Prevention of community-acquired pneumonia.

Preventive measures against CAP are important yet underused. Cost-effective preventive measures against CAP include influenza and pneumococcal vaccines, especially in patients over the age of 65 and other high-risk groups. There are now two antiviral agents, amantadine and rimantadine, that can be used both for prophylaxis and for therapy of influenza A virus infections to decrease the morbidity and mortality of this major predisposer of CAP. Because of fewer side effects, rimantadine should be considered the drug of choice. In selected cases (chronic bronchitis, bronchiectasis, and asplenic patients with poor vaccine response), the early use of antibiotics or prolonged use during winter months may decrease the incidence of lower respiratory infections. Use of monthly gamma globulin infusions in total or selective gamma globulin IgG-deficient patients may be beneficial in reducing the incidence of CAP in selected populations.

Use of fiberoptic bronchoscopy in the diagnosis of bronchogenic carcinoma. A study in patients with idiopathic pleural effusions.

We reviewed our experience with 115 patients with pleural effusion in whom bronchogenic carcinoma was suspected who underwent fiberoptic bronchoscopy (FOB) to identify those for whom the procedure was useful. In 6 of 12 patients with hemoptysis, 8 of 12 with a mass or infiltrate, and 8 of 18 with atelectasis with negative fluid cytology and 3 of 7 with cytology positive, FOB was useful in diagnosis. Sixty-six patients had an isolated cytology-negative effusion. Seven of 18 with massive effusion had FOB detecting cancer. Fiberoptic bronchoscopy usually was nondiagnostic in lesser-sized effusions (47 of 48). Using outcome for those with nondiagnostic FOB, we established operating characteristics for the procedure. We conclude that FOB is useful in diagnosing bronchogenic carcinoma in such patients when there is hemoptysis, accompanying lung mass or infiltrate, atelectasis, the effusion is massive, or in cytology-positive effusions without obvious primary tumor. Due to the low prevalence of bronchogenic carcinoma in patients with effusions of lesser size, we suggest that in this group FOB not be routinely performed.

Utility of fiberoptic bronchoscopy in patients with hemoptysis and a nonlocalizing chest roentgenogram.

The need for fiberoptic bronchoscopy in the patient with hemoptysis and a normal or nonlocalizing chest roentgenogram remains a subject of debate. Currently, diagnostic fiberoptic bronchoscopy is recommended as the investigative procedure of choice. To develop predictors that identify the patient in whom fiberoptic bronchoscopy is most likely to be diagnostic, we reviewed our community's experience with this population over a five-year period. We identified 196 patients with hemoptysis and a normal or nonlocalizing chest roentgenogram who underwent fiberoptic bronchoscopy. Three quarters were active or previous smokers. We examined the relationship of advancing age, sex, smoking, nonspecific roentgenographic findings and the amount, duration, and previous bouts of hemoptysis to the incidence of a diagnostic fiberoptic bronchoscopy. Twelve patients (6 percent) had bronchogenic carcinoma and 33 (17 percent) another specific cause for the hemoptysis identified by fiberoptic bronchoscopy. By univariate and discriminant analyses, we found that the three factors of age of 50 years or more, male sex, and smoking of 40 pack-years or more best predicted a diagnosis of malignancy. Bleeding in excess of 30 ml daily was associated with an increase in overall diagnostic yield. The presence of two of the three factors associated with malignancy or bleeding in excess of 30 ml daily (or both) identified 100 percent of the patients with bronchogenic carcinoma and 82 percent of all of the diagnostic fiberoptic bronchoscopic procedures. use of these criteria in selecting the patient for fiberoptic bronchoscopy could have reduced our use of the bronchoscope by 28 percent, with the remaining patients safely observed.

Effect of the rebreathing pattern on pulmonary tissue volume and capillary blood flow.

Noninvasive rebreathing measurements of pulmonary tissue volume (Vt) and pulmonary capillary blood flow (Qc) theoretically and experimentally vary with the rebreathing maneuver. To determine the cause of these variations and identify ways to minimize them, we examined the consequences of varying the volume inspired (VI), rebreathing rate (f), volume rebreathed (Vreb), and alveolar volume (VA) on the observed Vt and Qc in six normal sitting subjects. When VA was increased by progressively larger VI and Vreb, Vt increased 50 ml/l of VA. Increasing VA while keeping VI and Vreb constant did not significantly alter Vt. Diminishing Vreb while VA and VI constant caused Vt to fall 108 ml/l decrease in Vreb. Therefore the observed Vt is not simply a function of VA but increased with greater penetration of the inspired gas into the lungs. Diminishing f from 40 to 12 breaths/min caused the observed Vt to rise 27%, indicating time allowed for alveolar mixing is an important determinant of Vt. The observed Qc, in contrast, was essentially independent of the same variations in rebreathing. The above findings were similar regardless of solubility of the tracer gas (dimethyl ether instead of acetylene) or changing to the supine position. A two-compartment series lung model derived from the anatomy and rates of gas mixing in normal human pulmonary lobules produced similar changes in Vt. Thus the degree of uneven distribution between ventilation, VA, Vt, and Qc within the normal lung lobule can account for variations in the observed Vt with different ventilatory maneuvers. Slow deep breathing maneuvers tended to reduce variations in Vt. Unlike Qc, the observed value of Vt can be expected to vary substantially with pathological processes that alter pulmonary gas distribution.