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Biomedical subjects

J D Zibrak

Publications and source records attributed to J D Zibrak.

10 recordsLinked to original sources

Indications for pulmonary function testing.

STUDY OBJECTIVE: To critically assess original studies evaluating the role of preoperative pulmonary function testing in predicting postoperative outcomes. DESIGN: MEDLINE search of English-language articles from 1966 to 1987 using the following medical subjects headings respiratory function tests, lung, lung diseases, and preoperative care. MEASUREMENTS AND MAIN RESULTS: Relevant studies were subdivided by operative site. We included only studies for which we could determine pre- and post-test probabilities of morbidity, mortality, sensitivity, and specificity. Preoperative pulmonary function testing was found to have measureable benefit in predicting outcome in lung resection candidates. In selected patients, split perfusion lung scanning and pulmonary exercise testing appeared to be useful. Confirmation of these reports is necessary before these preoperative tests can be routinely recommended. In studies of upper abdominal surgery, spirometry and arterial blood gas analysis did not consistently have measureable benefit in identifying patients at increased risk for postoperative pneumonia, prolonged hospitalization, and death. Studies of preoperative testing for other patients, including those having coronary artery bypass grafting, lacked adequate data for meaningful analysis. CONCLUSIONS: Preoperative pulmonary function testing helps clinicians to make decisions on management of lung resection candidates. Although many studies of patients before abdominal surgery have focused on the utility of preoperative pulmonary function testing, methodologic difficulties undermine the validity of their conclusions. The impact of testing on care of other preoperative patients is even less clear because of poor study design and insufficient data. Therefore, further investigation is necessary before a consensus can be reached on the role of preoperative pulmonary function testing in evaluating patients before all surgical procedures except lung resection.

Abdomen

Myasthenia gravis presenting as isolated respiratory failure.

A patient with myasthenia gravis presenting as respiratory failure was unusual in his lack of peripheral neuromuscular involvement, negative results on many commonly used diagnostic tests, and lack of response to firstline therapeutic measures. Review of the pertinent literature revealed no previously described presentation of myasthenia gravis in this manner.

Humans

Evaluation of intermittent long-term negative-pressure ventilation in patients with severe chronic obstructive pulmonary disease.

We tested the hypothesis that intermittent ventilatory assistance in patients with severe chronic obstructive pulmonary disease (COPD) improves pulmonary function and exercise capacity. Twenty stable patients with severe COPD were recruited from outpatient pulmonary clinics and were randomized to use a poncho wrap, negative-pressure ventilator or to receive standard care. After 6 months, the patients receiving standard care were switched over to the ventilator and vice versa, and follow-up was continued for an additional 6 months. After 3 to 6 months of ventilator use, we observed no clinically significant improvements in FEV1, FVC, blood gas determinations, maximal inspiratory and expiratory pressures, and exercise duration. However, 11 of our patients dropped out of the study because of an inability to tolerate the ventilator, and all but one of the nine who completed the study expressed dissatisfaction with it, using it for less time (4.1 h/day) than we recommended. Musculoskeletal pain and inconvenience were the most frequently voiced complaints. Because we did not document that ventilator use actually rested the respiratory muscles in our patients and because duration of ventilator use may have been too brief, we cannot conclude that intermittent rest of respiratory muscles in patients with severe COPD fails to bring about improvement. On the other hand, our results demonstrate that the poncho wrap ventilator is poorly tolerated by patients with severe COPD in a typical outpatient setting. We suggest that future trials seek to utilize better tolerated ventilatory assist devices.

Clinical Trials as Topic

Abnormal airway function in individuals with the acquired immunodeficiency syndrome.

Pulmonary function test results of individuals with the acquired immunodeficiency syndrome (AIDS) were analyzed to determine the prevalence of abnormally low forced expiratory flow rates and bronchial hyperreactivity. Of 99 individuals with AIDS, a total of 44 (44 percent) had either low forced expiratory flow rates or a significant response to inhaled bronchodilator. Thirty-one (31 percent) individuals exhibited significant improvement in airflow rates after bronchodilator inhalation, while 33 (33 percent) had low flow rates. Twenty (20 percent) individuals had both low flow rates and a significant response to bronchodilator. In 83 percent of symptomatic individuals treated with bronchodilators there was clinical improvement. Thus, we conclude that abnormally low forced expiratory flow rate with or without bronchial hyperreactivity is a common and treatable complication of AIDS.

Acquired Immunodeficiency Syndrome

Cytoplasmic enzyme patterns in isolated hamster pulmonary alveolar type II cells.

Three cytoplasmic enzyme patterns were studied in pulmonary alveolar type II cells isolated from normal adult hamster lung: lactate dehydrogenase (total and isoenzymes), peroxidase, and beta-N-acetylglucosaminidase. Enzyme patterns of freshly-isolated type II cells were found to be different from those of freshly-isolated pulmonary hamster fibroblasts. After both types of cells had been cultured for seven days, no difference in cytoplasmic enzyme patterns remained. Lactate dehydrogenase isoenzyme patterns for type II cells were different from those obtained from polymorphonuclear leukocytes and alveolar macrophages. These data may be useful in detecting sources of lung injury by assessment of enzyme patterns in bronchoalveolar lavage fluid.

Acetylglucosaminidase

Pulmonary infiltrates and hypoxemia in patients with the acquired immunodeficiency syndrome re-exposed to trimethoprim-sulfamethoxazole.

Fever, hypotension, pulmonary infiltrates, and hypoxemia developed upon re-exposure to trimethoprim-sulfamethoxazole in 2 patients with the Acquired Immunodeficiency Syndrome. This reaction can mimic sepsis or the clinical worsening of underlying pulmonary opportunistic infection. The literature concerning adverse pulmonary effects of trimethoprim-sulfamethoxazole is reviewed.

Acquired Immunodeficiency Syndrome

Bronchoscopic and radiologic features of Kaposi's sarcoma involving the respiratory system.

In a group of 61 patients admitted to New England Deaconess Hospital, Boston, with a diagnosis of acquired immune deficiency syndrome (AIDS), 25 were found to have Kaposi's sarcoma involving the skin and mucous membranes. Of these 25 patients, eight had lesions involving the respiratory system. Radiographically, patients with Kaposi's sarcoma had hilar and mediastinal adenopathy with perihilar parenchymal infiltration which progressed to diffuse bilateral infiltrates over a period of months. This pattern and the tempo of its evolution were distinctly different from the diffuse infiltrates seen in patients with Pneumocystis carinii pneumonia. Bronchoscopy was performed in seven of the eight patients, revealing characteristic lesions of Kaposi's sarcoma in the airways. We propose that parenchymal pulmonary Kaposi's sarcoma can be strongly suspected in a patient with AIDS who has the following features: a characteristic radiologic pattern; endobronchial Kaposi's sarcoma at bronchoscopy; and no evidence of opportunistic infection. In this subset of patients, further diagnostic intervention such as open lung biopsy, a procedure with potential morbidity in these ill individuals, may be unnecessary.

Acquired Immunodeficiency Syndrome

Isolation and characterization of a rat lung fraction enriched in alveolar wall basement membranes.

Separation of lung alveolar basement membranes from interstitial connective tissue protein has proved difficult, and a pure preparation of alveolar wall basement membranes (AWBM) is not available. We have modified a technique employing the detergent Triton X-100 for isolating AWBM from rat lungs by adding a step utilizing human skin collagenase (HSC), a highly purified enzyme obtained from skin fibroblasts that specifically cleaves non-basement membrane collagens. Triton extraction of both lungs yields 15-20 mg of basement membrane-enriched material referred to as crude fraction (CF). Ultrastructural studies show that CF includes both epithelial and endothelial basement membranes that appear similar to their in vivo counterparts and contain heparan sulfate proteoglycans. Extraction of type IV collagen is documented by the appearance of highly glycosylated hydroxylysine. This CF contains minimal amounts of contaminating elastin but significant amounts of interstitial collagens. CF was further purified for biochemical studies by incubation with HSC. HSC solubilized 20% of CF hydroxyproline resulting in a final fraction highly enriched in AWBM. Lung minces incubated in tritiated lysine produced a CF extract rich in newly formed type IV collagen, showing that lung tissue synthesizes AWBM collagen in vitro.

Animals