Cardiac Output During High Afterload Artificial Lung Attachment

Attachment of thoracic artificial lungs (TALs) can increase right ventricular (RV) afterload and decrease cardiac output (CO) under certain conditions. However, there is no established means of predicting the extent of RV dysfunction. The zeroth harmonic impedance modulus, Z0, was thus examined to determine its effectiveness at predicting CO during high afterload TAL attachment. The MC3 Biolung was attached in four adult sheep groups based on baseline (BL) pulmonary vascular resistance and TAL attachment mode: normal, parallel (n=7); normal, series (n=7); chronic pulmonary hypertension, parallel (n=5), and chronic pulmonary hypertension, series (n=5). The resistance of each attachment mode was increased incrementally and instantaneous pulmonary system hemodynamic data were acquired at each increment. The change in Z0 from BL, DeltaZ0, and percent change in CO (DeltaCO%) were then calculated to determine their relationship. The DeltaCO% varied significantly with DeltaZ0 (p<10(-40)) and DeltaZ02 (p<10(-4)) but not with the attachment and pulmonary hemodynamics group. The relationship between the variables for all sheep groups was DeltaCO%=0.215DeltaZ0(2)-7.14DeltaZ0+2.94 (R2=0.82) for DeltaZ0 in mm Hg/(L/min). Therefore, Z0 is an effective index for determining the CO during TAL attachment in both attachment modes with and without elevated pulmonary vascular resistance.