Hiroaki Osada

Experimental study of a new tracheal prosthesis: Pored Dacron tube

OBJECTIVE This study was designed to evaluate how various sizes and densities of pores in Dacron tubing might enhance its utility as a tracheal prosthesis. METHODS A vascular prosthesis made of knitted external velour polyester was prepared for pore formation with a laser. The first set compared different pore sizes (300, 500, and 700 microm) and pore densities (25/cm(2) or 100/cm(2)). Grafts were reinforced with an externally heat-sealed silicone ring. The second set tested grafts with a pore density of 64/cm(2) and a pore size of 500 microm internally reinforced with a stainless-steel spiral stent. In all experiments, a canine mediastinal trachea 10 cartilage rings in length was resected, and the prosthesis was then implanted with an omental flap. RESULTS Lower pore size and density (300 microm, 25 pores/cm(2)) led to essentially no tissue ingrowth. Larger pore size (700 microm) and low density (25 pores/cm(2)) led to rapid and excessive ingrowth of granulation. Midrange pore size (500 microm) and high density (100 pores/cm(2)) invited steady tissue ingrowth, but marked luminal stenosis eventually developed. Stent-reinforced prostheses with 500-microm pores at 64 pores/cm(2), as used in the second set, maintained an average patency rate of 60% or more (range, 20%-100%) at least 12 months after implantation. CONCLUSION Our data show that porosity is a key factor for tissue growth through our Dacron tracheal prostheses. This artificial trachea model has led to long-term survivors up to 27 months after the operation and seems promising as a basic model for clinical tracheal repair.

Efficacy and complications of the Gianturco-Z tracheobronchial stent for malignant airway stenosis.

Purpose: To describe our experience using the Gianturco Z-stent (G-Z stent) for the management of malignant tracheobronchial stenosis, with special reference to complications.Methods: Thirty-six stents were used in 22 patients with 28 lesions. Thirteen patients were grade 5 according to the Hugh-Jones classification. The technical success rates, follow-up results, and complications were reviewed on the basis of the patients’ charts and radiographs.Results: All stents were successfully placed in the ideal position without procedure-related complications. After the procedure, respiratory status improved in 95% (21/22) of patients, and performance status improved in 77% (17/22). Mean survival after stent placement was 15 weeks. Four patients suffered from increased thick secretions requiring multiple suctioning and aspiration by bronchoscopy. One of these patients died from asphyxiation 2 weeks after placement. Stent disruption and/or migration was observed in six patients. Of these six, four experienced life-threatening hemoptysis; all four had received aggressive anticancer treatment.Conclusion: G-Z stents are useful for palliation of malignant tracheobronchial obstruction. However, complications of stent strut fracture and migration give cause for concern.

Surgically treated Swyer-James syndrome

Because patients with Swyer-James syndrome have almost always been treated conservatively, few reports exist of pathological findings of the lung in this syndrome. We report a case of this rare disease treated surgically and discuss pathological findings. A 36-year-old woman repeatedly contracted bronchitis and pneumothorax since adolescence, until April 26, 1997, when she reported chest pain and dyspnea. Chest X-ray on admission showed left pulmonary collapse with a slight deviation of the mediastinum toward the right. Chest computed tomography showed an apical bulla and emphysematous change in the left upper lobe. Pulmonary arteriography at age 17 showed hypoplasia of left pulmonary artery branches in the left upper lobe. Based on a diagnosis of Swyer-James syndrome, we conducted left upper lobectomy on May 2, 1997. Pathological examination of the resected left upper lobe showed marked emphysematous change, including an emphysematous bulla with destruction of alveolar structure and peribronchiolar fibrosis. No vascular abnormality was recognized in histology. Emphysematous change secondary to repeated bronchiolitis is believed to have led to her repeated pneumothorax.

Comparison of bioabsorbable materials for use in artificial tracheal grafts

Limited information exists regarding the usefulness of bioabsorbable materials in the design of tracheal grafts. The aim of this study was to evaluate the feasibility of three bioabsorbable materials for use as artificial trachea. Three sets of grafts were prepared: Group 1 (n=6), knitted polyglactin 910 mesh; Group 2 (n=3), copolymer of L-lactide and epsilon-caprolactone sponge reinforced with polyglycoride fibers; and Group 3 (n=8), copolymer of L-lactide and epsilon-caprolactone sponge covered with knitted poly-L-lactide mesh. All grafts were internally reinforced with a titanium stent. A 10-cartilage-ring-length of canine mediastinal trachea was resected and replaced by a bioabsorbable prosthesis with the aid of an omental flap. In Groups 1 and 2, the patency rates decreased below 50% within two months after surgery. In Group 3, six of eight dogs maintained patency rates above 50% from 10 months to 2 years after surgery. Grafts prepared with a copolymer of L-lactide and epsilon-caprolactone sponge covered with knitted poly-l-lactide mesh (Group 3) can function for up to two years after surgery. These results provide evidence toward the feasibility of utilizing bioabsorbable materials as a tracheal prosthesis.

The role of mediastinal and multi-organ CT scans in staging presumable surgical candidates with non-small-cell lung cancer.

In order to evaluate the role of CT scan and bone scan in staging patients with non-small-cell lung cancer presumably indicated for surgery, 70 consecutive patients who underwent thoracotomy were reviewed. Most of them received mediastinal and multi-organ (brain, liver and adrenal) CT scans and a bone scan. In the most recent 40 of the 70 patients, CT findings of the mediastinal lymph nodes were compared to the pathology following complete sampling. The overall accuracy of the mediastinal CT was 60.0 per cent (12 true positive and 12 true negative), but the negative predictable value was 12/(12+3) or 80.0 per cent, whereas 3 were false negatives though they showed an acceptable postoperative course. Sixteen out of 21 patients with one, or at the most, three enlarged nodes detected on CT also did well postoperatively and retrospectively, were considered not to have required mediastinoscopy. A group of patients showing no, or at the most, three enlarged mediastinal lymph nodes on CT may be considered as candidates for surgery even without mediastinoscopy. Multi-organ survey by means of CT was believed cost-ineffective and omittable. Bone scan however, retrospectively detected three true positives among 20 patients with a positive uptake, so that it cannot be omitted out of hand, though further examination of this point is required.

Dumbbell neurogenic tumor of the mediastinum: A report of three cases undergoing single-staged complete romoval without thoracotomy

Of a total thirteen patients who underwent surgery for a neurogenic tumor in the posterior mediastinum 4 (30.8 per cent) presented with dumbbell type development of the tumor. Along with a comparatively greater incidence in the number of cases of dumbbell neurogenic tumors in the posterior mediastinum, resection has also recently become more popular, necessitating the establishment of a standard operative approach for this type of tumor. We successfully removed dumbbell neurogenic tumor from the posterior mediastinum in our 3 most recent casesvia a dorsal approach by virtue of a laminectomy and resection of a small portion of the neighbouring rib root without opening the parietal pleura at all. These three aptients were a 14 year old female, a 54 year old male and a 68 year old female, respectively, and the largest diameter in cm and level of origin of the tumors were 5.5 at Th 1 in case 1, 3.0 at Th 2 in case 2 and 3.7 at Th 11 in case 3. The operative approach described herein was easy to perform, felt secure and was less invasive and better tolerated by the patients than the thoractomy approach. Avoiding a thoractomy in such cases has many advantages to enumerate, but does not seem to have been clearly aimed at by others to date. We therefore propose our technique as a standard approach for dumbbell neurogenic tumors in the posterior mediastinum.

Cost-effectiveness associated with the diagnosis and staging of non-small-cell lung cancer.

OBJECTIVE We evaluated how much time and money could be saved without compromising overall results in treating lung cancer. SUBJECTS AND METHODS We retrospectively evaluated 318 patients for T- and M-factors and 335 for N-factor. If bronchoscopy failed to diagnose a mass lesion believed to be malignant in x-ray computed tomography (CT), we proceeded to direct thoracotomy without needle or video-assisted biopsy. When mediastinal nodes were negative in CT, we proceeded to direct thoracotomy without mediastinoscopy. We searched routinely for distant metastasis with brain and abdominal CTs and bone scans. RESULTS Lesions suspected of malignancy in CT were pathologically malignant in 93%. A total of 82.8% of patients with CT-negative mediastinum were without metastasis. The remainder, with metastasis, had a postoperative 5-year survival of 23.5%. Brain CT scans were positive in only 2.2%, abdominal CT scans in 2.4%, and bone scans in 5.0%, for patients with a cT1/T2 non-cN2 lesion. CONCLUSION Brain and abdominal CT scans and bone scans may be omitted for cT1/T2 and non-cN2 lesions in CT. CT-negative mediastinum then leads to direct thoracotomy. The vast majority of patients may thus undergo surgery earlier with less physical and financial burden. The cost saving was calculated to be 59.4% per cT1/T2 non-cN2 patient, or US

Experimental tracheal reconstruction with a rotated right stem bronchus

666,815, for population evaluated based on cost-effectiveness.

Etiologic value of p53 mutation spectra and differences with histology in lung cancers.

BACKGROUND To reconstruct a longer tracheal defect, a safe method other than end-to-end anastomosis is necessary. METHODS Nine mongrel dogs underwent right thoracotomy. The lobes of the right lung other than the apical lobe were resected, keeping the bronchi in place to be manipulated to extend the right stem bronchial conduit. The trachea was resected for a 10-cartilage-ring length. The modified right stem bronchus was then brought into the mediastinum by rotation in the frontal plane. An end-to-end anastomosis was made. The right apical lobe, once separated, was then reanastomosed end-to-side. Ciliary transport was studied. RESULTS Eight of the 9 dogs tolerated the surgical procedure well, and the reanastomosed right apical lobe remained well expanded for 1 year or more postoperatively. The inverted segment did not show any cranial ciliary transport movement. CONCLUSIONS A large tracheal defect more than 10 rings in length can be reconstructed using a rotated right stem bronchus with the right apical lobe reanastomosed. The inverted bronchial segment loses its cranial ciliary transport movement.

Reconstruction of the Hemidiaphragm and Hemipericardium Using Combined Reversed Latissimus Dorsi and Serratus Anterior Muscle Flaps

A total of 297 resected Japanese non‐small cell lung cancers (74 squamous cell carcinomas and 223 adenocarcinomas) were analyzed to evaluate the validity of the p53 mutation spectrum as a fingerprint for mutagenic substances as etiological factors. Frequencies of G→T transversions in smokers were significantly higher than in non‐smokers (P = 0.003) and the average incidence of G→T at hot spot codons of adduct formation was higher than that in other codons in smokers and in the hot spots in non‐smokers. Further, the mutation showed a marked strand bias. G→A transitions at CpG sites (CpG→CpA) were equally distributed in smokers and non‐smokers, and on both strands. A→G transitions did not show any variation with smoking status in terms of frequency, but exhibited a marked strand bias. Taken together, the G→T may be a fingerprint of direct mutagenic action of tobacco‐related compounds, the A→G being a new marker for other environmental chemicals, while the CpG→CpA may be attributable to endogenous spontaneous mutation, for active in lung carcinogenesis. (Cancer Sci 2008; 99: 287–295)