The Use of Self-Retaining Barbed Suture for InnerLayer Renorrhaphy Significantly Reduces Warm

Ischemia Time in Laparoscopic Partial Nephrectomy:Outcomes of a Matched-Pair Analysis

Selcuk Erdem, MD, Tzevat Tefik, MD, FEBU, Anar Mammadov, MD, Feyyaz Ural, MD,Tayfun Oktar, MD, FEBU, Halim Issever, MD, Ismet Nane, MD, and Oner Sanli, MD, FEBU

Abstract

Purpose: To investigate the efficacy of self-retaining barbed suture (SRBS) on reducing renorrhaphy time andwarm ischemia time (WIT) during laparoscopic partial nephrectomy (LPN), in comparison with conventionalpolyglactin suture.Patients and Methods: Between February 2008 and June 2012, 115 patients underwent LPN for renal tumors atour 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 in-stitutional laparoscopic database (unmatched comparison). Furthermore, 17 patients from each group werematched at a 1:1 ratio in terms of sex, age, body mass index, preoperative aspects and dimensions used foran anatomic (PADUA) classification scoring system, and operative approach (transperitoneoscopic/retroperitoneoscopic) to eliminate the effects of these variables on WIT (matched-pair comparison). Demo-graphic, perioperative, and pathologic parameters were evaluated between groups in both unmatched andmatched-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 twogroups in the unmatched comparison. Median PADUA score (9 vs 8, P = 0.006), median preoperative (4 cm vs3.6 cm, P = 0.049), and pathologic (4.5 cm vs 3.5 cm, P = 0.009) tumor size, however, were significantly higher ingroup 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 ofmedian PADUA score (8 vs 8, P = 1), median preoperative (3.8 cm vs 4 cm, P = 0.959), and pathologic (4.2 cm vs4 cm, P = 0.284) tumor size.Conclusions: The SRBS significantly reduced inner layer renorrhaphy time and WIT during LPN and may enableurologists to perform LPN in more challenging and larger tumors, in comparison with conventional polyglactinsuture.

Introduction

Partial nephrectomy (PN), with its advantage of neph-ron sparing and favorable oncologic outcomes, is ac-

cepted as the standard of care for small, localized renalmasses (<4 cm) and offers increased overall survival rateswith similar oncologic results compared with radical ne-phrectomy.1,2 Recently, it has been recommended thaturologists should exert an effort to perform PN in all tech-nically feasible and amenable patients with renal tumors up

to 7 cm in diameter. The indications and patient selectionhave been well described in guidelines published by theAmerican Urological Association and the European Asso-ciation of Urology.3,4

Several factors have been described to predict renal func-tion after PN. Among them, warm ischemia time (WIT) is theonly modifiable predictor and is dependent on the surgeonand surgical technique.5 This time-dependent predictivefactor can be improved through surgical and technologicalinnovations.

Department of Urology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey.

JOURNAL OF ENDOUROLOGYVolume 27, Number 4, April 2013ª Mary Ann Liebert, Inc.Pp. 452–458DOI: 10.1089/end.2012.0574

452

Since the first description of the method, laparoscopicpartial nephrectomy (LPN) has been performed in experi-enced centers with a constant evolution and refinement of thetechnical details.6 Intracorporeal suturing for hemostasis,renal parenchymal repair, or closure of the pelvicalicealsystem under the constraint of warm ischemia is the mosttechnically challenging and time-consuming step of LPN andneeds to be improved during the learning curve of operation.

Different methods, including hemostatic agents or energy-based technologies, have been proposed to obtain fasterhemostasis and renal parenchymal repair under warmischemia.7,8 These methods, however, have remained assupportive of intracorporeal parenchymal suturing, whichhas been accepted as the most safe and suitable surgicaltechnique.9 Hence, different suturing techniques have alsobeen proposed for parenchymal repair or for closure of thecollecting system to reduce WIT.10–12

Recently, a new generation of absorbable, self-retainingbarbed suture (SRBS) has been used for renal parenchymal orpelvicaliceal repair to reduce WIT during LPN.13–16 With a‘‘self-cinching mechanism’’ described by Olweny and associ-ates,14 SRBS do not need traction with the nondominant handor insertion in an extra port, tying a knot, and clips for se-curing each suture. Thus, decreased WIT during LPN can beachieved by faster hemostasis or parenchymal repair with thissuture.

The present study aimed to compare the perioperativeoutcomes of LPN when SRBS or conventional multifilamentpolyglactin suture was used for inner layer renorrhaphy.Furthermore, the efficacy of the new generation SRBS on re-ducing WIT was investigated by a matched-pair analysis incomparison with polyglactin sutures.

Patients and Methods

Patient selection

Between February 2008 and June 2012, 115 patients un-derwent LPN for suspected renal masses observed in radio-logic evaluation. The patients were retrospectively identifiedaccording to the technique of inner layer renorrhaphy (innerlayer repair of remnant renal parenchyma after excision of thetumor).

In 87 cases, ligation of the vessels in the deep layer andpelvicaliceal 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 poly-glyconate 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 forthis study as group 1 and 2, respectively. After the exclusion of11 patients (3 from the V-Loc group and 8 from the Vicrylgroup) whose operations were performed without warm is-chemia and 10 patients whose inner layer repair was coagu-lated with an argon beam before suturing, 33 patients fromeach group were included in the study. The prospectivelycollected demographic, operative, and pathologic outcomeswere retrospectively compared between groups (unmatchedanalysis).

Furthermore, 17 patients from each group were matched ata 1:1 ratio with respect to sex, age (within 5 years), body massindex (BMI) (maximum range of 3 kg/m2 in the same WorldHealth Organization-BMI classification), preoperative aspects

and dimensions used for an anatomic (PADUA) classificationscoring system, and operative approach (transperitoneo-scopic or retroperitoneoscopic) to eliminate the effects of thesevariables on WIT. PADUA scores were prospectively calcu-lated for the tumors in patients who underwent LPN based onthe original definition of the classification by Ficarra and co-workers.17 et al. On the other hand, the tumors that occurredbefore the report of Ficarra and associates17 were retrospec-tively scored using preoperative radiologic imagings. Theprospectively collected demographic, perioperative, andpathologic outcomes were retrospectively compared betweenthe two suturing techniques (matched-pair analysis).

The suturing time of the inner layer remnant parenchyma,WIT, and operative time (OT) were determined from thedigitally recorded operative video database. Functional renalpreservation was assessed through the comparison of pre-operative and early postoperative estimated glomerular fil-tration rate (eGFR), which was calculated using the ChronicKidney Disease Epidemiology Collaboration formula (http://www.kidney.org/professionals/kdoqi/gfr_calculator.cfm).The early postoperative eGFR was based on a serum creati-nine (sCr) measurement obtained after the peak sCr withinthe first 3 days of surgery, which has been shown to be asignificant predictor of the future function of the preservedkidney.5 The differences between the preoperative and earlypostoperative eGFRs, described as deGFR, were also com-pared between the groups to investigate the nephron-sparingefficacy.

Surgical technique

Our previously described LPN technique includes trans-peritoneoscopic or retroperitoneoscopic exposure of the kid-ney, renal hilar dissection, identification of the tumor, warmischemia application with bulldog or Satinsky clamping, andexcision of the tumor with cold scissors in a safety marginscored with an electrocauterizing J-hook.18 After the resectionof the tumor, intracorporeal suturing with 3-0 polyglyconateSRBS or 3-0 polyglactin sutures was used to repair the innerlayer of the renal parenchyma for hemostasis and to closethe pelvicaliceal system, if needed. The edges of the renalremnant (outer layer) were approximated using 0 absorb-able polyglactin sutures secured with Hem-o-lok� clips(Weck Closure Systems, Research Triangle Park, NC) afterinner layer renorrhaphy. To ensure adequate hemostasis, theoperative field was observed under 4 mm Hg pneumoper-itoneum after unclamping the vessels, and the tumor wasremoved within a laparoscopic organ bag (EndoCatch ITM

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 needlewas passed through the looped end after running through thetransected blood vessels or collecting system at the initialtissue bite. Tension was created by pulling the suture with thenondominant hand only once, and the suture line maintainedits tautness without needing to be repulled or held. Two finalneedle throws were made after closing all transected collect-ing systems and controlling all transected blood vessels tomaintain the tautness created by the previous stitches. Thismaneuver eliminated the need for additional anchoring clipsand contributed to the cost-effectiveness of the procedure. Theouter parenchymal layer was repaired with 0 polyglactin

BARBED SUTURE IN LPN 453

sutures using the sliding clip renorrhaphy technique that waspreviously described by Benway and colleagues.12 Oxidizedcellulose 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 tissuebite, a knot was needed to secure the suture on the tumor bed.The transected collecting system and blood vessels were closedwith running sutures, and tension on the suture line wasmaintained by pulling the suture using the nondominant handor by an additional instrument used for assistance via a pre-viously placed port. After the final tissue bite, a knot was ap-plied 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 meanand standard deviation, whereas ordinals or variables notfitting normal distributions are reported as the median andrange. 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 testwere used when appropriate to compare continuous andcategorical variables. For all statistical analyses, a two-sidedP < 0.05 was considered statistically significant.

Results

The comparative outcomes of the unmatched analysis arelisted in Table 1. There was no statistically significant differ-ence in demographics between the two groups except for theincreased median PADUA score (9 vs 8, P = 0.006) and pre-operative tumor size (40 mm vs 36 mm, P = 0.049) in the SRBSgroup. The perioperative outcomes, including OT, estimatedblood loss (EBL), hospital length of stay (LOS), complicationsand preoperative and postoperative laboratory analyses weresimilar between the two groups.

The median inner layer parenchymal suturing time(P = 0.099) and the median WIT (P = 0.067), however, were notsignificantly but notably lower in the SRBS group, compared

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

Pathology report (n, %) 0.138RCC 25, 75.8 30, 90.9Oncocytoma 5, 15.2 3, 9.1Angiomyolipoma 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 foran anatomic; Hgb = hemoglobin; Hct = hematocrit; eGFR = estimated glomerular filtration rate; RCC = renal-cell carcinoma.

454 ERDEM ET AL.

with the polyglactin suture group. The median pathologictumor size (4.5 cm vs 3.5 cm, P = 0.009) was significantly in-creased in the SRBS group, while no difference was observedwith respect to tumor pathology and surgical margin posi-tivity between the two groups.

To eliminate patient- and tumor-related predictors of theoperative challenge, the outcomes were further compared in amatched-pair (sex, age, BMI, PADUA score, and operativeapproach) analysis, which is described in Table 2. As ex-pected, no patient- or tumor-related demographic differenceswere noted between the two groups. The median suturingtime (350 sec vs 505 sec, P = 0.004) and the median WIT (19 minvs 28 min, P = 0.037) were both statistically significant in favorof the SRBS group. This significance was not reflected in themedian OT, and no other perioperative difference was de-termined in terms of EBL, LOS, and complications. The tumorpathology, size, and surgical margin positivity were all sim-ilar between the matched groups.

In both the unmatched and matched analysis, the medianpreoperative and postoperative eGFR were not different

between the groups. On the other hand, the median deGFRtended 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 matchedanalysis (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 notsignificant.

The intraoperative and postoperative complications arelisted in Table 3. In each matched group, three minor post-operative complications occurred. These complications wereone case of fever, one blood transfusion, and one elongateddrainage in the SRBS group and two cases of fever and oneileus controlled with nasogastric decompression in the poly-glactin suture group.

Discussion

PN is accepted as the standard of care for clinical T1 renaltumors in all amenable patients, either by an open, laparo-scopic, or a robot-assisted technique.3,4 Although the renal-cell carcinoma (RCC) guidelines still recommend open partial

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

Pathology report (n, %) 0.168RCC 12, 70.6 16, 94.1Oncocytoma 3, 17.6 1, 5.9Angiomyolipoma 2, 11.8 0, 0

Positive surgical margin (n, %) 1, 5.9 1, 5.9 1

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

BARBED SUTURE IN LPN 455

nephrectomy (OPN) as the gold standard of treatment, LPNhas been performed with similar oncologic and functionaloutcomes as a minimally invasive alternative to OPN in ex-perienced centers.19,20 The increased experience has allowedurologists to expand the indications for LPN in parallel withnephron-sparing recommendations.21,22

On the other hand, the role of WIT on nephron sparing hasbeen one of the most discussed issues in PN. In their large PNseries with 1169 patients, Lane and coworkers5 classified theindependent predictors of postoperative and long-term eGFRafter PN as patient-specific (older age, male sex, preoperativeeGFR, and solitary kidney or non-functional contralateralkidney), tumor-specific (large tumor size and interpolar lo-calization), and surgical (WIT) factors. Among these inde-pendent factors, WIT was the only modifiable predictor ofrenal function after PN. In addition, the WIT in LPN wasfound longer than in OPN.23,24 In the study comparing 771LPNs and 1028 OPNs, Gill and colleagues25 reported that themean WIT in LPN was approximately 10 minutes (1.69 times,P = 0.001) longer than in OPN. Although Godoy and co-workers26 demonstrated the safety of an increased WIT, lon-ger than 30 minutes and up to 40 minutes, on earlypostoperative deGFR (the difference between postoperativeand preoperative GFR) for LPN, reducing WIT is a widelyaccepted conception for laparoscopic nephron-sparing sur-gery.26–29 For this reason, laparoscopic urologists should bemotivated to exert every effort to shorten the WIT.

During the continued evolution of LPN, neither hemostaticagents or tissue sealants nor energy-based technologies havesuperseded the intracorporeal suturing technique, which wasfirst reported as a laparoscopic duplication of OPN by Gilland associates.30 These alternate methods were accepted asadjuvant technologies to facilitate and achieve optimal sur-gical outcomes.9 Eliminating knot tying with absorbable clipsor its modifications and the sliding-clip renorrhaphy techniquedescribed in robot-assisted LPN were widely accepted as morecompatible, applicable, and reproducible improvements forsurgery and were introduced into the LPN practice.10–12

With the recent evolution of suture technology, the use ofSRBS has been suggested by different centers. This self-retaining knotless absorbable suture was first used by plastic

surgeons and gynecologists for wound closure during dif-ferent operations.31,32 In the field of urology, the SRBS wasinitially investigated by in vitro experimental and in vivo an-imal studies for ureteropelvic anastomosis in pyeloplasty andvesicourethral anastomosis for radical prostatectomy.33,34 Theuse of SRBS was introduced into the urology practice for ve-sicourethral anastomosis of robot-assisted radical prostatec-tomy.35 Subsequently, the efficacy of this suture on reducinganastomosis and operative time in comparison with tradi-tional monofilament sutures was evidenced by differentcenters.36–38

In a single center experience, Shah and colleagues39 re-ported a wide range of various oncologic and reconstructiveindications for which SRBS were used. The first experience inLPN was reported by Shikanov and associates40 in an ex-perimental animal study. The authors performed bilaterallower pole heminephrectomy in 10 pigs using SRBS in onekidney and polyglactin sutures secured with clips on thecontralateral kidney for the repair of renal parenchyma andthe pelvicaliceal collecting system. They found that there wereno differences between the two suture techniques with respectto WIT, OT, resected tissue weight, and the number of post-operative urine leakages.

The adaptation of this suturing technique for humans un-dergoing LPN with or without robot-assisted technology wasdescribed by Seideman and coworkers.13 In this report, theysuggested that SRBS might help novice laparoscopic urolo-gists to shorten the learning curve of intracorporeal suturingand enable experienced surgeons to reduce WIT. After thisreport, the same group published their experience comparingthe efficacy of SRBS and polyglactin sutures on perioperativeoutcomes in patients undergoing LPN.14 They concluded thatthe use of SRBS during the inner-layer renorrhaphy step sig-nificantly reduced WIT (P = 0.0013) and tended to decreaseclinically significant bleeding necessitating intervention(P = 0.06) compared with the polyglactin sutures.

In their robot-assisted LPN experience with 30 cases (15patients per group), Sammon and associates15 achieved a sig-nificant 25.1% (6.1 min) reduction in the mean WIT (18.5 min vs24.7 min, P = 0.008) with SRBS, compared with polyglactin su-tures. With a limited size of two patients, Garcıa-Segui andcolleagues16 reported the efficacy and feasibility of using SRBSfor hemostasis and for reducing the WIT in LPN.

The current study included two different comparative an-alyses. Comparison of the unmatched groups resulted in nostatistically significant differences between the SRBS andpolyglactin suturing techniques in terms of inner layer pa-renchymal repair time, WIT, or OT. The median operativechallenge according to the PADUA scoring system (9 vs 8,P = 0.006) and the median preoperative tumor size (40 mm vs36 mm, P = 0.049), however, were both significantly increasedin the SRBS group. On the other hand, the previous compar-ative studies that suggested the superiority of SRBS did notreport difference in tumor size between groups with using amatched-pair analysis.14,15

After this finding, we designed a further comparison bymatching the two groups according to several factors (sex,age, BMI, PADUA scoring, and operative approach) andsubsequently eliminating the effects of these factors on oper-ative difficulty. This matched-pair analysis revealed the effi-cacy of SRBS for improved median suturing time (with agained time of 2 minutes and 35 seconds, P = 0.004) and

Table 3. Perioperative Complications in Self-

Retaining Barbed Suture and Polyglactin Suture

SRBSPolyglactin

suture

Fever 2 4Ileus controlled with

nasogastric decompression- 1

Transfusion 2 2Elongated drainage 2 -Bleeding (1300 mL) in recovery

room, laparoscopic exploration,and open nephrectomy

1 -

Bleeding from polar arterycontrolled with intracorporealsuturing and Floseal�

1 -

Increased creatinine levels 1 -Overall 9 7

SRBS = self-retaining barbed suture.

456 ERDEM ET AL.

median WIT (with a decreased time of 9 minutes, P = 0.037)compared with polyglactin suture. Meanwhile, the OT wassimilar between the two groups (P = 0.368).

In our LPN series, we found that the lowest eGFR wasgenerally observed in the early postoperative period (1–3days) during intermediate term follow-up.41 This finding wassimilar with the previous report of Lane and colleagues,5

which indicated that there was a significant predictive valueof early postoperative eGFR on the future function of thepreserved kidney. Thus, we compared the early postoperativeeGFR between the groups and found no significant differencein both the matched and unmatched cohorts. On the otherhand, a notable decrease in the median deGFRof the SRBSgroup (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-termfollow-up studies.

The self-retaining knotless polyglyconate barbed suture,with its unidirectional tiny barbs, allows the surgeon to passthrough tissue in only one direction and prevents the slippagethat usually occurs using the traditional polyglactin sutures.This knotless feature of the suture facilitates tissue approxi-mation and obviates the difficulty of laparoscopic or roboticintracorporeal knot tying. With this suture, there is no need tomaintain suture tension with the nondominant hand or insertan extra port in laparoscopy or bedside assistance in roboticsurgery; consequently, inner layer renorrhaphy under theconstraint of warm ischemia becomes easier. Thus, in thistechnique, we used SRBS only while performing the innerlayer parenchymal repair for transected major vasculatureand the collecting system. We believe that this is the criticalstep of the operation for preventing complications related tothe tumor bed, such as bleeding and urinary leakage.

The effect of case volume on the perioperative parameterscannot be neglected in the LPN experience. The non-randomized and retrospective nature of this study disabled usto exclude the effect of the learning curve on inner parenchymalrepair and WIT, which is a major limitation of the presentstudy. It is worth mentioning that the condensation of SRBS usein more recent cases may explain the 9 minutes difference inWIT, as well as the advantage of SRBS on inner layer renor-rhaphy time. Another limitation was the limited number ofmatched cohorts, which needs to be supported by larger pro-spective series. The matched-pair analysis of the groups andthe comparison of inner layer parenchymal repair time, how-ever, is an original and powerful feature of the present study.

In addition, despite relatively higher laparoscopic/roboticexperience of the other two (University of Texas SouthwesternMedical Center, Dallas, TX, and Henry Ford Hospital, Detroit,MI) institutions of approximately 4 years compared with oursolely laparoscopic experience, the similar comparative re-sults regarding the efficacy of SRBS on reducing WIT revealedthe utility of the suture.

Our findings in the unmatched analysis suggested thatsimilar perioperative outcomes could be achieved with SRBSin more challenging LPN cases. Furthermore, the matched-pair analysis showed that the use of SRBS shortens the innerlayer parenchymal repair time and WIT in equal conditionscompared with conventional polyglactin sutures. With theseresults, we argued that the SRBS provides faster inner layerparenchymal repair and decreased WIT and enables theurologist to excise more difficult and larger tumors when

performing LPN. Consequently, we believe that the previ-ously described features of SRBS has a significant contributionon reducing WIT and may prevent time-dependent renaldamage; however, these findings need to be confirmed with atleast 5 years of long-term follow-up.

Conclusions

This retrospective comparative study showed that theSRBS significantly reduced inner layer renorrhaphy time andWIT during LPN. This suture also may encourage urologiststo perform LPN in more challenging and larger tumors thatmay need longer warm ischemia durations.

Disclosure Statement

No competing financial interests exist.

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Address correspondence to:Selcuk Erdem, MD

Department of UrologyIstanbul University Istanbul Faculty of Medicine

Istanbul 34020Turkey

E-mail: erdemselcuk1@gmail.com

Abbreviations UsedBMI¼ body mass index

eGFR¼ estimated glomerular filtration rateEBL¼ estimated blood lossLPN¼ laparoscopic partial nephrectomyLOS¼ length of stay

OPN¼ open partial nephrectomyOT¼ operative timePN¼partial nephrectomy

PADUA¼preoperative aspects and dimensionsused for an anatomic

sCr¼ serum creatinineSRBS¼ self-retaining barbed sutureWIT¼warm ischemia time

458 ERDEM ET AL.