Nitrogen-13 and xenon-133 ventilation studies.

Due to the solubility of xenon-133 in blood and tissues, errors are introduced in the determination of regional pulmonary ventilation. We investigated these errors by comparing the results from ventilation measurements with Xe-133 and N-13 in five normal subjects (both at rest and during exercise) and in seven patients after a pneumonectomy. In the normal subjects at rest, the upper lung fields showed no significant difference in the uptake rates of the two gases. In the middle and lower lung fields, however, the uptake rate for Xe-133 was higher than for N-13. During exercise a significant increase of the specific ventilation was found in the upper lung fields for N-13 compared with Xe-133. In the pneumonectomy patients the overall uptake rate for Xe-133 in the intact hemithorax was 25% larger than for N-13. Over the pneumonectomized hemithorax the uptake of the fastest component of Xe-133 was (8.5 +/- 1.3)% of the total. The total chest-wall contribution of Xe-133 was (27 +/- 8)% of the total count rate.