Exploring the use of suction evacuation sheath for surgical treatment of renal stones during ureteroscopy: An analysis of 2284 cases

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Exploring the use of suction evacuation sheath for surgical treatment of renal stones during ureteroscopy: An analysis of 2284 cases

https://doi.org/10.21203/rs.3.rs-4299045/v1

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Stone-free rates have drastically improved due to technological advancements in the field of endourology. One such advancement has been the use of suction evacuation sheaths (SES) during ureteroscopy (URS). Studies about outcomes after SES URS have been limited by small sample sizes. Here, we performed an analysis of postoperative outcomes of 2284 patients who underwent SES URS for the treatment of renal stone disease. We found that 86% of patients were stone-free at one month, with 50% of patients not requiring any repeat procedures for stone clearance. 1.28% experienced a major complication (Clavien-Dindo ≥ 3); 4.6% had postoperative fever, and 1.28% experienced sepsis after surgery. Ureteral injuries were seen in 1.5% of patients. Stone burden (OR 0.45 [0.33–0.62]) and the requirement of stent placement after lithotripsy (OR 0.71 [0.54–0.95]) were associated with lower SFR, while the use of basket during URS doubled the chances of being stone-free (OR 2.17 [1.33–3.53]). Age, while statistically significant, was not clinically relevant (OR 0.97 [0.96–0.98]). Our study is limited by its retrospective nature and the absence of a comparator group. Nonetheless, this study represents the largest cohort of patients to undergo SES URS for renal stone disease, and demonstrates that SES URS is a safe and efficacious technique for stone removal, with an SFR of 86% at one-month, and a 1.28% sepsis rate after surgery. Manual stone extraction in these patients can double their chances of being stone-free, thus highlighting that the use of SES alone is insufficient during URS.

Kidney Calculi

Nephrolithiasis

Ureteroscopy

Ureteroscopy (URS) is the surgical treatment of choice for patients with renal or proximal ureteral stones ≤ 2 cm [1, 2]. During URS, the stone is broken using an energy source (laser, pneumatic, ultrasonic energy), following which the fragments are retrieved by using a grasper or a basket forceps; saline irrigation must continue simultaneously to maintain visualization of the surgical field. The inconvenience of the instrumentation, and the possible decreased visualization, may result in longer operative times, predisposing patients to a higher risk of intraoperative and postoperative complications [3].

With technological advances in the field of stone treatment, stone free rates (SFR) have increased considerably [4]. One such technological innovation is the use of the suction evacuation sheath (SES) to improve the efficacy of fragment clearance during surgery. Continuous irrigation through the SES enables proper stone visualization, while simultaneously providing a negative pressure to extract stone dust and fragments. The suction evacuation may also lead to decreased intra-renal pressures (IRP), thus providing a protective effect to the renal parenchyma and decreasing bacterial translocation [5–7].

In this study, we aim to describe the efficacy of SES URS, as measured by SFR, one month after surgery. We also report on postoperative complication rates of this cohort, with emphasis on ureteral injury, infection rates, and retreatment rates.

Study setting, design and participants:

This is a retrospective study of patients who underwent URS at a single institution (IRB # ITCBM44678/12012). All patients were older than 18 years with confirmed stone disease in the upper urinary tract. All patients underwent standardized pre-operative assessment, including computerized tomography (CT) with or without contrast, renal ultrasound, and creatinine assessment. Preoperative stenting was performed in patients with signs of urinary tract obstruction or suspected infection.

Procedure Details and Postoperative Assessments:

Patients were placed in supine position and induced under general anesthesia. The suction evacuation sheath (ClearPetra, Well Lead Medical Inc.) was advanced over a guide wire within one centimeter of the stone. Following this, a ureteroscope (Olympus digital ureteroscope URV, URD, or semirigid OES Pro 6.8 Fr, depending on stone location) was inserted through the affected ureter to access the upper tract. Continuous pressurized irrigation was performed at a flow rate of 50–100 ml per minute to ensure proper visualization of the stone. Stone fragmentation was performed using Holmium-YAG Laser (200 µm, Boston Scientific /Lumenis 100 W). Stone clearance was performed until no stones were visualized by the surgeon. In cases where inadequate intra-operative stone clearance was noted, the surgeon used a basket to retrieve the remaining fragments. Stone fragments were subsequently sent for stone analysis to determine their composition. A double-J stent was placed at the end of the procedure when deemed necessary by the surgeon.

One month following surgery, patients underwent a CT scan. In most cases, a string was left attached to the stent and pulled on postoperative day 7 (either by the patient or in the clinic when needed). Patients with radiological evidence of residual disease underwent retreatment either by repeat URS, percutaneous nephrolithotomy (PCNL) or extracorporeal shockwave lithotripsy (ESWL).

Data variables:

Pre-operative variables collected included age, sex, body mass index (BMI), pre-operative creatinine and preoperative stent placement. Stone characteristics collected included laterality, location, stone burden (measured in grams), and stone density (measured in Hounsefield units - HU). Operative characteristics included in the analysis were operative time, ureteroscopy time, estimated blood loss (EBL), use of basketing, and intra-operative stenting. Safety and post-operative data collected included duration of admission after surgery, post-operative creatinine, change in creatinine after surgery, incidence of post-operative complication (graded on the Clavien-Dindo scale [8]), incidence of ureteral injury, need for post-operative transfusion, number of repeat procedures (if any), and SFR at one month.

Study Outcomes:

The primary outcome measured was SFR at one month. This was defined as either no apparent residual stone fragments, or the presence of fragments ≤ 2 mm on postoperative CT. Other key secondary outcomes included the operative and ureteroscopy time, number of repeat procedures, need for basketing, duration of hospital stay, the incidence of ureteral injury and incidence of any postoperative complications.

Statistical Analysis:

For continuous variables, means with standard deviation were measured to assess central tendency, while categorical variables were reported as absolute numbers and percentages. Univariate logistic regression was performed using relevant perioperative variables, following which a multivariate model was created using those variables that demonstrated statistical significance. Odds ratios with 95% confidence intervals were generated for the relevant variables. All analysis was performed on R programming software version 4.3.3.

Patient Characteristics [Table 1]

Table 1

BASELINE CHARACTERISTICS
PARAMETER	RESULT
Number of patients, n	2284
Sex, n (%): Male Female	1252 (54.8%) 1032 (45.2%)
Age, mean ± SD	48 ± 14.5
Body Mass Index, mean ± SD	29.8 ± 6.04
Pre-operative Creatinine (mg/dL), mean ± SD	1.15 ± 0.35
Preoperative Stent Placed, n (%)	1135 (49.7%)

In total, 2284 patients underwent URS for the treatment of upper tract stone disease. 54.8% of the group was male, while 45.2% were female. The mean age of the group was 48 ± 14.5, with a mean BMI of 29.8 ± 6.04. The mean preoperative creatinine was 1.15 ± 0.35 mg/dL. Half of all patients underwent preoperative stent placement prior to URS.

Stone Characteristics [Table 2]

Table 2

STONE CHARACTERISTICS
PARAMETER	RESULT
Laterality, n (%): Right Left	1213 (53.1%) 1071 (46.9%)
Stone Location, n (%): Upper Pole and Pelvis Lower Pole	1844 (80.7%) 440 (19.3%)
Stone Burden (grams), mean ± SD	0.92 ± 0.37
Stone Density, Hounsefield Units (HU), n(%): < 600 600–950 > 950	968 (42.4%) 1123 (49.2%) 193 (8.4%)

Stone disease affected each side (right and left) in roughly equal proportions. 20% of stones were in the lower pole. The mean stone burden was 0.92 ± 0.37 grams; on preoperative imaging, 42.4% of stones were of low density, while 49% and 8.4% were of intermediate and high density, respectively.

Operative Characteristics [Table 3]

Table 3

OPERATIVE CHARACTERISTICS
PARAMETER	RESULT
Operative time (minutes), mean ± SD	95.91 ± 45.2
Ureteroscopy time (minutes), mean ± SD	66.7 ± 21.4
Estimated Blood Loss (ml), mean ± SD	49.9 ± 79.8
Use of basket intraoperatively, n (%):	249 (10.9%)
Intraoperative stent placement, n (%):	1566 (68.6%)
Post-operative Stay, n (%): ≤ 1 day > 1 day	207 (9.1%) 2077 (90.9%)

The mean operative time was 95.91 ± 45.2 minutes while the mean ureteroscopy time was 66.7 ± 21.4 minutes. The mean EBL was noted to be 49.9 ± 79.8 ml. Despite the use of the suction clearance, basketing was required in 11% of patients. Approximately 70% of patients underwent intraoperative stent placement. Almost all patients required more than one day of hospital stay after surgery.

Safety and Complication Data [Table 4]

Table 4

SAFETY AND COMPLICATION DATA
PARAMETER	RESULT
Post-operative Creatinine, mean ± SD	1.24 ± 0.34
Change in Creatinine (gm/dL), mean ± SD (postoperative – preoperative)	0.09 ± 0.49
Total Number of Post-operative Complications, n (%)	221 (9.6%)
Postoperative Fever, n (%)	105 (4.6%)
Postoperative Sepsis, n (%)	32 (1.4%)
Ureteral Injury, n (%):	34 (1.48%)
Need for post-operative transfusion, n (%)	13 (0.56%)
Post-operative Complications within 90 days, n (%): Clavien-Dindo 1 Clavien-Dindo 2 Clavien-Dindo 3 Clavien-Dindo 4	118 (5.2%) 74 (3.1%) 27 (1.2%) 2 (0.08%)
Number of repeat procedures, n (%): 0 1 2 3 ≥ 4	1154 (50.5%) 800 (35%) 287 (12.6%) 26 (1.2%) 17 (0.7%)
Stone Free Rate at one month, n (%)	1960 (85.81%)

The mean postoperative creatinine of the group was 1.24 ± 0.34 while the mean change in creatinine after surgery was noted to be 0.09 ± 0.49 (postoperative-preoperative). Overall, 9.6% of patients experienced a complication after surgery. Ureteral injury was seen in 1.5% of patients. Clavien-Dindo complication ≥ 3 was seen in 1.28% of patients. In terms of infectious complications, 4.6% of patients experienced fever after surgery, while 1.4% experienced sepsis requiring systemic antibiotics. Overall, 50% of all patients did not require a repeat procedure for stone clearance, while 35% of patients required one repeat procedure for stone clearance. Seventeen patients (0.7%) required four or more procedures for stone clearance. These 17 patients were not stone free at one month. At one month of follow-up, the SFR was 86%.

Predictors of stone-free rate at one month [Table 5]

Table 5

UNIVARIATE AN MULTIVARIATE ANALYSIS OF PERIOPERATIVE FACTORS INFLUENCING STONE FREE RATE AT ONE MONTH
PARAMETER	UNIVARIABLE			MULTIVARIABLE
PARAMETER	Stone Free at 1 month	Residual Stone Disease at 1 month	p value	Odds Ratio (95% CI)	p value
Age, mean ± SD	47.1 ± 14.6	53.3 ± 13.1	< 0.001	0.97 (0.96–0.98)	< 0.001
BMI, mean ± SD	29.9 ± 6.04	29.7 ± 6.05	0.75
Sex: Male Female	1069 (46.8%) 891 (39%)	183 (8%) 141 (6.2%)	0.52
Preoperative Creatinine, mean ± SD	1.15 ± 0.36	1.16 ± 0.25	0.6
Preoperative Stent Placed, n (%)	969 (42.4%)	166 (7.3%)	0.55
Stone Burden, mean ± SD	0.906 ± 0.36	1.02 ± 0.39	< 0.001	0.45 (0.33–0.62)	< 0.001
Stone Density, HU: < 600 600–950 > 950	830 (36.3%) 956 (41.9%) 174 (7.6%)	138 (6%) 167 (7.3%) 19 (0.8%)	Reference 0.69 0.1
Procedure Time, mean ± SD	66.8 ± 21.4	66 ± 21.5	0.53
Estimated Blood Loss, mean ± SD	49.9 ± 79	50.45 ± 84.6	0.91
Use of basket:	227 (9.9%)	22 (0.9%)	0.01	2.17 (1.33–3.53)	0.002
Intraoperative Stent Placed:	1320 (57.8%)	246 (10.8%)	0.002	0.71 (0.54–0.95)	0.02
Postoperative Creatinine, mean ± SD	1.23 ± 0.34	1.26 ± 0.38	0.37
Change in creatinine (preoperative - postoperative), mean ± SD	0.1 ± 0.5	0.06 ± 0.45	0.38
Ureteral Injury:	30 (1.3%)	4 (0.2%)	0.68

Univariate logistic regression analysis yielded age, stone burden, use of basket intraoperatively, and intraoperative stent placement as being associated with SFR. On multivariate analysis, age (OR 0.97 [0.96–0.98]), stone burden (OR 0.45 [0.33–0.62]), and intraoperative stent placement (OR 0.71 [0.54–0.95]) were inversely associated with SFR, while the use of basket intraoperatively (OR 2.17 [1.33–3.53]) was directly associated with SFR. The association for age, however, was small, with the odds ratio trending towards one.

This study demonstrated that in 2284 patients, SES URS led to a one-month SFR of 85.8% overall. To our knowledge, this is the largest continuous series of patients in the literature to undergo SES URS. On multivariate analysis, intraoperative basketing was associated with higher odds of achieving stone-free status. Conversely, increased age, higher stone burden, and the placement of a stent after the procedure were associated with lower odds of achieving stone-free status. Though age was a statistically significant predictor, the odds ratio trended to zero, thus hinting that this association may not be of clinical relevance. Studies have previously shown SFR to be comparable between younger and older patients [9].

An increase in stone burden meant higher volume of disease, which is a known risk factor for residual disease. In cases where the surgeon was not confident about complete stone clearance, a stent was placed to aid in collecting system drainage. This may explain the association that was found between stent placement and SFR. Intraoperative basketing was associated with a higher SFR. From this, it may be reasonable to conclude that the use of SES does not ensure complete stone clearance during URS and thus, may require further basketing/dusting. Surgeons who perform SES URS must be aware of the need for further manual stone clearance if necessary; this is a decision that must be made intraoperatively. The primary use of SES URS may be only to decrease operative time and infectious complications.

High IRP during URS may promote the translocation of bacteria into the bloodstream, causing life-threatening urosepsis [10]. The continuous suction evacuation of fluid and fragments by the SES decreases IRP, resulting in a lower incidence of infectious complications after URS [11]. In this study, we found a 4.6% incidence of fever and 1.4% incidence of sepsis after SES URS, which is in line with prior findings [12]. In a systematic review of traditional URS, sepsis rates ranged from 0.5%-11.1% [13]. We noted an overall complication rate of 9.6%, with more than half of those being Clavien-Dindo 1. Only 1.28% of patients experienced a major complication (Clavien-Dindo ≥ 3), thus demonstrating the safety of SES URS for renal and ureteric stone treatment. Similar complication rates have been noted in previous studies that have explored the outcomes of vacuum-suction devices [14–16].

The use of SES has been increasing due to shorter operating times, convenient instrumentation, and a lower incidence of postoperative infectious complications. The use of SES (ClearPetra) in PCNL has been studied well, with one randomized controlled trial (RCT) demonstrating shorter operative times and comparable stone free rates with the use of the suction device [17]. On the other hand, fewer prospective studies in SES URS have been carried out to date, and this remains a relatively unexplored area in the literature. An RCT assessing Kidney Injury Molecule-1 (KIM-1) levels after URS and found that the use of SES was associated with lower KIM-1 levels when compared to URS without the use of an access sheath [18]. In addition to single arm studies, few reports have analyzed the outcomes of SES URS in comparison to traditional URS. In a matched analysis of 330 patients, the authors found significantly lower infectious complication rate in the SES group, along with shorter operative time, and higher early SFR [19]. Another retrospective study examining the differences between traditional sheaths and SES found that patients with predictable risk factors for infections could benefit from the use of SES [20]. The current study corroborates these earlier findings, as we found similar SFR and complication rates. Further RCTs are required to truly ascertain the differences between conventional URS and SES URS.

This study is not without limitations. Firstly, the retrospective nature of our study may have introduced bias into our analysis. Additionally, this was a single arm study that did not have a matched group for comparison. Finally, we did not measure IRP due to a lack of instrumentation. To compensate for this, we measured the rates of postoperative infectious complications (fever and sepsis) and postoperative renal damage (creatinine), which are both consequences of increased IRP. We found low rates of infectious complications (as outlined above), and very little difference between preoperative and postoperative creatinine (thus implying little or no renal damage).

Despite these limitations, we believe this study is valuable as it represents the largest continuous series of patients to undergo SES URS for renal stone disease and highlights the potential need for continued manual extraction with basketing during SES URS, while providing evidence of the safety of this procedure.

SES URS can be safely performed in patients with renal stone disease, with low rates of postoperative complications. SES URS may decrease operative time and infectious complications. The increase in SFR when performing basketing may suggest that manual extraction of fragments may still be necessary during SES URS.

Conflicts of Interest: The authors have no relevant financial or non-financial interests to disclose.

Ethics Approval: In view of the retrospective nature of the study, the IRB waived the need for ethics approval as all the procedures were performed as part of the routine patient care.

Consent: Informed consent was obtained for data collection and usage from patients involved in the study. The study was approved by the local institutional review board (IRB # ITCBM44678/12012).

Data availability: Data has not been stored in a repository due to local institutional policies. Details regarding the data are available from the authors on reasonable request.

Author Contributions: Conceptualization: Maurizio Buscarini; Data collection: Maurizio Buscarini; Formal analysis: Kaushik Prabhav Kolanukuduru, Asher Mandel; Writing – original draft: Kaushik Prabhav Kolanukuduru, Asher Mandel; Writing – review and editing: Neeraja Tillu, Osama Zaytoun, Zachary Dovey; Supervision: Maurizio Buscarini

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No competing interests reported.

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Version 1

posted

You are reading this latest preprint version

Exploring the use of suction evacuation sheath for surgical treatment of renal stones during ureteroscopy: An analysis of 2284 cases

Status:

Version 1

Abstract

Introduction

Methods

Study setting, design and participants:

Procedure Details and Postoperative Assessments:

Data variables:

Study Outcomes:

Statistical Analysis:

Results

Patient Characteristics [Table 1]

Stone Characteristics [Table 2]

Operative Characteristics [Table 3]

Safety and Complication Data [Table 4]

Predictors of stone-free rate at one month [Table 5]

Discussion

Conclusion

Declarations

References

Additional Declarations

Status:

Version 1