Local hemostasis during laparoscopic partial nephrectomy using biodegradable hydrogels: initial porcine results

Partial nephrectomy using radiofrequency incremental bipolar generator with multi electrode probe: experimental study in bench pig kidneys

BACKGROUND

The aim of this research project was the realization of an incremental bipolar radiofrequency generator with inline 4-electrode probe for partial renal resection without clamping of the vessels.

METHODS

The experimentation was carried out across two phases: the preliminary realization of a specific generator and an inline multielectrode probe for open surgery (Phase 1); system testing on 27 bench kidneys for a total of 47 partial resection (Phase 2). The parameters evaluated were: power level, generator automatisms, parenchymal coagulation times, needle caliber, thickness of the coagulated tissue "slice", charring, ergonomy, feasibility of the application of "bolster" stitches.

RESULTS

The analysis of the results referred to the homogeneity and thickness of coagulation, energy supply times with reference to the power level and caliber of the needles. The optimal results were obtained by using needles of 1.5 mm caliber at power level 5, and with coagulation times of 54 seconds for the first insertion and 30 seconds for the second.

CONCLUSIONS

The experimentation demonstrated that the apparatus, consisting of a generator named "LaparoNewPro" and fitted with a dedicated probe for open surgery, is able to carry out a coagulation of the line of resection of the renal parenchyma in a homogeneous manner, in short times, without tissue charring, and with the possibility of stitching both on coagulated tissue and the caliceal system. The generator automatism based on the flow of the current supplied by each electrode is reliable, and the cessation of energy supply coincides with optimal coagulation.

Hemostatic strategies for traumatic and surgical bleeding

Wide interest in new hemostatic approaches has stemmed from unmet needs in the hospital and on the battlefield. Many current commercial hemostatic agents fail to fulfill the design requirements of safety, efficacy, cost, and storage. Academic focus has led to the improvement of existing strategies as well as new developments. This review will identify and discuss the three major classes of hemostatic approaches: biologically derived materials, synthetically derived materials, and intravenously administered hemostatic agents. The general class is first discussed, then specific approaches discussed in detail, including the hemostatic mechanisms and the advancement of the method. As hemostatic strategies evolve and synthetic-biologic interactions are more fully understood, current clinical methodologies will be replaced.

Postoperative adhesions after application of topical hemostatic agents: outcomes in a rat partial nephrectomy model

OBJECTIVE

To compare 3 kinds of topical hemostatic agents in terms of adhesive strength, control of hemorrhage, and postoperative intra-abdominal adhesions in an experimental partial nephrectomy (PN) model.

METHODS

A total of 27 Wistar rats were divided into 5 groups. PN was performed in 6 rats (control group) with the conventional technique, in which the lower pole of the kidney was excised and sutured after hilar control. In 5 rats, oxidized cellulose was placed over the excised part of the kidney following conventional technique. In 6 rats, the hemostatic plant extract was used without hilar control. In 5 rats, the hemostatic agent chitosan was used without hilar control. As a sham group, 5 rats underwent a laparotomy and handling of the renal pedicle without the removal of renal pole. On the tenth day after the operation, the degree of adhesions to the operated kidney were evaluated. Histopathological evaluation was also performed by a blinded pathologist.

RESULTS

Mean warm ischemia times for control and oxidized cellulose groups were 4.85 ± 0.75 and 4.28 ± 1.28 minutes, respectively (P = .662). Wound healing was excellent in all groups except in 1 rat in the chitosan group. Chitosan was associated with significantly higher intestinal and peritoneal adhesion scores, although histopathologically comparable scores were revealed.

CONCLUSION

In our rat model, chitosan and the hemostatic plant extract were as effective as conventional suturing in achieving hemostasis even without hilar control. Warm ischemia was eliminated and PN time was significantly decreased. The use of oxidized cellulose was not associated with higher scores of adhesion, suppuration, or hematoma.

A new technique--"lipocorticoplasty"--for the closure of partial nephrectomy defects and its comparison with the standard technique

OBJECTIVE

We describe a new technique that can easily be used as a tension-free practical alternative in closing the renal defects resulting after open partial nephrectomy (PN).

METHODS

A new technique (called "lipocorticoplasty") where "wrapped fatty tissue" was placed in the tumor crater to close the renal defects that occur following PN is reported in 10 consecutive patients who underwent PN between May 2006 and January 2009 (Group I). Patients were compared with equal number of consecutive patients who underwent standard open PN before January 2009 (Group II) in terms of operative time, bleeding, tumor size, drain removal time, postoperative length of stay (PLOS), complications, and functional and oncological follow-up. Postoperative follow-up included physical examination, laboratory tests, and radiological screening at 3-month intervals for the first year, at 6-month intervals for the second year, and annually thereafter.

RESULTS

Mean tumor size (35.2 vs. 33.8 mm), operative time (156 vs. 165 min), bleeding (650 vs. 765 cc), drain removal time (2.8 vs. 2.5 POD), and PLOS (4.4 vs. 4.2 POD) were not statistically different between Group I and Group II, respectively. No intraoperative complications occurred. Postoperatively, transient complications without any permanent sequela were observed in 3 (1 in Group I and 2 in Group II) patients. Mean follow-up time was 16.1 months (7-26) in Group I and 19.1 months (8-36) in Group II. None of the patients had local or systemic recurrence at follow-up.

CONCLUSION

Our new technique provides obvious benefits in local hemostasis, simplifies parenchymal suturing, obviates the need for coaptation of the edges of the tumor bed defect under tension, and minimizes nephron loss due to kinking and tearing of renal parenchyma in the closure of the renal defects following open renal tumor excision.

Hydrogels for tissue engineering and delivery of tissue-inducing substances

This manuscript presents hydrogels (HGs) from a tissue engineering perspective being especially written for those who are approaching this field by offering a concise but inclusive review of hydrogel synthesis, properties, characterization methods, and applications.

A novel synthetic tissue-adhesive hydrogel using a crosslinkable polymeric micelle

We prepared a novel tissue-adhesive hydrogel by using a polymeric micelle consisting of an aldehyde-terminated poly(ethylene glycol)-poly(D,L-lactide) (PEG-PLA) block polymer. A Schiff base is chemically formed between the amino groups in a polyallylamine and the aldehyde groups on the surface of polymeric micelles. The hydrogel was formed in approximately 2 s when the polymeric micelle solution and polyallylamine solution are mixed in vitro. The hydrogel was rapidly formed in vivo, and it adhered to a tissue surface. Our novel tissue-adhesive hydrogel creates no risk of infectious contaminations, because it consists of only synthetic materials. Further, PEG and PLA are known to be biocompatible and noncytotoxic. The results obtained in the present study show that a hydrogel prepared by the formation of a Schiff base between aldehyde and amine groups will potentially address the need for novel tissue-adhesive materials.

Evaluation of polyethylene glycol based hydrogel for tissue sealing after laparoscopic partial nephrectomy in a porcine model

PURPOSE

Polyethylene glycol (PEG) based hydrogel is available as a tissue sealant and hemostatic aid. We determined the long-term safety and efficacy of its use as a tissue sealant for laparoscopic partial nephrectomy in a porcine model.

MATERIALS AND METHODS

A total of 16 swine were cycled to 1 control group and 3 treatment groups, which underwent laparoscopic partial nephrectomy with hemostasis achieved only with application of a biodegradable PEG based hydrogel. The 3 treatment groups were sacrificed at 2, 6 and 12 weeks, respectively. Humoral immune response to the hydrogel used in the porcine abdomen was examined using enzyme-linked immunosorbent assay to detect antibodies in the serum at 0, 2, 6 and 12 weeks. Cell mediated immune response was examined using a lymphocyte proliferation assay to measure the response of leukocytes to various mitogens and antigens, including the polymerized hydrogel, at the same intervals.

RESULTS

Hemostasis was satisfactory after hydrogel application. No adverse effects in the immediate and delayed periods were noted. At 2, 6 and 12 weeks there were no significant differences in hemoglobin or creatinine levels, or in the humoral immune response by enzyme-linked immunosorbent assay. There was no significant difference between test and control pig reactivity to hydrogel as an antigen in the lymphocyte proliferation assay at any time point. Histologically by 6 weeks the animals had almost absorbed the hydrogel with acute inflammation and foreign body reaction resolving by 6 to 12 weeks. No deleterious effect to renal tubules was seen.

CONCLUSIONS

Biodegradable PEG based hydrogel is effective for long-term use as an agent for hemostasis. There was no detectable humoral immune response and no cell mediated immune response to sealant after 2 weeks. This represents promising sealant technology and it should be further investigated for human use.

Evaluation of Hydrogel Tissue Sealant in Porcine Laparoscopic Partial-Nephrectomy Model

BACKGROUND AND PURPOSE

Laparoscopic partial nephrectomy (LPN) is technically challenging with a steep learning curve, primarily because techniques used to control bleeding on the cut surface of the kidney can be ineffective, inconsistent, or challenging. Hemostatic techniques can include intracorporeal suturing, vascular coagulation (argon-beam coagulator, bipolar cautery, laser), and application of various tissue sealants. There is no uniformity of opinion regarding which hemostatic technique is optimal for this application. CoSeal, a hydrogel (Baxter Healthcare Corp, Deerfield, IL), has been effective following vascular surgery but has not been applied to a partial-nephrectomy model. We evaluated the effectiveness of this hydrogel in controlling bleeding and sealing the collecting system by comparing it with intracorporeal suturing and fibrin sealant (Tisseel; Baxter) in a porcine laparoscopic partial-nephrectomy model.

MATERIALS AND METHODS

Bilateral synchronous upper-pole partial nephrectomies were performed in two groups of 18 farm pigs, and the three hemostatic techniques (suturing, Tisseel, CoSeal) were applied. In the first group, partial nephrectomies were performed and the pigs sacrificed 3 days postoperatively (acute group). In the second group, the pigs were euthanized 6 weeks postoperatively (chronic group). In both groups, weight, blood pressure, estimated blood loss, weight of the partial and completion nephrectomy specimen, presence/ absence of urinary leak on retrograde study, histopathologic findings, and complications were recorded.

RESULTS

The mean weight, blood pressure, estimated blood loss, histopathology findings, and weight of the partial and completion nephrectomy specimens were similar in the three groups. CoSeal did not adhere well to the renal parenchyma compared with Tisseel. All three animals in the acute CoSeal group and three of the six pigs in the sutured group had small urinary leaks during retrograde ureteral study, whereas none of the pigs in the fibrin-glue cohort had urinary leaks. There was one complication (urinary leak) in the CoSeal group, necessitating sacrifice of the animal on postoperative day 8 because of sepsis.

CONCLUSIONS

CoSeal is not as effective as fibrin glue in adhering to the cut renal surface and sealing the collecting system during laparoscopic partial nephrectomy.

Use of a novel absorbable hydrogel for augmentation of dural repair: results of a preliminary clinical study

OBJECTIVE

To evaluate the safety and performance of a synthetic dural sealant as an adjunct to standard surgical dural repair techniques to prevent cerebrospinal fluid (CSF) leakage.

METHODS

This study was designed as a prospective, nonrandomized, single-center clinical trial. The dural sealant is a synthetic absorbable hydrogel. Consecutive series of patients scheduled for elective cranial and intradural spinal surgery were included until a total of 50 applications were achieved. It was used primarily as an adjunct to ensure watertight dural closure. The end point was defined as no leak with the Valsalva maneuver after dural sealant application. The patients were followed up for 3 months after surgery to check for CSF leakage, standard laboratory and neurological examinations, and possible adverse advents.

RESULTS

Of the 49 patients, 46 were included and treated with the dural sealant because of spontaneous leak (n = 34; 69%) or leak after the Valsalva maneuver (n = 12; 25%). There was no leak in the other patients (n = 3; 6%). After application of the dural sealant, there was no leak in all 46 patients (100%). Of the 46 patients included, there was one case of overt CSF leak. One patient had a pseudomeningocele. There were no adverse events other than those related to the disease or to the surgical procedure itself.

CONCLUSION

The dural sealant, a synthetic absorbable hydrogel, is a useful adjunct to achieve watertight dural closure. Application resulted in 100% closure of intraoperative CSF leaks. There are no evident adverse effects.

EVALUATION OF MICROPOROUS POLYSACCHARIDE HEMOSPHERES AS A NOVEL HEMOSTATIC AGENT IN OPEN PARTIAL NEPHRECTOMY: FAVORABLE EXPERIMENTAL RESULTS IN THE PORCINE MODEL

PURPOSE

Microporous polysaccharide hemospheres (MPH, Medafor, Minneapolis, Minneapolis) are a novel hemostatic agent made from purified plant starch. MPH activates the clotting cascade and hyperconcentrates platelets and coagulation proteins, while enhancing a hemostatic plug. We evaluated the hemostatic efficacy of MPH compared with standard surgical technique in a porcine open partial nephrectomy model.

MATERIALS AND METHODS

Standardized lower pole partial nephrectomy was consecutively performed in each kidney of 12 female pigs. Each pig was randomized to 2 groups, namely treatment with MPH application or control with the conventional surgical technique (oxidized cellulose with bolster sutures). The right kidney was harvested 1 half-hour after hemostasis was achieved and the left kidney was harvested after 7 days.

RESULTS

Mean animal and resected renal tissue weight were comparable. Ischemic and hemostasis times were significantly decreased in the MPH treated group (2.67 and 4.67 minutes, respectively) vs the control group (8.33 and 7.75 minutes, respectively) (each p = 0.004). Blood loss was equivocal (0.88 gm in the treatment group vs 2.09 gm in the control group, p = 0.07). No hemostatic complications were noted in either group. No evidence of residual foreign material was found in the MPH group at 1 week.

CONCLUSIONS

MPH provided rapid, effective and durable hemostasis in the porcine open partial nephrectomy model. Additional experimental and clinical evaluation is warranted to define the role of MPH assisted partial nephrectomy in humans.

Hand-Assisted Laparoscopic Partial Nephrectomy

The resurgence of nephron-sparing surgery for selected renal masses has fueled interest in minimally invasive approaches. Several authors have shown that laparoscopic partial nephrectomy is feasible if two goals are met: resection of the mass with negative margins and control of bleeding. The latter is a particular challenge, but numerous options are available. The authors describe the operative technique and the available results of hand-assisted laparoscopic partial nephrectomy.

Toward optimal tissue sealants for neurosurgery: use of a novel hydrogel sealant in a canine durotomy repair model

OBJECTIVE

Watertight dural repairs are difficult to achieve, and cerebrospinal fluid leakage causes complications and extends hospital stays. Therefore, a novel synthetic hydrogel film was evaluated as an adjunct to dural closure in a canine model.

METHODS

The self-polymerizing, absorbable, and biocompatible hydrogel was sprayed onto tissue and formed a flexible, adherent sealant. A 2-cm incision of cranial dura and arachnoid was created in 26 adult dogs and loosely repaired. Hydrogel was applied over the 2-mm dural gap in 13 dogs; 13 control dogs received no hydrogel application.

RESULTS

All dogs remained neurologically intact. Valsalva tests conducted at 1, 4, 7, and 56 days were associated with mean leakage pressures (+/- standard error of the mean) of 5 +/- 0, 5 +/- 0, 7 +/- 2, and 13 +/- 8 cm H(2)O in the controls and of 53 +/- 2, 37 +/- 11, 42 +/- 6, and 48 +/- 4 in the treated animals (P = 0.001, 0.053, 0.010, 0.035, respectively, at each time point; one-tailed t test). Histopathological analysis revealed minimal changes.

CONCLUSION

The hydrogel-treated animals exhibited normal progression of dural healing, no dural adhesions, and no underlying effects on the brain. Although dural healing progressed normally, the control animals displayed marked peridural adhesions. The results of this in vivo study suggest that hydrogels, such as that used here, may significantly decrease cerebrospinal fluid leakage, thereby increasing the safety and effectiveness of dural closure in patients and facilitating surgical reexploration.

Bipolar needle electrocautery for laparoscopic partial nephrectomy without renal vascular occlusion in a porcine model

OBJECTIVES

To report a novel method of accomplishing laparoscopic lower pole partial nephrectomy in an acute porcine model using a bipolar needle electrode without the need for renal arterial occlusion.

METHODS

Six animals (12 renal units) underwent laparoscopic polar nephrectomy using the bipolar needle electrode. After complete laparoscopic mobilization of the lower pole of the kidney, the bipolar needle electrode was repeatedly inserted full-thickness into the renal parenchyma and applied transversely, creating regional ischemia to the entire lower pole without renal vascular occlusion. The specimen was then amputated using laparoscopic scissors.

RESULTS

For the 12 laparoscopic partial nephrectomies, the mean operative time was 39 +/- 30 minutes, and the mean blood loss was 90 +/- 112 mL. Of the 12 cases, 10 (83%) were performed successfully with the bipolar needle electrocautery as the only source of hemostasis and without the need for ancillary hemostatic measures. Two of the procedures (17%) required temporary arterial control for hemostasis. For the successful procedures, the mean operative time was 29 +/- 4 minutes, and the mean blood loss was 48 +/- 11 mL. Histologic analysis of the specimens demonstrated coagulative necrosis between 2 and 4 mm from the line of the surgical incision.

CONCLUSIONS

Bipolar needle electrocautery is a promising device that can be used to facilitate laparoscopic partial nephrectomy with minimal blood loss and without the need for renal arterial occlusion and warm ischemia. Additional studies are required to optimize the delivery parameters of this device.

Renal parenchymal hemostatic aids: glues and things

PURPOSE OF REVIEW

Open partial nephrectomy is now recognized as the standard of care for small renal parenchymal tumors. Significant technical problems remain with regard to performing this procedure laparoscopically, namely warm renal ischemia during occlusion of the renal vascular pedicle and renal parenchymal bleeding following tumor excision and release of pedicle control. This article reviews the recent literature in the field of renal parenchymal hemostasis and its role in improving outcomes and increasing applicability for laparoscopic nephron-sparing surgery.

RECENT FINDINGS

Two themes emerge in reviewing the recent literature on renal hemostasis: the use of increasingly advanced tissue sealants and the use of physical methods. Advances in both areas are covered in this article.

SUMMARY

Laparoscopic partial nephrectomy has been developed in an attempt to reduce the morbidity of the open technique. We believe that advances in secure renal parenchymal hemostasis will increase the applicability of the laparoscopic procedure and bring it within the grasp of ordinary urologists.