Conventional Suture Technique Research Articles

Laser ureteral anastomosis using intraluminal albumin stent in a porcine model.

We compared ureteral anastomosis using a laser and intraluminal albumin stent with both conventional suturing and laser soldering techniques. Twelve pigs underwent bilateral ureteral anastomoses (N = 24) using one of the three anastomotic methods: (1) laser welding with intraluminal albumin stent (N = 11); (2) with albumin solder (N = 8); and (3) conventional suturing (N = 5). Operative parameters, leakage rate, intrapelvic perfusion pressure, urography, and histology of the anastomoses were examined. Operative time for ureteral anastomosis in the stent and solder groups were significantly shorter than the suture group (means 370 seconds and 360 vs. 710 seconds, both P = 0.02). Leakage rate of the anastomoses was lower in the stent group (9%, 1/11) as compared to the solder group (25%, 2/8). The Whitaker test showed that the intrapelvic perfusion pressure elevated gradually after anastomosis and significantly increased at 4 weeks postoperatively in all three methods. Various degrees of hydronephrosis were also noticed in three groups after 4 weeks of surgery. Use of the intraluminal albumin stent increased the reliability of laser welding for ureteral anastomosis. The clinical significance of using this technique should be investigated further.

Secure flap fixation to bony tissue using an anchoring system in skull-base surgery.

The reconstruction of extensive skull-base defects using flap transfer decreases crucial postoperative complications. However, flap fixation to bony tissue is often difficult, especially if there is no soft tissue to pass sutures through, and unsteady flap fixation causes dead space formation or displacement of the transferred flap due to gravity. The authors used an anchoring system for secure flap fixation in seven cases with difficult flap fixation, using the conventional suturing technique. Anchors were inserted at strategic points in the bony tissue, and secure flap fixation was achieved in all cases. Postoperative CT scans showed no dead space formation, and major postoperative complications were not observed. The anchoring system can be buried in bony tissue with a thickness of more than 4 mm, and it enables reliable flap fixation and dead space obliteration. Although the cost is relatively high, the procedure is simple and lowers the risk of crucial postoperative complications in skull-base surgery.

Clips metálicos VCS: una técnica de sutura más rápida y fácil de utilizar que la sutura convencional en reconstrucciones de vasos en crecimiento

Summary Introduction The latest generation of titanium clip appliers, called VCS (vascular closure staples) instruments, not only avoid damage being done to the tunica intima and hyperplasia while at the same time favouring the distensibility and growth of the vessel, but also provide the surgeon with a fast, easy-to-use method, which contrasts with the conventional discontinuous suture technique using polypropylene. This can be the method chosen for use in the reconstruction of vascular elements that are growing (paediatric aorta surgery and transplants), and where lowering the clamping time is important. Aims The purpose of this study was to check whether suturing with metallic VCS clips could be a faster method for the surgeon than conventional discontinuous suturing with polypropylene in end-to-end anastomosis of arteries and veins. Materials and methods At the age of 55 days, 30 lambs were submitted to end-to-end anastomosis in the carotid artery and the jugular vein. Results. It was confirmed that VCS clip appliers are easier for the surgeon to use and significantly lower the time needed to perform end-to-end anastomosis of arteries (clips, 4.02 ± 0.72 min; suture, 21.89 ± 1.93 min) and of veins (clips, 9.82 ± 3.97 min; suture, 29.31 ± 1.90 min). Conclusions VCS clips significantly reduce the time employed to perform end-to-end anastomosis of arteries and veins as compared to the conventional discontinuous technique using polypropylene.

Quantitative evaluation of abdominal wall perfusion after different types of laparotomy closure using laser-fluorescence videography.

Laparotomy closure relies on the incisional edges as anchor for the suture material. The results of these techniques are not satisfying, with failure rates of up to 20%. To investigate the effect of different conventional closure techniques and a novel "bridging technique" on abdominal wall perfusion an animal study was performed in rabbits. Abdominal wall perfusion was measured using the method of dynamic laser-fluorescence videography in the first 72 h of incisional wound healing in 25 animals. Suture tension was controlled with a water-filled polyurethane balloon connected to a pressure detector. The effect of laparotomy closure on abdominal wall tissue perfusion depends significantly on the applied technique and suture tension. Avoiding direct sutures in the incisional edges during laparotomy closure leads to a better tissue perfusion of the incisional region than conventional suture techniques. Suture tension can be controlled and adjusted using a water-filled polyurethane balloon as a pressure sensor.

Unconventional vessel wall apposition in off-pump porcine coronary artery bypass grafting: Low versus high graft flow

Objective: Facilitated coronary anastomosis techniques may involve unconventional vessel wall apposition in contrast to standard intima-intima apposition. We assessed the patency, anastomotic thrombus formation, and intimal hyperplasia of unconventional intima-adventitia apposition versus conventional suturing techniques in beating heart coronary bypass grafting under low versus high graft flow conditions. Methods: The intima-adventitia (n = 28) and conventional anastomoses (n = 28) were evaluated intraoperatively (n = 56), at 4 hours (n = 20), and at 5 weeks (n = 36) in a new off-pump low-flow (n = 28) and high-flow (n = 28) porcine bypass model (≤15 mL/min and about 60 mL/min, respectively). The anastomoses were assigned to the animals by means of randomized stratification and examined by means of flow measurements, angiography, and histology. Results: Mean graft flows in intima-adventitia and in conventional anastomoses were similar (P = .709). All but 1 of 56 anastomoses (low flow conventional) were fully patent at the time of death. At 4 hours, only small platelet depositions were found at the exposed media and adventitia in the unconventional anastomoses. At 5 weeks, little streamlining intimal hyperplasia was found, which was comparable between the anastomoses (P = .600). Conclusions: In low-flow conditions (≤15 mL/min) unconventional intima-adventitia apposition was not detrimental to the internal thoracic–coronary artery anastomosis in the pig. This finding may expand design strategies of facilitated coronary artery bypass anastomosis techniques.

Fixation strength of meniscal repair devices

The aim of this study was to measure and compare the ultimate failure strengths and cyclic fatigue strengths of currently available meniscal suturing devices. No statistically significant difference in failure load was found between a vertical loop suture (mean 46.3 N), a horizontal mattress suture (52.5 N), the T-fix Device® (47.5 N), and the 16-mm (39.2 N) and 13-mm (32.8 N) Bionix Arrow®. Statistically inferior results were seen with the 10-mm Bionix Arrow® (18.8 N), the S.D. Sorb Stapler® (4.3 N), and the 12-mm Arthrex Meniscal Dart® (10.5 N) ( P<0.01). The Mitek Meniscal Repair System® (28.1 N) performed intermediate, with significantly better results than the S.D. Sorb Stapler® and the 12-mm Arthrex Dart®, but significantly worse than the vertical and horizontal sutures, the T-fix® and Bionix 16-mm Device® ( P<0.01). Cyclic fatigue strength was significantly less for the 10-mm Bionix Arrow®, the S.D. Sorb Stapler®, and the 12-mm Arthrex Meniscal Dart® ( P<0.01) compared to all other devices. We conclude that the 13- and 16-mm Bionix Arrow® and the T-fix Device® have comparable ultimate failure strengths and cyclic fatigue strengths to conventional meniscal suturing techniques. The 10-mm Bionix Arrow®, S.D. Sorb Stapler®, and the 12-mm Arthrex Meniscal Dart®, however, have far inferior failure and cyclic fatigue strengths and their clinical application should be questioned.

Long-term effects of extraluminal dilatation with a rigid circle on arteriovenous anastomotic line in venous grafts transposed into arterial defects.

Postanastomotic narrowing resulting from subintimal hyperplasia is a well-known phenomenon. In the current study the authors compared a metallic circle and conventional suture technique in anastomoses performed in two ends of external jugular vein grafts interposed in carotid arteries of rabbits. They recorded the patency rates, fluid flow rates, and histological effects of the circle on the anastomotic line and compared them with conventional suture anastomoses. In 16 rabbits (experimental group) a standard suture was used in both ends of the jugular vein graft transposed to the carotid arteries on one side. On the other side, circle anastomoses were performed on both ends of the vein graft. In an additional 8 rabbits (control group), the anterior jugular veins and carotid arteries were dissected on both sides and left. During postoperative week 12, in 8 rabbits of the experimental group, the flow rates of carotid arteries were measured in vitro, and intraluminal silicone casts were prepared. In the remaining 8 experimental rabbits, carotid angiographies were performed and anastomotic segments were harvested for histological examination. Flow rates were also measured in the control group, and artery and vein segments were harvested. The patency rates of the vein grafts with metallic circle anastomoses were 100%, whereas conventional suture patency was 75% at week 12. Flow rates were significantly higher in the metallic circle-anastomosed vein grafts (74 ml per minute vs. 123 ml per minute, mean values; p < 0.05). Histological examination revealed reduced intimal thickness in the metallic circle anastomoses compared with conventional suture anastomoses. Dilatation of the arteriovenous end-to-end anastomotic line by a rigid circle prevents anastomotic narrowing in the long term.

Ultrasound biomicroscopy of conventional and sutureless pars plana sclerotomies: a comparative and longitudinal study

PURPOSE: To report the rate of ultrasonically visible vitreous incarceration and longitudinal changes of incarcerated vitreous in pars plana sclerotomies after conventional suturing or sutureless technique using ultrasound biomicroscopy. METHODS: Twenty-five consecutive eyes (25 patients) undergoing primary three-port pars plana vitrectomy participated. The first 16 pars plana vitrectomies were performed with standard conventional sutured sclerotomies, and the following nine pars plana vitrectomies were performed with modified sutureless sclerotomies. Patient demographics, diagnoses, procedures, and complications were recorded. Each patient had ultrasound biomicroscopy performed 1 week before surgery, and also after surgery at 1 week, 2 weeks, 3 weeks, 4 weeks, 2 months, 3 months, and 6 months. Visible vitreous incarceration was graded as 0 to 3. RESULTS: Vitreous incarceration was seen in 41 of 48 sclerotomies (85.4%) in the conventionally sutured group, and in 23 of 27 sclerotomies (85.2%) in the sutureless group, with no significant difference in severity among sclerotomies within each group and between the two groups. There was a significant difference in the rate of vitreous incarceration between diabetic patients with proliferative retinopathy and others ( P = .002). No progressive change of visible vitreous incarceration was noted in any eye during the 6-month postoperative period. No sclerotomy-related complications occurred during the study period. CONCLUSIONS: Ultrasound biomicroscopy showed no difference in the amount of visible vitreous incarceration in conventionally sutured or sutureless sclerotomies. There was no visible longitudinal change in the incarcerated vitreous during the 6 months of follow-up in uncomplicated cases.

Meniscus reconstruction. Established and innovative methods

After the first description of meniscus repairs in the literature it took nearly a century until they were routinely performed in orthopaedic surgery. The scientific basis for meniscus reconstruction needed to be elaborated, including the study of the anatomy, and for instance the vascularisation and the function of the meniscus. After the first experiences with open repair, several arthroscopic techniques have been developed. It has been shown that several factors could influence the healing rate of meniscus lesions. One of the major factors is knee stability. Meniscus repairs performed in conjunction with reconstruction of the anterior cruciate ligament (ACL) have shown higher healing rates (generally > 75%) than isolated repairs, either in stable (50-75% healing rate) or in unstable knees (< 50% in some studies). The localization of the tear is probably the most important factor influencing the healing rate of meniscus repairs. Peripheral tears which are located in the vascular zone of the meniscus heal better than centrally located tears in the avascular area. Many efforts have been provided to enhance the vascularity in this part of the meniscus. None of the proposed techniques have been proven to be definitively effective, or they are too demanding for routine use. Conventional meniscus suture techniques are time-consuming, technically demanding and necessitate incisions at risk for neurovascular structures. In order to simplify meniscus repair several new implants have been developed. They have different forms and are made of different materials among which some are biodegradable. The first clinical results with these techniques are encouraging. However, some new complications have been described. Their incidence and the fate of intraarticular biodegradable devices still has to be defined, especially in the long-term. The present study describes the actual knowledge of meniscus repair and presents the new techniques. It also shows that several questions concerning meniscus repair still need to be answered, and points out the need for further controlled studies.

Eversion with four sutures: an easy, fast, and reliable technique for microvascular anastomosis.

In this study, a microvascular anastomosing technique called "eversion with four sutures" is introduced. For microvascular anastomosis, this technique requires fishmouth incisions at both vessel ends and the completion of four sutures. In 120 Wistar-Albino rats, 120 eversion and 120 conventional anastomoses were done in 240 femoral arteries. Each rat received both treatments. Operating time, bleeding time, number of sutures used, patency rates, and pseudoaneurysm formation were analyzed statistically; healing was evaluated with both light and electron microscopy. When compared with the conventional technique using nine sutures, the eversion with four sutures technique was found to be a faster and easier method of anastomosis and as reliable as the conventional technique. Without compromising patency rates, bleeding time, or rates of pseudoaneurysm formation, anastomosis time and amount of suture material exposed to the lumen were significantly reduced when using this technique. In conclusion, the authors think that eversion with four sutures is a reliable alternative to the conventional suturing technique, especially for emergency cases that require multiple microvascular anastomoses.

Venous anastomoses with a microvascular anastomotic device in head and neck reconstruction.

The Microvascular Anastomotic System (3M coupler) uses a friction-fit union of implant rings composed of high-density polyethylene and stainless-steel pins. Several reports have described equal or greater patency rates, as well as more rapid performance, using the device, compared to conventional suturing techniques. Eighty-nine patients, who underwent head and neck surgery with free-tissue transfers, using the Microvascular Anastomotic System, were evaluated. A hundred and twenty-one venous anastomoses were done using the device. All but one was done in an end-to-end manner Arteries were anastomosed with a conventional suture technique. The flap survival rate was 100 percent. The authors conclude that the device is reliable and time-sparing for end-to-end venous anastomoses in head and neck reconstruction.

Sutureless microvascular anastomoses by a biodegradable laser-activated solid protein solder.

A new sutureless technique to successfully anastomose the abdominal aorta of rats (1.3 mm in diameter) by using a fully biodegradable, laser-activated protein solder is presented. A total of 90 rats were divided into two groups randomly. In group one, the anastomoses were performed by using conventional microsuturing technique, whereas in group two, the anastomoses were performed by using a new laser welding technique. In addition, each of the two groups were divided into five subgroups and evaluated at different follow-up periods (10 minutes, 1 hour, 1 day, 1 week, and 6 weeks). At these intervals, the anastomoses were evaluated for patency and tensile strength. Three anastomoses in each subgroup were processed for light and electron microscopy. All anastomoses were found to be patent. The mean clamp time of the anastomoses performed with conventional suturing was 20.6 minutes compared with 7.2 minutes for the laser-activated welded anastomoses (p < 0.001). The strain measurements showed a stronger mechanical bond of the sutured anastomoses in the initial phase. However, at 6 weeks the tensile strength of the laser-welded anastomoses was higher compared with the conventional suture technique. Histologic evaluations revealed a near complete resorption of the solder after 6 weeks. The junction site of the vessel ends cannot be determined on the luminal side of the artery. In conclusion, a resorbable protein used as a solder, activated by a diode laser, can provide a reliable, safe, and rapid arterial anastomosis, which could be performed by any microsurgeon faster than conventional suturing after a short learning curve.

Clinical experience in end-to-side venous anastomoses with a microvascular anastomotic coupling device in head and neck reconstruction.

Microvascular anastomosis remains one of the most technically sensitive aspects of free-tissue transfer reconstructions. Despite the availability of various mechanical anastomotic coupling systems for human clinical use during the last 8 years, reported clinical series remain rare. To describe a clinical experience in applying a mechanical microvascular anastomotic coupling device (MACD) to end-to-side anastomotic configurations in head and neck free-flap reconstruction. The MACD is a readily available high-density polyethylene ring-stainless steel pin system that has been found to be highly effective in clinical studies of end-to-end arterial and venous anastomosis and in laboratory studies of end-to-side anastomosis of rabbit arteries. Thirty-seven end-to-side venous anastomoses were attempted, of which 33 (89%) were completed. Of these, 9 patients had critical anastomoses (only 1 venous anastomosis per patient). In patients undergoing parallel venous anastomoses, 6 had both anastomoses performed using the MACD; in the remaining 12 patients, 1 of the anastomoses was performed using the MACD. A variety of donor flaps and clinical contexts were encountered. Flap survival in the MACD series was 100%. Four anastomoses were converted to conventional suture technique intraoperatively. The MACD is well suited to end-to-side venous anastomosis when carefully and selectively used by experienced microvascular surgeons. The most common clinical situation requiring this configuration and technique was the lack of ipsilateral recipient veins for end-to-end anastomosis or a ligated internal jugular vein stump that required this approach for device application. Previous radiation therapy does not appear to be a contraindication to its use.

Laparoscopic hernia repair -- the facts, but no fashion.

For about 10 years now, laparoscopic hernia surgery has been introduced as an additional mode of therapy in the treatment of inguinal hernias. This method is being reproached with higher costs of surgery and rate of complications, as well as missing long-term results. Within a literature research, data from 25 randomised trials and 16 prospective observational studies on endoscopic and conventional hernia surgery were evaluated. Statistics were calculated using the chi2 test. Compared with the conventional suture technique and tension-free surgery, the endoscopic repair proved to be advantageous with regard to postoperative pain and period of disablement. There was no significant difference between the methods when evaluating the rate of complications. In two randomised trials, there was a significant difference in favour of endoscopic repair with regard to the recurrence rates, whereas in the other studies a significant difference could not be shown. In the prospective series, recurrence rates were 0.71% for totally preperitoneal repair (TEP) and 1.06% for transabdominal preperitoneal repair (TAPP) repair. Endoscopic hernia surgery (TAPP and TEP) represents an efficient method of treatment in the therapy of inguinal hernias. Recurrent and bilateral hernias can be seen as an absolute indication for endoscopic repair.

An absorbable pinned-ring device for microvascular anastomosis of vein grafts: Experimental studies

In the rabbit, posterior facial vein segments were grafted to the femoral arteries using either conventional suture technique or a mechanical absorbable pinned-ring device. The purpose of this study was to compare patency rates and anastomotic times for the two different methods. The anastomoses were evaluated macroscopically and using light and scanning electron microscopy. The grafts anastomosed with the absorbable rings exhibited 100% patency, while only 83% of the sutured grafts were patent. The mean anastomotic time using the mechanical pinned-ring device was 18.1 min (range 9.8-30 min). The conventionally sutured anastomoses were completed in a mean time of 60 min (range 50-75 min). The experiment has confirmed that the absorbable pinned-ring device provides a safe and fast way to perform microvascular anastomosis.

A Modified Method of Continuous Venous Anastomosis in Microsurgery

The continuous suture technique for end-to-end vascular anastomosis is cautioned against because of the risk of vessel constriction. A modified method of continuous suture for end-to-end venous microanastomosis is presented in which vessel constriction does not occur. This technique was compared with the conventional interrupted suture technique in the rat femoral vein, with each rat serving as its own control. Forty-eight Long-Evans rats were used. The mean time taken to complete the anastomosis was 9.8 minutes (range, 8-14 minutes) for the modified continuous technique and 17.7 minutes (range, 14-24 minutes) for the conventional interrupted technique (p < 0.05, independent t-test). In addition, the veins were examined under the microscope for patency and the milk test was performed on each anastomosis 30 minutes postanastomosis, and 1 week and 1 month postoperatively. Two groups of rats were sacrificed, one at 1 week and one at 1 month, and the two different anastomoses were compared using vessel morphometry in 40 rats and corrosion casts in 8 rats. All veins were patent postoperatively, as well as at 1 week and 1 month postoperatively. Vessel morphometry confirmed a similar luminal surface area in all veins examined at 1 week and 1 month. A two-way analysis of variance of vessel morphometry indicated no significant interaction between the methods used and the postoperative time (p = 0.60). The modified continuous technique is twice as quick as the conventional interrupted technique for end-to-end microvenous anastomosis and does not lead to vessel constriction.

FIBRIN-GLUE ASSISTED VASOEPIDIDYMOSTOMY: A COMPARISON TO STANDARD END-TO-SIDE MICROSURGICAL VASOEPIDIDYMOSTOMY IN THE RAT MODEL

The use of fibrin glue for vasovasostomy has produced high patency rates in animal models. Vasoepididymostomy is a microsurgical technique that might be made easier if fibrin glue could substitute for microsutures. We evaluated the efficacy of a new vasoepididymostomy technique using fibrin glue. Bilateral vasoepididymostomies were performed in 24 male Sprague-Dawley rats using a conventional microsurgical technique on one side and a fibrin-glue assisted technique on the other. The rats were sacrificed 30 days after surgery and anastomotic patency was assessed by examining the vasal fluid for sperm, injecting methylene blue dye into the vas deferens and observing backflow into the epididymis by gross inspection and histological studies. Additionally, the incidence of granuloma formation was compared between the two techniques. Fibrin-glue anastomoses showed a patency rate of 79% (n = 19), compared with 63% (n = 15) for the conventional suture anastomoses (p = 0.29). Among the patent anastomoses, the incidence of sperm granuloma formation between the sutured (12, 50%) and the fibrin glue anastomoses (16, 67%) did not differ significantly (p = 0.36). Morphological tissue changes were similar for the two techniques. The time required for anastomosis using fibrin glue was significantly shorter than the conventional suture technique (p < 0.001). Conventional suturing techniques for vasoepididymostomy require advanced microsurgical skills. The use of fibrin glue simplifies this procedure and provides patency rates comparable to microsutured, end-to-side anastomoses.

IMPLANTATION OF AN INTRALUMINAL RINGED PROSTHESIS IN HIGH-RISK PATIENTS WITH ACUTE AORTIC DISSECTION TYPE I

Surgical therapy for acute dissection of the ascending aorta has had a high mortality. The contributing factors have been hemorrhage from the suture lines and pulmonary dysfunction following a prolongation of extra corporeal circulation (ECC) time. A method of treatment with an intraluminal prosthesis that requires no end-to-end anastomosis has been developed. We have used this method in two patients, who had acute aortic dissections type I and high risks. The first case involved a patient of advanced age and had poor pulmonary function. The second case involved a patient with poor liver function and decreased blood platelet count. The sutureless fixations shortened ECC times which were 98 and 107 minutes in the first and second cases, respectively and reduced blood loss. There were neither hospital deaths nor early graft-related complications. Our experience with these cases suggests that grafting of the aorta is less hazardous with the sutureless than with the conventional sutured anastomosis technique in the high risk patients.

Laser welding with albumin-based solder: experimental full-tubed skin graft urethroplasty.

Fistula and stricture formation at the site of sutured anastomoses are frequent complications of major urethroplasty. We performed urethroplasty using laser-welded skin tube grafts in the hope that in addition to being free of suture holes, grafts would be as strong as or stronger than sutured controls. Scrotal skin was harvested from each of 11 rabbits and fashioned into tubes 3-4 cm in length using either conventional suture techniques or laser welding. Welding was performed using an 808-nm diode laser and a dye-enhanced solder composed of albumin and sodium hyaluronate. Laser power density was 15.9 watts/cm2. For each graft, leak pressure, and urethroplasty time (tube creation and anastomosis to native urethra) were measured. Urethroplasty time was significantly shorter and initial leak pressures were seven times greater in the laser-welded group. The near-uniform occurrence of strictures in both groups suggests that the rabbit is not an ideal model for free tube graft urethroplasty. However, our data indicate that laser welding with albumin-based solder, when used in the appropriate setting, may offer the potential for the rapid creation of watertight grafts in reconstructive urology.

Clinical experience with a microvascular anastomotic device in head and neck reconstruction

Despite numerous refinements in microsurgical technique and instrumentation, the microvascular anastomosis remains one of the most technically sensitive aspects of free-tissue transfer reconstructions. Concurrent with the development of microsurgical techniques, various anastomotic coupling systems have been introduced in an effort to facilitate the performance and reliability of microvascular anastomoses. The microvascular anastomotic coupling device (MACD) studied here is a high-density, polyethylene ring-stainless steel pin system that has been found to be highly effective in laboratory animal studies. Despite its availability for human clinical use over the last 5 years, reported clinical series remain rare. Our clinical experience with this MACD in 29 head and neck free-tissue transfers is reported herein. Thirty-five of 37 (95%) attempted anastomoses were completed with 100% flap survival with a variety of donor flaps, recipient vessels, and clinical contexts. Two anastomoses were converted to conventional suture technique intraoperatively, and one late postoperative venous thrombosis occurred after fistulization and vessel exposure. We conclude that the MACD studied here is best suited for the end-to-end anastomosis of soft, pliable, minimally discrepant vessels. Previous radiation therapy does not appear to be a contraindication to its use. Interpositional vein grafts may also be well suited to anastomosis with the device. When carefully and selectively employed by experienced microvascular surgeons, this MACD can be a safe, fast, and reliable adjunct in head and neck free-tissue transfer reconstructions, greatly facilitating the efficiency and ease of application of these techniques.