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Biomedical subjects

K H Fan

Publications and source records attributed to K H Fan.

8 recordsLinked to original sources
PubMed2000

A comparative study of tracheal intubation using an intubating laryngeal mask (Fastrach) alone or together with a lightwand (Trachlight).

STUDY OBJECTIVE: To determine if the Trachlight lightwand can facilitate Fastrach intubation by guiding the tip of the endotracheal tube into the trachea. DESIGN: Open-label, prospective, randomized, comparative study. SETTING: General operating suites of a tertiary teaching hospital. PATIENTS: 172 elective surgical patients requiring general anesthesia with endotracheal intubation. INTERVENTIONS: With general anesthesia, the Fastrach, which is a new intubating laryngeal mask airway, was inserted into the oropharynx. Ventilation was ensured before the insertion of an endotracheal tube via the Fastrach. Tracheal intubation was then performed randomly (coin toss) using either the endotracheal tube alone (Fastrach group), or endotracheal tube with the Trachlight, a lightwand (Fastrach/Trachlight group). The time to place the Fastrach and endotracheal tube, to remove the Fastrach, and the total time to intubate were recorded. The number of attempts, failures, trauma, sore throats, and hemodynamic changes were also recorded. Data were analyzed using unpaired t-test, ANOVA with repeated measures, or Chi-squares contingency table where appropriate. MEASUREMENTS AND MAIN RESULTS: Although there were no differences in the times to place the Fastrach, and endotracheal tube, the hemodynamic changes, and postoperative complications, there were significantly more attempts and failures in the Fastrach group compared to the Fastrach/Trachlight group. There were no differences in the incidence of sore throat and trauma in between the groups. CONCLUSIONS: Although tracheal intubation is effective using a Fastrach alone (76% success rate), it is more effective when the Fastrach is used in conjunction with the Trachlight (95%). These results suggest that the lightwand is a useful adjunct for Fastrach intubation. However, the role of Fastrach intubation together with the Trachlight in the management of patients with a potential difficult airway remains to be determined.

Anesthesia, General↗
PubMed2000

Assessing the implant/bone interface by using natural frequency analysis.

OBJECTIVE: A number of techniques have been proposed for detecting the stability of dental implants. However, the clinical applicability of those methods is still limited. The purpose of this study was to evaluate a new innovative, noninvasive, minimum-contact method for the stability assessment of dental implants. STUDY DESIGN: Natural frequency is a physical property of a structure, which is strongly related to its boundary conditions. In this study, a modal testing technique was carried out to measure the natural frequency of dental implants. The implants were fixed by a metal clamp stand and were excited to vibrate by an impulse hammer. A noncontact piezoelectric microphone then acoustically acquired the vibration responses of the implants. Natural frequencies of the tested implants were recorded under various clamping forces and clamping levels. RESULTS: Natural frequencies of the tested implants were concentrated from 8 to 19 kHz under different boundary conditions. On the other hand, the natural frequency values decreased when boundary levels and boundary force were reduced. Linear relationships (P <.005) were found between response frequencies and the degree of implant stability. CONCLUSIONS: Our results show that the boundary status of an implant can be monitored by detecting its natural frequency. A noncontact transducer used in this study can also serve as a useful tool for future clinical investigations.

Dental Implants↗
PubMed1996

Inherited and acquired risk factors in colonic neoplasia and modulation by chemopreventive interventions.

The progressively abnormal development of epithelial cells prior to tumor development leads to widely differing chemopreventive approaches. The diversity of these approaches has resulted in different assays to measure the activities of the agents. To apply these assays to preclinical studies, we have developed rodent models in which different stages of evolution of colonic neoplasia are expressed. In one model mice carrying a truncated Apc allele with a nonsense mutation in exon 15 have been generated by gene targeting and embryonic stem cell technology (Apc 1638 mice). These mice develop multiple gastrointestinal lesions including adenomas and carcinomas, focal areas of high grade dysplasia (FAD) and polypoid hyperplasias with FADS. The incidence of inherited colonic neoplasms has now been modulated by a chemopreventive regimen. Colonic lesions significantly increased in Apc 1638 mice on a Western-style diet, compared to Apc 1638 mice on AIN-76A diet which has lower fat content and higher calcium and vitamin D. These studies have also been carried out in normal mice, and have demonstrated without any chemical carcinogen that a Western-style diet induced colonic tumorigenesis. Modulation of cell proliferation has also been induced by Western-style diets in other organs including mammary gland, pancreas and prostate. These findings are leading to the development of new preclinical models for evaluating the efficacy of many classes of chemopreventive agents.

Animals↗
PubMed1988

[Digital noninvasive microwave thermography in the diagnosis of breast disease].

Thermography is a noninvasive technic of examination. Liquid-Crystal Thermography and Infrared Thermography have provided great help in the general survey of breast diseases during the past twenty years but not without some limitations. Recently, by applying the microwave technic clinically, progress has been made to measure minute temperature changes in the deeper tissues. Differential diagnosis of breast disease is possible by statistical calculating the temperature difference of the two breasts. A prospective study was done in 96 women who had both X ray mammography and digital noninvasive microwave thermography. 70/96 were proved by pathology. In this group of patients, the accuracy rate was 70.00% for digital microwave thermography, 81.82% for X ray mammography and 95.50% for the two combined. The false positive rates and false negative rates, advantages, disadvantages and the for general survey of breast disease of the digital microwave thermography discussed.

Adenofibroma↗
PubMed1987

[X-ray features of primary non-squamous cell carcinoma and other malignant neoplasms in the trachea and main bronchi--analysis of 23 cases].

X-ray features of 23 cases (25 foci) of non-squamous cell carcinoma and other malignant neoplasms in the trachea and main bronchi were reviewed. They were 15 (17 foci) adenoid cystic carcinomas, 3 carcinoids, 2 mucoepidermoid carcinomas, 1 well-differentiated adenocarcinoma, leiomyosarcoma and extramedullary plasmocytoma each. The symptoms were non-specific leading to a delayed diagnosis more than one year in 52% of cases. The X-ray findings were classified into 3 types: intraluminal polypoid (11 tumors), sessile mass without and with extraluminal invasion (3 and 11 tumors). These tumors were prone to extraluminal invasion and can be demonstrated by X-ray. The air lumen involved appeared as localized expansion in 3 adenoid cystic carcinomas, 1 of which was proved by operation. Routine chest films were of limited value with 30% false negative chest film, 26% mediastinum mass and 30% obstructive pneumonitis/atelectasis. Lesions of posterior tracheal wall and carina were better revealed by lateral tomography. Of the 10 cases with lateral tomography, images were superior to those of AP tomography in 5. Three cases had CT scan, by which intra-tracheal/bronchial lesions, invasions of mediastinum and regional lymph nodes were shown. CT scan is more accurate compared with the other imaging modalities in visualizing these lesions and more helpful in selecting treatment.

Adolescent↗
PubMed1986

[Malignant fibrous histiocytoma (MFH) of the maxilla--an analysis of 7 cases].

Malignant fibrous histiocytoma is a rare tumor of the soft tissue or bone, especially if located in the head and neck. Up to the present, only 7 cases have been reported (6 in the mandible and only one in the maxilla). From Mar. 1958 to Mar. 1985, 7 patients with maxillary MFH, proved by pathology, were treated in our hospital. The X-ray manifestations were studied and analysed. The main X-ray characteristics are as follows: A large soft tissue mass in the maxilla, extending into the infratemporal fossa, pterygopalatina fossa, orbit, ethmoid sinuses, nasal cavity and cheek. Marked and extensive destruction of the maxilla with some amorphous reactive ossification. The bone appears like melting ice or ground glass. The value of computerized tomography in differential diagnosis and clinical staging of the maxillary malignant fibrous histiocytoma are discussed.

Adult↗
PubMed1984

High dose rate radiosensitization: a clinical pilot study of 27 cancer patients.

In laboratory experiments, it was reported by some authors that radiation response increases with the dose rate, although other workers have reported that this relationship does not exist. Up to the present, this problem has remained controversial. The present clinical pilot study was designed with the aim of comparing the effect of high and low dose rates. The study was carried out on 27 patients who suffered from various types of malignancy. Twelve patients with advanced but relatively comparable bilateral metastases in the neck region, and 15 patients with multiple pulmonary metastatic foci were studied. Radiation was given at a high dose rate (1112 rad/min) when irradiating one side of the neck or one of the metastatic lesions in the lung, while radiation was given at a low dose rate (400 rad/min) on the opposite side of the neck or a separate lesion in the lung. All other aspects of radiation, however, were identical for all lesions. The total dose varied from 4000-7000 rad/4-7 wk. Five fractions per week and a daily dose of 200-300 rad was given. It was observed that the high dose rate gave rise to a higher radiosensitivity than the low dose rate. Tumor regression rates were calculated by measuring the dimensions of the lesions. The tumor regression rate in the high dose rate group was universally higher than that in the low dose rate group. The radiation response in the high dose rate group was about 5.2-37.6%, averaging 18%, higher than that in the low dose rate group. In conclusion, a high dose rate of radiation elicits a higher radiosensitivity, and hence, a possible higher cancericidal effect.

Adolescent↗