Attilio D. Renzetti

Interactions between Viruses and Bacteria in Patients with Chronic Bronchitis

Abstract The possibility that viral infections of the respiratory tract might predispose to bacterial colonization or infection was studied in 120 patients with chronic obstructive pulmonary disease and 30 control subjects; these individuals were observed for seven years. The ratio of the number of observed to the number of expected associations between viruses and bacteria was 2.43 (P = 0.037) for the pair influenza virus and Streptococcus pneumoniae and was 2.06 (P = 0.056) for influenza virus and Haemophilus influenzae. Consistently positive, but not significant, associations were detected between rhinovirus and herpes simplex virus infections and isolations of S. pneumoniae and H. influenzae. In contrast, isolations of the nonpathogenic Haemophilus parainfluenzae could not be related to prior viral infections. Significant rises in titer of antibody to H. iniluenzae were detected on 76 occasions, and 20 (26%) of these antibody rises were associated with viral or mycoplasmal infections during the preceding 120 days. The expected number of such associations was 8.34 (ratio of number observed to number expected, 2.40; P = 0.08). These results suggest that viral infections of the respiratory tract in patients with chronic obstructive pulmonary disease are associated with increased colonization by potentially pathogenic bacteria and may also predispose to infection with H. injluenxae.

Effect of Viral Infections on Pulmonary Function in Patients with Chronic Obstructive Pulmonary Diseases

Abstract 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 I-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.

Informative Value of Simple Multibreath Nitrogen Washout Measurements for Clinical and Research Purposes

Some simple multibreath nitrogen washout indexes quantifying inspired gas distribution and ventilatory efficiency were obtained in a group of patients with mild to advanced chronic obstructive pulmonary disease (COPD) and studied in their relationships with routine pulmonary function tests. The indexes (lung clearance index (LCI), mixing ratio (MR) and data obtained by graphic analysis of the washout curve) were correlated with spirometric, pulmonary mechanics and arterial blood gas measurements, but only 8-38% of the interindividual variation in these indexes was explained by the above routine tests. An additional 5-13% of the variation was explained by the washout tidal volume (VT); this finding may reflect changes in gas distribution with VT and/or the influence of the dead space on ventilatory efficiency. Our data indicate that, in patients with COPD, nitrogen washout indexes tend to change in parallel with routine pulmonary function tests, reflecting the severity of the disease; these indexes also contain specific information (in addition to that provided by routine physiologic tests), presumably related to the distribution and efficiency of ventilation. Nitrogen washout measurements may thus represent a helpful adjunct to routine pulmonary function testing; LCI and MR appear to be particularly convenient for practical purposes because of their simplicity, and an informative content comparable with that of more complex indexes.

Pulmonary Resistance and Dynamic Compliance as Functions of Respiratory Frequency

The behavior of pulmonary resistance (RL) and that of dynamic compliance (Cdyn) as functions of respiratory frequency (f) were compared in normal subjects and in patients with chronic obstructive pulmonary disease (COPD). Although both RL and Cdyn varied with f in most COPD patients and in some normal subjects, Cdyn appeared to be more sensitive than RL to variations of frequency; no significant changes in RL could be demonstrated in subjects in whom Cdyn was frequency dependent. The degree of frequency dependence of Cdyn was correlated with the severity of respiratory impairment (as quantified by conventional pulmonary function tests); in contrast, RL was not detectably frequency dependent in some subjects with advanced COPD. Compared with Cdyn, RL was more commonly nonlinearly related to respiratory frequency, often increasing at high breathing rates. Our results indicate that changes in RL with frequency are less predictable and more difficult to detect than the corresponding changes in Cdyn.

Chronic eosinophilic pneumonia: A report of four cases and a review of the literature

Abstract: The clinical and radiological findings of four patients with chronic eosinophilic pneumonia are presented. This brings the total number of cases in the English literature to 27. A comparison of all 27 patients is given. The syndrome can readily be distinguished from other eosinophilic pneumonias. After appropriate evaluation, a therapeutic trial can often be initiated with corticosteroids without the necessity for histologic confirmation of the diagnosis.