Update on hemostasis: neurosurgery

Tranexamic Acid in Reducing Intraoperative Bleeding in Dogs Undergoing Thoracolumbar and Lumbar Hemilaminectomy and Intervertebral Disc Fenestration

Hemilaminectomy associated with intervertebral disc fenestration (HF) is the most used spinal decompression surgical technique for the treatment of intervertebral disc extrusion (IVDE). The surgical procedure can be hampered by excessive bleeding from the venous sinuses; however, tranexamic acid intravenously (IV) is a possible adjunct to hemostasis in these patients. This study aimed to verify the effectiveness of tranexamic acid in reducing intraoperative bleeding in dogs with thoracolumbar and lumbar IVDE submitted to HF. Sixteen dogs with IVDE undergoing HF were included. These were distributed into a TXA group (tranexamic acid 20 mg/kg IV bolus, followed by 2 mg/kg/h IV continuous infusion) (n = 8) and a control group, with saline solution (n = 8). Blood loss was measured using the gravimetric method. The difficulty of operative visualization due to bleeding was classified by the surgeon. Median blood loss (%) in patients in the TXA group was lower than those in the control group (2.75 ± 1.23 and 4.99 ± 4.44, respectively) (P = .028). Intraoperative visualization difficulty due to bleeding occurred in 10 patients in the control group, and in no patients in the TXA group. A severe arterial thromboembolic complication was recorded, potentially due to tranexamic acid. The use of intraoperative tranexamic acid was effective in reducing bleeding and facilitating operative visualization in dogs with IVDE undergoing hemilaminectomy and intervertebral disc fenestration.

The potential of chitosan-based haemostats for use in neurosurgical setting - Literature review

Haemorrhage is a major nuance in neurosurgery since blood can distort the surgeon's field of view and increase the risk of post-operative complications. Currently a variety of commercially available haemostats have been approved for use in neurosurgery, but they have caveats to their use in the brain, including, localised tissue compression, neural toxicity, induce immune reaction or form thrombus within the vessel. Thus, there is a need for haemostats that are efficacious and safe for application on brain and spinal tissue. Chitosan is a naturally occurring bio-polymer that is found on the exoskeleton of arthropods and the cell wall of fungi. Chitosan has been shown to accelerate haemostasis through a myriad of physiological pathways. These findings have led to the development of multiple chitosan-based haemostats, for use in peripheral human tissue. Although, clinical data regarding the use of chitosan-based haemostats in the brain is lacking, a range on in vivo studies have proven chitosan to be efficacious and safe in managing neurosurgical bleeds. Similarly, literature comparing chitosan-based haemostats with commercial haemostats used commonly in neurosurgery, have all demonstrated chitosan to be the superior agent. Additionally, clinical trials of chitosan-based haemostat used in peripheral tissue have all demonstrated chitosan to be safe for human use. The marriage of these findings indicates that the safety and superior efficacy of chitosan-based haemostat, makes it a potentially suitable haemostat for use in neurosurgical setting. However, further research pertaining to the clinical use of chitosan-based haemostat within the central nervous system needs to be conducted.

The effect of chemical and structural modifiers on the haemostatic process and cytotoxicity of the beta-chitin patch

Beta-chitin patch has previously been proven to be an effective haemostat, but whether modifying the patch affects its efficacy and safety, remains unanswered. In this study, the patch was modified using polyethylene oxide, Pluronic-F127, calcium, increased thickness or polyphosphate, and their effect on the process of haemostasis and cytotoxicity was tested and compared with standard-of-care, Surgicel and FloSeal. Whole blood collected from volunteers was applied to the patches to test their whole blood clotting and thrombin generation capacities, whilst platelet isolates were used to test their platelet aggregation ability. The fluid absorption capacity of the patches was tested using simulated body fluid. Cytotoxicity of the patches was tested using AlamarBlue assays and PC12 cells and the results were compared with the standard-of-care. In this study, beta-chitin patch modifications failed to improve its whole blood clotting, platelet aggregation and thrombin generation capacity. Compared to non-modified patch, modifications with polyethylene oxide or calcium reduced platelet aggregation and thrombin generation capacity, while increasing the thickness or adding polyphosphate decreased platelet aggregation capacity. The cytotoxicity assays demonstrated that the beta-chitin patches were non-toxic to cells. In vivo research is required to evaluate the safety and efficacy of the beta-chitin patches in a clinical setting.

[Local application of recombinant activated factor VII for massive surgical bleeding]

The authors report resection of anaplastic convexital meningioma in a middle-aged woman complicated by expected massive blood loss. The most intense bleeding occurred at the final stage of resection and it was impossible to stop it with traditional approaches. The surgeon pressed a standard tachocomb plate moistened with a diluted solution of recombinant activated factor VII (coagil, Russia) to the most bleeding area for 5 minutes. Subsequently, surgeon replaced finger pressure with a permanent napkin. Hemostatic effect of recombinant activated factor VII following its systemic administration is well known and convincingly proven in many surgical areas including neurosurgery. However, we do not know any descriptions of its local application in neurosurgical patients.

Magnesium and Risk of Bleeding Complications From Ventriculostomy Insertion

BACKGROUND AND PURPOSE

Hemorrhages are a serious complication of brain surgery, and magnesium has shown hemostatic properties in hemorrhagic stroke and non-neurological surgeries. External ventricular drain (EVD) insertion is an advantageous model of emergency neurosurgical hemorrhage risk because it is common, standardized, and the operator is blinded to the outcome during the procedure. We tested the hypothesis that low magnesium is associated with risk of hemorrhagic complications from EVD insertion.

METHODS

Patients with spontaneous intracerebral hemorrhage and aneurysmal subarachnoid hemorrhage were enrolled in a prospective, observational study. Demographic and clinical variables were prospectively recorded, including serum magnesium measurements. Catheter tract hemorrhage (CTH) was measured on postoperative head computed tomography within 48 hours of EVD insertion.

RESULTS

We observed 50 CTH among 327 EVD procedures (15.3%) distributed similarly among intracerebral hemorrhage (21/116 [18.1%]) and subarachnoid hemorrhage (29/211 [13.7%]). Magnesium was lower in patients with CTH compared with those without (median 1.8 versus 2.0 mg/dL, P<0.0001). Higher magnesium was associated with lower odds of CTH (odds ratio 0.67 per 0.1 mg/dL magnesium [95% CI, 0.56-0.78], P<0.0001) after adjustment for other risk factors, with similar effect in the intracerebral hemorrhage and subarachnoid hemorrhage subgroups. Preprocedural increase in magnesium (odds ratio 0.68 [0.52-0.85]) and dose of preprocedural magnesium sulfate (odds ratio 0.67 [0.40-0.97]) were associated with reduced CTH risk after adjustment for initial magnesium and other risk factors.

CONCLUSIONS

Lower magnesium at the time of EVD insertion was an independent predictor of hemorrhagic complications. Baseline risk was attenuated by preprocedural increases in magnesium, suggesting a therapeutic opportunity.

Floseal only versus in combination in spine surgery: a comparative, retrospective hospital database evaluation of clinical and healthcare resource outcomes

OBJECTIVE

Flowable agents such as Floseal® (F) are often reserved as adjuncts to non-flowable agents (i.e. gelatin (G) sponges and thrombin (T)) when bleeding is not sufficiently controlled. Based on their perceived positive impact, it is postulated that flowable agents alone may result in better clinical and resource utilization outcomes. Clinical and health-care utilization outcomes were compared in this retrospective analysis of spine surgery cases with charges for Floseal only (FO) and F + G/T.

METHODS

The United States Premier Hospital Database was searched for adult spine surgeries performed between October 2010 and September 2015 with FO or F and G/T charges. To obtain an unbiased treatment estimate, 1:1 propensity-score matching was used to identify FO and F + G/T cohorts. The cohorts were compared for rates of intraoperative, perioperative, postoperative and transfusion; blood loss-related, serious and other complications; hospital length-of-stay (LOS), surgical time, and volume of hemostat charged.

RESULTS

Among 40,335 spine surgeries, 15,105 FO and F + G/T matched pairs were compared. Significantly (p < 0.0001) lower percentages of FO than F + G/T cases received intraoperative (1.4% vs. 2.5%), perioperative (1.6% vs. 2.8%), postoperative (1.6% vs 3.0%), and any transfusion (2.3% vs. 4.3%). FO cases had significantly less blood loss complications than F + G/T cases (0.5% vs. 0.8%, p = 0.0022) and significantly (p < 0.0001) shorter hospital LOS (-0.45 days), surgical time (-39.0 min), and used less hemostat (-12.5 mL).

CONCLUSIONS

Results from this observational hospital database analyses indicate that FO use in spine surgery is associated with lower blood transfusion use and blood loss complications compared to its use with adjunct non-flowable hemostatic agents. The shorter hospital stay, reduced surgical time, and less hemostat volume health-care utilization outcomes that favored FO versus combination use may translate to health system cost savings. Further validation of these findings using controlled clinical trials and cost-consequence studies is warranted.

CLINICAL RELEVANCE

The use of flowable hemostatic agents alone may result in better clinical and possibly economic outcomes in spine surgery.

Chitosan Pad, Cellulose Membrane, or Gelatin Sponge for Peridural Bleeding: An Efficacy Study on a Lumbar Laminectomized Rat Model

Study Design

Experimental study in an animal model.

Purpose

This study aims to evaluate the hemostatic properties of four common hemostatic materials including the chitosan clot pad, absorbable gelatin sponge, cellulose membrane, and gauze on peridural bleeding using a rat model.

Overview of Literature

Intraoperative bleeding during spinal surgery can lead to morbidities. Hemostatic materials have been developed, but the efficacy of these materials on peridural bleeding remains unclear.

Methods

Forty 8-week-old Sprague-Dawley rats were used in this study. Under adequate anesthesia, each rat was posteriorly dissected to their L5 and L6 spinous processes. Bleeding from muscles and soft tissue dissections was stopped before lumbar bone cutting. Immediately after the L5-L6 laminae were cut and removed, the rats were randomly allocated to receive one of the abovementioned hemostatic materials. All hemostatic materials were placed over the raw surface of cut bone and dura and changed every 60 seconds. The procedure was stopped when there was no further bleeding. Time to staunching and amount of bleeding were recorded for statistical analysis.

Results

The respective mean±standard deviation hemorrhage volume and time for the cellulose membrane, gelatin sponge, chitosan pad, and gauze were 1.19±0.44, 1.03±0.72, 0.96±0.57, and 1.98±0.62 mL, respectively, and 2.9±0.6, 2.1±0.6, 1.7±0.5, and 2.9±1.0 minutes, respectively. The overall bleeding volumes for the cellulose membrane, gelatin sponge, and chitosan pad were significantly lower than the overall bleeding volume for gauze.

Conclusions

Chitosan clot pads, gelatin sponges, and cellulose membranes have better hemostatic properties than gauze. The chitosan pad had the lowest average bleeding volume, followed by gelatin sponge and cellulose membrane.

Imaging features of a gelatin-thrombin matrix hemostatic agent in the intracranial surgical bed: a unique space-occupying pseudomass

BACKGROUND AND PURPOSE

Absorbable gelatin-thrombin matrix is increasingly being used in neurosurgical procedures; unlike other hemostats, the stable matrix is left undisturbed and fills the surgical bed after achieving hemostasis. We investigated the immediate postoperative radiographic imaging appearance of the gelatin-thrombin matrix in intracranial operative beds.

MATERIALS AND METHODS

Thirty-one consecutive patients (18 men, 13 women; mean age, 59 years) with 34 surgical cavities, had 31 brain MRIs and 9 head CTs performed ≤ 48 hours postoperatively. They were retrospectively reviewed. Images were evaluated independently by 2 neuroradiologists blinded to the surgical techniques. Surgical beds were evaluated for the presence of the gelatin-thrombin matrix, which appeared as pseudoair material (Hounsfield units ≤ -100) on CT, had characteristic T2-hypointense speckles in a T2-hyperintense background, and demonstrated complete gradient-recalled echo hypointensity on MR imaging. To determine the diagnostic performance of imaging features for the detection of the gelatin-thrombin matrix, the Fisher exact test for the association between imaging features and the presence of the gelatin-thrombin matrix and κ analysis for interobserver agreement were performed.

RESULTS

Hemostasis was achieved with standard methods in 12 surgical beds and with the gelatin-thrombin matrix in 22 beds. Interobserver agreement was substantial. The gelatin-thrombin matrix demonstrated pseudoair hypoattenuation (88% sensitivity, 100% specificity, 90% accuracy; P = .067, κ = 0.74) and distinctive T2-hypointense speckles in a background of T2-hyperintensity (81% sensitivity, 85% specificity, 82% accuracy; P = <.001, κ = 0.76). Combined characteristic T2 speckles and gradient-recalled echo hypointensity increased the specificity (81% sensitivity, 100% specificity, 88% accuracy; P = < .001).

CONCLUSIONS

The unique appearance (pseudoair on CT, T2 speckles with gradient-recalled echo hypointensity) of the gelatin-thrombin matrix should not be mistaken for gossypiboma, pneumocephalus, and/or hematoma.

The efficacy and safety of chitosan dextran gel in a burr hole neurosurgical sheep model

BACKGROUND

Achieving and maintaining haemostasis is of paramount importance in neurosurgery. Chitosan has been shown in both animal and human models to be significantly effective in haemostasis as well as in reducing adhesion formation.

OBJECTIVES

To evaluate the haemostatic potential and to study histopathological changes caused by novel chitosan dextran gel in a neurosurgical sheep model.

METHOD

Ten sheep underwent neurosurgical burr hole procedure. Bleeding control was tested at the level of bone, dura and brain separately with both chitosan gel and Gelfoam paste on separate burr holes. Baseline bleeding was measured at the time of injury using the Boezaart scale, and then every 2 min after the application of each agent until complete haemostasis or 10 min, whichever was earlier. Safety was assessed through MRI scans and histopathological analysis.

RESULTS

Mixed modeling showed no statistical difference in time to haemostasis between chitosan gel and Gelfoam paste (means of log-normalized areas under the curve were 1.3688 and 1.3196 respectively) for each burr hole (p = 0.7768). Logistic regression modeling showed that Chitosan significantly decreased the incidence of bleeding beyond the first time point measured after application of the treatment when compared to Gelfoam (OR = 2.7, p = 0.04). Average edema volume (cm(3)) on post-operative MRI was 0.97 for Gelfoam and 1.11 for (p = 0.49) while average histology scores were 2.5 for Gelfoam versus 3.3 for chitosan (p = 0.32).

CONCLUSION

Chitosan dextran gel is an effective haemostatic agent to control bleeding in brain tissue. It is safe and nontoxic to neural tissue.

On the value of routine prothrombin time screening in elective neurosurgical procedures

Object

The authors performed a study to evaluate whether preoperative assessment of prothrombin time (PT) is mandatory in patients undergoing routinely planned neurosurgical procedures.

Methods

The charts of all patients admitted to general wards of the authors' department for routinely planned surgery (excluding trauma and ICU patients) between 2006 and 2010 were retrospectively reviewed. The authors assessed preoperative PT and the clinical courses of all patients, with special consideration for patients receiving coagulation factor substitution. All cases involving hemorrhagic complications were analyzed in detail with regard to pre- and postoperative PT abnormalities. Prothrombin time was expressed as the international normalized ratio, and values greater than 1.28 were regarded as elevated.

Results

Clinical courses and PT values of 4310 patients were reviewed. Of these, 33 patients (0.7%) suffered hemorrhagic complications requiring repeat surgery. Thirty-one patients (94%) had a normal PT before the initial operation, while 2 patients had slightly elevated PT values of 1.33 and 1.65, which were anticipated based on the patient's history. In the latter 2 cases, surgery was performed without prior correction of PT. Preoperatively, PT was elevated in 78 patients (1.8%). In 73 (93.6%) of the 78 patients, the PT elevation was expected and explained by each patient's medical history. In only 5 (0.1%) of 4310 patients did we find an unexpected PT elevation (mean 1.53, range 1.37–1.74). All 5 patients underwent surgery without complications, while 2 had received coagulation factor substitution preoperatively, as requested by the surgeon, because of an estimated risk of bleeding complications. None of the 5 patients received coagulation factor substitution postoperatively, and later detailed laboratory studies ruled out single coagulation factor deficiencies. There was no statistically significant association between preoperatively elevated PT levels and the occurrence of hemorrhagic complications (p = 0.12). Before the second procedure but not before the initial operation, 4 (12%) of the 33 patients had elevated PT.

Conclusions

The findings suggest that the value of preoperative PT testing is limited in patients in whom a normal history can be ascertained. Close postoperative PT control is necessary in every neurosurgical patient, and better tests need to be developed to identify patients who are prone to hemorrhagic complications.

Low-grade CSF leaks in endoscopic trans-sphenoidal pituitary surgery: efficacy of a simple and fully synthetic repair with a hydrogel sealant

BACKGROUND

Intra-operative CSF leak during endoscopic trans-sphenoidal surgery is not uncommon. Surgical repair with a variety of autologous grafts, rigid buttresses and CSF diversion techniques that add time and complexity have been reported.

OBJECTIVE

To describe a simple and purely synthetic closure for low-grade CSF leaks following endoscopic trans-sphenoidal pituitary surgery.

METHODS

A retrospective review of all endoscopic trans-sphenoidal surgery undertaken for pituitary pathology between 2005 and 2010 was carried out. The grade of CSF leak and success of graded repair was noted. Patients with no CSF leak (grade 0) had gelatin sponge placed in the tumour cavity. In those with low-grade CSF leak through small arachnoid defects (grade 1), repair was carried out using gelatin sponge and hydrogel sealant overlay. CSF diversion was not employed for low-grade CSF leaks.

RESULTS

Of the 255 endoscopic trans-sphenoidal surgeries, 158 (62%) had no leak (grade 0) and 74 (29%) had a low-grade leak (grade 1). Repairs in all cases were of grade 0, and all but two cases of grade 1 CSF leak were successful at a mean follow-up of 29 months. The 2 (2.7%) post-operative CSF leaks were seen within 6 weeks of surgery. Both cases were related to bouts of sneezing and were repaired using further trans-sphenoidal surgery and/or lumbar CSF diversion.

CONCLUSIONS

A simple purely synthetic repair of low-grade CSF leaks is described. This repair is safe and comparable in efficacy whilst avoiding the morbidity related to more complex sellar reconstructions previously described.

Use of a thrombin-gelatin haemostatic matrix in endoscopic endonasal extended approaches: technical note

OBJECTIVE

The management of intradural bleeding during extended endoscopic endonasal surgery is challenging. This technical note describes the use of a biological haemostatic agent which could be useful when other established strategies and materials are not effective.

MATERIALS AND METHODS

From January 2004 to January 2008, 65 consecutive patients underwent extended endoscopic endonasal interventions. Of these, 29 procedures required the application of a thrombin-gelatin haemostatic matrix. We reviewed the patients' operative records to determine the source, type of bleeding and haemostatic strategy.

RESULTS

We analysed bleedings from the venous sinuses, arteries, tumour bed and internal carotid artery and observed complete haemostasis immediately after application of FloSeal. The matrix was useful for both oozing and focal haemorrhage and effective even for high-flow bleeding. Only bleeding from an internal carotid artery tear required a second application.

CONCLUSION

The thrombin-gelatin matrix could represent a valuable tool when other haemostatic strategies are ineffective or suboptimal. It is safe and biocompatible when compared with haemostatic agents currently in use.