Body plethysmography allows to assess functional residual capacity (FRC(pleth)) and specific airway resistance (sRaw) as primary measures. In combination with deep expirations and inspirations, total lung capacity (TLC) and residual volume (RV) can be determined. Airway resistance (Raw) is calculated as the ratio of sRaw to FRC(pleth). Raw is a measure of airway obstruction and indicates the alveolar pressure needed to establish a flow rate of 1 L s(-1). In contrast, sRaw can be interpreted as the work to be performed by volume displacement to establish this flow rate. These measures represent different functional aspects and should both be considered. The measurement relies on the fact that generation of airflow needs generation of pressure. Pressure generation means that a mass of air is compressed or decompressed relative to its equilibrium volume. This difference is called "shift volume". As the body box is sealed and has rigid walls, its free volume experiences the same, mirror image-like shift volume as the lung. This shift volume can be measured via the variation of box pressure. The relationship between shift volume and alveolar pressure is assessed in a shutter maneuver, by identifying mouth and alveolar pressure under zero-flow conditions. These variables are combined to obtain FRC(pleth), sRaw and Raw. This presentation aims at providing the reader with a thorough and precise but non-technical understanding of the working principle of body plethysmography. It also aims at showing that this method yields significant additional information compared to spirometry and even bears a potential for further development.
To investigate the prevalence and type of peripheral neuropathies (PNP) in patients with chronic obstructive pulmonary disease (COPD), we studied lung function and blood gases, clinical signs of PNP, and neurophysiological function in 151 patients with COPD without known risk factors for PNP. Mean (SD) age was 65 (10) years, mean arterial PO2 was 59 (9) mmHg, mean ratio of forced expiratory volume in the first second to vital capacity (FEV1.0/VC) was 42 (12%). Thirty patients (20%) had clinically detectable and 6 (4%) had subclinical PNP of mild degree. Fourteen (9%) of the patients with clinically detectable PNP had symptoms due to PNP. Prevalence of PNP increased with severity of hypoxemia (p less than 0.05) and was more pronounced in the lower than in the upper limbs. Age and the degree of hypoxemia were predictors to differentiate between COPD patients with and without PNP. Although the cause of PNP in COPD patients remains unknown, our observations suggest that chronic hypoxemia may contribute to PNP.
A case of extrinsic allergic alveolitis (EAA) caused by Sphingobacterium spiritivorum is described. The symptoms were associated with the use of a steam iron. The water reservoir was heavily contaminated with S. spiritivorum (10 6 CFU ml ؊1 ). This is the first report of S. spiritivorum as a causative agent of EAA. CASE REPORTA 34-year-old woman presented with a dry cough, thorax constriction, and overall weakness. During the preceding 5 months, she had experienced these dry cough episodes twice a week. On examination, the patient was febrile (39°C), but a clinical lung examination showed no striking diagnostic findings. The high-resolution computer tomography-Roentgen image was normal; however, a lung function test showed a restriction of the vital capacity (71% of the adjusted reference value), and the diffusion capacity was also reduced (66 to 68%).During a hospital stay of several days' duration, the patient was free of discomfort. In the bronchoalveolar lavage specimen, the lymphocytes were increased up to 41% (norm, Ͻ10%), and neutrophils were increased up to 6% (norm, Ͻ2%) with a normal total cell count. This bronchoalveolar lavage specimen cell pattern indicated an acute phase of extrinsic allergic alveolitis (EAA; hypersensitivity pneumonitis). The erythrocyte sedimentation rate was increased up to 20/35 mm. The patient's conventional chest X ray and high-resolution computer tomography images were free of any alterations, based on criteria outlined previously (11).The patient's detailed history revealed that she had used an iron before each of the episodes of discomfort. She had used a steam iron which is additionally equipped with a liquid reservoir for wetting of the clothes.Using the agar gel diffusion test (Ouchterlony assay described previously [13]), the water of this liquid reservoir showed a clear precipitation line with the serum of the patient, indicating the presence of precipitating immunoglobulin G (IgG) antibodies in the serum of the patient against antigens in the water.No IgG antibodies could be detected against a wide panel of organisms which are commonly associated with EAA, including Saccharopolyspora rectivirgula, Thermoactinomyces vulgaris, Aspergillus fumigatus (also not in an IgG immunoblot),
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