Canine tracheal blood flow after endotracheal tube cuff inflation during normotension and hypotension.

Tracheal tissue damage associated with endotracheal intubation may be a direct result of high mucosal contact pressure (MCP) generated by the endotracheal tube cuff. Tracheal blood flow (TBF) was measured at MCPs in the normotensive and hypotensive (mean arterial blood pressure, 50 mm Hg) canine model. Control TBFs through the individual rings in contact with the endotracheal tube cuff ranged between 26.6 +/- 2.7 and 44.5 +/- 5.0 with a mean of 35.0 +/- 2.5 mL.min-1 x 100 g-1 during normotension, and 15.0 +/- 4.9 and 22.5 +/- 5.0 with a mean of 18.9 +/- 0.9 mL.min-1 x 100 g-1 during hypotension. TBF was reduced significantly at all elevated MCPs in both groups. TBF also was measured during normotension and hypotension after cuff inflation to 15 mm Hg MCP at 1-h intervals for 3 h. TBF was reduced significantly from control to 14.9 +/- 1.5 mL.min-1 x 100 g-1 after 1 h during normotension, and continued to decline to 6.1 +/- 0.9 mL.min-1 x 100 g-1 after 3 h. During hypotension, TBF decreased significantly from control to 6.1 +/- 0.6 mL.min-1 x 100 g-1 at 1 h and remained unchanged at 3 h. These findings suggest that even at 20 mm Hg MCP, significant reductions in TBF may occur. For prolonged endotracheal intubation, especially during hypotension, significant reductions in TBF may occur at even lower MCP.