Respiratory Disease in the Immunosuppressed Host [antikvár]

Preface The definition of immunosuppression has changed dramatically in recent years with recognition of the complex and broad spectrum of altered immuné states. Immunosuppression is not easily defined as a relative or absolute defect in antigén processing or effector cell (B lymphocyte, T lymphocyte, macrophage, neutrophil) function. Immunosuppression due to disease may be multifactorial and may be exacerbated by immunosuppression due to cytotoxic, hormonal, anti-inflammatory, radiation, or immunomodulatory therapy. Host defenses may be compromised by local insults or abnormalities, as well as by systemic illness and by therapy for illness. The definition of immunosuppression has alsó changed with the recognition of new diseases such as those associated with infection with the humán immunodeficiency virus and related retroviruses. In many forms of immunosuppression, patients present with pulmonary disease. The identification of a specific process with a defined etiology and a defined therapy and prognosis is the goal of physicians caring for these patients. However, because of concurrent problems such as thrombocytopenia or respiratory failure, it is frequently difficult to establish a precise diagnosis, and attempts to do so may inflict additional patient morbidity. The diagnostic task is alsó complicated by the need to diagnose urgently and treat pulmonary complications on the assumption that early effective treatment improves prognosis. The types of pulmonary disease that affect an immunosuppressed patient depend on a variety of factors, including the patient's illness, associated medical problems, the immunologic lesion, and the patient's personal and geographic environment. Perhaps no other patient population poses such medical challenge in terms of the variety of pathologic processes that might occur and the difficulties associated with making a diagnosis. The demands on the physician caring for immunosuppressed patients are considerable. Not only must physicians understand the disease processes to which such patients are susceptible, they must alsó have a reasonable knowledge of typical and atypical presentations of disease, and a working knowledge of the sensitivity, specificity, and potential morbidity of various diagnostic procedures. The physician attending immunosuppressed patients frequently must distinguish among complications of disease, complications of therapy, and intercurrent illnesses, which may be related to disease or therapy. With the ever-expanding armamentarium of diagnostic tests available, the physician must choose the test that is most likely to yield a diagnosis at the lowest cost in morbidity. And because disease processes may progress rapidly to respiratory failure and death in immunosuppressed patients, physicians must not only act expeditiously to achieve a diagnosis and institute therapy, they must alsó plan ahead for additional diagnostic and therapeutic maneuvers, should the initial diagnostic step be unhelpful or the initial therapy prove unsuccessful. Finally, knowledge of the varieties of infectious diseases occurring in specific patient populations as reported in the literature is important; however, such processes may vary not only with time in one institution but alsó from institution to institution. Thus, the incidence of Pneumocystis carinii pneumonia may vary dramatically between institutions and within one institution over time, owing to changes in chemotherapy, prophylaxis, or other variables. Central to the care of immunosuppressed patients are reasonable algorithms for the evaluation of pulmonary disease in specific patient populations and a rational approach to empirical therapy, if such is needed. In somé patient populations, perhaps 50% of pulmonary processes are not infectious. Thus, the physician must bear in mind the morbidity of empirical therapy as well as the morbidity of diagnostic procedures. This book is written in five parts. Part I presents a generál perspective on pulmonary host defenses and on the effects of somé therapies on those defenses. Part II examines the utility of different diagnostic procedures in the immunosuppressed