Objective: To evaluate the role of ventilatory control in obstructive sleep apnea hypopnea syndrome (OSAHS).
Methods: Thirty-five patients with OSAHS were compared with 15 obese controls in pulmonary function, hypoxic ventilatory response (HVR), hypercapnic ventilatory response (HCVR) and polysomnography (PSG).
Results: (1) There were no differences in HVR and HCVR between patients with OSAHS and the control (t = 1.28, 0.57; P > 0.05). In OSAHS patients, HVR was correlated with nadir nocturnal oxygen saturation (MmS(P)O(2)) (r = -0.54, P < 0.01) and HCVR (r = 0.57, P < 0.01). (2) Patients with mild and moderate OSAHS had higher HVR than those with severe OSAHS (t = 2.74, P < 0.01). When 5 < or = apnea and hypopnea index (AHI) < 40, HVR was negatively correlated to forced expiratory volume in one second (FEV(1))/peak expiratory flow (PEF) (r = -0.42, P < 0.05) and AHI (r = -0.68, P < 0.01). For those whose AHI > or = 40, HVR was negatively correlated with MmSpO(2) (r = -0.58, P < 0.05) and positively correlated with HCVR (r = 0.59, P < 0.05).
Conclusion: In OSAHS patients, HCVR did not show significant change, but HVR showed two phasic change-increase first and then decrease-following the elevation of AHI, which was also related to MmSpO(2) and HCVR.