Biomedical subjects
Publications and source records attributed to A Chausow.
A patient with palatal myoclonus and involvement of respiratory muscles is described. Partial characterization of the mechanism of ventilatory dysfunction was achieved using noninvasive tests. Ventilatory dysfunction in this disorder can be manifested in different patterns depending on which respiratory muscles are involved predominantly.
Physiological studies performed 1 week after initiation of thyroid replacement showed persistence of significant respiratory muscle weakness in a patient presenting with hypothyroidism and hypercapnia. Repeat studies 12 months later demonstrated return of respiratory muscle strength to normal. Earlier reports on respiratory failure in hypothyroidism had postulated a critical role for respiratory muscle weakness in the genesis of hypercapnia. Since hypercapnia was rapidly reversed despite the persistence of severe respiratory muscle weakness, this explanation may not be always correct. It appears than in our patient thyroid replacement had its primary effect on the respiratory control system.
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The tussive and bronchoconstrictive effects of hyperpnea with cold air (HCA) are described in 3 patients with exercise-induced cough, 7 volunteers with exercise-induced cough, and 7 asymptomatic volunteers. Cough associated with HCA exceeded baseline cough in each of the patients and volunteers with exercise-induced cough and in all but one of the asymptomatic volunteers. The time course of cough was similar in each group. Maximal cough frequency occurred during the first 5 min after HCA and persisted to a much lesser degree during the ensuing 26 min. The time course of bronchoconstriction was similar to that of cough, with maximal decrements in specific airway conductance measured 5 min after HCA. Pretreatment with albuterol blocked HCA-induced bronchoconstriction but had no effect on HCA-induced cough. No subject in any of the 3 groups was hyperreactive to methacholine aerosols. In subjects who are nonhyperreactive to methacholine aerosols, HCA has a characteristic, reproducible, and predictable tussive effect. Thus, HCA may be a useful tool for investigating the mechanism of cough and for evaluation of antitussive drugs.
We studied 59 patients presumed to have pulmonary tuberculosis to determine whether gallium-67 citrate scintigraphy could improve diagnostic accuracy and help clinical decision making for empiric treatment pending culture results. The sensitivity of 67Ga scintigraphy was 95% and the specificity 27%. Our positive predictive value of 69% does not contribute substantially to increase the prior probability of diagnosis in settings similar to ours. The existence of a false negative rate essentially precludes the use of the scan to rule out active disease. The use of the scan for clinical decisions in pulmonary tuberculosis is not recommended.
Pulmonary function was tested before and after the administration of a commercial preparation of factor VIII concentrate in 20 patients with hemophilia A. The material was infused through the filter provided by the manufacturer, which is supposed to remove particles larger than 170 mu. Baseline information showed that patients who smoke had a lower pulmonary diffusing capacity for carbon monoxide than nonsmokers (22.9 +/- 4.2 ml/minute/mm Hg, p less than 0.01). The administration of factor VIII was not associated with clinical abnormalities. There was a small reduction in carbon monoxide diffusing capacity (27 +/- 5.8 to 26.2 +/- 5.9 ml/minute/mm Hg, p = 0.03), which was no longer significant after carbon monoxide diffusing capacity was corrected for lung volume (5.66 +/- 1.32 to 5.54 +/- 1.34, p greater than 0.06). This study does not support the need for 40 mu filtration of factor VIII concentrate.
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