Night‐to‐night alterations in sleep apnea type in patients with heart failure

Summary In patients with heart failure, apnea type can shift overnight from mainly obstructive to mainly central in association with reductions in PCO2 and increases in periodic breathing cycle length, indicative of a fall in cardiac output. We hypothesized that the predominant apnea type could also vary from one night to another in association with alterations in PCO2 and cycle length. We studied 12 men with heart failure in whom the predominant apnea type changed from one night to the next over periods of at least 1 month, and two groups with either predominantly obstructive or central sleep apnea (OSA or CSA) in whom apnea type remained stable over time. In patients with unstable apnea type (n = 12, duration between sleep studies 9.0 ± 4.4 months), PCO2 was significantly lower (37.6 ± 1.6 mmHg versus 41.7 ± 1.9 mmHg, P