VENTILATORY CONTROL IN PATIENTS WITH SLEEP-APNEA AND LEFT-VENTRICULARDYSFUNCTION - COMPARISON OF OBSTRUCTIVE AND CENTRAL SLEEP-APNEA

Sleep apnoea is common in patients with heart failure, While most pati ents have central sleep apnoea (CSA), a minority have obstructive slee p apnoea (OSA),The pathophysiology of CSA is not well understood. We h ypothesized that central chemosensitivity would be an important pathop hysiological factor in patients with CSA, and not in OSA, The aim of t his study was to compare ventilatory responses between patients with C SA and those with OSA, Acute ventilatory responses to eucapnic hypoxia and hyperoxic hypercapnia were measured during wakefulness in 34 pati ents (33 males and one female, aged 59+/-8 yrs (mean+/-SD)), with stab le medically-treated left ventricular dysfunction (LWD) and sleep apno ea (18 OSA and 16 CSA), Patients with CSA had a decreased awake end-ti dal carbon dioxide tension (4.1+/-0.5 kPa), increased ventilatory resp onse to carbon dioxide (0.65+/-0.43 L.min(-1).kPa PCO2-1), and eucapni c hypoxic responses in the normal range (0.6+/-0.4 L.min(-1)/% fall in arterial oxygen saturation (Sa,O-2)), In contrast, patients with OSA had normal end-tidal carbon dioxide tension (4.9-0.5 kPa), and normal ventilatory responses to hypercapnia (0.29+/-0.16 L.min(-1).kPa PCO2-1 ) and hypoxia (0.5+/-0.5 L.min(-1)/% fall in Sa,O-2). These findings s uggest that augmented chemosensitivity to hypercapnia may be an import ant factor in the pathophysiology of central sleep apnoea in patients with heart failure.