Fig. 2
From: Effects of airway obstruction and hyperinflation on electrocardiographic axes in COPD
Upper panel: Estimated incremental clockwise rotation of the QRS axis based on FEV1 in univariate regression analysis (see Additional file 1: Table E1) for mild or severe airway obstruction (FEV1 60 or 30% predicted, GLI). Lower panel: Estimated incremental clockwise rotation of the QRS axis based on bivariate regression analysis taking into account both FEV1 and FRC (see Additional file 1: Table E1). The circle segments show the estimated effects of lung function on the electrical rightward rotation for four combinations of mild or severe obstruction (FEV1 60 or 30% predicted, GLI) with mild or severe hyperinflation (FRC 140 or 200% predicted, ECSC)