A Randomized Prospective Multicenter Trial of a Novel Vascular Sealant

The role of sealants for achieving anastomotic hemostasis in vascular surgery

BACKGROUND

During vascular interventions, connections that link arteries, veins, or synthetic grafts, which are known as an 'anastomosis', may be necessary. Vascular anastomoses can bleed from the needle holes that result from the creation of the anastomoses. Various surgical options are available for achieving hemostasis, or the stopping of bleeding, including the application of sealants directly onto the bleeding vessels or tissues. Sealants are designed for use in vascular surgery as adjuncts when conventional interventions are ineffective and are applied directly by the surgeon to seal bleeding anastomoses. Despite the availability of several different types of sealants, the evidence for the clinical efficacy of these hemostatic adjuncts has not been definitively established in vascular surgery patients.

OBJECTIVES

To evaluate the benefits and harms of sealants as adjuncts for achieving anastomotic site hemostasis in patients undergoing vascular surgery.

SEARCH METHODS

The Cochrane Vascular Information Specialist conducted systematic searches of the following databases: the Cochrane Vascular Specialised Register via the Cochrane Register of Studies; the Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE via Ovid; Embase via Ovid ; and CINAHL via EBSCO. We also searched ClinicalTrials.gov and the WHO International Clinical Trials Registry Platform for clinical trials. Reference lists of included trials and relevant reviews were also searched. The latest search date was 6 March 2023.

SELECTION CRITERIA

We included randomized controlled trials that compared fibrin or synthetic sealant use with alternative interventions (e.g. manual compression, reversal of anticoagulation) for achieving anastomotic-site hemostasis in vascular surgery procedures. We included participants who underwent the creation of an anastomosis during vascular surgery. We excluded non-vascular surgery patients.

DATA COLLECTION AND ANALYSIS

We have used standard Cochrane methods. Our primary outcomes were time to hemostasis, failure of hemostatic intervention, and intraoperative blood loss. Our secondary outcomes were operating time, death from bleeding complications up to 30 days, postoperative bleeding up to 30 days, unplanned return to the operating room for bleeding complications management up to 30 days, quality of life, and adverse events. We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We found 24 randomized controlled trials that included a total of 2376 participants who met the inclusion criteria. All trials compared sealant use with standard care controls, including oxidized cellulose, gelatin sponge, and manual compression. All trials were at high risk of performance bias, detection bias, and other sources of bias. We downgraded the certainty of evidence for risk of bias concerns, inconsistency, imprecision and possible publication bias. Combining data on time to hemostasis showed that sealant use may reduce the mean time to hemostasis compared to control (mean difference (MD) -230.09 seconds, 95% confidence interval (CI) -329.24 to -130.94; P < 0.00001; 7 studies, 498 participants; low-certainty evidence). Combining data on failure of hemostatic intervention showed that sealant use may reduce the rate of failure compared to control, but the evidence is very uncertain (risk ratio (RR) 0.46, 95% CI 0.35 to 0.61; P < 0.00001; 17 studies, 2120 participants; very low-certainty evidence). We did not detect any clear differences between the sealant and control groups for intraoperative blood loss (MD -32.69 mL, 95% CI -96.21 to 30.83; P = 0.31; 3 studies, 266 participants; low-certainty evidence); operating time (MD -18.72 minutes, 95% CI -40.18 to 2.73; P = 0.09; 4 studies, 436 participants; low-certainty evidence); postoperative bleeding (RR 0.78, 95% CI 0.59 to 1.04; P = 0.09; 9 studies, 1216 participants; low-certainty evidence), or unplanned return to the operating room (RR 0.27, 95% CI 0.04 to 1.69; P = 0.16; 8 studies, 721 participants; low-certainty evidence). No studies reported death from bleeding or quality of life outcomes.

AUTHORS' CONCLUSIONS

Based on meta-analysis of 24 trials with 2376 participants, our review demonstrated that sealant use for achieving anastomotic hemostasis in vascular surgery patients may result in reduced time to hemostasis, and may reduce rates of hemostatic intervention failure, although the evidence is very uncertain, when compared to standard controls. Our analysis showed there may be no differences in intraoperative blood loss, operating time, postoperative bleeding up to 30 days, and unplanned return to the operating room for bleeding complications up to 30 days. Deaths and quality of life could not be analyzed. Limitations include the risk of bias in all studies. Our review has demonstrated that using sealants may reduce the time required to achieve hemostasis and the rate of hemostatic failure. However, a significant risk of bias was identified in the included studies, and future trials are needed to provide unbiased data and address other considerations such as cost-effectiveness and adverse events with sealant use.

TAVAC: comprehensive review of currently available hemostatic products as adjunct to surgical hemostasis

BACKGROUND

The use of hemostatic agents by general surgeons during abdominal operations is commonplace as an adjunctive measure to minimize risks of postoperative bleeding and its downstream complications. Proper selection of products can be hampered by marginal understanding of their pharmacokinetics and pharmacodynamics. While a variety of hemostatic agents are currently available on the market, the choice of those products is often confusing for surgeons. This paper aims to summarize and compare the available hemostatic products for each clinical indication and to ultimately better guide surgeons in the selection and proper use of hemostatic agents in daily clinical practice.

METHODS

We utilized PubMed electronic database and published product information from the respective pharmaceutical companies to collect information on the characteristics of the hemostatic products.

RESULTS

All commercially available hemostatic agents in the US are described with a description of their mechanism of action, indications, contraindications, circumstances in which they are best utilized, and expected results.

CONCLUSION

Hemostatic products come with many different types and specifications. They are valuable tools to serve as an adjunct to surgical hemostasis. Proper education and knowledge of their characteristics are important for the selection of the right agent and optimal utilization.

Drugs to reduce bleeding and transfusion in major open vascular or endovascular surgery: a systematic review and network meta-analysis

BACKGROUND

Vascular surgery may be followed by internal bleeding due to inadequate surgical haemostasis, abnormal clotting, or surgical complications. Bleeding ranges from minor, with no transfusion requirement, to massive, requiring multiple blood product transfusions. There are a number of drugs, given systemically or applied locally, which may reduce the need for blood transfusion.

OBJECTIVES

To assess the effectiveness and safety of anti-fibrinolytic and haemostatic drugs and agents in reducing bleeding and the need for blood transfusion in people undergoing major vascular surgery or vascular procedures with a risk of moderate or severe (> 500 mL) blood loss.

SEARCH METHODS

We searched: Cochrane Central Register of Controlled Trials; MEDLINE; Embase; CINAHL, and Transfusion Evidence Library. We also searched the WHO ICTRP and ClinicalTrials.gov trial registries for ongoing and unpublished trials. Searches used a combination of MeSH and free text terms from database inception to 31 March 2022, without restriction on language or publication status.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) in adults of drug treatments to reduce bleeding due to major vascular surgery or vascular procedures with a risk of moderate or severe blood loss, which used placebo, usual care or another drug regimen as control.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were units of red cells transfused and all-cause mortality. Our secondary outcomes included risk of receiving an allogeneic blood product, risk of reoperation or repeat procedure due to bleeding, risk of a thromboembolic event, risk of a serious adverse event and length of hospital stay. We used GRADE to assess certainty of evidence.

MAIN RESULTS

We included 22 RCTs with 3393 participants analysed, of which one RCT with 69 participants was reported only in abstract form, with no usable data. Seven RCTs evaluated systemic drug treatments (three aprotinin, two desmopressin, two tranexamic acid) and 15 RCTs evaluated topical drug treatments (drug-containing bioabsorbable dressings or glues), including fibrin, thrombin, collagen, gelatin, synthetic sealants and one investigational new agent. Most trials were conducted in high-income countries and the majority of the trials only included participants undergoing elective surgery. We also identified two ongoing RCTs. We were unable to perform the planned network meta-analysis due to the sparse reporting of outcomes relevant to this review. Systemic drug treatments We identified seven trials of three systemic drugs: aprotinin, desmopressin and tranexamic acid, all with placebo controls. The trials of aprotinin and desmopressin were small with very low-certainty evidence for all of our outcomes. Tranexamic acid versus placebo was the systemic drug comparison with the largest number of participants (2 trials; 1460 participants), both at low risk of bias. The largest of these included a total of 9535 individuals undergoing a number of different higher risk surgeries and reported limited information on the vascular subgroup (1399 participants). Neither trial reported the number of units of red cells transfused per participant up to 30 days. Three outcomes were associated with very low-certainty evidence due to the very wide confidence intervals (CIs) resulting from small study sizes and low number of events. These were: all-cause mortality up to 30 days; number of participants requiring an allogeneic blood transfusion up to 30 days; and risk of requiring a repeat procedure or operation due to bleeding. Tranexamic acid may have no effect on the risk of thromboembolic events up to 30 days (risk ratio (RR) 1.10, 95% CI 0.88 to 1.36; 1 trial, 1360 participants; low-certainty evidence due to imprecision). There is one large ongoing trial (8320 participants) comparing tranexamic acid versus placebo in people undergoing non-cardiac surgery who are at high risk of requiring a red cell transfusion. This aims to complete recruitment in April 2023. This trial has primary outcomes of proportion of participants transfused with red blood cells and incidence of venous thromboembolism (DVT or PE). Topical drug treatments Most trials of topical drug treatments were at high risk of bias due to their open-label design (compared with usual care, or liquids were compared with sponges). All of the trials were small, most were very small, and few reported clinically relevant outcomes in the postoperative period. Fibrin sealant versus usual care was the topical drug comparison with the largest number of participants (5 trials, 784 participants). The five trials that compared fibrin sealant with usual care were all at high risk of bias, due to the open-label trial design with no measures put in place to minimise reporting bias. All of the trials were funded by pharmaceutical companies. None of the five trials reported the number of red cells transfused per participant up to 30 days or the number of participants requiring an allogeneic blood transfusion up to 30 days. The other three outcomes were associated with very low-certainty evidence with wide confidence intervals due to small sample sizes and the low number of events, these were: all-cause mortality up to 30 days; risk of requiring a repeat procedure due to bleeding; and risk of thromboembolic disease up to 30 days. We identified one large trial (500 participants) comparing fibrin sealant versus usual care in participants undergoing abdominal aortic aneurysm repair, which has not yet started recruitment. This trial lists death due to arterial disease and reintervention rates as primary outcomes.

AUTHORS' CONCLUSIONS

Because of a lack of data, we are uncertain whether any systemic or topical treatments used to reduce bleeding due to major vascular surgery have an effect on: all-cause mortality up to 30 days; risk of requiring a repeat procedure or operation due to bleeding; number of red cells transfused per participant up to 30 days or the number of participants requiring an allogeneic blood transfusion up to 30 days. There may be no effect of tranexamic acid on the risk of thromboembolic events up to 30 days, this is important as there has been concern that this risk may be increased. Trials with sample size targets of thousands of participants and clinically relevant outcomes are needed, and we look forward to seeing the results of the ongoing trials in the future.

Polymeric Tissue Adhesives

Polymeric tissue adhesives provide versatile materials for wound management and are widely used in a variety of medical settings ranging from minor to life-threatening tissue injuries. Compared to the traditional methods of wound closure (i.e., suturing and stapling), they are relatively easy to use, enable rapid application, and introduce minimal tissue damage. Furthermore, they can act as hemostats to control bleeding and provide a tissue-healing environment at the wound site. Despite their numerous current applications, tissue adhesives still face several limitations and unresolved challenges (e.g., weak adhesion strength and poor mechanical properties) that limit their use, leaving ample room for future improvements. Successful development of next-generation adhesives will likely require a holistic understanding of the chemical and physical properties of the tissue-adhesive interface, fundamental mechanisms of tissue adhesion, and requirements for specific clinical applications. In this review, we discuss a set of rational guidelines for design of adhesives, recent progress in the field along with examples of commercially available adhesives and those under development, tissue-specific considerations, and finally potential functions for future adhesives. Advances in tissue adhesives will open new avenues for wound care and potentially provide potent therapeutics for various medical applications.

Meta-analysis of the use of surgical sealants for suture-hole bleeding in arterial anastomoses

BACKGROUND

Suture-hole bleeding in arterial anastomoses prolongs operating time and increases blood loss, particularly with the use of prosthetic grafts. Surgical sealants (such as fibrin) may be used as haemostatic adjuncts in vascular surgery. This is a systematic review and meta-analysis of published studies that investigated the utility of surgical sealants in arterial-to-prosthetic graft anastomoses.

METHODS

A systematic review was undertaken of papers published until January 2015 on Embase, MEDLINE, PubMed, PubMed Central and Cochrane databases that analysed the use of surgical sealants as haemostatic adjuncts after arterial anastomoses. RCTs were included, with study endpoints of time to haemostasis or haemostasis at 5 min. Secondary outcomes included treatment failure, mean difference in estimated blood loss and duration of surgery. Sensitivity and subgroup analyses were performed, as well as funnel plot analysis for publication bias.

RESULTS

A total of 2513 citations were reviewed; 19 RCTs comprising 1560 patients were ultimately included in the analysis. The majority of studies compared fibrin sealant with control haemostatic measures. Pooled analysis suggested that surgical sealants reduced the time to haemostasis (mean difference 243·26 (95 per cent c.i. 183·99 to 302·53) s; P < 0·001), improved haemostasis at 5 min (odds ratio 4·50, 95 per cent c.i. 2·59 to 7·81; P < 0·001), and were associated with less treatment failure, blood loss and shorter duration of surgery.

CONCLUSION

Surgical sealants appear to reduce suture-hole bleeding significantly in vascular prosthetic graft anastomoses compared with standard haemostatic measures.

Results from a First-in-Human Trial of a Novel Vascular Sealant

Background

Suture hole bleeding from synthetic grafts presents a hemostatic challenge. The designs of many vascular sealants are not optimal (non-adherence to wet surfaces, excessive swelling, inflexible). PreveLeak™ (formerly ArterX^®) is a polyaldehyde–bovine serum albumin-based sealant whose efficacy, safety, and performance were evaluated in this first-in-human study.

Materials and methods

A prospective, single-arm, multicenter study was performed in patients undergoing open vascular reconstructions with prosthetic grafts. Sealant was applied to the suture line after completion of the anastomosis. The primary endpoint was the incidence of immediate sealing (without clinically significant bleeding) upon clamp release. Secondary endpoints were time to sealing, safety, and assessment of product performance.

Results

Fifty-six anastomoses were performed in 32 patients. Grafts were Dacron (66% of sites), polytetrafluoroethylene (PTFE; 32%), or both Dacron and PTFE (2%). The femoral artery was the most common site of anastomosis (41% of sites). Immediate sealing after clamp release was achieved at all anastomoses (100%); 93% had no bleeding and 7% had oozing. No rebleeding occurred during 10 min of observation. The three most common adverse events were graft or bypass occlusion (n = 5 patients), infection (n = 4), and seroma (n = 3); none were device related. The sealant was considered easy to apply, quickly forming a soft gel, and adhering to tissue and grafts.

Conclusion

PreveLeak effectively sealed anastomotic suture lines during vascular reconstruction procedures and was considered easy to use. Adverse events were consistent with those commonly observed in patients undergoing surgical procedures. These results provided the support for conducting a larger controlled clinical trial.

Clinical applications of surgical adhesives and sealants

In the United States and Europe, the number of topical adhesives, surgical sealants, and hemostats approved for use in the surgical setting is ever expanding although no single device fills all medical and surgical needs to replace sutures. As more surgical procedures are performed through laparoscopic and robotic approaches, these devices are becoming more important, and current research is focused on solving the limitations of conventional wound treatments. This review article discusses clinical applications of various biologically derived and synthetic products that are currently available to surgeons and those that are in development.