Yasuto Sakaguchi

Development of a novel tissue-engineered nitinol frame artificial trachea with native-like physical characteristics

Background Tracheal reconstruction is complicated by the short length to which a trachea can be resected. We previously developed a biocompatible polypropylene frame artificial trachea, but it lacked the strength and flexibility of the native trachea. In contrast, nitinol may provide these physical characteristics. We developed a novel nitinol frame artificial trachea and examined its biocompatibility and safety in canine models. Methods We constructed several nitinol frame prototypes and selected the frame that most closely reproduced the strength of the native canine trachea. This frame was used to create a collagen‐coated artificial trachea that was implanted into 5 adult beagle dogs. The artificial trachea was first implanted into the pedicled omentum and placed in the abdomen. Three weeks later, the omentum‐wrapped artificial trachea was moved into the thoracic cavity. The thoracic trachea was then partially resected and reconstructed using the artificial trachea. Follow‐up bronchoscopic evaluation was performed, and the artificial trachea was histologically examined after the dogs were sacrificed. Results Stenosis at the anastomosis sites was not observed in any dog. Survival for 18 months or longer was confirmed in all dogs but 1, which died after 9 months due to reasons unrelated to the artificial trachea. Histological examination confirmed respiratory epithelial regeneration on the artificial tracheas luminal surface. Severe foreign body reaction was not detected around the nitinol frame. Conclusions The novel nitinol artificial trachea reproduced the physical characteristics of the native trachea. We have confirmed cell engraftment, good biocompatibility, and survival of 18 months or longer for this artificial trachea in canine models.

Development of a novel lung-stabilizing device for VATS procedures

BackgroundThe use of video-assisted thoracoscopic surgery (VATS) has substantially increased in recent years. These procedures involve the insertion of specialized devices into the thoracic cavity via access ports. However, conventional devices such as cotton-tipped applicators and graspers can limit the field of view and injure the fragile lung tissue. The aim of this study was to develop a novel lung-stabilizing device for VATS that provides a good surgical field of view without causing lung injury.MethodsWe developed a novel suction-based lung-stabilizing device equipped with three hemispheric 20-mm-diameter silicon suction cups. The utility and safety of the novel device were evaluated using a resected pig lung and canine models. In order to assess potential organ damage arising from the use of the novel device, canine lung parenchyma and pleura were macroscopically and microscopically examined after the device had been continuously applied under negative pressure conditions of −400 or −540xa0mmHg for 1xa0h.ResultsTo assess the utility of the novel device, we performed lobectomies in the resected pig lung and VATS in canine models. The device demonstrated sufficient power to stabilize the lungs and provided a clear field of view during surgery, which enabled us to perform VATS lobectomies more easily than conventional stabilizing forceps. Assessment of the dogs’ lungs immediately after detaching the suction-based device revealed no complications such as hemorrhage, air leaks, and bullae formation. Pathological examination after 7xa0days also showed no substantial damage, except for a small impression in the parenchyma and pleura of the surface layer where the device had contacted the lung tissue.ConclusionsAlthough further validation studies in clinical settings are required, our study indicates that the novel lung-stabilizing device has potentially useful applications in VATS procedures.

Intrabronchial Foreign Body Extracted With Tranilast and Corticosteroid

We present a case of intrabronchial foreign body buried in granulation tissue, which was successfully extracted administrating tranilast (n-[3,4-dimethoxycinnamoyl] anthranilic acid), suppressing collagen synthesis by fibroblasts in keloid and hypertrophic scars, and corticosteroid. Bronchoscopy of a 74-year-old man showed the nail was buried in reactive granulation tissue and could not be observed from the surface. Tranilast at 300 mg/day and methylprednisolone at 250 mg/day were prescribed for 4 days, followed by a reduction of the corticosteroid to 40 mg/day for 3 days. Seven days later, the granulation tissue and mucosal edema were diminished, and the nail was successfully extracted.

Three-dimensional Navigation for Thoracoscopic Sublobar Resection Using a Novel Wireless Marking System

We developed a novel localization technique for small intrapulmonary lesions using radiofrequency identification (RFID) technology. Micro-RFID markers with nickel-titanium coils were designed to be placed from subsegmental bronchi to the peripheral parenchyma. In this preclinical study, thoracoscopic subsegmentectomy of a canine pseudotumor model was performed to demonstrate the feasibility and three-dimensional positional accuracy of the system. To recover subcentimeter pseudotumors, markers were bronchoscopically placed to determine the resection line: (1) next to the pseudotumor; (2) in the responsible subsegmental bronchi as the central margin; and (3) on the intersubsegmental plane as the lateral margin. Specific marker positions were located by wireless communication using a wand-shaped probe with a 30-mm communication range, with the distance to the marker indicated by gradual changes in sound pitch. Thirty-four markers were placed for 10 pseudotumors (14.6u2009mm from the pleura) in 10 canines. Three markers were placed at a mean distance of 5.5u2009mm from the pseudotumors, and 11 central and 20 lateral markers were placed at mean distances of 17.2 and 20.7u2009mm from the pseudotumors, respectively. Central markers (20.5u2009mm from the pleura) were detected within 16.0 seconds in 2.9-mm-diameter bronchi. All resection stumps were within 5.4u2009mm (range 2-8u2009mm) from each marker, and pseudotumors were removed with adequate surgical margins toward the central (11.5u2009mm; range 7-16u2009mm) and lateral (12.4u2009mm; range 9-17u2009mm) directions. RFID wireless markers provided precise three-dimensional positional information and are a potential viable alternative to conventional markers.

Thoracoscopic partial resection without using a stapler. (complete republication)

Thoracoscopic partial pulmonary resection for small peripheral nodules without using a stapler has been introduced to our hospital. After partial resection was performed with electrocautery, two different methods of surface sealing were used: a coagulation method (C method) with Soft Coagulation alone, and a coagulation-suturing method (CS method) with Soft Coagulation combined with continuous suturing. The clinical outcomes of the two methods were retrospectively compared in this study. The C method was used in 19 lesions of 18 cases, and the CS method was used in 20 lesions of 19 cases. Primary lung cancer was the most frequent diagnosis (22 lesions of 21 cases). There were no differences between the two groups in the size and depth of the lesions. Operative time was longer with the CS method than with the C method. Postoperative air leakage was a complication in 4 cases with the C method, and one of them required re-do surgery, whereas only one case with the CS method had temporary air leakage. Postoperative computed tomography showed cavitation in 3 C method cases and 5 CS method cases, all without related symptoms. There were no local recurrences at resected sites. In conclusion, the C method was technically easy to perform, but air leakage may be prolonged after surgery. The CS method may have the advantage of causing less air leakage than the C method, but mastering the technique is important to shorten operative time.

Localizing small lung lesions in video-assisted thoracoscopic surgery via radiofrequency identification marking

BackgroundTo facilitate accurate localization of small lung lesions in thoracoscopic surgery, we employed a micro-radiofrequency identification tag designed to be delivered through the 2-mm working channel of a flexible bronchoscope. This report presents the results of preclinical studies of our novel localizing technique in a canine model.MethodsTo evaluate functional placement, three types of tags [Group A, tag alone (nxa0=xa018); Group B, tagxa0+xa0resin anchor (nxa0=xa015); and Group C, tagxa0+xa0NiTi coil anchor (nxa0=xa015)] were bronchoscopically placed in subpleural areas and subsegmental bronchi via our new delivery device; tags were examined radiographically on days 0–7 and day 14. In addition, eight tags, which were placed at a mean depth of 13.3xa0mm (range 9–15.7xa0mm) from visceral pleura in bronchi with a mean diameter of 1.46xa0mm (range 0.9–2.3xa0mm), were recovered by partial lung resection under video-assisted thoracoscopic surgery using a 13.56-MHz wand-shaped probe with a 30-mm communication range.ResultsPeripheral airway placement: Group C had a significantly higher retention rate than the other two groups (retention rate at day 14: Group A, 11.1xa0%; Group B, 26.7xa0%; Group C, 100.0xa0%; Pxa0<xa00.0001). Central airway placement: Overall retention rate was 73.3xa0% in Group C, and placement was possible in bronchi of up to 3.3xa0mm in diameter. Outcomes of partial resection: Tag recovery rate was 100xa0%, mean time required for tag detection was 10.8xa0s (range 8–15xa0s), and mean surgical margin from the delivered tag was 9.13xa0mm (range 6–13xa0mm).ConclusionRadiofrequency identification marking enabled accurate localization with depth, which could ensure effective deep resection margins.

Development of novel force-limiting grasping forceps with a simple mechanism

OBJECTIVESnIn endoscopic surgery, fragile tissues may be damaged by the application of excessive force. Thus, we developed novel endoscopic forceps with a simple force-limiting mechanism.nnnMETHODSnThe novel forceps were constructed with a leaf spring, and the spring thickness determines grasping pressure. We established an evaluation system (maximum score is 11 points) for lung tissue damage leading to complications. We tested the conventional forceps (186.8u2009kPa) and 3 novel spring forceps with the following thicknesses: 1.3u2009mm (53.0u2009kPa), 2.2u2009mm (187.7u2009kPa) and 2.8u2009mm (369.2u2009kPa). After grasping, peripheral canine lung tissues were microscopically examined for acute- and late-phase damages.nnnRESULTSnIn the acute phase (20 sites), the novel forceps caused capillary congestion and haemorrhage in the subpleural tissue, whereas the conventional forceps caused deep tissue and pleural damages. In the late phase (30 sites), both forceps caused fibroblast formation and interstitial thickening, which progressed to the deeper tissues as grasping pressure increased. In the acute phase, the median scores were 2.0 and 6.0 for the novel and conventional forceps, respectively (Pu2009=u20090.003). In the late phase, the median scores were 2.0, 2.5 and 5.0 for 1.3-, 2.2- and 2.8-mm thick forceps, respectively, and 5.0 for the conventional forceps (Pu2009<u20090.001). In both phases, the novel forceps with grasping pressure set below 187.7u2009kPa (2.2u2009mm) caused significantly less lung tissue damage than the conventional forceps.nnnCONCLUSIONSnThe novel endoscopic forceps are able to regulate the tissue-grasping pressure and induce less damage in lung tissues than conventional forceps.