Colonic oxygen microbubbles augment systemic oxygenation and CO 2 removal in a porcine smoke inhalation model of severe hypoxia.

Inhalation injury can lead to pulmonary complications resulting in the development of respiratory distress and severe hypoxia. Respiratory distress is one of the major causes of death in critically ill patients with a reported mortality rate of up to 45%. The present study focuses on the effect of oxygen microbubble (OMB) infusion via the colon in a porcine model of smoke inhalation-induced lung injury. Juvenile female Duroc pigs (n = 6 colonic OMB, n = 6 no treatment) ranging from 39 to 51 kg in weight were exposed to smoke under general anesthesia for 2 h. Animals developed severe hypoxia 48 h after smoke inhalation as reflected by reduction in SpO 2 to 66.3 ± 13.1% and PaO 2 to 45.3 ± 7.6 mmHg, as well as bilateral diffuse infiltrates demonstrated on chest X-ray. Colonic OMB infusion (75-100 mL/kg dose) resulted in significant improvements in systemic oxygenation as demonstrated by an increase in PaO 2 of 13.2 ± 4.7 mmHg and SpO 2 of 15.2 ± 10.0% out to 2.5 h, compared to no-treatment control animals that experienced a decline in PaO 2 of 8.2 ± 7.9 mmHg and SpO 2 of 12.9 ± 18.7% over the same timeframe. Likewise, colonic OMB decreased PaCO 2 and PmvCO 2 by 19.7 ± 7.6 mmHg and 7.6 ± 6.7 mmHg, respectively, compared to controls that experienced increases in PaCO 2 and PmvCO 2 of 17.9 ± 11.7 mmHg and 18.3 ± 11.2 mmHg. We conclude that colonic delivery of OMB therapy has potential to treat patients experiencing severe hypoxemic respiratory failure.