Cross-Linked Matrix Tissue Sealant Protects Against Mortality and Hemorrhage in an Acute Renal Injury Model in Heparinized Rats

Potential early predictors for outcomes of experimental hemorrhagic shock induced by uncontrolled internal bleeding in rats

Uncontrolled hemorrhage, resulting from traumatic injuries, continues to be the leading cause of death in civilian and military environments. Hemorrhagic deaths usually occur within the first 6 hours of admission to hospital; therefore, early prehospital identification of patients who are at risk for developing shock may improve survival. The aims of the current study were: 1. To establish and characterize a unique model of uncontrolled internal hemorrhage induced by massive renal injury (MRI), of different degrees (20-35% unilateral nephrectomy) in rats, 2. To identify early biomarkers those best predict the outcome of severe internal hemorrhage. For this purpose, male Sprague Dawley rats were anesthetized and cannulas were inserted into the trachea and carotid artery. After abdominal laparotomy, the lower pole of the kidney was excised. During 120 minutes, hematocrit, pO₂, pCO₂, base excess, potassium, lactate and glucose were measured from blood samples, and mean arterial pressure (MAP) was measured through arterial tracing. After 120 minutes, blood loss was determined. Statistical prediction models of mortality and amount of blood loss were performed. In this model, the lowest blood loss and mortality rate were observed in the group with 20% nephrectomy. Escalation of the extent of nephrectomy to 25% and 30% significantly increased blood loss and mortality rate. Two phases of hemodynamic and biochemical response to MRI were noticed: the primary phase, occurring during the first 15 minutes after injury, and the secondary phase, beginning 30 minutes after the induction of bleeding. A Significant correlation between early blood loss and mean arterial pressure (MAP) decrements and survival were noted. Our data also indicate that prediction of outcome was attainable in the very early stages of blood loss, over the first 15 minutes after the injury, and that blood loss and MAP were the strongest predictors of mortality.

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.

Various Local Hemostatic Agents with Different Modes of Action; an in vivo Comparative Randomized Vascular Surgical Experimental Study

OBJECTIVES

To evaluate the effects of different local hemostatic agents in a new high flow vascular experimental bleeding model.

DESIGN

Bovine thrombin combined with collagen matrix (bTcM), microporous polysaccharide hemospheres (MPH), freeze-dried rFVIIa with and without the combination of MPH were compared to a control group (solely compression) in a randomized fashion (20 animals/group). Primary endpoint was hemostasis, and secondary endpoints were time to hemostasis, blood loss, and blood pressure at hemostasis.

METHODS

The common carotid artery of heparinized rats was ligated proximally and transected. Compression was applied for one minute followed by application of the topical hemostatic agent. Compression was maintained for another two minutes followed by re-evaluation of hemostasis: if bleeding continued additional compression was applied and thereafter bleeding was checked every minute until hemostasis.

RESULTS

All animals in the bTcM group obtained hemostasis compared to 20% in the control group (p<0.0001). The combination of MPH and rFVIIa (70% hemostasis) also showed a significant hemostatic capacity compared to control group (p<0.001). None of the other active treatment groups differed compared to control group. Animals treated with bTcM had a significantly shorter time to hemostasis compared to animals in the other active treatment groups. No significant difference in blood loss and blood pressure at hemostasis was detected.

CONCLUSIONS

The most effective hemostatic agent was bTcM, followed by the combination of rFVIIa and MPH, while neither MPH nor rFVIIa alone displayed any hemostatic capacity compared to compression only.

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.

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.