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A single gastric-esophageal probe, 5 mm in diam, with two transducers mounted near the tip has been used to measure transdiaphragmatic pressure in human subjects. The transducers are linear up to at least 200 cmH2O pressure and provide equal deflections for both positive and negative pressures. The method is shown to give results comparable to the standard procedure using two balloon-tipped catheters, one in the stomach and one in the esophagus.

Forty two of 125 former workers in a factory in Syracuse, New York, which manufactured hard metal parts from tungsten carbide and cobalt, were studied by chest radiographs, spirometry, and plethysmographically determined lung volumes. The plant was closed in 1982 and the studies were performed in 1983-5. Recorded measurements of carbide dust concentrations were only mildly excessive by modern standards, but deceitful efforts to reduce the apparent concentration of dust were known to have occurred during an inspection by the Occupational Safety and Health Administration. Lung biopsies in four cases in the study and necropsy in one of the 83 cases not studied during life showed giant cell interstitial pneumonia and appreciable concentrations of tungsten carbide. This information indicates that exposure was substantial. Four workers had evidence of pulmonary fibrosis by chest radiographs; two of these workers had normal pulmonary function. Fourteen had abnormal pulmonary function, five of whom had a restrictive pattern, eight a pattern of air trapping, and one a combined pattern. Thus radiographic, or functional abnormalities, or both occurred in 16 of the 42 cases studied. No correlation with duration of exposure was established. Progressive clinically important disease (one fatal) has been found in four ex-workers, two in each of the restrictive and air trapping groups.These findings suggest that poorly regulated dust concentrations in a hard metals factory possibly cause pulmonary abnormalities and sometimes severe illness. Material and methods Demand for hard metal machine tools expanded rapidly in the 1970s. Consequently the plant studied underwent major expansion in the 1960s and 1970s. The production process involved mixing raw materials including tungsten carbide, cobalt, tantalum, and traces of other metals. These metals were mixed in powdered form. Different grades of finished products required varying amounts ofcobalt in the mix with proportions up to 24%. Once mixed the materials were pressed into bars and then heated in a sintering furnace. The sintered pieces were machined to shape and reheated. After the reheating the hardened pieces were finished with various machining processes including grinding, lathing, and cutting.As product demand increased, more machinery

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A series of experiments was undertaken in a total of 95 adult subjects, of whom 25 had coronary artery disease, to evaluate the extrapolation (Defares) CO2 rebreathing method vs. the equilibrium (Collier) method for estimating mixed venous CO2 tension. Collier values were corrected for the downstream effect, whereas Defares values were uncorrected. Although the methods gave similar mean values in separate series with normal subjects walking on a treadmill set at 123 W for 3 min, Collier values had a coefficient of variation (CV) of 2.5% in duplicate determinations and Defares values had a CV of 4.5%. In paired comparisons Defares values averaged either higher or lower than Collier values depending on variations in technique and the analysis of Defares tracings. Collier values were essentially unaffected by the duration of the rebreathing period (10 vs. 15 s). The Collier technique appears to be superior for the exercise evaluation of cardiac output in healthy and diseased subjects when the goal is obtain values at 82 or 123 W in single test sessions.