Experimental and histological evaluation of different clamp technique for pulmonary artery

OBJECTIVES

The double-loop technique has been used in our clinical settings for pulmonary arterioplasty and/or injured artery repair during thoracoscopic anatomical lung resection. We evaluated the pressure resistance capacity and intimal load to determine the effectiveness and safety of the double-loop technique.

METHODS

The double-loop technique, DeBakey clamp, Fogarty clamp, endovascular clips and vessel loop technique were evaluated. During an experimental study, a polyvinyl alcohol main pulmonary artery model, manometer and in-deflation device were used to measure the burst pressure. The maximum clamp pressure was measured using a pressure-measuring film. Each measurement was performed 10 times. During the histological study, we measured the burst pressure and evaluated the intimal damage of the human pulmonary artery associated with the double-loop technique and DeBakey clamp.

RESULTS

The experimental burst pressure (mmHg) and maximum clamp pressure (MPa) between the double-loop technique and DeBakey at the third notch were not significantly different (24.6 ± 2.8 and 21.8 ± 2.8, P = 0.094; 1.54 ± 0.12 and 1.49 ± 0.12, P = 0.954). During the histological study, the burst pressures of the double-loop technique and DeBakey at the third notch were also not significantly different (P = 0.754). Furthermore, the double-loop technique resulted in only intimal deformation in each five samples.

CONCLUSIONS

The double-loop technique is feasible for thoracoscopic anatomical lung resection because it has similar pressure resistance capacity and intimal load as DeBakey at the 3rd notch.

Impact of lock solutions on the mechanical performance of polyurethane central venous catheters: A comparative study

The impact of ethanol locks on the mechanical performances of central venous catheters was compared to that of aqueous-based locks. Several mechanical tests were performed to evaluate catheter behavior: kinking radius measurements, burst pressure, and tensile tests. Different polyurethanes were studied to assess the impact of radio-opaque charge and polymer chemical composition on catheter behavior. The results were correlated to swelling measurements and calorimetric measurements. In particular, ethanol locks have a higher impact on long contact time than aqueous-based locks: stresses and strains at break were lower, and kinking radii were higher. However, for all catheters, the mechanical performances remain much higher than the normative requirements.

A vertical additive-lathe printing system for the fabrication of tubular constructs using gelatin methacryloyl hydrogel

Reproducing both the mechanical and biological performance of native blood vessels remains an ongoing challenge in vascular tissue engineering. Additive-lathe printing offers an attractive method of fabricating long tubular constructs as a potential vascular graft for the treatment of cardiovascular diseases. Printing hydrogels onto rotating horizontal mandrels often leads to sagging, resulting in poor and variable mechanical properties. In this study, an additive-lathe printing system with a vertical mandrel to fabricate tubular constructs is presented. Various concentrations of gelatin methacryloyl (gelMA) hydrogel were used to print grafts on the rotating mandrel in a helical pattern. The printing parameters were selected to achieve the bonding of consecutive gelMA filaments to improve the quality of the printed graft. The hydrogel filaments were fused properly under the action of gravity on the vertical mandrel. Thus, the vertical additive-lathe printing system was used to print uniform wall thickness grafts, eliminating the hydrogel sagging problem. Tensile testing performed in both circumferential and longitudinal direction revealed that the anisotropic properties of printed gelMA constructs were similar to those observed in the native blood vessels. In addition, no leakage was detected through the walls of the gelMA grafts during burst pressure measurement. Therefore, the current printing setup could be utilized to print vascular grafts for the treatment of cardiovascular diseases.

Is staple line reinforcement still needed on contemporary staplers? A benchtop analysis

BACKGROUND

Staple line reinforcement (SLR) is commonly used in bariatric surgeries to reduce leaks and bleeds. With the evolution of staplers, the need for buttressing with the latest surgical stapling technology is in question. The efficacy of GORE® SEAMGUARD® (G-SLR) to improve staple line strength based on an established measure of burst pressure was evaluated. A benchtop test on synthetic tissue evaluated the pressure required for staple line leak across surgical staplers with and without G-SLR.

METHODS

Staple lines on a consistent thickness synthetic bowel were pressurized to the point of failure (burst pressure) among Ethicon®, Intuitive®, and Medtronic® surgical staplers with and without G-SLR. Burst pressure and leak location (through the staple line [TTSL] or through the staple [TTS], on the anvil or cartridge side) were recorded. Visual confirmation of a leak concluded each test.

RESULTS

The pooled mean burst pressure for G-SLR was greater (p < 0.05) by 0.494 pounds/square inch compared with no reinforcement with no meaningful differences among staplers. Leak failures were primarily TTS (91.7%) and equally distributed between reinforcement groups with more leak failures on the cartridge side with G-SLR and on the anvil side for non-SLR group. Leaks occurred across the length of staple lines with no discernable pattern.

CONCLUSION

Employing a buttressing material strengthens the staple line, as measured by burst pressure, and may reduce the risk for staple line failure. This benchtop study of G-SLR with three commonly used surgical staplers demonstrated a significant increase in burst pressures among the studied stapling devices.

The mechanical characterization of blood vessels and their substitutes in the continuous quest for physiological-relevant performances. A critical review

During the last 50 years, novel biomaterials and tissue engineering techniques have been investigated to produce alternative vascular substitutes that recapitulate the unique elastic mechanical features of blood vessels. A large variation in mechanical characterization, including the test type, protocol, and data analysis, is present in literature which complicates the comparison among studies and prevents the blooming and the advancement of this field. In addition, a limited mechanical assessment of the substitute for the intended application is often provided. In this light, this review presents the mechanical environment of blood vessels, discusses their mechanical behavior responsible for the suited blood flow into the body (non-linearity, anisotropy, hysteresis, and compliance), and compares the mechanical properties reported in literature (obtained with compression, tensile, stress-relaxation, creep, dynamic mechanical analysis, burst pressure, and dynamic compliance tests). This perspective highlights that the mechanical properties extracted through conventional tests are not always suitable indicators of the mechanical performance during the working life of a vascular substitute. The available tests can be then strategically used at different stages of the substitute development, prioritizing the simplicity of the method at early stages, and the physiological pertinence at later stages, following as much as possible ISO standards in the field. A consistent mechanical characterization focused on the behavior to which they will be subdued during real life is one key and missing element in the quest for physiological-like mechanical performance of vascular substitutes.

Stapler-less burst pressure in an ex vivo human gastric tissue: a randomized controlled trial

Stapler-less laparoscopic sleeve gastrectomy (LSG) is emerging as a new potential affordable cost-effective alternative procedure. However, no pre-clinical data are currently available on human tissue. We aimed to evaluate whether traditionally suturing without the use of surgical stapling may produce a comparable bursting pressure on human gastric tissue. A prospective cohort of consecutive patients undergoing LSG was divided in two groups to compare a barbed extra-mucosal running suture (stapler-less) versus a standard stapler line. A burst pressure test was applied to the gastric specimen employing high-resolution manometric catheter. Type, location and features of the leak were described. We enrolled a total of 40 obese patients, 20 patients for each group. Median burst pressures of the stapler-less group resulted statistically significant increased (p < 0.0001) than the one in standard stapler group. In all cases, leak occurred along the surgical closure site independently from the used technique (group 1 vs 2; p = N.S.), more often at the proximal stomach (p < 0.05). In human ex vivo model, traditional surgical suture (i.e. running hand-sewn) produced an effective temporary closure, with superior resistance to increasing volume and pressure. How this may impact on clinical LSG outcomes needs further evaluations and was not the object of this study.

Safety and effectiveness of a novel generator algorithm for bipolar vessel sealing: a randomised controlled chronic animal study

BACKGROUND

Electrosurgical vessel sealers are gradually replacing conventional techniques such as ligation and clipping. Algorithms that control electrosurgical units (ESU), known as modes, are important for applications in different surgical disciplines. This chronic porcine animal study aimed to evaluate the safety and effectiveness of the novel thermoSEAL electrosurgical vessel sealing mode (TSM). The BiClamp® mode (BCM) of the renowned VIO® 300 D ESU served as control. BCM has been widely available since 2002 and has since been successfully used in many surgical disciplines. The TSM, for the novel VIO® 3 ESU, was developed to reduce sealing time and/or thermal lateral spread adjacent to the seal while maintaining clinical success rates. The primary aim of this study was to investigate the long-term and intraoperative seal quality of TSM.

METHODS

The BiCision® device was used for vessel sealing with TSM and BCM in ten German Landrace pigs which underwent splenectomy and unilateral nephrectomy during the first intervention of the study. The seals were cut with the BiCision® knife. Ninety-nine arteries, veins and vascular bundles were chronically sealed for 5 or 21 days. Thereafter, during the second and terminal intervention of the study, 97 additional arteries and veins were sealed. The carotid arteries were used for histological evaluation of thermal spread.

RESULTS

After each survival period, no long-term complications occurred with either mode. The intraoperative seal failure rates, i.e. vessel leaking or residual blood flow after the first sealing activation, were 2% with TSM versus 6% with BCM (p = 0.28). The sealing time was significantly shorter with TSM (3.5 ± 0.69 s vs. 7.3 ± 1.3 s, p < 0.0001). The thermal spread and burst pressure of arteries sealed with both modes were similar (p = 0.18 and p = 0.61) and corresponded to the histological evaluation. The measured tissue sticking parameter was rare with both modes (p = 0.33). Tissue charring did not occur. Regarding the cut quality, 97% of the seals were severed in the first and 3% in the second attempt (both with TSM and BCM).

CONCLUSIONS

The novel TSM seals blood vessels twice as fast as the BCM while maintaining excellent tissue effect and clinical success rates.

TRIAL REGISTRATION

Not applicable.

Effects of corrosion defect and tensile load on injection pipe burst in CO2 flooding

Highly pressurized injection pipelines in CO₂ flooding often suffer from different types of corrosion defects and mechanical stresses and can easily cause serious damage to the environment. Currently, the descending rule of pipe burst pressures under different defect parameters and tensile loads has not been studied systematically. In this study, a section of injection pipe was used to simulate the burst process of pipe with groove and general corrosion defects. The crack appearance showed that the fracture began at the centre of the longitudinal defect line as an instantaneous ductile rupture and then extended along both sides as a rapid brittle rupture under high stress. The burst pressure in the groove corrosion defect tests showed that the defect depth played a more dominant role in pipe burst than the defect length did, and when a 30 MPa axial tensile load was added, the pipe burst pressure was reduced approximately 20-30%. In general corrosion defect tests, the burst pressures were generally much lower than the groove corrosion defect tests produced, and when adding the axial tensile load, the burst mode changed. Moreover, the value of the burst pressure can be a sign of BLEVE (boiling liquid expanding vapor explosion) severity.

Towards compliant small-diameter vascular grafts: Predictive analytical model and experiments

The search for novel, more compliant vascular grafts for the replacement of blood vessels is ongoing, and predictive tools are needed to identify the most promising biomaterials. A simple analytical model was designed that enables the calculation of the ratio between the ultimate stress (σ_ult) and the elastic modulus (E). To reach both the compliance of small-diameter coronary arteries (0.0725%/mmHg) and a burst pressure of 2031 mmHg, a material with a minimum σ_ult/E ratio of 1.78 is required. Based on this result and on data from the literature, random electrospun Polyurethane/Polycaprolactone (PU/PCL) tubular scaffolds were fabricated and compared to commercial ePTFE prostheses. PU/PCL grafts showed mechanical properties close to those of native arteries, with a circumferential elastic modulus of 4.8 MPa and a compliance of 0.036%/mmHg at physiological pressure range (80-120 mmHg) for a 145 μm-thick prosthesis. In contrast, commercial expanded polytetrafluoroethylene (ePTFE) grafts presented a high Young's modulus (17.4 MPa) and poor compliance of 0.0034%/mmHg. The electrospun PU/PCL did not however reach the target values as its σ_ult/E ratio was lower than expected, at 1.54, well below the calculated threshold (1.78). The model tended to overestimate both the compliance and burst pressure, with the differences between the analytical and experimental results ranging between 13 and 34%, depending on the pressure range tested. This can be explained by the anisotropy of random electrospun PU/PCL and its slightly non-linear elastic behavior, in contrast to the hypotheses of our model. Impermeability tests showed that the electrospun scaffolds were impermeable to blood for all thicknesses above 50 μm. In conclusion, this analytical model allows to select materials with suitable mechanical properties for the design of small-diameter vascular grafts. The novel electrospun PU/PCL tubular scaffolds showed strongly improved compliance as compared to commercial ePTFE prostheses.

Roux-en-Y Gastric Bypass: Does the Direction of Staples Matter?

PURPOSE

Mechanical gastro-intestinal anastomosis using stapler is a critical step in laparoscopic Roux-en-Y gastric bypass (RYGB). To date the effect of the direction of staples on anastomotic leak has not been investigated. The study aim was to investigate the impact of the direction of staples on the integrity of the gastro-jejunal anastomosis.

MATERIALS AND METHODS

Eight gastro-jejunostomy (GJ) models were performed using porcine stomach and small intestine. Specimens were divided into group A where the cartridge was in the gastric lumen with the anvil in the jejunal lumen and vice versa in group B. Enterotomy was closed and gastric and jejunal ends were stapled off. Burst pressure (BP) was measured by infusion of methylene blue saline into the GJ model until leak occurred. Site of leak, BP, and total volume (TV) infused were recorded. Compliance (C) was calculated from the equation ΔTV/ΔBP.

RESULTS

The BP was greater in group A compared to group B (18 mmHg (range 15-25) versus 11 mmHg (range 8-15); p = 0.045) despite similar TV between the groups 60.00 mL (range 55.00-65.00) versus 51.25 mL (range 40.00-60.00); p = 0.11). The compliance did not significantly differ between groups A and B (6.38 mL/mmHg (range 4.34-8.59) versus 5.61 mL/mmHg (range 3.93-7.21); p = 0.48).

CONCLUSION

BP recorded when the stapler cartridge was introduced in the gastric lumen was higher than when it was introduced from the jejunal lumen. The lack of difference in compliance between groups suggests that the difference in BP was due to the difference in the direction of staples.

Mechanical properties and failure analysis of visible light crosslinked alginate-based tissue sealants

Moderate to weak mechanical properties limit the use of naturally-derived tissue sealants for dynamic medical applications, e.g., sealing a lung leak. To overcome these limitations, we developed visible-light crosslinked alginate-based hydrogels, as either non-adhesive methacrylated alginate (Alg-MA) hydrogel controls, or oxidized Alg-MA (Alg-MA-Ox) tissue adhesive tissue sealants, which form covalent bonds with extracellular matrix (ECM) proteins. Our study investigated the potential for visible-light crosslinked Alg-MA-Ox hydrogels to serve as effective surgical tissue sealants for dynamic in vivo systems. The Alg-MA-Ox hydrogels were designed to be an injectable system, curable in situ. Burst pressure experiments were conducted on a custom-fabricated burst pressure device using constant air flow; burst pressure properties and adhesion characteristics correlated with the degrees of methacrylation and oxidation. In summary, visible light crosslinked Alg-MA-Ox hydrogel tissue sealants form effective seals over critically-sized defects, and maintain pressures up to 50mm Hg.

Evaluation of the LigaSure(™) Vessel Sealing System for bowel transection and intestinal anastomosis-an experimental study in a porcine model

BACKGROUND

The purpose of the present study is to assess the value of the LigaSure™ Vessel Sealing System (LVSS) as a means for bowel transection and intestinal anastomosis.

METHODS

We compared the LVSS for (1) transecting bowel and (2) creation of an intestinal anastomosis with standard methods such as stapler (S) and hand-sewn (HS) in a porcine model. For each study arm, i.e., bowel transection and anastomosis creation, both the small bowel and colon were examined. In total, ten transections and ten anastomoses were performed for each. Burst and anastomotic leak pressures were compared.

RESULTS

In the study arm 1, LVSS achieved lowest burst pressures in both small bowel (LVSS 39.8 ± 3.6 mmHg, S 81.9 ± 3.9, HS 111.9 ± 14.7 mmHg, p < 0.0001) and colon transections (LVSS 21.5 ± 2.6 mmHg, S 79.5 ± 4.9, HS 91.0 ± 5.2 mmHg, p < 0.0001). There was no difference in burst pressures between S and HS in both small bowel and colon transections. In the study arm 2, LVSS showed the lowest anastomotic leak pressures for small bowel (LVSS 26.4 ± 2.6 mmHg, S 52.1 ± 6.2, HS 87.4 ± 7.0 mmHg, p < 0.0001) and colonic anastomoses (LVSS 16.9 ± 1.3 mmHg, S 55.9 ± 4.3, HS 74.4 ± 4.4 mmHg, p < 0.0001). Furthermore, small bowel and colonic anastomoses using S demonstrated significantly lower leak pressures than HS anastomosis p < 0.001 and p = 0.004, respectively.

CONCLUSIONS

The LVSS achieves significantly lower burst pressures and anastomotic leak pressures for bowel transection and intestinal anastomosis than S and HS techniques. However, due to the achieved pressure levels of 39.8 ± 3.6 mmHg, LVSS appears to be a sufficient stand-alone method for bowel transection. Whether it can be used to perform intestinal anastomosis warrants further research in a survival model.

Comparison of Reinforcement Techniques Using Suture on Staple-Line in Sleeve Gastrectomy

BACKGROUND

Sleeve gastrectomy is a common procedure in recent years for treatment of morbid obesity however leak from staple-line is its main challenging complication. Despite numerous studies regarding leak after sleeve gastrectomy, there is still no conclusion on reinforcement of staple-line in this procedure. The purpose of this study was to compare two methods of oversewing staple-line versus no reinforcement.

METHODS

Resected stomachs of 30 patients undergoing laparoscopic sleeve gastrectomy were evaluated for bursting pressure immediately after extraction from the abdomen. Reinforcement technique was applied in random order to 3 segments of the staple-line on each specimen: continuous Lembert's sutures, continuous through-and-through sutures, and no reinforcement. Bursting pressure was determined by injection of methylene blue solution into lumen of resected stomach and recording pressure at which leakage occurs. Location of leak, intragastric pressure, and volume at first leak were recorded.

RESULTS

Baseline characteristics of patients were similar in randomized groups for order of reinforcement technique. Mean ischemia time of specimens was 17.4 ± 10.4 min. No leaks were observed in segments reinforced with Lembert's oversewing technique. The through-and-through reinforcement segments were first to leak in 21 out of 30 cases (70 %) with mean leak pressure of 570 mmHg and mean leak volume of 399 ml. Leakage occurred in 9 segments (30 %) with no reinforcement with a leak pressure of 329 mmHg and volume of 380 ml.

CONCLUSIONS

In vitro, Lembert's suture reinforcement technique on stapled human stomach is associated with less leakage rate in comparison to through-and-through reinforcement and non-reinforced staple-line.

Vessel sealing comparison: old school is still hip

BACKGROUND

Ligation with either absorbable or non-absorbable sutures has been the traditional state of the art, but a proliferation of technology now offers a host of methods to close and divide vessels. Only limited data are available that objectively compare different vessel sealing methods. The objective of this study was to compare a broad variety of methods of surgical vessel closure in a reproducible, independent, standardized test-to-failure ex vivo pressure challenge.

METHODS

Ten of the most common surgical sealing devices were represented in this study, including both mechanical and energy devices. Unfixed porcine carotid arteries were selected for testing. They were connected to a pump, and automated controlled infusion was initiated. Upon identification of a leak at the source of sealing, the maximum pressure in mmHg was logged.

RESULTS

There were a total of 184 trials conducted using the 10 vessel sealing methods. The average burst pressure across all trials was 1100 mmHg with a range of 51.3-5171 mmHg. Suture-based methods displayed the highest average pressure until failure. Stapling methods showed the lowest burst pressures. All methods showed mean burst pressures above the "physiologically relevant" level of 250 mmHg.

CONCLUSIONS

This study presents an independent, reproducible, ex vivo comparison of multiple methods of surgical arterial closure. In these laboratory conditions, tests to failure demonstrated widely varying sealing strength, highly dependent on method. All hemostatic modalities tested are capable of securing vessels safely and well above physiologic blood pressures, while suture-based methods were significantly stronger than other mechanical methods or modern energy devices.

Staple Line Reinforcement Methods in Laparoscopic Sleeve Gastrectomy: Comparison of Burst Pressures and Leaks

Background and Objectives:

Laparoscopic sleeve gastrectomy is a technically simple and popular bariatric operation with acceptable results. However, leaks can occur in long staple lines, for which various reinforcement methods are used. We compared nonreinforced stapling in laparoscopic sleeve gastrectomy with 3 staple line reinforcement methods: suturing, absorbable buttressing material, and fibrin glue.

Methods:

From March 1 until September 30, 2014, 118 patients with body mass index >40 kg/m² underwent sleeve gastrectomy and were enrolled in 4 groups, depending on the type of reinforcement used. The resected stomach specimens were treated with the same methods of reinforcement as used in the surgeries in the corresponding patients and then insufflated until a burst occurred. The burst pressures of the resected stomach specimens and adverse postoperative events were recorded.

Results:

Five postoperative leaks occurred in the reinforcement groups (fibrin glue, 2; absorbable buttresses, 2; sutures, 1); no leaks were evident in the no-reinforcement group. Suturing afforded the highest burst pressure and took the longest to perform of the methods. There was no correlation between the leaks and burst pressures. All of the leaks occurred in the proximal fundus in the resected stomach specimens and in the affected patients.

Discussion:

Although most surgeons use additional reinforcement on long staple lines in sleeve gastrectomy, there is no consensus about its necessity. We did not show any benefit of such reinforcement methods over proper stapling technique alone.

Conclusion:

Laparoscopic sleeve gastrectomy without staple line reinforcement is safe and avoids additional costs for reinforcement materials.

Use of bioabsorbable staple reinforcement material in side-to-side anastomoses: Suture line reinforcement of the weak point of the anastomosis

BACKGROUND

Few studies have been designed regarding optimal reinforcement of the crotch of a side-to-side anastomosis. The purpose of this study was to clarify the weak point of the side-to-side anastomosis and to evaluate the effect of bioabsorbable reinforcement material.

METHODS

Fresh pig small bowel was used for all experiments. A side-to-side anastomosis was performed using a linear stapler, and the burst pressure of the anastomosis was measured. Three separate experiments were done. In experiment 1, the weak point and the burst pressure of that point were defined. In experiment 2, the burst pressure of the side of the anastomosis was measured. In experiment 3, we evaluated the effect of Neoveil(®) to strengthen the weak point of the anastomosis.

RESULTS

The weak point of the side-to side anastomosis was the crotch and the burst pressure was 39.8 ± 5.7 mmHg. The burst pressure of the side of the anastomosis was 109.9 ± 7.9 mmHg. This was significantly higher than the burst pressure of the crotch (P = 0.008). The burst pressure of the crotch in the group with Neoveil(®) was 83.3 ± 14.9 mmHg. This pressure was significantly higher than the group with no Neoveil(®) reinforcement (P = 0.001).

CONCLUSION

These findings suggest that the use of Neoveil(®) as a buttressing material is associated with reinforced staple lines and increased crotch burst pressures compared to non-buttressed staple lines. Neoveil(®) was found to perform comparably to clinically available buttress materials in this ex vivo model. Reinforcement of the weak point of the side-to-side anastomosis with Neoveil(®)may lead to fewer anastomotic leaks.

Effect of Intensified Decellularization of Equine Carotid Arteries on Scaffold Biomechanics and Cytotoxicity

Decellularized equine carotid arteries (dEAC) are suggested to represent an alternative for alloplastic vascular grafts in haemodialysis patients to achieve vascular access. Recently it was shown that intensified detergent treatment completely removed cellular components from dEAC and thereby significantly reduced matrix immunogenicity. However, detergents may also affect matrix composition and stability and render scaffolds cytotoxic. Therefore, intensively decellularized carotids (int-dEAC) were now evaluated for their biomechanical characteristics (suture retention strength, burst pressure and circumferential compliance at arterial and venous systolic and diastolic pressure), matrix components (collagen and glycosaminoglycan content) and indirect and direct cytotoxicity (WST-8 assay and endothelial cell seeding) and compared with native (n-EAC) and conventionally decellularized carotids (con-dEAC). Both decellularization protocols comparably reduced matrix compliance (venous pressure compliance: 32.2 and 27.4% of n-EAC; p < 0.01 and arterial pressure compliance: 26.8 and 23.7% of n-EAC, p < 0.01) but had no effect on suture retention strength and burst pressure. Matrix characterization revealed unchanged collagen contents but a 39.0% (con-dEAC) and 26.4% (int-dEAC, p < 0.01) reduction of glycosaminoglycans, respectively. Cytotoxicity was not observed in either dEAC matrix which was also displayed by an intact endothelial lining after seeding. Thus, even intensified decellularization generates matrix scaffolds highly suitable for vascular tissue engineering purposes, e.g., the generation of haemodialysis shunts.

Usefulness of vessel-sealing devices for ≤7 mm diameter vessels: a randomized controlled trial for human thoracoscopic lobectomy in primary lung cancer

OBJECTIVES

Vessel-sealing devices (VSDs) are widely used for various surgical procedures, including thoracoscopic surgery, but very few reports have compared their safety and usefulness with human thoracoscopic lobectomy procedures not employing VSDs.

METHODS

Primary lung cancer patients for whom a thoracoscopic lobectomy involving mediastinal lymph node dissection was planned in our department from April 2011 to March 2013 were recruited for the study. Patients were randomly allocated to a control group (n = 14) or a VSD group (n = 44), which comprised three sub-groups, namely EnSeal (n = 17), LigaSure (n = 15) and Harmonic (n = 12). The control group comprised patients undergoing surgery solely with ligation and conventional electrocautery. EnSeal, LigaSure and Harmonic were chosen because they are the three most popular disposable VSDs used in Japan. In the VSD groups, the proximal side of pulmonary artery stumps (≤7 mm diameter) were ligated and then treated with respective devices. Primary end-points were burst pressure of the pulmonary artery stump (measured using resected specimens), operative time, intraoperative blood loss, instances of endostapler use, intraoperative surgeon stress (assessed by visual analogue scale) and postoperative drainage volume and duration. As a secondary objective, the individual VSD groups were also compared with each other.

RESULTS

The burst pressure of ligation-treated pulmonary artery stumps was higher than that of VSD-treated stumps (P <0.0001). The burst pressure of <5-mm-wide VSD-treated stumps was higher than that of ≥5-mm-wide stumps (P = 0.0421). However, the burst pressure for all groups and all vessel diameters was sufficient to withstand the physiological pulmonary artery pressure. The VSD group demonstrated reduced intraoperative blood loss (P = 0.0241), surgeon stress (P = 0.0002), postoperative drainage volume (P = 0.0358) and shortened postoperative drainage duration (P = 0.0449). Operative time and the instances of endostapler use did not significantly differ. Comparison between each of the VSD groups revealed no significant differences. None of the patients experienced serious perioperative complications or died because of surgery.

CONCLUSION

VSD is simple and safe to use in thoracoscopic lobectomy involving mediastinal lymph node dissection for primary lung cancer. Furthermore, none of the VSDs used in this study presented any observable differences in quality that could lead to clinical problems.

Femtosecond-UVA-riboflavin (FUR) cross-linking approach to penetrating keratoplasty and anterior lamellar keratoplasty

PURPOSE

To introduce femtosecond laser wound design combined with riboflavin/ultraviolet light-A (UVA) collagen cross-linking at the wound for penetrating (PKP) and anterior lamellar keratoplasty (ALK). Primary outcomes were intraocular pressure (IOP in mmHg) at burst point for the PKP group, and tensile strength (kPa) until dehiscence for the ALK group.

METHODS

Human corneoscleral rims (N = 20) were mounted on artificial anterior chambers. PKP specimens underwent FUR, femtosecond laser-cut without cross-linking, or conventional corneal transplantation. PKP maximum burst IOP with progressive suture removal was assessed by a digital manometer, in triplicate and by three observers. ALK involved whole human globes (N = 10) divided into three groups using a 200-micron, 8 mm diameter donor lenticule, with or without cross-linking. Cross-linked specimens were exposed to UVA light (3 mW/cm(2) irradiance, 3.4 J, 370 nm wavelength) for 30 min with 0.1% riboflavin (20% Dextran) applied every 2-min. ALK tensile strength was determined using a digital tensiometer.

RESULTS

In PKP, burst IOP was 31.32 mmHg greater for corneas that underwent the UVA-riboflavin treatment than for those that did not (p < 0.05). There was no significant relationship (p = 0.719) established between cut design (femtosecond versus conventional). On multivariate analysis, there was a mean of 15.82 mmHg higher sustainable pressure for each stabilization suture present (p < 0.0001). In ALK, specimens comprised of human donor and human recipient tissue combined with UVA-riboflavin therapy experienced the greatest level of adhesion strength (954.7 ± 290.4 kPa) as shown by the force required to separate the tissues, and compared to non-cross-linked specimens. Electron microscopy of ALK specimens showed non-fused and fused longitudinal cross-linked collagen fibers as well as bridges, densities, attachment plaques and primitive plasmalemmal densities.

CONCLUSIONS

Cross-linking effects of the FUR technique enable a stronger graft-recipient adhesion compared to conventional penetrating and anterior lamellar keratoplasty. Electron microscopy enabled visualization of cross-linked interface and potential bonding. The FUR approach may further lead to sutureless transplantation techniques in the future.

SETTING/VENUE

ImagePlus Laser Eye Centre, Winnipeg, and University of Ottawa Eye Institute, Ottawa, Canada.