A computed tomographic scan assessment of endotracheal suctioning-induced bronchoconstriction in ventilated sheep

This study was directed at assessing changes in bronchial cross-sectional s urface areas (BCSA) and in respiratory resistance induced by endotracheal s uctioning in nine anesthetized sheep. Cardiorespiratory parameters (Swan-Ca nz catheter), respiratory resistance (inspiratory occlusion technique), BCS A, and lung aeration (computed tomography) were studied at baseline, during endotracheal suctioning, and after 20 consecutive hyperinflations. Measure ments performed initially at an inspired oxygen fraction (Fl(O2)) of 0.3 we re repeated at an Fl(O2) of 1.0. At an Fl(O2) of 0.3, endotracheal suctioni ng resulted in atelectasis, a reduction in BCSA of 29 +/- 23% (mean +/- SD) , a decrease in arterial oxygen saturation from 95 +/- 3% to 87 +/- 12% (p = 0.02), an increase in venous admixture from 19 +/- 10% to 31 +/- 19% (p = 0.006), and an increase in lung tissue resistance (DRrs) (p = 0.0003). At an Fl(O2) of 1.0, despite an extension of atelectasis and an increase in pu lmonary shunt from 19 +/- 5% to 36 +/- 2% (p < 0.0001), arterial O-2 desatu ration was prevented and BCSA decreased by only 7 +/- 32%. A recruitment ma neuver after endotracheal suctioning entirely reversed the suctioning-induc ed increase in DRrs and atelectasis. In three lidocaine-pretreated sheep, t he endotracheal auctioning-induced reduction of BCSA was entirely prevented . These data suggest that the endotracheal suctioning-induced decrease in B CSA is related to atelectasis and bronchoconstriction. Both effects can be reversed by hyperoxygenation maneuver before suctioning in combination with recruitment maneuver after suctioning.