Carbon Dioxide added late in Inspiration Reduces Ventilation-perfusion Heterogeneity without causing Respiratory Acidosis
Thomas V Brogan, H Thomas Robertson, Wayne J E Lamm, Jennifer E Souders, Erik R Swenson. J Appl Physiol (1985). 2004 May;96(5):1894-8. doi: 10.1152/japplphysiol.00160.2003. Epub 2003 Dec 5.
We have shown previously that inspired CO2 (3-5%) improves ventilation-perfusion (Va/Q) matching but with the consequence of mild arterial hypercapnia and respiratory acidosis. We hypothesized that adding CO2 only late in inspiration to limit its effects to the conducting airways would enhance Va/Q matching and improve oxygenation without arterial hypercapnia. CO2 was added in the latter half of inspiration in a volume aimed to reach a concentration of 5% in the conducting airways throughout the respiratory cycle.