Exploring new technologies to facilitate laparoscopic surgery: creating intestinal anastomoses without sutures or staples, using a radio-frequency-energy-driven bipolar fusion device

Development of implantable electrode based on bioresorbable Mg alloy for tissue welding application

An implantable electrode based on bioresorbable Mg-Nd-Zn-Zr alloy was developed for next-generation radiofrequency (RF) tissue welding application, aiming to reduce thermal damage and enhance anastomotic strength. The Mg alloy electrode was designed with different structural features of cylindrical surface (CS) and continuous long ring (LR) in the welding area, and the electrothermal simulations were studied by finite element analysis (FEA). Meanwhile, the temperature variation during tissue welding was monitored and the anastomotic strength of welded tissue was assessed by measuring the avulsion force and burst pressure. FEA results showed that the mean temperature in the welding area and the proportion of necrotic tissue were significantly reduced when applying an alternating current of 110 V for 10 s to the LR electrode. In the experiment of tissue welding ex vivo, the maximum and mean temperatures of tissues welded by the LR electrode were also significantly reduced and the anastomotic strength of welded tissue could be obviously improved. Overall, an ideal welding temperature and anastomotic strength which meet the clinical requirement can be obtained after applying the LR electrode, suggesting that Mg-Nd-Zn-Zr alloy with optimal structure design shows great potential to develop implantable electrode for next-generation RF tissue welding application.

A novel electrode for reducing tissue thermal damage in radiofrequency-induced intestinal anastomosis

PURPOSE

This study aimed to design a novel electrode for reducing tissue thermal damage in radiofrequency-induced intestinal anastomosis.

MATERIAL AND METHODS

We developed and compared two electrodes (Ring electrode, and Plum electrode with reduced section of the middle fusion area by nearly 80% arising from novel structural design) by performing ex-vivo experiments and finite element analysis.

RESULTS

In contrast to the Ring electrode group, slightly higher mean strength is acquired with the tensile force and burst pressure results increasing from 9.7 ± 1.47 N, 84.0 ± 5.99 mmHg to 11.1 ± 1.71 N, 89.4 ± 6.60 mmHg, respectively, as well as a significant reduction in tissue thermal damage for the Plum electrode group, with compression pressure of 20 kPa, RF energy of 120 W and welding duration of 8 s applied to the target regions to achieve anastomosis. Besides, the novel structural design of the Plum electrode can counteract the tension generated by intestinal peristalsis and enhance the biomechanical strength of the anastomotic area. The histological observation showed that the fusion area of the two-layer intestinal tissue is tightly connected with decreased thickness.

CONCLUSION

The novel electrode (Plum electrode) could reduce tissue thermal damage in radiofrequency-induced intestinal anastomosis.

An ex vivo preliminary investigation into the impact of parameters on tissue welding strength in small intestine mucosa-mucosa end-to-end anastomosis

Background: Tissue welding is an electrosurgical technique that can fuse tissue for small intestine anastomosis. However, limited knowledge exists on its application in mucosa-mucosa end-to-end anastomosis. This study investigates the effects of initial compression pressure, out-put power, and duration time on anastomosis strength ex vivo in mucosa-mucosa end-to-end anastomosis. Methods: Ex vivo porcine bowel segments were used to create 140 mucosa-mucosa end-to-end fusions. Different experimental parameters were employed for fusion, including initial com-pression pressure (50kPa-400 kPa), output power (90W, 110W, and 140W), and fusion time (5, 10, 15, 20 s). The fusion quality was measured by burst pressure and optical microscopes. Results: The best fusion quality was achieved with an initial compressive pressure between 200 and 250 kPa, an output power of 140W, and a fusion time of 15 s. However, an increase in output power and duration time resulted in a wider range of thermal damage. There was no significant difference between the burst pressure at 15 and 20 s (p > 0.05). However, a substantial increase in thermal damage was observed with longer fusion times of 15 and 20 s (p < 0.05). Conclusion: The best fusion quality for mucosa-mucosa end-to-end anastomosis ex vivo is achieved when the initial compressive pressure is between 200 and 250 kPa, the output power is approximately 140W, and the fusion time is approximately 15 s. These findings can serve as a valuable theoretical foundation and technical guidance for conducting animal experiments in vivo and subsequent tissue regeneration.

Ex vivo evaluation of a technique for equine jejunocecal anastomosis using radiofrequency thermofusion and a Cushing oversew

OBJECTIVE

To describe a technique for a side-to-side jejunocecal anastomosis in horses using radiofrequency thermofusion (TF) of the intestines supported by a Cushing oversew and to compare this anastomosis to handsewn and stapled techniques.

STUDY DESIGN

Ex vivo study.

SAMPLE POPULATION

Intestinal tracts from 24 slaughtered horses.

METHODS

A radiofrequency device was used to perform a jejunocecal anastomosis (Group RFA). The construction time and bursting pressure of this construct were compared with those of a hand-sewn double layer (Group HS) and stapled anastomoses (Group ST) without oversew of the staple line. Histology was also performed for the TF anastomoses to evaluate the extent of the thermal damage.

RESULTS

The median (range) construction time (min) for the TF (15.8 [14.4-16.8]) was not significantly different from that for the HS (25.5 [24.2-26.3]) and ST (10.8 [9.7-12.5]) groups (p = .07). The construction time for ST was shorter than that for HS group (p < .001). The average (standard deviation) bursting pressure (mmHg) for HS (153.1 +/- 17.5) was higher than that for RFA (76 +/- 15) and ST groups (48 +/- 13; p < .001). The bursting pressure of the RFA was higher than that of the ST anastomoses (p = .001). The thermal damage caused by the device was within the suture oversew in the deeper layers, whereas it extended a few mm beyond the suture line in the serosa.

CONCLUSION

Radiofrequency assisted anastomoses provide similar construction times to current techniques and have a higher bursting pressure than ST anastomoses.

CLINICAL SIGNIFICANCE

Radiofrequency-assisted anastomoses with a suture oversew demonstrated comparable bursting pressures to ST anastomoses. The use of the radiofrequency device on the intestine is extra label and causes serosal tissue damage, which may increase the risk of adhesions.

Ex-Vivo Evaluation of "First Tip Closing" Radiofrequency Vessel Sealing Devices for Swine Small Intestinal Transection

This study compared burst pressure (BP), number of activations, and histological assessment of ex vivo swine small intestine loops transected by stapler, a single fulcrum radiofrequency vessel sealing (RFVS) device, and the newly-developed jaws RFVS. Fifty (n = 50) 20 cm long jejunal loops were randomly assigned to be transected with RFVS devices and linear stapler (Caiman5, Caiman Maryland, Caiman12, Ligasure Atlas, and Stapler group as control respectively). Caiman5, Caiman12 and stapler required only one activation to complete the sealing. The mean BP in Caiman5 and Caiman Maryland groups were significantly lower (p < 0.05) than the S group as control and the other RFVS devices studied. RFVS Caiman12 and Ligasure Atlas produced mean BP values that were close to the Control and did not differ between them. The lumen was totally closed in the Caiman12 and Ligasure Atlas groups. The findings of this investigation were promising; we discovered that Caiman12 and Ligasure Atlas produce comparable mechanical capabilities as well as stapled intestinal closure, however Caiman12 need a single activation to complete the transection.

Comparison of the Electrothermal Bipolar Sealing System (LigaSure) Versus Endoloop in Pediatric Laparoscopic Appendectomy

Background: Laparoscopic appendectomy has long been in the process of replacing open appendectomy owing to a better wound healing, better cosmetic appearance, less pain, and less postoperative adhesion. Although there are many methods for ligating the appendix stump, studies on energy-based coagulation methods have attracted great interest in recent years. In our study, we aimed to compare the use of LigaSure™ appendiceal sealing and ligation of appendiceal stump by endoloop with regard to duration of surgery, length of hospital stay, and complications in laparoscopic appendectomies. Materials and Methods: A total of 174 consecutive patients under the age of 18 who underwent laparoscopic appendectomy in our clinic between September 2016 and February 2021 were retrospectively analyzed. Patients with perforated appendicitis were excluded from the study. The patients were divided into two groups as the appendix stump was ligated with endoloop (Group 1) and sealed with LigaSure (Group 2). Demographic characteristics of the patients, duration of surgery, length of hospital stay, and complications were recorded. Results: Of the 132 patients who were included in the study, Group 1 consisted of patients using endoloop (n = 39) and Group 2 comprised patients that LigaSure was employed (n = 93). There was no significant difference between Groups 1 and 2 in terms of age and length of hospital stay (P = .126 and P = .784, respectively); however, the operation time was found to be significantly shorter in Group 2 (P < .001). Conclusion: The use of LigaSure is a safe and fast method to seal the mesoappendix and appendix stump in pediatric laparoscopic appendectomy. We think that infection complications due to stump leakage and intra-abdominal spillage will less be encountered.

Temperature Distribution of Vessel Tissue by High Frequency Electric Welding with Combination Optical Measure and Simulation

In clinical surgery, high frequency electric welding is routinely utilized to seal and fuse soft tissues. This procedure denatures collagen by electrothermal coupling, resulting in the formation of new molecular crosslinks. It is critical to understand the temperature distribution and collagen structure changes during welding in order to prevent thermal damage caused by heat generated during welding. In this study, a method combining optical measurement and simulation was presented to evaluate the temperature distribution of vascular tissue during welding, with a fitting degree larger than 97% between simulation findings and measured data. Integrating temperature distribution data, strength test data, and Raman spectrum data, it is discovered that optimal parameters exist in the welding process that may effectively prevent thermal damage while assuring welding strength.

LigaSure Vessel Sealing System for Small Bowel Transection During Roux Limb Construction

Roux limb construction is an essential part of several major reconstructive hepatobiliary and upper gastrointestinal surgeries. This can be achieved with a stapling device or suturing. For over two decades, the LigaSure vessel sealing systems (Medtronic, MN, USA) have been in use for omental division, mesenteric transection, and sealing of vessels. We used the LigaSure vessel sealing system with a ForceTriad energy platform (Medtronic) for transection of the bowel during the formation of the Roux limb for a Roux-en-Y reconstruction. Between July 2019 and December 2020, patients who had Roux limb construction as part of a pancreato-enteric anastomosis in surgery for chronic pancreatitis were analysed. The data was reviewed from a prospectively maintained database. Fifteen patients had undergone surgery for chronic pancreatitis. The mentioned technique takes approximately eight minutes to construct a Roux limb. There was no bleeding from the gut ends that had been transected. There was no breach in the bowel’s seal. The field was free of enteric contamination. In the post-operative course of these individuals, there was no Roux limb-related morbidity. This procedure is useful because it is cost-effective, time-saving, dependable, and prevents contamination and blood loss. It is also simple to learn and apply.

Swine Small Intestine Sealing Performed by Different Vessel Sealing Devices: Ex-Vivo Test

This study aimed to evaluate the sealing quality of swine small intestine using different laparoscopic radiofrequency vessel sealing devices (two 5 mm: RFVS-1 and -2; one 10 mm: RFVS-3) and a harmonic scalpel (HS) compared to golden standard closure technique. The study was divided into two arms. In study arm 1: n = 50 swine intestinal loops (10 per group) were transected with each instrument and the loops in which the devices provided complete sealing, at the gross inspection, were tested for maximum burst pressure (BP) and histological evaluation and compared to an automatic linear stapler. After the BP tests, the devices that achieved significantly lower BP values were excluded from the second arm. The RFVS-1 and -3 provided statistically significant results and were used in study arm 2, to obtain full-thickness biopsies along the antimesenteric border of the loop and were compared with hand-sewn intestinal closure (n = 30; 10 per group). The biopsies were histologically evaluated for thermal injury and diagnostic features, and intestinal loops tested for BP. RFVS-3 achieved comparable results (69.78 ± 4.23 mmHg, interquartile range (IQR) 5.8) to stapler closing technique (71.09 ± 4.22 mmHg, IQR 4.38; p > 0.05), while the RFVS-1 resulted in significantly (p < 0.05) lower BP (45.28 ± 15.23 mmHg, IQR 24.95) but over the physiological range, conversely to RFVS-2 (20.16 ± 7.19 mmHg, IQR 12.02) and HS (not measurable). RFVS-3 resulted not significantly different (p > 0.05) (45.09 ± 8.75 mmHg, IQR 10.48) than Suture (35.71 ± 17.51 mmHg, IQR 23.77); RFVS-1 resulted significantly lower values (23.96 ± 10.63 mmHg, IQR 9.62; p < 0.05). All biopsies were judged diagnostic. Data confirmed that RFVS-1 and -3 devices provided suitable intestinal sealing, with BP pressures over the physiological range. Conversely, the HS and RFVS-2 should not be considered for intestinal sealing. RFVS devices could be employed to obtain small intestine stump closure or full-thickness biopsies. However, further studies should be performed in live animals to assess the role of the healing process.

The impedance analysis of small intestine fusion by pulse source

The radiofrequency-induced intestine fusion has been widely studied as an alternative for traditional suture in surgery, but fusion quality cannot be evaluated directly. Impedance measurement can evaluate fusion quality, but the relation between impedance and the fusion quality needs optimization for best results. The present study reports the optimum resistance of small intestine fusion. As the feedback signal, resistance was considered the indicator of the fusion completion for the device design of intestine fusion and an in-depth study of microstructure change. A self-design pulse source was used for the small intestine fusion with adjustable voltage, duty ratio, frequency and output time. A frequency of 440 kHz was set, whereas voltage, output time and compression pressure (CP) of the small intestine were independent variables. Different conditions of voltage, CP and time were investigated for achieving the highest burst pressure (BP) measured with a pressure gauge and a peristaltic pump. Each parameter of the equivalent circuit model was calculated by an experimental waveform. Hematoxylin-eosin staining of fusion samples was used for assessing the quality of fusion. The real-time current was measured and recorded during the fusion for the calculation of capacitance and resistance. The highest BP of 38.9 mmHg was achieved with a CP of 900 kPa, a voltage of 50 V and a time of 5 s. Finally, an optimum extracellular resistance range of 61.0-86.2 Ω was found as the optimum resistance for the end of fusion, thus indicating automatic fusion with the best fusion quality.

Use of a bipolar sealing device to seal partial cystectomy with and without augmentation with a single-layer simple continuous suture pattern in an ex vivo canine model

OBJECTIVE

To evaluate the ability of a bipolar sealing device (BSD) to seal canine bladder tissue and to determine the influence of suture augmentation on resistance to leakage of sealed partial cystectomies.

STUDY DESIGN

Ex vivo, simple randomized study.

SAMPLE POPULATION

Urinary bladders harvested from canine cadavers (n = 23).

METHODS

Partial cystectomy of the cranial third of each bladder was performed with a BSD. This seal was augmented with a simple continuous pattern of 4-0 polydioxanone in half of the specimens. A pressure transducer inserted through the ureter measured intraluminal pressure at initial leakage and catastrophic failure as dyed saline was infused via a catheter inserted through the urethra. Initial leakage pressure and pressure at catastrophic failure were compared between sutured and nonsutured sealed partial cystectomies.

RESULTS

Sutured sealed cystectomies showed initial leakage at lower pressures compared to non-sutured cystectomies (8.6 vs. 17.7 mm Hg; P = .0365) but were able to sustain greater pressures at catastrophic failure (34.3 vs. 21.8 mm Hg; P = .007). Catastrophic failure occurred along the seam of all nonsutured sealed cystectomies and at the suture holes in 10 of the 12 sutured bladders.

CONCLUSION

Partial cystectomies were effectively sealed with a BSD in this canine cadaveric bladder model. Augmentation with a simple continuous suture pattern increased the pressure at which catastrophic leakage occurred but lowered initial leak pressure.

CLINICAL SIGNIFICANCE

This study provides evidence supporting the evaluation of BSD use for partial cystectomy in live animals.

Preliminary study of a control algorithm for radio-frequency-induced intestinal tissue fusion

Purpose: A control algorithm for radio-frequency-induced intestinal tissue fusion was developed to explore the effects of different control parameters on intestinal tissue fusion.Materials and methods: Radio-frequency-induced fusion was performed on ex vivo small intestine tissue. The effect on the fusion was observed by changing the control parameters (power, interval time, and terminal impedance) in the algorithm. The quality of fusion was evaluated using the burst pressure and thermal damage measurement. Histological evaluation was used to assess the fusion quality indirectly.Results: A maximum burst pressure of 8.460 ± 0.2674 KPa was acquired when the power was set to 100 W, the interval time was set to 2000 ms, and the terminal impedance was set to 50 Ω. Moreover, the thermal damage range increased with an increase in power but decreased with an increase in the interval time and terminal impedance. Furthermore, the thermal damage range and temperature were presumably related.Conclusions: For an ex vivo small intestine tissue, the appropriate control parameters could be set when the power was approximately 100 W, the interval time was approximately 2000 ms, and the terminal impedance was approximately 50 Ω. This study could provide a basis for the selection of control parameters for intestinal tissue fusion.

Tissue fusion technology versus suture and staple in porcine bowel anastomosis: an in vivo study

The aim of this study was to make a comparison between the tissue fusion technique and conventional methods for sealing bowel anastomosis. Eighteen female domestic pigs (Suidae, Sus) were used in our study. Tissue-fused anastomoses (LigaSure groups) were made in 13 animals (5 anastomoses per animal), which were subdivided into 4 groups according to different manufacturing settings: “LigaSure-L-1” and “LigaSure-L-2”, with low energy output level with 1 or 2 device-activated tissue sealing times, and “LigaSure-M” and “LigaSure-H”, with medium or high energy output level. As controls, automatically stapled (GIA group) and hand-sewn (suture group) anastomoses were utilized in 3 and 2 animals, respectively. There was no statistical difference in the overall leakage rate between the GIA group (6.7%) and the LigaSure groups (15%) (P=1.000). There was less proliferating epithelium covering the anastomosis gap in the LigaSure groups compared with the other two groups. The gap between the two extremities of muscular layers of the anastomosis in the LigaSure groups was filled with collagen fibers. More proliferating cell nuclear antigen (PCNA)-positive cells were found in the anastomoses of the LigaSure groups compared with the other two groups (P=0.010). Our results showed that the tissue fusion technology was a feasible and safe method for anastomoses.

Ex vivo comparison of leakage pressures and leakage location with a novel technique for creation of functional side-to-side canine small intestinal anastomoses

OBJECTIVE

To determine the ability of functional side-to-side small intestinal anastomoses (FSS-SIA) created with an electrothermal bipolar vessel sealing (EBVS) device to resist leakage.

STUDY DESIGN

Experimental, ex vivo.

SAMPLE POPULATION

Jejunal segments (n = 130) from 10 healthy canine cadavers.

METHODS

Four types of anastomoses were created (two segments/construct and 15 constructs/group): EBVS (group A), EBVS + transverse stapling (group B), stapled (group C), and EBVS + suture augmentation (group D). Initial leakage pressure (ILP), initial leakage location (ILL), and maximal intraluminal pressure were compared between groups, and five group A constructs were analyzed histologically.

RESULTS

Initial leakage pressure was greater in group D than in groups A, B, and C (P < .011). There was a difference in ILL among groups (P = .003). Leakage occurred at the side-to-side intestinal anastomosis fusion line in 13 of 15 (87%) constructs for groups A and B and in nine of 15 (60%) constructs for group D. Maximal intraluminal pressure was greater in group C than in groups A, B, and D (P < .004). Histological examination was consistent with collagenous fusion without cavitation defects.

CONCLUSION

Functional side-to-side small intestinal anastomosis was consistently achieved with an EBVS device. Augmentation of EBVS anastomoses with simple interrupted sutures along the anastomotic fusion line increased ILP compared with stapled anastomoses.

CLINICAL SIGNIFICANCE

Despite the success and feasibility of creating an FSS-SIA with an EBVS device, additional in vivo studies are required to determine the effectiveness of intestinal fusion prior to clinical implementation.

Energy-Based Tissue Fusion for Sutureless Closure: Applications, Mechanisms, and Potential for Functional Recovery

As minimally invasive surgical techniques progress, the demand for efficient, reliable methods for vascular ligation and tissue closure becomes pronounced. The surgical advantages of energy-based vessel sealing exceed those of traditional, compression-based ligatures in procedures sensitive to duration, foreign bodies, and recovery time alike. Although the use of energy-based devices to seal or transect vasculature and connective tissue bundles is widespread, the breadth of heating strategies and energy dosimetry used across devices underscores an uncertainty as to the molecular nature of the sealing mechanism and induced tissue effect. Furthermore, energy-based techniques exhibit promise for the closure and functional repair of soft and connective tissues in the nervous, enteral, and dermal tissue domains. A constitutive theory of molecular bonding forces that arise in response to supraphysiological temperatures is required in order to optimize and progress the use of energy-based tissue fusion. While rapid tissue bonding has been suggested to arise from dehydration, dipole interactions, molecular cross-links, or the coagulation of cellular proteins, long-term functional tissue repair across fusion boundaries requires that the reaction to thermal damage be tailored to catalyze the onset of biological healing and remodeling. In this review, we compile and contrast findings from published thermal fusion research in an effort to encourage a molecular approach to characterization of the prevalent and promising energy-based tissue bond.

Cecal Resection with Bipolar Sealing Devices in a Rat Model

Background: Bipolar sealing devices are routinely used to seal blood vessels. The aim of the study is to evaluate the feasibility and safety of colonic sealing with the use of the bipolar energy devices in rats as model for experimental appendectomy. Methods: Seventy-five male Wistar rats underwent a cecal resection with four different bipolar sealing devices or a linear stapler. The harvesting procedure was performed immediately or at postoperative day (POD) 7. The sealing front bursting pressure (BP) was measured in both groups. At POD7, the resection line was clinically examined and the hydroxyproline (HDP) levels were determined. Hematoxylin and Eosin (H&E) staining was used for histopathological evaluation of the sealing front as well. Results: There was no mortality and no insufficiency. The BPs between the bipolar sealing devices showed no statistical differences. The early phase of the seal (POD 0) provides a low BP with an 30.8% increase until POD 7. The BPs in the stapler group showed significant better values. The hydroxyproline levels did not differ statistically between the groups. Histopathologically, there were more signs of ischemic necrosis in the stapler group than in the sealing devices groups. Conclusion: The resection and sealing of the cecum as an experimental appendectomy model with the use of bipolar energy devices proved feasible and safe in rats. The different energy devices in this study produce comparable results. To justify clinical practice in humans, several studies on the underlying mechanisms of early stage wound healing are needed.

Comparison of the safety of electrotome, Harmonic scalpel, and LigaSure for management of thyroid surgery

BACKGROUND

Energy-based surgical devices, including electrotome, the Harmonic scalpel, and LigaSure, have been widely applied in thyroid surgery, although a comparison of their safety and efficacy has not been reported yet. In this study, we investigated the feasibility of using hemostatic energy-based surgical devices during thyroid surgery in a canine model.

METHODS

Twenty-four beagle dogs were randomly divided into the following groups: electrotome (30 kW), electrotome (15 kW), the Harmonic scalpel (output level 3), and LigaSure (middle gear). The hemostatic devices were applied on the thyroid surface for 3 seconds and then near the recurrent laryngeal nerve (RLN; distance of 5 mm, 3 mm, or 1 mm) for 3 seconds. Evoked electromyography (EMG) amplitudes were recorded by intraoperative neuromonitoring (IONM). Acute microstructural morphological damage to thyroid tissues and the RLN were evaluated immediately after the procedure by light and electron microscopy.

RESULTS

Electrotome caused a significant decrease in evoked EMG amplitudes when applied at a vertical distance of 1 mm from the RLN, both at 30 kW (1046 ± 404.3 μV vs 153 ± 245.5 μV; p < .001) and 15 kW (1197 ± 589.2 μV vs 986.3 ± 797.3 μV; p = .037), compared with those evoked under normal conditions. Furthermore, distinct acute microstructural morphological changes of the RLNs were observed by light and electron microscopy. However, no significant functional or histological changes were induced by the electrotome at a vertical distance of 5 mm or 3 mm from the RLN. The Harmonic scalpel and LigaSure induced neither marked changes in evoked EMG amplitudes when applied at vertical distances of 5 mm, 3 mm, or 1 mm (all p > .05) nor microstructural morphological changes in the RLNs. The electrotome (15 kW) caused more serious thermal damage to thyroid tissues than that caused by either the Harmonic scalpel or LigaSure (thermal damaged depth: 0.951 ± 0.061 vs 0.756 ± 0.074, p < .001; 0.951 ± 0.061 vs 0.724 ± 0.116, p < .001). Nevertheless, there were no differences between the Harmonic scalpel and LigaSure groups (p = .435).

CONCLUSION

LigaSure and the Harmonic scalpel might be safer than electrotome when used in thyroid operations. LigaSure generates less heat than the Harmonic scalpel and electrotome. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1078-1085, 2017.

Predicting burst pressure of radiofrequency-induced colorectal anastomosis by bio-impedance measurement

The present study investigates the relationship between bio-impedance and burst pressure of colorectal anastomosis created by radiofrequency (RF)-induced tissue fusion. Colorectal anastomosis were created with ex vivo porcine colorectal segments, during which 5 levels of compression pressure were applied by a custom-made bipolar prototype, with 5 replicate experiments at each compression pressure. Instant anastomotic tensile strength was assessed by burst pressure. Bio-impedance of fused tissue was measured by Impedance Analyzer across frequency that 100 Hz to 3 MHz. Statistical analysis shows only a weak correlation between bio-impedance modulus and burst pressures at frequency of 445 kHz ([Formula: see text]  =  -0.426, P  =  0.099  >  0.05). In contrast, results demonstrated a highly significant negative correlation between reactance modulus and burst pressures ([Formula: see text]  =  -0.812, P  =  0.000  <  0.05). The decrease in mean reactance modulus with increasing burst pressures was highly significant (P  =  0.019  <  0.05). The observed strong negative correlation between reactance modulus and burst pressures at frequency of 445 kHz indicates that reactance is likely to be a good index for tensile strength of RF-induced colorectal anastomosis, and should be considered for inclusion in a feedback loops in devices design.

Lateral thermal damage of mesoappendix and appendiceal base during laparoscopic appendectomy in children: comparison of the harmonic scalpel (Ultracision), bipolar coagulation (LigaSure), and thermal fusion technology (MiSeal)

BACKGROUND

The aim of this study was to compare lateral thermal damage of mesoappendix and appendiceal base using three different instruments for sealing and cutting of mesoappendix.

MATERIALS AND METHODS

A total number of 99 patients (54 males and 45 females) who underwent laparoscopic appendectomy because of suspected appendicitis between December 2013 and May 2015 were enrolled in the study. The patients were divided in three groups based on instrument used for sealing of mesoappendix: group 1 (Ultracision; n = 36), group 2 (LigaSure; n = 32), and group 3 (MiSeal; n = 31). Lateral thermal damage, intraoperative and postoperative complications, duration of surgery, hospital stay, and economic value were compared within groups.

RESULTS

The median age of patients was 14 y (range 3-17). A histopathologic analysis revealed a positive diagnosis of appendicitis in 84 patients (85%). The median lateral thermal damage on appendiceal base using Ultracision, LigaSure, and MiSeal was 0.10 mm, 0.16 mm, and 0.10 mm respectively, and on mesoappendix, 0.08 mm, 0.13 mm, and 0.08 mm, respectively. Significantly higher thermal damage was found on mesoappendix (P = 0.015) and appendiceal base (P = 0.012) in patients treated with LigaSure than in patients from other groups. There were no statistical differences among the groups regarding intraoperative and postoperative complications (P = 0.098). No significant difference in thermal damage between appendicitis and nonappendicitis group was found (P = 0.266).

CONCLUSIONS

Using of Ultracision, LigaSure, and MiSeal for sealing of mesoappendix in laparoscopic appendectomy in children is safe and useful. LigaSure produces significantly greater lateral thermal damage compared with other instruments.

Stapleless laparoscopic sleeve gastrectomy. Preliminary report

BACKGROUND

Laparoscopic sleeve gastrectomy (SG) as a single-stage procedure for the treatment of morbid obesity is becoming increasingly popular. In undeveloped countries, the linear staples required to create the sleeve are not always available because of their high cost. As an alternative to the staples, the bipolar vessel sealer device could be used in bariatric surgery to divide and temporarily seal the stomach.

SETTINGS

Universidad Central de Venezuela, Caracas, Venezuela.

METHODS

Between May 2015 and July 2016, 9 patients with a mean body mass index of 38.2 kg/m² were submitted to a stapleless laparoscopic SG using the bipolar vessel sealer for the gastric division. The sleeve was performed over a 42 French bougie and closed with 2 layers of running sutures. Surgical time, morbidity, hospital stay, and excess weight loss were prospectively collected.

RESULTS

Mean operative time and hospital stay were 117 min and 2.3 days. There was no major morbidity but 2 patients presented a basal atelectasis, which was solved by medical treatment without consequences. After a mean follow up of 6.8 months the mean excess weight loss was 78.4%.

CONCLUSION

The technique of stapleless laparoscopic SG presented in this report is a valid alternative when these devices are not available. Large series with long-term follow-up are necessary to make definitive conclusions.

LAPAROSCOPICALLY ASSISTED ANORECTOPLASTY AND THE USE OF THE BIPOLAR DEVICE TO SEAL THE RECTAL URINARY FISTULA

Background:

The anorectal anomalies consist in a complex group of birth defects. Laparoscopic-assisted anorectoplasty improved visualization of the rectal fistula and the ability to place the pull-through segment within the elevator muscle complex with minimal dissection. There is no consensus on how the fistula should be managed.

Aim:

To evaluate the laparoscopic-assisted anorectoplasty and the treatment of the rectal urinary fistula by a bipolar sealing device.

Method:

It was performed according to the original description by Georgeson¹. Was used 10 mm infraumbilical access portal for 30º optics. The pneumoperitoneum was established with pressure 8-10 cm H₂O. Two additional trocars of 5 mm were placed on the right and left of the umbilicus. The dissection started on peritoneal reflection using Ligasure(r). With the reduction in the diameter of the distal rectum was identified the fistula to the urinary tract. The location of the new anus was defined by the location of the external anal sphincter muscle complex, using electro muscle stimulator externally. Finally, it was made an anastomosis between the rectum and the new location of the anus. A Foley urethral probe was left for seven days.

Results:

Seven males were operated, six with rectoprostatic and one with rectovesical fistula. The follow-up period ranged from one to four years. The last two patients operated underwent bipolar sealing of the fistula between the rectum and urethra without sutures or surgical ligation. No evidence of urethral leaks was identified.

Conclusion:

There are benefits of the laparoscopic-assisted anorectoplasty for the treatment of anorectal anomaly. The use of a bipolar energy source that seals the rectal urinary fistula has provided a significant decrease in the operating time and made the procedure be more elegant.

EXPERIMENTAL INVESTIGATIONS ON INTESTINAL ANASTOMOSIS — A COMPARISON BETWEEN AUTOMATIC AND HAND SUTURING TECHNIQUES

In this research, intestinal anastomosis was compared in hand and automatic suturing. This work is based on two different experiments: The first one is the tensile test with the aim of finding the maximum breaking strength with the elongation rate of 5[Formula: see text]mm/min; and the second one is the fatigue test with a frequency of 0.2[Formula: see text]Hz and the amplitude of 16, 24 and 32[Formula: see text]mm of stretch in each phase to discover the total number of cycles to failure. For this purpose, 42 fresh bovine intestines were used; 21 specimens for the tensile and 21 for the fatigue test. These two tests were compared by two hand sewing techniques: simple continuous and ford interlocking stitches, and one automatic technique, i.e., the lock stitches. Seven samples were examined for each particular technique. The results of the tensile test indicated that the breaking strength of automatic sutured specimens is significantly greater than those of hand sutured specimens ([Formula: see text]). That might be due to the regularity, as the suturing lines by machines are more regular than suturing by hand. In addition, results showed that automatic sutured specimens failed in greater number of cycles than hand sutured specimens in the fatigue test ([Formula: see text]).

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.

Surgical Efficacy Among Laparoscopic Ultrasonic Dissectors: Are We Advancing Safely? A Review of Literature

The specialty of laparoscopy has evolved with the advent of new technologies over the last few years. Energy-based devices and Ultrasonic dissectors are used with a lot of factors in play-including ergonomics and economics during surgery. Here an attempt is based to review the surgical efficacy and safety of these dissectors with importance to plume production and lateral thermal damage. The factors contributing to adversities to the dissectors are also to be noted. The strategy adopted was aimed at finding relevant studies from PubMed from 1995 to 2014. The basic principle of plume production and thermal damage are studied in this review. Factors contributing to the same that can lead to adversities during laparoscopic surgeries are identified. Summarizing key points that increase lateral thermal damage and plume production amongst different ultrasonic shears and suggesting a technique to identify the right balance between the existing dissectors was possible. The RF Device and USS are both useful and widely used and are more safer than monopolar devices. RF Device is considerably slower than USS, as it cannot achieve coagulation and cutting at the same time. Although USS definitely improvises dissection and has less thermal injury than RF Device, the clinical implications in balancing dissection efficacy with hemostasis need to be investigated further. The ideal haemostatic energy-based shear device would be one with excellent hemostatic results and visual acuity while allowing none or minimal thermal energy escape at the point of application. In our current setting, a combined use of both RF and USS device usage as applied in the particular situations has potential.

Comparison of a New High-Frequency Electric Welding System for Intestinal Closure with Hand-Sewn In Vivo Pig Model

BACKGROUND

Various surgical small intestinal anastomosis methods are in current use, but improvements are always desired. Thus, we compared the feasibility, effectiveness, and safety of a new high-frequency electric welding (HFEW) system for sealing the small bowel versus a hand-sewn in vivo pig model.

MATERIALS AND METHODS

The 96 bowel segments of three pigs were randomized to be sutured either by the HFEW-300 PATONMED device (E.O. Paton Electric Welding Institute of the National Academy of Sciences of Ukraine, Kiev, Ukraine) or hand-sewn, and mucosa-to-mucosa fusions were subjected in vivo testing in the pigs. Bursting pressures, suture time, thermal damage, and the temperature of sealed ends were measured.

RESULTS

Segments that had been treated with a hand-sutured ligature or double-sealed with HFEW were compared. Burst pressure was significantly higher in the hand-sutured group than in the HFEW group (136.2 mm Hg versus 75.8 mm Hg, P<.01). All 48 pig small bowels closed by the HFEW-300 generator showed a success rate of 100.0%. The closing time in the HFEW group was significantly shorter (P<.01). The pathological changes of the closed ends were mainly presented as acute thermal- and pressure-induced injuries.

CONCLUSIONS

Outcomes of the current in vivo study suggest that HFEW is an effective and safe method for ligation of the small bowel in pigs.

Histological characteristics of collagen denaturation and injuries in bipolar radiofrequency-induced colonic anastomoses

Bipolar radiofrequency-induced thermo-fusion has been explored as an advanced surgical method for intestinal anastomoses; however, the histological characteristics of collagen denaturation and injuries arising from this process remain unclear. The aim of this study was to investigate the microcosmic changes and tissue damage of fusion regions with various parameters of injury. Ex vivo colons of pigs were fused serosa-serosa on two carrier rings, which were installed on a homemade anastomotic device. Five levels of compressive pressure from 171 to 313 kPa were applied for 5s to fuse the colons under radiofrequency power of 160 W, and then the collagen denaturation of the fused region was examined by transmission electron microscopy. Light microscopy was utilized to observe histological slices that were stained with picrosirius red in order to visualize the tissue injuries under two levels of radiofrequency power (120 vs. 140 W) and operation time (5 vs. 10s). Transmission electron micrographs showed that increased compressive pressure led to thicker denatured collagen fibrils and wider gaps between each collagen fibril. Serosa adhesion regions appeared abundant in collagen. No histological differences were observed when 120 W of power was applied for 5 and 10s. Significant muscle cracking occurred when colons were fused using 140 W for 5s. When the operation time was extended to 10s, 140 W led to tight fusion and less splitting on muscles. These results suggest that higher compressive pressure results in more severe collagen unfolding and also reduces collagen crosslinking in fused colons. Improved radiofrequency power along with operation time could avoid tissue injury upon radiofrequency-induced colonic anastomoses.

Novel concave-convex electrode for colonic anastomoses by radiofrequency thermo-fusion

BACKGROUND

Successful vascular sealing by radiofrequency (RF)-induced tissue fusion is well established. The present study reports on a novel electrode structure design together with its experimental assessment for RF thermo-fusion of porcine colonic segments.

MATERIALS AND METHODS

Two types of electrode were constructed and used in the present study: one with a conventional smooth surface (S) and the other with a novel reciprocating concave-convex (CC) configuration. Finite element modeling was used to study the thermal distribution profile of the CC electrode. Ex vivo porcine colonic segments were used to create end-to-end serosa-to-serosa colonic anastomoses by applying a pulse of 160 W RF power for 20 s. Different compression pressures (S1, S2, S3) and (C1, C2, C3, C4, C5), were applied, via specially designed ring carriers, to the S and CC electrodes, respectively. Assessment was based on anastomotic burst pressures and histological appearances using light microscopy of paraffin sections.

RESULTS

In total, 22 RF-induced circular anastomoses were performed. Similar burst pressures were observed for anastomoses created by the two types of electrodes (S, CC) performed under the same compression pressure. In contrast, significant differences were observed on histological examination of tissue anastomotic site. In particular, fusion areas between gaps of the CC electrode showed normal histological appearance, while the S electrode produced a completely flat featureless appearance. Furthermore, the CC electrode produced significantly different burst pressures depending on the applied compression pressure during thermo-fusion: compression pressures C1 vs. C4 produced circular anastomotic fusions with burst pressures of 21.9 ± 9.3 vs. 44.6 ± 8.9 mmHg, (p = 0.034); but the burst pressure beyond C4, declined significantly, with C4 vs. C5, burst pressures of 44.6 ± 8.9 vs. 24.7 ± 8.0 mmHg, (p = 0.034).

CONCLUSIONS

The CC electrode exhibits larger and faster thermal diffusion profiles resulting in normal histological appearances in the gaps between CC electrode by protecting tissue from mechanical and thermal damage.

The Feasibility of LigaSure to Create Intestinal Anastomosis

Objective. To evaluate the feasibility and the effectiveness of LigaSure Forced Triad to create intestinal anastomosis in an ex vivo porcino model. Methods. Colon samples (n = 100) were prospectively randomized into 2 groups: LigaSure group (n = 90) and Stapler group (n = 10). The LigaSure group was divided into 9 subgroups, each of 10 samples, according to the different power levels of the LigaSure system (Bar 1, Bars 2, and Bars 3) and radiofrequency application (1 application, 2 applications, and 3 applications) used. All anastomoses were tested for early burst pressure. The LigaSure subgroup having the highest burst pressure was compared with the Stapler group. Finally, the specimen was reviewed by the same pathologist. Results. The burst pressures of the 9 subgroups of LigaSure segments were the following: 29.7 ± 4.5 (Subgroup a); 27.4 ± 3.1 (Subgroup b); 25.3 ± 4 (Subgroup c); 32.9 ± 2.3 (Subgroup d); 30.7 ± 3.8 (Subgroup e); 25.7 ± 4.8 (Subgroup f); 42 ± 4.7 (Subgroup g); 31.8 ± 3.8 (Subgroup h); and 28.5 ± 3 (Subgroup j). Subgroup g (3 bars-power levels/1 frequency application) had the highest burst pressure ( P < .001; ANOVA test). No significant difference was found between burst pressure of Subgroup g and Stapler group (42 ± 4.7 vs 42 ± 4.3, respectively, P = .9). On histological view, the LigaSure anastomosis was formed by collagen sealed without cavitation defects. Conclusions. Our study seems to confirm the feasibility of creating intestinal anastomosis using LigaSure. However, further researches in in vivo models are mandatory before recommending its clinical usage in such settings.

Colorectal anastomosis facilitated by the use of the LigaSure(®) sealing device: comparative study in an animal model

BACKGROUND

Recently, there has been speculation about the possibility of fusing intestinal tissue using bipolar sealing devices. In this study we compare in a porcine model the anastomoses created using the LigaSure(®) device with those created with a stapler after section and closure of a rectal stump.

METHODS

Thirty pigs underwent laparoscopic colorectal anastomosis. In group A (n = 15), the division of the intestine and distal stump closure were done with a 10-mm LigaSure Atlas(®) device. In group B, these steps were carried out using an endoscopic stapler. Subsequently, the colorectal anastomosis was performed using circular stapling in both groups. The 4-week follow-up included health status, weight gain, blood tests, X-rays, and colonoscopy. Anastomotic tissue was processed to study the mechanical tensile strength and histopathology.

RESULTS

There was no difference in the rate of conversion to open surgery or in average operating time between the groups. In the sealing device group, there was a significantly higher rate of failure in rectal stump closure (p = 0.042). There was one death in group B due to anastomotic leak. There was no difference in adhesion formation or stenosis. Mid-section anastomosis area was 89.7 mm(2) in group A compared with 100 mm(2) in group B (p = 0.52). In tensile strength studies, the maximum load resisted by the sample was 13.8 ± 4.9 N (group A) versus 15.7 ± 4.4 N (group B) (p = 0.17). There was no difference between the groups in degree of reepithelialization, number of inflammatory cells, or the presence of microabscesses.

CONCLUSIONS

Division and sealing of the rectal stump with the LigaSure(®) device is feasible in the proposed experimental model, but it is less reliable than conventional closure with a stapler, since it has a significantly greater failure rate. Therefore, The LigaSure(®) device should not be used for this purpose in the clinical setting as this could lead to serious and dramatic complications.

Common uses and cited complications of energy in surgery

BACKGROUND

Instruments that apply energy to cut, coagulate, and dissect tissue with minimal bleeding facilitate surgery. The improper use of energy devices may increase patient morbidity and mortality. The current article reviews various energy sources in terms of their common uses and safe practices.

METHODS

For the purpose of this review, a general search was conducted through NCBI, SpringerLink, and Google. Articles describing laparoscopic or minimally invasive surgeries using single or multiple energy sources are considered, as are articles comparing various commercial energy devices in laboratory settings. Keywords, such as laparoscopy, energy, laser, electrosurgery, monopolar, bipolar, harmonic, ultrasonic, cryosurgery, argon beam, laser, complications, and death were used in the search.

RESULTS

A review of the literature shows that the performance of the energy devices depends upon the type of procedure. There is no consensus as to which device is optimal for a given procedure. The technical skill level of the surgeon and the knowledge about the devices are both important factors in deciding safe outcomes.

CONCLUSIONS

As new energy devices enter the market increases, surgeons should be aware of their indicated use in laparoscopic, endoscopic, and open surgery.

Radiofrequency-induced small bowel thermofusion: an ex vivo study of intestinal seal adequacy using mechanical and imaging modalities

BACKGROUND

Bipolar radiofrequency (RF) induced tissue fusion is believed to have the potential to seal and anastomose intestinal tissue thereby providing an alternative to current techniques which are associated with technical and functional complications. This study examines the mechanical and cellular effects of RF energy and varying compressive pressures when applied to create ex vivo intestinal seals.

METHODS

A total of 299 mucosa-to-mucosa fusions were formed on ex vivo porcine small bowel segments using a prototype bipolar RF device powered by a closed-loop, feedback-controlled RF generator. Compressive pressures were increased at 0.05 MPa intervals from 0.00 to 0.49 MPa and RF energy was applied for a set time period to achieve bowel tissue fusion. Seal strength was subsequently assessed using burst pressure and tensile strength testing, whilst morphological changes were determined through light microscopy. To further identify the subcellular tissue changes that occur as a result of RF energy application, the collagen matrix in the fused area of a single bowel segment sealed at an optimal pressure was examined using transmission electron microscopy (TEM).

RESULTS

An optimal applied compressive pressure range was observed between 0.10 and 0.25 MPa. Light microscopy demonstrated a step change between fused and unfused tissues but was ineffective in distinguishing between pressure levels once tissues were sealed. Non uniform collagen damage was observed in the sealed tissue area using TEM, with some areas showing complete collagen denaturation and others showing none, despite the seal being complete. This finding has not been described previously in RF-fused tissue and may have implications for in vivo healing.

CONCLUSIONS

This study shows that both bipolar RF energy and optimal compressive pressures are needed to create strong intestinal seals. This finding suggests that RF fusion technology can be effectively applied for bowel sealing and may lead to the development of novel anastomosis tools.

Comparison of lateral thermal damage of the human peritoneum using monopolar diathermy, Harmonic scalpel and LigaSure

BACKGROUND

New hemostatic technologies are often employed in open and laparoscopic surgery to reduce duration of surgery and complications. Monopolar diathermy, Harmonic scalpel and LigaSure are routinely used in open and laparoscopic surgery for tissue cutting and hemostasis. We compared lateral thermal damage following in vivo application of 3 commonly used instruments.

METHODS

We used monopolar diathermy, Harmonic scalpel and LigaSure to coagulate and divide the peritoneum of patients who underwent median laparotomy. After anesthesia, median supraumbilical laparotomy was performed, and the peritoneum of each patient was coagulated using different devices. Using light microscopy and morphometric imaging analysis, the width of tissue lateral thermal damage was measured from the point of the peritoneal incision.

RESULTS

We included 100 patients in our study. After a peritoneal incision, the mean lateral thermal damage of monopolar diathermy, Harmonic scalpel (output power 3), Harmonic scalpel (output power 5) and LigaSure were 215.79 μm, 90.42 μm, 127.48 μm and 144.18 μm, respectively.

CONCLUSION

The degree of lateral thermal spread varied by instrument type, power setting and application time. LigaSure and Harmonic scalpel were the safest and most efficient methods of tissue coagulation. Monopolar diathermy resulted in the greatest degree of thermal damage in tissues.

Application of high frequency bipolar electrocoagulation LigaSureTM in appendix vermiformis of rabbits with or without acute inflammatory process

PURPOSE: To evaluate the efficacy of the use of LigaSureTM in appendectomy, with or without acute inflammatory process, and to compare with simple ligature and conventional therapy. METHODS: A total of 30 rabbits (Oryctolagus cuniculus) randomly allocated in two groups, group A and B, of 15 animals each were used. The group A without acute appendicitis and the group B with acute appendicitis were submitted to appendectomy. After, the groups were subdivided into three groups, each group containing five rabbits submitted to simple ligature, conventional therapy and application of LigaSureTM. We assessed macroscopic and microscopy parameters of appendiceal stump and operative wound. RESULTS: The group with acute appendicitis that LigaSureTM was applied had fibrosis in 100% of animals, as well as in the other operative techniques used. It suggested that application of LigaSureTM is efficient as other techniques used in healing of appendiceal stump. CONCLUSIONS: The application of LigaSureTM induces the formation of fibrosis in the appendiceal stump. The technique proved efficacy to induce enough fibrous tissue to obstruct leakage of enteric content.

The next step? Use of tissue fusion technology to perform the serial transverse enteroplasty--proof of principle

BACKGROUND

Serial transverse enteroplasty (STEP) is an established procedure for intestinal lengthening and tapering. A gastrointestinal linear stapler is used to taper the bowel sequentially. We report preliminary experience with tissue fusion technology to perform STEP in a porcine model.

METHODS

Four weaned male pigs (mean age, 4 ± 0 weeks; mean weight, 6.8 ± 0.1 kg) first underwent a 60-cm reversed intestinal segment followed by a STEP 4 to 6 weeks later. The LigaSure Impact (Covidien, Valleylab, Tyco Healthcare Group LP, Boulder, CO) was used to perform the procedure. Animals were fed on postoperative day 2 and terminated 1 week later. Morphometric data were collected, and intestinal tissue was obtained for histology.

RESULTS

Mean bowel caliber of 5.1 ± 0.5 cm was tapered to 1.8 ± 0.3 cm post-STEP with a mean increase in the length of the dilated segment of 82% ± 20%. All animals tolerated enteral feeding, and all survived to termination on day 7. Histologic evaluation revealed the zone of tissue fusion to be 7.1 ± 1.5 mm. Masson trichrome, hematoxylin and eosin, and polarized picrosirius red stains demonstrated that the fusion zone was well healed with overlying granulation tissue.

CONCLUSION

This is the first report of the successful application of radiofrequency energy to perform the STEP procedure in animals. Although further evaluation is required, tissue fusion devices may eventually provide an alternative to the linear stapler for the STEP procedure.

Comparison of bipolar electrosurgical devices with ligatures and endoclips in the rat appendicitis model

PURPOSE

The aim of this study is to compare bipolar radiofrequency-driven vessel sealer, bipolar electrocautery, polyglactin 910 sutures, and endoclips in appendiceal stump closure with respect to operative time, appendiceal stump strength, and inflammation in a rat appendiceal model.

METHODS

Forty-eight Wistar-Albino rats, which had previously created appendicitis, were divided into 2 (groups A and B). Each group was further subdivided into 4 subgroups (AL, ABPC, AC, AS, BL, BBPC, BC, and BS) each containing 6 rats. An appendectomy was performed, and the stump was closed by bipolar radiofrequency-driven vessel sealer in the L, bipolar electrocautery in the BPC, endoclips in the C, and ligatures in the S subgroups. Cecum bursting pressures were determined instantly after the operation in group A and on the seventh postoperative day in group B. All operative times were measured. Appendices and appendiceal stumps underwent histopathologic examination. Statistical analyses were performed with Kruskal-Wallis and Mann-Whitney U tests. P < .05 was considered significant.

RESULTS

Bursting pressures of the subgroups were comparable on postoperative immediate period and day 7. Operative times were significantly shorter in the L and BPC subgroups in A and B. Histopathologic examination showed that the inflammation scores were similar in group A. In group B, inflammation parameters were also similar except the necrosis status, which was found to be decreased in BL compared with BC and BS. Necrosis status was significantly lower, and lymphocyte quantity was significantly higher in BL and BBPC compared with AL and ABPC.

CONCLUSIONS

Bipolar radiofrequency-driven vessel sealer and bipolar electrocautery achieve safe stump closure with satisfactory bursting pressure values in an experimental rat appendicitis model. Decreased operative time and unimpaired healing are encouraging.

LigaSure versus conventional dissection technique in pancreatoduodenectomy: a pilot study

BACKGROUND

Pancreatic surgery requires extensive preparation and tissue dissection. Therefore, LigaSure (Valleylab, Boulder, CO) provides an alternative to conventional dissection techniques. The aim of the present study was to describe the feasibility, safety, and cost efficiency of LigaSure in pancreatoduodenectomy.

METHODS

Seven patients underwent surgery with the Ligasure and 7 patients underwent surgery with conventional dissection techniques. The patients were investigated for surgical time, intraoperative blood loss, complications, mortality, duration of hospital stay, and surgery-related costs.

RESULTS

Surgical time was 207 minutes in the LigaSure group and 255 minutes in the conventional group (P = .020). Intraoperative blood loss was 271 and 771 mL, respectively (P = .010). Other perioperative outcomes were comparable. The respective surgery-related costs averaged €4,125 and €4,931 (P = .023).

CONCLUSIONS

The use of LigaSure in pancreatoduodenectomy seems to be feasible and safe. In addition, it might lead to a reduction in the surgery-related costs.

LigaSure compared with ligatures and endoclips in experimental appendectomy: how safe is it?

PURPOSE

The present study aims to compare strength, healing, and inflammation of appendiceal stumps closed by LigaSure Precise (Valleylab, Boulder, CO, USA) device, ligatures using polyglactin 910 (Vicryl, Ethicon, Edinburgh, UK) and endoclips (Ligaclip ERCA, Ethicon, OH, USA), and operation time (OT) in experimental appendectomy.

METHODS

Forty-eight Sprague-Dawley rats were divided into two (Group A and B). Each group was further subdivided into three subgroups (AS, AC, AL, BS, BC, BL) containing eight rats. Appendectomy was performed and stump was closed by ligatures in S, by endoclips in C and by LigaSure in L subgroups. OT was recorded. In Group A, cecum bursting pressures (BP) were determined instantly after the operation. In Group B, BP, histological evaluations, and measurements of collagen contents estimated by the tissue hydroxyproline (HPL) level were made on the seventh postoperative day. Statistical analyses were performed with Kruskal-Wallis test and Mann-Whitney U test. P value was considered significant at less than 0.05.

RESULTS

BPs of subgroups were comparable on postoperative immediate period and day 7. HPLs and OTs were significantly better in L subgroups. BL had the least inflammation.

CONCLUSION

Better healing, less inflammation, shorter OT, and equal strength achieved with LigaSure device comparing with polyglactin 910 ties and endoclips in experimental appendectomy is encouraging.

Optical, thermal, and electrical monitoring of radio-frequency tissue modification

Radio-frequency (rf) tissue fusion involves the sealing of tissue between two electrodes delivering rf currents. Applications include small bowel fusion following anastomosis. The mechanism of adhesion is poorly understood, but one hypothesis is that rf modification is correlated to thermal damage and dehydration. A multimodal monitoring system capable of acquiring tissue temperature, electrical impedance, and optical transmittance at 1325-nm wavelength during rf delivery by a modified Ligasure fusion tool is presented. Measurements carried out on single layers of ex vivo porcine small bowel tissue heated at approximately 500-kHz frequency are correlated with observation of water evaporation and histological studies on full seals. It is shown that the induced current generates a rapid quasilinear rise of temperature until the boiling point of water, that changes in tissue transmittance occur before impedance control is possible, and that a decrease in transmission occurs at typical denaturation temperatures. Experimental results are compared with a biophysical model for tissue temperature and a rate equation model for thermal damage.

Real-time optical monitoring of radio-frequency tissue fusion by continuous wave transmission spectroscopy

Radio-frequency (RF) tissue fusion is a novel method of tissue approximation that can seal tissue without the need for sutures or staples, based on the combined effects of heat and pressure on the apposed tissue surfaces. RF delivery must be controlled and optimized to obtain a reproducible, reliable seal. We use real-time optical measurements to improve understanding of the tissue modifications induced by RF fusion. The main macroscopic transformations are thermal denaturation and dehydration. Light propagation in tissue is a function of both and therefore should provide interesting insight into the dynamic of occurring phenomena. Quantification by continuous wave technique has proven challenging. We proposed an algorithm based on the measurement of the absolute transmittance of the tissue, making use of the modified Beer-Lambert law. The experimental method and the data algorithm are demonstrated by RF fusion of porcine small bowel. The proposed optical measurement modality is well adapted to modern surgical instrumentation used for minimally invasive procedures.