Oxygenation and ventilation were assessed in 15 postoperative patients before, immediately after, and 3 min after 15 sec of tracheobronchial suctioning in the presence or in the absence of high-frequency jet ventilation (HFJV). When HFJV was continued during suctioning, the mean PaO2 decrease was only 15 +/- 9 torr, compared to a 90 +/- 16 torr decrease when HFJV was discontinued. This difference demonstrates that continuation of HFJV during tracheobronchial suctioning prevents a decrease in PaO2.