[Use of acetylene rebreathing to measure pulmonary tissue volume in patients undergoing hemodialysis].

Acetylene rebreathing was used to measure pulmonary tissue volume in 10 normal subjects and in 15 patients undergoing hemodialysis. A mixture containing 0.65% acetylene and 10% argon was rebreathed from the end-tidal level, and gas concentrations were measured with a mass spectrometer. Pulmonary tissue volume was computed from the difference between the argon equilibrium concentration and the corrected acetylene concentration, under the assumption that FAr was constant. Measured tissue volumes per unit lung volume (at functional residual capacity) in the normal subjects, before hemodialysis, and after hemodialysis were 0.204 +/- 0.042, 0.334 +/- 0.100, and 0.282 +/- 0.074, respectively. Tissues volumes per unit lung volume were significantly higher in the patients than in the normal subjects, even after hemodialysis. Tissues volumes per unit of lung volume decreased significantly during hemodialysis. Pulmonary blood flows per unit of body surface area of normal subjects, before hemodialysis and after hemodialysis were 3.004 +/- 0.791, 2.790 +/- 1.007, and 2.399 +/- 0.781 (l/min/m2), respectively. These volumes did not differ significantly between normal subjects and patients, and they decreased significantly during hemodialysis. Measured tissue volumes per unit of pulmonary blood flow for normal subjects, before hemodialysis, and after hemodialysis were 0.119 +/- 0.034, 0.167 +/- 0.024, and 0.166 +/- 0.030 (1/1/min), respectively. The values in the patients did not change during hemodialysis, but they were significantly higher than the volumes in the normal subjects.