The Use of Self-Retaining Barbed Suture for Inner Layer Renorrhaphy Significantly Reduces Warm Ischemia Time in Laparoscopic Partial Nephrectomy: Outcomes of a Matched-Pair Analysis

Abstract

Purpose:

To investigate the efficacy of self-retaining barbed suture (SRBS) on reducing renorrhaphy time and warm ischemia time (WIT) during laparoscopic partial nephrectomy (LPN), in comparison with conventional polyglactin suture.

Patients and Methods:

Between February 2008 and June 2012, 115 patients underwent LPN for renal tumors at our institution. Among them, the patients whose inner layer renorrhaphy was performed using SRBS (group 1, n=33) or polyglactin suture (group 2, n=33) were retrospectively identified from prospectively collected institutional laparoscopic database (unmatched comparison). Furthermore, 17 patients from each group were matched at a 1:1 ratio in terms of sex, age, body mass index, preoperative aspects and dimensions used for an anatomic (PADUA) classification scoring system, and operative approach (transperitoneoscopic/retroperitoneoscopic) to eliminate the effects of these variables on WIT (matched-pair comparison). Demographic, perioperative, and pathologic parameters were evaluated between groups in both unmatched and matched-pair comparison.

Results:

The perioperative parameters including inner layer renorrhaphy time, WIT, estimated blood loss, operative time, length of hospital stay, and complication rate were not statistically different between the two groups in the unmatched comparison. Median PADUA score (9 vs 8, P=0.006), median preoperative (4 cm vs 3.6 cm, P=0.049), and pathologic (4.5 cm vs 3.5 cm, P=0.009) tumor size, however, were significantly higher in group 1. In the matched-pair analysis, inner layer renorrhaphy time (350 sec vs 505 sec, P=0.004) and WIT (19 min vs 28 min, P=0.037) were significantly reduced with the use of SRBS in group 1 without a difference of median PADUA score (8 vs 8, P=1), median preoperative (3.8 cm vs 4 cm, P=0.959), and pathologic (4.2 cm vs 4 cm, P=0.284) tumor size.

Conclusions:

The SRBS significantly reduced inner layer renorrhaphy time and WIT during LPN and may enable urologists to perform LPN in more challenging and larger tumors, in comparison with conventional polyglactin suture.

Introduction

P artial nephrectomy (PN), with its advantage of nephron sparing and favorable oncologic outcomes, is accepted as the standard of care for small, localized renal masses (<4 cm) and offers increased overall survival rates with similar oncologic results compared with radical nephrectomy.^1,2 Recently, it has been recommended that urologists should exert an effort to perform PN in all technically feasible and amenable patients with renal tumors up to 7 cm in diameter. The indications and patient selection have been well described in guidelines published by the American Urological Association and the European Association of Urology.^3,4

Several factors have been described to predict renal function after PN. Among them, warm ischemia time (WIT) is the only modifiable predictor and is dependent on the surgeon and surgical technique.⁵ This time-dependent predictive factor can be improved through surgical and technological innovations.

Since the first description of the method, laparoscopic partial nephrectomy (LPN) has been performed in experienced centers with a constant evolution and refinement of the technical details.⁶ Intracorporeal suturing for hemostasis, renal parenchymal repair, or closure of the pelvicaliceal system under the constraint of warm ischemia is the most technically challenging and time-consuming step of LPN and needs to be improved during the learning curve of operation.

Different methods, including hemostatic agents or energy-based technologies, have been proposed to obtain faster hemostasis and renal parenchymal repair under warm ischemia.^7,8 These methods, however, have remained as supportive of intracorporeal parenchymal suturing, which has been accepted as the most safe and suitable surgical technique.⁹ Hence, different suturing techniques have also been proposed for parenchymal repair or for closure of the collecting system to reduce WIT.^10
–12

Recently, a new generation of absorbable, self-retaining barbed suture (SRBS) has been used for renal parenchymal or pelvicaliceal repair to reduce WIT during LPN.^13

–16 With a “self-cinching mechanism” described by Olweny and associates,¹⁴ SRBS do not need traction with the nondominant hand or insertion in an extra port, tying a knot, and clips for securing each suture. Thus, decreased WIT during LPN can be achieved by faster hemostasis or parenchymal repair with this suture.

The present study aimed to compare the perioperative outcomes of LPN when SRBS or conventional multifilament polyglactin suture was used for inner layer renorrhaphy. Furthermore, the efficacy of the new generation SRBS on reducing WIT was investigated by a matched-pair analysis in comparison with polyglactin sutures.

Patients and Methods

Patient selection

Between February 2008 and June 2012, 115 patients underwent LPN for suspected renal masses observed in radiologic evaluation. The patients were retrospectively identified according to the technique of inner layer renorrhaphy (inner layer repair of remnant renal parenchyma after excision of the tumor).

In 87 cases, ligation of the vessels in the deep layer and pelvicaliceal closures (if needed) were performed by suturing, while 28 renal beds did not need suturing for hemostasis. Among the 87 LPNs, the cases repaired with either 3-0 polyglyconate SRBS (V-Loc™ 180, Covidien, Mansfield, MA) (n=36) or 3-0 polyglactin 910 suture (Vicryl,™ Ethicon, Johnson & Johnson, Somerville, NJ) (n=51) were selected for this study as group 1 and 2, respectively. After the exclusion of 11 patients (3 from the V-Loc group and 8 from the Vicryl group) whose operations were performed without warm ischemia and 10 patients whose inner layer repair was coagulated with an argon beam before suturing, 33 patients from each group were included in the study. The prospectively collected demographic, operative, and pathologic outcomes were retrospectively compared between groups (unmatched analysis).

Furthermore, 17 patients from each group were matched at a 1:1 ratio with respect to sex, age (within 5 years), body mass index (BMI) (maximum range of 3 kg/m² in the same World Health Organization-BMI classification), preoperative aspects and dimensions used for an anatomic (PADUA) classification scoring system, and operative approach (transperitoneoscopic or retroperitoneoscopic) to eliminate the effects of these variables on WIT. PADUA scores were prospectively calculated for the tumors in patients who underwent LPN based on the original definition of the classification by Ficarra and coworkers.¹⁷ et al. On the other hand, the tumors that occurred before the report of Ficarra and associates¹⁷ were retrospectively scored using preoperative radiologic imagings. The prospectively collected demographic, perioperative, and pathologic outcomes were retrospectively compared between the two suturing techniques (matched-pair analysis).

The suturing time of the inner layer remnant parenchyma, WIT, and operative time (OT) were determined from the digitally recorded operative video database. Functional renal preservation was assessed through the comparison of preoperative and early postoperative estimated glomerular filtration rate (eGFR), which was calculated using the Chronic Kidney Disease Epidemiology Collaboration formula (http://www.kidney.org/professionals/kdoqi/gfr_calculator.cfm). The early postoperative eGFR was based on a serum creatinine (sCr) measurement obtained after the peak sCr within the first 3 days of surgery, which has been shown to be a significant predictor of the future function of the preserved kidney.⁵ The differences between the preoperative and early postoperative eGFRs, described as δeGFR, were also compared between the groups to investigate the nephron-sparing efficacy.

Surgical technique

Our previously described LPN technique includes transperitoneoscopic or retroperitoneoscopic exposure of the kidney, renal hilar dissection, identification of the tumor, warm ischemia application with bulldog or Satinsky clamping, and excision of the tumor with cold scissors in a safety margin scored with an electrocauterizing J-hook.¹⁸ After the resection of the tumor, intracorporeal suturing with 3-0 polyglyconate SRBS or 3-0 polyglactin sutures was used to repair the inner layer of the renal parenchyma for hemostasis and to close the pelvicaliceal system, if needed. The edges of the renal remnant (outer layer) were approximated using 0 absorbable polyglactin sutures secured with Hem-o-lok^® clips (Weck Closure Systems, Research Triangle Park, NC) after inner layer renorrhaphy. To ensure adequate hemostasis, the operative field was observed under 4 mm Hg pneumoperitoneum after unclamping the vessels, and the tumor was removed within a laparoscopic organ bag (EndoCatch I^™ bag, Covidien, Norwalk, CT).

In group 1, the inner layer parenchyma was repaired using only a single running 3-0 SRBS and 26-mm needle. The needle was passed through the looped end after running through the transected blood vessels or collecting system at the initial tissue bite. Tension was created by pulling the suture with the nondominant hand only once, and the suture line maintained its tautness without needing to be repulled or held. Two final needle throws were made after closing all transected collecting systems and controlling all transected blood vessels to maintain the tautness created by the previous stitches. This maneuver eliminated the need for additional anchoring clips and contributed to the cost-effectiveness of the procedure. The outer parenchymal layer was repaired with 0 polyglactin sutures using the sliding clip renorrhaphy technique that was previously described by Benway and colleagues.¹² Oxidized cellulose bolsters were used when needed.

In group 2, the inner layer parenchyma was repaired with 3-0 polyglactin suture and 26-mm needle. After the first tissue bite, a knot was needed to secure the suture on the tumor bed. The transected collecting system and blood vessels were closed with running sutures, and tension on the suture line was maintained by pulling the suture using the nondominant hand or by an additional instrument used for assistance via a previously placed port. After the final tissue bite, a knot was applied to preserve the tautness of the suture created previously. The outer parenchymal layer was repaired as described above.

Statistical analysis

Parametric continuous variables are reported as the mean and standard deviation, whereas ordinals or variables not fitting normal distributions are reported as the median and range. The matched-pair analysis was designed at a 1:1 ratio of the above mentioned factors. The Student t test, the Mann-Whitney U test, Pearson chi-square test, and Fisher exact test were used when appropriate to compare continuous and categorical variables. For all statistical analyses, a two-sided P<0.05 was considered statistically significant.

Results

The comparative outcomes of the unmatched analysis are listed in Table 1. There was no statistically significant difference in demographics between the two groups except for the increased median PADUA score (9 vs 8, P=0.006) and preoperative tumor size (40 mm vs 36 mm, P=0.049) in the SRBS group. The perioperative outcomes, including OT, estimated blood loss (EBL), hospital length of stay (LOS), complications and preoperative and postoperative laboratory analyses were similar between the two groups.

Table 1.

Comparison of Demographic, Perioperative, and Pathologic Outcomes Between Self-Retaining Barbed Suture and Polyglactin Suture in the Unmatched Analysis

	SRBS	Polyglactin suture	P
n	33	33
Sex – Male (n, %)	22, 66.7	26, 78.8	0.269
Age (years)	56 (24–80)	60 (32–79)	0.164
Body mass index (kg/m²)	27.54 (19.53–36.28)	26.12 (21.25–37.52)	0.218
ASA score	2 (1–4)	2 (1–4)	0.973
Diabetes mellitus (n, %)	7, 21.2	9, 27.3	0.566
Hypertension (n, %)	20, 60.6	17, 51.5	0.457
Operative side - right (n, %)	11, 33.3	17, 51.5	0.135
Preoperative tumor size (mm)	40.0 (22–120)	36.0 (18–65)	0.049
PADUA score	9 (6–13)	8 (6–12)	0.006
Preoperative Hgb (mg/dL)	13.5 (8.95–16.0)	13.0 (9.1–16.7)	0.322
Preoperative Hct (%)	40.1 (29.8–48.0)	39.0 (31.0–48.1)	0.465
Preoperative creatinine level (mg/dL)	0.9 (0.5–1.7)	0.8 (0.6–1.1)	0.410
Preoperative eGFR (mL/min/1.73m²)	99.0 (52.0–226.0)	94.0 (59.0–149.0)	0.700
Operative approach – transperitoneoscopic (n, %)	32, 97.0	29, 87.9	0.163
Operative time (min)	110.0 (70–190)	120.0 (70–190)	0.763
Inner layer renorrhaphy time (s)	350 (165–720)	400 (190–1290)	0.099
Warm ischemia time (min)	22.0 (14–50)	25.0 (9–57)	0.067
Estimated blood loss (mL)	100.0 (30.0–400.0)	150.0 (20–1000)	0.303
Removal of drainage catheter (d)	3 (2–5)	2 (2–4)	0.489
Length of hospital stay (d)	3 (2–7)	3 (2–7)	0.961
Postoperative Hgb (mg/dL)	11.5 (7.7–13.3)	11.3 (9.0–14.0)	0.908
Postoperative Hct (%)	34.18 (23.4–39.7)	34.4 (28.0–46.0)	0.827
Hgb drop (mg/dL)	1.8 (−0.65–6.3)	1.9 (−2–4.8)	0.263
Hct drop (%)	4.71 (−1.6–20.1)	5 (−4.5–14.8)	0.349
Postoperative creatinine level (mg/dL)	1.0 (0.6–4.0)	1.0 (0.7–1.5)	0.454
Creatinine increase (mg/dL)	0.1 (−0.3–2.3)	0.1 (−0.3–0.6)	0.306
Postoperative eGFR (mL/min/1.73m²)	93.0 (22.0–189.0)	85.0 (45.0–135.4)	0.404
Postoperative eGFR decrease-δeGFR (mL/min/1.73m²)	7.0 (−34.0–39.3)	10.0 (−32.0–62.0)	0.186
Perioperative complications (n, %)	9, 27.3	7, 21.2	0.566
Pathologic tumor size (cm)	4.5 (2–12)	3.5 (1.5–9)	0.009
Pathology report (n, %)			0.138
RCC	25, 75.8	30, 90.9
Oncocytoma	5, 15.2	3, 9.1
Angiomyolipoma	3, 9.1	0, 0
Positive surgical margin (n, %)	1, 3.0	3, 9.1	0.302

SRBS=self-retaining barbed suture; ASA=American Society of Anesthesiologists; PADUA=preoperative aspects and dimensions used for an anatomic; Hgb=hemoglobin; Hct=hematocrit; eGFR=estimated glomerular filtration rate; RCC=renal-cell carcinoma.

The median inner layer parenchymal suturing time (P=0.099) and the median WIT (P=0.067), however, were not significantly but notably lower in the SRBS group, compared with the polyglactin suture group. The median pathologic tumor size (4.5 cm vs 3.5 cm, P=0.009) was significantly increased in the SRBS group, while no difference was observed with respect to tumor pathology and surgical margin positivity between the two groups.

To eliminate patient- and tumor-related predictors of the operative challenge, the outcomes were further compared in a matched-pair (sex, age, BMI, PADUA score, and operative approach) analysis, which is described in Table 2. As expected, no patient- or tumor-related demographic differences were noted between the two groups. The median suturing time (350 sec vs 505 sec, P=0.004) and the median WIT (19 min vs 28 min, P=0.037) were both statistically significant in favor of the SRBS group. This significance was not reflected in the median OT, and no other perioperative difference was determined in terms of EBL, LOS, and complications. The tumor pathology, size, and surgical margin positivity were all similar between the matched groups.

Table 2.

Comparison of Demographic, Perioperative, and Pathologic Outcomes Between Self-Retaining Barbed Suture and Polyglactin Suture in Matched-Pair Analysis

	SRBS	Polyglactin suture	P
n	17	17
Sex – Male (n, %)	14, 82.4	14, 82.4	1
Age (years)	55 (29–80)	57 (32–78)	0.480
Body mass index (kg/m²)	27.55 (19.53–31.25)	26.64 (21.25–30.43)	0.326
ASA score	2 (1–3)	2 (1–4)	0.231
Diabetes mellitus (n, %)	1, 5.9	2, 11.8	0.545
Hypertension (n, %)	10, 58.8	6, 35.3	0.169
Operative side - right (n, %)	4, 23.5	11, 64.7	0.016
Preoperative tumor size (mm)	38 (22–63)	40 (20–65)	0.959
PADUA score	8 (6–12)	8 (6–12)	1
Preoperative Hgb (mg/dL)	13.2 (8.95–16)	12.6 (10.0–15.6)	0.269
Preoperative Hct (%)	40.1 (29.8–48.0)	38.0 (31.0–47.4)	0.370
Preoperative creatinine level (mg/dL)	0.9 (0.5–1.7)	0.9 (0.6–1.1)	0.637
Preoperative eGFR (mL/min/1.73m²)	91.4 (52.0–226.0)	92 (59.0–138.0)	0.593
Transperitoneoscopic approach (n, %)	16, 94.1	16, 94.1	1
Operative time (min)	110 (90–190)	140 (80–190)	0.368
Inner layer renorrhaphy time (s)	350 (240–720)	505 (270–1290)	0.004
Warm ischemia time (min)	19 (12–50)	28 (10–57)	0.037
Estimated blood loss (mL)	100 (30–400)	140 (20–200)	0.986
Removal of drainage catheter (d)	2 (2–4)	3 (2–3)	0.254
Length of hospital stay (d)	3 (2–5)	3 (2–7)	0.224
Postoperative Hgb (mg/dL)	11.6 (8.9–13.3)	11.4 (10–14)	0.703
Postoperative Hct (%)	34.8 (27.2–39.7)	34.1 (30.0–46.0)	0.666
Hgb drop (mg/dL)	1.8 (−0.65–3.13)	1.0 (−2.0–3.0)	0.115
Hct drop (%)	4.5 (−1.6–11.8)	3.0 (−4.5–8.0)	0.428
Postoperative creatinine level (mg/dl)	1.0 (0.6–4.0)	1.1 (0.7–1.5)	0.314
Creatinine increase (mg/dl)	0 (−0.3–2.3)	0.1 (−0.1–0.6)	0.190
Postopeartive eGFR (mL/min/1.73m²)	82.4 (22–189)	83.0 (51–138)	0.480
Postoperative eGFR decrease-δeGFR (mL/min/1.73m²)	0 (−23.0–39.0)	9.0 (−12–62)	0.176
Perioperative complications (n, %)	3, 17.6	3, 17.6	1
Pathologic tumor size (cm)	4.2 (2.5–6.0)	4.0 (1.8–6.0)	0.284
Pathology report (n, %)			0.168
RCC	12, 70.6	16, 94.1
Oncocytoma	3, 17.6	1, 5.9
Angiomyolipoma	2, 11.8	0, 0
Positive surgical margin (n, %)	1, 5.9	1, 5.9	1

In both the unmatched and matched analysis, the median preoperative and postoperative eGFR were not different between the groups. On the other hand, the median δeGFR tended to be lower in both the unmatched (7.0 mL/min/1.73 m² vs 10.0 mL/min/1.73 m², P=0.186) and matched analysis (0 mL/min/1.73 m² vs 9.0 mL/min/1.73 m², P=0.176) in favor of SRBS group, although this difference was not significant.

The intraoperative and postoperative complications are listed in Table 3. In each matched group, three minor postoperative complications occurred. These complications were one case of fever, one blood transfusion, and one elongated drainage in the SRBS group and two cases of fever and one ileus controlled with nasogastric decompression in the polyglactin suture group.

Table 3.

Perioperative Complications in Self-Retaining Barbed Suture and Polyglactin Suture

	SRBS	Polyglactin suture
Fever	2	4
Ileus controlled with nasogastric decompression	-	1
Transfusion	2	2
Elongated drainage	2	-
Bleeding (1300 mL) in recovery room, laparoscopic exploration, and open nephrectomy	1	-
Bleeding from polar artery controlled with intracorporeal suturing and Floseal®	1	-
Increased creatinine levels	1	-
Overall	9	7

SRBS=self-retaining barbed suture.

Discussion

PN is accepted as the standard of care for clinical T₁ renal tumors in all amenable patients, either by an open, laparoscopic, or a robot-assisted technique.^3,4 Although the renal-cell carcinoma (RCC) guidelines still recommend open partial nephrectomy (OPN) as the gold standard of treatment, LPN has been performed with similar oncologic and functional outcomes as a minimally invasive alternative to OPN in experienced centers.^19,20 The increased experience has allowed urologists to expand the indications for LPN in parallel with nephron-sparing recommendations.^21,22

On the other hand, the role of WIT on nephron sparing has been one of the most discussed issues in PN. In their large PN series with 1169 patients, Lane and coworkers⁵ classified the independent predictors of postoperative and long-term eGFR after PN as patient-specific (older age, male sex, preoperative eGFR, and solitary kidney or non-functional contralateral kidney), tumor-specific (large tumor size and interpolar localization), and surgical (WIT) factors. Among these independent factors, WIT was the only modifiable predictor of renal function after PN. In addition, the WIT in LPN was found longer than in OPN.^23,24 In the study comparing 771 LPNs and 1028 OPNs, Gill and colleagues²⁵ reported that the mean WIT in LPN was approximately 10 minutes (1.69 times, P=0.001) longer than in OPN. Although Godoy and coworkers²⁶ demonstrated the safety of an increased WIT, longer than 30 minutes and up to 40 minutes, on early postoperative δeGFR (the difference between postoperative and preoperative GFR) for LPN, reducing WIT is a widely accepted conception for laparoscopic nephron-sparing surgery.^26

–29 For this reason, laparoscopic urologists should be motivated to exert every effort to shorten the WIT.

During the continued evolution of LPN, neither hemostatic agents or tissue sealants nor energy-based technologies have superseded the intracorporeal suturing technique, which was first reported as a laparoscopic duplication of OPN by Gill and associates.³⁰ These alternate methods were accepted as adjuvant technologies to facilitate and achieve optimal surgical outcomes.⁹ Eliminating knot tying with absorbable clips or its modifications and the sliding-clip renorrhaphy technique described in robot-assisted LPN were widely accepted as more compatible, applicable, and reproducible improvements for surgery and were introduced into the LPN practice.^10
–12

With the recent evolution of suture technology, the use of SRBS has been suggested by different centers. This self-retaining knotless absorbable suture was first used by plastic surgeons and gynecologists for wound closure during different operations.^31,32 In the field of urology, the SRBS was initially investigated by in vitro experimental and in vivo animal studies for ureteropelvic anastomosis in pyeloplasty and vesicourethral anastomosis for radical prostatectomy.^33,34 The use of SRBS was introduced into the urology practice for vesicourethral anastomosis of robot-assisted radical prostatectomy.³⁵ Subsequently, the efficacy of this suture on reducing anastomosis and operative time in comparison with traditional monofilament sutures was evidenced by different centers.^36
–38

In a single center experience, Shah and colleagues³⁹ reported a wide range of various oncologic and reconstructive indications for which SRBS were used. The first experience in LPN was reported by Shikanov and associates⁴⁰ in an experimental animal study. The authors performed bilateral lower pole heminephrectomy in 10 pigs using SRBS in one kidney and polyglactin sutures secured with clips on the contralateral kidney for the repair of renal parenchyma and the pelvicaliceal collecting system. They found that there were no differences between the two suture techniques with respect to WIT, OT, resected tissue weight, and the number of postoperative urine leakages.

The adaptation of this suturing technique for humans undergoing LPN with or without robot-assisted technology was described by Seideman and coworkers.¹³ In this report, they suggested that SRBS might help novice laparoscopic urologists to shorten the learning curve of intracorporeal suturing and enable experienced surgeons to reduce WIT. After this report, the same group published their experience comparing the efficacy of SRBS and polyglactin sutures on perioperative outcomes in patients undergoing LPN.¹⁴ They concluded that the use of SRBS during the inner-layer renorrhaphy step significantly reduced WIT (P=0.0013) and tended to decrease clinically significant bleeding necessitating intervention (P=0.06) compared with the polyglactin sutures.

In their robot-assisted LPN experience with 30 cases (15 patients per group), Sammon and associates¹⁵ achieved a significant 25.1% (6.1 min) reduction in the mean WIT (18.5 min vs 24.7 min, P=0.008) with SRBS, compared with polyglactin sutures. With a limited size of two patients, García-Segui and colleagues¹⁶ reported the efficacy and feasibility of using SRBS for hemostasis and for reducing the WIT in LPN.

The current study included two different comparative analyses. Comparison of the unmatched groups resulted in no statistically significant differences between the SRBS and polyglactin suturing techniques in terms of inner layer parenchymal repair time, WIT, or OT. The median operative challenge according to the PADUA scoring system (9 vs 8, P=0.006) and the median preoperative tumor size (40 mm vs 36 mm, P=0.049), however, were both significantly increased in the SRBS group. On the other hand, the previous comparative studies that suggested the superiority of SRBS did not report difference in tumor size between groups with using a matched-pair analysis.^14,15

After this finding, we designed a further comparison by matching the two groups according to several factors (sex, age, BMI, PADUA scoring, and operative approach) and subsequently eliminating the effects of these factors on operative difficulty. This matched-pair analysis revealed the efficacy of SRBS for improved median suturing time (with a gained time of 2 minutes and 35 seconds, P=0.004) and median WIT (with a decreased time of 9 minutes, P=0.037) compared with polyglactin suture. Meanwhile, the OT was similar between the two groups (P=0.368).

In our LPN series, we found that the lowest eGFR was generally observed in the early postoperative period (1–3 days) during intermediate term follow-up.⁴¹ This finding was similar with the previous report of Lane and colleagues,⁵ which indicated that there was a significant predictive value of early postoperative eGFR on the future function of the preserved kidney. Thus, we compared the early postoperative eGFR between the groups and found no significant difference in both the matched and unmatched cohorts. On the other hand, a notable decrease in the median δeGFRof the SRBS group (0 mL/min/1.73 m² vs 9 mL/min/1.73 m², P=0.176) may predict the nephron-sparing advantage of this suture; however, this finding needs to be confirmed with a long-term follow-up studies.

The self-retaining knotless polyglyconate barbed suture, with its unidirectional tiny barbs, allows the surgeon to pass through tissue in only one direction and prevents the slippage that usually occurs using the traditional polyglactin sutures. This knotless feature of the suture facilitates tissue approximation and obviates the difficulty of laparoscopic or robotic intracorporeal knot tying. With this suture, there is no need to maintain suture tension with the nondominant hand or insert an extra port in laparoscopy or bedside assistance in robotic surgery; consequently, inner layer renorrhaphy under the constraint of warm ischemia becomes easier. Thus, in this technique, we used SRBS only while performing the inner layer parenchymal repair for transected major vasculature and the collecting system. We believe that this is the critical step of the operation for preventing complications related to the tumor bed, such as bleeding and urinary leakage.

The effect of case volume on the perioperative parameters cannot be neglected in the LPN experience. The nonrandomized and retrospective nature of this study disabled us to exclude the effect of the learning curve on inner parenchymal repair and WIT, which is a major limitation of the present study. It is worth mentioning that the condensation of SRBS use in more recent cases may explain the 9 minutes difference in WIT, as well as the advantage of SRBS on inner layer renorrhaphy time. Another limitation was the limited number of matched cohorts, which needs to be supported by larger prospective series. The matched-pair analysis of the groups and the comparison of inner layer parenchymal repair time, however, is an original and powerful feature of the present study.

In addition, despite relatively higher laparoscopic/robotic experience of the other two (University of Texas Southwestern Medical Center, Dallas, TX, and Henry Ford Hospital, Detroit, MI) institutions of approximately 4 years compared with our solely laparoscopic experience, the similar comparative results regarding the efficacy of SRBS on reducing WIT revealed the utility of the suture.

Our findings in the unmatched analysis suggested that similar perioperative outcomes could be achieved with SRBS in more challenging LPN cases. Furthermore, the matched-pair analysis showed that the use of SRBS shortens the inner layer parenchymal repair time and WIT in equal conditions compared with conventional polyglactin sutures. With these results, we argued that the SRBS provides faster inner layer parenchymal repair and decreased WIT and enables the urologist to excise more difficult and larger tumors when performing LPN. Consequently, we believe that the previously described features of SRBS has a significant contribution on reducing WIT and may prevent time-dependent renal damage; however, these findings need to be confirmed with at least 5 years of long-term follow-up.

Conclusions

This retrospective comparative study showed that the SRBS significantly reduced inner layer renorrhaphy time and WIT during LPN. This suture also may encourage urologists to perform LPN in more challenging and larger tumors that may need longer warm ischemia durations.

Footnotes

Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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Turkish Association of Urology 22. National Urology Congress.