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Biomedical subjects

A D Renzetti

Publications and source records attributed to A D Renzetti.

At least 37 records · Page 2Linked to original sources
PubMed1981

Measurement of oxygen consumption and carbon dioxide production rates by a tracer-bolus method.

A new method for measuring oxygen consumption and carbon dioxide production is described. The method is based on the injection of a helium bolus into the inspired gas for repeated breaths; the helium can be delivered through the mouth or through a nostril (the injection system being controlled by the integrated flow signal or by the signal of a thermistor, respectively). Compared with the conventional gas-collection technique, the tracer-bolus method allows more rapid and frequent measurements. The method does not necessarily require an airtight respiratory circuit, so that it can be conveniently applied in less cooperative subjects, including children. The results of validation studies based on a comparison with the standard gas-collection technique are presented; these results indicate that the measurements by the tracer-bolus method are accurate in normal subjects. In patients with obstructive lung disease, the determinations are associated with a systematic error, which is expected, the tracer-bolus method being based on a single-compartment, uniformly ventilated and perfused lung model; the error is, however, predictable from the degree of functional impairment and can be corrected using equations based on routine pulmonary function tests.

Adult↗
PubMed1981

Respiratory disease in Utah coal miners.

Two hundred forty-two Utah underground coal miners volunteered to participate in a respiratory disease study. They were an older group (mean, 56 years of age) and had spent a mean of 29 years in the coal-mining industry. The prevalence of chronic bronchitis was 57%, and that of coal worker's pneumoconiosis, 25%; only one worker had progressive massive fibrosis. Significant impairment of pulmonary function was found among those with a history of cigarette smoking. Chronic bronchitis or coal worker's penumoconiosis among nonsmokers did not impair pulmonary function. There was a significant association among the nonsmokers between increasing exposure to coal dust and coal worker's pneumoconiosis, but not for changes in pulmonary function. Coal mine dust had a significant influence in causing the symptom complex of chronic cough and sputum production, and coal worker's pneumoconiosis.

Bronchitis↗
PubMed1981

Bronchodilator effects of nebulized fenoterol: a comparison with isoproterenol.

In an attempt to find the optimal single therapeutic dose of fenoterol inhalant solution administered by compressor-powered nebulization, bronchodilator and side effects of five different doses of fenoterol (0.5, 1.0, 1.5, 2.0, and 2.5 mg) and of placebo were compared with those of the recommended therapeutic dose delivered from a metered dose canister in 16 patients with reversible airway obstruction. The fenoterol (except for the metered dose) and the placebo were given in a double-blind, cross-over manner. In comparison with placebo, all doses of fenoterol produced a significant increase in average values of FEV1, FEF25-75%, FVC, and SGaw and decrease in FRC for five to eight hours. There was a trend for the bronchodilator action to become greater and more prolonged with increasing doses of fenoterol. Compared with 0.4 mg given from a metered dose canister, 0.5 mg of fenoterol delivered by compressor powered nebulization was equally effective in bronchodilator potency. Dose-by-dose comparison with isoproterenol indicates that fenoterol is a more potent and longer lasting bronchodilator and has no significant effect on heart rate and blood pressures. The most common side effects were shakiness or tremor of hands which appeared to be dose-related in terms of incidence and intensity. The results of the present study suggest that 0.5 to 1.0 mg of fenoterol is a suitable single therapeutic dose when administered by compressor-powered nebulization.

Adolescent↗
PubMed1980

Effect of viral infections on pulmonary function in patients with chronic obstructive pulmonary diseases.

The effect of 100 separate viral infections of the respiratory tract on pulmonary function was evaluated prospectively over an eight-year period in 84 patients with chronic obstructive pulmonary diseases and in eight normal subjects. Some viral infections were associated with small acute declines in forced vital capacity and/or 1-sec forced expiratory volume of 25-300 ml. These declines were detectable only during the 90-day period after infection. The greatest abnormalities of pulmonary function followed infections with influenza virus, and the mean acute changes in 1-sec forced expiratory volume (-118.5 ml) were significantly greater than expected (-15.2 ml; P = 0.03). Smaller, statistically insignificant declines followed infections with parainfluenza virus, rhinovirus, adenovirus, and respiratory syncytial virus, and no changes were detectable after infections with coronavirus, herpes simplex virus, Mycoplasma pneumoniae, and Haemophilus influenzae. Long-term effects of influenza or other viral infections on the course of chronic obstructive pulmonary disease were not detected in this study population.

Acute Disease↗
PubMed1980

Association of viral and Mycoplasma pneumoniae infections with acute respiratory illness in patients with chronic obstructive pulmonary diseases.

The relative importance of respiratory virus and M. pneumoniae infections as causes of acute respiratory illnesses was studied over an 8 yr period in 150 subjects who were normal or who had varying degrees of chronic obstructive pulmonary disease (COPD). Viral or M. pneumoniae infections were associated with 186 of 1,030 (18%) illnesses studied, whereas these infections were detected in only 86 of 1,398 (6%) illness-free periods (P less than 0.01). Rhinoviruses, influenza viruses, parainfluenza viruses and coronaviruses were each significantly associated with acute respiratory illnesses. The occurrence of acute respiratory illnesses and viral infections was the same in subjects with moderate to severe COPD as it was in subjects who were normal or who had mild disease.

Acute Disease↗
PubMed1979

Variables associated with changes in spirometry in patients with obstructive lung diseases.

One hundred fifty subjects were enrolled in a long-term study of obstructive lung diseases; 84 of these were subjected to five or more spirometric studies over a period of two or more years. Stepdown regression analysis was performed to determine the association between many different variables and the annual rates of change in the forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). The following associations were noted to be significant (p less than 0.03); more favorable rates of change of the FVC and FEV1 were associated with a higher alpha1-antitrypsin level and older age. Less favorable changes were associated with more years of cigarette smoking, more airway reactivity and more frequent lower respiratory tract illnesses.

Age Factors↗
PubMed1976

Haemophilus influenzae and haemophilus parainfluenzae in chronic obstructive pulmonary disease.

The importance of nonencapsulated strains of Haemophilus influenzae and H. parainfluenzae in the pathogenesis of chronic obstructive pulmonary disease (C.O.P.D.) has been investigated in 150 patients observed at two-month intervals from 1968 to 1975. H. influenzae was distinguished from H. parainfluenzae by demonstrating requirements for both X and V factors. H. influenzae was isolated more often from sputum cultures from patients with severe C.O.P.D. (13.8%) than from patients with mild disease (4.4%, P less than 0.01). In contrast, H. parainfluenzae was isolated with equal frequency from sputums of patients with mild (40%) or severe (43%) disease. H. influenzae was present in the sputum more often during exacerbations of acute respiratory illness (15.4%) than during sympton-free periods (9.6%, P less than 0.01), while isolation rates of H. parainfluenzae did not increase during periods of illness (35% versus 39%). Antigens specific for the H. influenzae species and for the H. parainfluenzae species were used in a complement-fixation test to detect antibody rises in sera collected from the patient population. Fourfold or greater rises in titre of antibodies to H. influenzae were detected on 76 occasions in 53 patients, and 46 of these rises were associated with acute respiratory illnesses. In contrast, no antibody rises were detected with the H. parainfluenzae antigen. These observations indicate that nonencapsulated strains of H. influenzae may have pathogenic potential in patients with C.O.P.D., whilst H. parainfluenzae should be considered as normal flora.

Antibodies, Bacterial↗
PubMed1975

Flow and age dependence of airway closure and dynamic compliance.

The influence of expiratory flow rate and age on the results of measurement of closing volume (CV) of the lung have been studied by a nitrogen single-breath method in 66 asymptomatic lifetime nonsmoking normal subjects between 20 and 82 yr of age. Normal was defined as having values for spirometric measurements within a 95% tolerance interval of reported predicted normal mean values. For the CV determination, inspiratory flow rate was held constant at 0.51/s and studies were carried out at expiratory flow rates of 0.25, 0.5, 1.0, and 1.5 1/s. Our results show that CV expressed as a percentage of vital capacity (VC) and the slope of the alveolar plateau increases with increasing flow rate and age. Dynamic compliance (Cdyn) at frequencies corresponding to peak flow rates of 0.5 and 1.5 1/s was also measured and correlated well with the CV results. Frequency dependence of compliance with aging was demonstrated. Nine smokers with normal spirometric measurements and abnormal CV %VC were also studied. Since the results of Cdyn measurement differentiated only two-thirds of the smokers from the normal population, we suggest that the CV method is probably more sensitive than the Cdyn method for the detection of small airway obstruction.

Adult↗