Pathophysiological interactions of ventilation arousals, and blood pressure oscillations during Cheyne-Stokes respiration in patients with heart failure

Arousals from sleep can be associated with increases in blood pressure (BP) . However, it is uncertain whether this is due to a direct effect of arousa ls on BP, or is secondary to respiratory stimuli present at the time of the arousal. Cheyne-Stokes respiration (CSR) in patients with congestive heart failure (CHF) provides unique conditions that may allow these two possibil ities to be distinguished. In CSR, the apnea-hyperpnea cycle can be dissoci ated from arousals because when CSR occurs during wakefulness, it does so i n the absence of arousals, and when it occurs during sleep, arousals occur either at the termination of apnea (early arousals) or several breaths afte r the onset of hyperpnea (late arousals). We therefore measured BP during w akefulness and non-rapid eye movement (NREM) sleep in eight patients with C HF and CSR. During wakefulness, CSR was associated with wide fluctuations i n systolic BP (mean +/- SD, 11.3 +/- 6.0 mm Hg) synchronous with the apnea- hyperpnea cycle, in the absence of arousals. Similar fluctuations in BP wer e observed during CSR with early arousals (13.7 +/- 7.0 mm Hg) in NREM slee p. However, late arousals during CSR were associated with a small, but sign ificant additional effect on systolic BP (14.2 +/- 7.1 mm Hg, p < 0.05). Fu rthermore, the degree of BP increase following arousals was directly relate d to the associated increase in ventilation (r = 0.70, p < 0.05). We conclu de that BP fluctuations during CSR in patients with CHF are primarily relat ed to oscillations in ventilation during the CSR cycle and can occur in the absence of arousals. Arousals augment these BP oscillations, but only when they occur late in hyperpnea.