Researchers showed that 16 weeks of treatment with the oral drug bosentan led to marked improvement in all clinical and hemodynamic parameters of the deadly disease severe pulmonary arterial hypertension (PAH). This illness is often associated with human immunodeficiency virus (HIV) infection. The new drug is an oral, dual endothelin receptor antagonist. In HIV, endothelin is believed to be produced excessively, causing vasoconstriction, cell proliferation, fibrosis, and inflammation. PAH results from chronic obstruction of small pulmonary arteries due in part to endothelial and vascular smooth muscle dysfunction and proliferation. In most cases, earlier death occurs as a direct result of PAH. The authors said that, as a result of the bosentan treatment, significant improvements were reported for parameters considered prognostic indicators of survival in the disease. These indicators included 6-minute walk distance, cardiac index, pulmonary vascular resistance, and improved echocardiography parameters. All patients suffered at least one adverse side effect of bosentan treatment, including peripheral edema, headache, abnormal liver function, muscle cramps, fluid retention, and vomiting. Although 15 of the 16 patients were taking hepatotoxic antiretroviral therapies and 4 patients were co-infected with chronic hepatitis B and C, only 2 or 16 were believed to have abnormal hepatic function, which the investigators considered to be within the range of prior experience. The study is published in the first issue for December 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
REDUCING COSTS IN TREATING OBSTRUCTIVE SLEEP APNEA PATIENTS
A large study showed that simpler, cheaper methods can be used to determine the optimal pressure for continuous positive airway pressure (CPAP) devices which are used to successfully treat a serious disorder, obstructive sleep apnea. Researchers reported results on 315 patients in a multicenter trial designed to determine whether optimizing pressure levels at home with an autoadjusted CPAP device or using a predicted formula was as effective as determining levels through the more expensive, time-consuming full night sleep test. (Obstructive sleep apnea is a serious disorder that occurs numerous times each night when a sleeping person temporarily stops breathing for 10 seconds or more, decreasing the amount of oxygen in the blood and brain, and increasing the carbon dioxide. The syndrome affects from 2 to 4 percent of the adult population.) As the most effective treatment for patients with this disease, the CPAP device is worn like an oxygen mask while sleeping, delivering a mixture of air and oxygen to the patient through the nose. It is designed to keep the airway open which aids in regular breathing. Study patients were divided into 3 groups. One group underwent a second sleep test (polysomnography) for manual CPAP pressure determination (titration). The second group received information on the autoCPAP, and then slept at home to determine effective pressure. The third group had optimal pressure estimated from a published equation. A total of 82 percent of the autoCPAP patients titrated their pressure the first night at home. Optimum CPAP pressure was attained by 96 percent of all subjects in the autoadjusted group. The authors said that improvement in symptoms such as sleepiness, arousal index, oxygen saturation, and apnea/hypopnea index was very similar in all three groups, although the predicted formula group had a higher number of residual apneas and hypopneas. The study is published in the first issue for December 2004 of the American Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
IMPROVING DIAGNOSIS BY MOLECULAR METHODS FOR DIFFICULT VIRAL INFECTIONS
In a study of 148 bronchoalveolar lavage (BAL) specimens collected by analysis from patients with suspected hard-to-detect acute respiratory infections, only about 1 in 3 cases that were identified as virus positive by molecular methods were also revealed through conventional cell culture analysis. The investigators analyzed the specimens for the presence of 11 different viruses, as well as several types of pneumonia, plus Legionnaire's Disease. Respiratory viruses were identified in 34 of 117 BAL specimens (29 percent) obtained in patients with suspected respiratory infection and in only 2 of 31 control patients without respiratory symptoms. The researchers used reverse transcription chain-reaction assay for their analysis. According to the authors, viruses in the lower respiratory tract are a leading cause of disease, hospitalization, and antibiotic use in patients with immunosuppressive and/or chronic lung diseases. However, in 70 to 80 percent of the cases, the identity of the virus remains undetermined. (To collect BAL specimens, doctors wedge a bronchoscope into a small airway in the lung, and then instill saline solution through the instrument. The fluid is then suctioned back through the scope, bringing back cellular material for analysis.) The investigators said that their sensitive molecular tool better estimated the frequency of respiratory viral infection in hospitalized patients and permitted the identification of the cause of a respiratory event in patients who did not respond to conventional empirical antibiotic treatment. The study appears in the first issue for December 2004 of the Americana Thoracic Society's peer-reviewed American Journal of Respiratory and Critical Care Medicine.
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Journal
American Journal of Respiratory and Critical Care Medicine