RESULTS	Multivariate analysis of patient characteristics ( age , sex , weight , FEV1 , FVC , diffusing capacity for carbon monoxide ( DCO ) , 6 ` WT distance ambulated , number of rests per 6 ` WT , and the maximal heart rate , blood pressure , rate-pressure product , respiratory rate , oxygen saturation , rating of perceived exertion , and amount of supplemental oxygen used during the 6 ` WT ) was performed on two groups of 30 patients each ( group A or B ) who were randomly assigned to either group by a process of random selection using a computer-generated random numbers program .\