Figure 2.

Echocardiographic parameters assessed after breathing 15 min of oxygen therapy vs. 15 min of placebo air. (A) The systolic pulmonary arterial pressure. (B) The cardiac output. The boxplots show the median, the inter-quartile ranges, the minimum, the maximum, and outliers. The violin plots represent the distribution of the data, while the width represents the frequency. The mean is displayed as diamonds, and the dots represent the individual data. (C) The pulmonary resistance. The individual patient data are represented by dots, and the lines show the regression lines with standard errors. There is a left shift with oxygen therapy in the lower left corner compared with placebo air, but the resistance remains unchanged as both systolic pulmonary arterial pressure and cardiac output decreased with oxygen therapy. The cardiac output decreases by a reduction in heart rate, while the stroke volume remains constant.