It is generally assumed that ventilation is necessary for oxygenation. This study tested if paralyzed animals without respirations can maintain arterial oxygenation when administered high-flow oxygen delivered by a catheter in the trachea.

Design: Prospective observational study. Setting: University research laboratory. Participants: 3 anesthetized/paralyzed swine weighing 29.5 ± 4.2 kg. Interventions/observations: Pigs were intubated, anesthetized with intravenous tiletamine and a pentobarbital drip. A femoral arterial line was placed to record arterial blood gases and vital signs every 5 minutes. Respiratory paralysis was obtained with vecuronium 150 μg/kg and repeated at any sign of movement. A catheter was placed in the trachea to deliver oxygen at 15 L/min. Outflow gas from the endotracheal tube was analyzed for O₂ and CO₂. O₂ was discontinued at 75 minutes. The institutional animal care and use committee approved the protocol.

All pigs survived to 75 minutes. Pao₂ was more than 100 mm Hg throughout the study period. Mean Paco₂ was 37.4 ± 2.8 mm Hg at baseline, 146 ± 59 at 30 minutes, then rose above 200 mm Hg in all pigs by 45 minutes. Mean arterial pH fell from 7.47 ± 0.04 at onset to 6.75 ± 0.06 at 75 minutes. When oxygen was terminated at 75 minutes, Pao₂ fell to 16.5 ± 7.6 mm Hg within 5 minutes, and all pigs were sacrificed within 10 minutes. For outflow gas, O₂ was more than 98% and expired CO₂ less than 1% throughout the study period.

Paralyzed, unventilated pigs receiving high-flow oxygen via a tracheal catheter remained alive after 75 minutes, although a profound respiratory acidosis developed.