FIG. 8:  This Figure represents >400 data points from a group of 40 patients with heart failure quantifying the effects of obstructive and central events on stroke volume.^[2]  There was a large fall of approximately a mean 9% in stroke volume during obstructive apneas and a mean fall of about 6% during obstructive hypopneas.  In contrast, during central hypopneas there was an increase in stroke volume of approximately 2%, versus an increase of about 3% during central apneas.  So again, obstructive and central apneas have diametrically opposite effects on stroke volume in patients with heart failure.