were rehospitalized. Preoperative pyuria, high stone volume, presence of postoperative complications, and low stone-free status predicted this readmission and rehospitalization. Clinicians must recognize these predictive factors and inform their patients about this possibility.
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