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 th e endotracheal tube cuff. Tracheal blood flow (TBF) was measured at MC Ps in the normotensive and hypotensive (mean arterial blood pressure, 50 mm Hg) canine model. Control TBFs through the individual rings in c ontact 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-1.100 g-1 during norm otension, and 15.0 +/- 4.9 and 22.5 +/- 5.0 with a mean of 18.9 +/- 0. 9 mL.min-1.100 g-1 during hypotension. TBF was reduced significantly a t all elevated MCPs in both groups. TBF also was measured during normo tension and hypotension after cuff inflation to 15 mm Hg MCP at 1-h in tervals for 3 h. TBF was reduced significantly from control to 14.9 +/ - 1.5 mL.min-1.100 g-1 after 1 h during normotension, and continued to decline to 6.1 +/- 0.9 mL.min-1.100 g-1 after 3 h. During hypotension , TBF decreased significantly from control to 6.1 +/- 0.6 mL.min-1.100 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 pr olonged endotracheal intubation, especially during hypotension, signif icant reductions in TBF may occur at even lower MCP.