The diagnosis of ventilator-associated pneumonia: a comparison of histologic, microbiologic, and clinical criteria.

STUDY OBJECTIVE: To evaluate histologic, microbiological, and clinical criteria in the recognition of ventilator-associated pneumonia (VAP) in patients who died while mechanically ventilated. METHODS: The study group consisted of 39 patients who died after a mean of 14 days of mechanical ventilation. Postmortem fiberoptic bronchoscopy (FOB) and open lung biopsy were performed with collection of specimens initiated <1 h after death. The microbiological specimens included suction catheter aspirate of tracheal secretions, FOB-guided protected specimen brush (PSB) of tracheal secretions, blindly placed PSB in a distal airway, FOB-guided PSB in a distal airway, and FOB-guided BAL fluid (BALF) in a distal airway. Qualitative bacteriologic study was performed on all specimens, and quantitative bacteriologic study was performed on all but the suction catheter aspirate of the trachea. A biopsy specimen of peripheral lung parenchyma from the same region sampled by FOB was sent for quantitative culture and histologic analysis. The BALF was analyzed for cell population and percent of neutrophils containing intracellular organisms. The clinical criteria selected for comparison with histologic and microbiological results included a temperature > or =38.5 degrees C during the 48 h prior to death, a WBC count > or =15,000/mm3 in the 48 h prior to death, presence of a bacterial or fungal pathogen on the last sputum culture, radiographic worsening in the week prior to death, and worsening gas exchange defined as a 15% decrease in the PaO2/fraction of inspired oxygen ratio in the 72 h prior to death. RESULTS: None of the quantitative cultures had a reliable positive predictive value for histologic pneumonia. None of the five clinical criteria tested showed agreement with the presence or absence of histologic pneumonia. There was a significant correlation between qualitative and quantitative microbiological results from the distal airway/FOB-guided PSB, distal airway/BALF, and quantitative culture of the lung parenchyma. Also, suction catheter aspirate of the trachea had a sensitivity of 87% in recognizing the bacterial species simultaneously present in lung parenchyma. None of the patients with histologic pneumonia had <50% neutrophils in the BALF. CONCLUSIONS: Neither the bacterial, density from the four airway quantitative cultures, nor the bacterial density from quantitative culture of lung parenchyma accurately separated the histologic pneumonia and nonpneumonia groups. No clinical criteria or combination of clinical criteria correlated with the presence or absence of histologic pneumonia. A BALF with <50% neutrophils had a 100% negative predictive value for histologic pneumonia. A BALF quantitative culture had a sensitivity of 63%, specificity of 96%, and positive predictive value of 91% in recognizing sterile lung parenchyma. Thus, BALF may have a role in excluding pneumonia/infection in the ventilated patient. Antibiotic choice for the empiric therapy of VAP can be accurately guided by the microbial population recognized through culture of a tracheal suction catheter aspirate.

A clinical profile of chronic bacterial pneumonia. Report of 115 cases.

OBJECTIVE: To review the clinical presentation, radiology, microbiology, and response to therapy of patients with chronic bacterial pneumonia. DESIGN: A retrospective analysis. SETTING: An urban tertiary care medical center. PARTICIPANTS: One hundred fifteen patients with pulmonary and/or constitutional symptoms of at least 1 month's duration with 4,000 or more colony-forming units (CFUs) of a single bacterial species identified by quantitative culture obtained via fiberoptic bronchoscopy. MEASUREMENTS: Charts were analyzed for presence or absence of any predisposing illness, symptoms at presentation, roentgenographic abnormalities, microbiologic results, findings at fiberoptic bronchoscopy, and results of therapeutic intervention. RESULTS: Sixty-five percent of patients with chronic bacterial pneumonia had a predisposing disease, 35 percent were "normal." Cough, fatigue, dyspnea, and weight loss were predominant symptoms in both groups. Bronchogenic carcinoma was newly diagnosed in 16 patients (14 percent). Haemophilus influenzae or alpha-hemolytic streptococcus was isolated in 68 percent of patients. Risk of recurrence of infection was inversely associated with duration of therapy in both groups. CONCLUSIONS: Chronic bacterial pneumonia is more common than previously recognized. It occurs in patients with and without a predisposing illness. Clinical presentation, roentgenographic appearance, and bacteriology are similar between the two groups. Cure requires prolonged antibiotic therapy.

Chronic dyspnea unexplained by history, physical examination, chest roentgenogram, and spirometry. Analysis of a seven-year experience.

The purpose of this article is to describe the spectrum and frequency of diseases presenting as unexplained dyspnea and to develop a logical diagnostic approach to such patients. Seventy-two consecutive physician-referred patients had dyspnea greater than one-month duration unexplained by the initial history, physical examination, chest roentgenogram, and spirometry. Patients underwent a standard diagnostic evaluation. A definite cause for dyspnea was recognized in 58 patients, and no answer was found in 14. Twenty-two diseases were recognized in the patient group. Dyspnea was due to pulmonary disease in 26 (36 percent) patients, cardiac disease in ten (14 percent) patients, hyperventilation in 14 (19 percent) patients, and only 3 patients had extrathoracic disease causing dyspnea. Age younger than 40 years, intermittent dyspnea, and normal alveolar-arterial oxygen pressure difference (P[A-a]O2) at rest breathing room air was strongly predictive of bronchial hyperreactivity or hyperventilation. No patient diagnosed as having disease of the lung parenchyma or vasculature had a P(A-a)O2 less than or equal to 20 mm Hg. The differential diagnosis to explain dyspnea in patients with nondirective histories, normal findings from physical examinations, normal chest roentgenograms, and normal spirograms is extensive. The patient's age and measurement of gas exchange at rest help to formulate a diagnostic approach.

Azathioprine combined with prednisone in the treatment of idiopathic pulmonary fibrosis: a prospective double-blind, randomized, placebo-controlled clinical trial.

Twenty-seven newly diagnosed patients with idiopathic pulmonary fibrosis (IPF) who were previously untreated for IPF were enrolled in a prospective, double-blind, randomized, placebo-controlled study to compare the therapeutic effect of combined prednisone/azathioprine (n = 14) with prednisone plus placebo (n = 13). Prednisone was started at 1.5 mg/kg/day (not to exceed 100 mg/day) for the first 2 wk followed by a biweekly taper to a maintenance dose of 20 mg/day. Azathioprine was administered at a daily dose of 3 mg/kg (not to exceed 200 mg/day). The patients tolerated the use of azathioprine well with few associated side effects. Changes in lung function at 1 yr, as measured by resting alveolar-arterial oxygen difference P[A-a]O2, FVC, and single breath diffusing capacity for carbon monoxide (DLCOSB), were all somewhat better in the azathioprine/prednisone group compared with the prednisone alone group, although none of these comparisons were statistically significant. Six of 14 (43%) patients randomized to prednisone plus azathioprine died during the 9-yr follow-up period, compared with 10 of 13 (77%) patients randomized to prednisone plus placebo. A Cox model survival analysis shows a nonsignificant but potentially large survival advantage for azathioprine/prednisone (hazard ratio 0.48, with 95% confidence interval increasing from 0.17 to 1.38). When adjusted for age, the survival advantage of azathioprine/prednisone becomes marginally significant (hazard ratio 0.26, with 95% confidence interval increasing from 0.08 to 0.88; p = 0.02 by large sample approximation, p = 0.05 by randomization test). We conclude that combined prednisone and azathioprine is a safe and possibly effective regimen for the treatment of IPF.(ABSTRACT TRUNCATED AT 250 WORDS)

New diagnostic approaches to the hospitalized patient with pneumonia.

The accurate diagnosis of pneumonia remains a formidable challenge in clinical medicine. The use of sputum, blood, and pleural fluid cultures provides a diagnosis in less than 50% of patients. A number of invasive techniques have recently been applied to the diagnosis of pneumonia. The methods are uniformly designed to separate upper respiratory saprophytic bacterial populations from the organisms responsible for the lower respiratory infection. Preeminent among these techniques is the use of fiberoptic bronchoscopy coupled with quantitative bacterial culture and immunofluorescence demonstration of antibody-coated bacteria. The methodology and results of this technique are described in detail in this paper. Recent clinical experience using transtracheal aspiration, percutaneous needle aspiration of the lung, and open lung biopsy are also reviewed.

Cephalosporin-induced interstitial pneumonitis.

This report describes a patient who developed dyspnea and bilateral pulmonary infiltrates following exposure to cephradine. The role of cephradine was substantiated by rechallenge.