Prevention of air leakage by spraying vivostat fibrin sealant after lung resection in pigs

Characterisation of pulmonary air leak measurements using a mechanical ventilator in a bench setup

Prolonged air leakage (AL) following pulmonary resections leads to prolonged hospital stay and post-operative complications. Intra- and postoperative quantification of AL might be useful for improving treatment decisions, but these measurements have not been characterised. AL calculations based on inspiratory and expiratory tidal volumes were investigated in an Intensive Care Unit mechanical ventilator circuit (Servo-I). AL was also measured by a digital chest drainage system. This study shows that AL measurements increase in accuracy when corrected for baseline deviations (R: 0.904 > 0.997, p < 0.001). Bland-Altman analysis revealed a funnel-shape, indicative of a detection threshhold. Corrected measurements were most accurate when averaged over five breaths and AL was >500 mL/min, with an estimated mean systemic bias of 7.4% (95%-limits of agreement [LoA]: 1.1%-13.7%) at 500 mL/min air leak. Breath-by-breath analysis showed most accurate results at AL >20 mL/breath (R: 0.989-0.991, p < 0.001) at tidal volumes between 350-600 mL. The digital drain had a mean systemic bias of -11.1% (95%-LoA: -18.9% to -3.3%) with homogenous scatter in Bland-Altman analysis and a strong correlation to the control measurement over a large range (0-2000mL/min, R: 0.999, p < 0.001). This study indicates that the Servo-I can be used for air leak quantification in clinically relevant ranges (>500 mL/min), but is unsuited for small leak detection due to a detection threshold. Researchers and clinicians should be aware of varying accuracy and interoperability characteristics between AL measurement devices.

Proof-of-principle of a lung sealant based on functionalized polyoxazolines: experiments in an ovine acute aerostasis model

OBJECTIVES

More effective lung sealants are needed to prevent prolonged pulmonary air leakage (AL). Polyoxazoline-impregnated gelatin patch (N-hydroxysuccinimide ester functionalized poly(2-oxazoline)s; NHS-POx) was promising for lung sealing ex vivo. The aim of this study is to confirm sealing effectiveness in an in vivo model of lung injury.

METHODS

An acute aerostasis model was used in healthy adult female sheep, involving bilateral thoracotomy, amputation lesions (bronchioles Ø > 1.5 mm), sealant application, digital chest tube for monitoring AL, spontaneous ventilation, obduction and bursting pressure measurement. Two experiments were performed: (i) 3 sheep with 2 lesions per lung (N = 4 NHS-POx double-layer, N = 4 NHS-POx single-layer, N = 4 untreated) and (ii) 3 with 1 lesion per lung (N = 3 NHS-POx single-layer, N = 3 untreated). In pooled linear regression, AL was analysed per lung (N = 7 NHS-POx, N = 5 untreated) and bursting pressure per lesion (N = 11 NHS-POx, N = 7 untreated).

RESULTS

Baseline AL was similar between groups (mean 1.38-1.47 l/min, P = 0.90). NHS-POx achieved sealing in 1 attempt in 8/11 (72.7%) and in 10/11 (90.9%) in >1 attempt. Application failures were only observed on triangular lesions requiring 3 folds around the lung. No influences of methodological variation between experiments was detected in linear regression (P > 0.9). AL over initial 3 h of drainage was significantly reduced for NHS-POx [median: 7 ml/min, length of interquartile range: 333 ml/min] versus untreated lesions (367 ml/min, length of interquartile range: 680 ml/min, P = 0.036). Bursting pressure was higher for NHS-POx (mean: 33, SD: 16 cmH2O) versus untreated lesions (mean: 19, SD: 15 cmH2O, P = 0.081).

CONCLUSIONS

NHS-POx was effective for reducing early AL, and a trend was seen for improvement of bursting strength of the covered defect. Results were affected by application characteristics and lesion geometry.

New Infiltration Technique in the Treatment of the Plantar Fascia Syndrome Based on Platelet-Rich Plasma

Pain in the attachment of the plantar fascia in the calcaneus represents 10% of all sports injuries, affects 10% of foot runners, and will affect around 20% of the world population. There is no effective conservative treatment for it. This paper justifies a new definition and name for this pathology, Plantar Fascia Syndrome (PFS), presents a methodology for its diagnosis, and presents the clinical and functional effectiveness of a new conservative treatment based on platelet-rich plasma (PRP). In total, 25 patients (from an initial sample of 260) diagnosed with recalcitrant PFS lasting for more than 12 months were treated with a single infiltration of 2 mL of PRP, according to a new technic proposed. The study was approved by the ethical committee for clinical research of the reference hospital. The patients were controlled after 15, 30, 90, and 180 days, reviewing on each occasion pain, thickness of the plantar fascia, and active extension of the ankle joint. A total of 15 days after infiltration, 85% of patients had no clinical signs requiring treatment. After 90 days of infiltration, no patients showed clinical signs. This improvement in the patients' condition lasted for 180 days. All patients after treatment can fully resume normal activity with no pain.

Novel method for the generation of tissue-engineered vascular grafts based on a highly compacted fibrin matrix

The generation of tissue-engineered blood vessel substitutes remains an ongoing challenge for cardiovascular tissue engineering. Full biocompatibility and immediate availability have emerged as central issues for clinical use. To address these issues, we developed a technique that allows the generation of highly stable tubular fibrin segments. The process is based on the compaction of fibrin in a custom-made high-speed rotation mold. In an automated process, fibrin is precipitated from plasma by means of the Vivostat® system. Following application to the rotating mold, the fibrin was compacted by centrifugal force and excess fluid was pressed out. This compaction results in increasing cross-links between the fibrin fibrils and a corresponding significant increase of biomechanical stability up to a burst strength of 230mm of mercury. The molding process allows for a simultaneous seeding procedure. In a first in vivo evaluation in a sheep model, segments of the carotid artery were replaced by tissue-engineered vascular grafts, generated immediately prior to implantation (n=6). Following subjection to the body's remodeling mechanisms, the segments showed a high structural similarity to a native artery after explantation at 6months. Thus, this technique may represent a powerful tool for the generation of biomechanically stable vascular grafts immediately prior to implantation.

STATEMENT OF SIGNIFICANCE

Fibrin has previously been shown to be suitable as a matrix for the seeding of different celltypes and for that reason was widely used as scaffold in different fields of tissue engineering. Nevertheless, fibrin's lack of stability has strongly limited its application. Our study describes a novel moulding technique for the generation of a highly compacted fibrin matrix. Using this approach, it was possible to optimize the engineering process of tubular fibrin segments to provide bioartificial vascular grafts within one hour with sufficient stability for immediate implantation in the arterial system. Thus, this technique may represent a powerful tool to get closer to the ultimate aim of an optimal bioartificial vascular graft.

Autologous fibrin sealant (Vivostat(®)) in the neurosurgical practice: Part I: Intracranial surgical procedure

Background:

Hemorrhages, cerebrospinal fluid (CSF) fistula and infections are the most challenging postoperative complications in Neurosurgery. In this study, we report our preliminary results using a fully autologous fibrin sealant agent, the Vivostat^® system, in achieving hemostasis and CSF leakage repair during cranio-cerebral procedures.

Methods:

From January 2012 to March 2014, 77 patients were studied prospectively and data were collected and analyzed. Autologous fibrin sealant, taken from patient's blood, was prepared with the Vivostat^® system and applied on the resection bed or above the dura mater to achieve hemostasis and dural sealing. The surgical technique, time to bleeding control and associated complications were recorded.

Results:

A total of 79 neurosurgical procedures have been performed on 77 patients. In the majority of cases (98%) the same autologous fibrin glue provided rapid hemostasis and dural sealing. No patient developed allergic reactions or systemic complications in association with its application. There were no cases of cerebral hematoma, swelling, infection, or epileptic seizures after surgery whether in the immediate or in late period follow-up.

Conclusions:

In this preliminary study, the easy and direct application of autologous fibrin sealant agent helped in controlling cerebral bleeding and in providing prompt and efficient dural sealing with resolution of CSF leaks. Although the use of autologous fibrin glue seems to be safe, easy, and effective, further investigations are strongly recommended to quantify real advantages and potential limitations.

The experimental use of N-butyl cyanoacrylate tissue adhesive in pulmonary wedge resections

BACKGROUND

In this experimental study, the effectiveness of N-butyl cyanoacrylate tissue adhesive on preventing air leakage after pulmonary wedge resection was observed.

METHODS

Twenty pairs of sheep lungs were used. Before initiating the study, the sheep lungs were ventilated to identify any air leakage from the parenchyma. On positive results, those sheep lungs were then excluded from the study. Wedge resection was performed on the right and left lower lobes of sheep lungs by clamping the edges forming a triangle of 5 cm × 5 cm × 5 cm. One side of parenchyma was sutured by 3/0 vicryl (Group A) while the other side of parenchyma was sealed by N-butyl cyanoacrylate (Group B). After waiting for 5 min for N-butyl cyanoacrylate to dry, the sheep lungs were intubated by 6F endotracheal tubes. The lungs were soaked in a bath tub filled with 10 cm deep water and inflated by 40 mmHg pressure to record any air leakage from the parenchyma partially sutured by vicryl and sealed by N-butyl cyanoacrylate.

RESULTS

Air leakages were observed on the parenchyma surfaces of group of lungs (100%) sutured by vicryl (minimal 30%, mild 50% or massive 20% levels), while only on four of (20%) the other group of lungs sealed by N-butyl cyanoacrylate, minimal air leakage was observed on the parenchymal surface. There was an extremely significant difference between Group A and Group B in terms of the development of air leakage (p=000).

CONCLUSION

We consider that, N-butyl cyanoacrylate could be used effectively and safely to prevent air leakage from the pulmonary wedge resection surface.

Surgical sealant for preventing air leaks after pulmonary resections in patients with lung cancer

BACKGROUND

Postoperative air leak is a frequent complication after pulmonary resection for lung cancer. It may cause serious complications, such as empyema, or prolong the need for chest tube and hospitalization. Different types of surgical sealants have been developed to prevent or to reduce postoperative air leaks. A systematic review was therefore undertaken to evaluate the evidence on their effectiveness.

OBJECTIVES

To evaluate the effectiveness of surgical sealants in preventing or reducing postoperative air leaks after pulmonary resection for lung cancer.

SEARCH STRATEGY

We searched the electronic databases MEDLINE (1966 to September 2008), EMBASE (1974 to September 2008), and the Cochrane Central Register of Controlled Trials (CENTRAL)(The Cochrane Library, Issue 3, 2008) and listed references. We hand searched conference proceedings to identify published and unpublished trials.

SELECTION CRITERIA

We included randomized controlled clinical trials in which standard closure techniques plus a sealant were compared with the same intervention with no use of any sealant in patients undergoing elective pulmonary resection provided that a large proportion of the patients studied had undergone pulmonary resection for lung cancer.

DATA COLLECTION AND ANALYSIS

Four reviewers independently selected the trials to be included in the review, assessed methodological quality of each trial and extracted data using a standardized form. Because of several limitations, narrative synthesis was used at this stage.

MAIN RESULTS

Sixteen trials, with 1642 randomized patients in total were included. In thirteen trials there were differences between treatment and control patients in reducing postoperative air leaks. This reduction proved to be significant in six trials. Three trials showed a significant reduction in time to chest drain removal in the treatment group. In two trials, the percentage of patients with persistent air leak was significantly smaller in the treatment group. Finally, three trials including 352 patients showed a statistically significant reduction in length of hospital stay.

AUTHORS' CONCLUSIONS

Surgical sealants reduce postoperative air leaks and time to chest drain removal but this reduction is not always associated with a reduction in length of postoperative hospital stay. Therefore, systematic use of surgical sealants with the objective of reducing hospital stay cannot be recommended at the moment. More and larger randomized controlled clinical trials are needed.

Autologous fibrin sealant reduces the incidence of prolonged air leak and duration of chest tube drainage after lung volume reduction surgery: a prospective randomized blinded study

OBJECTIVE

Prolonged air leak is reported in up to 50% of patients after lung volume reduction surgery. The effect of an autologous fibrin sealant on the intensity and duration of air leak and on the time to chest drain removal after lung volume reduction surgery was investigated in a randomized prospective clinical trial.

METHODS

Twenty-five patients underwent bilateral thoracoscopic lung volume reduction surgery. In each patient, an autologous fibrin sealant was applied along the staple lines on one side, whereas no additional measure was taken on the other side. Randomization of treatment was performed at the end of the resection on the first side. Air leak was assessed semiquantitatively by use of a severity score (0 = no leak; 4 = continuous severe leak) by two investigators blinded to the treatment.

RESULT

Mean value of the total severity scores for the first 48 hours postoperative was significantly lower in the treated group (4.7 +/- 7.7) than in the control group (16.0 +/- 10.1) (P < .001), independently of the length of the resection. Prolonged air leak and mean duration of drainage were also significantly reduced after application of the sealant (4.5% and 2.8 +/- 1.9 days versus 31.8% and 5.9 +/- 2.9 days) (P = .03 and P < .001).

CONCLUSIONS

Autologous fibrin sealant for reinforcement of the staple lines after lung volume reduction surgery significantly reduces prolonged air leak and duration of chest tube drainage.

Development of new biodegradable hydrogel glue for preventing alveolar air leakage

OBJECTIVE

Air leakage is a frequent complication during lung surgery. A new hydrogel glue was created by mixing aldehyded dextran and epsilon-poly(l-lysine), and its feasibility as a surgical sealant was evaluated in comparison with that of conventional fibrin glue.

METHODS

Bursting pressure after application of each glue to 30 x 30-mm pleuroparenchymal defects was evaluated in two groups of 14 beagle dogs. Biodegradability and histotoxicity of the glues were evaluated in another 6 dogs with 15-mm circular pleuroparenchymal defects. Adhesions, infections, and histologic changes were observed on scheduled days for 6 months.

RESULTS

The mean bursting pressure after application was 38.4 +/- 4.6 cm H2O for the new glue and 32.1 +/- 4.5 cm H2O for fibrin glue (P = .02), the former providing more effective sealing of pulmonary air leakage than the latter. Macroscopically, no adhesions or infections were observed in areas of glue application. About 90% of the new glue degraded within 3 months, but complete disappearance was not observed by 6 months. On the other hand, the fibrin glue was replaced by white pleural tissue at 4 weeks. Histologically, the new glue was covered by one layer of mesothelial cells at 2 weeks and completely covered by thick fibrous tissue at 4 weeks. Inflammatory reaction was minimal around the residual glue after 3 months. Although the new glue degraded more slowly than did the fibrin glue, the biocompatibility of the new glue was sufficient for clinical use.

CONCLUSION

Our new hydrogel glue demonstrates a strong sealing effect, with good biocompatibility, and has potential usefulness as an adhesive in lung surgery.

Creation of a uniform pleural defect model for the study of lung sealants

OBJECTIVE

Animal models are indispensable for the development of new therapeutic methods for the closure of alveolar air leakage. However, it is difficult to create a uniform pleural defect model. The purpose of this study was to establish an appropriate animal model for assessing the efficacy and histotoxicity of synthetic sealants for lung surgery.

METHODS

Nine beagle dogs were used to evaluate the pleural defect model in comparison with conventional resection procedures. A donut-shaped silicon ring with an inner diameter of 15 mm was placed on the pleura, and 0.1 mL of cyanoacrylate was dropped into the ring. A pleural defect was created by sliding a microtome blade just beneath the polymerized cyanoacrylate. Hemostasis was performed by pressure with a sponge.

RESULTS

Morphologically, round areas of the pleura were uniformly resected with our procedure. The resected tissue consisted of pleura and thin underlying lung parenchyma. Among the results from 3 surgeons, there were no significant differences in the mean time required for hemostasis (P = .69), the mean thickness of the resected tissue (P = .13), and the mean amount of air leakage from the resected area (P = .19). No penetration of cyanoacrylate into the lung parenchyma was evidenced by immunofluorescence microscopy. Histologically, when the pleura was resected without using cyanoacrylate, a thick fibrocellular layer extended to the lung parenchyma. Furthermore, severe fibrosis was observed when electrocautery was used for hemostasis. However, when the pleura was resected using cyanoacrylate, the normal alveolar structure was preserved.

CONCLUSIONS

Our uniform pleural defect model using cyanoacrylate may be feasible for the evaluation of synthetic sealants for alveolar air leakage.

Hemostasis and sealing of air leaks in the lung using high-intensity focused ultrasound

BACKGROUND

Operative management of parenchymal lung injury can be complicated by persistent hemorrhage and air leak, which might require resection. Techniques that preserve parenchyma are associated with improved survival. High-intensity focused ultrasound (HIFU) has been demonstrated as a useful method for hemostasis in experimental solid organ injuries. We wished to investigate whether this could be applied to lung injuries.

METHODS

An intraoperative HIFU device (frequency of 5.7 MHz, acoustic power of 65 W), equipped with a titanium coupler, was used. Incisions (average length of 2.5 cm, and depth of 5 mm) were made in the lungs of 11 pigs, which created both parenchymal hemorrhage and air leakage. In treatment experiments, 70 incisions were sealed with HIFU. The HIFU application started within 10 seconds of inducing the injury. Hemostasis was assessed by visual observation of sealed incisions. The possible air leakage was determined by submersing the sealed incision under the layer of water and observing for air bubble formation. In control experiments, five incisions were left untreated to monitor air leaks and bleeding for 2 minutes.

RESULTS

Hemostasis and pneumostasis (sealing of air leaks) of the treated incisions were achieved in 51 +/- 37 seconds (mean +/- SD) (range of 10-210 seconds) of HIFU application time. Over 95% of incisions were hemostatic within 2 minutes of HIFU application. The treatment time was not dependent on the incision length or depth. In control experiments, the air leaking and bleeding were still present at 2 minutes after the injury.

CONCLUSION

Intraoperative HIFU might provide an effective method of hemostasis and control of air leaks from lacerations caused by trauma.

Intrapleural topical application of cisplatin with the surgical carrier Vivostat increases the local drug concentration in an immune-competent rat model with malignant pleuromesothelioma

OBJECTIVE

We sought to investigate whether intrapleural topical application of cisplatin with a surgical carrier has a prolonged local tissue level in comparison with cisplatin solution while reducing systemic toxicity.

METHODS

Forty immune-competent Fischer rats were inoculated with 10(6) mesothelioma cells. Ten days later, left pneumonectomy with tumor debulking was performed. Twenty animals underwent local application of cisplatin solution (100 mg/m2), whereas the same quantity of cisplatin was topically applied as a gel with the Vivostat (Vivolution) system in 20 other animals. In each group 5 subgroups of 4 animals were defined according to the harvesting time of blood and tissue samples (2, 4, 24, and 72 hours and 1 week) after local therapy. Platinum concentrations in serum and tissue and systemic toxicity were analyzed.

RESULTS

Platinum concentrations in tissue were significantly higher in the gel group (group 1) than in the solution group (group 2) at 1, 3, and 7 days after therapy (1510, 1224, and 1069 pg/mg for group 1 vs 598, 382, and 287 pg/mg for group 2; P = .007, P = .005, and P = .0002, respectively). Laboratory findings showed renal insufficiency in the animals of the solution group at 1 week, with values of 98 mmol/L versus 7.7 mmol/L for urea and 410 mumol/L versus 43 mumol/L for creatinine (P = .02 and P = .01, respectively), which was confirmed by means of pathologic analysis.

CONCLUSIONS

Intrapleural administration of cisplatin with the carrier Vivostat significantly provides sustained higher platinum concentrations up to 1 week in tissue in comparison with application of cisplatin solution without conferring systemic toxicity in this model.

Fibrin glue in pulmonary resection: a prospective, randomized, blinded study

BACKGROUND

In contrast to the rare large-airway bronchopleural fistulas after lung resection, peripheral or alveolar air leaks (AAL) are very common, often prolong hospital stay, increase utilization of resources, and on occasion result in significant morbidity. Various adjuncts have been used in attempts to reduce AAL. One of these, the topical application of fibrin glue, has to date failed to demonstrate efficacy in small clinical trials. This study reexamines the role of fibrin glue in routine lobar and wedge pulmonary resections.

METHODS

Of 113 patients enrolled, 13 became ineligible because of intraoperative findings. The remaining 100 patients were randomly assigned to one of two groups at the conclusion of lung resection, regardless of the presence or absence of identifiable air leak. The control group received no additional intervention. The experimental group underwent application of 5 mL of fibrin glue delivered by a pressurized, aerosolized spraying mechanism. Postoperatively a blinded clinical observer recorded outcomes including the incidence and duration of AAL, prolonged AAL (PAAL), the volume of pleural drainage, the time to tube removal, and the postoperative length of stay (LOS), as well as any complications related to treatment.

RESULTS

Both groups were comparable with regard to demographics, diagnoses, and procedures. Statistically significant reductions were found in the experimental group in the overall incidence of AAL (34% versus 68%, p = 0.001), mean duration of AAL (1.1 versus 3.1 days, p = 0.005), mean time to chest tube removal (3.5 versus 5.0 days, p = 0.02), and the incidence of PAAL (2% versus 16%, p = 0.015). There was no significant difference in the volume of chest tube drainage or LOS (4.6 days glue and 4.9 days control, p = 0.318). There were no complications related to the use of fibrin glue.

CONCLUSIONS

Aerosolized fibrin glue appears to be safe and effective in reducing AAL. The overall incidence of AAL was reduced by 50% and PAAL occurred in only 1 treated patient (2% versus the usually reported 15%). Further studies with this and other methods are required to delineate routine versus selective use, to compare methods, and clarify cost benefit.

Intraoperative techniques to prevent air leaks

Persistent air leaks prolong chest tube duration and hospital stay after lung surgery. Air leaks also may lead to life-threatening empyemas. Preventing postoperative air leaks and BPFs is the best treatment for air-leak complications. Meticulous closure of parenchymal, pleural, and bronchial defects is the mainstay of air-leak control. The reinforcement of parenchymal suture and staple lines, pleural apposition, and well-vascularized tissue-flap coverage of bronchial suture and staple lines further reduce the incidence of prolonged air leaks and BPFs.

Physical characteristics of Vivostat patient-derived sealant. Implications for clinical use

This study compared the physical characteristics of Vivostat patient-derived sealant with two conventional fibrin sealants, Tissucol and Beriplast. Vivostat sealant exhibited greater elasticity without compromising tensile strength. Vivostat sealant polymerised at low temperatures (4 and 25 degrees C) or at high temperature (70 degrees C) exhibited similar viscoelastic properties as when polymerised at normal physiological temperature (37 degrees C). Vivostat fibrin I solution can be stored at room temperature for up to 8 h without affecting the mechanical properties of the derived sealant. These physical characteristics of Vivostat patient-derived sealant suggest that it may have suitable stability and performance characteristics for use in a wide range of surgical procedures.