Obstructive / mixed apnea index with arousals at 4% desaturation [(total number of obstructive apneas with aroual associated with >= 4% desaturation+ total number of mixed apneas with arousal associated with >= 4% desaturation) / (hours of sleep)]

RDI with arousals at all desaturations [(total number of apneas and hypopneas with arousal) / (hours of sleep)]