METHODS	In a randomized , placebo-controlled , double-blind , crossover trial , 23 patients with arterial ( n = 16 ) or chronic thromboembolic PH ( n = 7 ) and SDB defined as a mean nocturnal oxygen saturation < 90 % or dips ( > 3 % ) > 10/h with daytime Pao2 7.3 kPa were studied .\