Self-retaining barbed suture for parenchymal repair during laparoscopic partial nephrectomy; initial clinical experience

Authors


Jeffrey A. Cadeddu, Department of Urology, UT Southwestern Medical Center, 5323 Harry Hines Blvd, J8.106, Dallas, TX 75390-9110, USA. e-mail: Jeffrey.Cadeddu@utsouthwestern.edu

Abstract

Study Type – Therapy (case series)

Level of Evidence 4

What's known on the subject? and What does the study add?

This paper reports on outcomes for SRBS during conventional laparoscopic partial nephrectomy. In addition to an improvement in warm ischaemia time, we found that SRBS use during LPN may be beneficial in reducing rates of clinically significant haemorrhage.

OBJECTIVES

  • • To evaluate the efficacy of a self-retaining barbed suture (SRBS) in achieving a secure and haemostatic renorrhaphy during laparoscopic partial nephrectomy (LPN).
  • • To compare perioperative outcomes for LPN with SRBS with those for LPN with conventional polyglactin suture, with specific attention to warm ischaemia time, blood loss and need for postoperative bleeding interventions.

PATIENTS AND METHODS

  • • Patients who underwent LPN between June 2007 and October 2010 were identified through an Institutional Review Board approved registry of oncological patients.
  • • Before July 2009, parenchymal repair after tumour excision was performed using absorbable polyglactin suture (Group 1), and subsequently, using SRBS (Group 2).
  • • Demographic, clinical, intraoperative and postoperative outcomes were compared for each group.

RESULTS

  • • LPN was performed in 49 patients in Group 1 and 29 in Group 2.
  • • Baseline demographic and clinical features, estimated blood loss, and transfusion and embolization rates were statistically similar for the cohorts.
  • • Mean warm ischaemia time (±SD) was significantly shorter for the SRBS group (26.4 ± 8.3 vs 32.8 ± 7.9; P= 0.0013).
  • • Bleeding requiring intervention (open conversion or transfusion ± embolization) was more common for Group 1 (9/49, 18.4% vs 1/29, 3.4%; P= 0.06).

CONCLUSIONS

  • • The use of SRBS for parenchymal repair during LPN in humans is safe and is associated with a significant reduction in warm ischaemia time.
  • • SRBS use during LPN may also reduce rates of clinically significant bleeding.
  • • Prospective, larger studies to confirm the value of SRBS use in minimally invasive partial nephrectomy are warranted.
Abbreviations
LPN

laparoscopic partial nephrectomy

SRBS

self-retaining barbed suture.

INTRODUCTION

Laparoscopic partial nephrectomy (LPN) was first described in 1993 [1–3], and has since undergone considerable evolution and technical refinement. The primary challenges with maintenance of haemostasis and closure of the collecting system drove the development of a wide range of energy-based technologies for simultaneously sealing transected blood vessels and the renal collecting system. These include tourniquet devices for parenchymal compression during resection, ultrasonic shears, the microwave tissue coagulator, laser devices, electrosurgical snares and radiofrequency-assisted resection among others [4]. In 2002, Gill et al. [5] reported the first clinical experience with LPN wherein techniques for open partial nephrectomy were duplicated, including intracorporeal suturing for repair of the collecting system, oversewing of transected blood vessels, and renorrhaphy. Given the limitations and inconsistency of the energy sealing technologies, the sutured parenchymal repair is now by far the most common LPN technique. However, intracorporeal suturing remains a technically challenging step of LPN, particularly under the time constraint of warm ischaemia.

Contemporary innovations such as the application of the robotic surgical platform to LPN [6], knotless renorrhaphy [7], and sliding clip renorrhaphy [8,9] have contributed to shortening the learning curve and suturing time during LPN. With regard to innovation in suture design, self-retaining barbed suture (SRBS) was recently introduced, initially being applied for wound closure during plastic surgery procedures (Fig. 1) [10]. As this suture is pulled through tissue, the barbs along its shaft deploy and anchor, providing a ‘self-cinching’ mechanism that maintains tension along the suture line and eliminates the need to physically hold the suture or tie knots (Fig. 2). In urology, SRBS has been used clinically for the vesico-urethral anastomosis during robotic-assisted radical prostatectomy, where its use has been reported to decrease anastomotic times, while maintaining integrity of closure [11].

Figure 1.

Self-retaining barbed suture; inset: magnified view of unidirectional barbs along shaft of suture.

Figure 2.

Self-cinching mechanism of self-retaining barbed suture. Suture line tension is maintained by solely by pulling the suture taut.

Preclinical studies evaluating SRBS during porcine LPN have shown equivalent outcomes to conventional absorbable suture with regard to operative time, ischaemia time and integrity of closure [12]. We evaluated the use of SRBS for parenchymal repair during LPN in humans, with the hypothesis that the ‘self-cinching’ mechanism would result in a faster, more haemostatic closure, translating to decreased blood loss, lower transfusion and embolization rates, and decreased warm ischaemia time.

METHODS

Consecutive patients who underwent LPN for tumour by a single surgeon between June 2007 and October 2010 were identified through an Institutional Review Board approved registry of oncological patients. Indication for surgery in all cases was a solid enhancing renal mass by CT or MRI that was worrisome for malignancy. Our standard technique for LPN is described below. In July 2009, we modified this technique by incorporating the V-Loc™ 180 SRBS (Covidien, Mansfield, MA, USA) for the repair of transected major vasculature and collecting system in the tumour bed (inner-layer closure). Patients were divided into two groups based on the type of suture used for the inner-layer closure of the renal defect; in Group 1 the transected vessels and collecting system were oversewn with running 2-0 absorbable polyglactin suture, whereas in Group 2, running 3-0 V-Loc™ SRBS was used. Demographic, clinical (tumour size, location, laterality), and perioperative (procedure time, warm ischaemia time, intraoperative and postoperative complications, hospital length of stay) data were recorded. The groups were compared with regard to the primary outcomes of transfusion rates, use of postoperative angio-embolization and warm ischaemia time. Demographic, clinical and perioperative outcomes were also compared.

The transperitoneal approach was used for all cases. Following abdominal insufflation, a 12-mm peri-umbilical camera port was inserted using the Visiport™ (Covidien) technique. Two additional ports were inserted; a 12-mm port sub-costal in the ipsilateral upper quadrant along the mid-clavicular line, and a 12-mm port in the ipsilateral lower quadrant infero-lateral to the camera port. For right-sided LPN, a 3-mm sub-xiphoid port was placed for insertion of a liver retractor. Medial visceral rotation was completed in the standard fashion. The ureter and renal hilum were mobilized, followed by mobilization of the kidney within Gerota's fascia, care being taken to maintain a cap of peri-nephric fat over the tumour. Location and margins of the tumour were confirmed by intraoperative laparoscopic ultrasonography. Then, 12.5 g mannitol were infused intravenously, followed by en bloc clamping of the renal hilum using a laparoscopic Satinsky clamp introduced through a 12-mm midline suprapubic port. The mass was sharply excised using laparoscopic scissors, placed in a 10-mm Endocatch™ bag (U.S. Surgical Inc., Norwalk, CT, USA), and retained in the abdomen pending completion of parenchymal repair.

In Group 1, one or more 17-cm 2-0 polyglactin sutures on an SH needle and anchored by a Lapra-Ty™ clip (Ethicon, Cincinnati, OH, USA), were used in a running closure of the tumour bed, oversewing transected blood vessels and, where necessary, transected collecting system. Tension on a suture line was maintained by intermittently pulling and holding the suture using the non-dominant hand. Each completed suture line was secured with a Lapra-Ty™ clip at the opposite end. Gelatin/thrombin haemostatic matrix was applied to the resection bed, and renorrhaphy was completed with 0-polyglactin sutures on a CT-1 needle over oxidized cellulose bolsters using the sliding clip technique described by Benway et al. [8]. The Satinsky clamp was removed. If collecting system closure was required, a 19-Fr round drain was positioned within the peri-nephric space and secured.

In Group 2, the inner layer of transected blood vessels and collecting system were repaired using one or more running 3-0 V-Loc™ sutures, each anchored with a single Lapra-Ty™ clip at the tail end. By simply cinching up on the suture after each needle throw, the suture line maintained its tautness without the need for tension management by the non-dominant hand. Additionally, after the final tissue bite, brought out through the renal capsule, the needle was simply retrieved without tying a knot or placing a securing clip. Renorrhaphy was then completed as described above.

Continuous variables were compared using the Student's t test and categorical variables were compared using the chi-squared test. Proportions were compared using the z-test for proportions. A P value ≤0.05 was used to determine statistical significance for all comparisons. Analyses were run using the Stata™ v. 10 statistical software package (StataCorp LP, College Station, TX, USA).

RESULTS

Seventy-eight patients successfully underwent LPN during the study period, 49 in Group 1 (inner layer closed with polyglactin suture) and 29 in Group 2 (inner layer closed with SRBS). The groups were identical with respect to baseline demographic and clinical characteristics including age, gender distribution, body mass index (BMI), American Society of Anesthesiologists (ASA) score, tumour size, laterality and proportion with previous abdominal surgery (Table 1).

Table 1.  Demographics and clinical characteristics
DescriptionGroup 1 (Polyglactin suture)Group 2 (V-Loc™)P value
  1. BMI, body mass index; ASA, American Society of Anesthesiologists.

N4929 
Age (years), mean (sd)55.1 (12.9)55.1 (13.0)0.99
Gender (M/F)27/2213/160.38
BMI, kg/m2, mean (sd)29.9 (6.3)30.4 (6.0)0.69
Median ASA score (range)2.0 (2–4)2.0 (2–3)0.22
Tumour size, mean (sd)2.7 (1.2)2.6 (1.2)0.59
Laterality (left/right)22/2713/160.99
Proportion with ≥1 prior abdominal procedure, n/N (%)22/49 (45%)17/29 (59%)0.24

Perioperative outcomes are shown in Table 2. Overall, there was no significant difference between the groups with regard to operative time, estimated blood loss, transfusion rates and embolization rates. Mean warm ischaemia time was significantly shorter for Group 2 (SRBS group; P= 0.0013). The proportion of patients with bleeding requiring clinical intervention (open conversion or transfusion ± embolization) was higher for Group 1 (9/49, 18.4% vs 1/29, 3.4%, respectively; P= 0.06). There were no urine leaks in either group.

Table 2.  Perioperative outcomes
DescriptionGroup 1 (Polyglactin suture)Group 2 (V-Loc™)P value
  1. EBL, estimated blood loss; LOS, length of stay.

N4929 
Operative time (min), mean (sd)178 (41)174 (35)0.7
Warm ischaemia time (min), mean (sd)32.8 (7.9)26.4 (8.3)<0.001
EBL (mL), mean (sd)255 (337)188 (205)0.34
Overall complications (by patient), n (%)12/49 (24.4)3/29 (10.3)0.13
 Open conversion2/49 (4.1)0/29 (0)0.27
 Transfusion5/49 (10.2)1/29 (3.5)0.28
 Embolization3/49 (6.1)1/29 (3.5)0.6
 Other complication3/49 (6.1)1/29 (3.4)0.6
LOS, days3.6 (0.98)3.4 (1.3)0.4

DISCUSSION

There have been several innovations in LPN since 2000, which have resulted in its more widespread application as a less invasive alternative to open partial nephrectomy. However, it remains a technically challenging operation and is primarily performed at centres conducting a high volume of minimally invasive urological procedures. The need for efficient intracorporeal suturing during the time constraint of warm ischaemia is a major component of the technical challenge of LPN. In this regard, a noteworthy innovation has been the introduction of robotic-assisted laparoscopic partial nephrectomy (RALPN). In a recent multi-institutional study, Benway et al. [13] found that LPN and RALPN were comparable with regard to early oncological outcomes and perioperative morbidity including clinically significant bleeding, but warm ischaemia times were significantly shorter for RALPN. However, a sub-set analysis revealed that complex tumour configuration (defined as tumours for which collecting system repair was required after excision) was associated with significantly longer warm ischaemia times for both RALPN and LPN.

Innovation in suture design represents a complementary approach to improving suturing efficiency during minimally invasive partial nephrectomy. Shikanov et al. [12] evaluated the use of SRBS for parenchymal repair and renorrhaphy after polar nephrectomy in the porcine model. They showed feasibility and safety, but showed no benefit over conventional absorbable suture with regard to haemostasis or integrity of collecting system closure [12]. In our study, the use of SRBS was associated with significantly decreased warm ischaemia time, but not overall procedure time. In addition, the proportion of patients who experienced clinically significant bleeding (requiring open conversion or transfusion ± embolization) in the SRBS group (1/29, 3.4%) was five-fold lower than for the polyglactin suture group (9/49, 18.4%) with this difference nearly approaching significance (P= 0.06). We believe that this lack of significance is largely the result of the low overall transfusion rate in our series (7.7%) and the small retrospective sample size, which was probably underpowered to detect a significant difference. Indeed, using the published 15% transfusion rate from large series [14], we estimate that to detect a three-fold reduction in transfusion rates (a clinically significant reduction) as observed in the present series, 160 patients per group would be required. Hence, in addition to its clear benefit of decreasing warm ischaemia time, we postulate that with further study the use of SRBS may be shown to decrease haemorrhage rates after LPN.

A few limitations in this study warrant discussion. First the data for warm ischaemia times and rates of postoperative bleeding complications may not be wholly generalizable because they represent the outcomes of a single surgeon after more than 200 previous LPN procedures. Outcomes earlier in the learning curve for LPN would be expected to differ, but the magnitude of this expected difference is difficult to estimate. Second, the mean values for warm ischaemia time and operative time may, in part, be reflective of additional technical improvements in LPN besides the use of SRBS, such as the use of sliding clip renorrhaphy. It is our practice to keep the renal hilum clamped during tumour excision, closure of the inner layer of the resection bed, and renorrhaphy. Our cohort includes patients who underwent LPN between June 2007 and October 2010. Before 2008–09, renorrhaphy was performed using conventional polyglactin suture with intracorporeal knot tying, and subsequently, using the knotless sliding clip technique described by Benway and colleagues [8,9]. Although we would expect an insignificant change in warm ischaemia time with the introduction of knotless renorrhaphy in our experience, a future randomized study would help to minimize this and other potential biases.

CONCLUSION

In early experience with the use of SRBS for parenchymal repair during LPN in humans is safe, and is associated with a significant reduction in warm ischaemia time. Additionally, the self-cinching mechanism of SRBS may be beneficial in reducing rates of clinically significant bleeding after LPN, although this observation warrants further prospective study with larger numbers of patients. Lastly, further studies to identify any benefit of SRBS use during RALPN are needed.

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