Keith Michael Vogt1, James W. Ibinson2, Robert H. Small1, Petra Schmalbrock3
1Anesthesiology, The Ohio State University, Columbus, OH, USA; 2Anesthesiology, University of Pittsburgh Medical Center, Pittsburgh, PA, USA; 3Radiology, The Ohio State University, Columbus, OH, USA
Functional MRI data was acquired during normal ventilation and paced hyperventilation that caused a 35% decrease in end-tidal CO2 (ETCO2). Respiratory motion and expired CO2 data were collected and respiratory volume over time (RVT) and ETCO2 values were calculated. Although negatively correlated, the RVT and ETCO2 timecourses did not strictly mirror each other. RVT and ETCO2 values were convolved with appropriate response functions and regressed against each voxel timecourse. The ETCO2 regressor was more strongly and diffusely correlated to the FMRI data, suggesting that ETCO2 monitoring may be warranted in studies with large changes in respiration.