Respiration by tracheal insufflation of oxygen (TRIO) at high flow rates in apneic dogs.

Tracheal insufflation of oxygen (TRIO) is a technique in which oxygen is introduced into the trachea at a constant flow rate via a catheter advanced to the level of the carina. We studied the effects of flow rates (0.5, 1.0, 1.5 and 2.0 l.kg(-1).min(-1)) on arterial blood gases during TRIO in 6 apneic dogs. The constant flow was administered through the tip of a catheter (I.D. 2.0 mm) advanced to a site of 1 cm above the carina. After 30 min of TRIO, the mean Pa(CO)(2) at the flow rates of 0.5, 1.0, 1.5 and 2.0 l.kg(-1).min(-1) were 88 +/- 20, 76 +/- 20, 64 +/- 23 and 52 +/- 18 mmHg, respectively. CO(2) elimination increased as the flow rates increased from 0.5 to 2.0 l.kg(-1).min(-1). Based on the above study, we examined the effects of TRIO at a flow rate of 3 l.kg(-1).min(-1) in another 5 apneic dogs. TRIO, at a flow rate of 3 l.kg(-1).min(-1), was able to maintain normocarbia over 4 hr. The mean Pa(O)(2) and Pa(CO)(2) at 4.0 hr were 465 +/- 77 and 41 +/- 4 mmHg. Although the mechanism of pulmonary gas exchange during TRIO is unclear, our study is the first to document that normocarbia can be maintained by high-flow TRIO in apneic dots.