[Study of chemosensitivity in patients believed to have sleep apnea syndrome]

We performed polysomnography and measured hypoxic ventilatory (HVR), hypercapnic ventilatory responses (HCVR) in 42 patients (60 +/- 11 years) with obesity and a clinical suspicion of sleep apnea syndrome (SAS) in order to determine whether an altered chemosensitivity was associated with SAS. The apnea/hypopnea index was 38 +/- 20 events per hour of sleep in 28 patients (SAS+ group) and less than 10 in the 14 others (SAS- group). The 2 groups differed only by a lower waking PaO2 in SAS+ as compared to SAS- (71.0 +/- 9 vs 77.4 +/- 8 mmHg, p < 0.05). HVR and HCVR were not significantly different in the 2 groups (0.82 +/- 0.58 vs 0.86 +/- 0.37 l.min-1.%-1; 1.41 +/- 0.81 vs 1.40 +/- 0.67 l.min-1.mmHg-1, respectively). In SAS+ group, HVR or HCVR did not change 3 or 12 months after continuous positive airway pressure (CPAP) therapy while both polysomnography and PaO2 returned to normal. We conclude that in patients with mild obesity and SAS there is no difference in chemosensitivity due to the presence of sleep apnea and that CPAP therapy does not alter these measurements. These results suggest no direct effect of SAS on chemosensitivity in the population studied.