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Biomedical subjects

V Tsang

Publications and source records attributed to V Tsang.

At least 37 records · Page 2Linked to original sources
PubMed1997

Percutaneous gastrostomy in radiologic practice.

Long-term gastrostomy tubes have a well-accepted role in providing nutritional support. Traditionally they have been placed by surgeons and by endoscopists. In the last decade, radiologists have come to play a major role in the placement of gastrostomy and gastrojejunostomy devices, and can usually do so as effectively and at lesser expense. A technique for placement is outlined, with a discussion of patient selection and complications. A review of the literature is provided.

Contraindications↗
PubMed1996

The use of radiologically placed gastrostomy tubes in head and neck cancer patients receiving radiotherapy.

PURPOSE: Patients undergoing radiotherapy to the head and neck area frequently experience radiation reactions that can markedly restrict oral intake, require hospitalization, and occasionally cause treatment interruptions. The Vancouver Cancer Center (VCC) has recently employed radiologically placed gastrostomy tubes (G-tubes) in the management of this problem. A review of the patients on whom this procedure had been performed is the subject of this review. METHODS AND MATERIALS: Thirty-four patients had gastrostomy tubes inserted under radiologic guidance. This group is compared to a control group matched for age, sex, irradiated volume, and radiation dose, who did not have gastrostomy tubes. Patients with gastrostomy tubes were divided into two categories: (a) patients who had tubes inserted in anticipation of severe reactions, and (b) patients who developed severe radiation reactions necessitating nutritional support. RESULTS: The gastrostomy group consisted of 65% males with an average age of 59 years and stage range of II (12%), III (24%), and IV (65%). In both the elective group and the nonelective group, patients maintained their weight at 95 to 97% of the pretreatment weight, at follow-up of 6 weeks and 3 months. This compared with an average weight loss in the control group of 9% at 6 weeks and 12% at 3 months. The length of hospitalization was a mean of 4.9 days in the elective group and 19 days in the nonelective group. Complication were low compared to those documented in the literature, but included two tube migrations, two aspirations, and one gastrointestinal bleed. CONCLUSIONS: We believe that gastrostomy tubes contribute significantly to the management of patients with head and neck cancer, particularly in maintanence of nutrition, and they may decrease the need for hospitalization.

Enteral Nutrition↗
PubMed1995

Use of larger sized aortic homograft conduits in right ventricular outflow tract reconstruction.

Between 1973 and 1993 sixty aortic homograft valved conduits in fifty-six patients were used to establish continuity between the right ventricle and the pulmonary artery in congenital heart disease. Age range was one day to 23.5 years (median 3.6 years) which included twenty-six patients less than one-year-old. Conduit size ranged from 11 to 23 mm (median 17.6 mm). there were nine hospital deaths and eight late deaths. The 45 survivors have been followed for a median of 8.6 years (range 6 months to 20 years). All patients have had serial echocardiographic assessments and 35 have had post repair cardiac catheterization. Almost all patients had mild-to-moderate degrees of homograft regurgitation. There were eleven with severe homograft regurgitation and two are being considered for reoperation. The follow up homograft gradient ranged from 0 to 64 mmHg (mean 24 mmHg). Freedom from reoperation for conduit obstruction was 98.2% at five years falling to 91% (C.L. 82%-100%) at 10 years. Of the 23 homografts inserted more than 10 years ago, only one (4.3%) has been replaced because it was causing important obstruction. None have been replaced for regurgitation. Our results indicate that larger sized aortic homografts used in reconstruction of the right ventricular outflow tract give satisfactory results and there is a low incidence of reoperation for replacement at medium term follow up.

Aortic Valve↗
PubMed1994

Human subcutaneous Taenia solium cysticercosis in an Andean population with neurocysticercosis.

Subcutaneous involvement by the larval stages of the pork tapeworm Taenia solium in patients suffering from neurocysticercosis (neurocysticercosis) is well-described. It has been a clinical but undocumented impression that subcutaneous nodules are less common in cases of neurocysticercosis in Latin American than in Africa or Asia. We report on the absence of subcutaneous nodules found in a screened population of 2,891 residents of an Andean village in Ecuador with a prevalence rate for neurocysticercosis of 144 per thousand. Thirty-four patients with multiple intracranial calcifications and or cystic or encephalitic parenchymal lesions of neurocysticercosis were examined and questioned about subcutaneous nodules. Only one patient described nodules and this computed tomography plain films are presented. Several hypotheses are presented as to why nodules may be less common in this Andean community with a high prevalence of neurocysticercosis.

Adolescent↗
PubMed1993

Assessing Photofrin uptake in atherosclerosis with a fluorescent probe: comparison with photography and tissue measurements.

The purpose of this study was to assess Photofrin porfimer sodium (P*) concentration in atherosclerotic plaque (ASP) using a fluorescence detector (Fluoroprobe) compared with fluorescent photography and chemical extraction of P*. ASP was created in the aortoiliac segments of Yucatan miniswine by a combination of balloon endothelial injury and 2% cholesterol and 15% lard diet for 7 weeks. At that time, swine were given P* I.V. in one of the following single dosages: Group I, 2.5; Group II, 1.0; or Group III, 0.5 mg/kg. Swine were sacrificed 24 hours later and aortoiliac and control carotid artery segments removed. Fluorescence was determined from these segments using photographic techniques, the Fluoroprobe, and a spectrofluorometer after chemical extraction. ASP were identified in all swine using photography and the Fluoroprobe. The intensity of fluorescence measured with the Fluoroprobe for Groups I to III was 1,098 +/- 524, 471 +/- 337, and 295 +/- 173 units, respectively (P < 0.01). The tissue concentration of P* in ASP from each group was 130.4 +/- 82.7, 10.0 +/- 1.2, and 9.1 +/- 0.6 ng/g, respectively (P < 0.01). There was a linear correlation between the fluorescence intensity measured with the Fluoroprobe and the extracted tissue concentration (r = 0.88, P < 0.0001). This study showed that a fluorescent detector such as the Fluoroprobe accurately detects the uptake of P* into atherosclerotic plaque.

Animals↗
PubMed1993

Determining the optimal dose of Photofrin in miniswine atherosclerotic plaque.

The purpose of this study was to determine the lowest dose of Photofrin (P) that would produce a 3:1 or greater ratio between atherosclerotic (AS) and control arterial walls. Aortoiliac AS was created in 24 Yucatan miniswine by a combination of balloon endothelial injury and 2% cholesterol and 15% lard diet for 7 weeks. Arteriography was then performed to demonstrate AS lesions. Following this, swine were given intravenously P in one of the following single dosages: 2.5, 1.0 or 0.5 mg/kg. Twenty-four hours later, swine were sacrificed and aortoiliac and control carotid artery segments removed and photographed with ultraviolet light to differentiate fluorescent from nonfluorescent areas. Arterial specimens were submitted for histologic analysis and chemical extraction for determination of fluorescence using a spectrofluorometer. Tissue concentration (ng/g tissue) of P from AS vessels were: Group I, 130.4 +/- 82.7; Group II, 10.0 +/- 1.2; and Group III, 9.1 +/- 0.6, respectively (P < 0.05). Ratios of P concentration in AS: control vessels were: Group I, 8.1 +/- 13.7; Group II, 1.1 +/- 0.2; and Group III, 0.9 +/- 0.1, respectively (P < 0.05). These results demonstrated that a P dose of 2.5 mg/kg provided at least a 3:1 ratio between AS: control artery wall.

Animals↗
PubMed1993

Tracheal approach to pulmonary artery sling associated with funnel-shaped tracheal stenosis.

Pulmonary artery sling with concomitant funnel-shaped tracheal stenosis is a rare but potentially lethal congenital condition. Conventional surgical division and reanastomosis of the aberrant left pulmonary artery to the main pulmonary artery carries a high risk of postoperative ventilatory difficulty from an uncorrected tracheal stenosis. A primary tracheal approach via a right thoracotomy without pulmonary bypass is described.

Bronchoscopy↗
PubMed1992

Intermediate-term results of heart-lung transplantation for cystic fibrosis.

Between September, 1984, and March, 1991, 79 patients underwent heart-lung transplantation for end-stage cystic fibrosis at the Harefield Hospital. Short-term outcome has already been reported, and we now present intermediate-term results. The overall actuarial patient survival was 69% at 1 year, 52% at 2 years, and 49% at 3 years. 17 patients had diabetes mellitus with a survival of 62% to 1 year and 51% to 2 years. 23 patients had one or more other possible high-risk factors, and survival of these patients was 64% at 1 year and 57% at 2 years, compared with 71% and 49%, respectively, in the low-risk group (n = 56). Pseudomonas aeruginosa infection was the most common respiratory infection encountered postoperatively. 92% of patients had at least one episode of acute rejection during the first 3 postoperative months. Lung function was greatly improved after transplantation, the mean forced expiratory volume in 1 s and forced vital capacity increasing from 22% and 35% predicted, respectively, preoperatively to 68% and 70% predicted, respectively, by the sixth postoperative month. This improvement was maintained at 1, 2, and 3 years after transplantation. Lymphoproliferative disorders (4 patients) were successfully treated. Obliterative bronchiolitis developed in 17 patients and the cumulative probability of getting this complication at 1, 2, and 3 years postoperatively was 17%, 23%, and 48%, respectively. Overall, 7 patients were retransplanted. There was no coronary artery disease in the 37 patients who underwent coronary angiography at 1 year, 14 at 2 years, and 9 at 3 years after surgery. 58 patients donated their hearts for subsequent "domino" heart transplantation. Our 5 1/2-year experience with heart-lung transplantation is encouraging but the shortage of donor organs and the complication of obliterative bronchiolitis are the two main obstacles to be overcome.

Adolescent↗
PubMed1992

Use of endotracheal silicone stents for relief of tracheobronchial obstruction.

In this article we describe our initial experience with bifurcated and longitudinal silicone stents that can be inserted entirely endoscopically. A total of 10 patients were stented; half had upper airways obstruction resulting from malignant disease and half had anastomotic obstruction after single-lung (3 patients), double-lung (1 patient), or heart-lung transplantation (1 patient). All patients derived immediate relief of life-threatening stridor. Stents were in place for between 5 days and 2 1/2 years (mean, 232.9 days). In the patients with malignant disease, the stents have provided effective relief from stridor for the remainder of their lives. In the transplant recipients, the medium-term results are encouraging, with the stents providing effective relief from stridor, although the longitudinal stents have been associated with distal migration, requiring that the stents be replaced on up to five occasions. The stents have not been associated with infection in the nonimmunosuppressed patients, and during the relatively short follow-up period there has been no tissue reaction to the material.

Adult↗
PubMed1992

Sequential silastic and expandable metal stenting for tracheobronchial strictures.

The risks and limitations of surgical resection and reconstruction for tracheobronchial strictures demand consideration of other therapeutic options that can alleviate the distressing symptoms of tracheobronchial obstruction. One alternative is to stent the obstructive lesion until surgical advances allow primary reconstruction or replacement of the critically diseased airway or until an ideal endoprosthesis is found. The latter requires uniformity in the distribution of expansile force, conformability and stability within the tracheobronchial tree, and ease of placement. Here we report our experience with the placement of expandable metal stents (Wall-stent) used in conjunction with our Silastic (Dow Corning) endobronchial stents in 5 patients with recurrent tracheal or bronchial strictures. The major site of obstruction was the trachea in 1 patient and a main bronchus or both bronchi in 4 patients. Three patients had a benign bronchial stricture (anastomotic stricture in 2, idiopathic polychondritis in 1), and 2 patients had an obstructive airway neoplasm. Placement of the stents was performed under rigid bronchoscopic guidance. We had no complications from our technique of stenting. There has been no evidence of restenosis or occlusion within the stented segment of airway. The complementary use of expandable metal and Silastic endobronchial stents provided symptomatic and functional improvement in our patients during follow-up ranging from 5 to 24 months.

Adult↗
PubMed1992

Self-expanding metal stent for tracheobronchial strictures.

To determine the role of expandable metal stent (Wallstent) in treating tracheobronchial strictures, 12 patients with recurrent symptoms of airway obstruction due to either benign or malignant strictures were studied. The seven benign strictures were anastomotic stricture following sleeve resection (2) and single lung transplant (1), tracheal amyloidosis (1), idiopathic chondritis (2), and post-tracheostomy stricture (1). The five malignant strictures were due to recurrent adenoid cystic carcinoma of trachea (1), large-cell carcinoma of lung (1), recurrent laryngeal squamous carcinoma (1), squamous carcinoma of the trachea (1), and malignant melanoma (1). The placement of stents was performed under rigid bronchoscopic guidance with no complications. All patients with benign strictures derived subjective and functional improvement with stenting. No evidence of restenosis within the stented segment in six of the seven benign strictures was found within up to 24 months. Repeated diathermy resection was required in the patient with recurrent amyloidosis through the distal end of the stent. Among the malignant strictures, symptomatic relief was achieved in four of the five patients. One metal stent migrated proximally and was replaced by a Montgomery T tube. One patient with relief of stridor died at 4 months due to carcinomatosis. Tumour ingrowth through the metal stent remains problematic in two patients. However, the incidence of palliative interventions required has markedly reduced after stenting.

Adult↗
PubMed1992

The development of a light curing prosthesis for chest wall replacement.

In conjunction with colleagues in the chemical industry, we have developed and evaluated a new plastic prosthesis which we hope will supplant presently used materials for chest wall replacement. We have modified the basic chemical of a reactive resin routinely used in orthopaedic and dental work by the inclusion of a polypropylene mesh. The resultant material is thin enough to cut with scissors and yet supple enough to shape to fit the defects. It is hardened by exposure to UV light and has a practical cure time when exposed to normal light in the operating theatre. When set it is strong and rigid. The mechanical properties have been studied with the Flexural 3-point bend test and compared with the best of the presently available prostheses. The inert nature of the material was studied in a subcutaneous implant in 29 rats over 3 months. Histology has shown a lack of reactivity. The stability in vivo was studied using the material to replace portions of the chest wall in rabbits for up to 6 months. Subsequent histology and in-vitro testing have proved satisfactory. The ability of this material to withstand the dynamic stresses of the chest wall have been studied by its implantation into the chest wall of 3 minipigs for 6 months. The material looks promising and has proved more "user friendly" than existing prostheses for flat bone replacement. We hope to refine its production to allow its use in humans.

Animals↗
PubMed1992

Aorto-cutaneous fistula: a rare complication of aortic surgery.

Two cases of false aneurysm of the ascending aorta which presented with discharge of arterial blood from a sternal wound are discussed. The first presented 8 years after aortic valve surgery and was diagnosed by contrast enhanced computerised tomography of the thorax. The second presented 6 months following repair of an aortic dissection and the diagnosis was confirmed by thoracic magnetic resonance imaging. The diagnosis and surgical management of these cases are reviewed.

Aged↗
PubMed1992

Lung transplantation for cystic fibrosis.

Significant progress has been made since the first successful human heart-lung transplantation (HLT) for pulmonary vascular disease performed in 1981. The refinement of surgical techniques, use of cyclosporin as the main immunosuppressant, technique of distant organ procurement to expand the donor organ pool, and improved diagnosis and management of pulmonary infection and rejection have all contributed to this accomplishment. This has inevitably coincided with the extension of this procedure to other groups of patients with end stage heart and lung disease. Initially, HLT was offered to patients with cardiac disease associated with pulmonary hypertension. Because of the success, consideration was given to transplantation for parenchymal pulmonary diseases, initially pulmonary fibrosis and emphysema, and then suppurative lung disease such as in cystic fibrosis (CF). However, the application of HLT to patients with CF lagged behind because of concern related to the risk of sepsis, the systemic nature of the disease, malnourishment, and fear of recurrence of the epithelial CF defect in the transplanted lungs.

Adolescent↗
PubMed1992

Open lung biopsy: a safe, reliable and accurate method for diagnosis in diffuse lung disease.

The ideal method for obtaining lung tissue for diagnosis should provide high diagnostic yield with low morbidity and mortality. We reviewed all 432 patients (mean age 55 years) who underwent an open lung biopsy at this hospital over a 10-year period. Twenty-four patients (5.5%) were immunocompromised. One hundred and twenty-five patients were on steroid therapy at the time of operation. Open lung biopsy provided a firm diagnosis in 410 cases overall (94.9%) and in 20 out of 24 patients in the immunocompromised group (83.3%). The commonest diagnosis was cryptogenic fibrosing alveolitis (173 patients). Twenty-two patients (5.1%) suffered complications following the procedure: wound infection 11 patients, pneumothorax 9 patients and haemothorax 1 patient. Thirteen patients (3.0%) died following open lung biopsy, but in only 1 patient was the death attributable to the procedure itself. We conclude that open lung biopsy is an accurate and safe method for establishing a diagnosis in diffuse lung disease with a high yield and minimal risk.

Adolescent↗
PubMed1990

Incidence, causes and mechanism of hypercalcaemia in a hospital population in Hong Kong.

To determine the incidence and causes of hypercalcaemia in a hospital population in Hong Kong, all 29,107 samples received in the laboratory in one year were analysed for plasma calcium and albumin, and samples with a plasma calcium concentration adjusted for albumin greater than 2.55 mmol/l were investigated. Plasma calcium greater than 2.55 mmol/l was found in 462 patients. Repeat samples were received from 302 of these and hypercalcaemia was confirmed in 183. The main causes of hypercalcaemia were malignancy (72.1 per cent), tuberculosis (6.0 per cent), and primary hyperparathyroidism (5.5 per cent). In the malignant hypercalcaemia group, carcinoma of lung was the most common (31.8 per cent) and carcinoma of breast was uncommon (3.0 per cent). Secondary deposits in bone were detected in 35 of the 122 solid tumours. In order to identify the mechanism of hypercalcaemia the contributions of renal tubular reabsorption and increased bone resorption to the plasma calcium concentration were calculated. Increased tubular reabsorption was the main contributor to hypercalcaemia in primary hyperparathyroidism and carcinoma of liver (none of whom had bony metastases) and it contributed significantly to hypercalcaemia in carcinoma of lung without bony metastases and carcinoma of oesophagus. We conclude that in Hong Kong (a) primary hyperparathyroidism is uncommon, (b) tuberculosis is an important cause and (c) humoral factors may be responsible for a relatively high proportion of cases of malignant hypercalcaemia.

Aged↗