Critical behavior of random walks

Cardiopulmonary exercise testing is commonly used to assess patients with heart failure. Analysis of expired gases during exercise requires the use of either a facemask or mouthpiece with nose clip. The authors sought to determine if the method of expired gas collection during exercise testing (facemask or mouthpiece) influences gas exchange measurements in patients with heart failure. Nine patients with heart failure performed two maximal treadmill tests. Expired gases were collected with a facemask in one exercise test and a mouthpiece in the other. There were no significant differences in exercise test duration, peak oxygen uptake, heart rate, respiratory exchange ratio, or perceived exertion during maximal exercise performed with the facemask when compared to the mouthpiece. Test subjects reported that the overall comfort of the facemask was significantly greater than that of the mouthpiece (P < .02). The method of expired gas collection during cardiopulmonary exercise testing does not significantly affect measures of gas exchange or exercise performance in patients with heart failure. Heart failure patients find the overall comfort of the facemask superior to that of the mouthpiece, but this comfort preference does not affect exercise performance.