Tracheal insufflation of O2 (TRIO) at low flow rates sustains life for several hours

The emergency management of respiratory arrest can be a difficult problem. The authors hypothesized that tracheal insufflation of O2 (TRIO) at low flows could provide adequate oxygenation and sufficient CO2 elimination to sustain life until more definitive (but more difficult to implement) measures could be applied. Therefore, 10 anesthetized, paralyzed dogs (15.9-48.2 kg), initially ventilated with conventional mechanical ventilation (CMV) using room air, were studied. CMV was stopped and a 1- or 5-mm id catheter with a constant flow (V) of O2 ranging from 0.2 to 3.0 l/min was inserted to within 1 cm of the carina. With all flow rates, PaO2 and PaCO2 initially increased with time; the rate of increase of PaO2 was greater and that of PaCO2 was less, with increasing V. In three dogs studied at flow rates of 2.0 or 3.0 l/min, arterial blood gases reached a plateau after about 2 h: pH = 6.87; PCO2 = 164 mmHg; and PO2 = 363 mmHg (mean values). These studies were stopped at between 4 and 5 h, with no dogs showing any signs of cardiovascular or other decompensation. Results in which catheter position was studied indicated that as long as the catheter tip was at or past the carina, gas transport was similar to that observed when the catheter tip was 1 cm proximal to the carina. The authors conclude that TRIO at low flow rates can produce sufficient gas exchange to support life for prolonged periods in apneic dogs.