Decreased hypoxic ventilatory chemoresponsiveness and clinical features in patients with narcolepsy cataplexy

Abstract

To explore the relationship between hypoxic responsiveness of the patients with narcolepsy-cataplexy and their clinical features. A total of 113 patients with narcolepsy-cataplexy (narcolepsy group) at Peking University People's Hospital from June 2007 to May 2008 and 128 gender-age matched volunteers (control group) were recruited. And their status of human leukocyte antigen (HLA)-DQB1*0602 was examined to differentiate hypercapnic and hypoxic responsiveness. Among them, 93 patients with severe hypersomnolence had hypercapnic and hypoxic responsiveness tested before and after the treatment of methylphenidate and another 20 with severe cataplexy did the same before and after the treatment of chlorimiopramine. Compared with the control group, the narcolepsy group had depressed hypoxic responsiveness ((-0.135 ± 0.105) vs (-0.223 ± 0.136) L×min⁻¹ × %SpO₂⁻¹, P < 0.001). After the treatment of methylphenidate, sleepiness improved significantly in all 93 patients, but their low hypoxic responsiveness did not change ((-0.151 ± 0.111) vs (-0.149 ± 0.105) L×min⁻¹× % SpO₂⁻¹, P = 0.780). After the treatment of chlorimiopramine, cataplexy also improved in 20 patients.However their low hypoxic responsiveness had no change ((-0.114 ± 0.054) vs (-0.115 ± 0.065) L×min⁻¹ × %SpO₂⁻¹, P = 0.949). Lower hypoxic responsiveness in narcolepsy group is not related with the clinical features of disease.