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Biomedical subjects

M A Chang

Publications and source records attributed to M A Chang.

7 recordsLinked to original sources
PubMed1992

Pulse oximetry and peak flow as indicators of wheezing severity in children and improvement following bronchodilator treatments.

This study examined the changes from the initial peak flows and oxygen saturations (OSAT) of wheezing children at presentation to the emergency department through their treatment in the emergency department. Data was collected prospectively on 785 patients 5 to 20 years of age during an 11-month period from November 1, 1990, to September 30, 1991. Both the initial OSAT and peak flows were correlated with the number of bronchodilator treatments required in the emergency department and with the need for hospitalization. Both the initial OSAT and the peak flows had a limited ability to predict the need for hospitalization. Oxygen saturation appears to be a valid measure of wheezing severity and is more easily obtained in children of all ages. Following bronchodilator treatment, peak flow results in a larger quantitative improvement than OSAT; however, this difference does not appear to have any significant advantage. Aerosolized albuterol and subcutaneous epinephrine resulted in a similar degree of improvement as measured by peak flow and by oxygen saturation, with clinically similar changes in heart rate.

Adolescent↗
PubMed1990

Surgical goniosynechialysis for angle-closure glaucoma.

Fifteen patients with synechial angle-closure glaucoma uncontrolled by medical and laser therapy were treated with surgical goniosynechialysis. Five patients were treated with goniosynechialysis alone, and ten were treated with goniosynechialysis in combination with other surgical procedures. The procedure was successful, in terms of reducing synechiae, in 14 eyes (93%). The extent of angle closure was reduced from 340 degrees +/- 45 degrees (mean +/- standard deviation) preoperatively to 80 degrees +/- 70 degrees postoperatively; the mean reduction was 260 degrees +/- 95 degrees (P less than 0.0001) for the group overall and 280 degrees +/- 80 degrees (P less than 0.0007) for the subgroup treated with goniosynechialysis alone. The mean preoperative intraocular pressure (IOP) was 40 +/- 4 mmHg. The mean postoperative IOP was 14 +/- 4 mmHg. The mean reduction in IOP was 26 +/- 15 mmHg (P less than 0.0001) for the group overall and 27 +/- 18 mmHg (P less than 0.015) for the subgroup treated with goniosynechialysis alone. Glaucoma medications were reduced from a mean of 2.6 +/- 1.0 preoperatively to 1.1 +/- 1.2 postoperatively for the group overall and to 1.4 +/- 1.5 for the subgroup treated with goniosynechialysis alone. Complications consisted of two eyes with intraoperative bleeding. One of these required intraoperative conversion to surgical trabeculectomy. The other was associated with a transient postoperative IOP elevation to 40 mmHg. Surgical goniosynechialysis may be an effective means of reducing synechiae and lowering IOP, either alone or in conjunction with other surgical procedures, in patients with angle closures of less than 6 months' duration.

Adult↗
PubMed1987

The Amsler grid.

Explore the source record for details and available documents.

Humans↗
PubMed1986

Ocular abnormalities associated with cutaneous melanoma and vitiligolike leukoderma.

Several varieties of ocular pathology are associated with acquired cutaneous hypomelanosis (leukoderma; vitiligo). Our current study was undertaken to investigate the relationship between ophthalmologic disorders and a specific depigmentary phenomenon, the vitiligolike leukoderma of cutaneous melanoma. Over the past 14 years, eight patients with cutaneous melanoma and widespread areas of hypopigmentation were identified at the Pigmented Lesion Clinic of the Massachusetts General Hospital. The seven patients who underwent ophthalmologic examination had pigment-related ocular abnormalities. Among these were inflammations of the uveal tract in three patients, heterochromia in two, halo nevi of the choroid in one, and hypopigmentation and/or atrophy of the retinal pigment epithelium or choroid in four. Our findings demonstrate that ocular disease may be a component in a syndrome consisting also of cutaneous melanoma and vitiligolike leukoderma and suggest the need for complete ophthalmologic examinations in patients with melanoma and leukoderma.

Adult↗
PubMed1985

The dysplastic nevus syndrome. A pedigree with primary malignant melanomas of the choroid and skin.

Intraocular and cutaneous melanomas developed in a family with features of the dysplastic nevus syndrome. (The proband had a choroidal melanoma, his son had a cutaneous melanoma, and his grandchildren have mildly atypical melanocytic lesions clinically.) The syndrome is characterized by clinically and histologically atypical nevi, which may serve as cutaneous markers to identify persons at high risk for melanomas, both of the skin and the eye. Although it has been proposed recently that the association of intraocular melanoma with cutaneous melanoma and the dysplastic nevus syndrome may be coincidental, statistical analysis suggests that the occurrence of the two forms of melanoma in the same patient and in different members of the same family is not explained by chance alone. Therefore, until the relationship between intraocular and cutaneous melanomas is more fully elucidated, recognition of the dysplastic nevus syndrome is important, and the skin of patients suspected of having intraocular melanomas should be examined routinely for evidence of atypical melanocytic lesions.

Adolescent↗
PubMed1984

Sample size graphs for "proving the null hypothesis".

Sample size graphs are given for clinical trials designed to test whether an experimental therapy is as effective as a standard therapy. We assume a dichotomous outcome variable and a one-sided test of the hypothesis that the probability of success with standard therapy is greater than the probability of success with experimental therapy by at least some specified amount delta. Graphs are given for significance level alpha = 0.01, 0.025, 0.05; type II error beta = 0.10, 0.20; and delta = 0.10, 0.20.

Clinical Trials as Topic↗